首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 367 毫秒
1.
A new chitosan derivative has been synthesized by crosslinking a metal complexing agent, [6,6′-piperazine-1,4-diyldimethylenebis (4-methyl-2-formyl) phenol] (L), with chitosan (CTS). The resulting material (CCTSL) was characterized by elemental (CHN), spectral (FTIR and solid-state NMR), thermal (TGA and DTA), and structural (powder XRD and SEM) analyses. Adsorption experiments (pH dependency, kinetics, and equilibrium) of CCTSL toward various metal ions such as Mn(II), Fe(II), Co(II), Cu(II), Ni(II), Cd(II), and Pb(II) were carried out at 25 °C. The results showed that the adsorption was dependent on the pH of the solution, with a maximum capacity between pHs 6.5 and 8.5. The kinetics was evaluated by applying the pseudo-first-order and pseudo-second-order equation models and the equilibrium data were analyzed by Langmuir isotherm model. The maximum adsorption capacity was 1.21 mmol g−1 for Cu(II) and the order of adsorption capacities for the metal(II) ions studied was found to be Cu(II) > Ni(II) > Cd(II)  Co(II)  Mn(II)  Fe(II)  Pb(II).  相似文献   

2.
Microbial reduction of soluble uranyl [U (VI)] to insoluble uraninite by sulfate reducing bacteria (SRB) is a promising remediation strategy for uranium-contaminated groundwater. Effects of environmental factors, including pH and coexisting ions, on U (VI) bioreduction processes (UBP) remain unknown. Anaerobic batch experiments were performed to evaluate impact on UBP. Kinetic investigations with varied pH demonstrated that U (VI) was reduced mostly within 48 h. The bioprecipitation yields depended strongly on pH, increasing from 12.9% to 99.4% at pH 2.0 and 6.0, respectively. Sulfate concentration 4000 mg l−1 did not affect UBP; however, sulfate concentration 5000 mg l−1 significantly slowed UBP. Biogenic H2S produced during sulfate reduction was not directly involved in UBP. At 20 mg l−1 Zn or 10 mg l−1 Cu, no UBP inhibition was observed and uraninite was detected in metal sulfide precipitate. However, 25 mg l−1 Zn or 15 mg l−1 Cu stopped UBP completely. Cu toxicity mechanism probably differed from Zn. The ability to reduce U (VI) was lost permanently with exposure to 15 mg l−1 Cu, but not for Zn 25 mg l−1. No uraninite could be detected before nitrate removal, suggesting nitrate strongly inhibited UBP, which may possibly be related to denitrification intermediates controlling the solution redox potential.  相似文献   

3.
Wang Y  Liu Y  Han R  Yang J  Zhu Z  Zhang Y  Yao Z  Gao W  Shen Z 《Cytokine》2008,41(3):240-243
Aim: The aim of this study was to analyze the expression levels of plasma soluble Fas (sFas) and soluble Fas ligand (sFasL) in patients with orthotopic liver transplantation (OLT) procedures routinely performed without venovenous bypass. Methods: The sFas and sFasL were analyzed in the blood of 20 consecutive patients who underwent transplantation. Blood samples were drawn from the radial artery at serial time points before, during, and after surgery. Plasma levels of sFas and sFasL were detected by Enzyme Linked-Immuno-Sorbent Assay. Plasma aspartate transaminase (AST) and alanine transaminase (ALT) were assayed by routine clinical chemistry testing. Results: Marked elevation of plasma AST and ALT were detected at the reperfusion and postoperation time points (P < 0.001), with a peak on the first postoperative day. The mean plasma concentration of sFas and sFasL remained unchanged from preoperative to anhepatic phase (T1 to T3) (P  0.268). The sFas and sFasL concentrations were significantly higher at 15 and 60 min after reperfusion compared to the preoperative value (P  0.048). Postoperatively, sFas and sFasL concentration were decreased to preoperative levels on the first postoperative day (P  0.127). Conclusion: The sFas and sFasL seem to be involved in reperfusion injury during OLT. The understanding of Fas may provide new insights into the mechanisms of ischemia/reperfusion injury during OLT.  相似文献   

4.
Interleukin-6 and procalcitonin in children with sepsis and septic shock   总被引:3,自引:0,他引:3  
Objectives. To examine the behavior of interleukin-6 (IL-6) and procalcitonin (PCT) and verify whether they can be used to differentiate children with septic conditions. Methods. Septic children aged between 28 days and 14 years, prospectively enrolled from 01/2004 to 12/2005, were divided into sepsis (SG; n = 47) and septic shock (SSG; n = 43) groups. IL-6 and PCT were measured at admission (T0) and 12 h later (T12h). PCT results were classed as: 0.5 ng/mL = sepsis unlikely; 0.5 to <2 = sepsis possible; 2 to <10 = systemic inflammation; 10 = septic shock. Results. Ninety children were included. At T0, there was a higher frequency of SSG with higher PCT compared with SG [SSG: 30 (69.7%) > SG: 14 (29.8%); p < 0.05]. Similar results were observed at T12h. PRISM was significantly higher for SSG patients with higher PCT than SG patients. At T0, IL-6 levels were higher in SSG [SSG: 213.10 (10.85–396.70) > SG: 63.21 (0.86–409.82); p = 0.001], but not statistically different at T12h. IL-6 levels positively correlated with PRISM score in SSG patients at admission (p = 0.001; r = 0.86). Conclusion. PCT and IL-6 appear to be helpful in early assessment of pediatric sepsis, are of diagnostic value at admission, and are related to disease severity.  相似文献   

5.
Oligonucleotide chip-based assays can be a sample-thrifty, time-saving, routine tool for evaluation of chemical-induced DNA strand breaks. This article describes a novel approach using an oligonucleotide chip to determine photosensitizer-induced DNA single-strand breaks. Surface coverage of fluorophore-labeled oligonucleotides on silicon dioxide chip surfaces was determined on alkaline phosphatase digestion. Fluorescence maxima (at 520 nm) of the solutions were converted to molar concentrations of the fluorescein-modified oligonucleotide by interpolation from a predetermined standard linear calibration curve. The photosensitizing activity of chlorpromazine and triflupromazine toward DNA single-strand breaks was then studied at different drug doses and also as a function of photoirradiation time. Photoinduced single-strand breaks calculated using the method described here agreed with values predicted by theoretical extrapolation of the single-strand breaks obtained for plasmid DNAs from agarose gel electrophoresis, and thereby indirectly validated the chip-based assays. Under UV irradiation (93.6 kJ/m2) chlorpromazine (0.08 mM) was found to have significant photogenotoxicity. However, triflupromazine did not exhibit any (photo)genotoxicity over the concentration range studied (0.04–0.20 mM). The method developed will be useful for quantitative screening of drug genotoxicity in terms of induction of breaks in DNA.  相似文献   

6.
The biomass of Corynebacterium glutamicum was treated with poly(amic acid) to improve the biosorption of Basic Blue 3 (BB3) from aqueous solution. The grafting of poly(amic acid) onto the biomass surface increased the density of the carboxyl groups. The UV-spectrum revealed that strong acidic (pH  2) and basic conditions (pH  11) resulted in the precipitation of BB3. Therefore, pH edge experiments were conducted only within the range 3–10; these results indicated that electrostatic attraction between carboxyl groups of C. glutamicum and BB3 dye cations was favored under alkaline conditions. From the Langmuir model, poly(amic acid)-modified biomass gave a maximum uptake of 173.6 mg/g at pH 9, compared to 52.8 mg/g by the raw biomass. The biosorption kinetics was found to be fast; with equilibrium attained within 10 min. The increase in the ionic strength strongly affected the uptake of BB3 for both forms of C. glutamicum.  相似文献   

7.
Objective: To study the significance of persistent (12 months) new autoantibodies, in Juvenile Idiopathic Arthritis (JIA) patients treated with either Infliximab (INFL) or Etanercept (ET) for 2 years. Patients-methods: 26 children under INFL (n = 12) or ET (n = 14) were prospectively studied. A large panel of autoantibodies was tested using indirect immunofluorescence (ANA, anti-dsDNA, anti-ENA, SMA, LKM, AMA, PCA, anti-R1, ATA), ELISA (ANA, anti-ENA, anti-cardiolipin, ANCA), immunoblotting assay (anti-ENA: anti-Ro, anti-La, anti-Sm, anti-URNP, anti-Jo, anti-Scl70, anti-centromere, anti-ribosomal and anti-histone) and rate nephelometry (RF). Results: Apart from the positive patients for ANA (13/26) and RF (2/26) prior to anti-TNF treatment, 6/26 patients (23%) developed new autoantibodies (SMA, anti-R1, ATA) which persisted for 12–50 months. None developed antibodies to nuclear antigens. In only one case, ATA was associated with the development of Hashimoto’s thyroiditis. Conclusions: These findings indicate that in JIA patients in contrast to adult RA patients, development of new autoantibodies to various nuclear antigens is rare. Other non relevant to rheumatic diseases autoantibodies, may appear and persist for >12 months, but very rarely they may be related to clinical entities, especially in the presence of a positive family history of autoimmunity.  相似文献   

8.
This study evaluates the effects of fragmentation on the spatial and temporal dynamics of small litterfall production in Atlantic rainforest in Pernambuco State, Brazil. Litterfall was collected for 24 months at two 0.2 ha sites, located in the forest edge zone and the forest interior, within a rainforest patch of about 300 ha. Structural parameters of both forest sites were recorded. Litter was sorted into six fractions (foliage, twigs, buds/flowers, fruits/seeds, peduncles, rest), dried and weighed. The interior forest plot contained 314 live trees with a dbh 5 cm and a stand basal area of 41.8±8.7 m2, whereas the forest edge contained 211 live trees and a stand basal area of 23.4±3.6 m2. Total small litterfall was extraordinarily high and totalled 12.62±4.73 t ha−1 yr−1 in interior forest and 14.74±2.78 t ha−1 yr−1 in forest edge. High litterfall rates are probably due to a pronounced periodicity, edge effects alter litterfall strongly.  相似文献   

9.
A study of temporal and spatial distribution of zooplankton frequently requires identification to species level. In such studies, samples are usually fixed, but according to different authors rotifer genera such as Synchaeta (Ehrenberg, 1832) can only be identified in live samples. A procedure for the identification of preserved specimens of Synchaeta is presented, permitting ecological studies without the examination of live material. Trophus morphology, investigated by light and scanning electron microscopy, was related to morphological characteristics of preserved specimens. In this way, body length was used to group formalin-preserved specimens into Synchaeta gr. tremula-oblonga sensu Ruttner-Kolisko (1974) (170 μm) or Synchaeta gr. stylata-pectinata sensu Ruttner-Kolisko (1974) (190 μm). Furthermore, body length, colour and shape were used to identify Synchaeta grandis (Zacharias, 1893), Synchaeta pectinata (Ehrenberg, 1832), Synchaeta kitina (Rousselet, 1902) and Synchaeta lakowitziana (Lucks, 1930). It was, however, impossible to distinguish Synchaeta tremula (Müller, 1786) from Synchaeta oblonga (Ehrenberg, 1832) by their trophi because of contradictions in the diagnostic keys and monographs regarding trophus morphology.  相似文献   

10.
When dried organisms are immersed in water, rapid imbibition may cause severe damage to plasma membranes; in unicellular organisms, such damage is usually lethal. This study investigated effects of water activity (dryness) of organisms and immersion temperature on imbibitional damage in three insect pathogenic fungi. Conidial powders of Beauveria bassiana (Bb), Metarhizium anisopliae (Ma) and Metarhizium acridum (Mac) were dried/hydrated to a broad range of water activities (aw) (0.023–0.961) prior to immersion in water at 0.5–33 °C. Imbibitional damage in conidia of each fungus occurred rapidly, with no differences in viabilities observed following immersion for 2 vs. 60 min. Damage increased with decreasing water activity of the conidia and decreasing temperature of the immersion water. Dry (aw  0.333) Metarhizium spp. conidia were highly susceptible to imbibitional damage, with viability declining to 5% after immersion at 0.5 °C and 63% following immersion at 15 °C. Germination of the driest Ma conidia was reduced to 66% after treatment at 25 °C. In contrast, Bb was highly tolerant to damage, with significant reductions in viability (to levels as low as 43–65%) occurring only when dry conidia were immersed at 0.5 °C. Damage was prevented when conidia were slowly rehydrated by humidification prior to immersion and immersion temperature was increased to 33–34 °C; germination of all fungi was 94% under these optimal conditions. However, immersion of the driest Bb, Ma, and Mac powders in warm water (33 °C) also resulted in high viabilities (95%, 89%, and 94%, respectively), and slow-rehydrated conidia also retained high viability (87%, 92%, and 83%, respectively) after immersion in ice-cold water (0.5 °C). Formulation of conidia in pure (non-emulsifiable) paraffinic oil provided considerable protection from imbibitional damage. This study underscores a need for establishing standard protocols for preparing aqueous suspensions of sensitive fungi for both research and commercial applications.  相似文献   

11.
In France, whinchat Saxicola rubetra populations now rarely breed at altitudes below 1,000 m except in flooded alluvial plains. Whinchat reproductive success, the timing of haymaking and meadow bird density were assessed in 2003 in six areas selected in three different flooded plains, in five areas from two massifs at altitudes ranging from 990 to 1,250 m, and in 2004 in six areas of three flooded plains, in seven areas from three massifs at altitudes ranging from 1,200 to 2,000 m. The percentage of whinchat territories in which juveniles were observed was negatively correlated with mown areas at the time when 80% of hatched broods (observation of prey carryings by adults) would theoretically be fledged. Additionally, assessed hatching success was negatively correlated with early haymaking in 2003 and with meadow passerine territory density in 2004. In upland meadows, whinchat populations exhibited either low reproductive success and low density (1,200 m) or high reproductive success and high density (1,200 m). In lowland flooded meadow however, high density could match low reproductive success and whinchat population then acts as a sink population. We conclude that adequate agri-environmental policy should not focus only on lowland meadows, even if the highest meadow bird diversity is often found there.  相似文献   

12.
Questions : How do species diversity, frequency and composition in tussocks differ from those in similar sized plots outside tussocks? Does the extent of the differences depend on community types or environmental conditions? Location : A sub‐alpine grassland in the Swiss National Park. Methods : In each of the two communities (short grass and tall graminoid) differing in species composition, grazing intensity and soil nutrient availability, relevés were made in 40 pairs of small circular plots, with one plot located inside a randomly selected Carex sempervirens tussock and the other outside. Results : We found 92 vascular species, of which 46 had a frequency higher than 5%. Species richness (S), pooled cover, Shannon's diversity (H) and cumulative species number (CS) were higher outside than inside the C. sempervirens tussocks, but evenness (J) was lower. S, H and CS differed more in the tall graminoid community than in the short grass community. However, dissimilarity between the paired relevés inside and outside tussocks did not differ between the two communities. Of the 46 most frequent species, 12 were statistically more and only one less frequent outside than inside the tussocks. Vegetation inside and outside tussocks could be clearly distinguished in the ordination space. Conclusion : Vegetation inside C. sempervirens tussocks is different from that in the surrounding area and represents an impoverished but homogenized version of the surrounding vegetation. Although tussocks of C. sempervirens were systematically avoided by grazers, there is little evidence that tussocks facilitate the species growing inside them.  相似文献   

13.
The effect of reduced application rate, soil temperature at shallow depth (2.5 cm), and soil type on the efficacy of Steinernema carpocapsae against the navel orangeworm, Amyelois transitella, was evaluated in six field trials employing 1 m2 plots conducted from November 2003 through December 2004 in Madera and Kern Counties, California. Nematodes were applied at a concentration of 100,000 infective juveniles (IJs)/m2 (109/ha) in a volume of 187 ml water/m2 (1870 L/ha) with a post-application irrigation in all trials. Mortality ranged from 7.9 to 64.9% in successful trials and percent reduction in live larvae per plot was as high as 74.6%. Percent reduction and mortality were highly correlated (r2 = 0.78) and larval reduction typically was 10–11% greater than mortality for any treatment. In one trial, although nematode treatment significantly increased mortality compared to the controls, the treatment was deemed unsatisfactory because mortality was <15%. Soil temperature in this trial rose to 39 °C within 5 h after application. Nematodes failed in two other trials when soil temperature fell below freezing (minimum temperatures −3.0, −5.5 °C, respectively) several times in a 5-day period. We conclude that a commercially feasible application volume of 1870 L water/ha followed by post-application irrigation at this same rate was effective, and that soil maximum temperature at or below 32 °C during the first 24 h after application is necessary for treatment success.  相似文献   

14.
In this paper GC/MS-SCAN was used to identify the crude oil components that persist after bioremediation treatment of contaminated soil and the metabolites generated during this process. The soil was treated in bioreactors inoculated with an adapted bacterial population. In the first of two sets of conditions used, the water phase of the reactor was circulated continuously at a flow rate of 7 l day−1, and in the other case, it was circulated for a short period once a day to give the equivalent of 0.5 l day−1. Data showed that acyclic, n- and substituted alkanes C12 were still present after one year of remediation, while the majority of substituted derivatives of polycyclic and aromatic hydrocarbons could not be detected by GC/MS-SCAN analysis. The number of components identified was about one-half of that initially observed. After treatment the same number of components was detected at the top and bottom of the reactor in which the water phase was circulated continuously, whereas a smaller number of metabolites were observed at the top rather than at the bottom of the reactor with discontinuous circulation. The analysis has pointed to the importance of n-alkanes, their substituted derivatives and polycyclic aromatic hydrocarbons as the most significant pollutants.  相似文献   

15.
Fallen timber is an important component of many aquatic and terrestrial ecosystems around much of the world. Its distribution and abundance has been extensively altered, especially over the past 200 years. While correlative evidence suggests that many species require fallen timber for them to occupy locations, there are few precisely controlled field experiments that show conclusively how species respond to variation in loads. We manipulated wood loads (ranging from 0 to 80 Mg ha−1) and monitored the response over 6 years of a species of marsupial, the yellow-footed antechinus Antechinus flavipes. The antechinus appeared to prefer locations having fallen-timber loads 20 Mg ha−1. Antechinuses avoided bare areas (i.e. 0 Mg ha−1) and areas having finer forms of woody material. Changes in densities of the antechinus in excess of those occurring in the control plots were clear after 2 years following manipulation of loads, and were even more pronounced after almost 6 years. Therefore, we are confident that higher loads are favoured by the antechinuses. There was no evidence of breeding success by females in sites with 20 Mg ha−1, and that the highest, consistent breeding activity was achieved at sites with the greatest fallen-timber loads (80 Mg ha−1). Our results, which experimentally were designed to address responses to fallen-timber loads, were complicated by perturbations caused by managed flooding episodes of the experimental area. Flooding appears to lead to population booms of the antechinus, most probably related to irruptions of prey species such as carabid beetles and wolf spiders, which are large-bodied and are prey for the antechinus. Nevertheless, we show that there are differences in densities in different wood-load treatments even against a background of boom-and-bust dynamics associated with flooding.  相似文献   

16.
In this paper we study canonical RNA pseudoknot structures. We prove central limit theorems for the distributions of the arc-numbers of k-noncrossing RNA structures with given minimum stack-size τ over n nucleotides. Furthermore we compare the space of all canonical structures with canonical minimum free energy pseudoknot structures. Our results generalize the analysis of Schuster et al. obtained for RNA secondary structures [Hofacker, I.L., Schuster, P., Stadler, P.F., 1998. Combinatorics of RNA secondary structures. Discrete Appl. Math. 88, 207–237; Jin, E.Y., Reidys, C.M., 2007b. Central and local limit theorems for RNA structures. J. Theor. Biol. 250 (2008), 547–559; 2007a. Asymptotic enumeration of RNA structures with pseudoknots. Bull. Math. Biol., 70 (4), 951–970] to k-noncrossing RNA structures. Here k2 and τ are arbitrary natural numbers. We compare canonical pseudoknot structures to arbitrary structures and show that canonical pseudoknot structures exhibit significantly smaller exponential growth rates. We then compute the asymptotic distribution of their arc-numbers. Finally, we analyze how the minimum stack-size and crossing number factor into the distributions.  相似文献   

17.
Canna indica L. is an upright perennial rhizomatous herb, and Schoenoplectus validus (Vahl) A. Löve and D. Löve is a tall, perennial, herbaceous sedge. The nutrient uptake kinetics of C. indica and S. validus were investigated using the modified depletion method after plants were grown for 4 weeks in simulated secondary-treated wastewater. The maximum uptake rate (Imax) and Michaelis–Menten constant (Km) were estimated by iterative curve fitting. The Imax for NH4N (623 μmol g−1 dry root weight h−1) was significantly higher than that for NO3N (338 μmol g−1 dry root weight h−1) in S. validus. In contrast, no difference was observed in C. indica. The Imax values for NO3N and NH4N were higher in S. validus than in C. indica. A significantly lower Km was detected for NO3N uptake in C. indica (385 μmol L−1) compared to that in S. validus (1908 μmol L−1). The Imax for PO4P did not differ between the plant species. The Km for PO4P was significantly higher in C. indica (157 μmol L−1) than in S. validus (60 μmol L−1). In conclusion, we found that S. validus preferred NH4N over NO3N, had greater capacity for N uptake and higher affinity for PO4P, but C. indica had greater affinity for NO3N. Nutrient uptake capacity is likely related to habitat preference, and is influenced by the structure of roots and rhizomes.  相似文献   

18.
The kinetics of formation of the green manganate(VI) intermediate complex formed during the oxidation of pectin polysaccharide (poly galacturonate methyl ester) (PGME) by in alkaline solution at pH  12 have been studied. The rate law was suggested to be: rate = . The reaction was found to be base – catalyzed and fractional second – order in [PGME]. The activation parameters have been evaluated and discussed. A reaction mechanism was suggested according to the experimental data. A new blue hypomanganate(V) coordination polymer intermediate sol was spectrophotometrically detected for the first time for pectin (poly galacturonate methyl ester) oxidation reaction. A further mechanistic presentation was proposed.  相似文献   

19.
The serine/threonine kinases Plk1, Plk2, and Plk3 harbor a protein–protein interaction domain dubbed polo-box domain (PBD). Recently, the inhibition of the PBD of the cancer target Plk1 has been successfully explored as an alternative to the inhibition of the kinase by ATP-competitive ligands. However, because the PBDs of Plk1, Plk2, and Plk3 have very similar optimal binding motifs, absolute specificity for the PBD of Plk1 over the PBDs of Plk2 and Plk3 may also represent a big challenge for a small molecule. To aid in the activity profiling of Plk PBD inhibitors, and to identify selective small molecules that will reveal the cellular consequences of inhibiting the PBDs of Plk2 and Plk3, we have developed high-throughput assays based on fluorescence polarization against the PBDs of Plk2 and Plk3. The assays are stable with regard to time and 10% dimethyl sulfoxide and have Z′ values 0.7, making them well-suited for high-throughput screening. Moreover, our data provide insights into the binding preferences of the PBDs of Plk2 and Plk3.  相似文献   

20.
Standard maize starch was hydrothermally treated by Instantaneous Controlled Pressure Drop (DIC) process at three pressure levels (1, 2 and 3 bar) corresponding to the temperatures of 100, 122 and 135 °C (at 13–27% moisture), respectively. The structural effects of various hydrothermal conditions were examined with differential scanning calorimetry (DSC) and wide-angle X-ray diffraction. In order to understand the changes that occur during DIC treatment, melting endotherms of native maize starch at various moisture contents were determined. The gelatinization temperatures of DIC treated standard maize starch increased with DIC treatment. The transition temperatures (To, Tp) are closely related to the combined effect of pressure and processing time. At approximately 10 min of processing time, To and Tp were 65.7 and 72.3, 68.8 and 73.6 °C, 74.8 and 79.8 °C for pressure levels of 1, 2 and 3 bar, respectively (against 63.1 and 69.6 °C for native starch). DIC treatment narrowed the gelatinization temperature range and decreased gelatinization enthalpy (ΔH), as the severity of processing conditions increased. ΔH decreased from 11.4 J g−1 (native) to 11.0 (1 bar), 9.0 (2 bar) and 1.7 J g−1 (3 bar) for treated maize starch during approximately 10 min. Relative crystallinity of hydrothermally treated starch decreased with increasing DIC conditions. The A-type crystalline pattern was progressively lost (at pressure level 2 bar) and substituted by the Vh-type X-ray diffraction pattern, corresponding to the formation of amylose–lipid complexes. For severe DIC conditions (pressure level of 3 bar), the substitution was completed. Microscopic observations revealed progressive loss of the birefringence of DIC treated starch granules except at low pressure (1 bar), while the integrity of starch granules was preserved for all the conditions. These modifications that reveal important changes in the crystalline organization of the starch granules are related to their functional properties.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号