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排序方式: 共有814条查询结果,搜索用时 15 毫秒
51.
R. M. Flores-Rangel P. F. Rodríguez-Espinosa J. A. Montes de Oca-Valero V. Mugica-Alvarez M. E. Ortiz-Romero-Vargas M. Navarrete-Lopez 《人类与生态风险评估》2007,13(6):1359-1372
With the aim to know possible risks to the population, Cd, Co, Cr, Cu, Mn, Ni, Pb, and Tl were determined for the first time in airborne samples of particulate matter in an urban zone in Tampico, México, during the winter of 2003. The 24-hour PM10 samples were collected every 6 days on quartz-filters by using a high volume sampler and analyzed by Inductively Coupled Plasma Optical Emission Spectrometer. Standard reference material was used to verify metal recovery. The maximum PM10 and lead concentrations were 12.05 and 0.040 μ g/m3, respectively, not exceeding Méxican standard values. The greatest metal concentration was that of manganese with 0.90 μ g/m3, followed by Cu and Ni with 0.17 and 0.012 μ g/m3, respectively. Agglomerates, well-defined particles, and heavy metals (e.g., Mn and Cu) were found in PM10 using Scanning Electron Microscopy and Energy Dispersive Spectroscopy. Meteorological conditions associated with the sampling period showed that Pb and Ni are being continuously emitted, and that Mn, Cu, and Co could come from one industry located to the WSW of the region. All of these concentrations do not constitute a potential risk to human health, although it is necessary to continue studying the high concentrations of Mn and Cu in longer sampling periods. 相似文献
52.
Omotayo Sarafadeen Amuda Olumuyiwa Idowu Ojo Theresa Ibibia Edewor 《Bioremediation Journal》2007,11(4):183-194
The shell of the seed of Chrysophyllum albidum carbon was used to adsorb lead (Pb) from aqueous solution, the sorption process with respect to its equilibria and kinetics as well as the effects of pH, contact time, adsorbent mass, adsorbate concentration, and particle size on adsorption were also studied. The most effective pH range was found to be between 4.5 and 5 for the sorption of the metal ion. The first-order rate equation by Lagergren was tested on the kinetic data and the adsorption process followed first-order rate kinetics. Isotherm data were analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherms; the Freundlich and Langmuir models for dynamics of metal ion uptake proposed in this work fitted the experimental data reasonably well. However, equilibrium sorption data were better represented by Langmuir model than Freundlich. The adsorption capacity calculated from Langmuir isotherm was 72.1 mg Pb (II) g- 1 at initial pH of 5.0 at 30°C for the particle size of 1.00 to 1.25 mm with the use of 2.0 g/100 ml adsorbent mass. The structural features of the adsorbent were characterized by Fourier transform infrared (FTIR) spectrometry; the presence of hydroxyl, carbonyl, amide, and phosphate groups confirms the potential mechanism adsorption of the adsorbent. This readily available adsorbent is efficient in the uptake of Pb (II) ion in aqueous solution, thus, it could be an excellent alternative for the removal of heavy metals and organic matter from water and wastewater. 相似文献
53.
The effects of pectin from the eelgrass Zostera marina on toxic liver injury induced by enteral administration of lead acetate are examined in experiments on rats. The results show that pectin helps to rapidly reduce lead concentration in liver, to decrease lipid peroxidation, and to normalize the levels of total cholesterol and triglycerides in blood serum and liver. 相似文献
54.
Proietti R Lombardi L Quaglia C Sagone A 《Indian pacing and electrophysiology journal》2011,11(5):145-148
There is a general consensus that once a part of an implanted cardiac device becomes infected, it is usually impossible to cure the infection without completely removing all prosthetic material from the body. Consequently the Heart Rhythm Society (HRS) included the pocket infection or erosion as a class I indication for pacemaker lead exctraction. However, the procedure still carries a high risk of life-threatening complications due to fibrotic attachments between leads, veins, valves or other endocardial structures, notwithstanding specific tools and techniques that have been developed to assist the lead removal, preventing tissue laceration. 相似文献
55.
本试验研究了鳞毛蕨科两种植物革叶耳蕨(Polystichum neolobatum)和黑足鳞毛蕨(Dryopteris fuscipes)在不同浓度Cd-Pb复合胁迫下保护酶活性的变化。结果表明,革叶耳蕨POD、SOD、CAT活性与处理浓度呈正相关趋势,即随着处理浓度升高,酶活性明显升高;黑足鳞毛蕨POD、SOD及CAT活性表现出在高浓度(600+1200 mg/kg)处理下受抑制,而在低、中浓度(200+400 mg/kg、400+800 mg/kg)处理下表现为促进作用。 相似文献
56.
57.
The effects of environmental lead on the immune system of young children were assessed by determining the peripheral blood
lymphocytes CD3+, CD4+, CD8+, B(CD19+) counts, and natural killer (CD16+ CD56+) cells in 35 preschool children whose mean blood lead level was 140.6 μg/L. The results were compared to an age- and sex-matched
control group with a mean blood lead level of 64.3 μg/L. Compared to the controls, a significant reduction in the percentage
of CD4+ cells and a significant increase of CD8+ cells were seen in the high-lead group. The negative correlation between the percentage of CD4+ cells and blood lead levels was found to be significant (p<0.01). These results suggest that exposure to environmental lead might result in alterations in the immune function of young
children. 相似文献
58.
González-Reimers E Arnay-de-la-Rosa M Velasco-Vázquez J Galindo-Martín L Santolaria-Fernández F 《Biological trace element research》2005,105(1-3):37-51
This study was performed to determine the levels of lead (Pb) and cadmium (Cd) in 63 bone samples of the prehispanic population
of the island El Hierro, comparing them with the values obtained on 98 prehispanic samples from Tenerife, Fuerteventura, Gran
Canaria, and La Palma, all of them in the Canary Islands, and with eight modern samples who served as controls. Prehispanic
individuals from El Hierro showed the lowest bone Pb values of all the archipelago (0.72±1.01 mg/kg), significantly different
(F=6.9, p<0.001) from the values obtained for the population of other islands such as Tenerife (4.87±5.36 mg/kg) or Fuerteventura (4.45±7.85
mg/kg) and also from those of the modern population (30.53±14.62 mg/kg). On the other hand, bone Cd, although slightly lower
in the ancient population groups, was not significantly different when compared with the modern one. In addition, no differences
were observed in bone Cd among the ancient population of the different islands. Bone lead—but not cadmium—kept an inverse
significant relationship with the distance of the burial site both to south Spain (r=−0.31) and Atlantic Morocco (r=−0.28, p<0.001 in both cases). 相似文献
59.
Two novel metal-organic hybrid coordination polymers {[Cu(bpo)(chdc)(H2O)](H2O)0.5}n (1) and [Pb(chdc)(H2O)]n (2) have been synthesized under different conditions and structurally characterized by single-crystal X-ray diffraction technique, where H2chdc refers to a flexible 1,4-cyclohexanedicarboxylic acid ligand and bpo is 2,5-bis(4-pyridyl)-1,3,4-oxadiazole. Complex 1 has a two-dimensional (2-D) grid-like [11.28 × 13.63 Å2] framework in which the CuII centers are extended via bidentate bridging ligands bpo and e,e-trans-chdc along two directions, exhibiting large porous cavities. Coordination polymer 2 represents the first PbII complex of H2chdc in which the larger PbII centers are connected by e,a-cis-chdc anions to afford a 2-D close-knit structure. 相似文献
60.
This study addresses the impact of small-scale gold mining on the environment and communities of the Puyango River basin in
the southwest of Ecuador between 1999 and 2001. Our primary objectives were to measure mercury, manganese, and lead in the
river, to identify pathways of population exposure, and biological indicators of human exposure. A multi-method design at
the catchment scale was applied to the analysis of water, sediments, and particulate matter for mercury, lead, and manganese
over two different seasons. A household survey was undertaken, and individuals were assessed for lead (blood samples), and
for mercury (urine and hair samples). River water samples had high concentrations of particulate matter (700 mg/L). Mercury
and lead levels in water at the gold processing plants were very high in both seasons (250 ng Hg/L and 160 μg Pb/L). Mercury
and lead, there was a downstream gradient with the areas adjacent to the gold processing plants having the highest levels.
In Portovelo, the Upper Basin city, 14% of the population reported occupational exposure to inorganic mercury. Although no
one in Portovelo consumes water from the river, 10% of the population consume local fish. This contrasts the Lower Basin where
98% of the population consume fish, and 100% use river water for drinking and cooking. Lead blood levels over 20 μg/dl were
found in 39.4% of the study population and blood mercury over 10 μg/L only in 10.0%. Urinary mercury over 4 μg/L was found
in 66.5% of the examined persons. Hair methylmercury did not exceed the safe limit of 2 μg/g, the mean concentration was 1.2 μg/g.
Mining activity and erosion contributes to heavy-metal contamination (mercury, lead, and manganese) throughout the Puyango
Basin. The relation between environmental contamination is complex and further research is being conducted to understand these
relations. 相似文献