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1.
A glasshouse experiment was conducted to study the effect of Ni on the growth and nutrients concentration in wheat (Triticum aestivum Cv. WH 291) in the presence and absence of applied N as urea. Responses to N application were observed up to 120 g N g–1 soil. No response to Ni was observed in the dry matter yield of wheat tops (leaves + stem) in the absence of applied N while in the presence of applied N, significant yield increases were obtained at 12.5g Ni g–1 soil. Nickel was not toxic to wheat up to 50g Ni g–1 soil in the presence of 120g N g–1 soil. Nitrogen and Ni concentration in wheat tops and roots increased with increasing levels of applied N and Ni, respectively. Applied Ni had an antagonistic effect on N concentration. Similarly, N reduced the Ni concentration in the wheat tissues. Positive growth responses to Ni were associated with 22 and 15g Ni g–1 in wheat tops, in the presence of applied N at 60 and 120g N g–1 soil, while Ni toxicity was associated with 63, 92.5 and 112.5g Ni g–1 in wheat tops, in the absence and presence of applied N at 60 and 120g N g–1 soil, respectively.  相似文献   

2.
Bonanni  P.  Caprioli  R.  Ghiara  E.  Mignuzzi  C.  Orlandi  C.  Paganin  G.  Monti  A. 《Hydrobiologia》1992,235(1):553-568
The Orbetello lagoon is now highly eutrophic and has experienced increasing incidence of anoxia causing serious economic damage. A multidisciplinary study was commenced in March 1987 to investigate the part played by the lagoon sediments and interstitial water in recycling nutrients and contributing to the observed anoxia. Eleven undisturbed cores were collected and sub-sampled at 2 cm intervals. Interstitial water was obtained by centrifugation and analyzed for pH, Eh, nutrients, major and some minor elements. Differential fluxes from the sediments of 0.2–10 g cm–2 day–1 of ammonia and 0.02–0.7 g cm–2 day–1 of orthophosphate were obtained depending on the season, temperature of the sediments and the sampling location. A highly significant linear correlation (r 2 = 0.86) was found between bicarbonate and ammonia concentrations in the interstitial waters, due to the release of these compounds during the degradation organic matter. A diagenetic model was developed to predict the alkalinity of interstitial water from the theoretical reactions involved in the decomposition of organic matter. The predicted values for bicarbonate and ammonia agreed well with the experimental results.  相似文献   

3.
The effects of eight microelements (I, BO3 3–, MoO4 2–, Co2+, Cu2+, Mn2+, Fe2+, Zn2+) on the biosynthesis of camptothecin and the growth of suspension cultures of Camptotheca acuminata were studied. The increase of I to 25 M l–1, Cu2+ to 1 M l–1, Co2+ to 2 M l–1 and MoO4 2– to 10 M l–1 in Murashige and Skoog (MS) medium resulted in 1.66, 2.84, 2.53 and 2.04 times higher of camptothecin yield than that in standard MS medium respectively. Combined treatment of I (25 M l–1), Cu2+ (1 M l–1), Co2+ (2 M l–1) and MoO4 2– (10 M l–1) lead to improve cell dry weight, camptothecin content, and camptothecin yield to 30.56 g l–1, 0.0299%, and 9.15 mg l–1, respectively, which were 20.2, 208.9 and 273.8% increment respectively when compared with those of control.  相似文献   

4.
A 20–40 m pellicular high density (3.7 g cm–3) expanded bed material has been designed for the capture of DNA and other large macromolecules. Anion exchangers fashioned out of these supports exhibited dramatically enhanced DNA binding capacities over commercial anion exchange adsorbents (6 mg ml–1, c.f. 50 g ml–1 at 10% breakthrough), due to a combination of small particle and fuzzy surface architecture created through the coupling of polyethylene imine chains.  相似文献   

5.
Somatic embryogenesis in pigeonpea [Cajanus cajan (L.) Millsp.] has been achieved using cotyledon segments of mature seeds as explants. A large number of globular somatic embryos were induced directly from cotyledons of genotypes T-15-15, GAUT-82-90 and GAUT-82-99 when cultured on EC6 basal medium supplemented with 2.22, 4.44, 13.32 or 22.2 M N6-benzylaminopurine (BAP) and 0.45, 1.36, 2.27, 4.54 and 13.62 M thidiazuron. Somatic embryos developed into cotyledonary stage when the globular embryos were transferred to Murashige and Skoog's (MS) basal medium containing 2.89 – 14.43 M gibberellic acid. Maturation of somatic embryos was achieved on half strength MS medium with 0.38 M abscisic acid. The mature somatic embryos were germinated on MS medium supplemented with 0.44 M BAP and the plantlets were hardened and transferred to soil.  相似文献   

6.
Rusanov  I. I.  Lein  A. Yu.  Pimenov  N. V.  Yusupov  S. K.  Ivanov  M. V. 《Microbiology》2002,71(4):479-487
Seasonal investigations of methane distribution and rates of its oxidation and generation in the water column and sediments of the Black Sea northwestern shelf were carried out within the framework of the interdisciplinary projects European River–Ocean Systems (EROS-2000, EROS-21) and Biogenic Gases Exchange in the Black Sea (BigBlack) in August 1995, May 1997, and December 1999. Experiments that involved the addition of 14CH3COONa and 14CO2 to sediment samples showed the main part of methane to be formed from CO2. Maximum values of methane production (up to 559 mol/(m2 day)) were found in coastal sediments in summer time. In winter and spring, methane production in the same sediments did not exceed 3.6–4.2 mol/(m2 day). The 13C values of methane ranged from –70.7 to –81.8, demonstrating its microbial origin and contradicting the concept of the migration of methane from cold seeps or from the oil fields located on the Black Sea shelf. Experiments that involved the addition of 14CH4 to water and sediment samples showed that a considerable part of methane is oxidized in the upper horizons of bottom sediments and in the water column. Nevertheless, it was found that, in summer, part of the methane (from 6.8 to 320 mol/(m2 day)) arrives in the atmosphere.  相似文献   

7.
Savvichev  A. S.  Rusanov  I. I.  Yusupov  S. K.  Pimenov  N. V.  Lein  A. Yu.  Ivanov  M. V. 《Microbiology》2004,73(4):457-468
Microbiological and biogeochemical investigations of the processes of methane production (MP) and methane oxidation (MO) in the coastal waters and littoral of the Kandalaksha Bay of the White Sea were carried out. The studies were conducted in the coastal zones and in the water areas of the Kandalaksha Preserve, Moscow State University White Sea Biological Station, and the Zoological Institute (RAS) biological station in August 1999, 2000, and 2001 and in March 2001. The rate of CO2 assimilation in the shallow and littoral sediments was 35–27800 g C/(dm3 day) in summer and 32.8–88.9 g C/(dm3 day) in winter. The maximal rates of MP were observed in the littoral sediments in the zone of macrophyte decomposition, in local depressions, and in the estuary of a freshwater creek (up to 113 l/(dm3 day)). The maximal level of MO was observed in the shallow estuarine sediments (up to 2450 l/(dm3 day)). During the winter season, at the temperature of –0.5 to 0.5°C, the MP rate in the littoral sediments was 0.02–0.3 l/(dm3 day), while the MO rate was 0.06–0.7 l/(dm3 day). The isotopic data obtained indicate that the Corg of the mats and of the upper sediment layers is enriched with the heavy 13C isotope by 1–4 as compared to the Corg of the suspension. A striking difference was found between the levels of methane emission by the typical littoral microlandscapes. In fine sediments, the average emission was 675 l CH4/(m2 day); in stormy discharge stretch sediments, it was 1670 l CH4/(m2 day); and under stones and in silted pits, 1370 l CH4/(m2day). The calculation, performed with consideration of the microlandscape areas with a high production, allowed the CH4 production of 1 km2 of the littoral to be estimated as 192–300 l CH4/(km2 day).  相似文献   

8.
Adventitious shoot regeneration was observed using leaf-petiole explants from shoot-proliferating cultures of Comet red raspberry (Rubus idaeus L.). A maximum regeneration rate of 70% (3.7 shoots/explant) was obtained using 4.5–9.1 M (1–2 mg l–1) N-phenyl-N-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ) with 2.5–4.9 M (0.5–1 mg l–1) 1H-indole-3-butanoic acid (IBA) or 2.3 M (0.5 mg l–1) TDZ with 4.9 M (1 mg l–1) IBA in modified Murashige-Skoog medium. TDZ was more effective than N-(phenylmethyl)-1H-purin-6-amine (BA) at promoting regeneration in combinations tested with IBA (maximum 50% regeneration rate; 1.8 shoots/explant). Variation in the agar concentration or incubation temperature, orientation or scoring of the leaf-petiole explants and use of separate leaf or petiole explants had no effect on shoot regeneration. Incubation in the dark for 1, 2 or 3 weeks prior to growth in the light did not influence the percent regeneration rate but depressed the number of adventitious shoots. Explant source, from micropropagated shoots or greenhouse-grown plants, had an effect on shoot regeneration that was genotype dependent. Only 8 of 22 (36%) raspberry cultivars were capable of regeneration from leaf explants derived from greenhouse-grown plants.  相似文献   

9.
We studied the effect of triacontanol (TRIA) on shoot multiplication and rooting of in vitro derived shoot tips of Capsicum frutescens and Decalepis hamiltonii W & A. In both shoot multiplication and rooting phases, TRIA was administered at 2-20 g l–1. TRIA resulted in highest promotion of axillary shoot proliferation at 2 g l–1 in Capsicum frutescens and 20 g l–1 in Decalepis hamiltonii while rooting was maximum at 5 and 10 g l–1 for Capsicum frutescens and Decalepis hamiltonii respectively. TRIA enhanced shoot growth and chlorophyll content of leaves and also influenced root induction and supported growth of the roots. This work reveals that TRIA can be used as an effective growth regulator in the micropropagation of Capsicum frutescens and Decalepis hamiltonii, an endangered shrub of Deccan peninsular India.  相似文献   

10.
Biochemical and biophysical parameters, including D1-protein turnover, chlorophyll fluorescence, oxygen evolution activity and zeaxanthin formation were measured in the marine seagrassZostera capricorni (Aschers) in response to limiting (100 mol·m–2·–1), saturating (350 mol·m–2·s–1) or photoinhibitory (1100 mol·m–2·s–1) irradiances. Synthesis of D1 was maximal at 350 mol·m–2·s–1 which was also the irradiance at which the rate of photosynthetic O2 evolution was maximal. Degradation of D1 was saturated at 350 mol·m–2·s–1. The rate of D1 synthesis at 1100 mol·m–2·s–1 was very similar to that at 350 mol·m–2·s–1 for the first 90 min but then declined. At limiting or saturating irradiance little change was observed in the ratio of variable to maximal fluorescence (Fv/Fm) measured after dark adaptation of the leaves, while significant photoinhibition occurred at 1100 mol·m–2·s–1. The proportion of zeaxanthin in the total xanthophyll pool increased with increasing irradiance, indicative of the presence of a photoprotective xanthophyll cycle in this seagrass. These results are consistent with a high level of regulatory D1 turnover inZostera under non-photoinhibitory irradiance conditions, as has been found previously for terrestrial plants.We would like to thank Professor Peter Böger (Department of Plant Biochemistry, University of Konstanz, Germany) for the kind gift of D1 antibodies. This work was partly supported by a University of Queensland Enabling Grant to CC.  相似文献   

11.
Water, suspended particulate matter (SPM) and sediments were collected from the Esteiro de Estarreja (Ria de Aveiro, Portugal), which receives considerable quantities of waste mercury from a chlor-alkali plant. Dissolved and particulate Hg concentrations in the effluent ranged between 4 –167 g I–1 and 141–3144 g g–1, respectively, at pH values of >10. The effluent plume undergoes significant chemical changes during advection downestuary. The evidence suggested that adsorption of dissolved Hg onto organic-rich SPM was an important process. A maximum sediment Hg concentration of 500 g g–1 was found about 1.5 km from the discharge, as a result of the settling of Hg-rich SPM. Downestuary Hg concentrations in sediments decline to about 100 g g–1 at the mouth of the Esteiro. The particle-water interactions are discussed in terms of the transport of dissolved and particulate Hg into the Ria de Aveiro.  相似文献   

12.
Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10-2 mol l–1, gibberellic acid (GA3) 3.10-2 mol l–1, and 6-benzylaminopurine (BA) 2 mol l–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l–1, GA3 14 mol l–1, and kinetin 5 mol l–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l–1 and BA 10 mol l–1 was induced.Abbreviations BA 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA3 gibberellic acid - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - TEM transmission electron microscopy  相似文献   

13.
A comparison has been made of cyclopropene (CP), 1-methylcyclopropene (1-MCP), and 3,3-dimethyl-cyclopropene (3,3-DMCP) in their ability to protect plants against ethylene. In bananas, both CP and 1-MCP are effective around 0.5 nL L–1, and 3,3-DMCP was effective at 1 L L–1. Bananas treated with CP and 1-MCP again become sensitive to ethylene at 12 days and those treated with 3,3-DMCP at 7 days. Mature green tomatoes are protected by 5–7 nL L–1 of 1-MPC for 8 days at 25°C and tomatoes treated with 3,3-DMCP at 5–10 L L–1 are protected for 5 days. Carnation flowers are protected with CP or 1-MCP after exposure to 0.5 nL L–1 for 24 hours and by 1 L L–1 of 3,3-DMCP. The display life of Campanula flowers is increased from 3.3 to 5.4 days by 10 L L–1 of 3,3-DMCP and to 9 days by 20 nL L–1 of 1-MCP. Ethylene inhibition of pea seedlings is reduced by treatment with 1-MCP at 10 L L–1 of ethylene but as ethylene is increased to 3000 L L–1 growth inhibition increases. 3,3-DMCP treatment causes very little reduction of the ethylene effect even at very low concentrations.  相似文献   

14.
This study addresses the temporal distribution of forms of phosphorus in the soil of a temporarily flooded riparian forest of the valley of the river Garonne (Southwest of France). A sequential extraction for forms of phosphorus of increasing chemical stability was used. During the study period (13 months), the forest was flooded a few days during March and May. In winter, resin-Pi concentration was high (26 g g–1) in comparison to spring values (<9 g g–1). NaHCO3-Po, NaHCO3-Pi or NaOH-Pi concentrations increased during winter (up to 74, 124 and 78 g g–1 respectively) and decreased significantly during spring (32, 44 and 32 g g–1 respectively). This pattern was attributed to simultaneous mineralization and plant uptake during the growing season and to the flood events (erosional processes and P-release). During summer and fall, resin-Pi concentration increased significantly (up to 26 g g–1 in October). NaHCO3-Po concentrations remained low during spring and summer (<33 g g–1), and increased significantly in fall (>45 g g–1 NaHCO3-Pi or NaOH-Pi increased in late spring or summer (90 g g–1 and 68 g g–1 respectively). Increasing concentrations of the labile forms during late spring or summer were ascribed to the warm temperature and soil dryness that limited plant growth. HCl-Pi increased regularly after the floods (174 g g–1 before the flood events to 254 g g–1 after the floods). Residual P presented a similar pattern i.e. 214 g g–1 and 279 g g–1 respectively before and after the flood events. This pattern was attributed to a progressive incorporation of flood deposits to the soil.  相似文献   

15.
Although ergogenic effects and health benefits have been reported for creatine used as nutritional supplement, to date little is known about the mechanism of creatine absorption in the small intestine. Thus the current study was undertaken to elucidate the mechanism of creatine intake in rat jejunum with the use of well-purified brush border membrane vesicles, isolated from jejunal enterocyte. Creatine uptake was found markedly stimulated by inwardly directed Na+ and Clgradients, potential-sensitive, strongly reduced by the substitution of Na+ and Cl with various cations and anions and positively affected by intravesicular K+. Moreover, creatine uptake is: 1) significantly inhibited by creatine stuctural analogs, 2) abolished by low concentrations of 2-aminoethyl methanethiosulfonate hydrobromide (MTSEA), 3) saturable as a function of creatine concentration with an apparent Michaelis-Menten constant of 24.08±0.80 M and a maximal velocity of 391.30±6.19 pmoles mg protein–1 30 s–1. The transport is electrogenic since at least two Na+ and one Cl are required to transport one creatine molecule. Western blot analysis showed the same amount of creatine transport protein in the jejunal apical membrane when compared to ileum. Thus, these data demonstrate the existence of a Na+- and Cl-dependent, membrane potential-sensitive, electrogenic carrier-mediated mechanism for creatine absorption in rat jejunal apical membrane vesicles, which is biochemically and pharmacologically similar to those observed in other tissues. However, in other cell types the stimulatory effect of intravesicular K+ was never detected.  相似文献   

16.
Uptake kinetics of nitrogen derived from sewage–seawater mixtures (2.5–20% v/v effluent) were determined in the laboratory for Ulva rigida (Chlorophyceae) native from Bahía Nueva (Golfo Nuevo, Patagonia, Argentine). In terms of nitrogen concentration, experimental enrichment levels varied between 53.7 and 362.3M of ammonium and between 0.77 and 6.21M of nitrate+nitrite. Uptake rates were fitted to the Michaelis–Menten equation, with the following kinetic parameters: ammonium: Vmax = 591.2molg–1h–1, K s=262.3M, nitrate+nitrite: V max=12.9molg–1h–1, K s=3.5M). Both nutrients were taken up simultaneously, but ammonium incorporation was faster in all cases. The results show a high capability of Ulva rigida to remove sewage-derived nitrogen from culture media. In the field, most of the nitrogen provided by the effluent would be tied up in algal biomass, supporting low nitrogen levels found at a short distance away from the source.  相似文献   

17.
George  T.S.  Gregory  P.J.  Robinson  J.S.  Buresh  R.J. 《Plant and Soil》2002,246(1):65-73
The aim of this work was to assess whether agroforestry species have the ability to acquire P from pools unavailable to maize. Tithonia diversifolia(Hemsley) A. Gray, Tephrosia vogelii Hook f., Zea mays and Lupinus albusL. were grown in rhizopots and pH change and depletion of inorganic and organic P pools measured in the rhizosphere. Plants were harvested at the same growth stage, after 56 days for maize and white lupin and 70 days for tithonia and tephrosia, and the rhizosphere sampled. The rhizosphere was acidified by tithonia (pH change –0.3 units to pH 4.8) and lupins (–0.2 units to 4.9), alkalinised by tephrosia (+0.4 units to pH 5.4), and remained unchanged with maize growth. Concurrent with acidification in the rhizosphere of tithonia there was a decline in resin-P (0.8 g P g–1). However, there was also a decline in NaOH extractable inorganic P (NaOH-Pi) (5.6 g P g–1 at the root surface) and organic P pools (NaOH-Po) (15.4 g P g–1 at 1.5 mm from the root), which would not be expected without specific P acquisition mechanisms. Alkalinisation of tephrosia rhizosphere was accompanied by changes in all measured pools, although the large depletion of organic P (21.6 g P g–1 at 5 mm from the root) suggests that mineralisation, as well as desorption of organic P, was stimulated. The size of changes of both pH and P pools varied with distance away from the rhizoplane. Decline of more recalcitrant P pools with the growth of the agroforestry species contrasted with the effect of maize growth, which was negligible on resin-P and NaOH-Pi, but led to an accumulation of P as NaOH-Po (14.2 g P g–1 at 5 mm from the root). Overall the depletion of recalcitrant P pools, particularly Po, suggests that the growth of tithonia and tephrosia enhance desorption and dissolution of P, while also enhancing organic P mineralisation. Both species appear to have potential for agroforestry technologies designed to enhance the availability of P to crops, at least in the short term.  相似文献   

18.
The effects of a 60 min exposure to photosynthetic photon flux densities ranging from 300 to 2200 mol m–2s–1 on the photosynthetic light response curve and on PS II heterogeneity as reflected in chlorophyll a fluorescence were investigated using the unicellular green alga Chlamydomonas reinhardtii. It was established that exposure to high light acts at three different regulatory or inhibitory levels; 1) regulation occurs from 300 to 780 mol m–2s–1 where total amount of PS II centers and the shape of the light response curve is not significantly changed, 2) a first photoinhibitory range above 780 up to 1600 mol m–2s–1 where a progressive inhibition of the quantum yield and the rate of bending (convexity) of the light response curve can be related to the loss of QB-reducing centers and 3) a second photoinhibitory range above 1600 mol m–2s–1 where the rate of light saturated photosynthesis also decreases and convexity reaches zero. This was related to a particularly large decrease in PS II centers and a large increase in spill-over in energy to PS I.Abbreviations Chl chlorophyll - DCMU 3,(3,4-dichlorophenyl)-1,1-dimethylurea - FM maximal fluorescence yield - Fpl intermediate fluorescence yield plateau level - F0 non-variable fluorescence yield - Fv total variable fluorescence yield (FM-F0) - initial slope to the light response curve, used as an estimate of initial quantum yield - convexity (rate of bending) of the light response curve of photosynthesis - LHC light-harvesting complex - Pmax maximum rate of photosynthesis - PQ plastoquinone - Q photosynthetically active photon flux density (400–700 nm, mol m–2s–1) - PS photosystem - QA and QB primary and secondary quinone electron acceptor of PS II  相似文献   

19.
Wheat for human consumption (140 samples) was collected after harvest from all regions of Bulgaria. The 1995 crop year was characterized by heavy rainfall in the spring and summer months. The internal mycoflora of wheat samples was dominated by Fusarium spp. and Alternaria spp., and storage fungi were rarely present. The samples were analysed for contamination with Fusarium mycotoxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), and zearalenone (ZEA), using enzyme immunoassay methods. DON and ZEA were the predominant toxins, with a contamination frequency of 67% and 69%, respectively. The average levels of these toxins in positive samples were 180 g/kg (DON) and 17 g/kg (ZEA), maximum concentrations were 1800 g kg–1 and 120 g kg–1, respectively. Acetyl derivatives of DON, namely 3-AcDON and 15-AcDON, were found in 2.1 % and 0.7% of the samples, at at maximum level of about 100 g kg–1. Only one sample was positive for T-2 (55 g/kg), DAS was not detected. This is the first report about the natural occurrence of a range of Fusarium mycotoxins in wheat for human consumption in Bulgaria.Abbreviations 3-AcDON 3-acetyldeoxynivalenol - 15-AcDON 15-acetyldeoxynivalenol - DAS diacetoxyscirpenol - DON deoxynivalenol - EIA enzyme immunoassay - T-2 T-2 toxin - ZEA zearalenone  相似文献   

20.
Efficient micropropagation, callus culture and root culture protocols were developed for the medicinal plant Phyllanthus urinaria(Euphorbiaceae) using single node explants. Maximum multiplication (16–20 shoots per explant) was achieved on Murashige and Skoog media supplemented with 5.0 M kinetin. Murashige and Skoog and Anderson Rhododendron media promoted significant shoot culture growth in terms of numbers of shoots and nodes produced per explant. Rooting was achieved with 93–100% of the microshoots on Murashige and Skoog medium without growth regulators, although 1.25–5.0 M -naphthaleneacetic acid significantly increased the number of roots per explant. Regenerated plants were successfully acclimatized and 91% of plantlets survived under ex vitro conditions. Flowering was observed on micropropagated plants after 3–4 weeks of acclimatization. High frequency callus initiation and growth was achieved when single node explants were inoculated in the horizontal position on Murashige and Skoog medium supplemented with 5.0 M indole-3-butyric acid. Other auxins such as 2,4-dichlorophenoxyacetic acid and -naphthaleneacetic acid promoted moderate callus fresh weight increase, when used separately. Root cultures were successfully established on Murashige and Skoog medium containing 1.1 M -naphthaleneacetic acid. The optimized micropropagation, callus culture and root culture protocols offer the possibility to use cell/root culture techniques for vegetative propagation and secondary metabolism studies.  相似文献   

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