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991.
Elser James J.; Elser Monica M.; Carpenter Stephen R. 《Journal of plankton research》1986,8(2):365-383
Algal chlorophyll, carbon fixation and alkaline phosphataseactivity were net-fractionated using 22-µm, and 75-µmscreens in three lakes with contrasting zooplankton communities.Size distributions of algal biovolume were also determined throughmicroscopic examination. Relatively good correspondence wasfound between size distributions obtained through net fractionationand those determined by microscopic examination. Biovolume-specificcarbon fixation and chlorophyll decreased with increasing fractionsize but no differences were observed among fractions for chlorophyll-specificcarbon fixation. High algal standing stocks and low phosphorusdeficiency in Tuesday Lake were attributed to low grazing pressureby small, inefficient zooplankton and possible limitation bynutrients other than phosphorus. Algal standing stocks werelow and phosphorus deficiency was high in Peter and Paul Lakes,in which the zooplankton was dominated by large grazers. Differentalgal size fractions experienced differing degrees of phosphorusdeficiency. These size fraction differences in P-deficiencyin Peter and Paul Lakes were attributed to differences in algalspecies composition and to differing levels of zooplankton grazingpressure and nutrient regeneration. A unimodal relationshipbetween relative nanoplankton biovolume and zooplankton biomasswas found and reflects the positive (nutrient regeneration)and negative (grazing mortality) effects of zooplankton on thealgal community. 相似文献
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John Law Juan Jovel Jordan Patterson Glenn Ford Sandra O’keefe Weiwei Wang Bo Meng Deyong Song Yong Zhang Zhijian Tian Shawn T. Wasilenko Mandana Rahbari Troy Mitchell Tracy Jordan Eric Carpenter Andrew L. Mason Gane Ka-Shu Wong 《PloS one》2013,8(4)
We conducted an unbiased metagenomics survey using plasma from patients with chronic hepatitis B, chronic hepatitis C, autoimmune hepatitis (AIH), non-alcoholic steatohepatitis (NASH), and patients without liver disease (control). RNA and DNA libraries were sequenced from plasma filtrates enriched in viral particles to catalog virus populations. Hepatitis viruses were readily detected at high coverage in patients with chronic viral hepatitis B and C, but only a limited number of sequences resembling other viruses were found. The exception was a library from a patient diagnosed with hepatitis C virus (HCV) infection that contained multiple sequences matching GB virus C (GBV-C). Abundant GBV-C reads were also found in plasma from patients with AIH, whereas Torque teno virus (TTV) was found at high frequency in samples from patients with AIH and NASH. After taxonomic classification of sequences by BLASTn, a substantial fraction in each library, ranging from 35% to 76%, remained unclassified. These unknown sequences were assembled into scaffolds along with virus, phage and endogenous retrovirus sequences and then analyzed by BLASTx against the non-redundant protein database. Nearly the full genome of a heretofore-unknown circovirus was assembled and many scaffolds that encoded proteins with similarity to plant, insect and mammalian viruses. The presence of this novel circovirus was confirmed by PCR. BLASTx also identified many polypeptides resembling nucleo-cytoplasmic large DNA viruses (NCLDV) proteins. We re-evaluated these alignments with a profile hidden Markov method, HHblits, and observed inconsistencies in the target proteins reported by the different algorithms. This suggests that sequence alignments are insufficient to identify NCLDV proteins, especially when these alignments are only to small portions of the target protein. Nevertheless, we have now established a reliable protocol for the identification of viruses in plasma that can also be adapted to other patient samples such as urine, bile, saliva and other body fluids. 相似文献
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An immunofluorescence protocol for intracellular antigens of phytoplankton was developed empirically. Paraformaldehyde (4%) was used to fix samples for 6 h at 4° C; fixed samples can be stored in cold (–20°C) methanol for at least 1 month. We used Triton X-100, Nonidet P-40, and dimethyl sulfoxide to permeabilize the cells for antibody penetration across the cell wall and plasma membrane. After immunolabeling at room temperature, the samples were mounted on slides and could be stored at 4° C for up to 6 months without significant decay of the fluorescence. The staining was examined with an epifluorescence microscope; semiquantitative (percentage of cells with positive staining) and quantitative (staining intensity measured with an imaging system) analyses were performed. Reproducible staining was achieved for nuclear, chloroplastic, cytoplasmic, and cell surface antigens in species of Chlorophyceae, Prymnesiophyceae, Bacillariophyceae, and Dinophyceae including some field-collected samples. This protocol is advantageous to previously published protocols in that it allows relatively simple and long-term storage of fixed samples and allows staining of multiple antigens for the same sample. Although improvement on cell permeabilization is required for some species, the present protocol could prove useful for physiological or ecological studies when frequent sampling is required and immediate processing of the samples is not possible. 相似文献
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Beth A. Polidoro Kent E. Carpenter Lorna Collins Norman C. Duke Aaron M. Ellison Joanna C. Ellison Elizabeth J. Farnsworth Edwino S. Fernando Kandasamy Kathiresan Nico E. Koedam Suzanne R. Livingstone Toyohiko Miyagi Gregg E. Moore Vien Ngoc Nam Jin Eong Ong Jurgenne H. Primavera Severino G. Salmo III Jonnell C. Sanciangco Sukristijono Sukardjo Yamin Wang Jean Wan Hong Yong 《PloS one》2010,5(4)
Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the 70 known species of mangroves. Each species'' probability of extinction was assessed under the Categories and Criteria of the IUCN Red List of Threatened Species. Eleven of the 70 mangrove species (16%) are at elevated threat of extinction. Particular areas of geographical concern include the Atlantic and Pacific coasts of Central America, where as many as 40% of mangroves species present are threatened with extinction. Across the globe, mangrove species found primarily in the high intertidal and upstream estuarine zones, which often have specific freshwater requirements and patchy distributions, are the most threatened because they are often the first cleared for development of aquaculture and agriculture. The loss of mangrove species will have devastating economic and environmental consequences for coastal communities, especially in those areas with low mangrove diversity and high mangrove area or species loss. Several species at high risk of extinction may disappear well before the next decade if existing protective measures are not enforced. 相似文献
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