全文获取类型
收费全文 | 3232篇 |
免费 | 204篇 |
国内免费 | 1篇 |
出版年
2024年 | 5篇 |
2023年 | 31篇 |
2022年 | 54篇 |
2021年 | 124篇 |
2020年 | 78篇 |
2019年 | 92篇 |
2018年 | 106篇 |
2017年 | 88篇 |
2016年 | 120篇 |
2015年 | 204篇 |
2014年 | 197篇 |
2013年 | 250篇 |
2012年 | 281篇 |
2011年 | 263篇 |
2010年 | 168篇 |
2009年 | 143篇 |
2008年 | 160篇 |
2007年 | 190篇 |
2006年 | 171篇 |
2005年 | 152篇 |
2004年 | 148篇 |
2003年 | 105篇 |
2002年 | 95篇 |
2001年 | 26篇 |
2000年 | 19篇 |
1999年 | 18篇 |
1998年 | 28篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 15篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1978年 | 8篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有3437条查询结果,搜索用时 296 毫秒
991.
992.
993.
Gabriela Ibáñez-Cervantes Alejandro Martínez-Ibarra Benjamín Nogueda-Torres Eduardo López-Orduña Ana L. Alonso Cynthia Perea Teresa Maldonado José Manuel Hernández Gloria León-Avila 《Parasitology international》2013,62(1):36-43
Triatomine vectors were collected on human dwellings in Michoacán México. Blood meal sources were identified by real time polymerase chain reaction (Q-PCR) using DNA extracted from triatomine guts. The assay was performed with one only specific primer set to amplify a fragment of the mitochondrial 12S ribosomal gene from vertebrate species. Also Trypanosoma cruzi parasites were detected in triatomine gut samples by microscopy and the positive infection was tested in mice. In addition T. cruzi discrete taxonomic units (DTUs) were identified by Q-PCR with two sets of primers that amplify the mini-circle region (miniexon) and 18S ribosomal mitochondrial gene. The sequences obtained from 18S ribosomal gene amplifications confirmed the presence of T. cruzi I and II lineages, and provide evidence of the presence of lineage TcIII and TcIV. 相似文献
994.
Francisc Péter Claudia Kiss Emese Szocs-Bíró Gabriela Preda Cristina Zarcula 《Biocatalysis and Biotransformation》2013,31(3-4):251-260
Sol-gel entrapment of microbial lipases from Candida cylindracea (Cc lipase),Pseudomonas fluorescens (Lipase AK), and Pseudomonas cepacia (Lipase PS), using as precursors tetraethoxysilane (TEOS) and silanes of type R-Si(OEt)3 with alkyl or aryl R groups, has been investigated. Three different methods using these precursors were tried exhibiting protein immobilization yields in the range of 20–50%. Hydrolysis of emulsified olive oil, esterification of lauric acid with 1-octanol and enantioselective acylation of 2-pentanol have been used as model reactions for testing the properties of the encapsulated lipases. The recovery yields of the enzyme activity in the esterification reaction were between 20–68%, the best performance being achieved with phenyltriethoxysilane and tetraethoxysilane precursors at 3:1 molar ratio. When testing the entrapped Lipase AK in the enantioselective acylation reaction of 2-pentanol, activity recovery yields up to 32% related to the free enzyme were obtained and the immobilization increased the enantioselectivity of the enzyme. 相似文献
995.
996.
AbstractThe lower Paleozoic marine siliciclastic succession of the Central Andean Basin, northwestern Argentina, provides a valuable record of the onset of the Great Ordovician Biodiversification Event in western Gondwana. A new ichnospecies of rosette trace fossil, Gyrophyllites cristinae, is documented from lower and upper Tremadocian (Tr1 and Tr2) deposits of this basin. It is characterized by five to six non-overlapping petaloid lobes and can be easily differentiated from the other four formally defined ichnospecies. Gyrophyllites cristinae occurs at the top of hummocky cross-stratified sandstone regularly interbedded with mudstone. These deposits are interpreted as reflecting the alternation of high-energy storm events and low-energy fair-weather conditions immediately below the fair-weather wave base, representing deposition in offshore transition environments. Gyrophyllites has been traditionally interpreted as the product of worms of uncertain taxonomic affinity that mined the sediment in search for food (fodinichnia). The occurrence of Gyrophyllites cristinae in these Ordovician deposits records post-storm colonization. Storms may have increased oxygenation and supplied fresh organic detritus that were exploited by worm-like, surface detritus- or shallow deposit-feeders exploring the uppermost silt-rich fine-grained sediments. 相似文献
997.
Rosa Gabriela Beltrán-López Omar Domínguez-Domínguez Kyle R. Piller Humberto Mejía-Mojica Adán Fernando Mar-Silva Ignacio Doadrio 《Journal of fish biology》2021,98(5):1253-1266
Central Mexico is characterized by a complex topography that is the result of historic and contemporary tectonic and climatic factors. These events have influenced the evolutionary history of numerous freshwater fishes in the region. Nonetheless, recent studies have shown that life-history traits and ecological characteristics of species may influence dispersal capabilities and the degree of genetic connectivity. Goodea (Cyprinodontiformes: Goodeidae) is one of the most widely distributed and environmentally tolerant genera of goodeids. In this study, the authors analysed variation in the mitochondrial cytochrome b gene to evaluate the phylogeographic relationships, genetic structure, genetic diversity and demographic history of Goodea from across its distribution range. They found low genetic differentiation and identified shared haplotypes among several regions. Geographic segregation was found in samples southwest and northeast of the Lower Lerma region, with some internal isolated groups showing phylogeographic differentiation and unique haplotypes. The AMOVA best explained genetic structure when grouped by haplogroups rather than when grouped by recognized biogeographic regions. Several regions showed null genetic diversity, raising the possibility of dispersal mediated by humans. Finally, Bayesian Skyline Plot analysis showed a population expansion for the Southwest haplogroup, except for the Armería population and sub-group II of the Northeast haplogroup. All this suggests a recent colonization of Goodea atripinnis throughout some of the biogeographic regions currently inhabited by this species. 相似文献
998.
Natalie Villar Freret-Meurer Amanda do Carmo Vaccani Gabriela dos Santos Cabiró 《Journal of fish biology》2021,99(2):695-699
Intersex has been reported regularly in wild populations of gonochoristic fish. The authors investigated the possible feminization of seahorses in a population of Hippocampus reidi in Brazil, as well as report a case of a brood pouch reduction after reproductive stimuli. The female seahorses of this population showed two kinds of morphological anomalies. The proportion of the animals affected in the study population was consistent and was uncorrelated with the sex ratio. The study indicates the changes in the sexual profile of the individual. 相似文献
999.
Rivelli Antonelli Juan F. Santander Verónica S. Nigra Ayelen D. Monesterolo Noelia E. Previtali Gabriela Primo Emilianao Otero Lisandro H. Casale César H. 《Journal of physiology and biochemistry》2021,77(4):565-576
Journal of Physiology and Biochemistry - In recent studies, we found that compounds derived from phenolic acids (CAFs) prevent the formation of the tubulin/aldose reductase complex and,... 相似文献
1000.
Woojong Lee Brock Kingstad-Bakke Brett Paulson Autumn Larsen Katherine Overmyer Chandranaik B. Marinaik Kelly Dulli Randall Toy Gabriela Vogel Katherine P. Mueller Kelsey Tweed Alex J. Walsh Jason Russell Krishanu Saha Leticia Reyes Melissa C. Skala John-Demian Sauer Dmitry M. Shayakhmetov Joshua Coon Krishnendu Roy M. Suresh 《PLoS pathogens》2021,17(1)
There is a critical need for adjuvants that can safely elicit potent and durable T cell-based immunity to intracellular pathogens. Here, we report that parenteral vaccination with a carbomer-based adjuvant, Adjuplex (ADJ), stimulated robust CD8 T-cell responses to subunit antigens and afforded effective immunity against respiratory challenge with a virus and a systemic intracellular bacterial infection. Studies to understand the metabolic and molecular basis for ADJ’s effect on antigen cross-presentation by dendritic cells (DCs) revealed several unique and distinctive mechanisms. ADJ-stimulated DCs produced IL-1β and IL-18, suggestive of inflammasome activation, but in vivo activation of CD8 T cells was unaffected in caspase 1-deficient mice. Cross-presentation induced by TLR agonists requires a critical switch to anabolic metabolism, but ADJ enhanced cross presentation without this metabolic switch in DCs. Instead, ADJ induced in DCs, an unique metabolic state, typified by dampened oxidative phosphorylation and basal levels of glycolysis. In the absence of increased glycolytic flux, ADJ modulated multiple steps in the cytosolic pathway of cross-presentation by enabling accumulation of degraded antigen, reducing endosomal acidity and promoting antigen localization to early endosomes. Further, by increasing ROS production and lipid peroxidation, ADJ promoted antigen escape from endosomes to the cytosol for degradation by proteasomes into peptides for MHC I loading by TAP-dependent pathways. Furthermore, we found that induction of lipid bodies (LBs) and alterations in LB composition mediated by ADJ were also critical for DC cross-presentation. Collectively, our model challenges the prevailing metabolic paradigm by suggesting that DCs can perform effective DC cross-presentation, independent of glycolysis to induce robust T cell-dependent protective immunity to intracellular pathogens. These findings have strong implications in the rational development of safe and effective immune adjuvants to potentiate robust T-cell based immunity. 相似文献