全文获取类型
收费全文 | 5618篇 |
免费 | 405篇 |
出版年
2023年 | 18篇 |
2022年 | 17篇 |
2021年 | 90篇 |
2020年 | 46篇 |
2019年 | 81篇 |
2018年 | 122篇 |
2017年 | 101篇 |
2016年 | 162篇 |
2015年 | 232篇 |
2014年 | 291篇 |
2013年 | 442篇 |
2012年 | 478篇 |
2011年 | 460篇 |
2010年 | 290篇 |
2009年 | 221篇 |
2008年 | 352篇 |
2007年 | 363篇 |
2006年 | 331篇 |
2005年 | 338篇 |
2004年 | 291篇 |
2003年 | 243篇 |
2002年 | 260篇 |
2001年 | 65篇 |
2000年 | 67篇 |
1999年 | 66篇 |
1998年 | 50篇 |
1997年 | 37篇 |
1996年 | 40篇 |
1995年 | 42篇 |
1994年 | 37篇 |
1993年 | 46篇 |
1992年 | 37篇 |
1991年 | 28篇 |
1990年 | 29篇 |
1989年 | 28篇 |
1988年 | 19篇 |
1987年 | 26篇 |
1986年 | 19篇 |
1985年 | 22篇 |
1984年 | 26篇 |
1983年 | 16篇 |
1982年 | 10篇 |
1981年 | 19篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有6023条查询结果,搜索用时 46 毫秒
1.
Mohammad Shamsur Rahman Maria Elena Martino Barbara Cardazzo Pierantonio Facco Paola Bordin Renzo Mioni Enrico Novelli Luca Fasolato 《Applied and environmental microbiology》2014,80(8):2372-2380
Vibrio is a very diverse genus that is responsible for different human and animal diseases. The accurate identification of Vibrio at the species level is important to assess the risks related to public health and diseases caused by aquatic organisms. The ecology of Vibrio spp., together with their genetic background, represents an important key for species discrimination and evolution. Thus, analyses of population structure and ecology association are necessary for reliable characterization of bacteria and to investigate whether bacterial species are going through adaptation processes. In this study, a population of Vibrionaceae was isolated from shellfish of the Venice lagoon and analyzed in depth to study its structure and distribution in the environment. A multilocus sequence analysis (MLSA) was developed on the basis of four housekeeping genes. Both molecular and biochemical approaches were used for species characterization, and the results were compared to assess the consistency of the two methods. In addition, strain ecology and the association between genetic information and environment were investigated through statistical models. The phylogenetic and population analyses achieved good species clustering, while biochemical identification was demonstrated to be imprecise. In addition, this study provided a fine-scale overview of the distribution of Vibrio spp. in the Venice lagoon, and the results highlighted a preferential association of the species toward specific ecological variables. These findings support the use of MLSA for taxonomic studies and demonstrate the need to consider environmental information to obtain broader and more accurate bacterial characterization. 相似文献
2.
3.
4.
Mario Stampanoni Bassi Tommaso Nuzzo Luana Gilio Mattia Miroballo Alessia Casamassa Fabio Buttari Paolo Bellantonio Roberta Fantozzi Giovanni Galifi Roberto Furlan Annamaria Finardi Arianna De Rosa Anna Di Maio Francesco Errico Diego Centonze Alessandro Usiello 《Journal of neurochemistry》2021,159(5):857-866
5.
Filippo Genovese Stefania Ferrari Giambattista Guaitoli Monica Caselli M. Paola Costi Glauco Ponterini 《Protein science : a publication of the Protein Society》2010,19(5):1023-1030
An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43′ with an excitation energy donor/acceptor pair. The dimer–monomer equilibrium of the enzyme is then characterized through steady‐state fluorescence determination of the intersubunit resonance energy transfer efficiency. 相似文献
6.
Sonia Coni Silvia Maria Serrao Zuleyha Nihan Yurtsever Laura Di Magno Rosa Bordone Camilla Bertani Valerio Licursi Zaira Ianniello Paola Infante Marta Moretti Marialaura Petroni Francesca Guerrieri Alessandro Fatica Alberto Macone Enrico De Smaele Lucia Di Marcotullio Giuseppe Giannini Marella Maroder Enzo Agostinelli Gianluca Canettieri 《Cell death & disease》2020,11(12)
7.
Based on the literature, we had predicted that the diversification within the Neotropical snake genus Bothrops occurred along a latitudinal gradient from north to south, with diversification into unoccupied niches through ecological opportunity, not correlated with geoclimatic events. Using a dated phylogeny and estimating likelihoods of ancestral states at cladogenesis events, we reconstructed ancestral areas and assessed major events of the diversification of Bothrops clades, and we also discuss systematic implications for this group. Based on the phylogeny we produced, B. lojanus was not considered as part of the genus Bothrops since the results recovered this species nested within the Bothrocophias clade. We infer that the diversification of the Miocene Bothrops pictus and Bothrops alternatus clades may be related to the uplift of the western slopes of the Andes and the Argentinian Patagonian Andes, respectively. The Pliocene Bothrops taeniatus and Bothrops osbornei clades may be related to the uplift of the eastern and northern Andes, respectively. The Plio-Pleistocene Bothrops neuwiedi clade may be related to the habitat transitions from a warmer and forested environment to a cooler and open landscape; the Bothrops jararaca (i.e. island endemic species) and Bothrops lanceolatus clades to over-water dispersal with island speciation; and Bothrops atrox clade to the appearance of the Panamanian land bridge. We found that a multitemporal and multidirectional history of diversification may be correlated with geoclimatic and dispersalist events. We argue that the vacant niche hypothesis by itself does not explain Bothrops diversification. 相似文献
8.
The role of the ceramide moiety of gangliosides, together with the deriving aggregative properties of ganglioside in solution, in the process of ganglioside-cell interactions was studied. The natural GM1(stearoyl) and the synthetic GM1(acetyl), containing the stearoyl and acetyl groups as the acyl moiety, respectively, were used in binding experiments to rat cerebellar granule cells. Regardless of the cell culture conditions, such as the presence of absence of fetal calf serum, the association of GM1(acetyl) to the cells was much greater than that of GM1(stearoyl). GM1(acetyl) was present in the incubation medium as monomers. After incubation, a large part of the total GM1(acetyl) associated to cells, 76-93% depending on the experimental conditions, was removed by washing with protein solutions. The remaining associated ganglioside was not removed by repeating washing with protein solutions or trypsin treatments and was considered as a component of the membrane. The cell association of GM1(stearoyl), present in solution as monomers as well as micelles, could be classified as serum-labile, trypsin-labile and trypsin-stable. The trypsin-stable form of association, corresponding to the molecules stably inserted into the membrane, was proportionally higher, the proportions varying with increasing incubation time and decreasing ganglioside concentration. This form of association was particularly high when incubation was performed in the presence of fetal calf serum. Incubation experiments performed with a mixture of GM1(stearoyl) and GM1(acetyl) in a molar ratio which allowed their presence in the medium as monomers as well as mixed micelles, led to a ganglioside association suggesting that besides the aggregative properties of the molecule other ganglioside properties are involved in the ganglioside-cell interaction process. 相似文献
9.
10.