全文获取类型
收费全文 | 10617篇 |
免费 | 904篇 |
出版年
2023年 | 33篇 |
2022年 | 77篇 |
2021年 | 157篇 |
2020年 | 118篇 |
2019年 | 157篇 |
2018年 | 199篇 |
2017年 | 172篇 |
2016年 | 269篇 |
2015年 | 435篇 |
2014年 | 441篇 |
2013年 | 635篇 |
2012年 | 727篇 |
2011年 | 679篇 |
2010年 | 469篇 |
2009年 | 431篇 |
2008年 | 579篇 |
2007年 | 633篇 |
2006年 | 553篇 |
2005年 | 557篇 |
2004年 | 562篇 |
2003年 | 553篇 |
2002年 | 630篇 |
2001年 | 130篇 |
2000年 | 91篇 |
1999年 | 139篇 |
1998年 | 155篇 |
1997年 | 145篇 |
1996年 | 128篇 |
1995年 | 109篇 |
1994年 | 101篇 |
1993年 | 101篇 |
1992年 | 106篇 |
1991年 | 80篇 |
1990年 | 71篇 |
1989年 | 64篇 |
1988年 | 52篇 |
1987年 | 49篇 |
1986年 | 40篇 |
1985年 | 53篇 |
1984年 | 67篇 |
1983年 | 61篇 |
1982年 | 95篇 |
1981年 | 84篇 |
1980年 | 63篇 |
1979年 | 55篇 |
1978年 | 52篇 |
1977年 | 51篇 |
1976年 | 51篇 |
1975年 | 35篇 |
1973年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.
Parot P Dufrêne YF Hinterdorfer P Le Grimellec C Navajas D Pellequer JL Scheuring S 《Journal of molecular recognition : JMR》2007,20(6):418-431
To introduce this special issue of the Journal of Molecular Recognition dedicated to the applications of atomic force microscopy (AFM) in life sciences, this paper presents a short summary of the history of AFM in biology. Based on contributions from the first international conference of AFM in biological sciences and medicine (AFM BioMed Barcelona, 19-21 April 2007), we present and discuss recent progress made using AFM for studying cells and cellular interactions, probing single molecules, imaging biosurfaces at high resolution and investigating model membranes and their interactions. Future prospects in these different fields are also highlighted. 相似文献
982.
Teulon JM Odorico M Chen SW Parot P Pellequer JL 《Journal of molecular recognition : JMR》2007,20(6):508-515
The energy landscape of the uranyl (UO2) chelate dissociated from a monoclonal antibody U08S was investigated using dynamic force spectroscopy (DFS). The uranyl ion (UO2(2+)) is chelated with the ligand dicarboxy-phenanthroline (DCP). The monoclonal antibody U08S was raised against UO2-DCP and does not cross-react with DCP alone. The results of plotting the most probable force against the logarithm of the loading rate show two distinguished values of slopes of multiple fitting lines, as observed in our previous study on that system with monoclonal antibody U04S (Odorico et al., 2007a. Biophys. J. 93: 645-654.). It indicates an unbinding process undergoing at least two activation states. We have generated the histogram of unbinding events with respect to the composite stiffness of the complex between the protein and the uranyl compound. Combining the model of Bell and Evans with that of Williams, we have estimated the number of parallel bonds involved in the unbinding process and determined the value of stiffness for individual bonds. We propose that the uranyl compound binds to the two antibodies U04S and U0c at structurally equivalent locations and forms the interaction with similar coordination modes. In addition, the unbinding process goes through two steps; the first weakens the bonding of the central metal with AspL50 of the antibody and the second breaks other non-bonded interactions of the compound with the antibody. 相似文献
983.
Levasseur A Orlando L Bailly X Milinkovitch MC Danchin EG Pontarotti P 《Biological reviews of the Cambridge Philosophical Society》2007,82(4):551-572
To demonstrate that a given change in the environment has contributed to the emergence of a given genotypic and phenotypic shift during the course of evolution, one should ask to what extent such shifts would have occurred without environmental change. Of course, such tests are rarely practical but phenotypic novelties can still be correlated to genomic shifts in response to environmental changes if enough information is available. We surveyed and re-evaluated the published data in order to estimate the role of environmental changes on the course of species and genomic evolution. Only a few published examples clearly demonstrate a causal link between a given environmental change and the fixation of a genomic variant resulting in functional modification (gain, loss or alteration of function). Many others suggested a link between a given phenotypic shift and a given environmental change but failed to identify the underlying genomic determinant(s) and/or the associated functional consequence(s). The proportion of genotypic and phenotypic variation that is fixed concomitantly with environmental changes is often considered adaptive and hence, the result of positive selection, even though alternative causes, such as genetic drift, are rarely investigated. Therefore, the second aim herein is to review evidence for the mechanisms leading to fixation. 相似文献
984.
985.
986.
Rehab Kamel Simone Garcia Frank Lezoualc'h Rodolphe Fischmeister Sylviane Muller Johan Hoebeke Pierre Eftekhari 《BMC developmental biology》2007,7(1):34
Background
The presence of functional 5-HT4 receptors in human and its involvement in neonatal lupus erythematosus (NLE) have prompted us to study the receptor expression and role during embryogenesis. Earlier we managed to demonstrate that female BALB/c mice immunized against the second extracellular loop (SEL) of the 5-HT4 receptor gave birth to pups with heart block. To explain this phenomenon we investigated the expression of 5-HT4 receptors during mouse embryogenesis. At the same time we looked whether the consequence of 5-HT4 receptor immunomodulation observed earlier is in relation to receptor expression. 相似文献987.
Farrokh Modabber Pierre A Buffet Els Torreele Geneviéve Milon Simon L Croft 《Kinetoplastid biology and disease》2007,6(1):3
Background
A meeting was organized by Drugs for Neglected Diseases initiative (DNDi) and the Institute Pasteur (IP), Paris, to review the treatment for all forms of cutaneous leishmaniasis (CL) and to propose a strategy for the development of new efficacious and affordable treatments. 相似文献988.
Barthélémy RM Grino M Pontarotti P Casanova JP Faure E 《Cellular & molecular biology letters》2007,12(4):573-583
Chaetognaths constitute a small marine phylum of approximately 120 species. Two classes of both 18S and 28S rRNA gene sequences have been evidenced in this phylum, even though significant intraindividual variation in the sequences of rRNA genes is unusual in animal genomes. These observations led to the hypothesis that this unusual genetic characteristic could play one or more physiological role(s). Using in situ hybridization on the frontal sections of the chaetognath Spadella cephaloptera, we found that the 18S Class I genes are expressed in the whole body, with a strong expression throughout the gut epithelium, whereas the expression of the 18S Class II genes is restricted to the oocytes. Our results could suggest that the paralog products of the 18S Class I genes are probably the "housekeeping" 18S rRNAs, whereas those of class II would only be essential in specific tissues. These results provide support for the idea that each type of 18S paralog is important for specific cellular functions and is under the control of selective factors. 相似文献
989.
Alazard D Badillo C Fardeau ML Cayol JL Thomas P Roldan T Tholozan JL Ollivier B 《Extremophiles : life under extreme conditions》2007,11(1):33-39
A new alkaliphilic and moderately halophilic, strictly anaerobic, fermentative bacterium (strain IMP-300T) was isolated from a groundwater sample in the zone of the former soda lake Texcoco in Mexico. Strain IMP-300T was Gram-positive, non-sporulated, motile and rod-shaped. It grew within a pH range from 7.5 to 10.5, and an optimum at 9.5.
The organism was obligately dependent on the presence of sodium salts. Growth showed an optimum at 35°C with absence of growth
above 45°C. It fermented peptone and a few amino acids, preferentially arginine and ornithine, with production of acetate,
propionate, and ammonium. Its fatty acid pattern was mainly composed of straight chain saturated, unsaturated, and cyclopropane
fatty acids. The G + C content of genomic DNA was 40.0 mol%. Analysis of the 16S rRNA gene sequence indicated that the new
isolate belongs to the genus Tindallia, in the low G + C Gram-positive phylum. Phylogenetically, strain IMP-300T has Tindallia californiensis, as closest relative with a 97.5% similarity level between their 16S rDNA gene sequences, but the DNA–DNA re-association
value between the two DNAs was only 42.2%. On the basis of differences in genotypic, phenotypic, and phylogenetic characteristics,
strain IMP-300T is proposed as a new species of the genus Tindallia, T. texcoconensis sp. nov. (type strain IMP-300T = DSM 18041T = JCM 13990T). 相似文献
990.
Spatial Analysis of Production by Macrophytes,Phytoplankton and Epiphyton in a Large River System under Different Water-Level Conditions 总被引:1,自引:0,他引:1
Relative contributions by macrophytes, epiphyton and phytoplankton to total primary production was estimated in a large (∼300 km2) widening of the St. Lawrence River (Canada), over a 2-year period with contrasting flows and water levels. Spatially-explicit
estimates of whole-system production were obtained by combining field measurements with remotely sensed data and empirical
models using GIS. Primary production and relative contributions of each producer type differed markedly between open-water
and wetland habitats. Spatial differences within each habitat arose from interactions between physical factors including light,
water depth, water transit times and wind stress. At the whole-system level, annual primary production represented 105 gC m−2 y−1, divided roughly equally among phytoplankton (34%), submerged macrophytes (27%), emergent macrophytes (23%) and epiphyton
(16%). A 10% decrease in annual flows and 1-m decline in water levels between 2000 and 2001 resulted in a 50% loss of marsh
habitat, a 60% increase in phytoplankton production in the open-water zone, and in the appearance of conspicuous filamentous
algal mats. Low water levels induced substantial shifts in the spatial configuration and relative importance of primary producers
although total river primary production remained stable between years. 相似文献