全文获取类型
收费全文 | 1039篇 |
免费 | 69篇 |
专业分类
1108篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 14篇 |
2020年 | 6篇 |
2019年 | 16篇 |
2018年 | 12篇 |
2017年 | 19篇 |
2016年 | 27篇 |
2015年 | 60篇 |
2014年 | 54篇 |
2013年 | 74篇 |
2012年 | 109篇 |
2011年 | 87篇 |
2010年 | 60篇 |
2009年 | 42篇 |
2008年 | 72篇 |
2007年 | 69篇 |
2006年 | 49篇 |
2005年 | 48篇 |
2004年 | 55篇 |
2003年 | 38篇 |
2002年 | 35篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 5篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 12篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有1108条查询结果,搜索用时 0 毫秒
91.
The phylogeny of polar fishes and the structure,function and molecular evolution of hemoglobin 总被引:1,自引:0,他引:1
Fishes thriving in polar habitats offer many opportunities for comparative approaches to understanding protein thermal adaptations.
Investigations on the remarkable evolutionary adaptations to these environments of basic proteins such as hemoglobin, the
oxygen carrier, can provide new insights into the mechanisms studied in temperate organisms and can shed light on convergent
processes evolved in response to thermal adaptations. At the molecular level, hemoglobins are one of the most intriguing systems
for studying the relationships between environmental conditions and adaptations. This review summarizes the current knowledge
on molecular structure, biological function and phylogeny of hemoglobins of fish species living in both polar habitats but
having different evolutionary histories. In benthic, non-migratory, cold-adapted fishes, the stability of thermal conditions
may have generated no or few variations in selective pressures on globin sequences through evolutionary time, so that sequences
retain the species phylogenetic “signal”. In pelagic, migratory, cold-adapted or temperate fishes, variations in selective
pressures on globin sequences caused by variations in temperature accompanying the dynamic life style may have disrupted the
phylogenetic “signal” in phenetic trees. 相似文献
92.
93.
94.
95.
Rafael L. Rodríguez Jennifer Danzy Cramer Christopher A. Schmitt Tegan J. Gaetano J. Paul Grobler Nelson B. Freimer Trudy R. Turner 《Biological journal of the Linnean Society. Linnean Society of London》2015,114(3):527-537
Sexual traits vary tremendously in static allometry. This variation may be explained in part by body size‐related differences in the strength of selection. We tested this hypothesis in two populations of vervet monkeys, using estimates of the level of condition dependence for different morphological traits as a proxy for body size‐related variation in the strength of selection. In support of the hypothesis, we found that the steepness of allometric slopes increased with the level of condition dependence. One trait of particular interest, the penis, had shallow allometric slopes and low levels of condition dependence, in agreement with one of the most consistent patterns yet detected in the study of allometry, namely that of genitalia exhibiting shallow allometries. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 527–537. 相似文献
96.
The peculiar heme pocket of the 2/2 hemoglobin of cold-adapted Pseudoalteromonas haloplanktis TAC125
Barry D. Howes Daniela Giordano Leonardo Boechi Roberta Russo Simona Mucciacciaro Chiara Ciaccio Federica Sinibaldi Maria Fittipaldi Marcelo A. Mart�� Dar��o A. Estrin Guido di Prisco Massimo Coletta Cinzia Verde Giulietta Smulevich 《Journal of biological inorganic chemistry》2011,16(2):299-311
The genome of the cold-adapted bacterium Pseudoalteromonas haloplanktis TAC125 contains multiple genes encoding three distinct monomeric hemoglobins exhibiting a 2/2 ??-helical fold. In the present work, one of these hemoglobins is studied by resonance Raman, electronic absorption and electronic paramagnetic resonance spectroscopies, kinetic measurements, and different bioinformatic approaches. It is the first cold-adapted bacterial hemoglobin to be characterized. The results indicate that this protein belongs to the 2/2 hemoglobin family, Group II, characterized by the presence of a tryptophanyl residue on the bottom of the heme distal pocket in position G8 and two tyrosyl residues (TyrCD1 and TyrB10). However, unlike other bacterial hemoglobins, the ferric state, in addition to the aquo hexacoordinated high-spin form, shows multiple hexacoordinated low-spin forms, where either TyrCD1 or TyrB10 can likely coordinate the iron. This is the first example in which both TyrCD1 and TyrB10 are proposed to be the residues that are alternatively involved in heme hexacoordination by endogenous ligands. 相似文献
97.
98.
Lactoferrin (LF) is an iron-binding glycoprotein of the transferrin family, today known to have multifunctional physiological
activities. In humans, under normal conditions, LF has been found in blood, mucosal secretions, gastrointestinal fluids, urine
and mostly in milk and colostrum. The first pioneering immunohistochemical report about LF distribution in human tissues dated
in 1978; successively, many studies have been performed to analyze the LF immunohistochemical pattern in different normal
and neoplastic tissues. In this review, we present data from literature concerning the evidence of LF in tumors together with
those by us obtained during more than 25 years; the immunohistochemical applications to human neoplastic tissues have been
done to investigate the LF pathogenetic role as well as its activity in cancer. After a systematic analysis of LF immunoreactivity
in different human districts, a possible explanation for its presence and function has been modulated for each site or tissue,
according to experimental evidences obtained either by in vivo as well as by in vitro studies. 相似文献
99.
Synthesis and evaluation of quinoxaline derivatives as potential influenza NS1A protein inhibitors 总被引:1,自引:0,他引:1
You L Cho EJ Leavitt J Ma LC Montelione GT Anslyn EV Krug RM Ellington A Robertus JD 《Bioorganic & medicinal chemistry letters》2011,21(10):3007-3011
A library of quinoxaline derivatives were prepared to target non-structural protein 1 of influenza A (NS1A) as a means to develop anti-influenza drug leads. An in vitro fluorescence polarization assay demonstrated that these compounds disrupted the dsRNA-NS1A interaction to varying extents. Changes of substituent at positions 2, 3 and 6 on the quinoxaline ring led to variance in responses. The most active compounds (35 and 44) had IC50 values in the range of low micromolar concentration without exhibiting significant dsRNA intercalation. Compound 44 was able to inhibit influenza A/Udorn/72 virus growth. 相似文献
100.
Molecular replacement (MR) is widely used for addressing the phase problem in X-ray crystallography. Historically, crystallographers have had limited success using NMR structures as MR search models. Here, we report a comprehensive investigation of the utility of protein NMR ensembles as MR search models, using data for 25 pairs of X-ray and NMR structures solved and refined using modern NMR methods. Starting from NMR ensembles prepared by an improved protocol, FindCore, correct MR solutions were obtained for 22 targets. Based on these solutions, automatic model rebuilding could be done successfully. Rosetta refinement of NMR structures provided MR solutions for another two proteins. We also demonstrate that such properly prepared NMR ensembles and X-ray crystal structures have similar performance when used as MR search models for homologous structures, particularly for targets with sequence identity >40%. 相似文献