全文获取类型
收费全文 | 734篇 |
免费 | 62篇 |
出版年
2023年 | 4篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 13篇 |
2016年 | 19篇 |
2015年 | 44篇 |
2014年 | 28篇 |
2013年 | 48篇 |
2012年 | 41篇 |
2011年 | 43篇 |
2010年 | 25篇 |
2009年 | 21篇 |
2008年 | 32篇 |
2007年 | 39篇 |
2006年 | 38篇 |
2005年 | 40篇 |
2004年 | 54篇 |
2003年 | 40篇 |
2002年 | 46篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1972年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1962年 | 3篇 |
1960年 | 3篇 |
1956年 | 2篇 |
排序方式: 共有796条查询结果,搜索用时 46 毫秒
791.
792.
Paula Vickerton Jonathan C. Jarvis James A. Gallagher Riaz Akhtar Hazel Sutherland Nathan Jeffery 《Proceedings. Biological sciences / The Royal Society》2014,281(1788)
Muscular contraction plays a pivotal role in the mechanical environment of bone, but controlled muscular contractions are rarely used to study the response of bone to mechanical stimuli. Here, we use implantable stimulators to elicit programmed contractions of the rat tibialis anterior (TA) muscle. Miniature stimulators were implanted in Wistar rats (n = 9) to induce contraction of the left TA every 30 s for 28 days. The right limb was used as a contralateral control. Hindlimbs were imaged using microCT. Image data were used for bone measurements, and to construct a finite-element (FE) model simulation of TA forces propagating through the bone. This simulation was used to target subsequent bone histology and measurement of micromechanical properties to areas of high strain. FE mapping of simulated strains revealed peak values in the anterodistal region of the tibia (640 µε ± 30.4 µε). This region showed significant increases in cross-sectional area (28.61%, p < 0.05) and bone volume (30.29%, p < 0.05) in the stimulated limb. Histology revealed a large region of new bone, containing clusters of chondrocytes, indicative of endochondral ossification. The new bone region had a lower elastic modulus (8.8 ± 2.2 GPa) when compared with established bone (20 ± 1.4 GPa). Our study provides compelling new evidence of the interplay between muscle and bone. 相似文献
793.
Andrew W. Munro Hazel M. GirvanKirsty J. McLean 《Biochimica et Biophysica Acta (BBA)/General Subjects》2007
The cytochromes P450 (P450s) are a broad class of heme b-containing mono-oxygenase enzymes. The vast majority of P450s catalyse reductive scission of molecular oxygen using electrons usually derived from coenzymes (NADH and NADPH) and delivered from redox partner proteins. Evolutionary advantages may be gained by fusion of one or more redox partners to the P450 enzyme in terms of e.g. catalytic efficiency. This route was taken by the well characterized flavocytochrome P450BM3 system (CYP102A1) from Bacillus megaterium, in which soluble P450 and cytochrome P450 reductase enzymes are covalently linked to produce a highly efficient electron transport system for oxygenation of fatty acids and related molecules. However, genome analysis and ongoing enzyme characterization has revealed that there are a number of other novel classes of P450–redox partner fusion enzymes distributed widely in prokaryotes and eukaryotes. This review examines our current state of knowledge of the diversity of these fusion proteins and explores their structural composition and evolutionary origins. 相似文献
794.
Summary The N-terminal 125 amino acids of theDrosophila P element transposase are necessary and sufficient for the nuclear localisation of a hybridlacZ gene product in most cell types of theDrosophila embryo. A P-lacZ enhancer-trap element lacking these residues is of use in visualizing the shapes of P-lacZ-expressing cells. 相似文献
795.
W N Hazel R Smock M D Johnson 《Proceedings. Biological sciences / The Royal Society》1990,242(1305):181-187
We develop a genetic model for conditional strategies which places such strategies in the context of phenotypic plasticity. The model, which treats conditional strategies as polygenic threshold traits, indicates that, given requisite genetic variation in reaction norms, conditional strategies will evolve to their optimum level and be maintained by stabilizing selection, provided environmental variation results in a fitness trade-off for the alternative conditional phenotypes. The precise value for the evolutionary optimum is found to depend primarily on the probability density function of the environmental variation that influences the production of the conditional phenotypes and the magnitude of the fitness trade-offs of the conditional phenotypes across such environmental variation. The model is tested by application to three well-studied conditional strategies. In each case the predictions of the model are in good agreement with the results of these studies. 相似文献
796.
Fiona E Pryde Hazel C Gorham Edward J Louis 《Current opinion in genetics & development》1997,7(6):822-828
The recent characterisation of subtelomeric regions from a variety of organisms from yeast to man has led to the realisation that all chromosome ends are similar in structure although maintenance of the terminus varies. The mosaic of repeats and proteins associated with telomeres has an architectural role which divides the genome into two domains, allowing for the adaptive use of the region as well as the evolution of non-telomerase-mediated telomere maintenance. 相似文献