全文获取类型
收费全文 | 10265篇 |
免费 | 1353篇 |
国内免费 | 3772篇 |
专业分类
15390篇 |
出版年
2024年 | 108篇 |
2023年 | 283篇 |
2022年 | 409篇 |
2021年 | 472篇 |
2020年 | 454篇 |
2019年 | 536篇 |
2018年 | 362篇 |
2017年 | 361篇 |
2016年 | 447篇 |
2015年 | 598篇 |
2014年 | 815篇 |
2013年 | 762篇 |
2012年 | 970篇 |
2011年 | 863篇 |
2010年 | 726篇 |
2009年 | 742篇 |
2008年 | 778篇 |
2007年 | 765篇 |
2006年 | 697篇 |
2005年 | 628篇 |
2004年 | 501篇 |
2003年 | 438篇 |
2002年 | 358篇 |
2001年 | 341篇 |
2000年 | 356篇 |
1999年 | 232篇 |
1998年 | 147篇 |
1997年 | 130篇 |
1996年 | 73篇 |
1995年 | 73篇 |
1994年 | 55篇 |
1993年 | 60篇 |
1992年 | 85篇 |
1991年 | 72篇 |
1990年 | 81篇 |
1989年 | 78篇 |
1988年 | 62篇 |
1987年 | 54篇 |
1986年 | 50篇 |
1985年 | 41篇 |
1984年 | 39篇 |
1983年 | 30篇 |
1982年 | 44篇 |
1981年 | 23篇 |
1980年 | 14篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
M del Mar Medina-Puerta A Garrido-Pertierra 《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,83(1):215-220
The enzyme 6-phosphogluconate dehydrogenase (6-phospho-D-gluconate: NADP+ oxidoreductase, decarboxylating EC 1.1.1.44) from bass liver has been purified to over 95% of homogeneity by gel filtration, affinity and ion exchange chromatographies. The apparent molecular weight was estimated by gel filtration chromatography to about 100,000. Analysis of the enzyme on sodium dodecyl sulphate polyacrylamide gel electrophoresis showed to be a dimeric protein. The effect of pH and kinetic properties were studied. 相似文献
3.
4.
5.
A Soler C García del Río L García-Torres F Vargas A Martín-Andrés C Osorio 《Revista Espanola de Fisiología》1985,41(1):107-116
The effects of changes in arterial pressure and in circulating volume on Plasma Renin Activity (PRA) in the intact rat were compared by two experimental procedures. Gradual volume depletion was induced by intraperitoneal injection of a hyperoncotic polyethyleneglycol solution (PEG) in absence of acute changes in Systolic Arterial Pressure (SAP). SAP was measured in the conscious state by the tail cuff technique. Plasma Protein Concentration (PPC) and Hematocrit (Hct) increases after PEG injection were compared as the index for measuring the Plasma Volume Reduction (PVR). PRA showed a significant (p less than 0.001) linear relationship with PPC, suggesting a direct dependence of renin secretion on volume depletion. Acute changes in the circulating volume were induced by controlled hemorrhages of 5.0, 10.0, 15.0 and 20.0 ml of blood/kg body weight. The increase in PRA showed a significant relationship with the changes in circulating volume, but it did not show any dependence on the changes in Mean Arterial Pressure (MAP). Our results suggest that, in the intact and conscious rat, renin secretion responds to the information from the cardiopulmonary volume receptors rather than to that from the high pressure receptors. 相似文献
6.
7.
8.
Andrea Schrödel 《当今生物学》2007,37(5):289-289
9.
As chemical reactions related to the regulation of cell proliferation are governed by availability, amount, and concentration of relevant molecules, it has been suggested that cell size is an important factor in the control of cell cycle. We have measured the size of proliferating cells of Allium cepa roots in which growth rate was modified by changes in growth temperature. Two independent cell size parameters have been measured by cytophotometry: cell surface area projection and cell protein content. Average cell sizes of both the proliferating cell population and the subpopulation at the end of mitosis show that cell size increases with growth rate. Calculation of cell size at initiation of DNA replication clearly indicates that average cell size at this point is not growth invariant but positively correlated with growth rate. 相似文献
10.
Immunological identification of yeast SCO1 protein as a component of the inner mitochondrial membrane 总被引:4,自引:0,他引:4
Summary The SCO1 gene of Saccharomyces cerevisiae encodes a 30 kDa protein which is specifically required for a post-translational step in the accumulation of subunits 1 and 2 of cytochrome c oxidase (COXI and COXII). Antibodies directed against a -Gal::SCO1 fusion protein detect SCO1 in the mitochondrial fraction of yeast cells. The SCO1 protein is an integral membrane protein as shown by its resistance to alkaline extraction and by its solubilization properties upon treatment with detergents. Based on the results obtained by isopycnic sucrose gradient centrifugation and by digitonin treatment of mitochondria, SCO1 is a component of the inner mitochondrial membrane. Membrane localization is mediated by a stretch of 17 hydrophobic amino acids in the amino-terminal region of the protein. A truncated SCO1 derivative lacking this segment, is no longer bound to the membrane and simultaneously loses its biological function. The observation that membrane localization of SCO1 is affected in mitochondria of a rho
0 strain, hints at the possible involvement of mitochondrially coded components in ensuring proper membrane insertion. 相似文献