全文获取类型
收费全文 | 5713篇 |
免费 | 517篇 |
出版年
2023年 | 31篇 |
2022年 | 65篇 |
2021年 | 132篇 |
2020年 | 79篇 |
2019年 | 121篇 |
2018年 | 114篇 |
2017年 | 107篇 |
2016年 | 188篇 |
2015年 | 268篇 |
2014年 | 284篇 |
2013年 | 336篇 |
2012年 | 353篇 |
2011年 | 348篇 |
2010年 | 216篇 |
2009年 | 231篇 |
2008年 | 248篇 |
2007年 | 286篇 |
2006年 | 247篇 |
2005年 | 245篇 |
2004年 | 224篇 |
2003年 | 213篇 |
2002年 | 187篇 |
2001年 | 128篇 |
2000年 | 128篇 |
1999年 | 92篇 |
1998年 | 74篇 |
1997年 | 68篇 |
1996年 | 49篇 |
1995年 | 45篇 |
1994年 | 38篇 |
1993年 | 37篇 |
1992年 | 72篇 |
1991年 | 60篇 |
1990年 | 69篇 |
1989年 | 62篇 |
1988年 | 54篇 |
1987年 | 48篇 |
1986年 | 40篇 |
1985年 | 39篇 |
1984年 | 40篇 |
1983年 | 28篇 |
1982年 | 37篇 |
1981年 | 25篇 |
1980年 | 20篇 |
1979年 | 25篇 |
1978年 | 29篇 |
1977年 | 20篇 |
1976年 | 26篇 |
1974年 | 20篇 |
1968年 | 16篇 |
排序方式: 共有6230条查询结果,搜索用时 15 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.
Tanner Miest Dyana Saenz Anne Meehan Manuel Llano Eric M. Poeschla 《Methods (San Diego, Calif.)》2009,47(4):298-303
RNAi is a powerful technology for analyzing gene function in human cells. However, its utility can be compromised by inadequate knockdown of the target mRNA or by interpretation of effects without rigorous controls. We review lentiviral vector-based methods that enable transient or stable knockdowns to trace mRNA levels in human CD4+ T cell lines and other targets. Critical controls are reviewed, including rescue of the pre-knockdown phenotype by re-expression of the targeted gene. The time from thinking about a potential knockdown target to analysis of phenotypes can be as short as a few weeks. 相似文献
4.
Paloma Rocha Arakaki Paula Andrea Borges Salgado Joo Diego de Agostini Losano Dbora Rodrigues Gonalves Rodrigo del Rio do Valle Ricardo Jos Garcia Pereira Marcilio Nichi 《American journal of primatology》2019,81(12)
Wild animal genetic resource banking (GRB) represents a valuable tool in conservation breeding programs, particularly in cases involving endangered species such as the golden‐headed lion tamarin (Leontopithecus chrysomelas). Thus, we aimed to assess a sperm freezing protocol for golden‐headed lion tamarins using two different exenders: BotuBOV® (BB) and Test Yolk Buffer® (TYB). Ejaculates were collected by penile vibrostimulation from animals housed at São Paulo Zoological Park Foundation, São Paulo, Brazil, and after immediate analysis, two aliquots were diluted in BB and TYB. Postthawing samples were evaluated for total and progressive motility, plasma membrane and acrosome integrities, mitochondrial activity, susceptibility to oxidative stress, and sperm–egg‐binding. No differences between BB and TYB were found for most seminal parameters, except for acrosome integrity and susceptibility to oxidative stress (in both cases BB showed higher values). However, in spite of these differences and regardless of the extender used, postthaw sperm motility and viability with the described protocol were encouraging (on average >50% and >80%, respectively), indicating that sperm cryopreservation may be a short‐term measure for the conservation of golden‐headed lion tamarins. 相似文献
5.
Léniz A. Portillo M. P. Fernández-Quintela Alfredo Macarulla M. T. Sarasua-Miranda A. del Hoyo M. Díez-López I. 《Journal of physiology and biochemistry》2019,75(3):311-319
Journal of Physiology and Biochemistry - Infants born small for gestational age (SGA) are at increased risk of perinatal morbidity, persistent short stature, and metabolic alterations in later... 相似文献
6.
Michael S. Lipkowitz Edgar Leal-Pinto B. Eleazar Cohen Ruth G. Abramson 《Glycoconjugate journal》2002,19(7-9):491-498
UAT, also designated galectin 9, is a multifunctional protein that can function as a urate channel/transporter, a regulator of thymocyte-epithelial cell interactions, a tumor antigen, an eosinophil chemotactic factor, and a mediator of apoptosis. We review the evidence that UAT is a transmembrane protein that transports urate, describe our molecular model for this protein, and discuss the evidence from epitope tag and lipid bilayer studies that support this model of the transporter. The properties of recombinant UAT are compared with those of urate transport into membrane vesicles derived from proximal tubule cells in rat kidney cortex. In addition, we review channel functions predicted by our molecular model that resulted in the novel finding that the urate channel activity is regulated by sugars and adenosine. Finally, the presence and possible functions of at least 4 isoforms of UAT and a closely related gene hUAT2 are discussed. Published in 2004. 相似文献
7.
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
8.
9.
10.
Andrea Schrödel 《当今生物学》2007,37(5):289-289