全文获取类型
收费全文 | 78335篇 |
免费 | 5386篇 |
国内免费 | 17篇 |
出版年
2023年 | 424篇 |
2022年 | 635篇 |
2021年 | 1412篇 |
2020年 | 1067篇 |
2019年 | 1350篇 |
2018年 | 2032篇 |
2017年 | 1760篇 |
2016年 | 2524篇 |
2015年 | 3480篇 |
2014年 | 3690篇 |
2013年 | 4766篇 |
2012年 | 5538篇 |
2011年 | 5221篇 |
2010年 | 3426篇 |
2009年 | 3011篇 |
2008年 | 4042篇 |
2007年 | 3974篇 |
2006年 | 3779篇 |
2005年 | 3255篇 |
2004年 | 3210篇 |
2003年 | 2811篇 |
2002年 | 2673篇 |
2001年 | 1855篇 |
2000年 | 1715篇 |
1999年 | 1441篇 |
1998年 | 833篇 |
1997年 | 625篇 |
1996年 | 564篇 |
1995年 | 562篇 |
1994年 | 468篇 |
1993年 | 436篇 |
1992年 | 821篇 |
1991年 | 773篇 |
1990年 | 702篇 |
1989年 | 686篇 |
1988年 | 612篇 |
1987年 | 614篇 |
1986年 | 544篇 |
1985年 | 528篇 |
1984年 | 451篇 |
1983年 | 401篇 |
1982年 | 328篇 |
1981年 | 264篇 |
1979年 | 409篇 |
1978年 | 281篇 |
1975年 | 270篇 |
1974年 | 318篇 |
1973年 | 319篇 |
1972年 | 277篇 |
1970年 | 258篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
122.
123.
R. Brändén T. Nilsson S. Styring 《Biochemical and biophysical research communications》1980,92(4):1297-1305
A sensitive and reliable method to determine the stereochemical composition of 3-phosphoglyceric acid is presented. Results obtained with this method show that 3-phosphoglyceric acid formed in the ribulose-1,5-bisphosphate carboxylase reaction is a mixture of 10% L-3-PGA and 90% D-3-PGA. 相似文献
124.
125.
126.
M. Konečná 《Zeitschrift fur angewandte Ichthyologie》2012,28(5):806-810
This study focuses on assessing the reproduction mode of an important model species for evolutionary and behavioural ecology by using digital image analysis: the European bitterling Rhodeus amarus (Bloch, 1782). Specifications of mode of reproduction were determined using oocyte size distribution, seasonal dynamics in mean oocyte diameter and total number of oocytes in ovary samples gained from April to July 2007. The rapid oocyte count was enabled by using lucia image analysis software, which also provided measurement and colour estimations of oocytes. Bitterling ovaries showed features typical for indeterminate spawners, i.e. a continuous distribution of oocyte size over the reproductive season and recruitment of new pre‐vitelogenic oocytes in the second half of the reproductive season. These results are consistent with the view that the European bitterling is a batch spawning fish with indeterminate fecundity. 相似文献
127.
The peptidic sequence (Sarcosine-1-Isoleucine-8)-Angiotensin II has been demonstrated to be an in vitro specific and competitive antagonist of the Angiotensin II action. The present results show it to be a competitive antagonist also in vivo since pA2 values are similar, always reaches a 100% response on increasing the Angiotensin II dose, and when relating log (DR-1) and log dose of agonist, the slope is very near to one (0.925). 相似文献
128.
129.
The effects produced on bacteriorhodopsin by low concentrations of several detergents have been studied by absorption and fourth-derivative spectrophotometry. Sodium dodecyl sulfate induces the appearance of the blue form of bacteriorhodopsin (λmax = 600 nm) at pH values up to 7.0 in a reversible manner. The apparent pK of the purple-to-blue transition raised with increasing concentration of SDS. Of the other detergents tested, only sodium dodecyl-N-sarcosinate showed a slight red-shift of the absorption band to 580 nm, whereas sodium taurocholate, Triton X-100 and cetyltrimethylammonium bromide did not favour the appearance of the blue form. The effect of SDS was found to be consistent with a localized conformational change that moves away the counter-ion of the protonated Schiff base. 相似文献
130.
Laia Castells-Roca Jordi Pijuan Francisco Ferrezuelo Gemma Bellí Enrique Herrero 《PloS one》2016,11(1)
Cth2 is an mRNA-binding protein that participates in remodeling yeast cell metabolism in iron starvation conditions by promoting decay of the targeted molecules, in order to avoid excess iron consumption. This study shows that in the absence of Cth2 immediate upregulation of expression of several of the iron regulon genes (involved in high affinity iron uptake and intracellular iron redistribution) upon oxidative stress by hydroperoxide is more intense than in wild type conditions where Cth2 is present. The oxidative stress provokes a temporary increase in the levels of Cth2 (itself a member of the iron regulon). In such conditions Cth2 molecules accumulate at P bodies-like structures when the constitutive mRNA decay machinery is compromised. In addition, a null Δcth2 mutant shows defects, in comparison to CTH2 wild type cells, in exit from α factor-induced arrest at the G1 stage of the cell cycle when hydroperoxide treatment is applied. The cell cycle defects are rescued in conditions that compromise uptake of external iron into the cytosol. The observations support a role of Cth2 in modulating expression of diverse iron regulon genes, excluding those specifically involved in the reductive branch of the high-affinity transport. This would result in immediate adaptation of the yeast cells to an oxidative stress, by controlling uptake of oxidant-promoting iron cations. 相似文献