全文获取类型
收费全文 | 35257篇 |
免费 | 3421篇 |
国内免费 | 17篇 |
出版年
2021年 | 518篇 |
2020年 | 299篇 |
2019年 | 428篇 |
2018年 | 508篇 |
2017年 | 438篇 |
2016年 | 708篇 |
2015年 | 1121篇 |
2014年 | 1302篇 |
2013年 | 1688篇 |
2012年 | 2010篇 |
2011年 | 2118篇 |
2010年 | 1322篇 |
2009年 | 1238篇 |
2008年 | 1831篇 |
2007年 | 1885篇 |
2006年 | 1811篇 |
2005年 | 1873篇 |
2004年 | 1781篇 |
2003年 | 1785篇 |
2002年 | 1692篇 |
2001年 | 415篇 |
2000年 | 249篇 |
1999年 | 393篇 |
1998年 | 486篇 |
1997年 | 356篇 |
1996年 | 358篇 |
1995年 | 287篇 |
1994年 | 332篇 |
1993年 | 312篇 |
1992年 | 292篇 |
1991年 | 266篇 |
1990年 | 266篇 |
1989年 | 238篇 |
1988年 | 264篇 |
1987年 | 247篇 |
1986年 | 227篇 |
1985年 | 307篇 |
1984年 | 398篇 |
1983年 | 319篇 |
1982年 | 377篇 |
1981年 | 440篇 |
1980年 | 416篇 |
1979年 | 258篇 |
1978年 | 258篇 |
1977年 | 277篇 |
1976年 | 265篇 |
1975年 | 188篇 |
1974年 | 243篇 |
1973年 | 196篇 |
1970年 | 144篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In vivo EMG biofeedback was found to be an effective pedagogical tool for removing unwanted left-hand tension in nine violin and viola players. Improvement occurred rapidly and persisted throughout a 5-month follow-up period. Further studies will be necessary to assess the effect of biofeedback independent of placebo effects. The brevity of the method and the magnitude of improvement warrant further investigation. 相似文献
2.
The ability to metabolically label proteins with 35S-methionine is critical for the analysis of protein synthesis and turnover. Despite the importance of this approach, however, efficient labeling of proteins in vivo is often limited by a low number of available methionine residues, or by deleterious side-effects associated with protein overexpression. To overcome these limitations, we have created a methionine-rich variant of the widely used HA tag, called HAM, for use with ectopically expressed proteins. Here we describe the development of a series of vectors, and corresponding antisera, for the expression and detection of HAM-tagged proteins in mammalian cells. We show that the HAM tag dramatically improves the sensitivity of 35S-methionine labeling, and permits the analysis of Myc oncoprotein turnover even when HAM-tagged Myc is expressed at levels comparable to that of the endogenous protein. Because of the improved sensitivity provided by the HAM tag, the vectors and antisera described here should be useful for the analysis of protein synthesis and destruction at physiological levels of protein expression. 相似文献
3.
4.
HIF-1 expression in healing wounds: HIF-1alpha induction in primary inflammatory cells by TNF-alpha 总被引:12,自引:0,他引:12
5.
6.
7.
Ting‐Hang Liu Chia‐Lin Chyan Feng‐Yin Li Ying‐Jie Chen Jason T. C. Tzen 《Biotechnology progress》2011,27(6):1760-1767
It has been demonstrated that caleosin alone is sufficient to stabilize artificial oil bodies. A series of recombinant caleosins, mutated with 3, 5, 8, 11, 13, 15, and 17 extra Lys residues and over‐expressed in Escherichia coli, were used as carrier proteins to render biotin as a hapten on the surface of artificial oil bodies for antibody production. Biotinylation levels of the recombinant caleosins were step‐wisely elevated as the number of extra Lys residues increased, and the biotinylated Lys residues were identified by mass spectrometric analysis. Polyclonal antibodies against biotin were successfully generated in rats injected with artificial oil bodies constituted with each of the biotinylated caleosins. Moreover, those generated via the biotinylated caleosins with eight or more extra Lys residues no longer recognized caleosin. It appears that engineered Lys‐rich caleosins are suitable carrier proteins for the production of antibodies against small molecules. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011 相似文献
8.
Tuberculate mycorrhizae on Pinus contorta (lodgepole pine) have previously been shown to reduce acetylene, but an outstanding question has been to what degree these structures could meet the nitrogen requirements of the tree. We compared the growth, tissue nitrogen contents, and stable nitrogen isotope ratios of P. contorta growing in gravel pits to the same species growing on adjacent intact soil. Trees growing in severely nitrogen deficient gravel pits had virtually identical growth rates and tissue nitrogen contents to those growing on intact soil that had nitrogen levels typical for the area. δ15N values for trees in the gravel pits were substantially lower than δ15N values for trees on intact soil, and isotope ratios in vegetation were lower than the isotope ratios of the soil. The form of soil nitrogen in the gravel pits was almost exclusively nitrate, while ammonium predominated in the intact soil. Discrimination against 15N during plant uptake of soil nitrate in the highly N-deficient soil should be weak or nonexistent. Therefore, the low δ15N in the gravel pit trees suggests that trees growing in gravel pits were using another nitrogen source in addition to the soil. Precipitation-borne nitrogen in the study area is extremely low. In conjunction with our other work, these findings strongly suggests that P. contorta and its microbial symbionts or associates fix nitrogen in sufficient amounts to sustain vigorous tree growth on the most nitrogen-deficient soils. 相似文献
9.
10.