全文获取类型
收费全文 | 36925篇 |
免费 | 3598篇 |
国内免费 | 18篇 |
专业分类
40541篇 |
出版年
2022年 | 236篇 |
2021年 | 549篇 |
2020年 | 324篇 |
2019年 | 426篇 |
2018年 | 511篇 |
2017年 | 455篇 |
2016年 | 761篇 |
2015年 | 1191篇 |
2014年 | 1370篇 |
2013年 | 1768篇 |
2012年 | 2077篇 |
2011年 | 2167篇 |
2010年 | 1352篇 |
2009年 | 1291篇 |
2008年 | 1895篇 |
2007年 | 1994篇 |
2006年 | 1882篇 |
2005年 | 1933篇 |
2004年 | 1827篇 |
2003年 | 1826篇 |
2002年 | 1765篇 |
2001年 | 481篇 |
2000年 | 298篇 |
1999年 | 444篇 |
1998年 | 509篇 |
1997年 | 378篇 |
1996年 | 374篇 |
1995年 | 303篇 |
1994年 | 354篇 |
1993年 | 319篇 |
1992年 | 342篇 |
1991年 | 299篇 |
1990年 | 296篇 |
1989年 | 275篇 |
1988年 | 274篇 |
1987年 | 268篇 |
1986年 | 247篇 |
1985年 | 327篇 |
1984年 | 426篇 |
1983年 | 335篇 |
1982年 | 396篇 |
1981年 | 452篇 |
1980年 | 423篇 |
1979年 | 264篇 |
1978年 | 276篇 |
1977年 | 289篇 |
1976年 | 271篇 |
1975年 | 192篇 |
1974年 | 239篇 |
1973年 | 206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.
The RAINFOR database: monitoring forest biomass and dynamics 总被引:1,自引:0,他引:1
Problem: Data from over 100 permanent sample plots which have been studied for 10–20 years need a suitable system for storage which allows simple data manipulation and retrieval for analysis. Methods: A relational database linking tree records, taxonomic nomenclature and corresponding environmental data has been built in MS Access as part of the RAINFOR project. Conclusion: The database allows flexible and long‐term use of a large amount of data: more than 100 tree plots across Amazonia, incorporating over 80 000 records of individual trees and over 300 000 total records of tree diameter measurements from successive censuses. The database is designed to enable linkages to existing soil, floristic or plant‐trait databases. This database will be a useful tool for exploring the impact of environmental factors on forest structure and dynamics at local to continental scales, and long term changes in forest ecology. As an early example of its potential, we explore the impact of different methodological assumptions on estimates of tropical forest biomass and carbon storage. 相似文献
8.
William Russell 《BMJ (Clinical research ed.)》1985,290(6485):1914
9.
The effects of mammalian gonadotropins, methyltestosterone and partially purified salmon gonadotropin on spermiation and oocyte maturation were studied in adult grey mullet. Methyltestosterone was a potent spermiating agent in both prespawning and spawning trials. The most effective dose was 5 mg/100 g body weight. Human chorionic gonadotropin (HCG) was moderately effective at a dose rate of 20 IU/100 g body weight. Both hormones blocked resorption of milt in captive animals. The HCG, FSH/LH combination, Synahorin+mullet pituitary homogenate, and partially purified salmon gonadotropin were equally effective, at the doses used, in inducing oocyte maturation and preventing onset of atrophy before completion of vitellogenesis. Atrophy occurred in all experimental fish at mean oocyte diameter of 750 μ. The significance of this finding is discussed. (Oceanic Institute Contribution No. 98). 相似文献
10.