全文获取类型
收费全文 | 298640篇 |
免费 | 27905篇 |
国内免费 | 281篇 |
专业分类
326826篇 |
出版年
2021年 | 2489篇 |
2018年 | 3337篇 |
2017年 | 3252篇 |
2016年 | 4546篇 |
2015年 | 5736篇 |
2014年 | 6698篇 |
2013年 | 9339篇 |
2012年 | 10460篇 |
2011年 | 10930篇 |
2010年 | 7453篇 |
2009年 | 6691篇 |
2008年 | 9459篇 |
2007年 | 9744篇 |
2006年 | 9128篇 |
2005年 | 8810篇 |
2004年 | 8613篇 |
2003年 | 8107篇 |
2002年 | 7961篇 |
2001年 | 13339篇 |
2000年 | 13241篇 |
1999年 | 10356篇 |
1998年 | 3480篇 |
1997年 | 3407篇 |
1996年 | 3320篇 |
1995年 | 3082篇 |
1994年 | 3000篇 |
1993年 | 2899篇 |
1992年 | 8214篇 |
1991年 | 7790篇 |
1990年 | 7881篇 |
1989年 | 7647篇 |
1988年 | 7055篇 |
1987年 | 6688篇 |
1986年 | 6012篇 |
1985年 | 6444篇 |
1984年 | 5061篇 |
1983年 | 4356篇 |
1982年 | 3116篇 |
1981年 | 2899篇 |
1980年 | 2628篇 |
1979年 | 4547篇 |
1978年 | 3543篇 |
1977年 | 3200篇 |
1976年 | 3102篇 |
1975年 | 3508篇 |
1974年 | 3857篇 |
1973年 | 3832篇 |
1972年 | 3302篇 |
1971年 | 3011篇 |
1970年 | 2682篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
N I Buianova V P Shchipkov K S Krivskaia A P Pekhov 《Biulleten' eksperimental'no? biologii i meditsiny》1990,110(9):298-301
The results of complementation analysis of nitrosoguanidine-induced mutants of F-like drd-plasmid pAP18-1 (Tc, ColV) testified to the existence of at least 3 tra regions (tra1, tra2, tra3) and regulating locus fin V in the genome of this plasmid. By means of molecular cloning of tra2 region and locus fin V of plasmid pAP18-1drd were located in Sall-fragment f5 (3.9 MD). 相似文献
992.
Elimination of apple stem grooving virus by chemotherapy and development of an immunocapture RT-PCR for rapid sensitive screening 总被引:1,自引:0,他引:1
D. JAMES P A TRYTTEN D J MACKENZIE G H N TOWERS C J FRENCH 《The Annals of applied biology》1997,131(3):459-470
Ombuin (7,4′-dimethyl quercetin) (10 μg ml-1, for 12 wk), glycyrrhizin/quercetin (80 μg ml-1and 10 μg ml-1respectively, for 18 wk), ribavirin (10 μg ml-1, for 12 wk) and quercetin/ribavirin (10 μg ml-1each, for 9–12 wk) reduced the titre of apple stem grooving virus (ASGV) when applied in vitro to infected tissue cultures of Nicotiana occidentalis obliqua Wheeler, and/or Malus domestica. ASGV was not detectable in both plant species after the quercitin/ribavirin treatment when tested by ISEM, herbaceous host indexing, RT-PCR, and immunocapture RT-PCR. A sensitive immunocapture RT-PCR procedure for the detection of ASGV was developed for the screening of treated samples to assess antiviral activity. 相似文献
993.
994.
A random walk amid the macromolecules. 总被引:1,自引:1,他引:0
K. E. van Holde 《Protein science : a publication of the Protein Society》1996,5(4):792-796
995.
A. Yu. Korolyuk A. V. Egorova I. E. Smelansky N. V. Filippova 《Contemporary Problems of Ecology》2008,1(1):49-58
The phytocenotic diversity of the Altai steppe piedmont is described. Plant communities were ordinated along the moisture gradient. The results were used to analyze the structure of vegetation of steppe hill massifs. Distribution of steppe vegetation over an ideal hill was simulated, and the main patterns of distribution were typified. 相似文献
996.
Lipid synthesis in permeabilized cultured rat hepatocytes 总被引:1,自引:0,他引:1
Hepatic lipid synthesis was verified and studied in lysolecithin-permeabilized cultured rat hepatocytes and compared to that of intact liver cells. Triacylglycerol synthesis in permeabilized cells incubated in the presence of glycerol 3-phosphate and long chain fatty acids approached that of intact hepatocytes. Similarly, phosphatidylcholine synthesis in permeable cells incubated in the presence of exogenous CDP-choline was similar to that of intact hepatocytes and at the expense of microsomal neutral lipid synthesis. Phosphatidic acid accumulation in lysolecithin-permeabilized liver cells was remarkably increased as compared to that of intact cells, and its synthesis was mostly accounted for by the activity of mitochondrial glycerol-3-phosphate acyltransferase. Mitochondrial-generated phosphatidate was found to migrate to the endoplasmic reticulum, thus establishing a novel lipid esterification pathway which begins in mitochondrial glycerol 3-phosphate acylation and results in microsomal triacylglycerol and phospholipid synthesis. The free access of permeabilized liver cells to substrates and modulators of lipid synthesis, while maintaining an overall synthetic pattern similar to that of intact hepatocytes, makes them a system of choice for studying hepatic lipid synthesis in general and the microsomal/mitochondrial distribution of fluxes in particular. 相似文献
997.
998.
Yellow lupine seeds were found to contain two proteins and a low molecular weight fraction possessing the ability to bind Mo, W and radionuclides from the Chernobyl nuclear power in vivo and the 185W isotope in vitro. These proteins differ in their electrophoretic mobility. The electrophoretically less mobile protein undergoes proteolytic degradation; the proteolytic product retains the ability to accumulate microelements. 相似文献
999.
1000.
Herman van der Kooij Ron Jacobs Bart Koopman Henk Grootenboer 《Biological cybernetics》1999,80(5):299-308
A model is presented to study and quantify the contribution of all available sensory information to human standing based
on optimal estimation theory. In the model, delayed sensory information is integrated in such a way that a best estimate of
body orientation is obtained. The model approach agrees with the present theory of the goal of human balance control. The
model is not based on purely inverted pendulum body dynamics, but rather on a three-link segment model of a standing human
on a movable support base. In addition, the model is non-linear and explicitly addresses the problem of multisensory integration
and neural time delays. A predictive element is included in the controller to compensate for time delays, necessary to maintain
erect body orientation. Model results of sensory perturbations on total body sway closely resemble experimental results. Despite
internal and external perturbations, the controller is able to stabilise the model of an inherently unstable standing human
with neural time delays of 100 ms. It is concluded, that the model is capable of studying and quantifying multisensory integration
in human stance control. We aim to apply the model in (1) the design and development of prostheses and orthoses and (2) the
diagnosis of neurological balance disorders.
Received: 25 August 1997 / Accepted in revised form: 8 December 1998 相似文献