全文获取类型
收费全文 | 475451篇 |
免费 | 48714篇 |
国内免费 | 233篇 |
出版年
2018年 | 4197篇 |
2016年 | 5590篇 |
2015年 | 7747篇 |
2014年 | 9140篇 |
2013年 | 13356篇 |
2012年 | 15021篇 |
2011年 | 15470篇 |
2010年 | 10468篇 |
2009年 | 9601篇 |
2008年 | 13742篇 |
2007年 | 14603篇 |
2006年 | 13831篇 |
2005年 | 13082篇 |
2004年 | 13191篇 |
2003年 | 12818篇 |
2002年 | 12467篇 |
2001年 | 17921篇 |
2000年 | 17775篇 |
1999年 | 14692篇 |
1998年 | 5757篇 |
1997年 | 5848篇 |
1996年 | 5541篇 |
1995年 | 5236篇 |
1994年 | 5118篇 |
1993年 | 5149篇 |
1992年 | 12740篇 |
1991年 | 12483篇 |
1990年 | 12485篇 |
1989年 | 12243篇 |
1988年 | 11569篇 |
1987年 | 10894篇 |
1986年 | 10208篇 |
1985年 | 10674篇 |
1984年 | 9002篇 |
1983年 | 7784篇 |
1982年 | 6234篇 |
1981年 | 5675篇 |
1980年 | 5330篇 |
1979年 | 8457篇 |
1978年 | 6700篇 |
1977年 | 6361篇 |
1976年 | 6029篇 |
1975年 | 6444篇 |
1974年 | 7057篇 |
1973年 | 6893篇 |
1972年 | 6331篇 |
1971年 | 5733篇 |
1970年 | 4993篇 |
1969年 | 4997篇 |
1968年 | 4644篇 |
排序方式: 共有10000条查询结果,搜索用时 460 毫秒
961.
G. N. Borisyuk R. M. Borisyuk A. B. Kirillov E. I. Kovalenko V. I. Kryukov 《Biological cybernetics》1985,52(5):301-306
A new method is proposed to analyse dependencies in point processes, which takes into account specific character of neuronal activity. Simulation modelling of neuronal network revealed that the estimated weight of connection depends monotonically on the value of the model synaptic strength. In contrast to the crosscorrelation, the method allows for nonlinear interconnections and does not require point processes to be stationary and samples to be large. Examples are presented of the method's application to neurophysiological data analysis. 相似文献
962.
The first appearance, the 12-year follow-up, and the autopsy of a patient with a strange soft-tissue tumor in the lower leg region are described. Although it was originally taken for a malignant synovial tumor, its peculiar distribution pattern, together with its histologic picture, confirmed the final diagnosis as an epithelioid sarcoma. 相似文献
963.
Promotion and inhibition of vesicle fusion by polylysine 总被引:1,自引:0,他引:1
Polylysine induced rapid aggregation of large unilamellar vesicles composed of phosphatidylcholine-cardiolipin (1:1 molar ratio) but not their fusion. Application of the terbium-dipicolinic acid fusion assay showed that addition of polylysine at nanomolar concentrations enabled a significant lowering of the Ca2+ threshold concentration for vesicle fusion from 9 to 1 mM. Analysis of the kinetics of fusion with a mass-action kinetic model showed that polylysine enhanced significantly the rate of aggregation but affected only slightly the rate of fusion per se. Maximal enhancement of overall fusion rates occurred at a charge ratio (polylysine/cardiolipin) of about 0.5. At larger polylysine concentrations, e.g., at charge ratios greater than 3, polylysine inhibited vesicle fusion. 相似文献
964.
965.
Abstract: Electroconvulsive shock (ECS) administrations repeated for 10 consecutive days cause an elevation in the opioid content of the rat brain. Two different endogenous opioids, enkephalin and humoral-endorphin, undergo independent changes that differ in both their time course and intracerebral localization. These metabolic changes parallel long-term behavioral modifications such as the development and dissipation of tolerance to the analgesic effect of ECS. The activation of two different, independent, endogenous opioid systems by ECS is in agreement with previous behavioral and pharmacological studies. 相似文献
966.
967.
968.
The influence of contact guidance on the orientation of colonies of subcultured vascular smooth muscle cells 总被引:1,自引:0,他引:1
Robert C. Buck 《In vitro cellular & developmental biology. Plant》1982,18(9):783-788
Summary Subcultures of smooth muscle cells derived from rat thoracic aorta were grown on plane plastic substrata and on plastic substrata
having ridges molded in them by a heated, ruled template. The cells were found to have a very high degree of contact guidance
when distributed sparsely on the ridged substrata. When the cell density increased multilayered, elongated colonies formed.
On plane substrata these were irregular, curved, and disposed in all directions. On the ridged substrata, however, the colonies
were straight, evenly spaced, and positioned at right angles to the ridges.
Supported by Grant MT1011 from the Medical Research Council of Canada. 相似文献
969.
970.