全文获取类型
收费全文 | 115560篇 |
免费 | 9235篇 |
国内免费 | 39篇 |
出版年
2021年 | 1255篇 |
2019年 | 993篇 |
2018年 | 1669篇 |
2017年 | 1533篇 |
2016年 | 2142篇 |
2015年 | 2589篇 |
2014年 | 3033篇 |
2013年 | 4116篇 |
2012年 | 4737篇 |
2011年 | 4729篇 |
2010年 | 3397篇 |
2009年 | 2944篇 |
2008年 | 4171篇 |
2007年 | 4127篇 |
2006年 | 3860篇 |
2005年 | 3700篇 |
2004年 | 3595篇 |
2003年 | 3417篇 |
2002年 | 3219篇 |
2001年 | 4561篇 |
2000年 | 4292篇 |
1999年 | 3413篇 |
1998年 | 1283篇 |
1997年 | 1202篇 |
1996年 | 1064篇 |
1995年 | 946篇 |
1994年 | 944篇 |
1993年 | 947篇 |
1992年 | 2548篇 |
1991年 | 2541篇 |
1990年 | 2581篇 |
1989年 | 2305篇 |
1988年 | 2154篇 |
1987年 | 2067篇 |
1986年 | 1876篇 |
1985年 | 1902篇 |
1984年 | 1586篇 |
1983年 | 1358篇 |
1982年 | 1010篇 |
1979年 | 1482篇 |
1978年 | 1166篇 |
1977年 | 1050篇 |
1976年 | 1003篇 |
1975年 | 1176篇 |
1974年 | 1282篇 |
1973年 | 1355篇 |
1972年 | 1198篇 |
1971年 | 1058篇 |
1970年 | 943篇 |
1969年 | 968篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
S F Silverton O A Adebanjo B S Moonga E M Awumey T Malinski M Zaidi 《Biochemical and biophysical research communications》1999,259(1):73-77
Nitric oxide (NO) triggers marked osteoclast retraction which closely resembles that due to Ca2+. The effect of Ca2+ has been attributed to a stimulated release of NO. Here, we show for the first time, by direct measurement with a microsensor, that osteoclasts do indeed produce NO and that this production is enhanced by a high Ca2+. We also show that the Ca2+ ionophore, A23187, mimics the latter. Furthermore, osteoclasts on dentine produce more NO than osteoclasts on glass and NO release from dentine-plated osteoclasts is much less sensitive to stimulation by Ca2+. Finally, the microsomal Ca2+ store-depleting agent, thapsigargin, attenuates NO release only from osteoclasts on glass, suggesting that stored Ca2+ has the dominant effect in modulating NO release from non-resorbing cells. NO is a powerful inhibitor of bone resorption: a direct demonstration of its production is therefore strong evidence for a role in modulating osteoclast function. 相似文献
82.
A G Buiavykh O S Medvedev A F Stukanov 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(7):28-30
The effect of low-frequency magnetic field (MF) on systemic blood pressure has been studied in chronic experiments on 21 spontaneously hypertensive rats. The animals' kidney area was exposed to MF (induction value 30T). Direct blood pressure measurements have revealed an antihypertensive effect. 相似文献
83.
J M Katz W G Laver D O White E M Anders 《Journal of immunology (Baltimore, Md. : 1950)》1985,134(1):616-622
The recognition of influenza virus hemagglutinin (HA) by T lymphocytes was examined by assaying the T cell proliferative response of influenza virus-primed T cells to purified HA of different influenza A subtypes or to isolated heavy (HA1) or light (HA2) polypeptide chains of the HA molecule. The proliferative response to HA was dependent on the activation of an Ly-1+2- subset of T cells and required the presence of nylon wool-adherent, radiation-resistant accessory cells. T cells from mice primed by infection with one strain of type A influenza virus cross-reacted with other purified HA not only of the same subtype as the priming virus but also of serologically distinct subtypes of influenza A (but not B) virus. The response of virus-primed T cells to the homologous HA or to HA of the same subtype was shown to involve recognition of determinants on both the HA1 and the HA2 chains. The recognition of HA of different subtype by cross-reactive T cells appeared to be directed predominantly to determinants on HA2. Because the antibody response to influenza virus HA is not cross-reactive between subtypes and is directed predominantly to determinants on HA1, the present results indicate that at least some of the determinants on HA recognized by T cells are different from those recognized by B cells and that the HA2 chain may be involved primarily in stimulation of T cell rather than B cell immunity. 相似文献
84.
85.
86.
87.
Kolomeyets N. L. Syslonova O. V. Smirnova S. L. Peshkin E. A. Roshchevskaya I. M. 《Journal of Evolutionary Biochemistry and Physiology》2021,57(6):1351-1362
Journal of Evolutionary Biochemistry and Physiology - Changes in bioelectrical impedance of the myocardium and liver were revealed in male Wistar rats chronically exposed to doxorubicin.... 相似文献
88.
Jin Wei Mia Madel Alfajaro Peter C. DeWeirdt Ruth E. Hanna William J. Lu-Culligan Wesley L. Cai Madison S. Strine Shang-Min Zhang Vincent R. Graziano Cameron O. Schmitz Jennifer S. Chen Madeleine C. Mankowski Renata B. Filler Neal G. Ravindra Victor Gasque Fernando J. de Miguel Ajinkya Patil Huacui Chen Craig B. Wilen 《Cell》2021,184(1):76-91.e13
- Download : Download high-res image (212KB)
- Download : Download full-size image
89.
Targeting of many transmembrane proteins to post-Golgi compartments is dependent on cytoplasmically exposed sorting signals. The most widely used signals conform to the tyrosine- or the leucine-based motifs. Both types of signals have been implicated in protein localization to the same intracellular compartments, but previous results from both cell-free experiments and studies of transfected cell lines have indicated that the two types of signals interact with separate components of the sorting machinery. We have overexpressed several transmembrane proteins in stably transfected Madin-Darby canine kidney cells using an inducible promoter system. Overexpression of proteins containing tyrosine- or leucine-based sorting signals resulted in reduced internalization of the transferrin receptor, whereas recycling and polarized distribution was not influenced. Our results indicate that proteins with tyrosine- and leucine-based sorting signals can be transported along common saturable pathways. 相似文献
90.