全文获取类型
收费全文 | 10177篇 |
免费 | 887篇 |
国内免费 | 9篇 |
出版年
2022年 | 57篇 |
2021年 | 110篇 |
2020年 | 53篇 |
2019年 | 80篇 |
2018年 | 108篇 |
2017年 | 95篇 |
2016年 | 167篇 |
2015年 | 269篇 |
2014年 | 347篇 |
2013年 | 479篇 |
2012年 | 564篇 |
2011年 | 576篇 |
2010年 | 391篇 |
2009年 | 368篇 |
2008年 | 572篇 |
2007年 | 557篇 |
2006年 | 546篇 |
2005年 | 559篇 |
2004年 | 523篇 |
2003年 | 549篇 |
2002年 | 504篇 |
2001年 | 142篇 |
2000年 | 143篇 |
1999年 | 191篇 |
1998年 | 172篇 |
1997年 | 139篇 |
1996年 | 127篇 |
1995年 | 111篇 |
1994年 | 112篇 |
1993年 | 99篇 |
1992年 | 117篇 |
1991年 | 116篇 |
1990年 | 116篇 |
1989年 | 111篇 |
1988年 | 111篇 |
1987年 | 70篇 |
1986年 | 81篇 |
1985年 | 93篇 |
1984年 | 112篇 |
1983年 | 93篇 |
1982年 | 112篇 |
1981年 | 97篇 |
1980年 | 88篇 |
1979年 | 65篇 |
1978年 | 75篇 |
1977年 | 83篇 |
1976年 | 61篇 |
1975年 | 66篇 |
1974年 | 63篇 |
1973年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
An earlier report (1) of an adverse effect of high doses of oxytocin on human memory included results of studies on women receiving oxytocin as part of the treatment to induce 2nd trimester therapeutic abortion. These women served as their own controls. We have now been able to study a group of women who have been treated in all ways like the original group, with the exception that they did not receive oxytocin. The results from this external control corroborate the finding that oxytocin affected memory. 相似文献
2.
Natalia Ermak Bernard Lacour Françoise Goirand Stéphanie Vicca 《Biochemical and biophysical research communications》2010,393(4):783-787
We compared the apoptotic mechanism involved in U937 human monocytic cell line in presence of oxidized low-density lipoproteins (oxLDL) obtained after treatment with hypochlorous acid (HOCl) or copper (Cu).Both types of oxLDL induced U937 apoptotic cell death via the mitochondrial pathway. In contrast to HOCl-oxLDL, Cu-oxLDL induced apoptosis via a caspase-independent mechanism, with no activation of pro-caspase-3, but via the release of apoptosis inducing factor (AIF) from mitochondria.The apoptotic program of the monocyte differs depending on the mode of LDL oxidation, based on differences in the oxidatively modified components of the two oxLDL types. 相似文献
3.
4.
5.
Bernard Appiah 《CMAJ》2012,184(16):E831-E832
6.
The recurrence of influenza A epidemics has originally been explained by a “continuous antigenic drift” scenario. Recently, it has been shown that if genetic drift is gradual, the evolution of influenza A main antigen, the haemagglutinin, is punctuated. As a consequence, it has been suggested that influenza A dynamics at the population level should be approximated by a serial model. Here, simple models are used to test whether a serial model requires gradual antigenic drift within groups of strains with the same antigenic properties (antigenic clusters). We compare the effect of status based and history based frameworks and the influence of reduced susceptibility and infectivity assumptions on the transient dynamics of antigenic clusters. Our results reveal that the replacement of a resident antigenic cluster by a mutant cluster, as observed in data, is reproduced only by the status based model integrating the reduced infectivity assumption. This combination of assumptions is useful to overcome the otherwise extremely high model dimensionality of models incorporating many strains, but relies on a biological hypothesis not obviously satisfied. Our findings finally suggest the dynamical importance of gradual antigenic drift even in the presence of punctuated immune escape. A more regular renewal of susceptible pool than the one implemented in a serial model should be part of a minimal theory for influenza at the population level. 相似文献
7.
E. Backe G. Lotz U. Tittelbach H. Thurmer E. Gierke N. Kersten A. Bernard G. Wallenstein W. D. Schneider 《Biomarkers》2000,5(2):119-128
The inflammation markers alpha-1-antitrypsin (AAT), Clara cell protein (CC-16), soluble interleukin-2-receptor (IL-R) and the soluble adhesion molecule E-selectin, the intercellular adhesion molecule (ICAM-1) and the vascular adhesion molecule (VCAM-1) were determined in the serum of 195 salt-exposed miners to analyse dose-response relationships between markers and potash dust. Alpha-1-antitrypsin, Clara-cell protein, IL2-R, E-selectin and VCAM-1 were not changed by salt exposure, however the ICAM-1 level in the serum fell slightly as the salt exposure increased. This effect was strongest in the group of smokers, still visible in the group of ex-smokers, no effect was seen in non-smokers. Markers, with the exception of VCAM-1, were influenced by tobacco exposure. Since markers were not elevated in relation to salt dust exposure, the results do not support an inflammatory effect of potash dust on the respiratory system. 相似文献
8.
9.
10.
A new micronucleus test using peripheral blood erythrocytes of the newt Pleurodeles waltl to detect mutagens in fresh-water pollution 总被引:4,自引:0,他引:4
A model micronucleus test system using peripheral blood erythrocytes from larvae of Pleurodeles waltl is described. The most suitable larval stage for testing chemical treatments was determined. Larvae were reared in water containing one of the 4 compounds: benzo[a]pyrene (BaP), ethyl methanesulphonate (EMS), diethyl sulphate (DES) and N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Response curves as a function of treatment duration over a period of 16 days were plotted for 3 different concentrations of the 4 compounds in order to optimize conditions for a low dose micronucleus test. This model can be used as a monitoring system for the detection of fresh water pollution and can also be employed for clastogen screening of chemical compounds. The test is sensitive, reliable and easy to use. 相似文献