全文获取类型
收费全文 | 575255篇 |
免费 | 47716篇 |
国内免费 | 1002篇 |
出版年
2018年 | 16165篇 |
2017年 | 14809篇 |
2016年 | 13284篇 |
2015年 | 7456篇 |
2014年 | 9018篇 |
2013年 | 12604篇 |
2012年 | 18285篇 |
2011年 | 27083篇 |
2010年 | 21514篇 |
2009年 | 17018篇 |
2008年 | 22601篇 |
2007年 | 24548篇 |
2006年 | 13582篇 |
2005年 | 13117篇 |
2004年 | 13537篇 |
2003年 | 13208篇 |
2002年 | 12885篇 |
2001年 | 24994篇 |
2000年 | 24964篇 |
1999年 | 19114篇 |
1998年 | 5687篇 |
1997年 | 5874篇 |
1996年 | 5422篇 |
1995年 | 4931篇 |
1994年 | 4872篇 |
1993年 | 4910篇 |
1992年 | 15050篇 |
1991年 | 15140篇 |
1990年 | 14637篇 |
1989年 | 14428篇 |
1988年 | 13444篇 |
1987年 | 12571篇 |
1986年 | 11413篇 |
1985年 | 11451篇 |
1984年 | 9067篇 |
1983年 | 7746篇 |
1982年 | 5385篇 |
1981年 | 4713篇 |
1980年 | 4565篇 |
1979年 | 8299篇 |
1978年 | 6407篇 |
1977年 | 5834篇 |
1976年 | 5408篇 |
1975年 | 6314篇 |
1974年 | 6763篇 |
1973年 | 6634篇 |
1972年 | 6156篇 |
1971年 | 5797篇 |
1970年 | 4829篇 |
1969年 | 4686篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
G V Kolusheva 《Arkhiv anatomii, gistologii i émbriologii》1987,93(7):10-15
The electron microscopic method has revealed early maturation of the protein-synthesizing apparatus of some cells, on the one hand, and underdevelopment of neuroblast volumes, appearance of artificial contacts, axonal degeneration and destruction in large trunks, on the other hand. Compensatory-restorative processes in the cell on the 14th and 21st days of the postnatal development result in a complete restoration of morphological organization of neurons and interneuronal connections in the hypothalamus of offspring of the morphine-dependent rats. 相似文献
992.
993.
M R Kopantseva M Z Liudvig I I Uspenski? N A Tamarina V A Tsatrian L I Korochkin 《Zhurnal obshche? biologii》1990,51(1):125-140
A comparative electrophoretic study or ejaculatory bulb proteins in 29 different Drosophila species has been carried out. In all analyzed species, ejaculatory bulb contains a major component (designated as PEB). It has molecular mass of 61-65 kDa in the species of virilis group, 33-36 kDa in species of obscura group, and 34-56 kDa in species of melanogaster group. Using immunoblotting technique, we have demonstrated that PEB is introduced into organs of female sex tract during mating. The nature and significance of revealed interspecific differences in PEB proteins has been discussed. 相似文献
994.
When the roots of Vicia faba L. beans were subjected to hypoxic stress, the activity of H+-ATPase on the peribacteroid membrane, as well as the transport of dicarboxylates (malate and succinate) mediated by this
enzyme, decreased. Since malate and succinate are the main carbon-containing metabolites involved in the energy supply to
bacteroids, this caused a change of the relation type from mutualism to commensalism, and the domination of the eukaryotes
over the prokaryotes consequently increased. 相似文献
995.
996.
S Ikei M Ogawa T Beppu C Ohara K Sakamoto H Sameshima H Arakawa Y Yamaguchi T Yamanaka S Kudo 《Cytokine》1992,4(6):581-584
In an attempt to investigate the interaction between the changes of cytokines and acute phase reactants after transcatheter arterial chemoembolization therapy (TACE), the levels of interleukin 6 (IL-6), interleukin 8 (IL-8), C-reactive protein (CRP) and pancreatic secretory trypsin inhibitor (PSTI) in the blood of patients with unresectable hepatocellular carcinoma (HCC) were measured. Before the therapy, serum IL-6 and plasma IL-8 levels were detectable in 77.8% and 28.5%, respectively, of patients with HCC. Levels of serum IL-6 and plasma IL-8 increased after TACE and reached a peak on day 3 in all patients (18/18) and in 87.5% of patients (12/14), respectively. Both blood levels of IL-6 and IL-8 reached a peak earlier than those of CRP and PSTI did after the therapy. When the maximal values of IL-6 were compared with those of CRP and PSTI, there were significant positive correlations (r = 0.63, P < 0.01 and r = 0.81, P < 0.01, respectively). Similarly, comparisons of the maximal values of IL-8 with those of CRP and PSTI gave a significant correlation (r = 0.68, P < 0.01 and r = 0.67, P < 0.05, respectively). However, no significant correlation was found between the elevation of IL-6 and IL-8. 相似文献
997.
A M Belles T J Montville B P Wasserman 《Journal of industrial microbiology & biotechnology》2000,24(1):71-74
Alcohol-extractable, hydrophobic zein proteins contaminate starch granule surfaces and can be removed by enzymatic digestion
with thermolysin. The goal of this research was to find practical alternatives to thermolysin that might be used during the
corn wet-milling process. All of the commercial thermostable alkaline proteases studied (SP 709, Neutrase, and Spezyme FAN)
removed the zein proteins from various types of cornstarch, as demonstrated by the lack of protein bands below 30 kDa under
the reducing conditions of SDS-PAGE gel. Each enzyme removed the zein proteins as effectively as thermolysin removed them.
However, the removal of the zein protein did not reduce the quantity of free fatty acids associated with the starch. Journal of Industrial Microbiology & Biotechnology (2000) 24, 71–74.
Received 27 May 1999/ Accepted in revised form 01 October 1999 相似文献
998.
999.
In vivo neutralization of TNF-alpha promotes humoral autoimmunity by preventing the induction of CTL. 总被引:3,自引:0,他引:3
C S Via A Shustov V Rus T Lang P Nguyen F D Finkelman 《Journal of immunology (Baltimore, Md. : 1950)》2001,167(12):6821-6826
Neutralization of TNF-alpha in humans with rheumatoid arthritis or Crohn's disease has been associated with the development of humoral autoimmunity. To determine the effect of TNF-alpha neutralization on cell-mediated and humoral-mediated responses, we administered anti-TNF-alpha mAb to mice undergoing acute graft-vs-host disease (GVHD) using the parent-into-F(1) model. In vivo neutralization of TNF-alpha blocked the lymphocytopenic features characteristic of acute GVHD and induced a lupus-like chronic GVHD phenotype (lymphoproliferation and autoantibody production). These effects resulted from complete inhibition of detectable antihost CTL activity and required the presence of anti-TNF-alpha mAb for the first 4 days after parental cell transfer, indicating that TNF-alpha plays a critical role in the induction of CTL. Moreover, an in vivo blockade of TNF-alpha preferentially inhibited the production of IFN-gamma and blocked IFN-gamma-dependent up-regulation of Fas; however, cytokines such as IL-10, IL-6, or IL-4 were not inhibited. These results suggest that a therapeutic TNF-alpha blockade may promote humoral autoimmunity by selectively inhibiting the induction of a CTL response that would normally suppress autoreactive B cells. 相似文献
1000.