全文获取类型
收费全文 | 749681篇 |
免费 | 89098篇 |
国内免费 | 350篇 |
出版年
2018年 | 6441篇 |
2016年 | 8611篇 |
2015年 | 11845篇 |
2014年 | 13756篇 |
2013年 | 20256篇 |
2012年 | 22448篇 |
2011年 | 22918篇 |
2010年 | 15362篇 |
2009年 | 14326篇 |
2008年 | 20521篇 |
2007年 | 20994篇 |
2006年 | 19824篇 |
2005年 | 18909篇 |
2004年 | 18543篇 |
2003年 | 18177篇 |
2002年 | 17632篇 |
2001年 | 33673篇 |
2000年 | 34100篇 |
1999年 | 27344篇 |
1998年 | 9819篇 |
1997年 | 10497篇 |
1996年 | 10005篇 |
1995年 | 9251篇 |
1994年 | 9271篇 |
1993年 | 9290篇 |
1992年 | 23269篇 |
1991年 | 22664篇 |
1990年 | 22114篇 |
1989年 | 21854篇 |
1988年 | 20072篇 |
1987年 | 19249篇 |
1986年 | 18002篇 |
1985年 | 17995篇 |
1984年 | 14926篇 |
1983年 | 13034篇 |
1982年 | 10022篇 |
1981年 | 8884篇 |
1980年 | 8625篇 |
1979年 | 14368篇 |
1978年 | 11296篇 |
1977年 | 10226篇 |
1976年 | 9753篇 |
1975年 | 10651篇 |
1974年 | 11057篇 |
1973年 | 10964篇 |
1972年 | 9947篇 |
1971年 | 8998篇 |
1970年 | 7732篇 |
1969年 | 7365篇 |
1968年 | 6660篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
R G Pankov A A Uschewa B T Tasheva P T Petrov G G Markov 《Cell biology international reports》1985,9(11):1003-1011
A dominating protein fraction (p45) having molecular weight of 45000 and pI 5.45 was found in the intermediate filaments pellet obtained from rat liver besides the present cytokeratins. Peptide mapping and radioimmunological assays with antibodies against this protein and muscle actin proved that the p45 protein belongs to the actin group. Immunoelectron microscopy revealed that this protein is located on the liver intermediate filaments. By melting of the cytokeratin complexes in urea it was established that p45 protein is complexed with the low molecular weight cytokeratin. 相似文献
983.
A strain of 1,507 typised donors enables 15.97 average donors to be selected for a thrombocyte transfusion in one of 75 patients selected at random with HLA antibodies being previously determined (1 to 66 donors per patient). HLA compatible donors were found for 72 patients (97.33 per cent). More than 5 HLA compatible donors could be found for 58 patients. The high number of compatible donors is based on the fact that among 1,507 donors there were 156 HLA homozygotes and 556 donors with 3 HLA-A or B-antigens respectively. Compatibility in the ABO-system was not taken into account. 相似文献
984.
D. S. Coffman Ben H. Leichtling H. V. Rickenberg 《Journal of cellular biochemistry》1981,15(4):369-385
The phosphoproteins of Dictyostelium discoideum were compared at different stages of development by polyacrylamide gel electrophoresis. Certain phosphoproteins of vegetative amoebae were conserved while others appeared and disappeared during development. Four major phosphoproteins with apparent subunit molecular weights of 50,000, 47,000, 38,000, and 34,000 disappeared precociously in response to exogenous cAMP. Two membranal phosphoproteins, with apparent subunit molecular weights of 80,000 and 81,000, appeared precociously in response to added cAMP. One of these phosphoproteins, molecular weight of 80,000, has been identified tentatively as the “contact site A” glycoprotein. Another membranal protein, with apparent subunit molecular weight of 42,000, unaffected in its appearance by cAMP, has been identified tentatively as phosphoactin. 相似文献
985.
Synthesis of intrathecal interferon in systemic lupus erythematosus with neurological complications.
Intrathecal synthesis of interferon in the absence of viral or bacterial infection was detected during the occurrence of neurological complications in two patients with systemic lupus erythematosus. The interferons displayed characteristics similar to those observed in the sera of patients with the disease. No interferon inducing activity was detected in the cerebrospinal fluid or serum of the two patients. These observations support the hypothesis of a localised mechanism of interferon induction in systemic lupus erythematosus which includes the interaction of lymphocytes with damaged tissues. 相似文献
986.
THE EXPERIMENTAL STUDY OF VEGETATION 总被引:4,自引:3,他引:1
C. D. PIGOTT 《The New phytologist》1982,90(3):389-404
987.
988.
989.
Following arteriolar occlusion, tissue oxygen concentration decreases and anoxic tissue eventually develops. Although anoxia
first appears in the region most distal to the capillary at the venous end, it eventually spreads throughout the entire region
of supply. In this paper the changing oxygen concentration, from the time of occlusion until the tissue is entirely anoxic,
is examined mathematically. The equations governing oxygen transport to tissue are solved by iterating a nonlinear integral
equation. This solution is valid until anoxia first appears. After anoxia develops it is necessary to solve a moving boundary
problem. This is done using the method of matched asymptotic expansions, and accurate solutions are obtained for a wide range
of physiological conditions. 相似文献
990.