全文获取类型
收费全文 | 887599篇 |
免费 | 94331篇 |
国内免费 | 568篇 |
出版年
2021年 | 7038篇 |
2018年 | 9611篇 |
2017年 | 8945篇 |
2016年 | 12901篇 |
2015年 | 18062篇 |
2014年 | 20469篇 |
2013年 | 28819篇 |
2012年 | 32763篇 |
2011年 | 32777篇 |
2010年 | 22034篇 |
2009年 | 19474篇 |
2008年 | 28657篇 |
2007年 | 29229篇 |
2006年 | 27354篇 |
2005年 | 26282篇 |
2004年 | 25932篇 |
2003年 | 24750篇 |
2002年 | 23670篇 |
2001年 | 39417篇 |
2000年 | 39622篇 |
1999年 | 31530篇 |
1998年 | 11202篇 |
1997年 | 11606篇 |
1996年 | 10882篇 |
1995年 | 10193篇 |
1994年 | 9922篇 |
1993年 | 9622篇 |
1992年 | 25497篇 |
1991年 | 24659篇 |
1990年 | 23984篇 |
1989年 | 23304篇 |
1988年 | 21624篇 |
1987年 | 20141篇 |
1986年 | 18689篇 |
1985年 | 18606篇 |
1984年 | 15442篇 |
1983年 | 12912篇 |
1982年 | 9808篇 |
1981年 | 8772篇 |
1980年 | 8203篇 |
1979年 | 13860篇 |
1978年 | 10782篇 |
1977年 | 9704篇 |
1976年 | 8804篇 |
1975年 | 9781篇 |
1974年 | 10426篇 |
1973年 | 10316篇 |
1972年 | 9167篇 |
1971年 | 8394篇 |
1970年 | 7178篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
881.
Using pancreatic RNAase and RNAase from Act. rimosus as models, the effect of modification by azocombination on the catalytic properties of enzymes were studied. It was shown that RNAases binding to soluble dextran did not cause any significant changes in their major catalytic properties, when polymeric RNA was used as a substrate. At the same time, the physico-chemical properties of the modified enzymes may result in changes in the catalytic properties in a reaction with low molecular weight substrates. Evidence for this observation can be obtained from the increase in the synthetic activity of modified pancreatic RNAase as compared to the hydrolase activity in the dinucleotide synthesis reaction. 相似文献
882.
883.
M Tachibana H Morioka M Machino F Mizukoshi O Mizukoshi T Yoshioka 《Histochemistry》1985,82(2):197-199
Triphosphoinositide (TPI), an aminoglycoside receptor and a possible regulator of cationic permeation through its ability to bind with Ca++, was localized by the protein-A gold technique in vestibular sensory epithelia using an antibody highly specific to TPI. TPI was detected on the stereocilia, kinocilia, and cuticular plate of hair cells, and in the reticular membrane of supporting cells. The cilia of hair cells are damaged by aminoglycosides at a relatively early stage of toxicity. Ca++-regulated bioactivity in this area is probably involved. 相似文献
884.
S. Goldenberg J.M. Salles V.T. Contreras M.P.Lima Franco A.M. Katzin W. Colli C.M. Morel 《FEBS letters》1985,180(2):265-270
The cell-free translation products of polyribosomal and post-polyribosomal mRNAs from the non-infective epimastigotes and the infective metacyclic trypomastigotes of the parasitic protozoan Trypanosoma cruzi were compared by two-dimensional polyacrylamide gel electrophoresis. The result show that although many polypeptides are conserved, quantitative and qualitative differences are observed between both differentiation stages. The results also indicate the existence of post-polyribosomal mRNAs in equilibrium with polyribosomal counterparts. The immunoprecipitation of the in vitro synthesized polypeptides with chagasic human serum and the serum raised against an 85-kDa glycoprotein (P2-WGA), potentially involved in the process of T. cruzi penetration into mammalian cells, shows that while the chagasic serum recognizes the same 72-kDa, 68-kDa and 46-kDa polypeptides in both differentiation stages, the anti-P2-WGA serum immunoprecipitates a single 48-kDa polypeptide from in vitro translation products of metacyclic trypomastigotes. 相似文献
885.
A range of wheat cultivars with resistance factors effective against Puccinia recondita f. sp. tritici was studied to investigate the mode of action and expression of resistance at first and third seedling leaf stages. In most cultivars, resistance to isolate 74/2 resulted in extremely low levels of infection, apparently linked with a predominantly hypersensitive response by the host. In seedlings of cultivars Mans Fundin and Sterna, however, race-specific resistance was expressed as increased pathogen latent period and intermediate infection levels. 相似文献
886.
A Rhalem K Bekhti C Bourdieu G Luffau P Péry 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1989,309(1):19-23
Proteins are released from the surface of sporozoites of Eimeria falciformis during their in vitro incubation in a detergent solution. Some of these proteins reacted with antibodies from infected mice and specifically stimulated the proliferation of mesenteric lymph node cells of these mice. Oral immunization of mice with liposome encapsulated sporozoite surface antigens protected mice against a challenge infection. Two proteins (M.W. 27 and 180 K) induced an antibody synthesis in these vaccinated mice. 相似文献
887.
888.
A Levva G Schwartsmann L C Boeije H M Pinedo F de Waal 《Biochemical and biophysical research communications》1986,141(2):629-635
In the original HL-60 cells (HL-60-S) and an HL-60 subline (HL-60-R) respectively susceptible and resistant to induction of differentiation by retinoic acid or dimethyl sulfoxide, 5-aza-2'-deoxycytidine inhibited growth equally but induced differentiation to a greater extent in HL-60-S. Flow cytometry showed that 5-aza-2'-deoxycytidine produced in both HL-60 lines an increased proportion of cells in G2+M rather than G0/G1 as with retinoic acid. 5-aza-2'-deoxycytidine may have a differentiation-inducing effect in HL-60 provided cells have the competence to differentiate, indicating the importance of an alternate mechanism of action. 相似文献
889.
Glycosylated haemoglobin (HbA1) was measured in seven insulin-dependent diabetic patients before, during, and after a seven-day period of monitored poor control. There was considerable individual variation in the pattern and degree of change in HbA1 concentration induced by poor control and the time when it occurred. Greater increases in HbA1 were seen during the period of metabolic derangement than in the subsequent two months. More information is required before HbA1 estimations are widely used clinically to monitor control in individual diabetics. 相似文献
890.
M N Diachina L T Sukhenko A A Iushchenko G A Ermolin 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1985,(1):64-68
Diagnostic test systems for the detection of IgG and IgM to Mycobacterium leprae in the blood sera of leprosy patients and armadillos experimentally infected with M. leprae have been developed on the basis of the indirect immunoperoxidase assay. The possibility has been shown of prognosing the activity of the leprotic process in leprosy patients and the results of the experimental infection of armadillos by the dynamic increase of antibody reactions with the development of the infection. 相似文献