全文获取类型
收费全文 | 292971篇 |
免费 | 34571篇 |
国内免费 | 151篇 |
出版年
2018年 | 2399篇 |
2016年 | 3085篇 |
2015年 | 4034篇 |
2014年 | 4913篇 |
2013年 | 6735篇 |
2012年 | 7697篇 |
2011年 | 7906篇 |
2010年 | 5200篇 |
2009年 | 5030篇 |
2008年 | 7143篇 |
2007年 | 7319篇 |
2006年 | 7200篇 |
2005年 | 6919篇 |
2004年 | 6784篇 |
2003年 | 6614篇 |
2002年 | 6464篇 |
2001年 | 17258篇 |
2000年 | 17444篇 |
1999年 | 13301篇 |
1998年 | 3861篇 |
1997年 | 4127篇 |
1996年 | 3851篇 |
1995年 | 3487篇 |
1994年 | 3465篇 |
1993年 | 3540篇 |
1992年 | 10386篇 |
1991年 | 10316篇 |
1990年 | 9804篇 |
1989年 | 9635篇 |
1988年 | 8990篇 |
1987年 | 8356篇 |
1986年 | 7556篇 |
1985年 | 7407篇 |
1984年 | 5823篇 |
1983年 | 5074篇 |
1982年 | 3612篇 |
1981年 | 3179篇 |
1980年 | 3030篇 |
1979年 | 5348篇 |
1978年 | 4114篇 |
1977年 | 3749篇 |
1976年 | 3299篇 |
1975年 | 3776篇 |
1974年 | 3947篇 |
1973年 | 3891篇 |
1972年 | 3421篇 |
1971年 | 3183篇 |
1970年 | 2822篇 |
1969年 | 2741篇 |
1968年 | 2412篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
911.
R. Brändén T. Nilsson S. Styring 《Biochemical and biophysical research communications》1980,92(4):1297-1305
A sensitive and reliable method to determine the stereochemical composition of 3-phosphoglyceric acid is presented. Results obtained with this method show that 3-phosphoglyceric acid formed in the ribulose-1,5-bisphosphate carboxylase reaction is a mixture of 10% L-3-PGA and 90% D-3-PGA. 相似文献
912.
Nine schizophrenic patients participated in a study which explored whether EEG feedback techniques could effect changes in the EEG similar to those associated with neuroleptic-induced improvement. During five sessions, each patient was presented feedback signals which continuously refected the discrepancy between characteristics of the patient's EEG power spectral profile and spectral profile characteristics associated by past research with neuroleptic induced clinical improvement. Significant within-session changes were observed for two of three EEG power spectrum bands of interest. No significant session-to-session EEG changes were observed. The results suggest that the EEG of schizophrenics can be temporarily altered, using feedback techniques, in a way that mimics the EEG changes that have been shown to occur with neuroleptic induced clinical improvement.The authors are indebted to Turan M. Itil, John W. Fredrickson, Michael Madwed, and Irene B. Francis. Senior authorship is shared equally. 相似文献
913.
914.
T P Chernobel' T I Randmaa Z Ia Maksimova A A Shinkorenko V N Migunov 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1987,(11):88-90
A total of 218 batches of blood preparations produced from different raw materials have been studied by means of enzyme immunoassay kits (Abbott Laboratories, USA). The assays have revealed that the preparations under study are nonstandard with respect to the content and isolation rate of HBsAg, the marker of hepatitis B virus. These data necessitate search for the ways of improving the quality of blood preparations. 相似文献
915.
Identification of the functional site of erythrocyte protein 4.1 involved in spectrin-actin associations 总被引:23,自引:0,他引:23
I Correas T L Leto D W Speicher V T Marchesi 《The Journal of biological chemistry》1986,261(7):3310-3315
Peptides produced by mild chymotryptic digestion of human erythrocyte protein 4.1 mimic the ability of intact 4.1 to promote the binding of spectrin to F-actin. This complex-promoting activity was found to reside in an 8-kDa peptide which was fully functional when dissociated from other protein 4.1-derived peptides, indicating that noncovalent complexes of multiple peptides were not essential for activity. The 8-kDa peptide was incorporated into a ternary complex with spectrin and F-actin in approximately stoichiometric amounts. Amino acid composition and two-dimensional peptide mapping show that the 8-kDa active peptide is located within the 10-kDa region of protein 4.1 which contains a cAMP-dependent phosphorylated site. 相似文献
916.
917.
E S Revazova Iu N Solov'ev T M Khizhniakova T V Iudicheva 《Biulleten' eksperimental'no? biologii i meditsiny》1985,99(4):469-471
The authors describe human cancer strains established from 6 cell lines transplanted to nude mice and rats: cancer of the liver, colon, lung, bladder and Burkitt's lymphoma. In spite of a long history (for several years) of cell line transfers in vitro, on transplantation of tumor cells, nude animals established tumors histologically identical to the primary cancer. 相似文献
918.
P W Blick M W Flowers A K Marsden D H Wilson A T Ghoneim 《BMJ (Clinical research ed.)》1980,281(6233):111-112
A four-way, double-blind, prospective trial of treatment of abscesses by incision, curettage, and primary closure with and without antibiotic cover (clindamycin injection before operation or capsules after operation, or both) was conducted. There was no appreciable difference in mean healing time between the patients given both the antibiotic injection and the antibiotic capsules and those given the injection and placebo capsules, whereas healing times in those given the placebo injection and antibiotic capsules or placebo only were appreciably longer. Four of the patients who were not given the antibiotic injection developed bacteraemia; one patient who was given the antibiotic injection also developed a bacteraemia, but this was caused by clindamycin-resistant bacteria. These results show that a single injection of an effective antibiotic before operation is sufficient to protect the patient against bacteraemia and permit optimum healing. 相似文献
919.
920.