全文获取类型
收费全文 | 1225篇 |
免费 | 103篇 |
国内免费 | 2篇 |
出版年
2023年 | 8篇 |
2022年 | 19篇 |
2021年 | 46篇 |
2020年 | 22篇 |
2019年 | 13篇 |
2018年 | 42篇 |
2017年 | 19篇 |
2016年 | 25篇 |
2015年 | 57篇 |
2014年 | 57篇 |
2013年 | 95篇 |
2012年 | 88篇 |
2011年 | 66篇 |
2010年 | 50篇 |
2009年 | 43篇 |
2008年 | 38篇 |
2007年 | 61篇 |
2006年 | 42篇 |
2005年 | 45篇 |
2004年 | 59篇 |
2003年 | 38篇 |
2002年 | 34篇 |
2001年 | 28篇 |
2000年 | 34篇 |
1999年 | 25篇 |
1997年 | 14篇 |
1996年 | 6篇 |
1995年 | 15篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 22篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 16篇 |
1977年 | 5篇 |
1975年 | 10篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 12篇 |
1970年 | 8篇 |
排序方式: 共有1330条查询结果,搜索用时 15 毫秒
1.
2.
Magnetic field influence on unsteady free convection flow of a second grade fluid near an infinite vertical flat plate with ramped wall temperature embedded in a porous medium is studied. It has been observed that magnitude of velocity as well as skin friction in case of ramped temperature is quite less than the isothermal temperature. Some special cases namely: (i) second grade fluid in the absence of magnetic field and porous medium and (ii) Newtonian fluid in the presence of magnetic field and porous medium, performing the same motion are obtained. Finally, the influence of various parameters is graphically shown. 相似文献
3.
4.
Beneficial effects of n-hexane bark extract of Onosma echioides L. on diabetic peripheral neuropathy
Ambreen Shoaib Badruddeen Rakesh Kumar Dixit Magdah Ganash George Barreto Ghulam Md Ashraf Hefazat Hussain Siddiqui 《Journal of cellular biochemistry》2019,120(10):16524-16532
Onosma echioides Linn (Boraginaceae) is the most frequently used curative herb widely used for kidney obstruction, sciatic pain, and gout. The present study was designed to investigate the therapeutic effects of n-hexane bark extract of O. echioides (OE) L. root in vivo against Streptozotocin-induced diabetic neuropathy in SD rats. For in vivo activity, the experiment was categorized into five different groups (n = 5). Group-I was considered as nondiabetic/normal control (NC) treated with 0.5% carboxymethyl cellulose (CMC), Group II as diabetic control, Group-III, IV, and V served as diabetic treated with OE 50, OE 100, and pregabalin at a dose of 50, 100, and 10 mg/kg body weight, orally, respectively. Body weight, blood glucose, oral glucose tolerance test, behavioral studies (motor coordination test, thermal hyperalgesia, cold allodynia, locomotor activity, oxidative biomarkers (thio barbituric acid reactive substances [TBARS], superoxide dismutase [SOD], glutathione [GSH], and catalase), and histopathology of the sciatic nerve were performed. Treatment with OE showed a dose-dependent increase in neuroprotective activity by improving the myelination and decreasing the axonal swelling of nerve fibers. The verdicts of behavioral activities showed a remarkable effect on animals after the treatment of extract and standard drug pregabalin. In conclusion, our findings supported the traditional application of OE and explored its importance in the management of diabetic neuropathy. Additional clinical experiments may provide novel therapeutic drugs for diabetes and its complications. 相似文献
5.
Three peaks of methyltransferase activity specific for MNNG alkylated DNA have been identified from extracts of chemically adapted M. luteus. They are designated as TI to TIII in order to their elution from a Sephadex G-75 column. The first one of these peaks has been purified to homogeneity. TI, is an inducible, unusually salt resistant, heat labile protein which corrects O6-methylguanine in alkylated DNA by the transfer of the O6-alkyl group to a cysteine amino acid in the TI protein. There is a stoichiometric relationship between the loss of O6-methylguanine from the DNA and the production of S-methylcysteine. Partially purified TII & TIII proteins show specificity for O4-alkylthymine and methyl phosphotriesters respectively. The mode of repair by the isolated methyltransferases is similar yet there is no competition for substrate specificity. The apparent molecular weights of TI, TII & TIII proteins are 31Kd, 22Kd, and 13Kd respectively. 相似文献
6.
Eight strains of Neisseria meningitidis belonging to different serogroups were analysed for their virulence in mice and their release of outer membrane proteins into the medium during growth. All strains released proteins. No detectable lipopolysaccharide was observed. However, SDS-PAGE showed a heterogenicity in the protein number and profile among the different strains of N. meningitidis tested. 相似文献
7.
8.
9.
Plasmodium falciparum: gene structure and hydropathy profile of the major merozoite surface antigen (gp195) of the Uganda-Palo Alto isolate 总被引:13,自引:0,他引:13
S P Chang K J Kramer K M Yamaga A Kato S E Case W A Siddiqui 《Experimental parasitology》1988,67(1):1-11
The gene encoding the 195,000-Da major merozoite surface antigen (gp195) of the FUP (Uganda-Palo Alto) isolate of Plasmodium falciparum, a strain widely used for monkey vaccination experiments, has been cloned and sequenced. The translated amino acid sequence of the FUP gp195 protein is closely related to the sequences of corresponding proteins of the CAMP (Malaysia) and MAD-20 (Papua New Guinea) isolates and more distantly related to those of the Wellcome (West Africa) and K1 (Thailand) isolates, supporting the proposed allelic dimorphism of gp195 within the parasite population. The prevalence of dimorphic sequences within the gp195 protein suggests that many gp195 epitopes would be group-specific. Despite the extensive differences in amino acid sequence between gp195 proteins of these two groups, the hydropathy profiles of proteins representative of both groups are very similar. The conservation of overall secondary structure shown by the hydropathy profile comparison indicates that gp195 proteins of the various P. falciparum isolates are functionally equivalent. This information on the primary structure of the FUP gp195 protein will enable us to evaluate the possible roles of conserved, group-specific and variable epitopes in immunity to the blood stage of the malaria parasite. 相似文献
10.
R. K. Ghosh K. A. I. Siddiqui G. Mukhopadhyay Amit Ghosh 《Molecular & general genetics : MGG》1985,200(3):439-441
Summary Two lines of evidence suggest that a gene analogous to the recA gene of Escherichia coli exists in Vibrio cholerae and that its product serves a proteolytic function in the SOS response. Firstly, Southern blot hybridization using the recA gene of E. coli as a probe revealed a genomic sequence in V. cholerae which hybridized with the probe. Secondly, the SOS-like response in V. cholerae (as measured by beta phage induction) triggered by DNA damaging agents like Furazolidone could be blocked by Antipain, a protease inhibitor known to inhibit RecA protease action in E. coli. Maximal blocking effect of Antipain on beta phage induction occurred at 1 mM. At this concentration neither the viability of the host bacterium nor the lytic growth of a clear plaque mutant of the phage was affected by Antipain. 相似文献