首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1215篇
  免费   118篇
  国内免费   155篇
  2023年   15篇
  2022年   29篇
  2021年   54篇
  2020年   32篇
  2019年   32篇
  2018年   39篇
  2017年   37篇
  2016年   31篇
  2015年   49篇
  2014年   59篇
  2013年   91篇
  2012年   88篇
  2011年   72篇
  2010年   67篇
  2009年   57篇
  2008年   50篇
  2007年   62篇
  2006年   43篇
  2005年   44篇
  2004年   61篇
  2003年   43篇
  2002年   41篇
  2001年   33篇
  2000年   42篇
  1999年   28篇
  1997年   14篇
  1996年   9篇
  1995年   12篇
  1994年   11篇
  1993年   8篇
  1992年   23篇
  1991年   7篇
  1990年   15篇
  1989年   17篇
  1988年   9篇
  1987年   14篇
  1986年   8篇
  1985年   11篇
  1984年   6篇
  1983年   8篇
  1982年   8篇
  1981年   6篇
  1980年   7篇
  1979年   17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1488条查询结果,搜索用时 375 毫秒
1.
2.
3.
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   
4.
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   
5.
6.
7.
田螺科五种螺的核型研究   总被引:2,自引:0,他引:2  
以早期胚胎细胞为材料,用火焰干燥法制片,对分布于我国湖北省武汉市近郊的常见田螺科(Viviparidae)五种螺的核型进行了分析。结果:两种圆田螺的染色体数和国外报道的同一属的种类的一致。而三种环棱螺的染色体数,则较国外报道的另两种的少得多。在铜锈环棱螺的核型中,其m组的第一对和sm组的第四对染色体上,具有明显的随体,出现频率甚高。  相似文献   
8.
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   
9.
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   
10.
鲴亚科(Xenocyprininae)鱼类多为中小型鱼类,常见于江河湖泊等较宽阔的水域中,我国长江、黑龙江、黄河及珠江诸流域皆有分布,共有10种,隶属4个属(伍献文等,1964)。迄今尚未见有该亚科鱼类染色体组型的研究报道。本文是对其中三属四种鱼的染色体组型的观察结果。这四种鱼是银鲴(Xenocypris argentea)、黄尾鲴(Xenocypris davidi)、细鳞斜颌鲴(Plagiognathops microlepis)和逆鱼(Acanthobrama simoni)。其中黄尾鲴和细鳞斜颌鲴均为新的淡水养殖鱼(沈德长等,1981;陈楚星,1979)。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号