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   2226篇
  免费   137篇
  国内免费   3篇
  2024年   2篇
  2023年   15篇
  2022年   39篇
  2021年   101篇
  2020年   32篇
  2019年   42篇
  2018年   79篇
  2017年   53篇
  2016年   84篇
  2015年   98篇
  2014年   147篇
  2013年   175篇
  2012年   204篇
  2011年   234篇
  2010年   131篇
  2009年   127篇
  2008年   140篇
  2007年   121篇
  2006年   108篇
  2005年   76篇
  2004年   88篇
  2003年   60篇
  2002年   58篇
  2001年   17篇
  2000年   17篇
  1999年   9篇
  1998年   5篇
  1997年   2篇
  1996年   3篇
  1995年   9篇
  1994年   4篇
  1993年   9篇
  1992年   5篇
  1991年   4篇
  1990年   6篇
  1989年   4篇
  1988年   7篇
  1987年   7篇
  1986年   3篇
  1985年   7篇
  1983年   7篇
  1981年   2篇
  1979年   4篇
  1978年   4篇
  1975年   4篇
  1974年   2篇
  1973年   2篇
  1970年   2篇
  1969年   3篇
  1968年   1篇
排序方式: 共有2366条查询结果,搜索用时 15 毫秒
971.
972.
973.
Presence of one or more digit is called as polydactyly and may manifest singly or with other genetic disorders. The frequency of polydactyly varies widely among populations. It can occur as an isolated condition or as a feature of a congenital condition. Polydactyly is a rare condition, but still rare is in form of triple great toes. We describe a case in a 4-year-old child diagnosed as triphalangism foot with no other obvious visible anomaly. Osteoplasty-combined surgery, which was ideal for anatomical reconstruction. In a 16-month follow-up period child recovered very well.  相似文献   
974.
Tamoxifen is a nonsteroidal estrogen-receptor modulator widely used in the treatment of breast cancer. Apoptosis has been reported to be a major mechanism for its antitumor effect. In the current studies, an endeavor was made to investigate the efficacy of vesicularly encapsulated tamoxifen on human breast cancer MCF-7 cells. Phospholipid-based vesicular systems viz. conventional liposomes and elastic-membrane liposomes were employed to encapsulate the drug. The MTT colorimetric assay was used to determine the efficacy of the tested formulations. The results demonstrated composition-dependent strong inhibition in the viability of MCF-7 cells with encapsulated tamoxifen vis-à-vis free drug. The encouraging findings from the current work construe immense potential of the lipid-based vesicular systems in the treatment of breast cancer.  相似文献   
975.
976.
For novel biotechnology-based termite control, we developed a cellulose bait containing freeze-dried genetically engineered yeast which expresses a protozoacidal lytic peptide attached to a protozoa-recognizing ligand. The yeast acts as a ‘Trojan-Horse’ that kills the cellulose-digesting protozoa in the termite gut, which leads to the death of termites, presumably due to inefficient cellulose digestion. The ligand targets the lytic peptide specifically to protozoa, thereby increasing its protozoacidal efficiency while protecting non-target organisms. After ingestion of the bait, the yeast propagates in the termite''s gut and is spread throughout the termite colony via social interactions. This novel paratransgenesis-based strategy could be a good supplement for current termite control using fortified biological control agents in addition to chemical insecticides. Moreover, this ligand-lytic peptide system could be used for drug development to selectively target disease-causing protozoa in humans or other vertebrates.  相似文献   
977.
978.
Retroviral replication proceeds through an obligate integrated DNA provirus, making retroviral vectors attractive vehicles for human gene-therapy. Though most of the host cell genome is available for integration, the process of integration site selection is not random. Retroviruses differ in their choice of chromatin-associated features and also prefer particular nucleotide sequences at the point of insertion. Lentiviruses including HIV-1 preferentially integrate within the bodies of active genes, whereas the prototypical gammaretrovirus Moloney murine leukemia virus (MoMLV) favors strong enhancers and active gene promoter regions. Integration is catalyzed by the viral integrase protein, and recent research has demonstrated that HIV-1 and MoMLV targeting preferences are in large part guided by integrase-interacting host factors (LEDGF/p75 for HIV-1 and BET proteins for MoMLV) that tether viral intasomes to chromatin. In each case, the selectivity of epigenetic marks on histones recognized by the protein tether helps to determine the integration distribution. In contrast, nucleotide preferences at integration sites seem to be governed by the ability for the integrase protein to locally bend the DNA duplex for pairwise insertion of the viral DNA ends. We discuss approaches to alter integration site selection that could potentially improve the safety of retroviral vectors in the clinic.  相似文献   
979.
980.
Cucumber mosaic virus (CMV) epidemics occur worldwide in tomato fields, resulting in severe yield losses. Presently, no resistant commercial cultivars are available, and therefore we consider genetic transformation as an attractive alternative to achieve resistance against this disease.  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