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   146601篇
  免费   149916篇
  国内免费   45752篇
  342269篇
  2022年   3921篇
  2021年   4895篇
  2020年   4370篇
  2019年   6402篇
  2018年   5432篇
  2017年   4762篇
  2016年   5412篇
  2015年   6538篇
  2014年   8203篇
  2013年   7998篇
  2012年   9894篇
  2011年   10240篇
  2010年   10006篇
  2009年   14726篇
  2008年   9392篇
  2007年   8753篇
  2006年   7518篇
  2005年   6648篇
  2004年   5832篇
  2003年   5063篇
  2002年   5355篇
  2001年   6301篇
  2000年   3885篇
  1999年   7809篇
  1998年   9424篇
  1997年   9490篇
  1996年   8806篇
  1995年   9053篇
  1994年   8415篇
  1993年   8049篇
  1992年   8065篇
  1991年   8067篇
  1990年   8823篇
  1989年   8055篇
  1988年   7327篇
  1987年   6460篇
  1986年   5949篇
  1985年   5363篇
  1984年   4154篇
  1983年   3351篇
  1982年   3692篇
  1981年   3307篇
  1980年   3193篇
  1979年   3322篇
  1978年   3029篇
  1977年   2944篇
  1976年   2771篇
  1973年   2529篇
  1972年   2859篇
  1971年   2616篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
Summary The frequency of large granular lymphocytes (LGL) in the peripheral blood of healthy persons (n=56) and breast cancer patients (31 cases with stage-I and -II disease and 42 cases with stage-III and -IV disease) was studied. The frequency of LGL in peripheral blood was significantly depressed in cancer patients, and particularly in patients with advanced breast cancer.  相似文献   
122.
The murine cytomegalovirus m02 gene family encodes putative type I membrane glycoproteins named m02 through m16. A subset of these genes were fused to an epitope tag and cloned into an expression vector. In transfected and murine cytomegalovirus-infected cells, m02, m04, m05, m06, m07, m09, m10, and m12 localized to cytoplasmic structures near the nucleus, whereas m08 and m13 localized to a filamentous structure surrounding the nucleus. Substitution mutants lacking the m02 gene (SMsubm02) or the entire m02 gene family (SMsubm02-16) grew like their wild-type parent in cultured cells. However, whereas SMsubm02 was as pathogenic as the wild-type virus, SMsubm02-16 was markedly less virulent. SMsubm02-16 produced less infectious virus in most organs compared to wild-type virus in BALB/c and C57BL/6J mice, but it replicated to wild-type levels in the organs of immunodeficient gamma(c)/Rag2 mice, lacking multiple cell types including natural killer cells, and in C57BL/6J mice depleted of natural killer cells. These results argue that one or more members of the m02 gene family antagonize natural killer cell-mediated immune surveillance.  相似文献   
123.
124.
Polypeptides released into the culture medium of herpesvirus sylvilagus-infected cells were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of extracellular fluid from [35S]methionine- and [3H]glucosamine-labeled cell cultures. Virus-induced glycoproteins 31, 32, and 33 (molecular weights of 62,000, 59,000, and 54,000, respectively) were the most abundant species and appeared predominantly in the culture medium. This observation, together with the known cell-associated nature of herpesvirus sylvilagus, suggested that virus-induced glycoproteins 31, 32, and 33 were specifically released. Immunization of rabbits with virus-induced glycoproteins 13 (molecular weight of 130,000) and 32 resulted in the production of antibodies that neutralized viral infectivity in vitro. Both antiserum to gp13 and antiserum to gp32 immunoprecipitated gp13, gp26, gp33a, gp45, and virus-induced polypeptide 39 (molecular weights of 130,000, 77,000, 49,000, 27,000, and 36,000, respectively) from [35S]methionine-labeled cell extracts as well as virus-induced glycoproteins 31, 32, and 33 from the culture medium. In addition, membrane immunofluorescence assays indicate that an antigen(s) reactive with anti-gp13/32 serum was located on the plasma membrane of infected cells.  相似文献   
125.
126.
Cell respiratory activity of protoplasts obtained from the wild type of Neurospora crassa and photoreceptor complex WCC—white collar 1 (wc-1) and white collar 2 (wc-2)—mutants of Neurospora crassa strains was investigated. Respiration inhibition by KCN in the presence of 25 mM succinate was similar in all strains and did not exceed 83–85% against control. The significant induction of KCN-resistant respiratory pathway occurred under 1% glucose oxidation in wc-1 and wc-2 mutants if compared with the wild type strains. The inhibitors of the main (cytochrome) pathway of electron transfer in mitochondria—1 mM KCN and antimycin A (4 μg/ml)—blocked the respiration rate of the protoplasts from N. crassa wild type by 75%, while the cell respiration of wc-1 and wc-2 strains was suppressed by approximately 50%. The specific inhibitor of alternative oxidase—10 mM salicylhydroxamic acid (SHAM)—in combination with the blockers of mitochondrial electron transfer chain caused the total suppression of respiratory activity of protoplasts in all studied strains. It is supposed that an increase of KCN-resistance in WCC mutants under glucose oxidation is connected with alternative oxidase activation as the result of failure in reception and signal transduction of active oxygen species.  相似文献   
127.
128.
129.
130.
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