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   895710篇
  免费   89687篇
  国内免费   1434篇
  986831篇
  2018年   18253篇
  2017年   16649篇
  2016年   17167篇
  2015年   15077篇
  2014年   17217篇
  2013年   24253篇
  2012年   30681篇
  2011年   38700篇
  2010年   29057篇
  2009年   24140篇
  2008年   32655篇
  2007年   34537篇
  2006年   23441篇
  2005年   22826篇
  2004年   23083篇
  2003年   22217篇
  2002年   21203篇
  2001年   38645篇
  2000年   38783篇
  1999年   30729篇
  1998年   10746篇
  1997年   11258篇
  1996年   10546篇
  1995年   9850篇
  1994年   9591篇
  1993年   9386篇
  1992年   24843篇
  1991年   24106篇
  1990年   23486篇
  1989年   22847篇
  1988年   21209篇
  1987年   19819篇
  1986年   18360篇
  1985年   18184篇
  1984年   15088篇
  1983年   12596篇
  1982年   9547篇
  1981年   8520篇
  1980年   7980篇
  1979年   13525篇
  1978年   10520篇
  1977年   9461篇
  1976年   8567篇
  1975年   9536篇
  1974年   10165篇
  1973年   10055篇
  1972年   9194篇
  1971年   8446篇
  1970年   7003篇
  1969年   6752篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Identification of bacteria of dairy origin using miniaturized test-systems   总被引:1,自引:1,他引:0  
One hundred and forty-four isolates of dairy origin were identified using a number of commercially available test kits. Agreement between these kits was acceptable for assignment of isolates to genera, but there was some variation between the kits for the identification of the isolates at specific level. The reasons for these variations are discussed. In terms of cost, ease of performance and accuracy, the identification systems manufactured by Roche Products Ltd (viz. the Oxi/Ferm tube and the Enterotube) are considered to be the best suited to the routine identification of dairy micro-organisms.  相似文献   
912.
913.
The study of the effect of gamma globulin introduced in different doses (0.5 and 0.25 ml/mg) in combination with Fermi rabies vaccine (observations on humans were made) and with cerebral rabies vaccine inactivated by UV irradiation (in animal experiments) demonstrated that the injection of the higher doses of gamma globulin resulted in lower geometrical mean of antibody titers. Therefore, in combined administration of rabies vaccine and gamma globulin for postexposure rabies prevention it is advisable to reduce the dose of gamma globulin by one-half.  相似文献   
914.
Summary Viral leukemogenesis in mice is frequently initiated by proviral activation of a highly conserved cellular gene called Pim-1. Here we report the chromosomal localization of the human homologue by Southern blot analyses of DNAs obtained from human-rodent somatic cell hybrids. The single copy human homologue was assigned to the 6pter-q12 segment.  相似文献   
915.
916.
We examined the relationships among reproductive hormone concentrations and bone mineral density (BMD) in 43 women runners classified as eumenorrheic (n = 24), oligomenorrheic (n = 8), or amenorrheic (n = 11). Results were compared with a eumenorrheic nonrunner control group (n = 11). Serum 17 beta-estradiol, progesterone, and dehydroepiandrosterone sulfate concentrations were determined in daily blood samples for 21 days, and integrated concentrations (areas under the curve) were calculated. BMD was assessed at the lumbar spine and proximal femur by dual-photon absorptiometry. As expected, 17 beta-estradiol, progesterone, and lumbar spine BMD were higher in the control and eumenorrheic runner groups than in the oligomenorrheic and amenorrheic runner groups (P less than 0.05). Progesterone concentration was significantly correlated with lumbar spine BMD in the eumenorrheic runners (r = 0.61). None of the steroid hormones was significantly related to BMD in the oligomenorrheic/amenorrheic group. The present data suggest that circulating levels of gonadal steroid hormones affect axial BMD in eumenorrheic runners.  相似文献   
917.
Fractionation of human erythrocyte membrane proteins was performed using a modification of two-dimensional gel electrophoresis described by P. O'Farrel with isoelectric point plotted against molecular mass. All major erythrocyte proteins, including high molecular weight proteins, such as spectrin and band 3 protein, identified by one-dimensional sodium dodecyl sulfate gel electrophoresis, were visualized by silver staining of two-dimensional gels. All in all about 50 polypeptides were distinguished on two-dimensional electrophoretic patterns. Preliminary protein map was developed.  相似文献   
918.
We evaluated in a rat model the effects of a homologous fibrin glue in reversing the effects of Adriamycin on adherence and take of skin grafts. A total of 40 male Fisher rats were used in the study. During the first phase of the experiment, the animals were assigned to either group I (N = 10) receiving normal saline or group II (N = 10) receiving 6 mg/kg Adriamycin by tail vein injection 24 hours before surgery. Skin grafts with and without fibrin glue were placed over wounds in the backs of the animals and adherence was measured at 24 and 48 hours. In the second phase (N = 20), the experiment was repeated, this time evaluating the total area of skin graft take at 7 days. Fibrin glue was found to increase adherence and take of skin grafts in all Adriamycin-treated animals.  相似文献   
919.
Antiserum to Z-DNA   总被引:13,自引:0,他引:13  
B Malfoy  M Leng 《FEBS letters》1981,132(1):45-48
  相似文献   
920.
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