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   332208篇
  免费   38151篇
  国内免费   140篇
  370499篇
  2018年   3233篇
  2017年   3038篇
  2016年   4307篇
  2015年   5788篇
  2014年   6792篇
  2013年   9637篇
  2012年   10635篇
  2011年   10775篇
  2010年   7267篇
  2009年   6466篇
  2008年   9242篇
  2007年   9689篇
  2006年   9016篇
  2005年   8578篇
  2004年   8630篇
  2003年   8293篇
  2002年   8146篇
  2001年   14525篇
  2000年   14543篇
  1999年   11634篇
  1998年   4121篇
  1997年   4191篇
  1996年   3991篇
  1995年   3858篇
  1994年   3860篇
  1993年   3737篇
  1992年   9892篇
  1991年   9471篇
  1990年   9285篇
  1989年   8998篇
  1988年   8404篇
  1987年   8032篇
  1986年   7255篇
  1985年   7357篇
  1984年   6077篇
  1983年   5331篇
  1982年   4199篇
  1981年   3717篇
  1980年   3533篇
  1979年   6125篇
  1978年   4576篇
  1977年   4286篇
  1976年   3985篇
  1975年   4323篇
  1974年   4665篇
  1973年   4726篇
  1972年   4365篇
  1971年   4075篇
  1970年   3444篇
  1969年   3347篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
931.
Summary The child with iminoglycinuria is in our observation. Hyperprolinuria was seen at 5 months by screening program. The child was repeatedly examined in the hospital and was seen last time at 16 months. IQ was 67, in the urine were excessive amounts of glycine, proline a hydroxyproline. In the blood aminoacids were in normal levels. In the child was noticed the same increase of proline in the blood as in the control child of the same age following loading test with L-proline, indicating normal intestinal absoption. Both parents and father's sister's 2-year-old mentally retarded child exhibit excessive glycinuria. The father, his sister, father's father, and grandfather are partialy, congenitaly deaf.  相似文献   
932.
933.
934.
935.
Large, uniform, skin-driven currents (20-40 muamp/cm2) leave the ends of limb stumps of post-metamorphic frogs (Rana pipiens) from about the first through the tenth day after amputation. However, right after amputation, while currents of comparable density may leave the periphery of the cut surface, current densities are greatly depressed in the center of this surface. We suggest that this depression is brought about by shunting through the subdermal lymph space (characteristic of anurans but not urodeles); continues in covert form after formation of a wound epithelium; and helps explain the ability of small, imposed currents to initiate frog limb regeneration.  相似文献   
936.
937.
Immunocytological investigations have been performed on semi-thin sections of human fetal pituitaries ranging in fetal age from 6 to 26 weeks. Corticotrophs can be revealed by anti-ACTH (1-24), anti-ACTH (17-39) and anti-beta MSH but not by anti-alpha MSH immunesera from the 8th week. Somatotrophs are revealed with anti-human STH from 9th week. Differentiating cells containing only alpha subunits of glycoproteic hormones are present from 8th to 12th week. At 13th week beta subunits of TSH can be revealed immunocytologically in thyreotrophs. Beta subunits of LH or FSH can be detected in same gonadotrophic cells only from 15th week.  相似文献   
938.
Cytogenetic studies were done on bone marrow cells and peripheral lymphocytes of four patients (three with acute nonlymphocytic leukemia, one with aplastic anemia) at various intervals up to 861 days after total-body X irradiation (TBI) at doses between 4.5 and 10 Gy (450-1000 rad) followed by syngeneic or allogeneic bone marrow transplantation. Whereas no radiation-induced aberrations could be found in the bone marrow, apart from a transient finding in the patient with the lowest radiation dose, aberrant metaphases were seen in the peripheral lymphocytes of three patients in the range from 2.5 to 46% even at 861 days after the exposure. There were no demonstrable aberrations related to TBI in the only patient developing graft-versus-host disease. The dicentric yield as determined in the aberrant metaphases with 46 centromeres ranged between 3.4 +/- 1.3 and 4.9 +/- 0.4. In one patient it was demonstrated by BUdR-labeling that after 10 Gy (1000 rad) TBI the surviving and heavily damaged lymphocytes can go into cell cycle and reach at least the third mitosis. The percentage of aberrant cells diminished by about 25% at each mitotic division.  相似文献   
939.
940.
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