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   225333篇
  免费   15101篇
  国内免费   49篇
  240483篇
  2021年   1800篇
  2018年   3147篇
  2017年   3042篇
  2016年   3687篇
  2015年   3257篇
  2014年   4493篇
  2013年   6399篇
  2012年   7629篇
  2011年   8160篇
  2010年   5784篇
  2009年   4934篇
  2008年   7291篇
  2007年   7586篇
  2006年   7273篇
  2005年   6784篇
  2004年   6942篇
  2003年   6657篇
  2002年   6623篇
  2001年   9300篇
  2000年   8967篇
  1999年   7000篇
  1998年   2146篇
  1997年   1965篇
  1996年   1834篇
  1992年   5479篇
  1991年   5685篇
  1990年   5652篇
  1989年   5626篇
  1988年   5223篇
  1987年   4866篇
  1986年   4444篇
  1985年   4679篇
  1984年   3697篇
  1983年   3026篇
  1982年   2013篇
  1981年   1722篇
  1980年   1727篇
  1979年   3339篇
  1978年   2576篇
  1977年   2375篇
  1976年   2336篇
  1975年   2828篇
  1974年   3119篇
  1973年   3085篇
  1972年   2746篇
  1971年   2607篇
  1970年   2215篇
  1969年   2159篇
  1968年   2031篇
  1967年   1799篇
排序方式: 共有10000条查询结果,搜索用时 6 毫秒
981.
A complex of immunological cell tests with M. pneumoniae antigen (the lymphocyte blast-cell transformation test, the allergic neutrophil alteration test) was carried out in order to establish the correlation between the results of positive seroconversion and the sepcific immunological reactivity of lymphoid cells in pneumonia patients. Mycoplasmic cutireactive allergen, when used for the accelerated diagnosis of mycoplasmic pneumonia in humans, was shown to be specific and safe. Cuti-allergic tests with mycoplasmic allergen allowed to diagnose mycoplasmic pneumonia at early stages (beginning from days 5--7), which ensures the possibility of indicating etiotropic treatment to patients in due time.  相似文献   
982.
983.
Experiments were conducted on mature female rats. Simultaneous administration through a tube for 14 days, daily, of mestranol (0.04 mg/kg) and megestrol acetate (0.8 mg/kg) gave no significant contraceptive effect, whereas the use of steroid preparations in the same doses in combination with antiadrenergic substances--dopegit (100 mg/kg) or pyrroxan (10 mg/kg) prevented pregnancy effectively.  相似文献   
984.
985.
986.
987.
The authors carried out a comparative analysis of the changes in the antibody synthesis and their immunological maturation in the immunization with various doses of the Vi-antigen of linear rats differing by the capacity to deposit this antigen. August rats with a high capacity to deposit the Vi-antigen (in comparison with Wistar rats in which this capacity was less) were characterized by an increased level of highly avid antibodies. The interlinear differences were found in the character of the changes in the antibody synthesis depending on the immunizing dose of the antigen. Genotypical peculiarities of the immunological maturation of the antibodies were demonstrated. The authors suppose that the described phenomenon was genetically determined and referred to the factors determining the individual immunological reactivity. In the choice of the optimal immunizing doses of the antigens the authors recommend complex determination of the antibody level and the degree of their avidity.  相似文献   
988.
A quantitative electron microscopical investigation of the sinus node of the atrioventricular His' bundle and of the perinodal working myocardium in intact rats and 7, 15 and 30 days after right-sided vagotomy has revealed variable character of changes in the neural elements of the zones mentioned. Certain ultrastructural rearrangements in the neural apparatus are described; they reflect a combination of destructive and regenerative processes in the heart under vagotomy. Thirty days after the operation, regeneration of the neural elements in the sinoauricular area is of restorative and in the atrioventricular area--of excess character. The data are presented on dynamics of changes in the diameter of the amyelinated neural fibers in the cardiac areas investigated. Participation of both nervi vagi in innervation of the main and additional pacemakers of the organ is discussed.  相似文献   
989.
990.
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