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   3351441篇
  免费   239390篇
  国内免费   7610篇
耳鼻咽喉   46041篇
儿科学   108515篇
妇产科学   90483篇
基础医学   488495篇
口腔科学   96232篇
临床医学   309761篇
内科学   643825篇
皮肤病学   72553篇
神经病学   270325篇
特种医学   122114篇
外国民族医学   827篇
外科学   487440篇
综合类   70834篇
现状与发展   13篇
一般理论   1281篇
预防医学   277829篇
眼科学   77260篇
药学   247682篇
  16篇
中国医学   7381篇
肿瘤学   179534篇
  2021年   29228篇
  2019年   29943篇
  2018年   41676篇
  2017年   31195篇
  2016年   33900篇
  2015年   38560篇
  2014年   53904篇
  2013年   81180篇
  2012年   112749篇
  2011年   119880篇
  2010年   70125篇
  2009年   64945篇
  2008年   109671篇
  2007年   116671篇
  2006年   116960篇
  2005年   113712篇
  2004年   108455篇
  2003年   103585篇
  2002年   98962篇
  2001年   144986篇
  2000年   148762篇
  1999年   125440篇
  1998年   37520篇
  1997年   32921篇
  1996年   32876篇
  1995年   31063篇
  1994年   28835篇
  1993年   27157篇
  1992年   98168篇
  1991年   96336篇
  1990年   93664篇
  1989年   89852篇
  1988年   82878篇
  1987年   81273篇
  1986年   76768篇
  1985年   73575篇
  1984年   55066篇
  1983年   47015篇
  1982年   28128篇
  1979年   50696篇
  1978年   36174篇
  1977年   29937篇
  1976年   28942篇
  1975年   30718篇
  1974年   37092篇
  1973年   35765篇
  1972年   33320篇
  1971年   31396篇
  1970年   29175篇
  1969年   27357篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The objective of this article is to describe histological methods currently used to study ovarian physiology that may have applicability to reproductive toxicology. Histologic techniques are, for the most part, inexpensive and easy to perform. Many of these techniques require little equipment and can be readily implemented in small laboratories. The resulting histological preparations are permanent, can be used over again for several different types of analyses, and provide objective, quantifiable endpoints. These techniques have been extremely useful for studying the ovary.  相似文献   
992.
K Rehse  U Lükens  G Claus 《Archiv der Pharmazie》1987,320(12):1233-1238
Platelet Aggregation Inhibiting and Anticoagulant Effects of Oligoamines, VII: Benzene-1,3,5-trialkanamines Seventeen title compounds were synthesized. Platelet aggregation induced by collagen in vitro is inhibited by 9 of them at IC50 = 2–4 μmol/L. Seven compounds depress the formation of fibrin to ≦ 25 % of normal in concentrations below 50 μmol/L. Compound 15 [4-(2-thienylbutyl)benzene-1,3,5-trimethanamine is the first oligoamine which shows anticoagulant and antiplatelet effects at the same concentration (25 μmol/L).  相似文献   
993.
994.
Clinical and biological data were evaluated using Desu univariate analyses or Cox multivariate analyses in a series of 1,777 chronic lymphocytic leukemia (CLL) patients from an Italian Cooperative Group. In univariate analyses, age and sex of patients, presence of bone marrow (BM; greater than or equal to 50%), and peripheral blood (PB; greater than or equal to 60,000/microL) lymphocytosis, anemia (hemoglobin [Hb] less than 11 g/dL), thrombocytopenia (less than 100,000/microL), direct Coombs' test positivity, hepatomegaly, splenomegaly, and extent of lymph node involvement were shown to be of significant prognostic value. Multivariate analyses, through a stepwise procedure, showed that the most important prognostic variables are Hb, hepatomegaly, lymph node involvement, PB lymphocytosis, and age and sex of patients. Further covariates would produce an improvement having a nonsignificant P value. Based on the results of multivariate analyses, a four-step staging using the significant variables of the Cox model is proposed.  相似文献   
995.
Synthesis of 2-(Hydrazinocarbonylthio)-acetic Acids and Cyclization to 3-Aminothiazolidine-2,4-diones N-mono- or N,N-disubstituted hydrazines are reacted with carbonyl sulfide, triethylamine and halogenoacetic acids to yield the 2-(hydrazinocarbonylthio) acetic acids 1 , which are cyclizised to yield the 3-aminothiazolidine-2,4-diones 2 by dicyclohexylcarbodiimide.  相似文献   
996.
Several reports in the literature suggest a relationship between lead intoxication and thermoregulatory capacity. To investigate the effects of lead on the control of body temperature, mice of the BALB/c strain were injected intraperitoneally with lead acetate (0 to 100 mg/kg) while colonic temperature was measured 30, 60, and 90 min post-injection at ambient temperatures (Ta) of 20 and 30 degrees C. Lead acetate caused a transient hypothermia, an effect which was augmented at cooler Ta's. In a second experiment, mice were injected with 100 mg/kg lead acetate and placed in a longitudinal temperature gradient to measure their preferred Ta. Lead acetate significantly reduced the preferred Ta during the first 30 min post-injection which augmented the lead-induced hypothermia. In a third experiment it was found that lead acetate-induced lethality was potentiated with increasing Ta. Hence, the hypothermic response to acute lead acetate treatment may be beneficial to survival.  相似文献   
997.
A case of Goldenhar’s Syndrome in a 10 year old girl is reported. The unusual features are the absence of epibulbar dermoid which is one of the major hallmarks of the Syndrome and the presence of an associated Cyanotic Heart disease.  相似文献   
998.
The Alaska mental health program is endowed with a 1-million-acre trust fund. A coalition of groups that make up the mental health constituency of the state united in a lawsuit to establish the trust. The history of this legacy, the struggle to realize its benefits, its current status, and some of its psychopolitical significance are discussed.  相似文献   
999.
1000.
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