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   732844篇
  免费   28984篇
  国内免费   540篇
耳鼻咽喉   8180篇
儿科学   24191篇
妇产科学   16217篇
基础医学   113128篇
口腔科学   14093篇
临床医学   62543篇
内科学   132052篇
皮肤病学   12795篇
神经病学   52477篇
特种医学   29757篇
外国民族医学   53篇
外科学   113060篇
综合类   10427篇
现状与发展   2篇
一般理论   111篇
预防医学   58294篇
眼科学   14936篇
药学   51837篇
  1篇
中国医学   1766篇
肿瘤学   46448篇
  2021年   4176篇
  2019年   4065篇
  2018年   29017篇
  2017年   22867篇
  2016年   26978篇
  2015年   6540篇
  2014年   8170篇
  2013年   11625篇
  2012年   23143篇
  2011年   39845篇
  2010年   29568篇
  2009年   21481篇
  2008年   37784篇
  2007年   42996篇
  2006年   17864篇
  2005年   19297篇
  2004年   20651篇
  2003年   21876篇
  2002年   19029篇
  2001年   22987篇
  2000年   23822篇
  1999年   19284篇
  1998年   5585篇
  1997年   4767篇
  1996年   4627篇
  1995年   4355篇
  1992年   14619篇
  1991年   16040篇
  1990年   16178篇
  1989年   15815篇
  1988年   14466篇
  1987年   14369篇
  1986年   13295篇
  1985年   12818篇
  1984年   9497篇
  1983年   8081篇
  1982年   4293篇
  1979年   9058篇
  1978年   6466篇
  1977年   5175篇
  1976年   5584篇
  1975年   6627篇
  1974年   7465篇
  1973年   7174篇
  1972年   6606篇
  1971年   6325篇
  1970年   5929篇
  1969年   5526篇
  1968年   5199篇
  1967年   4635篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The authors describe 21 cases with resection of the retinal rupture valve with Nd:YAG laser impulse, performed to reduce the vitreoretinal tractions. Resection of the 'dump' rupture valve has been carried out in 10 cases, in the rest 11 the operation has been performed in the presence of a detachment of the retina. Anatomic success (detachment of the valve from the retina) has been achieved in 16 cases. The technique of the surgery is described, as are indications and contraindications to the operation.  相似文献   
992.
Sodium channel blocking activity was measured in a series of newly synthesized tertiary amine compounds and their quaternary derivatives applied externally on internally in the rat sensory neuron. The large difference in effectiveness of the quaternary compounds on external and or internal application became smaller and even disappeared with increasing lipophilicity of the compounds. No such difference was observed in the tertiary analogs. It was concluded that lipophilicity played an important role in determining the channel blocking activity of externally applied quaternary compounds. The results suggest that, in addition to the neutral form, highly lipophilic amine local anesthetics may penetrate into and/or pass across the neuronal membrane probably as electroneutral ion pair complexes consisting of the cationic form and an appropriate anion. The present results support our hypothesis which stresses, in addition to dissociability, the role of lipophilicity of amine local anesthetics in the pH dependence of their effect.  相似文献   
993.
994.
995.
It has been reported previously that populations with a decreased concentration of fecal bile acids have a lower incidence of colon cancer. We examined the importance of fecal bile acid dilution by wheat bran (WB) in inhibiting colonic tumorigenesis in an experimental animal model. Male F344 rats received oral doses of the colon carcinogen 1,2-dimethylhydrazine [CAS: 540-73-8] and were assigned randomly to groups fed one of four semipurified diets for 26 weeks. The diets were fiber-free (FF), 10% WB, FF + bile salts, or WB + bile salts. The amount of bile salts added was adjusted to produce a fecal bile acid concentration in the group fed WB + bile salts equal to that found in the FF groups. Fecal bile acid concentrations at 12 and 24 weeks in the WB + bile salts group were similar to those in the FF group. Gross and microscopic findings at necropsy revealed a reduced total number and multiplicity of colon tumors in both bran-fed groups. Although the fecal bile acid concentrations of the FF and WB + bile salts groups were equal, the latter showed a significant reduction in tumor yield.  相似文献   
996.
Chlamydia trachomatis recently has emerged as the most frequently diagnosed sexually transmitted disease (STD) agent. An estimated three million cases are diagnosed annually in the United States. Because the infection is not reportable, only estimates can be made. The most common STD, it also is often transmitted to infants through infected mothers. Prevention and treatment of the disease in newborns require different procedures from those for gonorrhea, as do diagnostic and treatment methods for infected adults. Chlamydia also appears to pose a threat to pregnancy.  相似文献   
997.
Twenty patients (15 males; five females) aged 11-70 years, with urinary tract infections were treated with one 250 mg tablet of ciprofloxacin every 12 h for 5-10 days. Clinical response to this treatment was the complete disappearance of symptoms in 85% of cases and the elimination of the micro-organism responsible for infection. In only three patients, who all had urinary calculus in addition to an infection, clinical failure of the therapy occurred and the causative micro-organism persisted. Tolerance to the therapy was excellent in this study, no adverse reactions connected with the treatment being reported.  相似文献   
998.
999.
External enhancement of free-radical processes followed by considerable tissue accumulation of toxic lipid peroxidation products in an early postresuscitation period is the main pathochemical mechanism which causes lung air-blood barrier disturbance. The basis of animal respiratory insufficiency morphogenesis after clinical death is ventilation failure (dis- and atelectasis), circulation disorder (edema, hemorrhage) being secondary. However, morphological examination of lungs of animals after four-minutes clinical death from an acute blood loss and resuscitation showed that it is the severity of circulation disorders that determines the animals condition in the postresuscitation period.  相似文献   
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