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   530159篇
  免费   27554篇
  国内免费   495篇
耳鼻咽喉   6681篇
儿科学   16945篇
妇产科学   12537篇
基础医学   92615篇
口腔科学   12347篇
临床医学   48501篇
内科学   95453篇
皮肤病学   11869篇
神经病学   34007篇
特种医学   19755篇
外国民族医学   53篇
外科学   78077篇
综合类   7610篇
现状与发展   2篇
一般理论   107篇
预防医学   38534篇
眼科学   11940篇
药学   41406篇
  1篇
中国医学   1126篇
肿瘤学   28642篇
  2021年   3892篇
  2018年   5731篇
  2017年   4126篇
  2016年   4869篇
  2015年   5360篇
  2014年   7114篇
  2013年   10498篇
  2012年   15574篇
  2011年   17389篇
  2010年   9955篇
  2009年   8821篇
  2008年   15710篇
  2007年   17443篇
  2006年   16939篇
  2005年   16259篇
  2004年   15880篇
  2003年   15261篇
  2002年   14782篇
  2001年   22428篇
  2000年   22971篇
  1999年   18919篇
  1998年   5232篇
  1997年   4364篇
  1996年   4397篇
  1995年   4124篇
  1992年   14414篇
  1991年   15823篇
  1990年   15952篇
  1989年   15632篇
  1988年   14309篇
  1987年   14200篇
  1986年   13168篇
  1985年   12690篇
  1984年   9401篇
  1983年   8001篇
  1982年   4178篇
  1979年   8945篇
  1978年   6387篇
  1977年   5151篇
  1976年   5507篇
  1975年   6616篇
  1974年   7421篇
  1973年   7166篇
  1972年   6603篇
  1971年   6313篇
  1970年   5888篇
  1969年   5469篇
  1968年   5163篇
  1967年   4622篇
  1966年   3963篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
962.
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   
963.
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   
964.
965.
966.
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   
967.
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   
968.
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   
969.
970.
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   
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