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   380410篇
  免费   24247篇
  国内免费   2811篇
耳鼻咽喉   5224篇
儿科学   8207篇
妇产科学   10105篇
基础医学   53289篇
口腔科学   11809篇
临床医学   30186篇
内科学   78653篇
皮肤病学   8575篇
神经病学   27266篇
特种医学   13942篇
外国民族医学   82篇
外科学   60760篇
综合类   9964篇
现状与发展   1篇
一般理论   64篇
预防医学   17489篇
眼科学   9454篇
药学   31139篇
  1篇
中国医学   2198篇
肿瘤学   29060篇
  2021年   2639篇
  2019年   2732篇
  2018年   4543篇
  2017年   3455篇
  2016年   3543篇
  2015年   4045篇
  2014年   5724篇
  2013年   7422篇
  2012年   10099篇
  2011年   10293篇
  2010年   6220篇
  2009年   5882篇
  2008年   9508篇
  2007年   10381篇
  2006年   10287篇
  2005年   9337篇
  2004年   8851篇
  2003年   8587篇
  2002年   8253篇
  2001年   28294篇
  2000年   28827篇
  1999年   23702篇
  1998年   5181篇
  1997年   4268篇
  1996年   3847篇
  1995年   3492篇
  1994年   3111篇
  1993年   2849篇
  1992年   16070篇
  1991年   14828篇
  1990年   14171篇
  1989年   13978篇
  1988年   12593篇
  1987年   12069篇
  1986年   11126篇
  1985年   10332篇
  1984年   6922篇
  1983年   5614篇
  1982年   2718篇
  1979年   5479篇
  1978年   3351篇
  1977年   2973篇
  1975年   2645篇
  1974年   3070篇
  1973年   2873篇
  1972年   2832篇
  1971年   2780篇
  1970年   2513篇
  1969年   2547篇
  1968年   2252篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Ganciclovir is a new antiviral compound (also called BW B759U, DHPG, BIOLF-62, and 2'NDG) that has been used for the treatment of cytomegalovirus (CMV) retinopathy in immunocompromised patients (bone marrow recipients or acquired immune deficiency syndrome [AIDS] victims). The authors studied the eyes of three AIDS patients with CMV retinopathy who died while receiving ganciclovir chemotherapy. Gross, microscopic, and ultrastructural studies of these cases showed varying degrees of retinal scarring and active CMV lesions at the margins of the scars. CMV antigens were localized in cells at all layers of retina at the border of the lesions and in isolated cells in a perivascular location within histologically normal appearing retina. These areas probably represent sites of recrudescence when the drug is discontinued. In situ hybridization using a cloned complementary DNA (cDNA) probe of human CMV corroborated the immunocytologic localization of the virus. Ultrastructural studies showed megalic syncytial cells containing mostly capsids exclusively in the cell nucleus. The cytoplasmic electron-dense membrane-bound bodies that have characterized untreated cases of CMV retinopathy were absent in the treated cases. An attempt to isolate CMV in tissue culture from the vitreous and retina of one of the cases yielded a negative result. Our results indicate that ganciclovir does not effectively eliminate CMV from the retina nor does it suppress expression of all viral genes. Ganciclovir appears to function by limiting viral DNA synthesis and subsequent packaging of viral DNA into infectious units, thereby acting as a virostatic chemotherapeutic agent.  相似文献   
992.
Using a new instrument designed by the Authors having two cannulas to allow filling of a contrast medium exclusively in the cervical canal and uterine cavity, selective hysterography was performed for 22 cases of endometrial carcinoma. This method was useful not only for evaluation of the size, location and growth patterns but also for estimation of the cervical involvement of endometrial carcinoma.  相似文献   
993.
Praziquantel (PQT) is a racemic mixture. Intragastric gavage of (-)-, (+)- and (+/-)-PQT 100 mg/kg were used to study the liver first pass effects in rabbits. HPLC was used to determine the concentration of each compound in the portal and systemic circulation, and in the bile within 4h. The results showed that all drugs were absorbed rapidly from the gut into the portal vein. The serum concentration in the portal vein were similar. However, over 90% of PQT and its enantiomers were extracted in the first passage through the liver. Intrinsic metabolic clearances of the liver of (-)-, (+)- and (+/-)-PQT were 50.3, 174.4 and 52.6 L/h, respectively. The serum concentrations of the three drugs markedly decreased in the systemic circulation, especially that of (+)-PQT. The AUC of (+)-PQT was apparently lower than that of (-)- or (+/-)-PQT. From these results, it is assumed that the first pass effects of PQT and its enantiomers in the liver are pronounced and most likely stereoselective. Also, unchanged PQT and its enantiomers were found in the bile of the rabbits.  相似文献   
994.
995.
A perusal of the medical literature re- vealod only one case of giant nonmetallic in traocular foreign body, 15x11x7 mm, removed in China However, no mention was made of the operative result of the wounded eye in the report. Usually after removal of intraocular foriegn bodies, especially the giant ones, the eyeball becomes inevitably atrophied, thus it has to be enucleated soon after operation. We removed a giant intraocular metallic foreign body, measuring 18.1x9x1.5 mm and weighing 0.24 g, from the left eye of a patient at our clinic. Follow-up l year after operation found that the eyeball of the affected eye was good in appearance with preservation of partial vision.  相似文献   
996.
997.
998.
The effect of a carbon dioxide (CO2) pneumoperitoneum and its duration on rabbit follicular oocytes was assessed by evaluating fertilization and subsequent embryonic development rates. CO2 may cross the plasma membrane and form carbonic acid, which liberates H+, thus lowering the intracellular pH. There were no significant differences in arterial pH and [HCO3-] between CO2 and air treatment groups, whereas arterial pCO2 and pO2 were significantly increased in the CO2 treatment group. We found that the duration of pneumoperitoneum, irrespective of type of gas used, was negatively correlated with success of embryonic development. These findings necessitate that more attention be given to the gas used for creation of a pneumoperitoneum during egg retrieval for in vitro fertilization and an attempt be made to minimize duration of the pneumoperitoneum.  相似文献   
999.
A 16 year old girl with post-streptococcal glomerulonephritis developed acute rheumatic fever 19 days afterwards. Previous publications on concurrent post-streptococcal glomerulonephritis and acute rheumatic fever are reviewed.  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