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   514044篇
  免费   33255篇
  国内免费   614篇
耳鼻咽喉   6893篇
儿科学   16838篇
妇产科学   13521篇
基础医学   85009篇
口腔科学   14473篇
临床医学   44338篇
内科学   93604篇
皮肤病学   12154篇
神经病学   36181篇
特种医学   18453篇
外国民族医学   63篇
外科学   77035篇
综合类   8471篇
一般理论   118篇
预防医学   38966篇
眼科学   12134篇
药学   40541篇
中国医学   1006篇
肿瘤学   28115篇
  2018年   4930篇
  2015年   4508篇
  2014年   6059篇
  2013年   9544篇
  2012年   12866篇
  2011年   14268篇
  2010年   8299篇
  2009年   7770篇
  2008年   13692篇
  2007年   14696篇
  2006年   14938篇
  2005年   14353篇
  2004年   14045篇
  2003年   13387篇
  2002年   13268篇
  2001年   24067篇
  2000年   25078篇
  1999年   20555篇
  1998年   5426篇
  1997年   4705篇
  1996年   5041篇
  1995年   4625篇
  1994年   4318篇
  1993年   4135篇
  1992年   15725篇
  1991年   16309篇
  1990年   16422篇
  1989年   15796篇
  1988年   14575篇
  1987年   14419篇
  1986年   13597篇
  1985年   12975篇
  1984年   9627篇
  1983年   8247篇
  1982年   4559篇
  1981年   4229篇
  1979年   9418篇
  1978年   6855篇
  1977年   5772篇
  1976年   5602篇
  1975年   6396篇
  1974年   7634篇
  1973年   7130篇
  1972年   6960篇
  1971年   6685篇
  1970年   6172篇
  1969年   5888篇
  1968年   5559篇
  1967年   5012篇
  1966年   4450篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
991.
992.
Multidrug resistance in human renal cell carcinoma is mainly caused by expression of the MDR1 gene and is characterized by a broad spectrum cross resistance to many natural product chemotherapeutic agents. This resistance can be overcome by applying chemosensitizers which inhibit the function of the MDR1 gene product P-glycoprotein. The development of new reversing agents with fewer side effects and a higher potency in modifying resistance is a high priority of research on drug resistance. We have evaluated four new verapamil derivatives on 21 primary human renal cell carcinomas in vitro, and also tested them in an MDR-transgenic mice model. These mice express the human MDR1 gene in their bone marrow cells and measurement of their white blood counts provides a simple, rapid and reliable system to screen for the potency of MDR-reversing agents in vivo. We demonstrate here that all four drugs are effective in reversing multidrug resistance in primary cultures of human renal cell carcinomas when used in combination with vinblastine chemotherapy, and to a lesser extent with doxorubicin or daunomycin chemotherapy. Our in vivo data indicate that two of these reversing agents display low toxicity at high concentrations and are more effective at low, clinically achievable concentrations, than the other two drugs and R-verapamil. These results make the two new drugs attractive candidates to be taken into clinical trials.  相似文献   
993.
994.
995.
996.
Furfuryl amine salt of 4-chloro-N-(2-furylmethyl)-5-sulfamoyl anthranilic acid was shown to exert more pronounced diuretic and saluretic action in rats, mice and dogs than that of furosemide. The previous administration of furfuryl amine salt of furosemide promoted normalization of the excretory processes of the kidney and increased survival rate of rats in ischemia of the single kidney. The antiedema activity of the drug was found to be much more pronounced than that of furosemide.  相似文献   
997.
998.
OBJECTIVE: Inpatients with major depressive illness often have coexistent nonaffective psychiatric and/or medical conditions. The authors' objective is to address the following questions: 1) What is the effect of comorbid illness on the severity of major depression and associated psychosocial factors? 2) How does the course of depression differ for patients with and without concurrent illness? 3) Do patients with compound depression differ in rate of recovery and time to recovery from patients with pure depression? METHOD: The subjects were 78 patients with a DSM-III diagnosis of major depression who were consecutively admitted to an acute care university-affiliated psychiatric hospital; 37 of these patients had major depression only and 41 had major depression compounded by a coexisting axis I, II, or III condition. The patients were studied while hospitalized and for 12 months after hospital discharge. Instruments used included the Modified Hamilton Rating Scale for Depression, the Global Assessment Scale, and the Social Readjustment Rating Scale. RESULTS: Patients with compound depression reported significantly poorer functioning over the 12-month follow-up period and had lower recovery rates than the patients with pure depression. There were no differences in recovery rates between men and women with compound depression, but significantly more men than women with pure depression recovered. CONCLUSIONS: Compound depression is a common clinical occurrence, the course of illness is more difficult for patients with compound depression than for patients with pure depression, and the recovery rate of patients with compound depression is lower than that of patients with pure depression.  相似文献   
999.
Distribution of thymic tissue in the mediastinal adipose tissue.   总被引:5,自引:0,他引:5  
The distribution of thymic tissue in the anterior mediastinal, retrocarinal, and preaortic fat was examined histologically in 27 autopsy subjects. Thymic tissue was found in the anterior mediastinal fat in 12 subjects (44.4%), in the retrocarinal fat in two (7.4%), and in the preaortic fat in none. The finding of ectopic thymic tissue in these areas has not been reported previously, would appear to be surgically inaccessible via a median sternotomy, and may be responsible in part for some of the failures of thymectomy in the treatment of myasthenia gravis.  相似文献   
1000.
A survey of endoscopy units in the West Midlands, UK, was undertaken to ascertain the management of colonic perforation during colonoscopy. Fifteen perforations were reported from a total of 17,500 colonoscopies performed in 14 units (a rate of 0.09 per cent). In seven patients the diagnosis was suspected or diagnosed immediately and in the remaining eight 2-72 h later. Four patients with associated pathology (carcinoma, Crohn's disease, ulcerative colitis and a polyp) had resection and primary anastomosis. Seven patients had a simple oversew, four of these having had a delayed diagnosis. In four cases the site of perforation was not identified, but only one patient had conservative treatment. Three patients had drainage and a defunctioning colostomy. There was no significant morbidity following treatment. It is recommended that patients who have had a good bowel preparation should be treated conservatively unless there is a large perforation or an underlying carcinoma.  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