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   1410881篇
  免费   113542篇
  国内免费   3337篇
耳鼻咽喉   18361篇
儿科学   46549篇
妇产科学   41047篇
基础医学   200815篇
口腔科学   37692篇
临床医学   125995篇
内科学   284375篇
皮肤病学   33353篇
神经病学   116877篇
特种医学   53834篇
外国民族医学   464篇
外科学   210596篇
综合类   32755篇
现状与发展   3篇
一般理论   487篇
预防医学   109986篇
眼科学   31517篇
药学   98554篇
  1篇
中国医学   3349篇
肿瘤学   81150篇
  2021年   10848篇
  2019年   11669篇
  2018年   16576篇
  2017年   12674篇
  2016年   14260篇
  2015年   16002篇
  2014年   22551篇
  2013年   33389篇
  2012年   45380篇
  2011年   47926篇
  2010年   28161篇
  2009年   27045篇
  2008年   44320篇
  2007年   46830篇
  2006年   47403篇
  2005年   45867篇
  2004年   43761篇
  2003年   41699篇
  2002年   40202篇
  2001年   73007篇
  2000年   74560篇
  1999年   61564篇
  1998年   16991篇
  1997年   15431篇
  1996年   15585篇
  1995年   14791篇
  1994年   13396篇
  1993年   12583篇
  1992年   45845篇
  1991年   43491篇
  1990年   41500篇
  1989年   39566篇
  1988年   36195篇
  1987年   35355篇
  1986年   32863篇
  1985年   31279篇
  1984年   23825篇
  1983年   20023篇
  1982年   12210篇
  1981年   10783篇
  1979年   20703篇
  1978年   14578篇
  1977年   12087篇
  1976年   11368篇
  1975年   11621篇
  1974年   13991篇
  1973年   13533篇
  1972年   12636篇
  1971年   11472篇
  1970年   10913篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Nephrotoxic cysteine conjugates derived from a variety of halogenated alkenes are enzymatically activated via the beta-lyase pathway to yield reactive sulfur-containing metabolites which bind covalently to cellular macromolecules. Mitochondria contain beta-lyase enzymes and are primary targets for binding and toxicity. Previously, mitochondrial protein and/or DNA have been considered as molecular targets for cysteine conjugate metabolite binding. We now report that metabolites of nephrotoxic cysteine conjugates form covalent adducts with rat kidney mitochondrial phospholipids. Rat kidney mitochondria were incubated with the 35S-labeled conjugates S-(1,1,2,2-tetrafluoroethyl)-L-cysteine (TFEC), S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC), S-(1,2-dichlorovinyl)-L-cysteine, and S-(1,2,3,4,4-pentachlorobutadienyl)-L-cysteine. Quantitation of metabolite binding to whole mitochondria and to mitochondrial protein and lipid fractions revealed that as much as 42% of the 35S-label associated with the mitochondria was found in the lipid fraction. Total lipids were also extracted from 35S-treated mitochondria and separated by thin-layer chromatography. 35S-Containing metabolites were found in the lipid fractions from mitochondria treated with each of the conjugates. Lipids from both [35S]CTFC- and [35S]-TFEC-treated mitochondria contained major 35S-labeled lipid adducts which had similar mobility by thin-layer chromatography. Fatty acid analysis, 19F and 31P NMR spectroscopy, and mass spectrometric analyses confirmed that the major TFEC and CTFC adducts are thioamides of phosphatidylethanolamine.  相似文献   
92.
This paper examines the effect of patient age, tumour grade and extent of surgery on the outcome of treatment of 278 patients with high grade malignant gliomas referred to the Queensland Radium Institute between 1980 and 1987. The aim was to determine whether the extent of surgical resection alters survival rates. The extent of surgery had no effect on survival except for those patients with grade 3 tumours in whom a total excision was possible. Those in whom only a biopsy was done did not have a worse prognosis. Grading was found to be of importance, as patients with grade 3 tumours had a better survival than those with grade 4 tumours. In grade 4 tumours, those under 30 years of age had a better survival than those over 30 years, whereas with grade 3 tumours there was a gradation of age effect (under 40 years best, then 40–49 years, and those 50 years and over doing worst).  相似文献   
93.
94.
Fronto-ethmoidal mucocoeles: a histopathological analysis.   总被引:1,自引:0,他引:1  
From a series of 118 fronto-ethmoidal mucocoeles, 40 specimens have been submitted to detailed histological analysis. The frequency of each epithelial and sub-epithelial component is considered and reveals features which support a dynamic theory of bone resorption and formation rather than that of pressure erosion in the pathogenesis of mucocoeles.  相似文献   
95.
Analysis of accident logs in child day care centers indicates that biting is common, especially among toddlers 13 to 30 months of age. Children of this age often lack appropriate verbal skills and resort to aggressive means to achieve their goals. Still awkward in gross-motor skills, toddlers can also suffer self-bites following accidental falls. According to medical reports, human bites sometimes are more virulent than animal bites and can cause severe trauma. Although the AIDS virus has been cultured from saliva, transmission from saliva alone has not been documented. Bite injuries in day care, however, usually are minor and can be treated by washing, applying cold compresses, and comforting the child. Suggested methods to diminish the frequency of biting in day care include physical changes within the room, behavior modification, and other classroom management techniques.  相似文献   
96.
The Authors examine the correlation between hypertensive disorders of pregnancy and fetal growth. The results of a study of 342 pregnancies, confirm a significant correlation between hypertension and fetal growth retardation. These findings, so evident in moderate and severe hypertension, have also been confirmed in cases of mild hypertension. The medical treatment also in the pregnancies with mild hypertension, and a larger utilisation of operative deliveries, determined a decrease in perinatal mortality and morbidity.  相似文献   
97.
Fifteen cases of microtuboplasty were done as outpatient procedures at low cost and with increased patient convenience. Advances in outpatient surgery at free-standing surgery centers have allowed many new patient care innovations, and microsurgery should now be considered an outpatient procedure for gynecologic patients. Outpatient microtuboplastic surgery is not only feasible but perhaps preferable to that done as an inpatient procedure.  相似文献   
98.
99.
Background : The clinical course of chronic hepatitis B is variable. Patients with hepatic decompensation, bridging necrosis or an alpha-fetoprotein level greater than 100 ng/mL during an exacerbation of hepatitis have a high risk of developing cirrhosis. This study was conducted to evaluate the effect of colchicine in the prevention of cirrhosis in such patients.
Methods : Patients with risk factor(s) were randomized to receive either colchicine 5 mg/week or no specific treatment, the end point being development of cirrhosis.
Results : After a follow up period of 4 years, the treatment group had a marked reduction in exacerbations of acute hepatitis (32% vs. 63%/patient/year, P <0.005). Seven out of 38 patients in the treatment group and 10 out of 27 patients in the control group developed cirrhosis. The calculated cumulative incidence of cirrhosis by the end of first, second, third and fourth years in the treatment group was 8.7, 18.6, 32 and 32%, respectively. The corresponding figures in the control group were 30, 35.5, 46.3 and 73.2%, respectively, with a P -value of 0.057.
Conclusions : The results suggest that colchicine may prevent cirrhosis in chronic hepatitis B patients with risk factor(s), possibly by suppressing exacerbations of hepatitis through an anti-inflammatory effect.  相似文献   
100.
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