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   2348753篇
  免费   181039篇
  国内免费   7741篇
耳鼻咽喉   31879篇
儿科学   77389篇
妇产科学   66424篇
基础医学   331731篇
口腔科学   65880篇
临床医学   207033篇
内科学   468571篇
皮肤病学   53465篇
神经病学   188928篇
特种医学   94311篇
外国民族医学   617篇
外科学   364916篇
综合类   52503篇
现状与发展   3篇
一般理论   683篇
预防医学   182763篇
眼科学   52421篇
药学   171543篇
  6篇
中国医学   4257篇
肿瘤学   122210篇
  2018年   22794篇
  2016年   20729篇
  2015年   23424篇
  2014年   32636篇
  2013年   49352篇
  2012年   63374篇
  2011年   67925篇
  2010年   41613篇
  2009年   40049篇
  2008年   64492篇
  2007年   69461篇
  2006年   70881篇
  2005年   69070篇
  2004年   66275篇
  2003年   64492篇
  2002年   62280篇
  2001年   108034篇
  2000年   111228篇
  1999年   93718篇
  1998年   27843篇
  1997年   24994篇
  1996年   25842篇
  1995年   25335篇
  1994年   23895篇
  1993年   22253篇
  1992年   77398篇
  1991年   75839篇
  1990年   73857篇
  1989年   70816篇
  1988年   66023篇
  1987年   64725篇
  1986年   61568篇
  1985年   59066篇
  1984年   44716篇
  1983年   38235篇
  1982年   23570篇
  1981年   21056篇
  1980年   19749篇
  1979年   41443篇
  1978年   29674篇
  1977年   25291篇
  1976年   23550篇
  1975年   25318篇
  1974年   29824篇
  1973年   28607篇
  1972年   26814篇
  1971年   24846篇
  1970年   22903篇
  1969年   21848篇
  1968年   20526篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
171.
Iron Fortification of Flours in Venezuela   总被引:1,自引:0,他引:1  
This paper reviews a conference about the impact of the iron fortification program in Venezuela; it was presented at the Pan American Health Organization regional technical meeting: "Iron Fortification: Where Are We in Terms of Iron Compounds," held in Washington January 10–12, 2001. Some of the data presented were published in the American Journal of Clinical Nutrition , including stimulating results about the impact of fortification of precooked corn and white wheat flours, as well as the prevalence of anemia and iron deficiency in the Venezuelan population. This article reports results from three surveys carried out in 1997, 1998, and 1999 on the same age and socioeconomic group that had been evaluated in 1990, 1992, and 1994. This article also shows the impact of iron fortification programs and the influence of other factors on the prevalence of iron deficiency and anemia during the last 7 years.  相似文献   
172.
173.
174.
Summary Experimental data suggest that multidrug resistance in cancer may be overcome by using an increased dose of anticancer agent(s) in combination with a resistance-modifying agent (RMA). We studied the pharmacokinetics and metabolism of both epirubicin (EPI) and verapamil (VPL) to explore the possible pharmacokinetic interactions between these two drugs. Ten patients with advanced breast cancer were given EPI (40 mg/m2 in a daily i.v. bolus for 3 consecutive days), and five of them also received VPL (4×120 mg/daily p.o. for 4 consecutive days). The data indicated a significant interaction between these two drugs that affected their metabolism. The areas under the concentration-time curves (AUC) obtained for epirubicin glucuronide, epirubicinol glucuronide, and both of the 7-deoxy-aglycones were higher in the EPI+VPL group as compared with the EPI group. The AUC, terminal half-life, mean residence time, volume of distribution at steady state, and plasma clearance of EPI alone as compared with EPI+VPL did not differ significantly. These results suggest either an induction of enzymes necessary for drug metabolism or an increase in the liver blood flow, resulting in an enhanced generation of metabolites with time or in an inhibition of excretion processes. Comparisons of the AUC values obtained for EPI and its metabolites after the first, second, and third injections of EPI revealed a cumulative effect for the metabolites that was more pronounced in the EPI+VPL group, being significant (P<0.05) for epirubicin glucuronide in both treatment groups and for epirubicinol glucuronide in the EPI+VPL group. Maximal concentrations of VPL and nor-VPL reached 705±473 and 308±122 ng/ml, respectively, with the steady-state concentrations being 265±42 ng/ml for VPL and 180±12 ng/ml for nor-VPL.This study was supported by the Erich und Gertrud Roggenbuck-Stiftung zur Förderung der Krebsforschung (Hamburg). The anthracycline metabolites were kindly provided by Dr. A. Suarato (Farmitalia, Milano, Italy); nor verapamil was provided by Dr. Traugott (Knoll, Ludwigshafen, Germany)  相似文献   
175.
The prevalence of heavy alcohol consumption is a major problem of increasing proportions throughout the world. Although alcohol sensitizing drugs and more recently serotonin uptake inhibitors are drug interventions with some following, their long term beneficial consequences have yet to be demonstrated. In recent years, we have demonstrated that manipulating activity in the renin-angiotensin system will dramatically alter voluntary alcohol consumption in rats. Based on these findings, the present study evaluated the ability of a class of drugs known as the angiotensin converting enzyme inhibitors to reduce voluntary alcohol drinking in laboratory animals. These drugs prevent the conversion of angiotensin I to angiotensin II. They have been licensed for use in Europe and North America and are indicated in the treatment of hypertension. Our experiments showed that both captopril (Capoten, Squibb) and enalapril (Vasotec, Merck Sharpe & Dohme) can reduce alcohol drinking in both normotensive and hypertensive animals regardless of whether the pattern of intake is in a bout or of a less exaggerated nature. Furthermore, this change in alcohol intake can occur without concomitant changes in blood pressure, plasma renin activity, overall fluid balance, or the distribution and metabolism of alcohol. Taken together these findings suggest that the angiotensin converting enzyme inhibitors should be evaluated in a clinical setting for they may prove to be a useful new treatment or treatment adjunct for alcohol abuse in humans.  相似文献   
176.
177.
178.
179.
Pulmonary valve insertion during reoperation for tetralogy of Fallot   总被引:1,自引:0,他引:1  
Our experience with pulmonary valve insertion during reoperation for residual lesions after initial open repair of tetralogy of Fallot in 15 patients is reported. Preoperatively, 14 patients were in moderate to severe congestive heart failure, and all 15 had decreased right ventricular (RV) function at cardiac catheterization. All 15 patients had pulmonary insufficiency but not as an isolated finding. The most common residual lesions encountered were ventricular septal defect in 9, tricuspid insufficiency in 11, and peripheral pulmonary arterial stenosis in 6. Tissue valves were inserted in all patients. Mean peak RV-left ventricular pressure ratio measured in the operating room decreased from 0.61 +/- 0.10 (+/- the standard deviation) to 0.47 +/- 0.17 (p less than 0.05). There were no operative deaths. At follow-up (mean, 33 months), all but 1 patient were in New York Heart Association Class I or II. Pulmonary valve insertion should be considered during reoperation for tetralogy of Fallot when pulmonary insufficiency and RV failure are present.  相似文献   
180.
APACHE II score and abdominal sepsis. A prospective study   总被引:7,自引:0,他引:7  
Therapeutic trials for intra-abdominal sepsis require pretreatment stratification; physiologic scoring has been recently proposed for this purpose. We have prospectively tested the validity of one such scoring system, namely, the Acute Physiology and Chronic Health Evaluation (APACHE II). As part of a larger database, we correlated APACHE II scores with mortality in 100 patients hospitalized for generalized peritonitis or abdominal abscess. Use of steroids was recorded because of our suspicion that steroids increase mortality but blunt the physiologic response to sepsis. Thirty-one patients died, including 12 of 19 patients receiving steroids. Stepwise discriminant analysis revealed that the APACHE II score and steroid use were each independently associated with the rate of mortality. We report a prospective validation of pretreatment APACHE II scoring in abdominal sepsis. Steroid use is an independent risk factor.  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