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   10975篇
  免费   1418篇
  国内免费   88篇
耳鼻咽喉   44篇
儿科学   114篇
妇产科学   216篇
基础医学   911篇
口腔科学   77篇
临床医学   760篇
内科学   1341篇
皮肤病学   99篇
神经病学   244篇
特种医学   291篇
外国民族医学   1篇
外科学   658篇
综合类   230篇
现状与发展   2篇
预防医学   2242篇
眼科学   26篇
药学   656篇
  2篇
中国医学   47篇
肿瘤学   4520篇
  2024年   24篇
  2023年   554篇
  2022年   639篇
  2021年   704篇
  2020年   826篇
  2019年   608篇
  2018年   595篇
  2017年   629篇
  2016年   621篇
  2015年   731篇
  2014年   999篇
  2013年   810篇
  2012年   467篇
  2011年   371篇
  2010年   522篇
  2009年   516篇
  2008年   290篇
  2007年   321篇
  2006年   281篇
  2005年   251篇
  2004年   193篇
  2003年   211篇
  2002年   197篇
  2001年   209篇
  2000年   159篇
  1999年   169篇
  1998年   105篇
  1997年   75篇
  1996年   78篇
  1995年   55篇
  1994年   36篇
  1993年   24篇
  1992年   45篇
  1991年   49篇
  1990年   38篇
  1989年   35篇
  1988年   26篇
  1987年   4篇
  1986年   1篇
  1985年   4篇
  1984年   3篇
  1981年   1篇
  1980年   4篇
  1954年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Estrogenic hormones play critical roles in many aspects of women's health. Therefore, the impact of any hormonal manipulation must be carefully considered. While the evidence is good that chemoprevention, or more accurately chemosuppression, of breast cancer with tamoxifen is possible, further data are needed to support the case that hormone replacement with tamoxifen in healthy postmenopausal women would provide overall health benefits. Specifically, further data are needed regarding the biological effects of tamoxifen on risk factors for cardiovascular disease, on bone, on the liver, on the uterus, and on the coagulation system. Frequency, severity, and predictors for vasomotor, gynecologic, and depressant side effects also need to be well described. These data will allow rigorous cost-effectiveness analysis of hormone replacement therapies with tamoxifen and estrogen, as well as an analysis of the cost effectiveness of a clinical trial to prove definitively critical health benefits.  相似文献   
62.
63.
64.
There is evidence that long-term maintenance of a low-fat diet reduces preference for high-fat foods. Sensory evaluation of the taste of fat, and preference for high and low-fat foods were studied in a group of former participants in a randomized dietary intervention trial aimed at lowering fat consumption. Intervention subjects consuming less than 25% of daily calories as fat and control subjects consuming more than 35% of daily calories as fat agreed to be in a "taste perception" study. In Study 1, subjects tasted 20 dairy solutions containing different levels of fat and sugar. Subjects rated the perceived intensity of fat taste, and of liking, for each of the solutions. In Study 2, subjects were asked to taste and rate 4 high-fat and 4 low-fat snack foods, and were then allowed to freely consume these foods in a preference test. Intervention and control subjects were similar in their sensory evaluation of the taste of fat in Study 1. In Study 2, intervention subjects reported a reduced hedonic rating of the taste of high-fat snack foods compared to control subjects, yet intervention subjects consumed the same amount of high-fat snack foods as control subjects. We conclude that a successful outcome in a dietary intervention may be due to social and cognitive factors, in addition to potential changes in hedonic response to fat.  相似文献   
65.
The accuracy of historical information derived from self-administered questionnaires must be confirmed. We report the results of studies conducted to assess the reliability and validity of data collected from a comprehensive cancer risk factor questionnaire developed at The University of Texas M.D. Anderson Cancer Center. A comparison of the basic demographic data of a randomly selected sample of 80 respondents and 70 nonrespondents revealed no fundamental ethnic or socioeconomic differences. We verified self-reported past illnesses, surgical procedures, and cancers by reviewing 72 patient charts, using stringent diagnostic criteria for verification. We noted substantial agreement between self-reported and documented illnesses and operations. With the exception of nine patients who misclassified metastatic disease, the verification of primary cancers was excellent. We determined reliability by interviewing 50 of these patients by telephone. Questions with a dichotomous outcome (e.g., smoking status) were reliably answered; however, those requiring quantification (e.g., amount of alcohol consumed) were less accurately reported on interview. While we recognize the limitations of self-administered questionnaires, we believe this program will develop into a comprehensive, standardized, easily accessible patient risk factor data base.  相似文献   
66.
67.
《Pancreatology》2007,7(5-6):514-525
Background and Aims: Approximately 10% of pancreatic adenocarcinoma is familial. Approximately 50% of Ist-degree relatives (FDRs) have endoscopic ultrasound (EUS) findings of chronic pancreatitis. We modeled the natural history of these patients to compare 4 management strategies. Methods: We performed a systematic review, and created a Markov model for 45-year-old male FDRs, with findings of chronic pancreatitis on screening EUS. We compared 4 strategies: doing nothing, prophylactic total pancreatectomy (PTP), annual surveillance by EUS, and annual surveillance with EUS and fine needle aspiration (EUS/FNA). Outcomes incorporated mortality, quality of life, procedural complications, and costs. Results: In the Do Nothing strategy, the lifetime risk of cancer was 20%. Doing nothing provided the greatest remaining years of life, the lowest cost, and the greatest remaining quality-adjusted life years (QALYs). PTP provided the fewest remaining years of life, and the fewest remaining QALYs. Screening with EUS provided nearly identical results to PTP, and screening with EUS/FNA provided intermediate results between PTP and doing nothing. PTP provided the longest life expectancy if the lifetime risk of pancreatic cancer was at least 46%, and provided the most QALYs if the risk was at least 68%. Conclusions: FDRs from familial pancreatic cancer kindreds, who have EUS findings of chronic pancreatitis, have increased risk for cancer, but their precise risk is unknown. Without the ability to further quantify that risk, the most effective strategy is to do nothing.  相似文献   
68.
69.
70.
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