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   9098篇
  免费   586篇
  国内免费   24篇
耳鼻咽喉   51篇
儿科学   276篇
妇产科学   237篇
基础医学   1014篇
口腔科学   414篇
临床医学   968篇
内科学   1729篇
皮肤病学   86篇
神经病学   827篇
特种医学   494篇
外科学   1260篇
综合类   378篇
一般理论   11篇
预防医学   946篇
眼科学   176篇
药学   463篇
  2篇
中国医学   3篇
肿瘤学   373篇
  2021年   130篇
  2020年   61篇
  2019年   117篇
  2018年   129篇
  2017年   108篇
  2016年   110篇
  2015年   131篇
  2014年   171篇
  2013年   287篇
  2012年   410篇
  2011年   429篇
  2010年   236篇
  2009年   211篇
  2008年   373篇
  2007年   420篇
  2006年   393篇
  2005年   385篇
  2004年   368篇
  2003年   333篇
  2002年   347篇
  2001年   278篇
  2000年   284篇
  1999年   262篇
  1998年   117篇
  1997年   107篇
  1996年   99篇
  1995年   84篇
  1994年   93篇
  1993年   88篇
  1992年   224篇
  1991年   220篇
  1990年   237篇
  1989年   215篇
  1988年   219篇
  1987年   231篇
  1986年   198篇
  1985年   215篇
  1984年   107篇
  1983年   106篇
  1982年   72篇
  1981年   72篇
  1980年   66篇
  1979年   86篇
  1978年   82篇
  1977年   65篇
  1976年   55篇
  1974年   59篇
  1972年   59篇
  1971年   65篇
  1970年   49篇
排序方式: 共有9708条查询结果,搜索用时 0 毫秒
21.
A review of the life and achievements of Kenneth Fitzpatrick Russell, whose death in his 76th year robbed us of a civilized gentleman who was at the zenith of his creative output, would be a daunting task, if only because of the breadth of his hobbies and interests: art and medical literature; reading; sinology and seal carving; numismatics, medical philately; bookbinding, collecting bookplates; carpentry; metal work, including pewter casting and silversmithing; model ship building and cooking. Yet these various interests were simply a backdrop to his public career at the University of Melbourne and the Royal Australasian College of Surgeons, where he laid the foundations of an international reputation as scholar and collector.  相似文献   
22.
1. Evidence that vegetarian dietary patterns lower blood pressure (BP) comes from both population studies and randomized controlled trials in normotensive and hypertensive subjects. 2. The effect has been shown most clearly in those who keep to a strict lacto-ovo vegetarian diet characterized by a relatively low intake of saturated fat, a high polyunsaturated/saturated fat ratio, and a high intake of fruit, vegetables and other fibre containing products. Randomized controlled dietary trials suggest the effects are independent of dietary sodium, additive to that of calorie restriction, and not due to the absence of meat protein per se. Indeed, recent population studies suggest an inverse relationship between dietary protein and BP. 4. Dietary fats, fibre, potassium, magnesium and calcium do not independently seem to account for the effects. A possible role for complex carbohydrate in conjunction with the other dietary factors has yet to be fully explored.  相似文献   
23.
The overall consensus of the Work Group was that the workshop provided an excellent opportunity for discussion of the scientific issues pertaining to non-occupational exposures to gasoline as it related to public health officials, legal and regulatory agencies, and industrial (workplace) concerns. It was enlightening to discuss the implications of new and existing data and methods for determining the public's exposure to gasoline. The workshop resulted in a list of data needs and a vision of the future research that will be required to aid future users of exposure data.  相似文献   
24.
Of 86 patients with inoperable malignant dysphagia, 68 (79 per cent) underwent successful palliation by endoscopic laser therapy, of whom 24 remained well palliated until the time of death. In 18 patients laser treatment was unsuccessful and nine of these underwent intubation, eight successfully. After successful laser therapy, dysphagia recurred in 44 patients a mean of 7.8 weeks later. Of these, 31 received palliation until death by dilatation with or without laser therapy, and 13 required intubation. The overall laser-related complication rate was 12 per cent with a mortality rate of 4 per cent. The intubation-related mortality rate was 9 per cent.  相似文献   
25.
This paper presents some of the findings from the Smoking in Pregnancy study of attitudes towards smoking among pregnant women, mothers of young children and their partners in East Surrey. As part of the study, respondents completed a General Health Questionnaire to identify mental health difficulties and, if they were smoking at the time of the study, they also completed the Fagerstrom nicotine addiction test. Eleven female respondents had high scores on the General Health Questionnaire, suggesting symptoms of depression, anxiety and/or social dysfunction for these women. There was no evidence that smokers were suffering from greater mental health difficulties than ex-smokers or non-smokers. However, the General Health Questionnaire scores of smokers were positively associated with their level of nicotine dependence. Furthermore, when General Health Questionnaire scores of all respondents were compared with self-reported health status there was a marked discrepancy suggesting under-reporting of symptoms by women.  相似文献   
26.
A cross-over design study was used to examine the metabolic consequences of enteral feeding for 48 to 96 hours with either a branched-chain amino acid (BCAA)-enriched (44% BCAA) or a conventional egg protein formulation in 12 severely burned adult patients. A stable isotope labeled leucine (L-1-13C-leucine) tracer approach was used to measure leucine flux and oxidation and to estimate rates of whole body protein synthesis and breakdown. Additionally, 15N2-urea and 6,6-2H-glucose were administered to assess the status of urea and glucose kinetics with these two nutritional treatments. Average patient age was 54 years, and average burn surface area was 36%. Studies were conducted at an average of 25 days postburn. Leucine flux and oxidation were significantly (p less than 0.01, by paired t-test) elevated with BCAA feeding as compared to the egg protein formulation. However, there were no significant differences in the rates of leucine incorporation into, or release from, proteins (p greater than 0.05) between the two dietary periods. Mean rates of body protein synthesis and breakdown for each diet were about twice the rates reported for healthy young adults. Apparent nitrogen balance measurements were not statistically different (p greater than 0.1) between the two diet periods. Furthermore, urea and glucose kinetics failed to show significant differences between the two diet periods. It appears from these results that the major consequences of increased intake of leucine from the BCAA formula is an enhanced rate of leucine oxidation. In conclusion, (1) the availability of BCAAs is not rate-limiting for enhanced protein synthesis in burn patients, and (2) the use of enriched BCAA formulas in burn therapy does not appear to offer advantages over a routinely used enteral egg protein formula, at least based on the present determinations.  相似文献   
27.
Prospective studies suggest that tea may protect against cardiovascular disease. A potential mechanism for such an effect involves inhibition of lipid peroxidation by polyphenolic antioxidants derived from tea. Our objective was to determine whether regular ingestion of tea could inhibit in vivo lipid peroxidation. Two controlled intervention studies assessed the effects of regular ingestion of tea on lipid peroxidation determined by measurement of urinary F(2)-isoprostane excretion. Study 1: The effects of 1000 mL/d of green tea and black tea were compared with hot water containing caffeine in 13 subjects with elevated blood pressure using a randomized 3-period (7 d each) crossover design. Study 2: The effects of 1250 mL/d of black tea were compared with hot water in 22 subjects with mildly raised serum total cholesterol concentrations using a randomized 2-period (4 wk each) crossover design. F(2)-isoprostane excretion was not altered after regular ingestion of green tea (273 +/- 48 pmol/mmol creatinine) or black tea (274 +/- 39 pmol/mmol creatinine) in comparison with hot water (263 +/- 47 pmol/mmol creatinine; Study 1), or by regular ingestion of black tea (334 +/- 71 pmol/mmol creatinine) in comparison with hot water (355 +/- 75 pmol/mmol creatinine; Study 2). These results do not support the suggestion that polyphenolic antioxidants derived from tea inhibit in vivo lipid peroxidation.  相似文献   
28.
29.
30.
Objectives:  The goal of this retrospective study was to examine factors differentiating persons with bipolar disorder who did or did not have comorbid lifetime substance use disorders (SUD) at an index assessment. We also explored the chronology of onset of mood and SUD.
Methods:  We studied 146 subjects with DSM-defined bipolar disorder. Subgroups with and without lifetime SUD were compared on demographic and clinical measures.
Results:  Substance abuse disorders in this bipolar sample were associated with male sex, impulsive-aggressive traits, comorbid conduct and Cluster B personality disorders, number of suicide attempts and earlier age at onset of a first mood episode. In a multivariable logistic regression analysis, male sex and aggression and possibly earlier age at mood disorder onset were associated with SUD. In those with or without SUD, the first mood episode tended to be depressive and to precede the onset of SUD.
Conclusions:  In persons with bipolar disorder, an earlier age of onset and aggressive traits appear to be factors associated with later development of comorbid SUD.  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