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   11470篇
  免费   1033篇
  国内免费   50篇
耳鼻咽喉   134篇
儿科学   449篇
妇产科学   224篇
基础医学   1710篇
口腔科学   284篇
临床医学   1459篇
内科学   2499篇
皮肤病学   194篇
神经病学   1068篇
特种医学   544篇
外国民族医学   2篇
外科学   1332篇
综合类   282篇
一般理论   7篇
预防医学   940篇
眼科学   130篇
药学   678篇
中国医学   7篇
肿瘤学   610篇
  2021年   105篇
  2019年   104篇
  2018年   151篇
  2017年   137篇
  2016年   155篇
  2015年   157篇
  2014年   214篇
  2013年   369篇
  2012年   419篇
  2011年   402篇
  2010年   280篇
  2009年   267篇
  2008年   413篇
  2007年   473篇
  2006年   458篇
  2005年   411篇
  2004年   396篇
  2003年   394篇
  2002年   375篇
  2001年   377篇
  2000年   371篇
  1999年   335篇
  1998年   192篇
  1997年   191篇
  1996年   217篇
  1995年   161篇
  1994年   143篇
  1993年   159篇
  1992年   268篇
  1991年   245篇
  1990年   258篇
  1989年   278篇
  1988年   272篇
  1987年   265篇
  1986年   206篇
  1985年   209篇
  1984年   183篇
  1983年   129篇
  1982年   98篇
  1981年   129篇
  1980年   120篇
  1979年   141篇
  1978年   115篇
  1977年   131篇
  1976年   124篇
  1975年   121篇
  1974年   95篇
  1972年   94篇
  1969年   88篇
  1960年   79篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
In conclusion, at present, no consistent endocrine abnormalities can be detected in patients suffering from Alzheimer's disease. However, assessment of neuroendocrine function might help identify subpopulations of patients with particular neurotransmission abnormalities who are likely to benefit from a specific pharmacologic strategy. For example, patients in whom cholinomimetic drugs produce the greatest elevation in plasma cortisol concentration appear to derive the most symptomatic benefit from these drugs.  相似文献   
32.
The effect of acute and sequential volaemic changes on the gastroduodenal flow of saline was assessed in 23 anaesthetized dogs following two different experimental protocols. Hypervolaemia, by i. v. infusion of saline, induced a gradual decrease on gastroduodenal flow which amounted to 76% below control values (P < 0.001) when volaemic expansion attained 5% of body weight. This effect was volume dependent (17% increase on gastroduodenal flow per volume of infused saline equivalent to 0.5% of body weight, P < 0.001), lasted for at least 90 minutes after infusion was completed and was also obtained by expanding previously bled animals. Hypovolaemia due to bleeding was followed by an increase on gastroduodenal flow of about 88% above control values (P < 0.05) when haemorrhage was equal to 3% of body weight. This effect was also volume dependent (23 % increase on gastroduodenal flow per volume of blood shed equivalent to a 0.5% of body weight, P < 0.01) and was reversed after blood volume was restored. These modifications in the resistance of the gastroduodenal segment to the flow of liquid due to acute volaemic changes suggest that the extracellular fluid volume modulates the contractile activity of the gastroduodenal portion of the gut possibly to set a gastroduodenal handling of liquid adequate to cope with volaemic imbalances.  相似文献   
33.
34.
The Liverpool Continuing Health in the Community Study has followed up 1070 elderly community subjects over 6 years. In the first year 123 subjects had case-level depression. Three years later 49 (39.8%) of the previously depressed were recovered, 33 (26.8%) were depressed, 16 (13%) were not available for interview and 25 (20.3%) were dead. This study looks at factors associated with the 3-year outcome of patients who were depressed at year 0. Two outcome groups that were compared were a recovered depression group and a recurrent/persistent depression group. The factors that were significantly associated with a recurrence of depression (or persistent depression) at year 3 were bereavement of a close figure in the 6 months before interview, loneliness and life dissatisfaction at year 3. A variety of traditional risk factors for depression (including age, marital status, physical ill-health and incapacity) failed to attain significance in predicting recurrent or persistent depression. When combined, both recovered and recurrently depressed groups at year 3 had significantly higher levels of pain and a higher number of serious upsets in the past 6 months and 6 weeks compared to a compared to a control group. The depressed at year 0 were more likely to have entered more dependent forms of accommodation by year 3.  相似文献   
35.
36.
A recent survey of antibiotic prophylaxis found that local practice often differed from that recommended by authoritative bodies such as the British Society for Antimicrobial Chemotherapy (BSAC) and the American Heart Association (AHA). Practitioners found the subject confusing and requested guidance. For these reasons we present current recommendations. Unfortunately all recommendations are based on animal studies and an understanding of the pathogenesis of bacterial endocarditis in humans. There are no controlled trials in humans on which to base guidelines, so rigidity is inappropriate. It is also important to realise that optimal prophylaxis will not eliminate bacterial endocarditis. In developed countries it has been estimated that only 10% of cases of endocarditis are theoretically preventable.  相似文献   
37.
Head trauma was induced in rats by a weight-drop device, falling over the exposed skull over the left hemisphere. The neurological state of the rats was evaluated by a neurological severity score at 1 h and 18 h post head trauma. At 18 h post head trauma, rats were decapitated and tissue from the vicinity of the injury and from a corresponding area in the contralateral hemisphere was taken for specific gravity (SG) determination using linear gradient columns. Slices were taken from the same sites for incubation in Krebs-Ringer solution, and the concentrations of prostaglandin (PG)E2, 6-keto-PGF1 alpha, and thromboxane B2 accumulated in the medium during 1 h were measured by radioimmunoassay. In one experimental group, rats were pretreated with intraperitoneal dexamethasone sodium phosphate (4 mg/kg) 18 and 2 h before head trauma, and a third dose was given 8 h post head trauma. Another group was treated with intraperitoneal indomethacin (10 mg/kg) 1 h before and 7 h after head trauma. Other groups were treated immediately and 8 h after head trauma with 4, 8, 15, or 30 mg/kg of dexamethasone sodium phosphate. Another group of rats was treated with free dexamethasone (10 mg/kg) right after head trauma and 8 h later. Head trauma induced edema, as expressed by decreased SG, in the left hemisphere of all traumatized rats. Neither treatment protocol affected the neurological severity score of the injured rats or the SG of the contused hemisphere. PG synthesis, on the other hand, was significantly reduced following indomethacin or free dexamethasone, both in sham and traumatized rats, but not in dexamethasone sodium phosphate-treated rats. We conclude that pretreatment with indomethacin, dexamethasone sodium phosphate, or dexamethasone, used in the present protocols, does not affect posttraumatic cerebral edema. Thus, the role of PGs as mediators of edema formation remains unclear.  相似文献   
38.
39.
Summary.  Although several authoritative, evidence-based, guidelines for the prevention of venous thromboembolism (VTE) have been published, the use of VTE prophylaxis in routine clinical practice varies markedly. Even in orthopedic surgery, the indication for which prophylaxis is used most often, a significant proportion of surgeons do not use routine prophylaxis. When prophylaxis is used, guideline recommendations are often not followed. A number of factors may contribute to the under-use of guidelines. Physician-related factors include: a lack of awareness of, or familiarity with, the guidelines; a perception that VTE is not a significant problem or that VTE prophylaxis is ineffective; and concern about potential bleeding risks. The guidelines may also be perceived to be too complicated or difficult to apply in a routine manner. In addition, a lack of facilities or resources may also present a barrier to implementation of the guidelines. A number of strategies are being investigated in an attempt to improve compliance with guidelines for VTE prophylaxis. For example, the Investigators Against Thromboembolism (INATE) initiative has developed a simplified pocket guideline on VTE prophylaxis in orthopedic and trauma surgery in order to raise awareness of the current guideline recommendations.  相似文献   
40.
OBJECTIVE: Limited work has addressed the construct validity of the Cohen-Mansfield Agitation Inventory (CMAI) in nursing home patients. The authors tested the CMAI factor structure by use of data from three samples of nursing home patients categorized a priori as having at least mild behavioral and psychological symptoms of dementia. METHODS: CMAI data were from the baseline assessment of three randomized, placebo-controlled trials of risperidone for treating elderly nursing home patients. Exploratory factor analyses were conducted on two trials (N = 304; N = 344), and the results of these exploratory factor analyses were then tested with confirmatory factor analysis by use of data from a third trial (N = 617). RESULTS: Principal-components analysis suggested the presence of four factors: 1) Aggressive Behavior (hitting, kicking, scratching, biting, pushing, grabbing, throwing things, cursing or verbal aggression, spitting, tearing things/destroying property, hurting self or others, screaming); 2) Physically Non-Aggressive Behavior (pacing, trying to get to a different place, general restlessness, inappropriate dressing or disrobing, handling things inappropriately, performing repetitious mannerisms); 3) Verbally Agitated Behavior (complaining, constant requests for attention, repetitive questions, negativism); and 4) Hiding and Hoarding. Confirmatory factor analysis indicated that the four-factor solution was a reasonable fit to the data. CONCLUSION: Four factors emerged on the CMAI in nursing home patients with behavioral and psychological symptoms of dementia. The results obtained converge reasonably with previous publications concerning the factor structure of the CMAI, which, taken together, suggest a fairly robust factor structure for the instrument.  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