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   618篇
  免费   53篇
  国内免费   10篇
耳鼻咽喉   1篇
儿科学   32篇
妇产科学   1篇
基础医学   71篇
口腔科学   6篇
临床医学   72篇
内科学   94篇
皮肤病学   11篇
神经病学   30篇
特种医学   184篇
外科学   24篇
综合类   7篇
预防医学   43篇
眼科学   5篇
药学   68篇
  1篇
中国医学   13篇
肿瘤学   18篇
  2021年   10篇
  2020年   7篇
  2019年   4篇
  2018年   16篇
  2017年   7篇
  2016年   3篇
  2015年   8篇
  2014年   9篇
  2013年   19篇
  2012年   20篇
  2011年   28篇
  2010年   22篇
  2009年   23篇
  2008年   19篇
  2007年   20篇
  2006年   24篇
  2005年   13篇
  2004年   19篇
  2003年   17篇
  2002年   15篇
  2001年   21篇
  2000年   16篇
  1999年   16篇
  1998年   24篇
  1997年   17篇
  1996年   30篇
  1995年   18篇
  1994年   23篇
  1993年   17篇
  1992年   8篇
  1991年   7篇
  1990年   6篇
  1989年   18篇
  1988年   15篇
  1987年   22篇
  1986年   14篇
  1985年   15篇
  1984年   10篇
  1983年   14篇
  1982年   11篇
  1981年   11篇
  1980年   9篇
  1979年   9篇
  1978年   3篇
  1977年   6篇
  1976年   9篇
  1975年   6篇
  1974年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有681条查询结果,搜索用时 15 毫秒
31.
Objectives: To determine individual differences in the impact of illness on the change in performance of swimmers in international competitions. Methods: Subjects were members of the Australian swimming team (33 male and 39 female, aged 15–27 years). Swimmers provided a weekly seven day recall of symptoms of illness during final six weeks of preparations for international competition over a three year period. Swimmers were categorised as either ill (one or more episodes of illness) or healthy. The measure of performances was the international point score. Mean changes in points score were calculated for healthy and ill swimmers between a national championship and an international competition (∼16 weeks later). Likelihoods of substantial effects of illness on an individual''s true change in performance (beneficial/trivial/harmful) were estimated from means and standard deviations, assuming a smallest substantial change of 6 points. Results: Illness was reported before international performances by 38% of female and 35% of male swimmers. For female swimmers the change in performance was –3.7 (21.5) points (mean (SD)) with illness and –2.6 (19.0) points when healthy; for male swimmers the changes were –1.4 (17.5) points with illness and 5.6 (13.2) points when healthy. The likelihoods that illness had a substantial beneficial/trivial/harmful effect on performance of an individual swimmer were 32%/31%/37% for female and 17%/31%/52% for male participants (90% confidence limits ∼±10% to 20%). Conclusions: Although mild illness had only a trivial mean effect on female swimmers and a small harmful mean effect on male swimmers, there were substantial chances of benefit and harm for individuals.  相似文献   
32.
A comprehensive review of shoulder impingement reveals numerous causes, contributing factors, and therapeutic options for the resolution of symptoms and return to optimal shoulder function. The clinical diagnosis of shoulder impingement is rather straightforward, but the challenge arises in identifying causative factors and directing treatment options to alleviate symptoms and restore normal function. Shoulder impingement occurs when the space between the proximal humerus and the coracoacromial arch is narrowed such that the transversing tendons, primarily the supraspinatus and to a lesser degree, the infraspinatus, are injured. As the most diagnosed shoulder ailment an understanding of shoulder anatomy, supporting musculature and function, inciting factors, and individual demands are critical in directing the appropriate treatment plan. Medications, therapeutic exercise and surgical interventions all have their place in the treatment of shoulder impingement.  相似文献   
33.
OBJECT: Cerebral vasospasm is a common cause of morbidity and death following aneurysmal subarachnoid hemorrhage (SAH). Previous research has shown that bilirubin oxidation products (BOXes) are present in the cerebral spinal fluid in patients with SAH-induced cerebral vasospasm and can contribute to vasoconstriction and vasospasm in vitro and in vivo. The events leading to cerebral vasospasm are not understood; however, one component of the occlusion may be due to vascular remodeling. In this study the authors have investigated the actions of BOXes, okadaic acid ([OA], a phosphatase inhibitor), and phorbol-12 myristate-13 acetate ([PMA], a protein kinase activator) on vascular smooth-muscle cell (VSMC) morphology and metabolism. METHODS: Immunohistochemical analysis was performed to assess VSMC morphology and alpha-smooth-muscle actin (alphaSMA) distribution following the application of BOXes, OA, or PMA. Changes in the level of lactate dehydrogenase (LDH) release and oxidative metabolism were also measured. The BOXes, OA, or PMA caused VSMCs to change their shape and exhibit altered alphaSMA distribution. These treatments increased LDH release (p < 0.05), which is an index of increased cell stress. Oxidative metabolism significantly increased at low and high doses of BOXes, that is, 143 +/- 8.5% and 180 +/- 11.8%, respectively (p < 0.0001). Both PMA and OA also caused a significant increase in metabolism. CONCLUSIONS: The authors concluded that BOXes, OA, and PMA alter VSMC morphology and metabolic activity, events that have been observed during vascular remodeling. Although the mechanism remains unclear, the results indicate that BOXes may play a role in the vascular remodeling that occurs following aneurysmal SAH.  相似文献   
34.
35.
The relationship between quality and outcomes in routine depression care   总被引:3,自引:0,他引:3  
OBJECTIVE: This longitudinal, nonexperimental study examined whether depression treatment provided in concordance with guidelines developed by the Agency for Healthcare Research and Quality (AHRQ) is associated with improved clinical outcomes. METHODS: The medical, insurance, and pharmacy records of a community-based sample of 435 subjects who screened positive for current major depression were abstracted to ascertain whether depression treatment was received and whether it was provided in accordance with AHRQ guidelines. Regression analyses estimated the impact of guideline-concordant treatment on the change in depression severity and on mental and physical health over a six-month period. An instrumental variables analysis was used to check the sensitivity of the results to selection bias. RESULTS: A total of 106 subjects were treated for depression by 105 different primary care and specialty providers. Sixty percent of the sample had current major depression, and about 40 percent had subthreshold depression. Only 29 percent of the patients received guideline-concordant treatment. For patients with major depression, guideline-concordant care was significantly and substantially associated with improved depression severity but not with improvements in overall mental or physical health. The instrumental variables analysis indicated that the standard regression analysis underestimated the treatment effect by 21 percent. For those with subthreshold depression, guideline-concordant care was not associated with improved outcomes. DISCUSSION AND CONCLUSIONS: This community-based, nonexperimental study found a positive relationship between the quality of care for depression and clinical outcomes for patients with major depression in routine practice settings.  相似文献   
36.
PURPOSE: Exercise and training are known to elicit changes in mucosal humoral immunity, but whether these alterations have any impact on competitive performance remains unclear. This investigation examined relationships between salivary immunoglobulin (Ig) concentration, the incidence of respiratory tract illness (RTI), and competitive performance in elite swimmers. METHODS: Forty-one members of the Australian Swimming Team (21 males and 20 females) aged 15-27 yr were monitored during preparations for the 1998 Commonwealth Games. Twenty-five coaches and staff (19 males and 6 females) aged 32-65 yr, serving as "environmental controls," were also monitored. Salivary IgA, IgM, and IgG and albumin concentration (mg.L-1) were measured in both groups in May 1998 and again in August 1998, 17 d before competition. Subjects were categorized as "ill" (at least one RTI) or "healthy". RESULTS: There were no significant changes in salivary IgA, IgM, or IgG concentration in the swimmers between May and August, nor were there any differences between healthy (N = 23) and ill (N = 18) swimmers. There was a significant positive relationship between IgM and performance in the male swimmers (r = 0.85, P < 0.001) but not for any other parameter. There was no significant difference in performance between ill and healthy swimmers (P = 0.11). Gold medal winners (N = 9) had higher IgM levels than other swimmers (N = 32) in May (P = 0.02) and higher IgG in August (P = 0.02). CONCLUSION: These data indicate that a season of training by elite swimmers did not alter salivary immunoglobulin concentrations, and the presence of RTI had no significant impact on competitive performance.  相似文献   
37.
Serum thyrotrophin (TSH) was estimated by double-antibody radioimmunoassay in 200 children aged 2 months to 16 years with normal thyroid function. There was no apparent variation in TSH with age or sex and only 4 children had TSH levels greater than 5 muU/ml. High TSH values were obtained in 9 children with primary hypothyroidism, in 3 children with thyroiditis, and in one girl with a lingual thyroid. Moderately raised TSH was found in 3 girls with thyroiditis, 2 brothers with goitres due to enzyme defect, and a girl with an ectopic thyroid. In one girl with a defect of iodine organification and in 3 boys with thyroxine binding globulin deficiency the TSH levels were normal despite very low serum thyroxine values. Serum TSH was also estimated in 20 children during treatment for primary hypothyroidism. 3 of these children showed slightly raised TSH levels despite apparently adequate replacement therapy with L-thyroxine. One girl showed a very high TSH level 3 weeks after treatment had been temporarily withdrawn.  相似文献   
38.
39.
Epidemic dropsy is a potentially life‐threatening condition resulting from the ingestion of argemone oil derived from the seeds of Argemone mexicana Linn. Exposure to argemone oil is usually inadvertent, arising from mustard cooking oil adulteration. Sanguinarine, an alkaloid present in argemone oil, has been postulated as a causative agent with the severity of epidemic dropsy correlating with plasma sanguinarine levels. Cases of epidemic dropsy have also been reported following the topical application of argemone containing massage oil. Black salve, a topical skin cancer therapy also contains sanguinarine, but at significantly higher concentrations than that reported for contaminated massage oil. Although not reported to date, a theoretical risk therefore exists of black salve inducing epidemic dropsy. This literature review explores the presentation and pathophysiology of epidemic dropsy and assesses the risk of it being induced by black salve.  相似文献   
40.
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