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   727篇
  免费   46篇
  国内免费   1篇
耳鼻咽喉   5篇
儿科学   23篇
妇产科学   15篇
基础医学   105篇
口腔科学   16篇
临床医学   58篇
内科学   143篇
皮肤病学   11篇
神经病学   15篇
特种医学   61篇
外科学   119篇
综合类   40篇
预防医学   52篇
眼科学   18篇
药学   54篇
  1篇
中国医学   2篇
肿瘤学   36篇
  2023年   5篇
  2022年   8篇
  2021年   7篇
  2020年   11篇
  2019年   18篇
  2018年   19篇
  2017年   8篇
  2016年   15篇
  2015年   18篇
  2014年   27篇
  2013年   36篇
  2012年   27篇
  2011年   40篇
  2010年   23篇
  2009年   16篇
  2008年   29篇
  2007年   36篇
  2006年   39篇
  2005年   29篇
  2004年   34篇
  2003年   16篇
  2002年   23篇
  2001年   22篇
  2000年   24篇
  1999年   17篇
  1998年   14篇
  1997年   25篇
  1996年   17篇
  1995年   10篇
  1994年   16篇
  1993年   13篇
  1992年   21篇
  1991年   14篇
  1990年   9篇
  1989年   15篇
  1988年   6篇
  1987年   9篇
  1986年   4篇
  1985年   5篇
  1983年   5篇
  1981年   3篇
  1980年   4篇
  1978年   3篇
  1977年   3篇
  1975年   3篇
  1974年   3篇
  1972年   3篇
  1970年   2篇
  1969年   5篇
  1967年   3篇
排序方式: 共有774条查询结果,搜索用时 0 毫秒
61.
62.
63.
In this dose-ranging, randomised, multinational, multicentre, double-blind, placebo-controlled, parallel group study, 431 patients treated a single migraine attack with study medication: sumatriptan suppository 6 mg, 12.5 mg, 25 mg, 50 mg, 100 mg, or placebo. Patients were treated in the clinic with a single dose in suppository form. All doses of sumatriptan, except 6 mg, were significantly better than placebo (p < 0.004) and achieved similar rates of headache relief within two hours of dosing. The highest response rate was in the 25 mg group (72%) compared with placebo (37%) (p < 0.001). Fewer patients required rescue medication in the active groups (1% 100 mg to 13% 6 mg) compared with placebo (17%), and more patients were able to work and function normally two hours after dosing (41%, 100 mg; 20%, placebo). The overall incidence of adverse events was similar in the placebo, 6 mg and 12.5 mg groups (14-17%) but higher in the 25 mg, 50 mg and 100 mg groups (25%, 32% and 29% respectively). Analysis of plasma sumatriptan levels indicated rapid rectal absorption for all doses (median tmax = 1.0 hr). It is concluded that sumatriptan, in doses above 6 mg, is an effective and well tolerated treatment for acute migraine. From this study doses of 12.5 mg and 25 mg sumatriptan were identified as having the best efficacy/safety profile and were evaluated further.  相似文献   
64.
65.
To evaluate the ability of two graphologists and two practising internists not trained in graphology to differentiate letters written by subjects who have attempted to commit suicide by self-poisoning and healthy volunteers, we performed a maximal blind controlled study vs. healthy volunteers. Forty fully recovered patients who had attempted to commit suicide and 40 healthy volunteers wrote and signed a short letter or story not related to the parasuicide or their mental health status. The evaluators classified the 80 letters as 'suicide' or 'no suicide' in an intention-to-treat analysis. Letters expressing sadness were subsequently excluded for a per-protocol analysis. Correct diagnosis of suicide and of healthy controls was made in, respectively, 32 of 40 and 33 of 40 letters by the graphologists and in 27 of 40 and 34 of 40 letters by the internists. After the exclusion of 12 letters expressing sadness, the sensitivity, specificity, positive predictive value and negative predictive value were, respectively, 73, 88, 81 and 82% for the graphologists and 53, 89, 80 and 71% for the internists. Both classified the letters with significantly more effectiveness than chance (p < 0.001) with no statistically significant difference between the two groups of evaluators. We concluded that graphological analysis is able to differentiate letters written by patients who attempt suicide from those written by healthy controls. This technique shows an acceptable degree of accuracy and could therefore become an additional discharge or decision-making tool in Psychiatry or Internal Medicine.  相似文献   
66.
DNA damage associated with the trypanocidal activity of megazol [2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole] was shown in experiments in which DNA repair-deficient RAD51(-/-) Trypanosoma brucei mutants were found to be hypersensitive to the drug. Parasites resistant to megazol were selected and showed modest cross-resistance to other trypanocides, although neither drug efflux nor changes to intracellular thiols correlated with resistance.  相似文献   
67.
This study compared the analgesic efficacy and safety of the cyclo-oxygenase-2 specific inhibitor celecoxib with the non-specific non-steroidal anti-inflammatory drug, naproxen, in patients with acute shoulder pain. Adult patients with shoulder pain, onset within the previous 14 days and shoulder pain of > or = 40 mm on a 100 mm visual analogue scale (VAS), were treated with oral doses of celecoxib or naproxen for 14 days and followed by a visit at day 42 in a double-blind, randomized study. The primary efficacy assessment was change in maximum pain at rest on a 100 mm VAS at day 14 compared with baseline. In addition, secondary efficacy pain and functional assessments were analysed at baseline, day 14 and day 42. A total of 202 patients were included in the trial (99 celecoxib 400 mg/day; 103 naproxen 1 g/day). The difference in change from baseline at day 14 in maximum pain at rest was not statistically significant between the two treatment groups, but was numerically higher for celecoxib than for naproxen (-47.9 +/- 2.5 versus -42.3 +/- 2.5, respectively). According to the limits of the 95% confidence interval of the difference between groups (-12.52; 1.38), celecoxib appeared to be at least as effective as naproxen. All secondary efficacy measures followed the same pattern, showing similarity between the two treatments with a trend in favour of celecoxib. The incidences of adverse events were similar for both groups. Fewer patients experienced epigastric pain with celecoxib (seven patients versus 14 with naproxen). This adverse event led to discontinuation in two patients receiving celecoxib and five receiving naproxen. Celecoxib 400 mg/day was at least as effective as naproxen 1 g/day in managing pain in this condition.  相似文献   
68.
Origins of U.S. Hispanics. Implications for diabetes   总被引:15,自引:0,他引:15  
The purpose of this article was to characterize the origins of the United States Hispanic population and discuss the implications of these origins in the context of diabetes risk. Particular attention was focused on the genetic origins of the three major U.S. Hispanic groups, i.e., Mexican Americans, Puerto Ricans, and Cubans. The U.S. Census figures provided basic demographic information. Genetic marker data for ancestral populations were taken from a review of the literature and compendia. Genetic marker data for the Puerto Rican and Cuban populations were extracted from the literature. Genetic markers determined on approximately 1000 randomly selected Mexican Americans from Starr County, Texas, were taken as representative of the Mexican-American population. The Hispanic population is the second largest and fastest growing minority in the U.S. Estimates of the Hispanic population in 1988 indicated some 19.4 million residents, of whom 62% were classified as Mexican, 13% as Puerto Rican, and the remaining 25% as Cubans and others. Various lines of evidence can be used to characterize the Hispanic population and its origins. These include ethnohistory, self-assessment of ancestry, surname distributions, speech and cultural characteristics, quantitative traits, and genetic structure. Genetic data were used to estimate the contribution of putative ancestral populations to the contemporary gene pool. For Mexican Americans, 31% of the contemporary gene pool is estimated to be Native American derived, whereas 61 and 8% are Spanish and African derived, respectively. In Puerto Rico, the percentage of contributions of Spanish, Native American, and African admixture to the population are 45, 18, and 37%, respectively. For Cuba, the parallel estimates are 62, 18, and 20%. The high frequency of Native American-derived genes in the contemporary Hispanic population predict a higher frequency of non-insulin-dependent diabetes mellitus (NIDDM) under the assumption that genes are important in NIDDM etiology. Our results are consistent with the finding of the significant role of genes in determining risk.  相似文献   
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