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   1602946篇
  免费   131603篇
  国内免费   2586篇
耳鼻咽喉   21656篇
儿科学   52961篇
妇产科学   46256篇
基础医学   227970篇
口腔科学   47217篇
临床医学   140986篇
内科学   315060篇
皮肤病学   34143篇
神经病学   130162篇
特种医学   64748篇
外国民族医学   474篇
外科学   243943篇
综合类   39800篇
现状与发展   3篇
一般理论   544篇
预防医学   122933篇
眼科学   36515篇
药学   121354篇
  3篇
中国医学   2980篇
肿瘤学   87427篇
  2018年   14802篇
  2016年   12919篇
  2015年   15061篇
  2014年   20702篇
  2013年   31410篇
  2012年   42626篇
  2011年   44837篇
  2010年   26391篇
  2009年   25342篇
  2008年   43058篇
  2007年   45306篇
  2006年   46118篇
  2005年   44747篇
  2004年   44140篇
  2003年   42239篇
  2002年   41330篇
  2001年   75718篇
  2000年   78361篇
  1999年   66409篇
  1998年   17742篇
  1997年   16339篇
  1996年   16318篇
  1995年   16026篇
  1994年   15079篇
  1993年   14226篇
  1992年   55443篇
  1991年   53795篇
  1990年   52574篇
  1989年   50849篇
  1988年   47233篇
  1987年   46574篇
  1986年   44300篇
  1985年   42860篇
  1984年   32044篇
  1983年   27573篇
  1982年   16149篇
  1981年   14440篇
  1980年   13568篇
  1979年   30467篇
  1978年   21075篇
  1977年   17768篇
  1976年   16706篇
  1975年   17590篇
  1974年   21497篇
  1973年   20681篇
  1972年   18855篇
  1971年   17772篇
  1970年   16291篇
  1969年   15271篇
  1968年   13952篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
OBJECTIVE: To evaluate the reproducibility of sonographic measurement of the lower uterine segment in pregnant women at term. METHODS: Two independent observers performed transabdominal sonography on 129 women between 36 and 38 weeks of gestation who had had a previous Cesarean section. Sonography was performed when the patients had a full and a half-full bladder; in 100 patients, the measurements were also performed transvaginally, with the patients having an empty bladder. Agreement was quantified by the intraclass correlation coefficient and, using a cut-off of 3.5 mm, by the kappa coefficient. RESULTS: The intraobserver agreement was generally high (intraclass correlation coefficient > 0.90). The interobserver agreement was higher on transvaginal (intraclass correlation coefficient, 0.94) compared with transabdominal (0.70 and 0.84, with full and half-full bladder, respectively) ultrasound. The kappa coefficient was 0.75 transvaginally, compared with 0.34 and 0.54 using the transabdominal approach, with full and half-full bladder, respectively. CONCLUSION: The agreement between two observers for sonographic transvaginal measurement of the lower uterine segment can be considered good, compared with poor to moderate agreement using the transabdominal approach.  相似文献   
74.
AIMS: To establish all-cause and cause-specific death rates, and risk factors for mortality in insulin-treated diabetic individuals living in the province of Canterbury, New Zealand. METHODS: Insulin-treated diabetic subjects (n = 995) on the Canterbury Diabetes Registry were followed up over 15 years and vital status determined. Death rates were standardized and hazard regression was used to model the effects of demographic covariates on relative survival time. RESULTS: There were 419 deaths in 11 226.3 person-years of follow-up with a standardized mortality ratio (SMR) of 2.0 (95% confidence interval (CI) 1.8-2.2). Relative mortality was greatest for the group aged 0-29 years (SMR 3.0 (95% CI 2.4-3.7)). After controlling for diabetes duration and gender, a 10-year increment in age of onset was associated with a 33% decrease in relative hazard (95% CI 29-36%), indicating that excess mortality due to diabetes declines with rising age of onset. After controlling for age of onset and gender, each 10-year increment in duration of diabetes is associated with a 26% decrease in relative hazard (95% CI 24-29%), indicating that with longer survival the mortality hazard approaches the general population hazard. Relative mortalities were increased for cardiovascular, renal and respiratory disease, but not malignancy. Relative mortality from acute metabolic complications was increased in the subgroup with age of onset of diabetes < 30 years and requiring insulin within 1 year of diagnosis. CONCLUSIONS: Mortality rates are high for insulin-treated diabetic individuals relative to the general population.  相似文献   
75.
Cidofovir is an acyclic nucleoside phosphonate with broad-spectrum activity against DNA viruses, including human papilloma virus (HPV). However, data on the efficacy of cidofovir in an immunosuppressive setting remain contradictory. We report for the first time on the promotion of the healing of recalcitrant warts in a patient with myelodysplastic syndrome with intravenous cidofovir treatment.  相似文献   
76.
The incidence of asthma has been reported to be associated with obesity. An alternative analysis, of net change in prevalence, does not require exclusion of those with asthma at baseline. Follow-up data were obtained from 9,552 participants in the European Community Respiratory Health Survey and the Swiss cohort Study on Air Pollution and Lung Disease in Adults. Incidence of asthma was analysed by proportional hazards regression, and net changes in symptoms and asthma status by generalised estimating equations, by obesity group. Incidence and net change in ever having had asthma were greater in females than in males, and in participants who remained obese compared with those who were never obese (hazard ratio 2.00, 95% confidence interval 1.25-3.20; excess net change 2.8%, 0.4-5.3% per 10 yrs). The effect of being obese on net change in diagnosed asthma was greater in females than in males, but for net change in wheeze without a cold it was greater in males. The present results are consistent with asthma being more frequently diagnosed in females, especially obese females. These findings may help to explain the reports of a stronger association between asthma and obesity in females than in males.  相似文献   
77.
78.
79.
80.
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