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   1620780篇
  免费   132979篇
  国内免费   2634篇
耳鼻咽喉   21916篇
儿科学   53286篇
妇产科学   46680篇
基础医学   230245篇
口腔科学   47532篇
临床医学   143199篇
内科学   318584篇
皮肤病学   34379篇
神经病学   131684篇
特种医学   65443篇
外国民族医学   474篇
外科学   247165篇
综合类   39878篇
现状与发展   3篇
一般理论   579篇
预防医学   124350篇
眼科学   36963篇
药学   122533篇
  3篇
中国医学   2991篇
肿瘤学   88506篇
  2018年   15545篇
  2016年   13494篇
  2015年   15677篇
  2014年   21602篇
  2013年   32474篇
  2012年   44333篇
  2011年   46580篇
  2010年   27275篇
  2009年   26173篇
  2008年   44316篇
  2007年   46546篇
  2006年   47206篇
  2005年   45769篇
  2004年   45037篇
  2003年   43018篇
  2002年   41962篇
  2001年   75772篇
  2000年   78389篇
  1999年   66443篇
  1998年   17822篇
  1997年   16401篇
  1996年   16347篇
  1995年   16039篇
  1994年   15098篇
  1993年   14240篇
  1992年   55443篇
  1991年   53787篇
  1990年   52566篇
  1989年   50847篇
  1988年   47228篇
  1987年   46563篇
  1986年   44296篇
  1985年   42854篇
  1984年   32042篇
  1983年   27576篇
  1982年   16153篇
  1981年   14442篇
  1980年   13573篇
  1979年   30468篇
  1978年   21069篇
  1977年   17766篇
  1976年   16696篇
  1975年   17576篇
  1974年   21488篇
  1973年   20673篇
  1972年   18854篇
  1971年   17772篇
  1970年   16290篇
  1969年   15269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