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   1607904篇
  免费   132109篇
  国内免费   2588篇
耳鼻咽喉   21697篇
儿科学   53070篇
妇产科学   46377篇
基础医学   228707篇
口腔科学   47287篇
临床医学   141856篇
内科学   315911篇
皮肤病学   34208篇
神经病学   130509篇
特种医学   65091篇
外国民族医学   474篇
外科学   244508篇
综合类   39806篇
现状与发展   3篇
一般理论   550篇
预防医学   123541篇
眼科学   36551篇
药学   121645篇
  3篇
中国医学   2980篇
肿瘤学   87827篇
  2018年   14872篇
  2016年   12983篇
  2015年   15120篇
  2014年   20779篇
  2013年   31570篇
  2012年   42865篇
  2011年   45070篇
  2010年   26529篇
  2009年   25503篇
  2008年   43330篇
  2007年   45553篇
  2006年   46350篇
  2005年   45000篇
  2004年   44388篇
  2003年   42463篇
  2002年   41521篇
  2001年   75829篇
  2000年   78490篇
  1999年   66553篇
  1998年   17802篇
  1997年   16414篇
  1996年   16380篇
  1995年   16076篇
  1994年   15127篇
  1993年   14271篇
  1992年   55561篇
  1991年   53916篇
  1990年   52662篇
  1989年   50929篇
  1988年   47308篇
  1987年   46631篇
  1986年   44377篇
  1985年   42938篇
  1984年   32115篇
  1983年   27629篇
  1982年   16191篇
  1981年   14488篇
  1980年   13598篇
  1979年   30509篇
  1978年   21119篇
  1977年   17816篇
  1976年   16742篇
  1975年   17619篇
  1974年   21548篇
  1973年   20718篇
  1972年   18895篇
  1971年   17815篇
  1970年   16330篇
  1969年   15312篇
  1968年   13975篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Intramedullary implants have decisive advantages in the treatment of femoral fractures in the vicinity of the hip joint: a torque that leads to a less pronounced varus position, implantation in the course of the relevant forces, and primary stability in the case of both stable and unstable fractures. Because of the constant developments in the implants available and the frequent failure to differentiate between stable and unstable fractures, some of the recommendations in the literature seem to contradict each other. However, precise analysis of the literature data show that stable fractures can be adequately treated with any technique, while unstable fractures fall in the domain of nailing systems. Since it is not possible to distinguish unequivocally between stable and unstable fractures, all trochanteric and subtrochanteric femoral fractures should be treated with a cephalomedullary nailing system.  相似文献   
995.
996.
997.
Chronic headaches are difficult to treat and represent the biggest challenge in headache centres. Mirtazapine has a prophylactic and ibuprofen an acute effect in tension-type headache. Combination therapy may increase efficacy and lower side effects. We aimed to evaluate the prophylactic effect of a combination of low-dose mirtazapine and ibuprofen in chronic tension-type headache. Ninety-three patients were included in the double-blind, placebo-controlled, parallel trial. Following a 4-week run-in period they were randomized to four groups for treatment with a combination of mirtazapine 4.5 mg and ibuprofen 400 mg, placebo, mirtazapine 4.5 mg or ibuprofen 400 mg daily for 8 weeks. Eighty-four patients completed the study. The primary efficacy parameter, change in area under the headache curve from run-in to the last 4 weeks of treatment, did not differ between combination therapy (190) and placebo (219), P  = 0.85. Explanatory analyses revealed worsening of headache already in the third week of treatment with ibuprofen alone. In conclusion, the combination of low-dose mirtazapine and ibuprofen is not effective for the treatment of chronic tension-type headache. Moreover, the study suggests that daily intake of ibuprofen worsens headache already after few weeks in chronic tension-type headache.  相似文献   
998.
HYPOTHESIS: Based on recent findings on the association between vascular risk factors and hippocampal atrophy, we hypothesized that hypertension and diabetes mellitus (DM) are associated with medial temporal lobe atrophy (MTA) in subjects without disability, independent of the severity of white matter hyperintensities. METHODS: In the Leukoaraiosis And DISability in the elderly (LADIS) study, we investigated the relationships between DM, hypertension, blood pressure and MTA in 582 subjects, stratified by white matter hyperintensity severity, using multinomial logistic regression. MTA was visually scored for the left and right medial temporal lobe (score 0-4), and meaned. RESULTS: Mean age was 73.5 years (sd 5.1), 54% was female. Of the subjects, 15% had DM, and 70% had a history of hypertension. The likelihood of having MTA score 3 was significantly higher in subjects with DM (OR 2.9; 95% CI: 1.1-7.8) compared with an MTA score of 0 (no atrophy). The odds ratio for MTA score 2 was not significantly increased (OR 1.8; CI: 0.9-4). Systolic and diastolic blood pressure and a history of hypertension were not associated with MTA. There was no interaction between DM and hypertension. Stratification on white matter hyperintensities (WMH) did not alter the associations. CONCLUSION: Our study strengthens the observation that MTA is associated with DM, independently of the amount of small vessel disease as reflected by WMH.  相似文献   
999.
There is growing evidence that obesity in women lead to a more severe form of hyperandrogenism and other endocrine abnormalities which may have some health implications later in life. Obese females are at higher risk for metabolic syndrome due to severe hyperandrogenemia. Calculated values for free testosterone are equivalent to those obtained by equilibrium dialysis, which is one of the reference measurement procedures (RMP) for estimation of free testosterone and may be capable of replacing values estimated using RMP's. For adult women correlations of body mass index (BMI) with calculated free (cFT) and bioavailable testosterone (cBT) are still rare, while these data are reported for peripubertal and adolescent girls. In this study we aimed to investigate the association between BMI and different androgen parameters (including calculated free and bioavailable testosterone, free androgen index, and sex hormone-binding globulin [SHBG]) in adult women with Hirsutism and with PCOS. In hirsute women with BMI > or = 25 kg/m2 measured total testosterone (TT) was significantly higher, SHBG was significantly lower and the calculated androgen parameter (FAI, cFT and cBT) were significantly higher compared to women with BMI < 25 kg/m2. In PCOS women with BMI > or = 25 kg/m2 TT was significantly higher, SHBG was significantly lower and the calculated androgen parameter (FAI, cFT and cBT) were also significantly higher compared to women with BMI < 25 kg/m2. In both the Hirsutism and PCOS-group there was a positive correlation between BMI and TT, cFT, and cBT, while BMI was negatively correlated with SHBG. In summary, in adult women with Hirsutism and PCOS obesity is associated with increased levels of TT and decreased levels of SHBG resulting in significant elevated calculated free and bioavailable testosterone levels. Obesity might lead to a more severe form of hyperandrogenism with elevated calculated free and bioavailable testosterone in the study population.  相似文献   
1000.
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