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   4225392篇
  免费   337693篇
  国内免费   13930篇
耳鼻咽喉   58811篇
儿科学   135032篇
妇产科学   110768篇
基础医学   652633篇
口腔科学   114132篇
临床医学   382897篇
内科学   763903篇
皮肤病学   106343篇
神经病学   350937篇
特种医学   163850篇
外国民族医学   503篇
外科学   649221篇
综合类   119307篇
现状与发展   23篇
一般理论   2564篇
预防医学   353924篇
眼科学   99037篇
药学   295251篇
  26篇
中国医学   11378篇
肿瘤学   206475篇
  2021年   56174篇
  2020年   35674篇
  2019年   58871篇
  2018年   74170篇
  2017年   56566篇
  2016年   62570篇
  2015年   75642篇
  2014年   110203篇
  2013年   175408篇
  2012年   122003篇
  2011年   127551篇
  2010年   125870篇
  2009年   127101篇
  2008年   113640篇
  2007年   121098篇
  2006年   129735篇
  2005年   124762篇
  2004年   124912篇
  2003年   115325篇
  2002年   104526篇
  2001年   149727篇
  2000年   144567篇
  1999年   134348篇
  1998年   70137篇
  1997年   66259篇
  1996年   64456篇
  1995年   59730篇
  1994年   53809篇
  1993年   50066篇
  1992年   96069篇
  1991年   92647篇
  1990年   89066篇
  1989年   86826篇
  1988年   80023篇
  1987年   78515篇
  1986年   73863篇
  1985年   72983篇
  1984年   61666篇
  1983年   55432篇
  1982年   46028篇
  1981年   43126篇
  1980年   40516篇
  1979年   53103篇
  1978年   44040篇
  1977年   38891篇
  1976年   36276篇
  1975年   36276篇
  1974年   39414篇
  1973年   37636篇
  1972年   35246篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
944.
Monatsschrift Kinderheilkunde - Fusionen und Übernahmen in der Pharmaindustrie haben zu einer Konzentration geführt, von der auch die Impfstoffproduktion mit nur noch wenigen global...  相似文献   
945.
Increasing numbers of arthroplasties are also accompanied by postoperative infections. The main purpose was to evaluate preoperative serum bilirubin levels between patients with and without infections after shoulder and knee arthroplasties. For this retrospective case-control single-center study, a total of 108 patients were extracted from a prospectively collected database. Eighteen patients with infections after shoulder (n = 8) and knee (n = 10) arthroplasty were matched by age, gender, and implant type in a 1:5-scenario to 90 patients (40 shoulders and 50 knees) without postoperative infection. Demographic data, preoperative blood parameters, and postoperative infection-related outcomes were evaluated. Total bilirubin was the only preoperative parameter significantly different between the infection (8.21 ± 3.25 μmol/L or 0.48 ± 0.19 mg/dL) and noninfection (10.78 ± 4.62 μmol/L or 0.63 ± 0.27 mg/dL; P = .014) group, while C-reactive protein and other liver parameters were similar between the groups. Significantly more controls (92.1%) had preoperative bilirubin levels above 8.72 μmol/L or 0.51 mg/dL than cases (7.9%; P = .007). The 5-year infection survival-rate was 65.6% for patients with preoperative bilirubin levels < 8.72 μmol/L or < 0.51 mg/dL and 91.2% with ≥ 8.72 μmol/L or ≥ 0.51 mg/dL. Mildly decreased preoperative bilirubin levels with a cutoff at 8.72 μmol/L or 0.51 mg/dL were significantly associated to patients with infections after shoulder and knee arthroplasty. There were no differences in other blood parameters or comorbidities between patients with infections and their matched-controls.  相似文献   
946.
Neurological Sciences - Chronic subdural haematoma (CSDH) is one of the most common neurosurgical pathologies. The recurrence of chronic subdural haematomas is an important concern, considering...  相似文献   
947.
ABSTRACT

Purpose

New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates.  相似文献   
948.
Rhinovirus (RV) infections are linked to the development and exacerbation of allergic diseases including allergic asthma. IgE, another contributor to atopic disease pathogenesis, has been shown to regulate DC antiviral functions and influence T cell priming by monocytes. We previously demonstrated that IgE-mediated stimulation of monocytes alters multiple cellular functions including cytokine secretion, phagocytosis, and influenza-induced Th1 development. In this study, we investigate the effects of IgE-mediated stimulation on monocyte-driven, RV-induced T cell development utilizing primary human monocyte-T cell co-cultures. We demonstrate that IgE crosslinking of RV-exposed monocytes enhances monocyte-driven Th2 differentiation. This increase in RV-induced Th2 development was regulated by IgE-mediated inhibition of virus-induced type I IFN and induction of IL-10. These findings suggest an additional mechanism by which two clinically significant risk factors for allergic disease exacerbations—IgE-mediated stimulation and rhinovirus infection—may synergistically promote Th2 differentiation and allergic inflammation.  相似文献   
949.
Abstract

This study was undertaken to compare the concentrations of pro- and anti-angiogenic growth factors, nitric oxide (NO) stable metabolites in maternal serum and embryonic left ventricular (LV) isovolumic relaxation time (IRT, ms) during the first trimester in two groups of women: with pregnancy conceived by assisted reproductive technologies (ART, n?=?39) and normally conceived (control group, n?=?68) pregnancy. The concentration of vasoconstrictor endothelin 1 was 45.5 times more in ART than in control group. On the contrary, the concentrations of NO stable metabolites in ART were 1.9 times less than in control women. The assessment of angiogenic suppressors in ART women demonstrates the decrease in s-endoglin concentration was 1.6 times and in soluble receptor to vascular endothelial growth factor concentration was 2.0 times in comparison with control group. There was a significant increase in LV IRT in ART embryos in comparison to control ones. These data suggest significant changes in pro- anti-angiogenic factors balance and increase in vascular impedance in ART-conceived embryos.  相似文献   
950.
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