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   6869篇
  免费   435篇
  国内免费   17篇
耳鼻咽喉   50篇
儿科学   107篇
妇产科学   113篇
基础医学   970篇
口腔科学   185篇
临床医学   772篇
内科学   1523篇
皮肤病学   91篇
神经病学   754篇
特种医学   258篇
外科学   1089篇
综合类   53篇
一般理论   3篇
预防医学   459篇
眼科学   117篇
药学   406篇
中国医学   7篇
肿瘤学   364篇
  2023年   42篇
  2022年   87篇
  2021年   186篇
  2020年   134篇
  2019年   152篇
  2018年   186篇
  2017年   168篇
  2016年   154篇
  2015年   189篇
  2014年   257篇
  2013年   365篇
  2012年   569篇
  2011年   604篇
  2010年   337篇
  2009年   315篇
  2008年   485篇
  2007年   492篇
  2006年   437篇
  2005年   447篇
  2004年   405篇
  2003年   343篇
  2002年   287篇
  2001年   51篇
  2000年   46篇
  1999年   62篇
  1998年   46篇
  1997年   35篇
  1996年   32篇
  1995年   35篇
  1994年   20篇
  1993年   23篇
  1992年   27篇
  1991年   26篇
  1990年   20篇
  1989年   13篇
  1988年   9篇
  1987年   20篇
  1986年   17篇
  1985年   15篇
  1984年   12篇
  1983年   9篇
  1981年   8篇
  1979年   23篇
  1978年   15篇
  1975年   13篇
  1973年   13篇
  1972年   8篇
  1969年   11篇
  1968年   13篇
  1967年   9篇
排序方式: 共有7321条查询结果,搜索用时 0 毫秒
71.
72.
73.
Enterotoxaemia is a disease with a high associated mortality rate, affecting beef and veal calves worldwide, caused by C. perfringens alpha toxin and perfringolysin. A longitudinal study was conducted to determine the dynamics of antibodies against these toxins in 528 calves on 4 beef and 15 veal farms. The second study aimed to determine the effect of solid feed intake on the production of antibodies against alpha toxin and perfringolysin. The control group only received milk replacer, whereas in the test group solid feed was provided. Maternal antibodies for alpha toxin were present in 45% of the veal calves and 66% of the beef calves. In beef calves a fluent transition from maternal to active immunity was observed for alpha toxin, whereas almost no veal calves developed active immunity. Perfringolysin antibodies significantly declined both in veal and beef calves. In the second study all calves were seropositive for alpha toxin throughout the experiment and solid feed intake did not alter the dynamics of alpha and perfringolysin antibodies. In conclusion, the present study showed that veal calves on a traditional milk replacer diet had significantly lower alpha toxin antibodies compared to beef calves in the risk period for enterotoxaemia, whereas no differences were noticed for perfringolysin.  相似文献   
74.
75.
76.
Organ damage in sickle cell disease (SCD) is a crucial determinant for disease severity and prognosis. In a previous study, we analyzed the prevalence of SCD‐related organ damage and complications in adult sickle cell patients. We now describe a seven‐year follow‐up of this cohort.All patients from the primary analysis in 2006 (n = 104), were included for follow‐up. Patients were screened for SCD‐related organ damage and complications (microalbuminuria, renal failure, elevated tricuspid regurgitation flow velocity (TRV) (≥2.5 m/seconds), retinopathy, iron overload, cholelithiasis, avascular osteonecrosis, leg ulcers, acute chest syndrome (ACS), stroke, priapism and admissions for vaso‐occlusive crises (VOC) biannually. Upon 7 years of follow‐up, progression in the prevalence of avascular osteonecrosis (from 12.5% to 20.4%), renal failure (from 6.7% to 23.4%), retinopathy (from 39.7% to 53.8%) was observed in the whole group. In HbSS/HbSβ0‐thal patients also progression in microalbuminuria (from 34% to 45%) and elevated TRV (from 40% to 48%) was observed while hardly any progression in the prevalence of cholelithiasis, priapism, stroke or chronic ulcers was seen. The proportion of patients with at least one episode of ACS increased in the group of HbSS/HbSβ0‐thal patients from 32% to 49.1%. In conclusion, 62% of the sickle cell patients in this prospective cohort study developed a new SCD‐related complication in a comprehensive care setting within 7 years of follow‐up. Although the hospital admission rate for VOC remained stable, multiple forms of organ damage increased substantially. These observations underline the need for continued screening for organ damage in all adult patients with SCD.  相似文献   
77.
78.
Paroxysmal nocturnal hemoglobinuria, aplastic anemia, and myelodysplastic syndrome are a spectrum of acquired marrow failure, having a common pathologic thread of both immune dysregulation and the development of abnormal hematopoiesis. Allogeneic hematopoietic cell transplantation plays a critical role in the treatment of these disorders and, for many patients, is the only treatment modality with demonstrated curative potential. In recent years, there have been many breakthroughs in the understanding of the pathogenesis of these uncommon disorders. The subsequent advances in non-transplant therapies, along with concurrent improvement in outcomes after hematopoietic cell transplantation, necessitate continual appraisal of the indications, timing, and approaches to transplantation for acquired marrow failure syndromes. We review here contemporary and critical new findings driving current treatment decisions.  相似文献   
79.
Widespread microvascular injury followed by vessel obstruction may lead to disseminated intravascular coagulation (DIC). We describe a murine model wherein leukocytes interacting with inflamed microvessels in vivo are activated by antibodies. Treatment of tumor necrosis factor alpha (TNF-alpha)-primed mice with anti-Ly-6G antibodies reproduced many of the features of septic or traumatic shock including microvessel obstruction and coagulation, severe vasculitis, respiratory difficulties, and vascular leakage. Mice lacking either E-selectin or P-selectin were protected from this reaction as were animals treated with a combination of either selectin-blocking antibodies and heparin or a selectin antagonist plus heparin. Combined blockade of leukocyte/platelet adhesion and coagulation may provide convincing protection in DIC.  相似文献   
80.
Short-term treatment of gastroesophageal reflux disease   总被引:2,自引:0,他引:2       下载免费PDF全文
OBJECTIVE: To investigate the efficacy of acid suppressant drugs in the empirical treatment of gastroesophageal reflux disease (GERD) and in the treatment of endoscopy-negative reflux disease (ENRD). DESIGN: medline, embase, and the Cochrane Controlled Trials Register were searched. Bibliographies were reviewed. SETTING: Studies were eligible that compared the short-term use of proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H2RAs) with each other or with placebo in adults with GERD who were enrolled irrespective of endoscopic findings (empirical cases) or in whom endoscopy showed no signs of esophagitis (endoscopy-negative cases). MEASUREMENTS: Of 1,408 studies, only 13 could be included for meta-analysis. Data on 3,433 patients empirically treated for GERD and 2,520 patients treated for ENRD were extracted. The primary endpoint was relief of heartburn. MAIN RESULTS: In the empirical treatment of GERD, the summary relative risk (sRR) for symptom relief from H2RAs versus placebo was 0.77 (95% confidence interval [95% CI], 0.60 to 0.99). RR in the only placebo-controlled PPI trial was 0.35 (95% CI, 0.26 to 0.46). The sRR for standard dose PPIs versus H2RAs was 0.55 (95% CI, 0.44 to 0.68). In treatment of ENRD, both PPIs (sRR, 0.64; 95% CI, 0.52 to 0.79) and H2RAs (sRR, 0.78; 95% CI, 0.62 to 0.97) were superior to placebo, and PPIs were superior to H2RAs (sRR, 0.81; 95% CI, 0.70 to 0.95). CONCLUSIONS: Acid suppressant therapy (with a PPI or an H2RA) is more effective than placebo for short-term relief of heartburn in patients with persistent symptoms who are treated empirically for GERD and in those in whom esophagitis was excluded after endoscopy. The benefit of PPIs compared with H2RAs is more pronounced in patients treated empirically.  相似文献   
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