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   275374篇
  免费   16097篇
  国内免费   698篇
耳鼻咽喉   3441篇
儿科学   7895篇
妇产科学   5860篇
基础医学   37612篇
口腔科学   11826篇
临床医学   20573篇
内科学   63447篇
皮肤病学   6725篇
神经病学   23887篇
特种医学   7883篇
外国民族医学   26篇
外科学   35152篇
综合类   1882篇
现状与发展   1篇
一般理论   103篇
预防医学   26541篇
眼科学   5247篇
药学   17694篇
中国医学   1092篇
肿瘤学   15282篇
  2023年   1453篇
  2022年   2280篇
  2021年   5854篇
  2020年   3686篇
  2019年   5520篇
  2018年   8103篇
  2017年   5801篇
  2016年   5650篇
  2015年   6670篇
  2014年   8675篇
  2013年   11351篇
  2012年   19469篇
  2011年   20361篇
  2010年   10134篇
  2009年   8562篇
  2008年   16324篇
  2007年   17035篇
  2006年   16199篇
  2005年   16322篇
  2004年   15242篇
  2003年   13806篇
  2002年   11482篇
  2001年   6790篇
  2000年   7312篇
  1999年   5676篇
  1998年   2090篇
  1997年   1685篇
  1996年   1659篇
  1995年   1437篇
  1994年   1354篇
  1993年   1216篇
  1992年   2909篇
  1991年   2785篇
  1990年   2477篇
  1989年   2470篇
  1988年   2228篇
  1987年   2061篇
  1986年   1952篇
  1985年   1918篇
  1984年   1429篇
  1983年   1139篇
  1982年   708篇
  1981年   655篇
  1980年   645篇
  1979年   1003篇
  1978年   699篇
  1977年   563篇
  1975年   599篇
  1974年   607篇
  1973年   594篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
91.
92.
93.
IntroductionScales for predicting venous thromboembolism (VTE) recurrence are useful for deciding the duration of the anticoagulant treatment. Although there are several scales, the most appropriate for our setting has not been identified. For this reason, we aimed to validate the DASH prediction score and the Vienna nomogram at 12 months.MethodsThis was a retrospective study of unselected consecutive VTE patients seen between 2006 and 2014. We compared the ability of the DASH score and the Vienna nomogram to predict recurrences of VTE. The validation was performed by stratifying patients as low-risk or high-risk, according to each scale (discrimination) and comparing the observed recurrence with the expected rate (calibration).ResultsOf 353 patients evaluated, 195 were analyzed, with an average age of 53.5 ± 19 years. There were 21 recurrences in 1 year (10.8%, 95% CI: 6.8%-16%). According to the DASH score, 42% were classified as low risk, and the rate of VTE recurrence in this group was 4.9% (95% CI: 1.3%-12%) vs. the high-risk group that was 15% (95% CI: 9%-23%) (p <.05). According to the Vienna nomogram, 30% were classified as low risk, and the rate of VTE recurrence in the low risk group vs. the high risk group was 4.2% (95% CI:0.5%-14%) vs. 16.2% (95% CI: 9.9%-24.4%) (p <.05).ConclusionsOur study validates the DASH score and the Vienna nomogram in our population. The DASH prediction score may be the most advisable, both because of its simplicity and its ability to identify more low-risk patients than the Vienna nomogram (42% vs. 30%).  相似文献   
94.
95.
We report on a 3‐year‐old girl with a microvesicular generalized rash in whom primary infection by parvovirus B19 was demonstrated by seroconversion. To our knowledge, this is the first instance of an eruption arising from parvovirus B19 with this peculiar clinical pattern.  相似文献   
96.
97.
98.
99.
100.
BACKGROUND Accurate detection of gastric infection by Helicobacter pylori(H.pylori) and premalignant lesions are important for effective provision of treatment,preventing the development of gastric neoplasia.Optical enhancement systems with optical magnification improved the identification of mucosal superficial and vascular patterns in patients with dyspepsia.AIM To evaluate an optical enhancement system with high-definition magnification,for diagnosis of normal gastric mucosa,H.pylori-associated gastritis,and gastric atrophy.METHODS A cross-sectional,nonrandomized study from November 2015 to April 2016 performed in a single-tertiary academic center from Ecuador.Seventy-two consecutive patients with functional dyspepsia according to the Rome III criteria,were tested for H.pylori using a stool antigen test and were assigned to an Hp+group or an Hp-control group.Esophagogastroduodenoscopy with highdefinition optical magnification and digital chromoendoscopy was performed,and patients were classified into 4 groups,in accordance to the microvasculararchitecture pattern of the mucosa.Interobserver and intraobserver agreement among operators were calculated.RESULTS Of the 72 participants,35 were Hp+ and 37 were Hp-.Among 10 patients with normal mucosal histology in biopsy samples,90% had a Type I pattern of microvascular architecture by endoscopy.Among participants with type IIa and type IIb patterns,significantly more were Hp+ than Hp-(32 vs 8),and most(31 out of 40) had histological diagnoses of chronic active gastritis.Two of the three participants with a histological diagnosis of atrophy had a type III microvascular pattern.The type I pattern predicted normal mucosa,type IIa–IIb predicted H.pylori infection,and type III predicted atrophy with sensitivities of 90.0%,91.4%,and 66.7%,respectively.The intraobserver and interobserver agreements had kappa values of 0.91 and 0.89,respectively.CONCLUSION High-definition optical magnification with digital chromoendoscopy is useful for diagnosis of normal gastric mucosa and H.pylori-associated gastritis with high accuracy,but further studies are needed to determine whether endoscopic diagnosis of gastric atrophy is feasible.  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