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   71338篇
  免费   3507篇
  国内免费   314篇
耳鼻咽喉   1453篇
儿科学   2322篇
妇产科学   1624篇
基础医学   9169篇
口腔科学   2433篇
临床医学   4901篇
内科学   17466篇
皮肤病学   2409篇
神经病学   5745篇
特种医学   1500篇
外国民族医学   1篇
外科学   8603篇
综合类   482篇
一般理论   21篇
预防医学   7196篇
眼科学   1314篇
药学   4986篇
中国医学   467篇
肿瘤学   3067篇
  2023年   531篇
  2022年   1370篇
  2021年   2717篇
  2020年   1276篇
  2019年   2352篇
  2018年   2757篇
  2017年   1633篇
  2016年   1587篇
  2015年   1767篇
  2014年   2667篇
  2013年   3678篇
  2012年   5153篇
  2011年   5511篇
  2010年   3090篇
  2009年   2602篇
  2008年   3902篇
  2007年   4075篇
  2006年   3765篇
  2005年   3804篇
  2004年   3441篇
  2003年   3144篇
  2002年   2852篇
  2001年   1613篇
  2000年   1757篇
  1999年   1454篇
  1998年   472篇
  1997年   420篇
  1996年   316篇
  1995年   289篇
  1994年   251篇
  1993年   185篇
  1992年   537篇
  1991年   438篇
  1990年   418篇
  1989年   316篇
  1988年   319篇
  1987年   289篇
  1986年   255篇
  1985年   241篇
  1984年   150篇
  1983年   149篇
  1982年   115篇
  1981年   129篇
  1980年   97篇
  1979年   143篇
  1978年   109篇
  1974年   106篇
  1971年   88篇
  1969年   88篇
  1968年   75篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
995.
The objective of this study is to establish whether there is an association between the presence of FCGR3A V(176) polymorphism with SLE or its manifestations. We included 94 patients according to the 1982 ACR criteria as well as 98 controls matched by age and gender. The 11 ACR diagnostic criteria were analyzed on the clinical files. The polymorphism FCGR3A V(176) was determined by direct sequencing. There was not an association between the polymorphism FCGR3A V(176) with SLE or its main manifestations. The allelic frequency for F(176) was: 0.80 and 0.72 in cases and controls, respectively (P?=?0.09, IC95%: 0.42?C1.07); and the genotypic frequency in the group of cases was: 0.65 for homozygotes F(176)/F(176), 0.30 for heterozygotes and 0.05 for the homozygotes V(176)/V(176), while for the control group it was 0.53, 0.39 and 0.08, respectively. The polymorphism FCGR3A V(176) is not associated with SLE or any of its manifestations in patients with SLE from the West of Mexico.  相似文献   
996.
997.
AIM: To analyze the effectiveness of the endoscopic therapy and to identify prognostic factors for recurrent bleeding.METHODS: Retrospective study of patients with gastrointestinal bleeding secondary to Dieulafoy’s lesion (DL) from 2005 to 2011. We analyzed the demographic characteristics of the patients, risk factors for gastrointestinal bleeding, endoscopic findings, characteristics of the endoscopic treatment, and the recurrence of bleeding. We included cases in which endoscopy described a lesion compatible with Dieulafoy. We excluded patients who had potentially bleeding lesions such as angiodysplasia in other areas or had undergone other gastrointestinal endoscopic procedures.RESULTS: Twenty-nine patients with DL were identified. Most of them were men with an average age of 71.5 years. Fifty-five percent of the patients received antiaggregatory or anticoagulant therapy. The most common location for DL was the stomach (51.7%). The main type of bleeding was oozing in 65.5% of cases. In 27.6% of cases, there was arterial (spurting) bleeding, and 6.9% of the patients presented with an adherent clot. A single endoscopic treatment was applied to nine patients (31%); eight of them with adrenaline and one with argon, while 69% of the patients received combined treatment. Six patients (20.7%) presented with recurrent bleeding at a median of 4 d after endoscopy (interquartile range = 97.75). Within these six patients, the new endoscopic treatment obtained a therapeutic success of 100%. The presence of arterial bleeding at endoscopy was associated with a higher recurrence rate for bleeding (50% vs 33.3% for other type of bleeding) [P = 0.024, odds ratio (OR) = 8.5, 95% CI = 1.13-63.87]. The use of combined endoscopic treatment prevented the recurrence of bleeding (10% vs 44.4% of single treatment) (P = 0.034, OR = 0.14, 95% CI = 0.19-0.99).CONCLUSION: Endoscopic treatment of DL is safe and effective. Adrenaline monotherapy and arterial (spurting) bleeding are associated with a high rate of bleeding recurrence.  相似文献   
998.
Neural stem cells (NSCs) are regarded as a promising therapeutic approach to protecting and restoring damaged neurons in neurodegenerative diseases (NDs) such as Parkinson's disease and Alzheimer's disease (PD and AD, respectively). However, new research suggests that NSC differentiation is required to make this strategy effective. Several studies have demonstrated that melatonin increases mature neuronal markers, which reflects NSC differentiation into neurons. Nevertheless, the possible involvement of mitochondria in the effects of melatonin during NSC differentiation has not yet been fully established. We therefore tested the impact of melatonin on NSC proliferation and differentiation in an attempt to determine whether these actions depend on modulating mitochondrial activity. We measured proliferation and differentiation markers, mitochondrial structural and functional parameters as well as oxidative stress indicators and also evaluated cell transplant engraftment. This enabled us to show that melatonin (25 μM) induces NSC differentiation into oligodendrocytes and neurons. These effects depend on increased mitochondrial mass/DNA/complexes, mitochondrial respiration, and membrane potential as well as ATP synthesis in NSCs. It is also interesting to note that melatonin prevented oxidative stress caused by high levels of mitochondrial activity. Finally, we found that melatonin enriches NSC engraftment in the ND mouse model following transplantation. We concluded that a combined therapy involving transplantation of NSCs pretreated with pharmacological doses of melatonin could efficiently restore neuronal cell populations in PD and AD mouse models depending on mitochondrial activity promotion.  相似文献   
999.
The relationship between OC and atherosclerosis in different clinical situations confirms the interplay that exists among bone cells and vascular system. The recently demonstrated effects of OC on glucose metabolism and visceral fat in healthy subjects and T2DM patients, contribute to the knowledge of the role of OC in the pathogenesis of cardiovascular disease.  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