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   2470篇
  免费   98篇
  国内免费   11篇
耳鼻咽喉   25篇
儿科学   180篇
妇产科学   133篇
基础医学   185篇
口腔科学   65篇
临床医学   227篇
内科学   537篇
皮肤病学   49篇
神经病学   136篇
特种医学   133篇
外科学   517篇
综合类   38篇
预防医学   53篇
眼科学   45篇
药学   111篇
中国医学   3篇
肿瘤学   142篇
  2023年   19篇
  2022年   33篇
  2021年   54篇
  2020年   23篇
  2019年   35篇
  2018年   51篇
  2017年   45篇
  2016年   66篇
  2015年   74篇
  2014年   88篇
  2013年   120篇
  2012年   168篇
  2011年   188篇
  2010年   108篇
  2009年   73篇
  2008年   185篇
  2007年   192篇
  2006年   177篇
  2005年   172篇
  2004年   166篇
  2003年   128篇
  2002年   91篇
  2001年   73篇
  2000年   47篇
  1999年   35篇
  1998年   14篇
  1997年   10篇
  1996年   11篇
  1995年   6篇
  1994年   11篇
  1992年   8篇
  1991年   11篇
  1990年   11篇
  1989年   5篇
  1988年   4篇
  1987年   11篇
  1986年   5篇
  1985年   10篇
  1984年   2篇
  1983年   8篇
  1981年   3篇
  1980年   2篇
  1979年   10篇
  1978年   4篇
  1977年   3篇
  1976年   2篇
  1975年   3篇
  1971年   3篇
  1967年   2篇
  1935年   1篇
排序方式: 共有2579条查询结果,搜索用时 0 毫秒
11.
12.
13.
14.
INTRODUCTION: The aim of this study was to compare serum levels of leptin in women with unexplained infertility with fertile subjects. MATERIAL AND METHOD: Serum leptin levels of 27 infertile and 30 fertile women on day 3 of the menstrual cycle were assessed and compared in this prospective age and body mass index (BMI) comparable controlled study. RESULTS: The mean age in the infertile group was 29.3 (range, 23-38), while this figure was 28.9 (range, 19-39) in the fertile group; the mean BMIs were 24.5 (range, 20.6-27.8) and 25.0 (range, 21.8-28.7), respectively. The mean serum leptin level was significantly higher in women with unexplained infertility compared with fertile subjects. Considering normal weight subjects, mean serum leptin levels were increased significantly in the unexplained infertile group compared with the fertile group (7.2 (range, 4.3-10.4) versus 3.5 (range, 1.9-6.2)ng/ml, respectively; p<0.0001, Mann-Whitney U-test). The significant increase in serum leptin levels was observed also in overweight patients (6.8 (range, 1.3-5.2) versus 3.3 (range, 4.2-8.9)ng/ml, respectively; p<0.0001, Mann-Whitney U-test). CONCLUSION: A significant difference in serum leptin levels between unexplained infertile and fertile women suggests that this cytokine may be involved in pathophysiology of unexplained infertility.  相似文献   
15.
Journal of Neurology - Evidence of immune-mediated neurological syndromes associated with the severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection is limited. We therefore...  相似文献   
16.

Background

Multifocal breast cancers (MFBCs) present a challenge to surgeons. Although its feasibility is still controversial, breast-conserving surgery (BCS) is not contraindicated for MFBCs. The investigators retrospectively evaluated the feasibility of BCS and reviewed histopathologic findings in patients with MFBC.

Methods

A total of 222 patients with MFBC who were treated with either BCS (119 patients) or mastectomy (103 patients) at a single institution between January 2002 and December 2011 were retrospectively evaluated.

Results

The median follow-up time was 55 months (range, 10 to 102 months). Lymphovascular invasion and lymph node involvement were significantly less frequent in the BCS group (48.8% vs 62.2% for lymphovascular invasion, P = .04; 52.1% vs 71.8% for lymph node involvement, P = .002). There were no differences in local recurrence rates between the 2 groups. The overall survival rates were 92% in the BCS group and 72% in the mastectomy group (P = .000).

Conclusions

BCS is a feasible and safe procedure for the removal of multifocal tumors. Extended lymphovascular invasion is associated with mortality in patients who undergo mastectomy.  相似文献   
17.
The relation between cancer and coagulation is the subject of investigation since a relation between tumor and thrombosis has been determined. Antithrombin III is an important thrombin inhibitor, and increased thrombin?Cantithrombin (TAT) complex levels activate coagulation. Activated thrombin activatable fibrinolysis inhibitor (TAFI) inhibits the conversion of plasminogen to plasmin. In addition, it directly inactivates plasmin. Defective fibrinolysis increases the risk of thrombosis. In this study, we evaluated homeostatic parameters, TAFI, and TAT levels in patients with gastric cancer applying to the medical oncology outpatient clinic. Fifty-two patients and 35 healthy controls were included. ELISA was used to measure TAFI and TAT complex levels. These were statistically higher in the patient group (p?<?0.05 and p?=?0.001, respectively). D-dimer levels were higher in stage IV (p?=?0.05). Correlations between lymph nodes and TAFI and TAT levels were examined. Weak but positive correlation between lymph nodes and TAFI was detected (R?=?0.452, p?=?0.027). TAFI and TAT levels were evaluated using relative operating characteristic analysis to differentiate the disease. TAT was more specific than TAFI according to this analysis (TAFI area under curve (AUC), 0.676; TAT AUC, 0.874). Thrombotic events and bleeding disorders need to be borne in mind in gastric cancer. This situation is due to the impairment of the balance between coagulation and fibrinolysis. Further studies are now needed to evaluate the effects of TAFI and TAT on survey and prognosis as well as the potential of these parameters as tumor markers for gastric cancer.  相似文献   
18.
19.
20.
Background and Aim:  The aim of this study was to determine whether resveratrol could prevent intestinal tissue injury induced by ischemia–reperfusion (I/R).
Methods:  Intestinal I/R was induced in rats' intestines by 60-min occlusion of the superior mesenteric artery, followed by a 60-min reperfusion. Thirty rats were divided into three groups as follows: sham (group 1), control (group 2), and the treatment groups (group 3). The rats in the treatment group received resveratrol both before ischemia and before reperfusion. In all groups, serum aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase levels were determined. Total antioxidant capacity (TAC), catalase, total oxidative status (TOS), oxidative stress index (OSI), and myeloperoxidase (MPO) in the intestinal tissue were measured. Intestinal tissue histopathology was also evaluated by light microscopy.
Results:  The levels of liver enzymes in group 3 were significantly lower than those in group 2 ( P  < 0.05). TAC in the intestinal tissue was significantly higher in group 3 than in group 2 ( P  < 0.05). TOS, OSI, and MPO in the intestinal tissue were significantly lower in group 3 than in group 2 ( P  < 0.05 for all). Histological tissue damage was milder in the resveratrol treatment group than in the control group.
Conclusions:  The results of this study indicated that resveratrol treatment limits the oxidative injury of the small intestine induced by I/R in rats. However, more precise investigations are required to evaluate the antioxidative effect of resveratrol on small intestine tissue damage in clinical and experimental models.  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