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   6438篇
  免费   400篇
  国内免费   53篇
耳鼻咽喉   29篇
儿科学   94篇
妇产科学   69篇
基础医学   1017篇
口腔科学   147篇
临床医学   473篇
内科学   1405篇
皮肤病学   79篇
神经病学   777篇
特种医学   213篇
外科学   1070篇
综合类   28篇
现状与发展   1篇
一般理论   2篇
预防医学   338篇
眼科学   189篇
药学   474篇
中国医学   12篇
肿瘤学   474篇
  2024年   4篇
  2023年   42篇
  2022年   48篇
  2021年   236篇
  2020年   131篇
  2019年   199篇
  2018年   201篇
  2017年   123篇
  2016年   173篇
  2015年   209篇
  2014年   294篇
  2013年   328篇
  2012年   564篇
  2011年   569篇
  2010年   311篇
  2009年   272篇
  2008年   471篇
  2007年   461篇
  2006年   424篇
  2005年   405篇
  2004年   396篇
  2003年   330篇
  2002年   300篇
  2001年   30篇
  2000年   12篇
  1999年   31篇
  1998年   36篇
  1997年   51篇
  1996年   23篇
  1995年   28篇
  1994年   15篇
  1993年   18篇
  1992年   13篇
  1991年   16篇
  1990年   7篇
  1989年   7篇
  1988年   5篇
  1987年   7篇
  1985年   5篇
  1984年   5篇
  1983年   7篇
  1982年   5篇
  1981年   5篇
  1978年   8篇
  1977年   4篇
  1976年   8篇
  1975年   4篇
  1964年   4篇
  1961年   7篇
  1960年   5篇
排序方式: 共有6891条查询结果,搜索用时 31 毫秒
1.
2.
3.
ObjectiveTo determine the outcomes of patients with a quadricuspid truncal valve (TV) and durability of TV repair.MethodWe reviewed 56 patients with truncus arteriosus and a quadricuspid TV who underwent complete repair between 1979 and 2018.ResultsTV insufficiency was present in 39 patients (mild, n = 22; moderate, n = 14; and severe, n = 3). Fourteen patients had concomitant TV surgery. Early mortality in patients who had concomitant TV surgery was 14% (2 out of 14 patients) and overall survival was 77.1% ± 11.7% at 15 years. Freedom from TV reoperation was 30.3% ± 14.6% at 15 years. Early mortality in patients who did not undergo concomitant TV surgery was 9.5% (4 out of 42 patients) and overall survival was 74.9% ± 6.9% at 15 years. Progression of TV insufficiency requiring TV surgery occurred in 16.7% (7 out of 42 patients). Freedom from TV reoperation was 77.1% ± 7.8% at 15 years. The most common method of repair was tricuspidization of the TV. Freedom from TV reoperation was 64.3% ± 21.0% at 10 years after tricuspidization and 0% at 6 years after other types of TV surgery. Overall follow-up was 97.6% (41 out of 42 patients) complete for survivors with median follow-up of 16.6 years. At last follow-up there was no TV insufficiency in 16 patients, mild insufficiency in 24 patients, and moderate insufficiency in 1 patient.ConclusionsMore than one-third of patients with a quadricuspid TV require TV surgery. Tricuspidization of the quadricuspid TV appears to be a durable repair option with good long-term outcomes.  相似文献   
4.
5.
Abstract

Endometriosis is currently considered as one of the most common diseases associated with infertility. A controversial issue is whether endometriosis per se exerts a detrimental effect on IVF outcomes. Failure of implantation due to endometriosis-associated infertility is a contradictory and widely discussed burden nowadays. The purpose of the study is to assess the quality of embryos and implantation rate in women with infertility associated with endometriosis. The study included infertile reproductive aged women, between 26 and 40 years who underwent IVF and ICSI procedures. The patients were divided into two groups: group I (n?=?70) involved 70 patients with recurrent unilateral endometriomas, II control group (n?=?50) with tubal factor infertility. The quality of the retrieved embryos was assessed according to the generally accepted classification of Gardner, indicating the rate of implantation in each group. Embryo transfer was performed in case of high quality embryos. Assessing the ovarian reserve indicators, in the group I patients with recurrent unilateral endometriomas the serum level of AMH was significantly lower (2.1?±?1.75 vs. 3.2?±?1.4, p?<?.005), as well as the number of retrieved oocytes (8.1?±?3.9 and 10.1?±?6.8, p?<?.005). The analysis of the results demonstrated that the duration of stimulation in the group patients with recurrent unilateral endometriomas was significantly higher in comparison with the group II (12.2?±?1.8 and 10.2?±?1.6 days, p?<?.001). Nevertheless, the number of good quality embryos retrieved was comparable in both groups (2.2?±?1.5 and 2.8?±?1.8). In the group I patients with recurrent unilateral endometriomas, there was a statistically significant decrease of implantation rate (17.1% vs. 24% p?<?.005). The results of the study revealed no statistical difference in embryo quality in the study cohort. However, it is important to note that a statistically significant difference in implantation rate in the group of endometriosis-associated infertility compared was obtained 1.5 times lower than in the control group (15.8% vs. 24.0% p?<?.005). The achieved results demonstrated an adverse IVF outcome in infertile women with recurrent endometrioma compared to the control group.  相似文献   
6.
7.
8.
9.
ABSTRACT

Using nationally representative data from the National Longitudinal Study of Adolescent Health (a.k.a., Add Health), this study examines the impact of school climate and share of vulnerable groups of students on self-perceived discrimination and violence involvement in high school. Violence involvement is operationalized as victimization and perpetration of physical violence. Five categories of vulnerability status are analyzed: the emotionally disabled, learning disabled, physically disabled, obese and LGB. Results suggest that relatively higher odds of violence involvement for individuals who were members of vulnerable groups as adolescents are fully explained by school climate and an extensive set of individual-level controls. While the share of vulnerable groups in school is not consistently correlated with violence involvement, school climate is found to be highly predictive of self-perceived discrimination and violence involvement. Consequently, we believe that improving school climate is the most effective strategy for reducing violence involvement of vulnerable youth in school.  相似文献   
10.
Hepatocellular carcinoma(HCC) is the most common primary hepatic malignancy, which usually arises in cirrhotic liver. When the typical enhancement pattern, consisting of late arterial hyperenhancement followed by washout, is present in nodules larger than 1 cm, HCC can be confidently diagnosed without the need for tissue biopsy. Nevertheless, HCC can display an atypical enhancement pattern, either as iso or hypovascular lesion, or hypervascular lesion without washout. Not only the enhancement pattern of HCC could be atypical, but also a variety of histological types of HCC, such as steatotic, scirrhous, fibrolamellar, or combined hepatocellular-cholangiocellular carcinoma could raise diagnostic dilemmas. In addition, distinct morphological types of HCC or different growth pattern can occur. Awareness of these atypical and rare HCC presentations on magnetic resonance imaging is important for accurate differentiation from other focal liver lesions and timely diagnosis, which allows optimal treatment of patients.  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