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   5390篇
  免费   480篇
  国内免费   9篇
耳鼻咽喉   62篇
儿科学   173篇
妇产科学   132篇
基础医学   753篇
口腔科学   46篇
临床医学   725篇
内科学   1044篇
皮肤病学   84篇
神经病学   600篇
特种医学   108篇
外科学   464篇
综合类   42篇
一般理论   13篇
预防医学   700篇
眼科学   132篇
药学   347篇
中国医学   11篇
肿瘤学   443篇
  2024年   10篇
  2023年   64篇
  2022年   79篇
  2021年   188篇
  2020年   115篇
  2019年   211篇
  2018年   188篇
  2017年   156篇
  2016年   176篇
  2015年   196篇
  2014年   227篇
  2013年   287篇
  2012年   437篇
  2011年   426篇
  2010年   225篇
  2009年   181篇
  2008年   344篇
  2007年   321篇
  2006年   322篇
  2005年   296篇
  2004年   272篇
  2003年   277篇
  2002年   234篇
  2001年   52篇
  2000年   31篇
  1999年   50篇
  1998年   41篇
  1997年   44篇
  1996年   20篇
  1995年   30篇
  1994年   27篇
  1993年   21篇
  1992年   25篇
  1991年   17篇
  1990年   27篇
  1989年   20篇
  1988年   8篇
  1987年   19篇
  1986年   11篇
  1984年   11篇
  1983年   13篇
  1982年   15篇
  1981年   8篇
  1980年   11篇
  1979年   12篇
  1978年   14篇
  1977年   8篇
  1970年   11篇
  1967年   11篇
  1965年   6篇
排序方式: 共有5879条查询结果,搜索用时 15 毫秒
991.
Recent reports have shown that excellent survival outcomes can be achieved in adult Burkitt’s lymphoma with the use of DA-EPOCH-R regimen. When compared to earlier intense pediatric-type protocols, this regimen is less toxic. There are limited reports available on the use of this regimen outside the context of clinical trials. We analyzed the outcomes of patients who were treated with the DA-EPOCH-R regimen [Burkitt’s lymphoma (BL), primary mediastinal B cell lymphoma (PMBCL) and HIV-positive patients with diffuse large B cell lymphoma (DLBCL)] at our center over a 3 year period. Baseline characters, responses, and toxicity data was captured from records. Event-free survival (EFS—from therapy initiation till occurrence of event (non-achievement of complete response or relapse) and overall survival (OS—from therapy initiation till death due to any cause) were estimated using Kaplan–Meier method. Among 41 patients [median age 40 years (18–76)], the following diagnoses were included-HIV negative patients (N = 29): BL (N = 24), PMBCL (N = 5); HIV positive patients (N = 12): BL (N = 8), and DLBCL (N = 4). Among those with BL, majority had stage III/IV disease (N = 21/32, 65%). At the completion of planned therapy, 33 had achieved CR (81%). One patient died due to toxicity. The actuarial EFS and OS at 2 years were 80 and 77% respectively for all patients. The OS at 2 years was 100% for PMBCL, 80% for BL and 50% for HIV-positive DLBCL. Majority of the failures in BL were in patients with advanced disease. DA-EPOCH-R can be used in real-world setting and allows treatment of older patients with BL.  相似文献   
992.
993.
994.
995.
996.

Objective

The purpose of this study was to evaluate the changes in right ventricle (RV) and left ventricle (LV) function after transcatheter atrial septal defect (ASD) closure and to assess the influence of the age and the amount of shunt.

Design

Retrospective study

Patients

Fifty‐three adult patients who underwent transcatheter closure were enrolled, then divided into subgroups according to the age (< 40 years vs ≥ 40 years), and the amount of shunt flow (QpQs < 2.5 vs QpQs ≥ 2.5).

Outcome Measures

Two‐dimensional tissue Doppler imaging was performed in a four‐chamber view at the basal ventricular septum (VS) and tricuspid valve annulus (TVA) before and at 1 month and 6 months after closure. Myocardial velocities, the myocardial performance index (MPI), and isovolumic acceleration (IVA) were assessed.

Results

At the TVA, the MPI decreased slightly and then greatly increased at 6 months after closure (P = .002). The IVA improved in all patients (P < .001), and the E′/A′ ratio decreased, especially in the old age group (P = .031) and larger shunt group (P = .035). At the VS, S′ and the IVA decreased and had not recovered until 6 months in the old age (P = .02) and larger shunt (P = .02). The Qp/Qs showed a significant reverse correlation with a decrease in the E′/A′ at the TVA (r = ?0.37, P = .008), and age of patient was correlated with a decrease in the IVA at the VS (r = ?0.32, P = .019). The age at closure (β = ?0.36, P = .002), the Qp/Qs ratio (β = ?0.45, P = .01), and RV MPI changes (β = ?7.64, P < .001) were found to be associated factors with IVA decrease at the VS.

Conclusions

After ASD closure, RV global function might be impaired. In elderly patients and patients with a large shunt, impairment of LV contractility developed until 6 months after closure. Close long‐term observation is required after closure, especially in old‐age patients with a large shunt.  相似文献   
997.
998.
Social Psychiatry and Psychiatric Epidemiology - Studies of factors affecting length of stay during psychiatric hospitalization in sub-Saharan Africa are sparse. A better understanding of such...  相似文献   
999.
Rift Valley fever virus (RVFV) poses a major threat of introduction to several continents, including North America. Such an introduction could cause significant losses to the livestock industry, in addition to substantial human morbidity and mortality. Because of the opportunistic blood host selection of Culex tarsalis mosquitoes, we hypothesized that this species could be an important bridge vector of RVFV near feedlots in the event of an introduction. We investigated the mosquito community composition at livestock feedlots and surrounding natural and residential areas to determine differences in mosquito relative abundance and blood feeding patterns attributed to cattle feeding operations. DNA extracted from abdomens of blood‐fed mosquitoes were sequenced to determine host identity. Multivariate regression analyses revealed differences between mosquito community assemblages at feedlots and non‐feedlot sites (p < 0.05), with this effect driven largely by differential abundances of Aedes vexans (padj < 0.05). Mosquito diversity was lower on feedlots than surrounding areas for three out of four feedlots. Culex tarsalis was abundant at both feedlots and nearby sites. Diverse vertebrate blood meals were detected in Cx. tarsalis at non‐feedlot sites, with a shift towards feeding on cattle at feedlots. These data support a potential for Cx. tarsalis to serve as a bridge vector of RVFV between livestock and humans in Colorado.  相似文献   
1000.
The prelisting variables essential for creating an accurate heart transplant allocation score based on survival are unknown. To identify these we studied mortality of adults on the active heart transplant waiting list in the Scientific Registry of Transplant Recipients database from January 1, 2004 to August 31, 2015. There were 33 069 candidates awaiting heart transplantation: 7681 UNOS Status 1A, 13 027 Status 1B, and 12 361 Status 2. During a median waitlist follow‐up of 4.3 months, 5514 candidates died. Variables of importance for waitlist mortality were identified by machine learning using Random Survival Forests. Strong correlates predicting survival were estimated glomerular filtration rate (eGFR), serum albumin, extracorporeal membrane oxygenation, ventricular assist device, mechanical ventilation, peak oxygen capacity, hemodynamics, inotrope support, and type of heart disease with less predictive variables including antiarrhythmic agents, history of stroke, vascular disease, prior malignancy, and prior tobacco use. Complex interactions were identified such as an additive risk in mortality based on renal function and serum albumin, and sex‐differences in mortality when eGFR >40 mL/min/1.73 m. Most predictive variables for waitlist mortality are in the current tiered allocation system except for eGFR and serum albumin which have an additive risk and complex interactions.  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