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   7722篇
  免费   669篇
  国内免费   22篇
耳鼻咽喉   79篇
儿科学   222篇
妇产科学   240篇
基础医学   1070篇
口腔科学   97篇
临床医学   982篇
内科学   1560篇
皮肤病学   153篇
神经病学   802篇
特种医学   217篇
外科学   1088篇
综合类   198篇
一般理论   6篇
预防医学   824篇
眼科学   83篇
药学   367篇
中国医学   4篇
肿瘤学   421篇
  2023年   80篇
  2022年   118篇
  2021年   246篇
  2020年   142篇
  2019年   242篇
  2018年   247篇
  2017年   164篇
  2016年   194篇
  2015年   202篇
  2014年   315篇
  2013年   363篇
  2012年   511篇
  2011年   514篇
  2010年   280篇
  2009年   277篇
  2008年   383篇
  2007年   421篇
  2006年   428篇
  2005年   378篇
  2004年   333篇
  2003年   280篇
  2002年   318篇
  2001年   169篇
  2000年   178篇
  1999年   139篇
  1998年   76篇
  1997年   75篇
  1996年   46篇
  1995年   54篇
  1994年   61篇
  1993年   47篇
  1992年   111篇
  1991年   94篇
  1990年   71篇
  1989年   92篇
  1988年   78篇
  1987年   73篇
  1986年   52篇
  1985年   61篇
  1984年   45篇
  1983年   44篇
  1982年   30篇
  1981年   28篇
  1980年   36篇
  1979年   41篇
  1978年   29篇
  1977年   24篇
  1974年   21篇
  1973年   22篇
  1971年   21篇
排序方式: 共有8413条查询结果,搜索用时 15 毫秒
981.
982.

Background

The factors associated with delayed gastric emptying (DGE) after a pancreaticoduodenectomy (PD) are not definitively known.

Methods

From November 2011 through to May 2012, data were prospectively collected on 711 patients undergoing a pancreaticoduodenectomy or total pancreatectomy as part of the American College of Surgeons-National Surgical Quality Improvement Program Pancreatectomy Demonstration Project. Bivariate and multivariate models were employed to determine the factors that predicted DGE.

Results

In the 711 patients, the overall rate of DGE was 20.1%. In a bivariate analysis, intra-operative factors such as pylorus-preservation (47.1% versus 43.7%, P = 0.40), intra-operative drain placement (85.5%, versus 85.1%, P = 0.91) and an antecolic compared with a retrocolic gastrojejunostomy (60.1% versus 65.1%, P = 0.26) were not different between the DGE and no DGE groups. Pancreatic fistula formation (31.2% versus 10.1%), post-operative sepsis (21.7% versus 7.0%), organ space surgical site infection (SSI) (23.9% versus 7.9%), need for percutaneous drainage (23.0% versus 10.6%) and reoperation (10.6% versus 3.1%) were higher in patients with DGE (P < 0.0001). In a multivariable model, only pancreatic fistula, post-operative sepsis and reoperation were independently associated with DGE.

Discussion

In this multicentre study, only post-operative complications were associated with DGE. Neither pylorus preservation nor route of enteric reconstruction (antecolic versus retrocolic) was associated with delayed gastric emptying.  相似文献   
983.
984.

Purpose

Attempts to understand the causes of cognitive impairment in obstructive sleep apnea (OSA) are complicated by the overlap among clinical and demographic factors that may impact cognition. The goal of the current study was to isolate the contribution of hypoxemia to cognitive impairment in OSA.

Methods

Two groups of 20 patients with newly diagnosed OSA were compared. The groups differed on severity of hypoxemia but not other demographic (e.g., age, gender, education, estimated premorbid IQ) or clinical (e.g., sleep related respiratory disturbances, daytime sleepiness, depressive symptoms) variables. Participants completed polysonmography and cognitive assessment.

Results

We compared patients with high and low hypoxemia on measures of memory, attention, executive functioning, and motor coordination using independent sample t-tests. The high hypoxemia group performed significantly better on immediate recall (Hopkins Verbal Learning Test — Revised; t?=??2.50, p?<?0.02) than the low hypoxemia group. No group differences were observed on other neuropsychological measures.

Conclusions

This study is one of the first to compare the cognitive performance of patients with high and low hypoxemia after controlling for demographic factors and aspects of OSA severity that could confound the relationship. In our carefully matched sample, we observed an unexpected advantage of higher hypoxemia on memory. These preliminary findings are discussed in the context of basic science literature on the protective effects of adaptation to intermittent hypoxemia. Our data suggest that the association between hypoxemia and cognition may not straightforward. Future research targeting the effects of hypoxemia on cognition controlling for other clinical factors in large groups of patients with OSA will be important.  相似文献   
985.
986.
Mental health policy in Australia is committed to the development of recovery‐focused services and facilitating consumer participation in all aspects of mental health service delivery. Negative attitudes of mental health professionals have been identified as a major barrier to achieving these goals. Although the education of health professionals has been identified as a major strategy, there is limited evidence to suggest that consumers are actively involved in this education process. The aim of this qualitative study was to evaluate students’ views and opinions at having been taught ‘recovery in mental health nursing’ by a person with a lived experience of significant mental health challenges. In‐depth interviews were held with 12 students. Two main themes were identified: (i) ‘looking through fresh eyes’ – what it means to have a mental illness; and (ii) ‘it's all about the teaching’. The experience was perceived positively; students referred to the impact made on their attitudes and self‐awareness, and their ability to appreciate the impact of mental illness on the individual person. Being taught by a person with lived experience was considered integral to the process. This innovative approach could enhance consumer participation and recovery‐focused care.  相似文献   
987.
Haiti has the lowest improved water and sanitation coverage in the Western Hemisphere and is suffering from the largest cholera epidemic on record. In May of 2012, an assessment was conducted in rural areas of the Artibonite Department to describe the type and quality of water sources and determine knowledge, access, and use of household water treatment products to inform future programs. It was conducted after emergency response was scaled back but before longer-term water, sanitation, and hygiene activities were initiated. The household survey and source water quality analysis documented low access to safe water, with only 42.3% of households using an improved drinking water source. One-half (50.9%) of the improved water sources tested positive for Escherichia coli. Of households with water to test, 12.7% had positive chlorine residual. The assessment reinforces the identified need for major investments in safe water and sanitation infrastructure and the importance of household water treatment to improve access to safe water in the near term.  相似文献   
988.

Aims/hypothesis

HNF1A-MODY is a monogenic form of diabetes caused by mutations in the HNF1A gene. Here we identify, for the first time, HNF1A-MODY-associated microRNAs (miRNAs) that can be detected in the serum of HNF1A-MODY carriers.

Methods

An miRNA array was carried out in rat INS-1 insulinoma cells inducibly expressing the common human Pro291fsinsC-HNF1A frame shift mutation. Differentially expressed miRNAs were validated by quantitative real-time PCR. Expression of miRNAs in the serum of HNF1A-MODY carriers (n?=?31), MODY-negative family members (n?=?10) and individuals with type 2 diabetes mellitus (n?=?17) was quantified by absolute real-time PCR analysis.

Results

Inducible expression of Pro291fsinsC-HNF1A in INS-1 cells caused a significant upregulation of three miRNAs (miR-103, miR-224, miR-292-3p). The differential expression of two miRNAs (miR-103 and miR-224) was validated in vitro. Strongly elevated levels of miR-103 and miR-224 could be detected in the serum of HNF1A-MODY carriers compared with MODY-negative family controls. Serum levels of miR-103 distinguished HNF1A-MODY carriers from HbA1c-matched individuals with type 2 diabetes mellitus.

Conclusions/interpretation

Our study demonstrates that the pathophysiology of HNF1A-MODY is associated with the overexpression of miR-103 and miR-224. Furthermore, our study demonstrates that these miRNAs can be readily detected in the serum of HNF1A-MODY carriers.  相似文献   
989.

Objective

The binding of abatacept (CTLA‐4Ig) to the B7 ligands CD80 and CD86 prevents the engagement of CD28 on T cells and thereby prevents effector T cell activation. In addition, a direct effect of CTLA‐4Ig on antigen‐presenting cells (APCs) could contribute to the therapeutic effect. To further elucidate the mechanism of CTLA‐4Ig, we performed phenotype and functional analyses of APCs in patients with rheumatoid arthritis (RA) before and after the initiation of CTLA‐4Ig therapy.

Methods

Peripheral blood mononuclear cells were analyzed before and at 2 and 4 weeks after the initiation of CTLA‐4Ig therapy. Proportions of APCs were determined by flow cytometry. CD14+ monocytes were further analyzed for the expression of costimulatory and adhesion molecules and for their transendothelial migratory capacity in vitro. In addition, CD14+ monocytes from healthy controls were analyzed for their migratory and spreading capacity.

Results

Proportions and absolute numbers of monocytes were significantly increased in RA patients treated with CTLA‐4Ig. The expression of several adhesion molecules was significantly diminished. In addition, monocytes displayed a significant reduction in their endothelial adhesion and transendothelial migratory capacity upon treatment with CTLA‐4Ig. Likewise, isolated monocytes from healthy controls revealed a significant reduction in their migratory and spreading activity after preincubation with CTLA‐4Ig or anti‐CD80 and anti‐CD86 antibodies.

Conclusion

We describe direct effects of CTLA‐4Ig therapy on phenotype and functional characteristics of monocytes in RA patients that might interfere with the migration of monocytes to the synovial tissue. This additional mechanism of CTLA‐4Ig might contribute to the beneficial effects of CTLA‐4Ig treatment in RA patients.
  相似文献   
990.

Background

The rehabilitation of older patients in Ireland after an acute medical event occurs at dedicated onsite hospital units or at offsite centres. Information on medical complications and outcomes is inadequate.

Aims

Enumeration of medical complications of patients admitted to a dedicated onsite rehabilitation unit for older people, and the extent of co-morbidity in the population with the effects that this had on the evolution of medical complications.

Methods

A retrospective analysis of patients admitted to a 58-bed onsite unit over a 1-year period was performed. Information collating co-morbidities, medical complications and functional outcomes was recorded.

Results

Medical complications occurred in almost 95 % of patients, where full data were available. Over one-third required intravenous therapy.

Conclusion

Twenty-four hour medical cover is required for older patients managed at onsite rehabilitation units. Further studies on offsite medical rehabilitation facilities for older patients are required.  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