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   1876篇
  免费   294篇
  国内免费   39篇
耳鼻咽喉   18篇
儿科学   106篇
妇产科学   28篇
基础医学   99篇
口腔科学   26篇
临床医学   292篇
内科学   624篇
皮肤病学   61篇
神经病学   176篇
特种医学   316篇
外科学   232篇
综合类   35篇
预防医学   58篇
眼科学   16篇
药学   60篇
中国医学   1篇
肿瘤学   61篇
  2024年   9篇
  2023年   52篇
  2022年   13篇
  2021年   29篇
  2020年   92篇
  2019年   13篇
  2018年   90篇
  2017年   72篇
  2016年   72篇
  2015年   64篇
  2014年   101篇
  2013年   116篇
  2012年   58篇
  2011年   42篇
  2010年   86篇
  2009年   116篇
  2008年   46篇
  2007年   62篇
  2006年   51篇
  2005年   37篇
  2004年   25篇
  2003年   25篇
  2002年   19篇
  2001年   39篇
  2000年   16篇
  1999年   27篇
  1998年   81篇
  1997年   96篇
  1996年   78篇
  1995年   68篇
  1994年   52篇
  1993年   52篇
  1992年   27篇
  1991年   15篇
  1990年   28篇
  1989年   55篇
  1988年   43篇
  1987年   28篇
  1986年   22篇
  1985年   20篇
  1984年   21篇
  1983年   12篇
  1982年   17篇
  1981年   14篇
  1980年   16篇
  1979年   12篇
  1978年   8篇
  1977年   9篇
  1976年   10篇
  1971年   8篇
排序方式: 共有2209条查询结果,搜索用时 0 毫秒
91.
We present a case of type B aortic dissection with a rare aortic arch branching variation whereby two separate brachiocephalic trunks arise from the arch. This case also highlights the potential implications of this variant in the management of thoracic aortic dissections and aneurysms.  相似文献   
92.
93.

Introduction

In 2009 the Department of Health instructed McKinsey & Company to provide advice on how commissioners might achieve world class National Health Service productivity. Asymptomatic inguinal hernia repair was identified as a potentially cosmetic procedure, with limited clinical benefit. The Birmingham and Solihull primary care trust cluster introduced a policy of watchful waiting for asymptomatic inguinal hernia, which was implemented across the health economy in December 2010. This retrospective cohort study aimed to examine the effect of a change in clinical commissioning policy concerning elective surgical repair of asymptomatic inguinal hernias.

Methods

A total of 1,032 patients undergoing inguinal hernia repair in the 16 months after the policy change were compared with 978 patients in the 16 months before. The main outcome measure was relative proportion of emergency repair in groups before and after the policy change. Multivariate binary logistic regression was used to adjust the main outcome for age, sex and hernia type.

Results

The period after the policy change was associated with 59% higher odds of emergency repair (3.6% vs 5.5%, adjusted odds ratio [OR]: 1.59, 95% confidence interval [CI]: 1.03–2.47). In turn, emergency repair was associated with higher odds of adverse events (4.7% vs 18.5%, adjusted OR: 3.68, 95% CI: 2.04–6.63) and mortality (0.1% vs 5.4%, p<0.001, Fisher’s exact test).

Conclusions

Introduction of a watchful waiting policy for asymptomatic inguinal hernias was associated with a significant increase in need for emergency repair, which was in turn associated with an increased risk of adverse events. Current policies may be placing patients at risk.  相似文献   
94.
95.
96.
97.
98.
The precise mechanisms regulating T-helper function have been intensively investigated. We and others have recently identified a new T-cell-B-cell-activating molecule called T-BAM that directs B-cell differentiation by interacting with the CD40 molecule on B cells. Using a specific monoclonal antibody against T-BAM (5C8), we have previously shown that T-BAM expressing T cells are predominantly CD4+CD8- and in normal lymphoid tissue have a unique distribution. However, no information has been obtained regarding the phenotype and functional properties of human neoplastic T cells. Therefore, we investigated T- BAM expression immunohistochemically in 87 well-characterized T-cell non-Hodgkin's lymphomas and lymphoid leukemias (LL). We found that 21/81 neoplasms expressed detectable T-BAM and these positive tumors belong almost exclusively to the CD4+CD8- subtype. In addition, to determine whether T-BAM expression could be induced on T-BAM-LL cells, we activated T-BAM-LLs in vitro and showed that T-BAM could be upregulated only in CD4+CD8- tumors. Our studies clearly show that T- BAM is constitutively expressed in a large number of T-cell neoplasms with a relative mature phenotype (CD4+CD8-) and that only CD4+ neoplastic T cells can be induced in vitro to express this molecule. Additional studies are necessary to identify the biologic significance of T-BAM expression and its potential and clinical implications.  相似文献   
99.
Bowen-Pope  DF; Malpass  TW; Foster  DM; Ross  R 《Blood》1984,64(2):458-469
Platelet-derived growth factor (PDGF) is a potent mitogen for many cultured connective tissue cells. It is present in concentrated form within the platelet alpha-granules and is believed to be released during platelet degranulation at sites of vascular injury. We have used a sensitive radioreceptor assay to measure PDGF levels in whole blood serum from normal humans [17.5 +/- 3.1 (SD) ng/mL] and baboons (2.7 +/- 1.2 ng/mL). PDGF was not detected in plasma from either species. In addition, plasma was found to substantially reduce the ability of added purified PDGF to bind to the cell surface PDGF receptor on cultured cells, suggesting that plasma may contain a PDGF-binding protein that would serve to inactivate PDGF released into plasma. Calculations of PDGF concentrations in serum have been corrected for the effects of the binding protein. 125I-PDGF injected intravenously into normal baboons was cleared rapidly from the plasma (t1/2 = two minutes). The rapid clearance of 125I-PDGF did not result from iodination damage, as purified unlabeled PDGF was cleared with comparable kinetics. The rapid clearance of purified and iodinated PDGF did not result from changes in PDGF structure during purification or from removal of PDGF-associated proteins during purification, as PDGF present in freeze-thaw lysates of fresh platelets was cleared equally rapidly. We conclude that release of PDGF at sites of vascular injury would greatly increase the local concentration of PDGF and that PDGF not localized to the site of injury would be rapidly cleared from the circulation.  相似文献   
100.

Introduction

Knowledge of patterns of blood use in the care of mass casualty settings is important for preparedness of medical centre resources and for maximising survival when blood supplies are limited. Our objectives were to review of our experience with the use of blood products and define the utilisation of blood transfusion following suicide bombing attacks.

Patients and methods

We conducted a retrospective analysis of blood and blood product transfusion following civilian bombing attacks at a level I trauma centre in Jerusalem, Israel from 2000 to 2005. The study group consisted of 137 patients who were admitted following 17 suicide bombing attacks which were carried out in Jerusalem during the 5-year period. Demographic data, number of units of blood and blood products transfused and the need for massive transfusions were recorded and analyzed.

Results

Fifty-three patients received blood transfusions (38.7%). There were 33 males (62.2%) with a median ISS of 13 (range 4–25). These 53 patients received 524 PRBC, 42 WB, and 449 FFP. The mean number of PRBC transfused/admitted patient was 3.82 units (range 0–59). Thirty patients (21.9%) received 236 PRBC (45% of total PRBC) at the first 2 h. The ratio of ordered to transfused blood was 946:524. The FFP:PRBC ratio for all transfused patients was 1:1.17. The number of PRBC transfused per attack correlated with the number of patients admitted per attack. The most commonly transfused blood type was A (52.3%). Only 18 units of uncrossed-matched blood were transfused (3.3% of total). 14 patients (10.2%) received massive transfusions. These patients received 399 PRBC (76.1% of total units transfused) and the average number of PRBC transfused was 28.5/patient (10–59).

Conclusions

More than 1/3 of casualties admitted following civilian bombing attacks received transfusions, most in the first 2 h. Large-scale attacks will require more blood and blood products than small-scale attacks. Twice the number of PRBC ordered than transfused reflects a known trend for over-triage during the initial assessment following bombing attacks. One tenth of patients received massive transfusion.  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