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   3741篇
  免费   329篇
  国内免费   4篇
耳鼻咽喉   34篇
儿科学   114篇
妇产科学   84篇
基础医学   447篇
口腔科学   41篇
临床医学   470篇
内科学   662篇
皮肤病学   167篇
神经病学   302篇
特种医学   61篇
外科学   376篇
综合类   133篇
一般理论   6篇
预防医学   608篇
眼科学   37篇
药学   197篇
中国医学   3篇
肿瘤学   332篇
  2023年   16篇
  2022年   31篇
  2021年   88篇
  2020年   53篇
  2019年   98篇
  2018年   93篇
  2017年   80篇
  2016年   75篇
  2015年   100篇
  2014年   151篇
  2013年   196篇
  2012年   264篇
  2011年   261篇
  2010年   154篇
  2009年   121篇
  2008年   213篇
  2007年   250篇
  2006年   225篇
  2005年   205篇
  2004年   212篇
  2003年   184篇
  2002年   210篇
  2001年   65篇
  2000年   56篇
  1999年   25篇
  1998年   26篇
  1997年   30篇
  1996年   23篇
  1995年   25篇
  1994年   22篇
  1993年   18篇
  1992年   28篇
  1991年   53篇
  1990年   23篇
  1989年   23篇
  1988年   31篇
  1987年   28篇
  1986年   24篇
  1985年   33篇
  1984年   26篇
  1983年   24篇
  1980年   10篇
  1979年   16篇
  1978年   10篇
  1974年   14篇
  1973年   11篇
  1971年   13篇
  1970年   11篇
  1969年   14篇
  1968年   14篇
排序方式: 共有4074条查询结果,搜索用时 15 毫秒
71.
Abstract

The first and second year students in the Faculty of Medicine were surveyed concerning their attitudes toward informing a person that his or her illness was likely to be terminal if the person in question were the student, a parent, or a member of the general public. Attitudes were overwhelmingly in favor of direct truth telling, especially in the second year group. The possible influence of the first year course in Behavioral Sciences is considered.  相似文献   
72.
73.
74.
Erosion by flowing fluids carves striking landforms on Earth and also provides important clues to the past and present environments of other worlds. In these processes, solid boundaries both influence and are shaped by the surrounding fluid, but the emergence of morphology as a result of this interaction is not well understood. We study the coevolution of shape and flow in the context of erodible bodies molded from clay and immersed in a fast, unidirectional water flow. Although commonly viewed as a smoothing process, we find that erosion sculpts pointed and cornerlike features that persist as the solid shrinks. We explain these observations using flow visualization and a fluid mechanical model in which the surface shear stress dictates the rate of material removal. Experiments and simulations show that this interaction ultimately leads to self-similarly receding boundaries and a unique front surface characterized by nearly uniform shear stress. This tendency toward conformity of stress offers a principle for understanding erosion in more complex geometries and flows, such as those present in nature.  相似文献   
75.
Prostate cancer (PCa) and benign prostatic hyperplasia (BPH) are androgen-dependent diseases commonly treated by inhibiting androgen action. However, androgen ablation or castration fail to target androgen-independent cells implicated in disease etiology and recurrence. Mechanistically different to castration, this study shows beneficial proapoptotic actions of estrogen receptor–β (ERβ) in BPH and PCa. ERβ agonist induces apoptosis in prostatic stromal, luminal and castrate-resistant basal epithelial cells of estrogen-deficient aromatase knock-out mice. This occurs via extrinsic (caspase-8) pathways, without reducing serum hormones, and perturbs the regenerative capacity of the epithelium. TNFα knock-out mice fail to respond to ERβ agonist, demonstrating the requirement for TNFα signaling. In human tissues, ERβ agonist induces apoptosis in stroma and epithelium of xenografted BPH specimens, including in the CD133+ enriched putative stem/progenitor cells isolated from BPH-1 cells in vitro. In PCa, ERβ causes apoptosis in Gleason Grade 7 xenografted tissues and androgen-independent cells lines (PC3 and DU145) via caspase-8. These data provide evidence of the beneficial effects of ERβ agonist on epithelium and stroma of BPH, as well as androgen-independent tumor cells implicated in recurrent disease. Our data are indicative of the therapeutic potential of ERβ agonist for treatment of PCa and/or BPH with or without androgen withdrawal.  相似文献   
76.
Pediatric SOT recipients are medically fragile and present with complex care issues requiring high‐level management at home. Parents of hospitalized children have reported inadequate preparation for discharge, resulting in problems transitioning from hospital to home and independently self‐managing their child's complex care needs. The aim of this study was to investigate factors associated with the transition from hospital to home and chronic illness care for parents of heart, kidney, liver, lung, or multivisceral recipients. Fifty‐one parents from five pediatric transplant centers completed questionnaires on the day of hospital discharge and telephone interviews at three wk, three months, and six months following discharge from the hospital. Care coordination (p = 0.02) and quality of discharge teaching (p < 0.01) was significantly associated with parent readiness for discharge. Readiness for hospital discharge was subsequently significantly associated with post‐discharge coping difficulty (p = 0.02) at three wk, adherence with medication administration (p = 0.03) at three months, and post‐discharge coping difficulty (p = 0.04) and family management (p = 0.02) at six months post‐discharge. The results underscore the important aspect of education and care coordination in preparing patients and families to successfully self‐manage after hospital discharge. Assessing parental readiness for hospital discharge is another critical component for identifying risk of difficulties in managing post‐discharge care.  相似文献   
77.
Within the Paracanoeing discipline, it is important to ensure that appropriate control is achieved by a paddler with a disability. However, this Paralympic Games discipline has seen very little attention to date. The aims of this study were to understand the kinematic impact to a paracanoeist when not utilizing the use of a prosthetic lower-limb. A kayaker with a uni-lateral transfemoral amputation completed several 200?m maximal efforts both with and without their prosthesis. When the prosthetic limb was removed, there were significant differences found in stroke rate, stroke speed, stroke length and overall power output. Sagittal and frontal video analysis demonstrated the residual limb movements when paddling and indicated where support would be required to improve the kayak’s control. It is recommended that those with lower-limb absence wishing to paddle a kayak competitively utilize the use of a prostheses designed for the kayaking environment that supports the residual limb at both the upper and inner thigh and the distal end.
  • Implications for rehabilitation
  • This paper is the first study to investigate both biomechanical and assistive technology-related issues in the new Paralympic Games sport of Paracanoeing.

  • For participants possessing lower-limb absence, a prosthetic limb that is designed specifically for the kayaking environment is recommended when Paracanoeing to maximize efficient propulsion.

  • Use of an ergometer and multiple 2D cameras provides practitioners the ability to optimize both the comfort and fit of a prosthetic limb.

  • Use of an ergometer and multiple 2D cameras provides both athletes and practitioners the ability to optimize the points of human contact within a kayak to ensure comfort and control.

  相似文献   
78.

Background

It has recently been suggested that myocardial oedema follows a bimodal pattern early post ST-segment elevation myocardial infarction (STEMI). Yet, water content, quantified using tissue desiccation, did not return to normal values unlike oedema quantified by cardiovascular magnetic resonance (CMR) imaging. We studied the temporal changes in the extent and intensity of injured myocardium using T1-mapping technique within the first week after STEMI.

Methods

A first group (n?=?31) underwent 3 acute 3?T CMR scans (time-point (TP) <?3?h, 24?h and 6?days), including cine, native shortened modified look-locker inversion recovery T1 mapping, T2* mapping and late gadolinium enhancement (LGE). A second group (n?=?17) had a single scan at 24?h with an additional T2-weighted sequence to assess the difference in the extent of area-at-risk (AAR) compared to T1-mapping.

Results

The mean T1 relaxation time value within the AAR of the first group was reduced after 24?h (P?<?0.001 for TP1 vs.TP2) and subsequently increased at 6?days (P?=?0.041 for TP2 vs.TP3). However, the extent of AAR quantified using T1-mapping did not follow the same course, and no change was detected between TP1&TP2 (P?=?1.0) but was between TP2 &TP3 (P?=?0.019). In the second group, the extent of AAR was significantly larger on T1-mapping compared to T2-weighted (42?±?15% vs. 39?±?15%, P?=?0.025). No change in LGE was detected while microvascular obstruction and intra-myocardial haemorrhage peaked at different time points within the first week of reperfusion.

Conclusion

The intensity of oedema post-STEMI followed a bimodal pattern; while the extent of AAR did not track the same course. This discrepancy has implications for use of CMR in this context and may explain the previously reported disagreement between oedema quantified by imaging and tissue desiccation.
  相似文献   
79.
The “winner's curse” is a subtle and difficult problem in interpretation of genetic association, in which association estimates from large‐scale gene detection studies are larger in magnitude than those from subsequent replication studies. This is practically important because use of a biased estimate from the original study will yield an underestimate of sample size requirements for replication, leaving the investigators with an underpowered study. Motivated by investigation of the genetics of type 1 diabetes complications in a longitudinal cohort of participants in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Genetics Study, we apply a bootstrap resampling method in analysis of time to nephropathy under a Cox proportional hazards model, examining 1,213 single‐nucleotide polymorphisms (SNPs) in 201 candidate genes custom genotyped in 1,361 white probands. Among 15 top‐ranked SNPs, bias reduction in log hazard ratio estimates ranges from 43.1% to 80.5%. In simulation studies based on the observed DCCT/EDIC genotype data, genome‐wide bootstrap estimates for false‐positive SNPs and for true‐positive SNPs with low‐to‐moderate power are closer to the true values than uncorrected naïve estimates, but tend to overcorrect SNPs with high power. This bias‐reduction technique is generally applicable for complex trait studies including quantitative, binary, and time‐to‐event traits.  相似文献   
80.

Objective

To identify important sources of distress among burn survivors at discharge and 6, 12, and 24 months postinjury, and to examine if the distress related to these sources changed over time.

Design

Exploratory.

Setting

Outpatient burn clinics in 4 sites across the country.

Participants

Participants who met preestablished criteria for having a major burn injury (N=1009) were enrolled in this multisite study.

Interventions

Participants were given a previously developed list of 12 sources of distress among burn survivors and asked to rate on a 10-point Likert-type scale (0=no distress to 10=high distress) how much distress each of the 12 issues was causing them at the time of each follow-up.

Main Outcomes Measures

The Medical Outcomes Study 12-Item Short-Form Health Survey was administered at each time point as a measure of health-related quality of life. The Satisfaction With Appearance Scale was used to understand the relation between sources of distress and body image. Finally, whether a person returned to work was used to determine the effect of sources of distress on returning to employment.

Results

It was encouraging that no symptoms were worsening at 2 years. However, financial concerns and long recovery time are 2 of the highest means at all time points. Pain and sleep disturbance had the biggest effect on ability to return to work.

Conclusions

These findings can be used to inform burn-specific interventions and to give survivors an understanding of the temporal trajectory for various causes of distress. In particular, it appears that interventions targeted at sleep disturbance and high pain levels can potentially effect distress over financial concerns by allowing a person to return to work more quickly.  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