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   12506篇
  免费   778篇
  国内免费   37篇
耳鼻咽喉   112篇
儿科学   291篇
妇产科学   173篇
基础医学   1696篇
口腔科学   270篇
临床医学   1680篇
内科学   2756篇
皮肤病学   118篇
神经病学   1058篇
特种医学   535篇
外科学   1558篇
综合类   61篇
一般理论   4篇
预防医学   1045篇
眼科学   132篇
药学   873篇
中国医学   14篇
肿瘤学   945篇
  2024年   11篇
  2023年   78篇
  2022年   125篇
  2021年   251篇
  2020年   183篇
  2019年   304篇
  2018年   336篇
  2017年   250篇
  2016年   294篇
  2015年   333篇
  2014年   461篇
  2013年   669篇
  2012年   1045篇
  2011年   1039篇
  2010年   598篇
  2009年   534篇
  2008年   807篇
  2007年   913篇
  2006年   815篇
  2005年   861篇
  2004年   718篇
  2003年   612篇
  2002年   640篇
  2001年   85篇
  2000年   58篇
  1999年   95篇
  1998年   155篇
  1997年   121篇
  1996年   111篇
  1995年   100篇
  1994年   83篇
  1993年   67篇
  1992年   51篇
  1991年   45篇
  1990年   36篇
  1989年   41篇
  1988年   31篇
  1987年   14篇
  1986年   17篇
  1985年   30篇
  1984年   28篇
  1983年   33篇
  1982年   35篇
  1981年   21篇
  1980年   23篇
  1978年   13篇
  1977年   13篇
  1975年   14篇
  1974年   10篇
  1970年   10篇
排序方式: 共有10000条查询结果,搜索用时 937 毫秒
991.

Aim

To investigate characteristics and outcome among patients suffering in-hospital cardiac arrest (IHCA) with the emphasis on gender and age.

Methods

Using the Swedish Register of Cardiopulmonary Resuscitation, we analyzed associations between gender, age and co-morbidities, etiology, management, 30-day survival and cerebral function among survivors in 14,933 cases of IHCA. Age was divided into three ordered categories: young (18–49 years), middle-aged (50–64 years) and older (65 years and above). Comparisons between men and women were age adjusted.

Results

The mean age was 72.7 years and women were significantly older than men. Renal dysfunction was the most prevalent co-morbidity. Myocardial infarction/ischemia was the most common condition preceding IHCA, with men having 27% higher odds of having MI as the underlying etiology. A shockable rhythm was found in 31.8% of patients, with men having 52% higher odds of being found in VT/VF. After adjusting for various confounders, it was found that men had a 10% lower chance than women of surviving to 30 days. Older individuals were managed less aggressively than younger patients. Increasing age was associated with lower 30-day survival but not with poorer cerebral function among survivors.

Conclusion

When adjusting for various confounders, it was found that men had a 10% lower chance than women of surviving to 30 days after in-hospital cardiac arrest. Older individuals were managed less aggressively than younger patients, despite a lower chance of survival. Higher age was, however, not associated with poorer cerebral function among survivors.  相似文献   
992.

Background Context

In Lenke 1C and 2C curves, the choice between selective thoracic fusion (STF) versus non-selective thoracic fusion as the optimal surgical treatment is controversial.

Objective

This study aimed to assess the radiological and clinical outcome of patients with Lenke 1C and 2C curves treated with STF.

Study Design

This is a retrospective study.

Patient Sample

A total of 44 patients comprised the study sample.

Methods

Forty-four patients with Lenke 1C and 2C curves with adolescent idiopathic scoliosis who underwent STF were reviewed. Radiological parameters and Scoliosis Research Society (SRS)-22r scores were assessed preoperatively, postoperatively, and on final follow-up. The incidence of coronal decompensation, lumbar decompensation, and adding-on phenomenon were reported.

Results

Mean follow-up duration was 45.1±12.3 months and mean age was 17.0±5.1 years. The preoperative middle thoracic and thoracolumbar/lumbar (MT:TL/L) Cobb angle ratio was 1.4±0.3 and the MT:TL/L apical vertebra translation (AVT) ratio was 1.6±0.8. Final follow-up coronal balance was ?13.0±11.5?mm, main thoracic AVT was 6.9±11.8?mm, and lumbar AVT was ?20.4±13.8?mm (p<.05). Lumbar Cobb angle improved from 47.5°±7.8° to 24.9°±8.2° after operation and 23.3°±9.8° at final follow-up. The spontaneous lumbar curve correction rate was 50.9%. There were 9 patients (20.5%) who had coronal decompensation, 4 patients (9.1%) who had lumbar decompensation, and 11 patients (25.0%) who had adding-on phenomenon. We did not perform any revision surgery. The SRS-22r scores improved significantly in the overall scores, self-image, and mental health domain.

Conclusions

Selective thoracic fusion led to improvement in the radiological and clinical outcome for patients with Lenke 1C and 2C. Although no patients required revision surgery, the rate of coronal decompensation, lumbar decompensation, and adding-on phenomenon are significant.  相似文献   
993.
In this study, a tetracycline-regulated lentiviral vector system, based on the tetracycline-dependent transactivator rtTA2(S)-M2, was developed for controlled expression of glial cell line-derived neurotrophic factor (GDNF) in the rat brain. Expression of the marker gene green fluorescent protein (GFP) and GDNF was tightly regulated in a dose-dependent manner in neural cell lines in vitro. Injection of high-titer lentiviral vectors into the rat striatum resulted in a 7-fold induction of GDNF tissue levels (1060 pg/mg tissue), when doxycycline (a tetracycline analog) was added to the drinking water. However, low levels of GDNF (150 pg/mg tissue) were also detected in animals that did not receive doxycycline, indicating a significant background leakage from the vector system in vivo. The level of basal expression was markedly reduced when a 10-fold lower dose of the tetracycline-regulated GDNF vector was injected into the striatum (3-11 pg/mg tissue), and doxycycline-induced GDNF tissue levels obtained in these animals were about 190 pg/mg tissue. Doxycycline-induced expression of GDNF resulted in a significant downregulation of the tyrosine hydroxylase (TH) protein in the intact striatum. Removal of doxycycline from the drinking water rapidly (within 3 days) turned off transgenic GDNF mRNA expression and GDNF protein levels in the tissue were completely reduced by 2 weeks, demonstrating the dynamics of the system in vivo. Accordingly, TH protein expression returned to normal by 2-8 weeks after removal of doxycycline, indicating that GDNF-induced downregulation of TH is a reversible event.  相似文献   
994.
The current high spatial and temporal resolution, multi-slice imaging capability, and ECG-gated reconstruction of multi-slice computed tomography (MSCT) allows the non-invasive 3D imaging of opacified coronary arteries. MSCT coronary angiography studies are currently carried out by the visual inspection of the degree of stenosis and it has been shown that the assessment with sensitivities and specificities of 90% and higher can be achieved. To increase the reproducibility of the analysis, we present a method that performs the quantitative analysis of coronary artery diseases with limited user interaction: only the positioning of one or two seed points is required. The method allows the segmentation of the entire left or right coronary tree by the positioning of a single seed point, and an extensive evaluation of a particular vessel segment by placing a proximal and distal seed point. The presented method consists of: (1) the segmentation of the coronary vessels, (2) the extraction of the vessel centerline, (3) the reformatting of the image volume, (4) a combination of longitudinal and transversal contour detection, and (5) the quantification of vessel morphological parameters. The method is illustrated in this paper by the segmentation of the left and right coronary trees and by the analysis of a coronary artery segment. The sensitivity of the positioning of the seed points is studied by varying the position of the proximal and distal seed points with a standard deviation of 6 and 8 mm (along the vessels course) respectively. It is shown that only close to the individual seed points the vessel centerlines deviate and that for more than 80% of the centerlines the paths coincide. Since the quantification depends on the determination of the centerline, no user variability is expected as long as the seed points are positioned reasonably far away from the vessel lesion. The major bottleneck of MSCT imaging of the coronary arteries is the potential lack of image quality due to limitations in the spatial and temporal resolution, irregular or high heart beat, respiratory effects, and variations of the distribution of the contrast agent: the number of rejected vessel segments in diagnostic studies is currently still too high for implementation in routine clinical practice. Also for the automated quantitative analysis of the coronary arteries high image quality is required. However, based upon the trend in technological development of MSCT scanners, there is no doubt that the quantitative analysis of MSCT coronary angiography will benefit from these technological advances in the near future.  相似文献   
995.
996.
Purpose: To explore perceptions of balance and falls among people with mild to moderate Parkinson’s disease 3???12?months following participation in supervised balance training.

Materials and methods: This qualitative study used in-depth individual interviews for data collection among 13 people with Parkinson’s disease. Interviews were systematically analyzed using qualitative content analysis with an inductive approach.

Results: Three main themes arose: Falls – avoided and intended highlights the wide spectrum of fall perceptions, ranging from worse-case scenario to undramatized events; Balance identity incorporates how gradual deterioration in balance served as a reminder of disease progression and how identifying themselves as “aware not afraid” helped certain participants to maintain balance confidence despite everyday activity restriction; Training as treatment recounts how participants used exercise as disease self-management with the aim to maintain independence in daily life. Interpretation of the underlying patterns of these main themes resulted in the overarching theme Training as treatment when battling problems with balance and falls.

Conclusions: Whereas certain participants expressed a fear of falling which they managed by activity restriction, others described being confident in their balance despite avoidance of balance-challenging activities. Training was used as treatment to self-manage disease-related balance impairments in order to maintain independence in daily life.

  • Implication for Rehabilitation
  • People with Parkinson’s disease require early advice about the positive effects of physical activity as well as strategies for self-management in order to ease the psychological and physical burden of progressive balance impairment.

  • Fear of falling should be investigated alongside activity avoidance in this group in order to provide a more accurate insight into the scope of psychological concerns regarding balance and falls in everyday life.

  • Certain people with Parkinson’s disease define their balance according to activities they continue to participate in, while others who express fear-related activity avoidance require help to adapt balance-challenging activities in order to maintain balance confidence and avoid physical inactivity.

  相似文献   
997.
998.
999.
1000.
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