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   2871452篇
  免费   201075篇
  国内免费   5321篇
耳鼻咽喉   40657篇
儿科学   95337篇
妇产科学   81224篇
基础医学   411455篇
口腔科学   81902篇
临床医学   254649篇
内科学   548958篇
皮肤病学   63650篇
神经病学   223169篇
特种医学   112340篇
外国民族医学   841篇
外科学   436814篇
综合类   62739篇
现状与发展   2篇
一般理论   882篇
预防医学   214473篇
眼科学   66635篇
药学   218937篇
  10篇
中国医学   6114篇
肿瘤学   157060篇
  2018年   28853篇
  2016年   25246篇
  2015年   28404篇
  2014年   39069篇
  2013年   59201篇
  2012年   79965篇
  2011年   85476篇
  2010年   50877篇
  2009年   47560篇
  2008年   80899篇
  2007年   86783篇
  2006年   88053篇
  2005年   85053篇
  2004年   82111篇
  2003年   79400篇
  2002年   77103篇
  2001年   135345篇
  2000年   138934篇
  1999年   117016篇
  1998年   32420篇
  1997年   28765篇
  1996年   28754篇
  1995年   27339篇
  1994年   25448篇
  1993年   23722篇
  1992年   92764篇
  1991年   90461篇
  1990年   89425篇
  1989年   86472篇
  1988年   79322篇
  1987年   78289篇
  1986年   74003篇
  1985年   70677篇
  1984年   52571篇
  1983年   44950篇
  1982年   26220篇
  1981年   23337篇
  1979年   48833篇
  1978年   34175篇
  1977年   29773篇
  1976年   27486篇
  1975年   30052篇
  1974年   35632篇
  1973年   34517篇
  1972年   32547篇
  1971年   30476篇
  1970年   28216篇
  1969年   27072篇
  1968年   24917篇
  1967年   22242篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.

Introduction

Malignant pleural mesothelioma (MPM) is an uncommon cancer with a poor prognosis and heterogeneous survival. Surgery for MPM is offered in some specialist centers to highly selected patients. A previously described classification and regression tree (CART) model stratified survival in unselected MPM patients using routinely collected clinical data. This study aimed to examine the performance of this CART model on a highly selected surgical population.

Methods

Data were collected from subjects undergoing cytoreductive surgery for MPM from specialist centers in Hyõgo, Japan, and Sydney, Australia, between 1991 and 2016. The CART model was applied using the combination of clinical variables to stratify subjects into risk groups (1 through 4); survival characteristics were then compared.

Results

Two hundred eighty-nine cases were included (205 from Australia, 84 from Japan). Overall median survival was 34.6 (interquartile range: 17.5–56.1) months; median age was 63.0 (interquartile range: 57.0–67.8) years, and 83.0% (n = 240) were male. There were no clinically meaningful differences between the two cohorts. Survival across the four risk groups was significantly different (p < 0.0001); the model stratified survival well with a Harrell's concordance statistic of 0.62 (95% confidence interval: 0.57–0.66) at 36 months. The group with the longest survival (median, 82.5 months) had: no weight loss, hemoglobin > 153 g/L and serum albumin > 43 g/L at time of referral to the surgical center.

Conclusions

Using routinely available clinical variables, the CART model was able to stratify surgical patients into risk groups with statistically different survival characteristics with fair to good performance. Presence of weight loss, anemia, and low albumin should confer caution when considering surgical therapy for MPM.  相似文献   
102.
Abstract

Background

Across the spectrum of patient care for opioid overdose, an important, yet frequently overlooked feature is the bystander, or witness to the overdose event. For other acute medical events such as cardiac arrest and stroke, research supports that the presence of a bystander is associated with better outcomes. Despite the similarities, however, this well-established conceptual framework has yet to be applied in the context of overdose patient outcomes. The objective of this study was to assess the association between the nature of the bystander-patient relationship and prehospital care measures in patients being treated for opioid overdose.  相似文献   
103.
locStra is an ‐package for the analysis of regional and global population stratification in whole‐genome sequencing (WGS) studies, where regional stratification refers to the substructure defined by the loci in a particular region on the genome. Population substructure can be assessed based on the genetic covariance matrix, the genomic relationship matrix, and the unweighted/weighted genetic Jaccard similarity matrix. Using a sliding window approach, the regional similarity matrices are compared with the global ones, based on user‐defined window sizes and metrics, for example, the correlation between regional and global eigenvectors. An algorithm for the specification of the window size is provided. As the implementation fully exploits sparse matrix algebra and is written in C++, the analysis is highly efficient. Even on single cores, for realistic study sizes (several thousand subjects, several million rare variants per subject), the runtime for the genome‐wide computation of all regional similarity matrices does typically not exceed one hour, enabling an unprecedented investigation of regional stratification across the entire genome. The package is applied to three WGS studies, illustrating the varying patterns of regional substructure across the genome and its beneficial effects on association testing.  相似文献   
104.
Visceral fat loss in response to four‐cycle ergometer training regimens with explicit differences in exercise intensity and modality was compared. Fifty‐nine obese young women (body fat percentage ≥ 30%) were randomized to a 12‐week intervention consisting of either all‐out sprint interval training (SITall‐out, n = 11); supramaximal SIT (SIT120, 120% O2peak, n = 12); high‐intensity interval training (HIIT90, 90% O2peak, n = 12), moderate‐intensity continuous training (MICT, 60% O2peak, n = 11), or no training (CON, n = 13). The total work done per training session in SIT120, HIIT90, and MICT was confined to 200 kJ, while it was deliberately lower in SITall‐out. The abdominal visceral fat area (AVFA) was measured through computed tomography scans. The whole‐body and regional fat mass were assessed through dual‐energy X‐ray absorptiometry. Pre‐, post‐, and 3‐hour post‐exercise serum growth hormone (GH), and epinephrine (EPI) were measured during selected training sessions. Following the intervention, similar reductions in whole‐body and regional fat mass were found in all intervention groups, while the reductions in AVFA resulting from SITall‐out, SIT120, and HIIT90 (>15 cm2) were greater in comparison with MICT (<3.5 cm2, P < .05). The AVFA reductions among the SITs and HIIT groups were similar, and it was concomitant with the similar exercise‐induced releases of serum GH and EPI. CON variables were unchanged. These findings suggest that visceral fat loss induced by interval training at or above 90% O2peak appeared unresponsive to the change in training intensity. Nonetheless, SITall‐out is still the most time‐efficient strategy among the four exercise‐training regimes for controlling visceral obesity.  相似文献   
105.
106.
107.
108.
The present study enumerates the attenuating effects of curcumin and α-tocopherol against propoxur induced oxidative DNA damage in human peripheral blood mononuclear cells (PBMC). Cultured cells were isolated from peripheral blood of healthy volunteers, and were exposed to varying concentrations of propoxur (0–21?μg/ml) for 6, 12, and 24?h, and in combination with curcumin (9.2?μg/ml) or α-tocopherol (4.3?μg/ml) or both. Cytotoxic effect of propoxur was examined by MTT assay. The role of oxidative stress beneath the cytotoxicity of propoxur was evaluated by the measurement of reduced glutathione (GSH), malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OH-dG) levels in cell lysate. A concentration-dependent cell death, depletion of GSH, an increase in the level of both MDA and 8-OH-dG were observed. Co-treatment with curcumin or α-tocopherol significantly attenuates depleted GSH, decrease in MDA and 8-OH-dG levels in propoxur exposed cells (p?相似文献   
109.
110.
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