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   16305篇
  免费   969篇
  国内免费   81篇
耳鼻咽喉   144篇
儿科学   340篇
妇产科学   250篇
基础医学   2281篇
口腔科学   356篇
临床医学   1664篇
内科学   3439篇
皮肤病学   201篇
神经病学   1748篇
特种医学   644篇
外科学   2470篇
综合类   77篇
一般理论   36篇
预防医学   1109篇
眼科学   195篇
药学   1275篇
中国医学   19篇
肿瘤学   1107篇
  2023年   103篇
  2022年   175篇
  2021年   404篇
  2020年   289篇
  2019年   435篇
  2018年   454篇
  2017年   335篇
  2016年   446篇
  2015年   432篇
  2014年   636篇
  2013年   852篇
  2012年   1227篇
  2011年   1259篇
  2010年   687篇
  2009年   637篇
  2008年   1048篇
  2007年   1123篇
  2006年   1026篇
  2005年   989篇
  2004年   878篇
  2003年   758篇
  2002年   800篇
  2001年   132篇
  2000年   82篇
  1999年   116篇
  1998年   145篇
  1997年   148篇
  1996年   129篇
  1995年   102篇
  1994年   105篇
  1993年   105篇
  1992年   80篇
  1991年   65篇
  1990年   65篇
  1989年   52篇
  1988年   45篇
  1987年   43篇
  1986年   53篇
  1985年   58篇
  1984年   50篇
  1983年   61篇
  1982年   66篇
  1981年   69篇
  1980年   65篇
  1979年   32篇
  1978年   40篇
  1977年   45篇
  1976年   33篇
  1975年   28篇
  1974年   34篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
Objective - To try out a collection of a standard set of data from computerised medical records. Design - Retrospective extraction of ordinary patient record information put into the computer by general practitioners. Setting - Encounters in office hours in strategically selected practices or health centres in Denmark, Finland, Iceland, Norway and Sweden. Subjects - 59 general practitioners and a total study population of 97475 persons. Main outcome measures - Proportions, crude and specific rates of encounters, diagnoses and processes. Results - In a 4-week period there was a threefold difference in the office encounter rates between the participating sites in the Nordic countries. Gender and age patterns were similar despite these differ ences. An access to several different denominators revealed diverse patterns of referring to the specialist, prescribing, ordering blood tests, X-rays and physiotherapy. Data from computerised medical records agree well with earlier studies in the Nordic countries using other methods. Conclusions - This survey demonstrates that valid and reliable data for routine statistics are available from computerised medical records in general practice. The major obstacle extracting more epidemiological data from computerised medical records is caused by information in the databases not being uniquely linked to episodes of care.  相似文献   
85.
86.
87.
BACKGROUND: The cytokine interleukin-4 (IL-4) is secreted mainly by activated T lymphocytes and characterizes the T-helper 2 (Th2) sub-type. In transplantation Th2 cells are believed to induce graft tolerance. Previous studies revealed that patients with a relatively high frequency of IL-4 producing helper T lymphocytes (HTL) before heart transplantation (HTX) had no or less rejection episodes compared with patients with a low frequency of IL-4 producing HTL. Three single nucleotide polymorphisms (SNPs) have been identified in the promoter region of the IL-4 gene, which influence promoter strength. We investigated whether there was a correlation between SNP genotypes in the IL-4 promoter and heart failure, and rejection after HTX. METHODS: Seventy HTX patients, 61 donors, and 36 controls were genotyped for the 3 SNPs by sequencing. RESULTS: Of the SNPs at -285 and -81, only the C and A alleles, respectively, were found in this study. Both alleles were found for the -590 SNP. No relation between patient genotype of the SNP at -590 and heart failure and rejection was found. However, incidence of rejection was significantly lower in patients that received a donor heart with the T-positive genotype compared with patients that received a heart from a T-negative donor. Patients who had the T-negative genotype and received a heart from a T-positive donor, suffered significantly less from rejection than T-negative patients that received a T-negative donor heart. This was not significant in the T-positive patient group. CONCLUSIONS: This indicates that IL-4 production within the donor heart and by cells from the donor is important for reducing incidence of episodes of rejection.  相似文献   
88.
BACKGROUND: The purpose of this study was to define risk factors that predict 30-day morbidity and mortality after gastrectomy for cancer in Veterans Affairs (VA) Medical Centers. METHODS: The VA National Surgical Quality Improvement Program prospectively collected data on 708 patients undergoing gastrectomy for cancer in 123 participating VA medical centers from 1991 to 1998. Independent variables included 68 preoperative patient characteristics and 12 intraoperative variables; the dependent variables were 21 defined adverse outcomes and death. Predictive models for 30-day morbidity and mortality were constructed by using stepwise logistic regression analysis. RESULTS: The 30-day morbidity rate was 33.3% (236 of 708). The overall 30-day mortality rate was 7.6% (54 of 708). Significant positive predictors of morbidity (P <.05) included current pneumonia, American Society of Anesthesiologists class IV (threat to life), partially dependent functional status, dyspnea on minimal exertion, preoperative transfusion, extended operative time, and increasing age. Significant positive predictors of mortality (P <.05) included do not resuscitate status, prior stroke, intraoperative transfusion, preoperative weight loss, preoperative transfusion, and elevated preoperative alkaline phosphatase level. CONCLUSIONS: Risk factors predicting morbidity and mortality rates at VA hospitals after gastrectomy for gastric cancer are reported by using a prospectively collected, multi-institutional database. Assigning relative weights to factors associated with adverse outcomes may help improve patient care.  相似文献   
89.
We compared the clinical outcome after spinal fusion between patients with isthmic spondylolisthesis and those with degenerative disc disease of the lumbar spine, using multiple logistic regression analysis. A questionnaire describing medication, pain, vocational status and patient satisfaction was mailed to all the patients at a median interval of 4 years after their operation. Fusion was evaluated on plain radiographs at a minimum of 12 months after surgery, and patients were classified as fused or not fused. The overall satisfaction rate was 70%. The results of the present study showed no difference in the outcome after spinal fusion between the two groups of patients. The factors that significantly increased the likelihood of an optimal result - defined as patient satisfaction, return to work, and reduced medication - were male gender, being in work prior to surgery, and being a non-smoker. Since spinal fusion is an expensive treatment with potentially serious risks, and leaves one-third of the patients with an unsatisfactory result, we believe that more studies focusing on the indications for surgery should be performed.  相似文献   
90.
We investigated the effects of caffeine ingestion on skeletal muscle glucose uptake, glycogen synthase (GS) activity, and insulin signaling intermediates during a 100-min euglycemic-hyperinsulinemic (100 microU/ml) clamp. On two occasions, seven men performed 1-h one-legged knee extensor exercise at 3 h before the clamp. Caffeine (5 mg/kg) or placebo was administered in a randomized, double-blind fashion 1 h before the clamp. During the clamp, whole-body glucose disposal was reduced (P < 0.05) in caffeine (37.5 +/- 3.1 micromol x min(-1) x kg(-1)) vs. placebo (54.1 +/- 2.9 micromol x min(-1) x kg(-1)). In accordance, the total area under the curve over 100 min (AUC(0--100 min)) for insulin-stimulated glucose uptake in caffeine was reduced (P < 0.05) by approximately 50% in rested and exercised muscle. Caffeine also reduced (P < 0.05) GS activity before and during insulin infusion in both legs. Exercise increased insulin sensitivity of leg glucose uptake in both caffeine and placebo. Insulin increased insulin receptor tyrosine kinase (IRTK), insulin receptor substrate 1-associated phosphatidylinositol (PI) 3-kinase activities, and Ser(473) phosphorylation of protein kinase B (PKB)/Akt significantly but similarly in rested and exercised legs. Furthermore, insulin significantly decreased glycogen synthase kinase-3alpha (GSK-3alpha) activity equally in both legs. Caffeine did not alter insulin signaling in either leg. Plasma epinephrine and muscle cAMP concentrations were increased in caffeine. We conclude that 1) caffeine impairs insulin-stimulated glucose uptake and GS activity in rested and exercised human skeletal muscle; 2) caffeine-induced impairment of insulin-stimulated muscle glucose uptake and downregulation of GS activity are not accompanied by alterations in IRTK, PI 3-kinase, PKB/Akt, or GSK-3alpha but may be associated with increases in epinephrine and intramuscular cAMP concentrations; and 3) exercise reduces the detrimental effects of caffeine on insulin action in muscle.  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