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   36585篇
  免费   3802篇
  国内免费   733篇
耳鼻咽喉   121篇
儿科学   4494篇
妇产科学   3380篇
基础医学   3098篇
口腔科学   400篇
临床医学   4059篇
内科学   4279篇
皮肤病学   197篇
神经病学   1778篇
特种医学   913篇
外国民族医学   4篇
外科学   2588篇
综合类   3950篇
现状与发展   2篇
一般理论   5篇
预防医学   6305篇
眼科学   690篇
药学   2991篇
  21篇
中国医学   907篇
肿瘤学   938篇
  2024年   82篇
  2023年   684篇
  2022年   849篇
  2021年   1662篇
  2020年   1467篇
  2019年   1696篇
  2018年   1560篇
  2017年   1629篇
  2016年   1588篇
  2015年   1446篇
  2014年   2426篇
  2013年   3057篇
  2012年   2001篇
  2011年   2248篇
  2010年   1754篇
  2009年   1661篇
  2008年   1677篇
  2007年   1621篇
  2006年   1403篇
  2005年   1234篇
  2004年   1047篇
  2003年   949篇
  2002年   740篇
  2001年   679篇
  2000年   535篇
  1999年   469篇
  1998年   440篇
  1997年   392篇
  1996年   365篇
  1995年   283篇
  1994年   312篇
  1993年   258篇
  1992年   238篇
  1991年   221篇
  1990年   193篇
  1989年   174篇
  1988年   175篇
  1987年   145篇
  1986年   153篇
  1985年   227篇
  1984年   206篇
  1983年   172篇
  1982年   162篇
  1981年   150篇
  1980年   140篇
  1979年   105篇
  1978年   85篇
  1977年   68篇
  1976年   66篇
  1975年   47篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
女性减肥者的体像问题与社会支持及性格的关系   总被引:7,自引:0,他引:7  
目的研究女性减肥者的体像特征及相关因素。方法采用体像障碍自评量表、社会支持量表、艾森克个性问卷调查了100例减肥门诊女性就诊者,并与100例近5年无减肥经历女性对照。结果(1)女性减肥者,体像得分明显高于正常对照组。(2)女性减肥者的体像得分与收入、P分、N分明显正相关;与社会支持得分明显负相关,与BMI无相关性。结论女性减肥者,不管是否为单纯性肥胖,都存在较多的体像问题,且与特定得人格和社会支持有关。  相似文献   
72.
目的:为了探讨非依赖型糖尿病全血低切变率粘度值测定的临床意义。方法:对91例非依赖型糖尿病血液流变学低切率粘度值进行了检测,并对其结果及形成机制进行了分析讨论。结果:91例非依赖型糖尿病低切变率粘度值和对照组相比有显著性差异,p<0.01。结论:非依赖型糖尿病全血低切变率粘度增高,可造成微血管循环障碍,是非依赖型糖尿病易形成心梗、脑梗及其他微血管病的一种重要因素。  相似文献   
73.
弧形切割吻合器在低位直肠癌超低位前切除术中的应用   总被引:1,自引:0,他引:1  
目的总结弧形切割吻合器在低位直肠癌超低位前切除术中的应用价值。方法2005年12月至2006年9月选择56例低位直肠癌患者在全直肠系膜切除和侧方淋巴结清扫的基础上,应用弧形切割吻合器对直肠(肛管)残端进行切割、闭合,用33mm管型吻合器进行超低位结肠-直肠(肛管)吻合术。结果56例低位直肠癌患者术中没有发生切割和闭合不全的病例,吻合口无渗漏。手术后住院时间为(11.2±3.2)d,无死亡者。发生吻合口瘘2例(3.6%),经过局部引流而自然愈合1例,因直肠阴道瘘进行横结肠造口转流1例,无吻合口狭窄。结论弧形切割吻合器在低位直肠癌超低位前切除术中具有切割完整、闭合确实、吻合口瘘发生率低的优点,有良好的应用推广价值。  相似文献   
74.
目的 探讨如何选择合适的保肛手术方法治疗低位直肠癌。方法 44例肿块下缘距肛缘5~7cm的低位直肠癌患者,对21例采用改良的结肠肛管吻合术(A组)、23例应用吻合器技术的前切除术(B组)进行治疗;并对两组疗效予以对比。结果 A组患者无远端直肠残端肿瘤残留,B组有2例。肿瘤远端直肠切除距离A组平均为(2.81±0.35)cm,B组(1.73±0.42)cm。两组比较,差异有显著性意义(t=9.083,P<0.001)。A组术后两年均无吻合口复发,B组有4例,B组吻合口复发率明显高于A组(x~2=4.234,P=0.04)。A组术后早期排便功能较差,但均能在半年内改善;B组术后排便功能良好。结论 低位直肠癌患者肿瘤下缘距肛缘5~7cm、肿瘤“T”分期为Ⅱ、Ⅲ期、术前指诊肿瘤可推动、肿瘤侵犯肠壁范围不到1周可行保肛手术。应根据患者体型、骨盆宽窄、肿瘤分化程度及其侵犯肠管的周径合理选择改良的结肠肛管吻合术或吻合器技术的前切除术。  相似文献   
75.
The aim of the study was to assess if lung function at birth predicts lung function at 2 yr and secondly, if lung function development was influenced by the common phenotypes of recurrent bronchial obstruction (rBO) or atopic eczema (AE) by 2 yr. Lung function was assessed at birth (n = 802) and at 2 yr within the prospective birth cohort study 'the Environment and Childhood Asthma Study' in Oslo. The 135 children with lung function measured at birth by tidal flow volume (TFV) loops and passive respiratory mechanics, who were included in a nested case-control study were reinvestigated at 2 yr with clinical examination, TFV loops (n = 90) (mean age 26.6 (3.7 s.d.) months), skin prick test and parental interview. Children were categorized into quartiles (lower, middle two, upper) according to time to peak tidal expiratory flow/total expiratory time (t(PTEF)/t(E)) at birth as well as clinical phenotype based on the presence of rBO and/or AE (ever) by 2 yr. The observed reduction in mean t(PTEF)/t(E) from birth to 2 yr within the quartiles, were not significantly different after controlling for 'regression to the mean'. t(PTEF)/t(E) at birth correlated significantly with t(PTEF)/t(E) at 2 yr, (r = 0.475, p < 0.001). Children with both rBO and AE by 2 yr had significantly lower t(PTEF)/t(E) at 2 yr (p = 0.002) and at birth (p = 0.027), compared with children with no rBO or AE. Clinical phenotype at 2 yr did not influence the change in t(PTEF)/t(E) from birth to 2 yr. This study demonstrates a clear tracking of lung function from birth, not influenced by rBO or AE by 2 yr.  相似文献   
76.
How many subjects are needed in a longitudinal birth cohort study?   总被引:8,自引:8,他引:0  
One of the first decisions that needs to be taken when planning a birth cohort concerns the size of the study. This in turn will depend on the research questions to be answered and thence whether environmental exposures and outcomes are measured on a continuum or as dichotomous variables. Here we describe ways in which different birth cohorts have addressed this issue and explore the advantages of smaller detailed studies over larger less-detailed studies.  相似文献   
77.
辛伐他汀对人低密度脂蛋白氧化修饰影响的实验研究   总被引:2,自引:2,他引:0  
目的研究辛伐他汀在体外对低密度脂蛋白氧化修饰的影响.方法以低密度脂蛋白氧化修饰为模型,以硫代巴比妥酸反应物质(TBARS)生成量及相对电泳迁移率(REM)为指标,研究了辛伐他汀对铜离子(Cu2 )诱导低密度脂蛋白氧化修饰的抑制作用.结果随辛伐他汀浓度从1~10μmol/L的增加,TBARS值分别减少67.3%,73.9%,81.9%,REM值减少48.3%,55.2%,58.6%,呈浓度及时间依赖关系.其中10μmol/L辛伐他汀可几乎完全抑制低密度脂蛋白氧化.结论辛伐他汀在体外能明显抑制Cu2 诱导的低密度脂蛋白氧化修饰.  相似文献   
78.
目的 :探讨影响双胎妊娠临床结局的相关因素。方法 :回顾性分析 12 8例双胎妊娠临床结局与胎方位、分娩方式、孕周、新生儿体重、新生儿窒息之间的关系。 结果 :胎方位、孕周、胎儿体重及分娩方式均影响围产儿预后。 结论 :加强孕产期保健 ,提高产科质量能改善双胎妊娠围产儿的预后。  相似文献   
79.
BACKGROUND: Low molecular weight heparins (LMWH) like dalteparin are increasingly used for anticoagulation during haemodialysis (HD). The available laboratory tests for monitoring LMWH anticoagulation are time-consuming and expensive, and the suitability of the conventional activated clotting time (ACT) is controversial. A simple and cheap bedside test would be useful. METHODS: We studied the factor Xa-activated whole blood clotting time (Xa-ACT) in vitro and in vivo in nine patients undergoing chronic HD with i.v. dalteparin bolus anticoagulation and compared it with the conventional ACT. Plasma anti-factor Xa (antiXa) activity was determined with a chromogenic assay. Thrombin-antithrombin complexes were measured to detect coagulation activation. RESULTS: Xa-ACT and ACT were prolonged with rising dalteparin concentration. In vitro, both clotting times were strongly correlated with the antiXa levels (r = 0.94 and 0.89, respectively). Nevertheless, compared with the ACT, the Xa-ACT was considerably more sensitive to the LMWH in vitro (healthy blood: Xa-ACT 90 s/U vs ACT 26 s/U; uraemic blood: Xa-ACT 96 s/U vs ACT 31 s/U) as well as in vivo (Xa-ACT 81 s/U vs ACT 22 s/U) and reflected different intensities of anticoagulation. An initial dalteparin bolus of 80+/-11 U/kg body weight was able to prevent coagulation activation for up to 4 h of HD. CONCLUSION: For monitoring LMWH anticoagulation the Xa-ACT was superior to the conventional ACT in vitro as well as in vivo during HD. The Xa-ACT can be useful as a LMWH bedside test. The ACT was not sensitive enough to serve as a LMWH monitoring tool.  相似文献   
80.
The aim of this study was to clarify and compare the temporal course of bone mineral density (BMD) between fast bone losers and normal residents in Miyama Village, a rural Japanese community. BMD was measured over a 10-year period in a cohort study in Miyama Village, Wakayama Prefecture, Japan, to provide information on rate of bone loss in the mature and elderly population. Subjects (n=400) were selected by sex and age stratum from the full list of residents born in 1910–1949, with 50 men and 50 women in each age decade. Baseline BMD of the lumbar spine and proximal femur was measured using dual energy X-ray absorptiometry in 1990, 1993, 1997 and 2000. In the cohort, 171 men and 189 women completed the follow-up survey performed in 1993. After calculating the rate of bone loss between 1990 and 1993, the greatest tertile from the distribution of bone loss was categorized as fast bone losers, with the remainder considered as normal subjects. Changes in BMD were compared between normal subjects and fast bone losers over the 10-year period. Mean rate of change for BMD at both lumbar spine and femoral neck in fast bone losers recovered to levels similar to those in normal subjects over 7 years of observation. By contrast, BMD at the lumbar spine and femoral neck decreased steeply over the 10-year period in both groups, and mean BMD for fast bone losers was significantly lower than that of normal subjects (P<0.05). These differences were apparent only at the lumbar spine in both men and women, even after adjusting for age. These results indicate that fast bone loss is a transient phenomenon rather than a fixed status, although individuals who have been categorized as fast bone losers at some stage continue to display low BMD in the lumbar spine.  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