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   793篇
  免费   38篇
  国内免费   19篇
耳鼻咽喉   2篇
儿科学   14篇
妇产科学   3篇
基础医学   64篇
口腔科学   5篇
临床医学   71篇
内科学   210篇
皮肤病学   3篇
神经病学   6篇
特种医学   44篇
外科学   295篇
综合类   16篇
预防医学   11篇
眼科学   2篇
药学   34篇
肿瘤学   70篇
  2022年   3篇
  2021年   5篇
  2018年   6篇
  2017年   3篇
  2016年   6篇
  2015年   5篇
  2014年   6篇
  2013年   8篇
  2012年   9篇
  2011年   5篇
  2010年   14篇
  2009年   16篇
  2008年   16篇
  2007年   33篇
  2006年   23篇
  2005年   13篇
  2004年   21篇
  2003年   18篇
  2002年   28篇
  2001年   42篇
  2000年   48篇
  1999年   58篇
  1998年   35篇
  1997年   39篇
  1996年   33篇
  1995年   21篇
  1994年   29篇
  1993年   8篇
  1992年   15篇
  1991年   25篇
  1990年   23篇
  1989年   36篇
  1988年   22篇
  1987年   27篇
  1986年   27篇
  1985年   25篇
  1984年   12篇
  1983年   5篇
  1982年   9篇
  1981年   8篇
  1980年   9篇
  1979年   7篇
  1978年   5篇
  1976年   4篇
  1975年   5篇
  1974年   6篇
  1972年   4篇
  1971年   3篇
  1967年   2篇
  1880年   2篇
排序方式: 共有850条查询结果,搜索用时 15 毫秒
21.
牛津膝置换是使用最广泛的膝关节单髁置换(UKR)。牛津膝在37年前开始应用,拥有一个全匹配的活动衬垫,因而磨损率非常低。牛津膝最主要的使用指征是膝关节前内侧骨关节炎,这种病人至少占所有需要行膝关节置换术患者的50%。由于这一系统的设计特点,传统UKR的反指征,如年龄、活动量、肥胖、髌股关节损害和软骨钙质沉着症等对于牛津膝均不是反指征。与全膝关节置换(TKR)相比,牛津膝提供更快的康复、更好的功能、更大的活动度和更好的术后满意度,发生并发症更少、程度更轻,病残率和死亡率更低。一个持续超过30年的研究显示在90%的病例中,牛津膝为患者终生提供了优或良的临床结果,且不需要翻修。在最近15年,牛津膝通过微创手术入路植入,涉及6000多例使用该入路牛津膝置换的9个研究报道显示,10年生存率约95%。在许多这样的研究中,医生们在拟行膝关节置换的患者中约50%使用了牛津单髁膝置换。  相似文献   
22.
Thirty-two rats had truncal vagotomy either with or without pyloroplasty. After 2 or 4 weeks, respectively, the pancreas was excised and weighed. Measurements of amylase, trypsin, lipase, total protein, and DNA were obtained from the homogenated pancreatic tissue. Isolated pancreatic lobules were incubated with and without ceruletide (5 X 10(-10) g/ml) during a 60 minute period. Amylase values were determined four times in the incubation medium. Morphometry was performed by light microscopy analysis. There was a significant increase in pancreatic weight, DNA content, and trypsin concentration 2 weeks after vagotomy with and without pyloroplasty. These changes were accelerated after 4 weeks. DNA, amylase, and total protein concentrations were unchanged. Lipase concentration decreased 2 weeks after vagotomy and pyloroplasty, whereas at 4 weeks, it decreased in both experimental groups. The in vitro incubation study revealed a significantly decreased amylase discharge under basal conditions, whereas the stimulated amylase discharge was unchanged in both experimental groups compared with the control group. Morphometry did not detect differences in exocrine cellular size. We conclude that vagotomy in rats induces pancreatic hyperplasia, enzyme dissociation, and decreased basal amylase discharge in vitro.  相似文献   
23.
Objective: The authors performed a prospective evaluation of staging laparoscopy with laparoscopic ultrasonography in predicting surgical resectability in patients with carcinomas of the pancreatic head and periampullary region.Summary Background Data: Pancreatic resection with curative intent is possible in a select minority of patients who have carcinomas of the pancreatic head and periampullary region. Patient selection is important to plan appropriate therapy and avoid unnecessary laparotomy in patients with unresectable disease. Laparoscopic ultrasonography is a novel technique that combines the proven benefits of staging laparoscopy with high resolution intraoperative ultrasound of the liver and pancreas, but which has yet to be evaluated critically in the staging of pancreatic malignancy.Methods: A cohort of 40 consecutive patients referred to a tertiary referral center and with a diagnosis of potentially resectable pancreatic or periampullary cancer underwent staging laparoscopy with laparoscopic ultrasonography. The diagnostic accuracy of staging laparoscopy alone and in conjunction with laparoscopic ultrasonography was evaluated in predicting tumor resectability (absence of peritoneal or liver metastases; absence of malignant regional lymphadenopathy; tumor confined to pancreatic head or periampullary region).Results: “Occult” metastatic lesions were demonstrated by staging laparoscopy in 14 patients (35%). Laparoscopic ultrasonography demonstrated factors confirming unresectable tumor in 23 patients (59%), provided staging information in addition to that of laparoscopy alone in 20 patients (53%), and changed the decision regarding tumor resectability in 10 patients (25%). Staging laparoscopy with laparoscopic ultrasonography was more specific and accurate in predicting tumor resectability than laparoscopy alone (88% and 89% versus 50% and 65%, respectively).Conclusions: Staging laparoscopy is indispensable in the detection of “occult” intraabdominal metastases. Laparoscopic ultrasonography improves the accuracy of laparoscopic staging in patients with potentially resectable pancreatic and periampullary carcinomas.  相似文献   
24.
This in vitro study investigates the interaction between aggregation substance (AS), a virulence factor of Enterococcus faecalis, and colonic mucosal fibronectin in normal colon and colon from patients with Crohn's disease. Fibronectin was found to be overexpressed in Crohn's disease compared to normal colon. Compared to E. faecalis OG1X:pAM944 (AS-negative), E. faecalis OG1X:pAM721 (expressing AS) showed a significantly enhanced adhesion to human colonic mucosa in normal colon and in colon from patients with Crohn's disease. Double-staining of fibronectin and AS-positive enterococci showed that colocalization of bacteria and fibronectin was significantly more frequent in Crohn's disease than in normal colon. Preincubation of bacteria with soluble fibronectin caused a significant reduction in the adherence to fibronectin. In conclusion, the interaction between AS and fibronectin plays is an important factor that mediates adhesion of Enterococcus faecalis to colonic mucosa. This might be one of the mechanisms responsible for bacterial translocation of Enterococcus faecalis.  相似文献   
25.
SUMMARY This double-blind, randomised, cross-over study investigated the antihypertensive efficacy of ramipril and enalapril was completed by 30 patients with mild-to-moderate essential hypertension. After a four-week placebo run-in phase, the patients received either 2.5mg ramipril or 10mg enalapril once daily for four weeks. The dosages were increased to 5mg ramipril and 20mg enalapril for a further four weeks. After a placebo washout phase of four weeks, the patients were crossed over to the alternative treatment. The decrease in average 24-hour ambulatory diastolic blood pressure from week 0 to week 8 was 1.6mmHg greater with ramipril than enalapril (90% confidence interval 0.6-2.7mmHg). The corresponding reduction in for systolic blood pressure was also greater with ramipril than enalapril by 2.4mmHg (90% confidence interval: 0.5-4.2mmHg). For the difference in the drop of 24-hour ambulatory diastolic blood pressure between ramipril and enalapril the lower level of the 90% confidence interval (CI) is above the clinically relevant difference of -3mmHg. This is an indication that ramipril (2.5 and 5mg dose) is at least as effective as enalapril (10 and 20mg dose) in decreasing blood pressure in patients with mild-to-moderate essential hypertension. The duration of adequate antihypertensive effect was relatively long for both ramipril and enalapril; however, ramipril tended to have a more prolonged antihypertensive effect. Ramipril had a higher diastolic and systolic trough/peak ratio than enalapril, resulting in a more uniform antihypertensive effect over the 24-hour treatment period. Both ramipril and enalapril were well tolerated and the two treatment groups had similar safety profiles.  相似文献   
26.
A group of unique Epstein-Barr virus-containing cell lines was derived from the bone marrow of three patients with X-linked agammaglobulinemia. Efforts to obtain cell lines from the peripheral blood of these patients were uniformly unsuccessful. Immunofluorescence analyses as well as biosynthetic studies with [(35)S]methionine indicated unusual patterns of Ig synthesis in many of these bone marrow derived lines. Seven of the lines were of particular interest in that two produced no Ig of any type; two others showed no Ig by fluorescence but small amounts by [(35)S]methionine labeling; one expressed only cytoplasmic μ chains without any evidence of light chain synthesis, and two produced primarily μ chains with only slight amounts of light chains. One of the lines without membrane or cytoplasmic Ig studied in detail grew like a typical lymphoid line and was carried in intermittent culture over a period of 2 yr without Ig expression. One line grew quite differently and resembled the round cell type described previously, which has been obtained from a variety of sources. The cell line with cytoplasmic μ chains and no light-chain expression had the characteristic properties of pre-B cells. Three normal type Ig-producing cell lines also were obtained from the patients. The accumulated evidence obtained in the present study indicates that these unusual cell lines represent normal precursor cells of the B-cell lineage; these grew out in these cases because of the virtual absence of mature B cells that ordinarily overgrow the culture system. However, the possibility that in certain instances they reflect abnormal Ig synthesis characteristic of the disease has not been ruled out.  相似文献   
27.
理科大学生网络成瘾与人格特质的关系   总被引:2,自引:0,他引:2  
目的:分析理科大学生网络成瘾与其人格特质的关系。方法:于2005-09/11在上海某高校以班级为单位,对4个理科专业的220名学生进行问卷调查,4个专业分别是数学教育、计算机教育、物理师范和应用心理学。采用大学生因特网成瘾量表、交往焦虑量表、UCLA孤独量表和YG性格测验等4份问卷进行调查。大学生上网情况调查表共有52个题目,5级计分,成瘾诊断标准有耐受性、脱瘾综合症、计划性、控制性、行为特征、危害性、主观认识和行为等7个维度。按1,2,3,4,5记分,即每题填什么数记什么分,然后将各题得分相加得到维度分。判断标准:每题得1~3分转化为0分,4分转化为1分,5分转化为2分。测验每一部分导出分相加。若测验7部分中有3部分以上得分超过4分,则可基本诊断该大学生为因特网成瘾障碍患者。交往焦虑量表包含15个自陈条目,5级计分,总分从15(社交焦虑程度最低)到75(社交焦虑程度最高)。UCLA孤独量表(第3版)包含20个自陈条目,4级计分,总分从20(孤独程度最低)到80(孤独程度最高)。需要补充说明的是,交往焦虑量表是测量独立于行为的社交焦虑,UCLA孤独量表也主要是特质量表,因此这两个量表所测量的都是焦虑和孤独的人格特质而不是状态。YG性格测验问卷包含12个分量表,每个分量表有10个题目,测量一种特质。结果:共发出220份问卷,收回有效问卷211份。①成瘾者和非成瘾者在焦虑和孤独量表上的得分差异没有显著性意义。②成瘾者和非成瘾者在YG性格测验中的抑郁性、循环性、神经质、非合作性和攻击性等特质得分上,差异十分显著[(9.81±4.97),(5.95±5.10)分;(10.81±4.56),(6.78±4.46)分;(9.63±4.72),(6.51±4.67)分;(11.15±4.19),(7.28±4.43)分;(12.41±4.05),(8.69±3.69)分,均P<0.001],自卑感、主观性和细致性等特质得分上差异显著[(9.15±4.51),(6.83±4.49)分;(10.04±3.50),(7.63±4.09)分;(12.67±3.45),(10.26±4.23)分,P<0.01或P<0.05],在一般活动性、思维外向性、支配性和社会外向性等特质得分上两者没有差异。结论:理科大学生的部分人格特质和网络成瘾密切相关。  相似文献   
28.
目的:制备大鼠在体缺血再灌注模型,观察缺血预处理程序中心肌环磷酸腺苷含量及环磷酸腺苷依赖蛋白激酶活性的变化。方法:实验于2005-03/2006-10在解放军沈阳军区总医院医学实验动物中心和全军心血管研究所实验室完成。实验分组:选用健康雌性SD大鼠36只,根据预适应程序分为第1,2,3次缺血,第1,2,3次再灌注,每一时间点6只大鼠。实验过程:用手术套管法造成左冠状动脉主干缺血及再灌注。所有实验动物在实验程序结束后,取出心脏迅速置液氮保存备用。实验评估:用放射免疫法测环磷酸腺苷水平,生化法测环磷酸腺苷依赖蛋白激酶活性变化。结果:36只大鼠均进入结果分析。①环磷酸腺苷含量:第1次再灌注组低于第1次缺血组[(0.325±0.015),(0.395±0.024)pmol/g,t=6.06,P<0.001],第2次再灌注组低于第2次缺血组[(0.523±0.017),(0.708±0.067)pmol/g,t=6.56,P<0.001],第3次再灌注组低于第3次缺血组[(0.567±0.031),(0.712±0.038)pmol/g,t=7.24,P<0.001]。②环磷酸腺苷依赖蛋白激酶活性:第1次再灌注组低于第1次缺血组[(10.115±1.000),(16.351±0.849)pkat/g,t=11.12,P<0.001],第2次再灌注组低于第2次缺血组[(11.877±2.213),(14.869±0.619)pkat/g,t=3.31,P<0.01],第3次再灌注组低于第3次缺血组[(11.745±0.987),(14.766±0.329)pkat/g,t=7.09,P<0.001]。③缺血预处理程序中心肌环磷酸腺苷含量及环磷酸腺苷依赖蛋白激酶活性随缺血及再灌注呈周期性波动。在5min缺血预处理时表现为明显增高,而在间隔的再灌注程序中恰呈相反改变,有明显下降的趋势。结论:环磷酸腺苷及环磷酸腺苷依赖蛋白激酶的周期性波动变化可能是激发心肌缺血预处理的机制之一,环磷酸腺苷可能在预处理保护作用中起一些作用。  相似文献   
29.
股方肌肌骨瓣植入治疗成人股骨头缺血性坏死   总被引:1,自引:0,他引:1  
目的:目前成人股骨头缺血性坏死的手术方法较多,但远期疗效大多不肯定。股方肌肌骨瓣植入术可以治疗成人股骨头缺血性坏死,但需验证其近远期疗效。方法:选择2001-01/2007-01铜川市矿务局中心医院骨科收治的股方肌肌骨瓣植入治疗股骨头坏死患者15例(18髋),均知情同意。术中暴露股方肌及其在股骨近端的附着点,于附着点处凿取骨瓣,骨瓣为4cm×1.5cm×1.0cm的长方形,将骨瓣插入股骨头内,远端用可吸收骨钉固定。术后3,6,12,24个月门诊复查拍患髋正位和蛙式位X射线片,根据临床查体和X射线片表现将手术效果分为优、良、差3级。结果:全部患者均获随访,随访时间4~36个月。近期疗效满意,出院时疼痛症状均缓解,未见手术相关并发症。中远期随访结果优10髋,良6髋,差2髋,优良率88.9%。结论:股方肌肌骨瓣植入术治疗成人股骨头缺血性坏死近远期疗效确切,手术操作相对简单。  相似文献   
30.
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