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   39636篇
  免费   3355篇
  国内免费   1585篇
耳鼻咽喉   379篇
儿科学   522篇
妇产科学   451篇
基础医学   6224篇
口腔科学   3204篇
临床医学   5244篇
内科学   4860篇
皮肤病学   734篇
神经病学   1912篇
特种医学   2443篇
外国民族医学   8篇
外科学   5667篇
综合类   5033篇
现状与发展   11篇
一般理论   1篇
预防医学   1259篇
眼科学   563篇
药学   2552篇
  12篇
中国医学   1261篇
肿瘤学   2236篇
  2024年   119篇
  2023年   670篇
  2022年   1104篇
  2021年   1425篇
  2020年   1486篇
  2019年   1424篇
  2018年   1427篇
  2017年   1356篇
  2016年   1341篇
  2015年   1419篇
  2014年   2518篇
  2013年   3411篇
  2012年   2157篇
  2011年   2499篇
  2010年   1883篇
  2009年   1994篇
  2008年   2025篇
  2007年   2064篇
  2006年   1822篇
  2005年   1670篇
  2004年   1448篇
  2003年   1293篇
  2002年   943篇
  2001年   857篇
  2000年   632篇
  1999年   599篇
  1998年   477篇
  1997年   467篇
  1996年   414篇
  1995年   356篇
  1994年   319篇
  1993年   245篇
  1992年   257篇
  1991年   250篇
  1990年   207篇
  1989年   188篇
  1988年   186篇
  1987年   166篇
  1986年   140篇
  1985年   190篇
  1984年   152篇
  1983年   112篇
  1982年   141篇
  1981年   151篇
  1980年   123篇
  1979年   90篇
  1978年   73篇
  1977年   58篇
  1976年   78篇
  1975年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
BACKGROUND: Moderate hypothermia is one of the effective therapeutic methods for head injury in recent years, there are many mechanisms of moderate hypothermia for brain protection, and its influence on cerebral oxygenation is also one of them. OBJECTIVE: To observe the influence of moderate hypothermia on cerebral oxygenation of animals with acute intracranial hypertension, and further investigate the protective mechanism of moderate hypothermia. DESIGN: A randomized controlled trial. SETTING: Department of Neurosurgery, Renji Hospital affiliated to the Medical College of Shanghai Jiao Tong University. MATERIALS: Twenty healthy little pigs, either male or female, weighing 4.5–5.5 kg, were used. Neurotrend-typed multiparameter monitoring system (Diametrics Company, British); CMA/100 micro-injection pump (Carnegie Company, Sweden). METHODS: The experiment was conducted in the Changzheng Hospital affiliated to the Second Military Medical University of Chinese PLA in November, 2001. The pigs were randomized into two groups: the normothermia group (control group, n =10) and moderate hypothermia group (n =10). ① Bilateral femoral arteries were separated, one was connected to pressometer for monitoring mean arterial pressure (MEP), and the other for analysis of blood gases [including peripheral blood pH value, arterial partial pressure of carbon dioxide (PaCO2), arterial partial pressure of carbon dioxide (PaCO2), HCO3–]. ② Rectal temperature was monitored with mercurial thermometer. ③ Intracranial pressure was monitored using Camino optic ICP probe placed in the subdural space. ④ Neurotrend multiparameter monitoring sensor was inserted into the white matter for about 4 cm to determine cerebral perfusion pressure (CPP, CPP=MAP(ICP), brain tissue partial oxygen pressure (PO2), partial pressure of carbon dioxide (PCO2), HCO3– and brain temperature. The rectal temperature of animals in the moderate hypothermia group was lowered to 34 ℃ using ice bags, and the body temperature was maintained at 33–35 ℃ for 2 hours. The changes of the parameters were observed continuously, and the pigs in the normothermia group were not treated with cooling. MAIN OUTCOME MEASURES: ① MAP, ICP, rectal temperature, CCP; Indexes of cerebral oxygenation detected with Neurotrend-typed multiparameter monitoring system; ② Results of blood gases analysis in the moderate hypothermia group. RESULTS: All the 20 pigs were involved in the analysis of results. ① MAP, ICP, rectal temperature, CCP and indexes of cerebral oxygenation: In the moderate hypothermia group, the ICP after cooling was obviously lower than that before cooling [(3.31±1.19), (5.33±0.95) kPa, P < 0.05], CCP was higher, brain tissue PCO2 [(12.03±1.73), (10.59±2.01) kPa, P < 0.05], and brain tissue pH value was higher [(7.03±1.63), (9.40±1.30) kPa, P < 0.05], whereas the brain temperature was decreased as compared with that before cooling [(34.9±0.3), (37.2±0.2) ℃, P < 0.05]. ② Results of blood gases analysis in the moderate hypothermia group: There were no significant differences in the parameters of peripheral arterial blood gases analysis before and after cooling in the moderate hypothermia group (P > 0.05) CONCLUSION: Moderate hypothermia will not impair the cerebral oxygenation, and it can reduce brain tissue CO2 and decrease brain tissue acidosis.  相似文献   
72.
73.
This paper presents a method for calculating stage line diagrams, a novel type of reference diagram useful for tracking developmental processes over time. Potential fields of applications include: dentistry (tooth eruption), oncology (tumor grading, cancer staging), virology (HIV infection and disease staging), psychology (stages of cognitive development), human development (pubertal stages) and chronic diseases (stages of dementia). Transition probabilities between successive stages are modeled as smoothly varying functions of age. Age‐conditional references are calculated from the modeled probabilities by the mid‐P value. It is possible to eliminate the influence of age by calculating standard deviation scores (SDS). The method is applied to the empirical data to produce reference charts on secondary sexual maturation. The mean of the empirical SDS in the reference population is close to zero, whereas the variance depends on age. The stage line diagram provides quick insight into both status (in SDS) and tempo (in SDS/year) of development of an individual child. Other measures (e.g. height SDS, body mass index SDS) from the same child can be added to the chart. Diagrams for sexual maturation are available as a web application at http://vps.stefvanbuuren.nl/puberty . The stage line diagram expresses status and tempo of discrete changes on a continuous scale. Wider application of these measures scores opens up new analytic possibilities. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
74.
面颊部扩张皮瓣的设计和转移   总被引:7,自引:0,他引:7  
目的探讨利用扩张皮瓣修复面颊不同部位皮肤缺损的扩张皮瓣设计。方法269例面颊部血管瘤、瘢痕、色素痣患者,依不同的皮肤缺损位置,在邻近部位放置大小适度的1~3个50~400ml容积的扩张器,扩张充分后采用推进皮瓣法、旋转推进皮瓣法和易位皮瓣法修复。结果269例中共形成305个扩张皮瓣,利用推进皮瓣121个,旋转推进皮瓣145个,易位皮瓣39个;共出现并发症52例,分别为扩张皮瓣远端血运障碍、血肿形成、感染、注水壶渗漏、扩张器外露、睑外翻和包囊挛缩,这些并发症基本未影响最终的手术效果,术后面颊部形态正常。结论我们提出的扩张皮瓣的设计和转移原则,对于面颊部的皮肤缺损组织扩张术治疗有非常重要的参考价值。  相似文献   
75.
封闭式负压引流治疗软组织感染   总被引:3,自引:0,他引:3  
目的探讨封闭式负压引流治疗软组织感染的疗效。方法应用封闭式负压引流治疗开放性骨折发生软组织感染18例。结果18例均获随访,时间6个月-1年6个月。软组织感染均愈合,骨折正常愈合12例,延迟愈合6例,无慢性骨感染发生。结论封闭式负压引流治疗软组织感染,可短期控制感染,为进一步治疗创造条件,尤其适用于深部软组织感染患者。手术简单,疗效可靠,适合基层医院应用。  相似文献   
76.
目的应用重组人骨形态发生蛋白4基因腺相关病毒载体(AAV-hBMP4)转染兔骨髓基质干细胞(BMSCs),观察其对BMSCs生物学行为的影响,从而为骨组织工程寻找理想的病毒载体及种子细胞。方法全骨髓法培养兔BMSCs,按感染复数(MOI)值不同设定为四组,分别转染兔BMSCs,观察病毒量对细胞形态的影响。选取影响最小的MOI值,进行后续实验。转染兔BMSCs,MTT法描记细胞生长曲线,观察AAV对细胞增殖活性的影响。以重组增强型绿色荧光蛋白基因的腺相关病毒载体(AAV-EGFP)为参照,行流式细胞仪检测,计算转染效率。AAV-hBMP4与对照病毒AAV-EGFP分别转染细胞,观察细胞形态,行碱性磷酸酶(ALP)染色、Von Kossa染色及ALP含量测定,观察成骨活性。兔肌袋实验观察异位成骨情况。结果MOI值为5×10~4 vg/cell时,AAV对细胞形态影响最小,以此值进行后续实验。AAV转染后,细胞增殖活性良好,转染效率为55%~65%。AAV-hBMP4转染后,细胞形态呈现典型的成骨改变,ALP染色及Von Kossa染色均出现成骨的特征性改变,而AAV-EGFP组无上述改变。细胞上清ALP含量测定显示,实验组ALP含量显著增高,与对照组比较差异有统计学意义(t=218.65,P<0.01)。兔肌袋实验术后4周组织学检测可见大量钙盐沉积,矿化结节形成。结论AAV-hBMP4转染效率高,对BMSCs的增殖活性影响小,AAV-hBMP4转染的BMSCs可望成为组织工程化骨的理想种子细胞。  相似文献   
77.
Conjugated linoleic acid (CLA) is a unique lipid that elicits dramatic reductions in adiposity in several animal models when included at < or = 1% of the diet. Despite a flurry of investigations, the precise mechanisms by which conjugated linoleic acid elicits its dramatic effects in adipose tissue and liver are still largely unknown. In vivo and in vitro analyses of physiological modifications imparted by conjugated linoleic acid on protein and gene expression suggest that conjugated linoleic acid exerts its de-lipidating effects by modulating energy expenditure, apoptosis, fatty acid oxidation, lipolysis, stromal vascular cell differentiation and lipogenesis. The purpose of this review shall be to examine the recent advances and insights into conjugated linoleic acid's effects on obesity and lipid metabolism, specifically focused on changes in gene expression and physiology of liver and adipose tissue.  相似文献   
78.
目的:观察胶原蛋白海绵在皮肤扩张术中的临床应用效果。方法:选择40例(个)皮肤扩张器埋置和50例(个)皮肤扩张器取出及15例自身对照的病例组,应用胶原蛋白海绵术中贴敷于渗血创面,术后观察其吸收、止血效果。结果:术中渗血于2~10min内停止,病例组中无血肿发生,术后引流量明显减少,伤口愈合时间缩短。结论:在皮肤扩张术中胶原蛋白海绵是一种良好的生物止血材料。  相似文献   
79.
计算机辅助手术和治疗(IGST)是一个新兴的多学科交叉的研究领域,近年来取得了飞速的发展.作为该领域顶级会议之一的国际计算机辅助放射学及手术大会(CARS2003)于2003年6月25至28日在英国伦敦伊丽莎白二世国际会议中心隆重举行了第17届会议.本文将对这次大会作一回顾和总结,内容包括科学论文方面的评论和产品展览方面的情况.  相似文献   
80.
孟康  吕树铮  蔡春辉 《中国医药》2009,4(8):564-566
目的明确Angiomemor(美国Simbionix公司生产)血管介入仿真模拟器是否有助于冠状动脉造影技术的掌握和提高。方法选取16名无血管放射介入经验的心血管医生,接受相同课时的冠状动脉介入造影理论培训后,按随机表编码随机分为模拟器培训组与非培训组各8名,模拟器培训组8名医生接受Angiomemor血管介入仿真模拟器培训,模拟冠状动脉造影操作,非培训组8名心血管医生未接受仿真模拟器培训。在随后的真实临床环境中操作冠状动脉造影时,评价2组医生冠状动脉造影操作过程中错误的频数、平均造影时间、造影剂使用量及术中放射线剂量。结果相对于非培训组,模拟器培训组医生在冠状动脉造影操作中错误频数减少62.5%、平均造影时间减少44.0%、造影剂使用量减少44.0%,术中平均放射线曝光时间减少了57.7%,平均X线累计曝光剂量减少51.6%,单位面积X线累计曝光剂量减少了52.4%。结论Angiomemor血管介入仿真模拟器有助于医生较快地熟练掌握冠状动脉造影技术,是冠状动脉介入规范化培训的重要辅助手段之一。  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