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   14560篇
  免费   1085篇
  国内免费   585篇
耳鼻咽喉   210篇
儿科学   109篇
妇产科学   80篇
基础医学   1337篇
口腔科学   344篇
临床医学   1683篇
内科学   1169篇
皮肤病学   48篇
神经病学   1437篇
特种医学   536篇
外科学   1817篇
综合类   2037篇
预防医学   1427篇
眼科学   262篇
药学   1957篇
  17篇
中国医学   1571篇
肿瘤学   189篇
  2024年   63篇
  2023年   245篇
  2022年   583篇
  2021年   696篇
  2020年   575篇
  2019年   518篇
  2018年   513篇
  2017年   506篇
  2016年   538篇
  2015年   508篇
  2014年   1010篇
  2013年   1246篇
  2012年   919篇
  2011年   955篇
  2010年   726篇
  2009年   680篇
  2008年   687篇
  2007年   674篇
  2006年   580篇
  2005年   488篇
  2004年   392篇
  2003年   388篇
  2002年   307篇
  2001年   256篇
  2000年   208篇
  1999年   189篇
  1998年   181篇
  1997年   157篇
  1996年   107篇
  1995年   127篇
  1994年   97篇
  1993年   91篇
  1992年   91篇
  1991年   76篇
  1990年   68篇
  1989年   75篇
  1988年   58篇
  1987年   66篇
  1986年   62篇
  1985年   83篇
  1984年   86篇
  1983年   85篇
  1982年   78篇
  1981年   58篇
  1980年   51篇
  1979年   25篇
  1978年   19篇
  1977年   14篇
  1976年   12篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Factors affecting choice between a managed care organization(MCO) and a fee-for-service insurance plan were examined whenthe University of Geneva health insurance plan was transformedinto an MCO, in October 1992. A case-control study using a mailedquestionnaire (response rate 84%) was conducted to compare formermembers who joined the MCO (joiners, n=421) to former memberswho opted out in order to keep fee-for-service coverage (non-joiners,n=222). Non-joiners were more likely to be women (odds ratio(OR) from multivariate model was 1.15, p=0.50), to be born inSwitzerland (OR=2.04, p<0.01), to have an annual income >75,000Swiss francs (OR=2.00, p<0.01), to have a personal physician(OR=1.96, p<0.01) and to have consulted a specialist (OR=1.69,p=0.02) or used unconventional medicine (OR=4.59, p<0.01)in the past year. During the previous year, non-joiners hadmore health care visits than joiners (14.6 versus 9.1, p=0.01).Non-joiners reported better mental health and fewer complainedof persistent fatigue (OR=2.18, p=0.03). The choice of healthplan was strongly influenced by socio-demographic characteristics,past patterns of health services utilization and health status.The self-selection process was paradoxical: MCO joiners hadused fewer health care visits than non-joiners, but their self-reportedhealth status was worse. The differences we have observed betweenself-selected populations have important implications for thefinancial performance of competing health care delivery systems.  相似文献   
32.
人心和山羊心脏上、下腔静脉肌袖大体解剖   总被引:2,自引:2,他引:0  
目的:观测人和山羊上、下腔静脉肌袖结构特点,为治疗局灶性心房颤动积累解剖学资料。方法:采用大体解剖方法观测人心(20例)和羊心(40例)的上、下腔静脉及其表面的心肌纤维。结果:人心上腔静脉肌袖的长和宽分别为(1.91±0.39)cm、(2.41±0.26)cm,下腔静脉肌袖的长和宽分别为(1.32±0.32)cm,(3.06±0.52)cm;羊心上(前)腔静脉肌袖的长和宽分别为(1.41±1.00)cm、(1.05±0.26)cm,下(后)腔静脉肌袖的长和宽分别为(0.81±0.48)cm,(1.03±0.28)cm。人和羊心脏的上腔静脉肌袖出现率均为100%;下腔静脉肌袖的出现率分别为88.89%和98%。肌纤维多数来源于右心房前后壁,也有来自于左心房或左右心房的。结论:①上腔静脉肌袖是人和羊普遍存在的解剖结构,人的下腔静脉肌袖出现率明显低于羊,可能是上腔静脉肌袖引起局灶性心房颤动多于下腔静脉肌袖的解剖学基础。②上腔静脉肌袖是构成左右房的又一重要通路。  相似文献   
33.
Ectopic cervical or cervico-mediastinal thymomas are very rare and most of them are asymptomatic, except for the presence of a cervical mass. We present the case of a 71-year-old man with an ectopic cervico-mediastinal thymoma threatening superior vena cava syndrome. He had a slight headache and presented with venous dilatation on the chest wall. A computed tomographic scan and magnetic resonance, imaging of the chest demonstrated a mass extending from the right neck to the hilum, that indented the trachea and compressed and displaced the brachiocephalic veins anteriorly. Under a right hemicollar incision and median sternotomy, the mass was resected en bloc together with the thymus. The resected specimen was an encapsulated mass measuring 11×7×4 cm. The pathological diagnosis was type AB, non-invasive thymoma, confirmed by 3-color flow, cytometry of tumor-derived lymphocytes. Flow cytometry using biopsy material may contribute to the preoperative diagnosis of ectopic thymoma.  相似文献   
34.
The conceptual and methodological framework proposed by Doss (this issue) makes valuable suggestions for strategic choices in future research. This commentary addresses conceptual and terminological distinctions adopted by Doss, as well as his criticism of add-on/ dismantling studies. We also suggest research topics and methodological developments that could be integrated in Doss's framework to further expand understanding of therapeutic change.  相似文献   
35.
We describe the case of a recipient of an implantable cardioverter defibrillator with multiple syncopal episodes due both to superior vena cava obstruction and electrical instability. These complications occurred in the presence of two transvenous implantable cardioverter defibrillator leads. The patient has been managed conservatively with anticoagulants and new antiarrhythmic drugs with improvement in both his clinical problems.  相似文献   
36.
OBJECTIVE: Over the last 6 years, multidisciplinary teams (MDTs) have been established and play a key role in organizing the delivery of cancer care in the UK. There are no published data on the roles of their co-coordinators. To seek the views of colorectal multidisciplinary team co-ordinators (MDTCs) on what they do and how they do it. METHOD: Questionnaires were sent to the colorectal MDTC, or equivalent, in all 180 NHS hospital trusts in England and Wales where colorectal cancer surgery is performed. RESULTS: There was a 70% response rate. Seventy-one per cent of trusts now have a dedicated MDTC, whereas in 2002, only 40% had one. MDTCs generally keep their information on databases, but these differ, and are not coordinated with data entry into the national colorectal cancer database of the Association of Coloproctology of Great Britain and Ireland. In only 26 trusts does the MDTC communicate decisions to primary care, and the patients seem almost completely excluded from this process. CONCLUSION: The recently formed national MDTC Forum should grasp the opportunity of coordinating all of this well-intentioned but pluralistic activity to the benefit of patients, primary care and hospital teams. An effective MDTC with a robust database will be the key in achieving cancer waiting time targets with useful audit, thereby improving patient care.  相似文献   
37.
目的 观察在腕关节尺桡偏运动时,舟月骨间韧带(scapholunate interosseous ligament,SLIL)及其各亚区分级切断后对舟骨与月骨三维运动的影响,从亚区水平对SLIL在舟月骨三维运动中的作用进行研究.方法 取12例新鲜冰冻成人上肢标本(左、右侧各6例),共分为正常对照组、断SLIL近侧组、断SLIL近+背侧组、断SLIL近+掌侧组、SLIL全断组(每组6例).采用三维激光扫描及图像重建技术,测定在腕关节尺桡偏时舟骨与月骨的三维运动数据,并进行统计学处理.结果 在正常腕关节做尺桡偏运动时,舟、月骨同时也做尺桡偏运动,但还伴有明显的屈伸方向上的运动;与此同时,舟、月骨还做一定的旋前、旋后活动.在切断近+掌和近+背侧亚区组,舟月骨的活动受到影响.全切断SLIL会导致舟骨掌屈度增加,月骨掌屈活动减弱.结论 采用三维激光扫描及图像重建技术可准确测定腕舟月骨的三维活动度,从SLIL亚区水平上进行的研究表明,部分或全部切断SLIL后会对舟月骨的掌屈程度产生明显影响,但SLIL近侧亚区在控制舟、月骨的活动上不起主要作用.  相似文献   
38.
多层螺旋CT三维重建在左肾静脉压迫综合征中的临床应用   总被引:6,自引:0,他引:6  
目的探讨多层螺旋CT(MSCT)三维重建在左肾静脉压迫综合征中的诊断价值。方法应用16层螺旋CT对11例左肾静脉压迫综合征病例进行泌尿系增强多期扫描,并获得各种后处理图像。结果11例左肾静脉压迫综合征病例均可见肠系膜上动脉(SMA)压迫左肾静脉(LRV)的征象。CT多平面重建(MPR)直观地显示了腹主动脉(AO)与SMA之间的夹角(α),最大为21.88,°最小为12.86°,平均为17.95°。CT横断位图像显示扩张的左肾静脉直径为12~15.3 mm,平均为13.26 mm;LRV受SMA压迫狭窄处直径为3.0~4.0 mm,平均为3.26 mm。左侧卵巢静脉或睾丸静脉直径为2.1~2.6 mm,平均为2.2 mm。5例增强扫描肾实质期(后期)显示双肾实质密度相差20 HU以上。结论MSCT在胡桃夹综合征诊断中具有明显的优势。  相似文献   
39.
The activity of single neurons in the superior colliculus was recorded while a rhesus monkey made arm movements to visual targets located on a screen in front of him. It was found that the activity of a subpopulation of cells was clearly related to these arm movements. The neurons began to discharge either with the onset of the movement, during the movement period, or well before the onset of electromyogram (EMG) activity and movement, and could be active for the entire duration of EMG activity. While the discharge pattern of some of these'reach'neurons was not different for movements to different target positions, other cells showed graded changes in activity depending on the direction of movement. The peak discharge rate could rise to > 100 impulses/s. Some units received somatosensory input; other reach cells exhibited a visual response and/or presaccadic activity. It is likely that the primate superior colliculus is not only involved in the initiation and control of orientating movements of the eyes but also in reaching movements of the arms.  相似文献   
40.
将一种快速、灵敏、可靠、简便的抗癌活性微量测定技术——~3H—TdR前体掺入技术用于复方中药抗癌制剂制备工艺筛选,短期内即拟定出较合理的工艺,经临床及14项生物学指标综合评定,该制剂疗效好,无明显的毒副作用。表明把一些快速、灵敏的医学检测技术引入药物制备工艺、质量标准及稳定性研究,可克服由于活性成分不清楚带来的一些困难,拓宽了研究途径,提高了研究水平。  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