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   1226篇
  免费   70篇
  国内免费   44篇
耳鼻咽喉   6篇
儿科学   58篇
妇产科学   21篇
基础医学   184篇
口腔科学   66篇
临床医学   103篇
内科学   270篇
皮肤病学   11篇
神经病学   97篇
特种医学   209篇
外国民族医学   1篇
外科学   55篇
综合类   19篇
预防医学   86篇
眼科学   14篇
药学   50篇
中国医学   1篇
肿瘤学   89篇
  2020年   6篇
  2019年   14篇
  2018年   9篇
  2017年   6篇
  2016年   5篇
  2015年   21篇
  2014年   26篇
  2013年   25篇
  2012年   17篇
  2011年   30篇
  2010年   25篇
  2009年   26篇
  2008年   39篇
  2007年   46篇
  2006年   34篇
  2005年   30篇
  2004年   25篇
  2003年   30篇
  2002年   36篇
  2001年   30篇
  2000年   25篇
  1999年   36篇
  1998年   39篇
  1997年   39篇
  1996年   41篇
  1995年   33篇
  1994年   50篇
  1993年   28篇
  1992年   22篇
  1991年   33篇
  1990年   29篇
  1989年   57篇
  1988年   47篇
  1987年   50篇
  1986年   59篇
  1985年   32篇
  1984年   34篇
  1983年   22篇
  1982年   15篇
  1981年   15篇
  1980年   12篇
  1979年   17篇
  1978年   8篇
  1977年   8篇
  1976年   10篇
  1975年   10篇
  1974年   6篇
  1973年   8篇
  1971年   7篇
  1970年   5篇
排序方式: 共有1340条查询结果,搜索用时 0 毫秒
61.
62.
63.
PURPOSE: The ASTRO Joint Working Group on Radiobiology Teaching, a committee composed of members having affiliations with several national radiation oncology and biology-related societies and organizations, commissioned a survey designed to address issues of manpower, curriculum standardization, and instructor feedback as they relate to resident training in radiation biology. METHODS AND MATERIALS: Radiation biology instructors at U.S. radiation oncology training programs were identified and asked to respond to a comprehensive electronic questionnaire dealing with instructor educational background, radiation biology course content, and sources of feedback with respect to curriculum planning and resident performance on standardized radiation biology examinations. RESULTS: Eighty-five radiation biology instructors were identified, representing 73 radiation oncology residency training programs. A total of 52 analyzable responses to the questionnaire were received, corresponding to a response rate of 61.2%. CONCLUSION: There is a decreasing supply of instructors qualified to teach classic, and to some extent, clinical, radiobiology to radiation oncology residents. Additionally, those instructors with classic training in radiobiology are less likely to be comfortable teaching cancer molecular biology or other topics in cancer biology. Thus, a gap exists in teaching the whole complement of cancer and radiobiology curricula, particularly in those programs in which the sole responsibility for teaching falls to one faculty member (50% of training programs are in this category). On average, the percentage of total teaching time devoted to classic radiobiology (50%), clinical radiobiology (30%), and molecular and cancer biology (20%) is appropriate, relative to the current makeup of the board examination. Nevertheless large variability exists between training programs with respect to the total number of contact hours per complete radiobiology course (ranging from approximately 10 to >50 h). A number of lecture topics, particularly in clinical radiobiology, are covered by fewer than 60% of training programs. A sizeable minority of radiation biology instructors are dissatisfied with the feedback they receive with respect to both course content and the performance of their residents on standardized radiobiology examinations administered by the American College of Radiology and/or the American Board of Radiology.  相似文献   
64.
1 临床资料我们总结2004-02/2004-06在第四军医大学唐都医院神经外科住院行栓塞治疗颅内动脉瘤患者27(男12,女15)例,年龄32~72岁.  相似文献   
65.
Lung cancer is not commonly known to metastasise to the perirenal space, with only five such cases previously published. We present an unusual case of perirenal lung metastases manifesting as diffuse perinephric stranding which to our knowledge has not been described before.  相似文献   
66.
Two hundred eighty-one sporadic Neisseria meningitidis serogroup B isolates, collected through active laboratory-based surveillance, were selected to be analyzed by PorA variable region (VR) typing to determine the prevalence of PorA types in the United States. A substantial number of distinct VR types were identified, 31 in VR1 and 41 in VR2. A total of 73 different PorA types were found, and 76. 7% of these types comprise nonprototype sequences in VR1, VR2, or both. The most prevalent PorA types were P1.7,16-20 (previously P1.7, 16i), P1.22,14, P1.22-1,14 (previously P1.22a,14), P1.7,16, P1.7-1,1 (previously P1.7d,1), P1.19,15, and P1.17,16-3 (previously P1.B,16d). No correlation was observed between the PorA types and geographic origin of the isolates. These data may aid in the design of an efficacious outer membrane protein-based vaccine by identifying the most appropriate PorA types for vaccine formulation. Studies are needed to fully evaluate the extent of cross-protection in humans among the variants and prototypes in each PorA VR family.  相似文献   
67.
Aboriginal people experience a disproportionate burden of HIV infection among the adult population in Canada; however, less is known regarding the prevalence and characteristics of HIV positivity among drug-using and street-involved Aboriginal youth. We examined HIV seroprevalence and risk factors among a cohort of 529 street-involved youth in Vancouver, Canada. At baseline, 15 (2.8%) were HIV positive, of whom 7 (46.7%) were Aboriginal. Aboriginal ethnicity was a significant correlate of HIV infection (odds ratio = 2.87, 95%CI: 1.02 – 8.09). Of the HIV positive participants, 2 (28.6%) Aboriginals and 6 (75.0%) non-Aboriginals reported injection drug use; furthermore, hepatitis C co-infection was significantly less common among Aboriginal participants (p = 0.041). These findings suggest that factors other than injection drug use may promote HIV transmission among street-involved Aboriginal youth, and provide further evidence that culturally appropriate and evidence-based interventions for HIV prevention among Aboriginal young people are urgently required.  相似文献   
68.
Giant cell myocarditis: most fatal of autoimmune diseases   总被引:1,自引:0,他引:1  
OBJECTIVE: To increase awareness of giant cell myocarditis (GCM), its pathogenesis, and treatment. METHODS: Review of relevant publications from the English-language literature. RESULTS: GCM is a rare, frequently fatal inflammatory disorder of cardiac muscle of unknown origin, characterized by widespread degeneration and necrosis of myocardial fibers.Congestive heart failure and ventricular tachycardia are common clinical manifestations. GCM occurs primarily in previously healthy adults, although it is frequently associated with various systemic diseases, primarily of autoimmune causes. The inflammatory infiltrate is characterized by the presence of multinucleated giant cells and is distinct from cardiac sarcoidosis. Animal models of GCM are similar to models of other autoimmune disorders such as rheumatoid arthritis. The prognosis, which is poor despite partial responsiveness to immunosuppressive medications, is improved with cardiac transplantation. CONCLUSIONS: The clinical and immunopathogenetic similarities with classical rheumatologic diseases, the differential diagnosis with sarcoidosis and other inflammatory conditions, and the use of standard immunosuppressive medications make GCM a disease process that should be added to the rheumatologist's expertise.  相似文献   
69.
70.
Age-related postural deficits elicit compensatory mechanisms such as ankle dorsiflexion in the elderly. To gain further insight into this problem, the ability to match an ankle angle during quiet stance was studied in 12 elderly and 12 young subjects. Following an initial single limb angular perturbation presented in the ±4° range, a subject had to return a tilt platform to level, as determined by the nonperturbed limb. Elderly subjects exhibited significant positive (0.9°) over-shoot of the level position, in contrast to young subjects who matched ankle angle with a mean error of −0.1°. The elderly group also exhibited an increase in positioning error for angular displacements in the range between −1 and +1°. The results document age-related postural changes in ankle positioning which might affect postural stability in older adults.  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