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   121126篇
  免费   6451篇
  国内免费   150篇
耳鼻咽喉   1883篇
儿科学   5276篇
妇产科学   4026篇
基础医学   16867篇
口腔科学   2862篇
临床医学   8962篇
内科学   23192篇
皮肤病学   3445篇
神经病学   9436篇
特种医学   5247篇
外国民族医学   41篇
外科学   19637篇
综合类   1638篇
一般理论   30篇
预防医学   6092篇
眼科学   3651篇
药学   8327篇
  1篇
中国医学   328篇
肿瘤学   6786篇
  2018年   972篇
  2017年   844篇
  2016年   1153篇
  2015年   1305篇
  2014年   1713篇
  2013年   2508篇
  2012年   3327篇
  2011年   3399篇
  2010年   2125篇
  2009年   2049篇
  2008年   3477篇
  2007年   3738篇
  2006年   3813篇
  2005年   3981篇
  2004年   3896篇
  2003年   3757篇
  2002年   3700篇
  2001年   7190篇
  2000年   7145篇
  1999年   6008篇
  1998年   1687篇
  1997年   1600篇
  1996年   1387篇
  1995年   1257篇
  1994年   1140篇
  1993年   1138篇
  1992年   3877篇
  1991年   3693篇
  1990年   3666篇
  1989年   3441篇
  1988年   3085篇
  1987年   2985篇
  1986年   2889篇
  1985年   2682篇
  1984年   2004篇
  1983年   1663篇
  1982年   978篇
  1981年   964篇
  1980年   804篇
  1979年   1890篇
  1978年   1385篇
  1977年   1146篇
  1976年   980篇
  1975年   1212篇
  1974年   1248篇
  1973年   1230篇
  1972年   1070篇
  1971年   1001篇
  1970年   904篇
  1969年   816篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
 Because the immunomodulatory effects of antibiotics could possibly influence the degree of the systemic and local response to infection, knowledge of their intrinsic influence on the host's inflammatory response appears to be essential. Therefore, this study investigated the effects of frequently used antimicrobial agents (β-lactams, quinolones gentamicin, vancomycin and metronidazole) on the in-vitro tumor necrosis factor (TNF)-α and interleukin (IL)-6 production of isolated human peripheral blood mononuclear cells (PBMNC), cultured with or without endotoxin, in comparison with those effects obtained in a whole-blood assay system. In the presence of ciprofloxacin, ofloxacin, gentamicin, vancomycin, and metronidazole, a significant inhibition of the endotoxin-stimulated TNF-α production of human peripheral blood mononuclear cells (PBMNC) was found at therapeutic levels. Only ofloxacin showed a significant inhibitory influence on the endotoxin-induced IL-6 production of PBMNC. In the whole-blood assay, significant effects were not detectable. None of the antibiotics showed cytotoxicity. It is concluded that, at present, the direct immunological effects of antibiotics should be interpreted carefully with regard to the experimental conditions, and regardless of the therapeutic implications. To assess the potential direct immunomodulatory effect of antimicrobial agents, different cell culture procedures should be used. Received: October 19, 2001 / Accepted: February 15, 2002  相似文献   
92.
Static analysis with finite element of a realistic femur nail bone-implant system in a typical proximal femoral fracture under physiological load bearing situations provides results for stress, displacement and strain. The question to be answered is, if simulation with the finite element analysis is able to explain biomechanically clinical observed patterns of failure. Surface-Reconstruction with CT database of a proximal femur and reconstruction with CT based density data was done. Next steps were to unite the bone structure with the Proximal Femoral Nail and to model two relevant fractures (31-A2.2 and A2.3 according AO). After modelling of geometry, isotropic material behaviour and load application numeric calculation of the femur-nail system with FE-software was performed. FE simulation mainly shows an axial dislocation of the femoral head screw with nearly no dislocation of the antirotation screw. This so-called z-effect therefore means: (1) Tilting of the proximal main fragment around the sagittal axis between the screws and (2) relative movement of both screws in the frontal plane. Relative movement of the two screws against each other could be the reason for implant failure, the so called cut out. Furthermore simulation shows different gliding of the screws explaining the so called z-telescoping. The analyzed stress patterns have to be relativized, because isotropic material behaviour of cancellous bone was assumed. Further examinations for this issue are necessary.  相似文献   
93.
Occupational diseases Nos. 2108 and 2110 correspond to intervertebral disc-related diseases of the lumbar spine from many years of carrying or lifting heavy loads, occupations in extreme postures of full flexion or oscillation of the whole body when seated, and which compel the cessation of all activities which are or could be the cause for the origin, exacerbation or recurrence of the disease. These occupational diseases came into force at the start of 1993, but there have been considerable problems in their implementation. The present Part I of the contribution is the result of the work of an interdisciplinary study group and contains medical criteria for the assessment of possibly strain-related clinical characteristics and the evaluation of other possible causes. Part II is to be published in Volume 4/2005 and will deal with questions related to forced cessation and to the assessment of the loss of earning ability. Agreement was reached in many areas related to the assessment of occupational claims. This should allow for evidence-based decision making in the future for the occupational diseases Nos. 2108 and 2110.  相似文献   
94.
95.
96.
97.
The information contained in package inserts varies from country to country in Europe, although other regulatory aspects of data presentation are quite similar. West Germany's Drug Law of 1976 requires 11 items to be included in the package insert for both patient and health professional: name/address of manufacturer; drug name; active constituents; indications; contraindications; side effects; drug interactions; dosage instructions; method and duration of application; statement that drug should not be used after expiration date; and statement that drug should be kept out of reach of children. All information must be submitted to the Health Office at the time of application or the applicant is liable for criminal prosecution. Documentation of side effects must be complete, although no special form is required. Similarly, causality assessment needs to be made even though specific algorithms are not required. Proposed amendments to the Drug Law will include additional information to physicians concerning the overdose instructions, pharmacological properties, and bioavailability of the drug. Registration procedures are the same throughout Europe and are called Summary of Products Characteristics. Assessment reports are also required for each new chemical entity in the European Community.  相似文献   
98.
BACKGROUND: Studies of the association between indoor allergen exposure and the development of allergic diseases have often measured allergen exposure at one point in time. OBJECTIVE: We investigated the variability of house dust mite (Der p 1, Der f 1) and cat (Fel d 1) allergen in Dutch homes over a period of 8 years. METHODS: Data were obtained in the Dutch PIAMA birth cohort study. Dust from the child's mattress, the parents' mattress and the living room floor was collected at four points in time, when the child was 3 months, 4, 6 and 8 years old. Dust samples were analysed for Der p 1, Der f 1 and Fel d 1 by sandwich enzyme immuno assay. RESULTS: Mite allergen concentrations for the child's mattress, the parents' mattress and the living room floor were moderately correlated between time-points. Agreement was better for cat allergen. For Der p 1 and Der f 1 on the child's mattress, the within-home variance was close to or smaller than the between-home variance in most cases. For Fel d 1, the within-home variance was almost always smaller than the between-home variance. Results were similar for allergen levels expressed per gram of dust and allergen levels expressed per square metre of the sampled surface. Variance ratios were smaller when samples were taken at shorter time intervals than at longer time intervals. CONCLUSION: Over a period of 4 years, mite and cat allergens measured in house dust are sufficiently stable to use single measurements with confidence in epidemiological studies. The within-home variance was larger when samples were taken 8 years apart so that over such long periods, repetition of sampling is recommended.  相似文献   
99.
100.
The article examines the question whether and – if – under which conditions physicians should perform purely esthetic interventions. Starting point of the considerations is the special character of the medical profession and the necessity of the anticipated confidence in the system of medicine. The medical measures for aesthetic improvement are systematized. Medical measures to increase the wanted, positively felt attention of others are not compellingly required according to the medical ethic. Nevertheless they do not offend the ethos if high quality standards are insured: The measures must be presumably helpful for the patient; a thorough informed consent and avoidance of damage must be insured. Esthetic measures, in particular operations which are totally cosmetic, should be limited strictly if performed with children and adolescents. Nevertheless convincing arguments support medical-esthetic measures with children and adolescents to avoid stigmatization.  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