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   210027篇
  免费   19158篇
  国内免费   5034篇
耳鼻咽喉   2036篇
儿科学   4908篇
妇产科学   3292篇
基础医学   24319篇
口腔科学   5141篇
临床医学   21886篇
内科学   33809篇
皮肤病学   3310篇
神经病学   14370篇
特种医学   8721篇
外国民族医学   9篇
外科学   23144篇
综合类   22030篇
现状与发展   14篇
一般理论   106篇
预防医学   25901篇
眼科学   2964篇
药学   16278篇
  119篇
中国医学   8649篇
肿瘤学   13213篇
  2024年   574篇
  2023年   1949篇
  2022年   3642篇
  2021年   5450篇
  2020年   4633篇
  2019年   3725篇
  2018年   4733篇
  2017年   4927篇
  2016年   4606篇
  2015年   6429篇
  2014年   8307篇
  2013年   10805篇
  2012年   14781篇
  2011年   15188篇
  2010年   11066篇
  2009年   10630篇
  2008年   12834篇
  2007年   12774篇
  2006年   11801篇
  2005年   10296篇
  2004年   8152篇
  2003年   7319篇
  2002年   6405篇
  2001年   6210篇
  2000年   5571篇
  1999年   4493篇
  1998年   1989篇
  1997年   1715篇
  1996年   1779篇
  1995年   1446篇
  1994年   1314篇
  1993年   1202篇
  1992年   2831篇
  1991年   2522篇
  1990年   2392篇
  1989年   2266篇
  1988年   2069篇
  1987年   1804篇
  1986年   1725篇
  1985年   1647篇
  1984年   1184篇
  1983年   1044篇
  1982年   582篇
  1981年   519篇
  1980年   434篇
  1979年   883篇
  1978年   545篇
  1977年   463篇
  1974年   422篇
  1973年   412篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
目的介绍一种简单、快速的真菌DNA提取方法,提高真菌DNA提取效率,减少毒性和污染性,以适应临床研究需要。方法同时用溶细胞酶结合Biospin真菌基因组DNA提取试剂盒和十六烷基三甲基溴化铵(CTAB)法,提取白色念珠菌、热带念珠菌、克柔念珠菌和净平滑念珠菌基因组DNA,用A260/A280的比值检测DNA的纯度并计算质量浓度,同时行聚合酶链反应(PCR)以评价其可靠性。结果溶细胞酶结合Biospin真菌基因组DNA提取试剂成功提取所用真菌基因组DNA,其纯度及质量浓度能满足PCR反应的要求。结论用溶细胞酶结合Biospin真菌基因组DNA提取试剂提取DNA,简单、快速、高效,可用于PCR反应。  相似文献   
104.
105.
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   
106.
Introduction Choroid plexus cysts can lead to isolation of the lateral ventricles and distension of the third ventricle. We present an ultrasonographic video documentation of an infant with variably shaped and localized choroid plexus cyst of the third ventricle. Case report An infant had periods of increased intracranial pressure with changing dilatation of the first to third ventricle. Cerebral ultrasonography of the not crying boy demonstrated a choroid plexus cyst limply hanging down from the roof of the third ventricle to the beginning of the aqueduct of Sylvius. During crying, the cyst prolapsed from the third into left lateral ventricle and was strangled by the foramen of Monro. Endoscopic cyst fenestration and third ventriculostomy continuously solved the problem of intermittent hydrocephalus occlusus. Conclusion Depending not only on localization and size but also on cyst form and cerebrospinal fluid pressure, a single choroid plexus cyst can cause various obstructions of cerebrospinal fluid pathways.  相似文献   
107.
108.
109.
甲状腺癌淋巴结微转移的研究   总被引:2,自引:0,他引:2  
目的:探讨MUC1检测在甲状腺癌淋巴结微转移的可靠性和敏感性。方法:对488例甲状腺疾病手术患者于术前24h用1%美兰1.0~2.0mL注射于甲状腺结节或周围腺体,术中显示蓝染淋巴结,采用RT-PCR法测定临床蓝染淋巴结中的MUC1。 结果:蓝染淋巴结显示率甲状腺癌为93%,良性病例为0。研究组80个蓝染淋巴结中发现有MUC1mRNA表达的为95%,与病理诊断率(86%)相比有提高(P<0.05);良性病变(阴性对照组)淋巴结均不存在MUC1mRNA的表达;阳性对照组的癌转移性淋巴结均存在MUC1mRNA的表达。结论:MUC1较病理检查敏感,PCR产物点杂交进一步证实MUC1作为PCR标志物有较好的可靠性。  相似文献   
110.
OBJECTIVE: The purpose of this study was to evaluate the potential benefit of an ultrasonic device in apical surgery on the outcome of treatment. STUDY DESIGN: A randomized prospective design was used in a standardized treatment protocol. Patients were allocated to treatment with an ultrasonic device (P-Max Newtron) or treatment with a bur in an otherwise similar protocol. One year after treatment the results were evaluated by 2 oral and maxillofacial surgeons who were blinded for the therapy. RESULTS: Out of a total group of 399 patients who were included in the study, adequate follow-up could be obtained in 290 patients. The overall success rate in the ultrasonic group was 80.5% and in the group treated with a bur 70.9% (P = .056). In molars, the difference in success rate was significant (P = .02). CONCLUSION: The use of an ultrasonic device in apical surgery improved the outcome of treatment. In molars this effect was significant.  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