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   3502485篇
  免费   280121篇
  国内免费   31112篇
耳鼻咽喉   48425篇
儿科学   105883篇
妇产科学   89004篇
基础医学   482246篇
口腔科学   95489篇
临床医学   336961篇
内科学   659272篇
皮肤病学   69346篇
神经病学   276913篇
特种医学   138501篇
外国民族医学   1525篇
外科学   506453篇
综合类   142907篇
现状与发展   88篇
一般理论   1262篇
预防医学   278619篇
眼科学   83949篇
药学   274233篇
  438篇
中国医学   30102篇
肿瘤学   192102篇
  2021年   39167篇
  2019年   34208篇
  2018年   43946篇
  2017年   36067篇
  2016年   37606篇
  2015年   47020篇
  2014年   64301篇
  2013年   85668篇
  2012年   118451篇
  2011年   127348篇
  2010年   77916篇
  2009年   71513篇
  2008年   112236篇
  2007年   118110篇
  2006年   117927篇
  2005年   114463篇
  2004年   104911篇
  2003年   101548篇
  2002年   97949篇
  2001年   152943篇
  2000年   158067篇
  1999年   135278篇
  1998年   41945篇
  1997年   38367篇
  1996年   37228篇
  1995年   35822篇
  1994年   33226篇
  1993年   30149篇
  1992年   104979篇
  1991年   101851篇
  1990年   98247篇
  1989年   94407篇
  1988年   87297篇
  1987年   85929篇
  1986年   80973篇
  1985年   77259篇
  1984年   58474篇
  1983年   49729篇
  1982年   29901篇
  1979年   54310篇
  1978年   38022篇
  1977年   32163篇
  1976年   30220篇
  1975年   32113篇
  1974年   39154篇
  1973年   37315篇
  1972年   34792篇
  1971年   32006篇
  1970年   30305篇
  1969年   28041篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.

Background  

A standardised suction technique has been used to sample plasma proteins in dermal interstitial fluid (IF) serially for 5 to 6 days from a suction-induced skin mini-erosion. Increased protein concentrations ascribed to inflammation have been shown from day 1 onward. In this study, we assessed the effect of two different extraction pressures on IF sample composition.  相似文献   
992.
Acoustic analysis of a reading passage was used to identify the abnormal phonatory events associated with adductor spasmodic dysphonia (ADSD) pre- and postinjection of Botulinum Toxin A (Botox). Thirty-one patients (age 22 to 74 years) diagnosed with ADSD were included for study. All patients were new recipients of Botox, and the examination of their voice occurred before and after their initial injection of Botox. Acoustic events were identified from reading samples of the Rainbow Passage produced by each of the patients. These events were examined from sentences containing primarily voiced sound segments. Dependent variables included the number of phonatory breaks, frequency shifts, and aperiodic segments--all variables previously defined by the investigators. Additionally, calculated variables were made of the percentage of time these events occurred relative to the duration of the cumulative voiced segments. A sex- and age-matched control group (+/-2 years) was included for statistical comparison. Results indicated that those with ADSD produced more aberrant acoustic events than the controls. Aperiodicity was the predominant acoustic event produced during the reading, followed by frequency shifts and phonatory breaks. Within the ADSD group, the number of atypical acoustic events decreased following Botox injection. It is important that the occurrence of specific abnormal acoustic events was sufficient to differentiate the disordered speakers from the controls following as well as preceding initial Botox injection, as indicated by discriminant function analysis. This paper complements our previous work using this acoustic analysis method for defining the abnormal events present in the voice of those with ADSD and further suggests that these measures can be used in conjunction with perceptual impressions to differentiate speakers on the basis of initial severity.  相似文献   
993.
994.
Adolescent stress is an emerging area of importance in considerations of the health of young people. Exposure to stress predicts a range of both physical and mental health problems in adolescents and relates, as well, to the initiation of important health risk behaviours. Yet the measurement of stress in adolescents has been as fraught with methodological difficulty as it has been for adults. This paper examines the Adolescent Stress Questionnaire (ASQ) which was developed specifically to address the domain of stressors specific to adolescent experience and looks at three cohorts of responses to this questionnaire over time (1995, 1998 and 2001). It assesses the stability of the original 7‐factor structure of the ASQ over time, and while confirmatory factor analysis indicates that stability to be acceptable, it also suggests that either adolescent stressors themselves, or the language by which they are reported, vary sufficiently over time to warrant the refinement of the instrument. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
995.
报告12例缩窄性心包炎外科治疗的体会,本组病例的特点是病史长,入院前误诊率高(41.6%),心增厚达0.5-2cm,龟壳样变。结果:12例手术资料随访1-6a,手术疗效满意,认为对诊断明确者应及早手术治疗,尽可能彻底剥脱缩窄的心包是手术疗效的关键。  相似文献   
996.
997.
998.
OBJECTIVE: Traditional assessments of the microbial flora associated with acute bacterial rhinosinusitis have relied on maxillary sinus punctures (taps) and culture. These taps are now considered the gold standard for obtaining cultures and are used as the method of identifying bacterial pathogens in antimicrobial trials. Maxillary sinus taps are limited by discomfort to the patients and technical concerns. Because of these factors, the standard of performing taps has limited antibiotic trials and microbial surveillance. Alternatives to maxillary sinus taps have been explored. STUDY DESIGN: We conducted a retrospective, systematic review of the literature from 1950 to 2000 of articles comparing culture techniques in the nose and paranasal sinuses for acute bacterial rhinosinusitis. RESULTS: Nasal cultures have poor correlation to maxillary sinus cultures, whereas there is 60% to 85% concordance between endoscopically guided middle meatal cultures and maxillary sinus cultures. These studies, however, are all limited by small sample sizes and therefore are inadequate to make any concrete recommendations regarding the relative role of endoscopically guided middle meatal cultures as a formal method of pathogen identification in acute bacterial rhinosinusitis. CONCLUSION: A formal prospective study with sufficient sample size to assess the concordance between the microbial flora of the maxillary sinus punctures and middle meatal cultures in acute rhinosinusitis is recommended.  相似文献   
999.
OBJECTIVES: Diagnostic accuracy of the ThinPrep process (Cytyc, Boxborough, MA) was compared with that of conventional (smear) cytopreparation for fine-needle aspiration (FNA) of head and neck masses. METHODS: In a prospective, randomized, single-blinded study, 209 patients served as their own controls and underwent 236 FNAs using ThinPrep and conventional (smear) cytopreparatory techniques. RESULTS: ThinPrep produced less air-drying artifact and less mechanical distortion than the conventional method. The conventional technique was diagnostic in 63% of samples; the ThinPrep technique was diagnostic in 55% of samples. When all results were combined, pathologists subjectively preferred the conventional technique but accepted use of ThinPrep as the only cytopreparatory technique for most head and neck masses. CONCLUSIONS: For adequately experienced cytopathologists, ThinPrep is acceptable for FNA of salivary masses, neck cysts, metastatic lymph nodes, and thyroid lesions. Conventional smear technique should be used for FNA of nonmetastatic lymphoid lesions. Use of ThinPrep can complement use of the conventional (smear) cytopreparatory technique when aspirate is nondiagnostic or bloody, when the patient has a blood-borne infectious disease, when the clinician is inexperienced, or when aspirate has entered the syringe.  相似文献   
1000.
目的:探讨EB病毒感染与人大肠癌发生的关系。方法:用原位分子杂交法对130例人大肠癌标本中EB病毒小分子RNA片段进行检测。结果:130例标本中有6例(4.48%)癌组织呈阳性反应,其中4例为男性,4例有明显淋巴细胞浸润。结论:EB病毒感染可能与我国部分大肠腺癌的发生有关,肿瘤细胞间质中大量淋巴细胞浸润可能是EB病毒感染的重要病理学特征。  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