首页 | 官方网站   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   1596132篇
  免费   133485篇
  国内免费   2569篇
医药卫生   1732186篇
  2018年   14761篇
  2016年   12897篇
  2015年   15028篇
  2014年   20645篇
  2013年   31349篇
  2012年   42548篇
  2011年   44750篇
  2010年   26336篇
  2009年   25302篇
  2008年   42998篇
  2007年   45239篇
  2006年   46049篇
  2005年   44671篇
  2004年   44094篇
  2003年   42183篇
  2002年   41292篇
  2001年   75684篇
  2000年   78329篇
  1999年   66388篇
  1998年   17731篇
  1997年   16334篇
  1996年   16314篇
  1995年   16019篇
  1994年   15070篇
  1993年   14217篇
  1992年   55427篇
  1991年   53776篇
  1990年   52561篇
  1989年   50832篇
  1988年   47186篇
  1987年   46534篇
  1986年   44258篇
  1985年   42826篇
  1984年   31986篇
  1983年   27519篇
  1982年   16085篇
  1981年   14374篇
  1980年   13490篇
  1979年   30413篇
  1978年   21020篇
  1977年   17693篇
  1976年   16648篇
  1975年   17516篇
  1974年   21450篇
  1973年   20643篇
  1972年   18841篇
  1971年   17752篇
  1970年   16270篇
  1969年   15250篇
  1968年   13935篇
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
991.
992.
This study reports the purification and characterization of a high molecular weight human breast cancer-associated antigen identified by a previously described (1,2) murine monoclonal antibody, BCD-B4. Immunohistochemical analysis indicated that BCD-B4 recognizes an antigen expressed in an altered form on the human breast carcinoma cell line, BT-20, compared to the non-malignant human mammary epithelial cell line, HBL-100. Chemical treatments and enzymatic digestions suggested that the recognized moiety was a protein. The antigenic determinant was resistant to neuraminidase and periodate treatments but was sensitive to trypsin and proteinase K. The antigen was purified by affinity chromatography and its molecular weight, determined by SDS-PAGE analysis under non-reducing conditions, was proven to be 250 Kd. Under reducing conditions, the molecule dissociated into two polypeptides of 125 and 45 Kd, respectively. Both subunits could be isolated from normal HBL-100 and neoplastic BT-20 cellular protein extracts by affinity chromatography. The higher molecular weight subunit showed; however, qualitative and quantitative differences between the two cell lines: it was expressed in greater quantity on BT-20 cells and its molecular weight was 15 Kd higher. Both subunits could also be identified by immunoblots of BT-20 cells.  相似文献   
993.
994.
995.
996.
997.
Cough and paradoxical vocal fold motion   总被引:8,自引:0,他引:8  
OBJECTIVES: The differential diagnosis and treatment of patients with chronic cough, paradoxical vocal fold motion, and disordered breathing can be a challenge to most practicing otolaryngologists. Tracheobronchial (ie, asthma, bronchitis, and tracheal stenosis), laryngeal (ie, vocal fold paralysis and neoplasms), and rhinologic (ie, allergies and rhinosinusitis) etiologies are commonly diagnosed and treated effectively. However, occasionally one is faced with patients who are refractory to medical treatment and have no obvious rhinologic, laryngeal or pulmonary cause. STUDY DESIGN AND SETTING: We conducted a review of the literature. METHODS: We present a thorough review of the current medical literature exploring the complex neurologic mechanisms involved in the production of cough and the relationship between gastroesophageal reflux disease, vagal neurapathy, and paradoxical vocal fold motion. RESULTS: The diagnosis and successful treatment of chronic cough can be complex. It requires a thorough understanding of the neurologic mechanisms behind cough excitation and suppression. Successful treatment strategies include aggressive management of the patient's reactive airway disease, gastroesophageal reflux disease, and, in select cases, paradoxical vocal fold motion. This may involve a well-coordinated effort among pulmonologists, otolaryngologists, gastroenterologists, and speech pathologists. CONCLUSION: Gastroesophageal reflux disease, vagal neuropathy, and paradoxical vocal fold motion are additional causes of chronic cough and disordered breathing that need to be considered, in the absence of obvious laryngotracheal and/or rhinologic pathology. A high index of suspicion is essential in making the diagnosis and formulating an effective multidisciplinary treatment plan for these patients.  相似文献   
998.
999.
1000.
Tc-99m HMPAO was used to evaluate cerebral perfusion in a patient with tuberous sclerosis. The SPECT images demonstrated reduced HMPAO uptake in regions corresponding with MRI-confirmed locations of cortical tubers. These results indicate that the lesions are characterized by vascular perfusion deficits and support the hypothesis that cortical tubers result from developmental abnormalities of the embryonic central nervous system.  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-23

京公网安备 11010802026262号