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   1963篇
  免费   310篇
  国内免费   41篇
耳鼻咽喉   14篇
儿科学   108篇
妇产科学   20篇
基础医学   97篇
口腔科学   26篇
临床医学   346篇
内科学   610篇
皮肤病学   62篇
神经病学   172篇
特种医学   280篇
外科学   320篇
综合类   34篇
预防医学   62篇
眼科学   16篇
药学   88篇
中国医学   1篇
肿瘤学   58篇
  2024年   9篇
  2023年   52篇
  2022年   15篇
  2021年   34篇
  2020年   92篇
  2019年   16篇
  2018年   93篇
  2017年   75篇
  2016年   74篇
  2015年   64篇
  2014年   97篇
  2013年   115篇
  2012年   58篇
  2011年   47篇
  2010年   86篇
  2009年   114篇
  2008年   53篇
  2007年   49篇
  2006年   52篇
  2005年   37篇
  2004年   24篇
  2003年   26篇
  2002年   25篇
  2001年   35篇
  2000年   28篇
  1999年   36篇
  1998年   82篇
  1997年   100篇
  1996年   78篇
  1995年   70篇
  1994年   50篇
  1993年   52篇
  1992年   33篇
  1991年   19篇
  1990年   31篇
  1989年   57篇
  1988年   57篇
  1987年   40篇
  1986年   29篇
  1985年   28篇
  1984年   17篇
  1983年   11篇
  1982年   15篇
  1981年   16篇
  1980年   16篇
  1979年   12篇
  1978年   11篇
  1977年   9篇
  1976年   11篇
  1971年   11篇
排序方式: 共有2314条查询结果,搜索用时 10 毫秒
991.
992.
In summary, ambulatory surgery requires patients and their families to assume responsibilities previously held by health care providers. These include preserving NPO instructions without the benefit of nurses present to prevent a break in the fast. Nurses responsibilities then, take on a different meaning. An essential nursing objective is to enlighten patients.  相似文献   
993.
Previous studies have demonstrated that blood pressure falls postprandially in fit elderly subjects, the greatest changes occurring after meals with a high carbohydrate content. To evaluate the influence of the type of carbohydrate on postprandial blood pressure, the effects of equivalent energy content (2.4 MJ) high complex (starch) and high simple (monosaccharide) carbohydrate meals were studied in seven healthy elderly subjects. Blood pressure, heart rate, autonomic function, plasma catecholamines, insulin and neurotensin levels were measured pre- and postprandially. Greater falls in supine and erect systolic blood pressure occurred after the high simple than the high complex carbohydrate meal (p < 0.05). No differences were found in supine or erect diastolic blood pressure, heart rate or in any of the biochemical parameters measured between the meal types. It is concluded that a simple carbohydrate meal results in a greater postprandial fall in blood pressure than an equivalent energy complex carbohydrate meal in the elderly, although the mechanisms for these changes are unknown.  相似文献   
994.
995.
A patient with recurrent episodes of dizziness and blackouts is described. Detailed cardiac and neurological investigations were normal. Autonomic assessment excluded postural hypotension and confirmed normal sympathetic vasoconstrictor function. Cardiac parasympathetic function in response to deep breathing, hyperventilation and ocular pressure was normal. Left carotid sinus massage only reproducibly lowered blood pressure with minimal change in heart rate. This occurred mainly during head-up tilt. The fall in blood pressure was not affected by the muscarinic blocker atropine, or the peptide release inhibitor, octreotide. A diagnosis of left carotid sinus hypersensitivity of the vasodepressor variety was made. Left carotid sinus denervation was performed. This successfully prevented further episodes of dizziness and blackouts. The ability to measure beat-to-beat blood pressure non-invasively was of particular importance in diagnosis, and in the assessment of management options in this patient.  相似文献   
996.
997.
998.
Radiation absorbed dose to the lens in dacryoscintigraphy with 99mTcO4-   总被引:1,自引:0,他引:1  
  相似文献   
999.
1000.
The posttransplantation lymphoproliferative disorders (PT-LPDs) are a morphologically heterogeneous group of Epstein-Barr virus (EBV)-driven lymphoid proliferations of varying clonal composition. Some PT-LPDs regress after a reduction in immunosuppression, while others progress in spite of aggressive therapy. Previously defined morphologic categories do not correlate with clonality, and neither morphology nor clonality has reliably predicted the clinical behavior of PT-LPDs. We investigated 28 PT-LPD lesions occurring in 22 patients for activating alterations involving the bcl-1, bcl-2, c-myc, and H-, K- and N-ras proto-oncogenes and for mutations involving the p53 tumor suppressor gene. We correlated the results of these studies with the morphology of the lesions, their clonality based on Ig heavy and light chain gene rearrangement analysis, and the presence and clonality of EBV infection. We found that the PT-LPDs are divisible into three distinct categories as follows: (1) plasmacytic hyperplasia: most commonly arise in the oropharynx or lymph nodes, are nearly always polyclonal, usually contain multiple EBV infection events or only a minor cell population infected by a single form of EBV, and lack oncogene and tumor suppressor gene alterations; (2) polymorphic B-cell hyperplasia and polymorphic B-cell lymphoma: may arise in lymph nodes or various extranodal sites, are nearly always monoclonal, usually contain a single form of EBV, and lack oncogene and tumor suppressor gene alterations; and (3) immunoblastic lymphoma or multiple myeloma: present with widely disseminated disease, are monoclonal, contain a single form of EBV, and contain alterations of one or more oncogene or tumor suppressor genes (N-ras gene codon 61 point mutation, p53 gene mutation, or c-myc gene rearrangement). The PT-LPDs are divisible into three categories exhibiting distinct morphologic and molecular genetic characteristics. Alterations involving the N-ras and c-myc proto- oncogenes and the p53 tumor suppressor gene may play an important role in the development and/or progression of the PT-LPDs.  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