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   1085382篇
  免费   74777篇
  国内免费   1760篇
耳鼻咽喉   15079篇
儿科学   29359篇
妇产科学   26541篇
基础医学   153538篇
口腔科学   35327篇
临床医学   91778篇
内科学   217233篇
皮肤病学   23192篇
神经病学   84942篇
特种医学   41464篇
外国民族医学   105篇
外科学   170971篇
综合类   19310篇
现状与发展   2篇
一般理论   290篇
预防医学   77979篇
眼科学   24086篇
药学   81835篇
  3篇
中国医学   2794篇
肿瘤学   66091篇
  2021年   8956篇
  2019年   9080篇
  2018年   13341篇
  2017年   10270篇
  2016年   10813篇
  2015年   12471篇
  2014年   16955篇
  2013年   23730篇
  2012年   33790篇
  2011年   35150篇
  2010年   19943篇
  2009年   18816篇
  2008年   32404篇
  2007年   34078篇
  2006年   34201篇
  2005年   33362篇
  2004年   32053篇
  2003年   30460篇
  2002年   28268篇
  2001年   58897篇
  2000年   60659篇
  1999年   50557篇
  1998年   12084篇
  1997年   10593篇
  1996年   10705篇
  1995年   9885篇
  1994年   9204篇
  1993年   8451篇
  1992年   37774篇
  1991年   36132篇
  1990年   34769篇
  1989年   33895篇
  1988年   30822篇
  1987年   29946篇
  1986年   27917篇
  1985年   26701篇
  1984年   18946篇
  1983年   16042篇
  1982年   8300篇
  1979年   16614篇
  1978年   11141篇
  1977年   9485篇
  1976年   8244篇
  1975年   9124篇
  1974年   10960篇
  1973年   10362篇
  1972年   9772篇
  1971年   9233篇
  1970年   8840篇
  1969年   8337篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Epidermolysis bullosa acquisita (EBA) is an acquired subepidermal bullous disease characterized by IgG autoantibodies directed against type VII collagen, the major component of anchoring fibrils. The classical phenotype of EBA is a non-inflammatory, mechanobullous disease resembling the dystrophic forms of inherited epidermolysis bullosa. Mucous membrane involvement is frequent but usually mild. We report a 1-year-old girl suffering from IgA-EBA, who presented with an initial eruption of disseminated urticarial lesions and tense blisters of the skin but subsequently developed severe oral and ocular lesions reminiscent of cicatricial pemphigoid. Direct immunofluorescence of the skin and buccal mucosa revealed linear IgA and C3 at the basement membrane zone (BMZ). IgA anti-BMZ autoantibodies stained the dermal side of salt-split skin by indirect immunofluorescence and recognized a dermal protein of 290 kDa co-migrating with type VII collagen by immunoblotting. Direct and indirect immunoelectron microscopy revealed IgA deposits overlying the anchoring fibrils. The ocular involvement led to total blindness in spite of intense treatment. This case of childhood IgA-EBA is particularly striking because of the cicatricial pemphigoid phenotype with severe ocular involvement which resulted in blindness. It reinforces the necessity to use modern immunological methods to classify autoimmune bullous diseases in order to allow early and appropriate treatment.  相似文献   
992.
The purpose of this study was to compare gated with nongated three-dimensional fetal echocardiography in terms of the ability to demonstrate fetal cardiac anatomy. We examined nine fetuses in utero using conventional two-dimensional sonographic imaging equipment, an electromagnetic position sensor, and a computer-graphics workstation. Free-hand sweeps were performed through the fetal heart and great vessels in either transverse or sagittal orientations with respect to the fetal heart. Seven transverse and five sagittal sweeps were selected for reconstruction and analysis. Cardiac gating was performed by using a temporal Fourier transform to determine the fundamental frequency of cardiac motion. Two-dimensional data from each sweep were reprojected to a series of volume data sets. Each series was then condensed to a single volume, so that each two-dimensional sweep could be compared with its respective gated and nongated volume data sets. The two-dimensional data were reviewed utilizing a display with forward and backward cineloop capability. The gated and nongated volume data sets were displayed interactively as a series of three orthogonal planes, with the ability of the observer to control the location of each image plane within the volume. The gated data were animated with variable display frame rates. Conventional two-dimensional imaging provided a fairly complete evaluation of the fetal heart when scanning included the four-chamber view with a sweep across the outflow tracts. Nongated three-dimensional fetal echocardiography allowed visualization of some structures and views not demonstrated with two-dimensional ultrasonography. Gated three-dimensional fetal echocardiography provided significantly better visualization and comprehension of cardiac anatomy than nongated three-dimensional fetal echocardiography. The superiority of gated over nongated three-dimensional fetal echocardiography appears to come from both improved image quality and the anatomic clues that derive from the ability to view cardiac motion.  相似文献   
993.
As presently understood, evidence based medicine aims to advance practice from its traditional unverifiable mix of art and science to rational use of measurable inputs and outputs. In practice, however, its advocates accept uncritically a desocialised definition of science, assume that major clinical decisions are taken at the level of secondary specialist rather than primary generalist care, and ignore the multiple nature of most clinical problems, as well as the complexity of social problems within which clinical problems arise and have to be solved. These reductionist assumptions derive from the use of evidence based medicine as a tool for managed care in a transactional model for consultations. If these assumptions persist, they will strengthen reification of disease and promote the episodic output of process regardless of health outcome. We need to work within a different paradigm based on development of patients as co-producers rather than consumers, promoting continuing output of health gain through shared decisions using all relevant evidence, within a broader, socialised definition of science. Adoption of this model would require a major social and cultural shift for health professionals. This shift has already begun, promoted by changes in public attitudes to professional authority, changes in the relation of professionals to managers, and pressures for improved effectiveness and efficiency which, contrary to received wisdom, seem more likely to endorse cooperative than transactional clinical production. Progress on these lines is resisted by rapidly growing and extremely powerful economic and political interests. Health professionals and strategists have yet to recognise and admit the existence of this choice.  相似文献   
994.
995.
996.
Background : Barrett's oesophagus is thought to be a complication of severe gastro-oesophageal reflux.
Aim : To determine whether the proton pump inhibitor, lansoprazole, is effective in healing erosive reflux oesophagitis in patients with Barrett's oesophagus.
Methods : An 8-week, randomized, double-blind study was conducted using patients with both erosive reflux oesophagitis and Barrett's oesophagus. Erosive reflux oesophagitis was defined as grades 2–4 oesophagitis; Barrett's oesophagus, as specialized columnar epithelium obtained by biopsy from the tubular oesophagus; and healing, as a return to grade 0 or 1 oesophageal mucosa (complete re-epithelialization). One-hundred and five (105) patients from one centre were randomized to receive either lansoprazole 30 mg daily or ranitidine 150 mg twice daily. Unhealed or symptomatic lansoprazole patients at week 4 were randomized to receive the same 30 mg dose daily or an increased dose of 60 mg daily. Endoscopy was performed at baseline and at weeks 2, 4, 6 and 8.
Results : The treatment groups were similar in regards to baseline characteristics, erosive reflux oesophagitis grades and length of Barrett's oesophagus. At each 2-week interval, lansoprazole patients had significantly greater healing rates and less day and night heartburn and regurgitation than ranitidine patients. There were no significant differences between treatment groups in antacid use, quality of life parameters, or rate of reported adverse events. Median values for fasting serum gastrin levels remained within the normal range for both groups.
Conclusion : In patients with both Barrett's oesophagus and erosive reflux oesophagitis, lansoprazole is significantly more effective than ranitidine in relieving reflux symptoms and healing erosive reflux oesophagitis.  相似文献   
997.
998.
999.
Cranial malignant fibrous histiocytomas are rare tumors. Most are hypervascular, destructive masses that are similar to other malignant lesions and to malignant fibrous histiocytomas found elsewhere in the body. We describe a myxoid malignant fibrous histiocytoma of the temporal bone, possibly of dural origin, with features that more closely resembled a meningioma at CT, MR imaging, and angiography.  相似文献   
1000.
The impact of a cancer diagnosis upon a family has become a focus of clinical interest, but few scientific studies have been completed in this area. The objectives of this pilot study were twofold: first, to test the applicability of the Family System Test (FAST) in families (n=5) with a young adult member with cancer and secondly to evaluate patterns of interactions within these families. Results show that the FAST is applicable and useful to evaluate the different perceptions of hierarchy and cohesion - two essential variables - within these families. The great majority of family members represented their relationships as balanced (i.e., cohesive and moderately hierarchical). However, contrary to nonclinical families, fathers had a less positive view than mothers and patients: fathers more often perceived family and parenteral relations as unbalanced, and also more often perceived a reversal of hierarchy and a cross-generational coalition within the family. Implications for future research and clinical care are discussed.  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