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   1022篇
  免费   54篇
  国内免费   5篇
耳鼻咽喉   16篇
儿科学   20篇
妇产科学   10篇
基础医学   167篇
口腔科学   20篇
临床医学   71篇
内科学   168篇
皮肤病学   11篇
神经病学   274篇
特种医学   40篇
外科学   140篇
综合类   10篇
预防医学   48篇
眼科学   3篇
药学   34篇
肿瘤学   49篇
  2023年   7篇
  2022年   14篇
  2021年   28篇
  2020年   15篇
  2019年   30篇
  2018年   29篇
  2017年   25篇
  2016年   20篇
  2015年   24篇
  2014年   18篇
  2013年   34篇
  2012年   63篇
  2011年   66篇
  2010年   38篇
  2009年   52篇
  2008年   74篇
  2007年   53篇
  2006年   42篇
  2005年   47篇
  2004年   44篇
  2003年   29篇
  2002年   37篇
  2001年   27篇
  2000年   27篇
  1999年   26篇
  1998年   7篇
  1997年   4篇
  1996年   10篇
  1995年   8篇
  1994年   4篇
  1993年   4篇
  1992年   14篇
  1991年   13篇
  1990年   19篇
  1989年   10篇
  1988年   11篇
  1987年   13篇
  1986年   14篇
  1985年   8篇
  1984年   4篇
  1982年   6篇
  1981年   6篇
  1980年   5篇
  1979年   6篇
  1977年   4篇
  1975年   4篇
  1974年   8篇
  1973年   9篇
  1970年   3篇
  1969年   3篇
排序方式: 共有1081条查询结果,搜索用时 89 毫秒
991.
992.
Studies of the broader autism phenotype, and of subtle changes in autism symptoms over time, have been compromised by a lack of established quantitative assessment tools. The Social Responsiveness Scale (SRS—formerly known as the Social Reciprocity Scale) is a new instrument that can be completed by parents and/or teachers in 15–20 minutes. We compared the SRS with the Autism Diagnostic Interview-Revised (ADI-R) in 61 child psychiatric patients. Correlations between SRS scores and ADI-R algorithm scores for DSM-IV criterion sets were on the order of 0.7. SRS scores were unrelated to I.Q. and exhibited inter-rater reliability on the order of 0.8. The SRS is a valid quantitative measure of autistic traits, feasible for use in clinical settings and for large-scale research studies of autism spectrum conditions.  相似文献   
993.
Angiotensin II (ANG II) is the main effector peptide in the renin-angiotensin system. It is generated by the activation of Angiotensin I through the Angiotensin II Converter Enzyme (ACE II). ANG II has multiple physiologic effects that regulate vascular tone, hormone secretion, tissue growth and neural activity. It has systemic (endocrine) and local (paracrine and autocrine) effects, favoring cell growth and differentiation through four types of receptors from which types 1 and 2 (AT(1) and AT(2)) are the most important. Stimulation of AT(1) leads to the activation of intracellular pathways that finally lead to vasoconstriction, inflammation and proliferation. The AT(2) receptor is mainly expressed in fetal tissue and scantly in the cardiovascular system under different circumstances. Its effects are opposite to those of the AT(1). The stimulation of AT(1) activates second messengers that lead to a rapid production of diacylglycerol and 1-4-5-inositol triphosphate, as well as to the activation of C protein. Several reports indicate that ANG II can induce neovascularization in experimental systems due to the expression of different growth factors such as angiopoietin 2, vascular endothelial factor, and its receptor, fibroblast growth factor, platelet derived growth factor, transforming growth factor beta and epidermal growth factor. Other mechanisms associated with ANG II induced angiogenesis are nitric oxide synthase and metalloproteinase expression, as well as inflammation induction. Angiogenesis is a fundamental process to tissue repair and development, and it participates in several pathologic processes. In addition, the AT(1) receptor is expressed in many malignant neoplasms and its blockade through ECA II inhibitors and ANG II antagonists has shown antineoplastic activity as well as angiogenesis inhibition in tumoral experimental models. This review discusses the mechanisms by which ANG II participates in neoplastic and non-neoplastic tissue angiogenesis and its possible therapeutic implications.  相似文献   
994.
Endobronchial hamartoma   总被引:9,自引:0,他引:9  
OBJECTIVES: To describe clinical, endoscopic, radiographic, and follow-up characteristics of a series of patients in whom endobronchial hamartoma (EH) had been diagnosed. METHODS: Retrospective study of all cases of hamartoma diagnosed by bronchial biopsy between 1974 and 1997 in a tertiary referral hospital in Madrid, Spain. RESULTS: EH was diagnosed 47 patients during the study period. Four patients were excluded from the study because no clinical history was available. We analyzed the cases of 43 patients (37 men and 6 women), with a mean (+/- SD) age of 62 +/- 12 years. Seven patients had a concurrent lung neoplasm, and the EH was an incidental endoscopic finding. Among the other 36 patients, 31 had a new onset of respiratory symptoms, most commonly, recurrent respiratory infections in 16 patients (44%) and hemoptysis in a further 12 patients (33.4%). Chest radiograph findings were abnormal in 38 of 43 patients. At bronchoscopy, the lesions were equally distributed throughout the right and left lungs with no clear lobar predilection. Endobronchial obstruction was evident in 26 patients (72.2%) without concurrent neoplasm, 17 of whom underwent resection with a rigid bronchoscope and laser, with total resolution in 13 patients. Partial resolution was achieved in four patients, two of whom needed a second endoscopic procedure. Five patients were treated with open lung surgery. Clinical and endoscopic follow-up was performed in 23 patients at 1 to 73 months (mean, 17 months), and recurrence was found in 4 patients. CONCLUSION: EH frequently produces respiratory complaints and radiographic abnormalities. Patients with endobronchial obstructions had satisfactory responses to endoscopic therapy.  相似文献   
995.
996.
997.
E Luevano  M Tena  A Zamora  J Sotelo 《Oncology》1986,43(6):364-367
Glial fibrillary acidic protein has been widely used in neurobiology and neuropathology as a specific marker for normal and abnormal astrocytes. Here, we report the immunostaining of 107 brain tumors and controls using an antiserum against glial fibrillary acidic protein. Selection of astroglia-derived tumors was easy and of high accuracy. Pattern of staining and usefulness of the method are described.  相似文献   
998.
Multifocal epithelial hyperplasia (MEH) is also known as focal epithelial hyperplasia, Heck's disease or multifocal papillomavirus-induced epithelial hyperplasia. It is characterised by the presence of multiple lesions in the oral mucosa of children and it has been associated with the presence of the human papillomavirus. The aim of this study was to determine the clinico-pathological features of the cases diagnosed as MEH in the Service of Dermatology of the Hospital Manuel Gea González (SDHMGG). The files of the SDHMGG were reviewed and all cases diagnosed as MEH were retrieved. Nine MEH cases were found. Most of the patients were 20 year-old or younger (67%) and females were more commonly affected (78%). All patients presented multiple lesions and always, close relatives with similar lesions were found. Lesions were located most commonly in the buccal mucosa, lower lip and commissures. MEH is a soft tissue intraoral condition that needs treatment solely of the traumatised lesions or those with cosmetic problems. Remaining lesions will disappear with the age of the patients. It is suggested that this entity should be named multifocal epithelial hyperplasia since this name describes better the clinico-pathological and microscopic features of the disease.  相似文献   
999.
1000.
Biliverdin therapy protects rat livers from ischemia and reperfusion injury   总被引:13,自引:0,他引:13  
Heme oxygenase (HO-1) provides a cellular defense mechanism during oxidative stress and catalyzes the rate-limiting step in heme metabolism that produces biliverdin (BV). The role of BV and its potential use in preventing ischemia/reperfusion injury (IRI) had never been studied. This study was designed to explore putative cytoprotective functions of BV during hepatic IRI in rat liver models of ex vivo perfusion and orthotopic liver transplantation (OLT) after prolonged periods of cold ischemia. In an ex vivo hepatic IRI model, adjunctive BV improved portal venous blood flow, increased bile production, and decreased hepatocellular damage. These findings were correlated with amelioration of histological features of IRI, as assessed by Suzuki's criteria. Following cold ischemia and syngeneic OLT, BV therapy extended animal survival from 50% in untreated controls to 90% to 100%. This effect correlated with improved liver function and preserved hepatic architecture. Additionally, BV adjuvant after OLT decreased endothelial expression of cellular adhesion molecules (P-selectin and intracellular adhesion molecule 1), and decreased the extent of infiltration by neutrophils and inflammatory macrophages. BV also inhibited expression of inducible nitric oxide synthase and proinflammatory cytokines (interleukin 1beta, tumor necrosis factor alpha, and interleukin 6) in OLTs. Finally, BV therapy promoted an increased expression of antiapoptotic molecules independently of HO-1 expression, consistent with BV being an important mediator through which HO-1 prevents cell death. In conclusion, this study documents and dissects potent cytoprotective effects of BV in well-established rat models of hepatic IRI. Our results provide the rationale for a novel therapeutic approach using BV to maximize the function and thus the availability of donor organs.  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