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   57091篇
  免费   4694篇
  国内免费   153篇
耳鼻咽喉   511篇
儿科学   1520篇
妇产科学   1083篇
基础医学   7620篇
口腔科学   965篇
临床医学   6314篇
内科学   10938篇
皮肤病学   809篇
神经病学   5115篇
特种医学   2199篇
外科学   9423篇
综合类   798篇
一般理论   59篇
预防医学   5688篇
眼科学   1269篇
药学   4145篇
  1篇
中国医学   53篇
肿瘤学   3428篇
  2023年   295篇
  2022年   370篇
  2021年   1165篇
  2020年   663篇
  2019年   1098篇
  2018年   1313篇
  2017年   956篇
  2016年   1033篇
  2015年   1242篇
  2014年   1815篇
  2013年   2519篇
  2012年   3845篇
  2011年   3917篇
  2010年   2133篇
  2009年   1898篇
  2008年   3428篇
  2007年   3678篇
  2006年   3573篇
  2005年   3484篇
  2004年   3226篇
  2003年   3067篇
  2002年   2881篇
  2001年   925篇
  2000年   879篇
  1999年   873篇
  1998年   661篇
  1997年   527篇
  1996年   498篇
  1995年   523篇
  1994年   437篇
  1993年   410篇
  1992年   578篇
  1991年   521篇
  1990年   528篇
  1989年   498篇
  1988年   464篇
  1987年   396篇
  1986年   411篇
  1985年   452篇
  1984年   382篇
  1983年   313篇
  1982年   270篇
  1981年   241篇
  1980年   235篇
  1979年   253篇
  1978年   243篇
  1974年   221篇
  1973年   203篇
  1972年   196篇
  1968年   192篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
We report on 7 patients (6 M, 1 F) with Coffin-Lowry syndrome who have a sensorineural hearing deficit in addition to developmental delay and characteristic facial changes. One of the patients also had a history of premature exfoliation of primary teeth. These are previously unappreciated clinical signs that may aid in the early diagnosis of Coffin-Lowry syndrome. Early diagnosis and recognition of a hearing deficit in the patient can lead to the use of hearing aids to help the patient achieve his or her full potential. These “;new”; clinical manifestations expand the phenotype of Coffin-Lowry syndrome and constitute an additional indication of pleiotropy. © 1993 Wiley-Liss, Inc.  相似文献   
72.
Objectives.To test the safety, efficacy, and toxicity of gene therapy using wild-type p53-expressing adenovirus (Ad-CMV-p53) in a nude mouse model with intraperitoneal (ip) 2774 human ovarian cancer cell line that contains a p53 mutation.Study design.An initial study of adenovirus tolerance was determined in nude mice by a single ip injection of increasing doses of Ad-CMV-p53. Nude mice were implanted with an LD100dose of 1 × 107cells. To study the efficacy and specificity of Ad-CMV-p53 treatment, the mice received treatment with different adenovirus constructs. One group received Ad-CMV-p53 and another group received a control adenovirus construct, Ad-CMV-βgal. To study the treatment response to Ad-CMV-p53, the mice were divided into groups and received various treatment schedules of 1 × 108pfu of Ad-CMV-p53.Results.The mice tolerated Ad-CMV-p53 without adverse effects at doses of 1 × 108pfu. The response to Ad-CMV-p53 showed significant survival duration in each dose regimen, with a survival time greater than that of untreated animals (P= 0.0173). However, no statistically significant survival advantage was observed between Ad-CMV-p53- and Ad-CMV-βgal-treated mice.Conclusions.These studies show that at the adenovirus dose and administration regimen used, there is effective but not specific 2774 tumor growth inhibitionin vivo.Efficient introduction of biologically active genes into tumor cells would greatly facilitate cancer therapy. Thus, although promising, these results caution that much effort will be required to realize the potential for clinical application of adenovirus-based ovarian cancer gene therapy.  相似文献   
73.
74.
Venous disease: investigation and treatment,fact or fiction?   总被引:1,自引:1,他引:0       下载免费PDF全文
This review looks at some clinical and experimental methods and treatments used in venous disease, and attempts to dispel some myths which have been associated with it. Over the last century numerous techniques have been introduced to aid the understanding of the physiology of normal legs and the pathophysiology of those with venous disease. Tourniquet testing along with clinical examination remains the only method of venous assessment in most hospitals. Venous ulceration in the past has been associated with deep vein incompetence, but the newer, non-invasive techniques of Doppler ultrasound and duplex examination are now identifying patients with leg ulceration who have superficial venous insufficiency and therefore a surgically correctable condition. Perforating veins and their possible role in the aetiology of venous ulceration along with invasive and non-invasive methods for their detection is reviewed. Some of the conservative compression treatments and dressings available for the treatment of venous ulceration are discussed. It is concluded that adherence to sound surgical principles remains the mainstay of the successful management of patients with venous disease.  相似文献   
75.
76.
Regulation of T cell-dependent immune responses is mediated in part by bone marrow-derived antigen presenting cells (APC) that (a) process and present antigens which engage the T cell receptor and (b) secrete cytokines that influence the threshold of T cell activation. The anterior chamber of the eye is lined by the corneal endothelium (which rests on a stroma and epithelium that is devoid of class II MHC + APC) and iris/ciliary body (which contain significant numbers of bone marrow-derived cells, one third of which are class II MHC +). When tested in vitro, these potential APCs fail to present antigens in a form that activates T cells. Moreover, iris/ciliary body cells actually suppress activation of T cells exposed to antigens on conventional APC. In addition, aqueous humor under normal circumstances contains factors (one of which is TGFB) that are potent inhibitors of antigen-driven T cell activation, but spare other aspects of T cell function. Evidence suggests that the bone marrow-derived cells in iris/ciliary body are the source of this factor. Thus, the anterior chamber contains powerful forces that can prevent induction and can suppress expression of T cell mediated immunity. It is proposed that these forces are responsible for immunologic privilege and anterior chamber associated immune deviation, and for suppressing pathologic proliferation and inflammation in the anterior segment of the eye.  相似文献   
77.
Epicardial antiarrhythmic drug administration was studied as a therapeutic approach for experimental ventricular tachycardia (VT) in an open-chest dog model. Lidocaine-polyurethane matrices (28%, w/w) were formulated as a model system. Matrices were placed on the left ventricular epicardium in each of 23 anesthetized open-chest dogs with ouabain-induced VT, to evaluate effectiveness in restoring sinus rhythm. Conversion occurred in all animals treated with matrices containing 300 mg or more of lidocaine after 1.5 to 7.0 min. The matrix lidocaine content correlated linearly with the time required for conversion to sinus rhythm (r = 0.75, P = 0.0002); irrespective of matrix size the myocardial/plasma lidocaine ratio was 20.1 ± 4.2 (mean ± SD) at the time of conversion. In a separate series of five dogs without ventricular tachycardia, systolic wall thickening measured with sonomicrometers after 5 min of controlled-release lidocaine administration (500- to 1000-mg matrix lidocaine content, 7.48 ± 3.49-mg/kg dose) was only minimally diminished (–14.1%) and this effect was observed only at the site of matrix placement on the anterior-apical epicardium. In contrast, intracoronary injection of 0.3 or 1.0 mg/kg of lidocaine-HCl resulted in complete elimination of wall thickening or replacement by systolic thinning. Thus epicardial administration of lidocaine from polyurethane matrices was an effective means of treating ouabain-induced ventricular tachycardia. Regional myocardial function in the vicinity of the matrices was modified to a very limited degree, supporting the view that the matrices can be used safely, without serious risk to ventricular contractile performance.  相似文献   
78.
Abstract. Twenty-one patients were studied at rest and during exercise after heart transplantation to compare cardiac output measured by thermodilution and impedance cardiography. Exercise was performed on a bicycle ergometer over a limited range of work load (25 and 50 watt) whilst metabolic gas exchange was recorded. One patient was studied at rest whilst his circulation was maintained by a Jarvik-7 artificial heart. The values of cardiac output measured by impedance cardiography corresponded closely with the flow rate from the artificial heart. There was also close agreement between the impedance and thermodilution measurements of cardiac output at rest and during exercise. Both measurements followed the changes in heart rate and oxygen consumption. Both thermodilution and impedance cardiography methods elicited good reproducibility of cardiac output measurements at rest and during exercise. These observations suggest that the noninvasive and continuous record of cardiac output obtained by impedance cardiography can be used for the postoperative monitoring of heart transplant recipients.  相似文献   
79.
80.
Oblique muscle palsies fixating with the paretic eye   总被引:1,自引:0,他引:1  
Palsy of the superior oblique muscle is one of the most commonly occurring entities in strabismus; the clinical characteristics are easily recognizable. Isolated inferior oblique muscle palsy, although anatomically enigmatical, is also known to ophthalmologists. When a patient with an oblique muscle palsy chooses to fixate with the paretic eye, characteristic patterns of motility may be obscured. Patients with superior oblique muscle palsy or isolated inferior oblique muscle palsy who habitually fixate with the paretic eye, may present with limited elevation or depression respectively. In each case, limited motility exists secondary to decreased innervational input to the contralateral antagonist of the paretic muscle, or to a mechanical restriction caused by prolonged contracture of the yoke of the paretic muscle. Inhibitional palsy of the contralateral antagonists and the fallen and rising eye syndromes may present diagnostic dilemmas unless the underlying oblique muscle palsy is recognized. Proper diagnosis may be obtained with three clinical tests; the 3-step test, the comparison of ductions to versions, and forced ductions.  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