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   3873篇
  免费   339篇
  国内免费   9篇
耳鼻咽喉   32篇
儿科学   148篇
妇产科学   70篇
基础医学   588篇
口腔科学   160篇
临床医学   551篇
内科学   672篇
皮肤病学   57篇
神经病学   341篇
特种医学   117篇
外科学   462篇
综合类   26篇
预防医学   438篇
眼科学   42篇
药学   336篇
中国医学   11篇
肿瘤学   170篇
  2023年   50篇
  2022年   62篇
  2021年   130篇
  2020年   107篇
  2019年   116篇
  2018年   179篇
  2017年   178篇
  2016年   149篇
  2015年   153篇
  2014年   210篇
  2013年   351篇
  2012年   275篇
  2011年   296篇
  2010年   232篇
  2009年   140篇
  2008年   141篇
  2007年   131篇
  2006年   102篇
  2005年   107篇
  2004年   98篇
  2003年   61篇
  2002年   55篇
  2001年   39篇
  2000年   36篇
  1999年   36篇
  1998年   50篇
  1997年   47篇
  1996年   33篇
  1995年   36篇
  1994年   24篇
  1993年   22篇
  1992年   43篇
  1991年   30篇
  1990年   24篇
  1989年   20篇
  1988年   35篇
  1987年   24篇
  1986年   16篇
  1985年   25篇
  1984年   30篇
  1983年   20篇
  1982年   35篇
  1981年   33篇
  1980年   27篇
  1979年   13篇
  1978年   19篇
  1976年   12篇
  1974年   17篇
  1973年   18篇
  1972年   12篇
排序方式: 共有4221条查询结果,搜索用时 15 毫秒
1.
2.
背景:浴光疗同步治疗银屑病的有效性与UVB和死海盐的多靶点作用有关,同步治疗能够起到协同功效。目的:本回顾性研究的目的:①评价浴光疗同步治疗各种临床类型银屑病的有效性;②观察治疗反应有无不同;③获得更多数据以预测对不同类型银屑病的治疗效果,以便针对患者的类型选择治疗效果良好的方法。方法:根据Regensburg计划,患者接受了一个包括35次治疗的基础同步浴光疗疗程,随后又接受了一个包括25次治疗的维持治疗疗程。治疗中每周进行PASI评分以评价患者的皮肤状态。对373例按计划完成基础疗程的患者和其中78例完成维持疗程的患者的治疗…  相似文献   
3.
Objective: The primary aim of this study was to investigate whether bioequivalence is achieved for a new fixed combination of extended-release (ER) felodipine and controlled-release (CR/ZOK) metoprolol␣compared with the free combination of felodipine ER metoprolol CR/ZOK. The second aim was to study whether there was an interaction in pharmacokinetics and pharmacodynamics between felodipine and metoprolol when administered as ER formulation. Methods: Two four-way cross-over studies were performed in 36 young subjects and 24 elderly subjects with frequent measurement of drug plasma concentrations, blood pressures and heart rate. The pharmacokinetic analysis included enantioselective analysis in six subjects. Results: Bioequivalence between the fixed combination and the free combination was observed for the two drugs (mean difference 27%) except for a minor deviation regarding Cmax of metoprolol in the elderly. No significant interaction was shown except for a small increase (6%) of metoprolol AUC in the younger subjects. Mean plasma S-/R-enantiomer ratios were almost identical for the different treatments. Blood pressure and heart rate was significantly reduced for the fixed combination compared with felodipine ER in the younger and the elderly subjects. No significant difference regarding pharmacodynamics was detected between the fixed combination and the corresponding free combination. Conclusion: The fixed combination consistently provides fairly constant and effective felodipine and metoprolol concentrations after once-daily administration of one tablet. It is clinically interchangeable with the free combination of metoprolol CR/ZOK tablets and felodipine ER tablets. Finally, felodipine and metoprolol do not interact on a pharmacokinetic level when administered as the fixed combination. Received: 29 October 1996 / Accepted in revised form: 21 March 1997  相似文献   
4.
Congenital “healed” cleft lip (CHCL) is an unusual anomaly including a paramedian “scar” of the upper lip, which appears as if a typical cleft lip has been corrected in utero. The CHCL is frequently associated with an ipsilateral notch in the vermilion, and “collapsed” nostril. Twenty-five CHCL cases are presented, eighteen of which were an isolated malformation found among the 3,950,715 births examined in two similar birth defect registries: ECEMC in Spain and ECLAMC in Latin America. Like open cleft lip, of which it seems to be a variant, CHCL is most frequently seen among males (14/18 isolated cases), it preferentially affects the left side (10/18 cases), and it segregated together with cleft lip in one family. The five CHCL cases with other congenital anomalies included: two cases with hydrocephalus, two VACTERL associations, and one atypical oblique facial cleft infant with single umbilical artery. CHCL may result from a defective fusion of the frontonasal and maxillary processes (before week 7 of embryonic life), or from a spontaneously repaired open cleft lip, later on. In either way, these cases heal with a visible scar, and the pre-occurrence of CHCL in two families suggests a familial predisposition to this phenomenon. © 1995 Wiley-Liss, Inc.  相似文献   
5.
BACKGROUND: Deposition of proteins on surfaces of medical devices has been recognized to putatively relate to the process of regulation of biomaterial-associated complications by attachment of fibrin clots, eukaryotic cells, and microbes. The molecules adsorb to a varying extent, depending not only on the physicochemical properties of the biomaterial, but also on the composition of the host fluid. OBJECTIVE: Adsorption of proteins on catheters exposed both ex vivo and in vitro to dialysate of patients on peritoneal dialysis (PD) was studied. METHODS: Peritoneal dialysis effluent was collected from 5 patients with end-stage renal disease on continuous ambulatory PD. Tenckhoff catheters were obtained from 16 patients. Deposition of proteins on excised Tenckhoff catheters and tubing of different materials exposed to PD effluent in vitro was studied using 125iodine-labeled antibodies. Adhesion of Staphylococcus aureus and Staphylococcus epidermidis strains was quantified on tubing exposed to PD effluent in vitro. RESULTS: The presence of albumin, transferrin, immunoglobulin G, fibrinogen, fibronectin, von Willebrand factor, vitronectin, and thrombospondin was determined at various concentrations in PD effluent. All proteins analyzed were detected on PD catheters removed from patients. The extent of protein deposition on Tenckhoff catheters exposed to PD effluent, in vitro, rapidly reached a plateau and remained constant, as it did on polyvinyl chloride and polyethylene tubing. Adhesion of staphylococci was enhanced on Tenckhoff catheters exposed to PD effluent compared to unused PD solution. CONCLUSIONS: The data identify surface exposed proteins that may serve as adhesion sites for microbes on peritoneal catheters indwelled in patients undergoing PD.  相似文献   
6.
Submitral ventricular aneurysm is a thoroughly studied pathology but is not well known due to its rarity. Clinically, it is manifested by symptoms and signs of heart failure, mitral regurgitation and/or ventricular arrhythmias, and may be associated with thromboembolic phenomena and myocardial ischemia due to compression of the coronary arteries by the aneurysm. A rare complication of this type of aneurysm is rupture into the left atrium. Transthoracic echocardiography plays an important role in the definitive diagnosis of this pathology, although the role of transesophageal echocardiography in the evaluation of these patients is less known. We report a case of a submitral ventricular aneurysm complicated by rupture into the left atrium, which was diagnosed by transesophageal echocardiography.  相似文献   
7.
The aim of this study was to investigate markers of serotonin and immune function in suicidal patients. Cytotoxic activity of natural killer cells (NK) and CD16 lymphocytes were studied in 28 suicide attempters and 26 healthy controls, and related in patients to 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF). Patients with CSF 5-HIAA below the median had significantly lower NK cell activity than other patients. CD16 cell frequency was significantly lower in patients than in controls, and patients also tended to have lower NK cell cytotoxicity than healthy controls. There were no statistically significant correlations between 4-hydroxy-3methoxyphenyl glycol (HMPG), homovanillic acid (HVA), CSF cortisol and NK cell activity. The results support the hypothesis of compromised immune function in suicidal patients with evidence of disordered serotonin function.  相似文献   
8.
9.
Serial sections of formalin-fixed, paraffinembedded blocks from two asymptomatic, non-AIDS cases of progressive multifocal leukoencephalopathy (PML) were stained with a double-label immunocytochemical method for detection of glial fibrillary acidic protein and JC virus (JCV) capsid proteins and with luxol fast blue/hematoxylin-eosin. In case 1 small, rounded lesions of about 1-mm diameter were seen within a restricted area in the posterior part of the superior frontal gyrus of both cerebral hemispheres, suggesting an early manifestation of the disease. Fully developed demyelinated lesions of the classical type with JCV-infected oligodendrocytes appeared in the white matter and along its border with the cortex. Lesswell-developed lesions, believed to be precursors to the fully developed ones, were seen in the gray and white matter. Of special interest were areas which contained small collections of enlarged, glial fibrillary acidic protein (GFAP)-positive astrocytes without capsid antigen and which seemed to lack destruction of myelin as judged from the appearance of matching serial sections stained for myelin. Large lesions in the brain of case 2 showed the well-known features of advanced PML. The close relation between some astrocytes and oligodendrocytes with viral antigen raises the possibility of early intercellular passage of virus. Vacuolation, seen within or near lesions in both cases, has previously been noted in the CNS infected by HIV, but not in PML. It is suggested that PML, a disease of both oligodendrocytes and astrocytes, may actually begin in astroglial cells which, under the influence of a restricted JCV infection, become reactive, express GFAP and pass on virus to the more highly susceptible oligodendrocytes with which they are in contact.Supported in part by a grant N.S.07596 from the National Institute of Neurological Disorders and Stroke. The work was carried out in the Laboratory of Experimental Neurophathology, NINDS, and in the Department of Pathology II, Karolinska Institute, Stockholm  相似文献   
10.
A series of positron emission tomography scans was made on two monkeys during a 16-month period when they received manganese(IV)oxide by subcutaneous injection. The distribution of [11C]-nomifensine uptake, indicating dopamine terminals, was followed in both monkey brains. The brain distributions of [11C]-raclopride, demonstrating D2 dopamine receptors, and [11C]-l-dopa, as a marker of dopamine turnover, were followed in one monkey each. The monkeys developed signs of poisoning namely unsteady gait and hypoactivity. The [11C]-nomifensine uptake in the striatum was reduced with time and reached a 60% reduction after 16 months exposure. This supports the suggestion that dopaminergic nerve endings degenerate during manganese intoxication. The [11C]-l-dopa decarboxylation was not significantly altered indicating a sparing of [11C]-l-dopa decarboxylation during manganese poisoning. A transient decrease of [11C]-raclopride binding occurred but at the end of the study D2-receptor binding had returned to starting values. The magnetic resonance imaging (MRI) revealed that the manganese accumulated in the globus pallidus, putamen and caudate nucleus. There were also suggestions of gliosis/edema in the posterior limb of the internal capsule. MRI might be useful to follow manganese intoxication in humans as long as the scan is made within a few months of exposure to manganese, i. e. before a reversal of the manganese accumulation.  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