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   20489篇
  免费   1371篇
  国内免费   45篇
耳鼻咽喉   203篇
儿科学   555篇
妇产科学   452篇
基础医学   2605篇
口腔科学   321篇
临床医学   2319篇
内科学   4170篇
皮肤病学   238篇
神经病学   1882篇
特种医学   830篇
外国民族医学   27篇
外科学   3410篇
综合类   188篇
一般理论   13篇
预防医学   1649篇
眼科学   408篇
药学   1130篇
中国医学   24篇
肿瘤学   1481篇
  2023年   147篇
  2022年   323篇
  2021年   664篇
  2020年   365篇
  2019年   526篇
  2018年   617篇
  2017年   472篇
  2016年   508篇
  2015年   593篇
  2014年   829篇
  2013年   984篇
  2012年   1411篇
  2011年   1515篇
  2010年   808篇
  2009年   635篇
  2008年   1160篇
  2007年   1081篇
  2006年   1050篇
  2005年   954篇
  2004年   828篇
  2003年   800篇
  2002年   777篇
  2001年   351篇
  2000年   337篇
  1999年   305篇
  1998年   172篇
  1997年   135篇
  1996年   106篇
  1995年   101篇
  1994年   78篇
  1993年   92篇
  1992年   209篇
  1991年   199篇
  1990年   194篇
  1989年   173篇
  1988年   158篇
  1987年   140篇
  1986年   142篇
  1985年   146篇
  1984年   124篇
  1983年   93篇
  1982年   84篇
  1981年   74篇
  1979年   74篇
  1978年   76篇
  1977年   75篇
  1976年   67篇
  1975年   65篇
  1974年   81篇
  1973年   67篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
A patient with a surgically proven intracanalicular arachnoid cyst was studied using computed tomography, magnetic resonance imaging, and air CT cisternography. The lesion had a similar radiographic appearance to acoustic neuroma and therefore, although rare, must be considered in the differential diagnosis of intracanalicular mass lesions. We report a case in which examination was performed, in evaluating the lesion, utilizing high-resolution air CT cisternography and magnetic resonance imaging (MRI).  相似文献   
22.
23.
OBJECTIVES: To assess the results of a cooperative arrangement between Slovakia and Slovenia for neonatal cardiac surgery. The aim of the study was to analyze the performance of this approach for complete transposition of the great arteries (D-TGA). METHODS: Due to the overall small number of new patients with D-TGA in Slovenia a decision was made to avoid a prolonged learning curve by centralizing the experience of two countries at one center. Since 1995 the center in Slovakia has become the only referral center for Slovenia. Between February 1993 and June 2002 in this center, 147 patients with D-TGA underwent arterial switch operation (ASO). The median age at operation was 11 days, with 110 patients from Slovakia and 37 patients from Slovenia. RESULTS: Overall hospital mortality was 4.8% (seven patients). The 1, 2, 3, 4 and 5 year survival rate was 95% with the mean follow-up of 4 years. Operation before 1997 (P=0.0001) was identified as a risk predictor for death by multivariate analysis. There are no deaths among the 90 patients operated on after 1996. All patients are without medication with normal left ventricular function. Stenosis (gradient >30 mmHg) was noted in the pulmonary artery reconstruction in seven patients (5%). More than mild aortic regurgitation was noted in five patients (4%). The incidence of redo or reintervention was 5% at 5 years of follow-up. CONCLUSIONS: In the current era a prolonged learning curve for ASO is not acceptable to most European countries and their patients. The risk of surgery can be minimized by concentrating surgical experience as part of the quality control of congenital heart programs. If the number of new patients is small due to the birth rate and size of the population, institutions should merge activity. Such centralization amplifies the experience to the benefit of the patient.  相似文献   
24.
25.
Tests of grating acuity often underestimate amblyopia and underrefer esotropic infants with a fixation preference. To evaluate the effect of the large grating field used in preferential looking (PL) procedures, an eight-alternative, small field (about 1 degrees) grating acuity test was devised. Gratings contained at least eight cycles. Thirty-seven strabismic and/or anisometropic amblyopes, ages 3-13 yr, were tested. In most amblyopic eyes, grating acuities were better than recognition acuities; the difference was reduced, however, in the small field test compared to the large field (6 degrees test (means, 1 oct vs. 1.6 oct; paired-t = 5.5, P less than .001). Nevertheless, the same relation between grating and recognition acuities occurred for small as for large fields: an increased discrepancy between grating and recognition acuities accompanied poorer acuity. This larger discrepancy is attributed to increased probability summation of amblyopic eyes for low spatial frequencies. For preschool children who can be tested by both procedures, the eight-alternative grating acuity test may be preferable to operant PL because it is more easily administered and materials are simpler.  相似文献   
26.
1. The pharmacokinetics of Dalal-peptide T-NH2 (peptide T) was determined during phase I clinical trials in patients with acquired immunodeficiecy disease (AIDS) and AIDS related complex (ARC). Drug levels were determined by specific RIA, and in some cases with HPLC analysis, after intraveneous (i.v.) or intranasal (i.n.), via metered sprayer, administration.

2. The plasma kinetics appeared to be bi-phasic with a first compartment half-life of 30 to 60 minutes and a second plasma clearence rate of 4 to 6 hours, observed for both routes of administration. Peptide T, in one individual was confirmed to be present at 6 hrs in plasma, determined after HPLC isolation followed by specific RIA.

3. Bioavailabilty, determined for a 2 mg test dose in six individuals was 9.3 ± 6.9 nmol/L. Peak plasma levels of 41 ± 30 nmol/L after 10 mg i.n., 2.8 ± 5.9 nmol/L after 2mg i.n., and 0.13 ± 0.07 nmol/L after 0.4 mg i.n. were observed. In two individuals tested, peptide T was detected in CSF at levels 20% of the corresponding plasma level 90 and 145 minutes post i.v. administration. Peptide T was not detected in urine. I.N. administration was well tolerated for times up to 21 months.  相似文献   

27.
28.
Stroke is a major health problem worldwide, causing high morbidity and mortality. Intracerebral hemorrhage (ICH) accounts for 15% of stroke cases in the US and Europe and up to 30% in Asian populations. It is less treatable than other forms of stroke and causes higher morbidity and disability. Data suggest that early hematomy growth is the principal cause of early neurological deterioration after ICH. Prospective and retrospective studies indicate that early hematoma growth occurs in 18–38% of patients scanned within 3 h of ICH onset, and that hematoma volume is an important predictor of 30-day mortality. As hematoma growth in acute ICH is a dynamic process, intervention with ultra-early hemostatic therapy could lead to minimization and even prevention of early hematomy growth. Recombinant activated factor VII (rFVIIa, ‘NovoSeven’), a powerful initiator of hemostasis, is approved for the treatment of bleeding in patients with hemophilia and inhibitors and may also promote hemostasis in patients with normal coagulation. rFVa acts locally at the bleeding site without activating systemic coagulation and may be a valuable therapy during the hyperacute stage of ICH. A randomized, double-blind, placebo-controlled, dose-ranging trial is currently in progress to investigate the potential of rFVIIa as an ultra-early hemostatic therapy to prevent or minimize hematoma growth in ICH patients without coagulopathy.  相似文献   
29.
30.
Zusammenfassung Die neurodegenerativen Erkrankungen bestehen aus einer Gruppe heterogener, progredient verlaufender Erkrankungen unterschiedlicher Ätiologie, die ein oder mehrere Systeme beeinträchtigen. Sie treten überwiegend im höheren Lebensalter auf, in dem sich zusätzlich sowohl die Art wie auch das Ausmaß des Schlafes ändern. Die neurodegenerativen Prozesse verursachen strukturelle Veränderungen der Schlaf-Wach-Generatoren im Hirnstamm, die Schlafstörungen wie Tagesschläfrigkeit, Insomnie, nächtliche bewegungs- und schlafbezogene Atmungsstörungen sowie Störungen des zirkadianen Schlaf-Wach-Rhythmus zur Folge haben können. Bei manchen neurodegenerativen Erkrankungen sind im Vorfeld der Krankheitsmanifestation auftretende Schlafstörungen bereits Krankheitsprädiktoren. Polysomnographisch finden sich Schlaffragmentierung, tonische oder phasische Beinbewegungen, Störungen der Atemmuskulatur, verminderter Tiefschlaf, Abwesenheit von REM-Schlaf oder REM-Schlaf ohne Muskelatonie, vermehrte Arousal- und Weckreaktionen, epileptiforme EEG-Aktivität oder schlafbezogene Atmungsstörungen. Sehr häufig sind REM-Schlaf-Verhaltensstörungen assoziiert mit neurodegenerativen Erkrankungen. In dieser Übersichtsarbeit werden Symptomatik, Pathophysiologie und polysomnographische Befunde von Schlafstörungen häufiger neurodegenerativer Erkrankungen vorgestellt.  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