全文获取类型
收费全文 | 19327篇 |
免费 | 812篇 |
国内免费 | 81篇 |
专业分类
耳鼻咽喉 | 175篇 |
儿科学 | 258篇 |
妇产科学 | 205篇 |
基础医学 | 2592篇 |
口腔科学 | 662篇 |
临床医学 | 1799篇 |
内科学 | 4001篇 |
皮肤病学 | 533篇 |
神经病学 | 2028篇 |
特种医学 | 1224篇 |
外科学 | 3047篇 |
综合类 | 90篇 |
一般理论 | 6篇 |
预防医学 | 887篇 |
眼科学 | 392篇 |
药学 | 992篇 |
1篇 | |
中国医学 | 52篇 |
肿瘤学 | 1276篇 |
出版年
2024年 | 113篇 |
2023年 | 154篇 |
2022年 | 287篇 |
2021年 | 547篇 |
2020年 | 386篇 |
2019年 | 457篇 |
2018年 | 543篇 |
2017年 | 436篇 |
2016年 | 588篇 |
2015年 | 661篇 |
2014年 | 804篇 |
2013年 | 1010篇 |
2012年 | 1579篇 |
2011年 | 1482篇 |
2010年 | 922篇 |
2009年 | 800篇 |
2008年 | 1316篇 |
2007年 | 1409篇 |
2006年 | 1304篇 |
2005年 | 1216篇 |
2004年 | 1093篇 |
2003年 | 991篇 |
2002年 | 874篇 |
2001年 | 169篇 |
2000年 | 107篇 |
1999年 | 164篇 |
1998年 | 156篇 |
1997年 | 135篇 |
1996年 | 80篇 |
1995年 | 52篇 |
1994年 | 41篇 |
1993年 | 45篇 |
1992年 | 43篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 24篇 |
1987年 | 14篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1974年 | 7篇 |
1973年 | 11篇 |
1970年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Davangere P Devanand Christian G Habeck Matthias H Tabert Nikolaos Scarmeas Gregory H Pelton James R Moeller Brett D Mensh Tyler Tarabula Ronald L Van Heertum Yaakov Stern 《Neuropsychopharmacology》2006,31(6):1327-1334
Temporoparietal and posterior cingulate metabolism deficits characterize patients with Alzheimer's disease (AD). A H(2)(15)O resting PET scan covariance pattern, derived by using multivariate techniques, was previously shown to discriminate 17 mild AD patients from 16 healthy controls. This AD covariance pattern revealed hypoperfusion in bilateral inferior parietal lobule and cingulate; and left middle frontal, inferior frontal, precentral, and supramarginal gyri. The AD pattern also revealed hyperperfusion in bilateral insula, lingual gyri, and cuneus; left fusiform and superior occipital gyri; and right parahippocampal gyrus and pulvinar. In an independent sample of 23 outpatients with mild cognitive impairment (MCI) followed at 6-month intervals, the AD pattern score was evaluated as a predictor of cognitive decline. In this MCI sample, an H2(15)O resting PET scan was carried out at baseline. Mean duration of follow-up was 48.8 (SD 15.5) months, during which time six of 23 MCI patients converted to AD. In generalized estimating equations (GEE) analyses, controlling for age, sex, education, and baseline neuropsychological scores, increased AD pattern score was associated with greater decline in each neuropsychological test score over time (Mini Mental State Exam, Selective Reminding Test delayed recall, Animal Naming, WAIS-R digit symbol; Ps<0.01-0.001). In summary, a resting PET covariance pattern previously reported to discriminate AD patients from control subjects was applied prospectively to an independent sample of MCI patients and found to predict cognitive decline. Independent replication in larger samples is needed before clinical application can be considered. 相似文献
2.
3.
4.
Reiner Mengel Matthias Eigenbrodt Thomas Schünemann Lavin Florès-de-Jacoby 《Journal of clinical periodontology》1996,23(5):437-443
Abstract From August to October 1991, the periodontal status of 1001 Yemenis representing the age groups 12-14, 15-19, 20-24 and 35-44 years was recorded and evaluated with preference to the CPITN, the calculus index and clinical attachment levels. The impact of chewing khat, the leaves of a cultivated, alkaloid shrub, and of using the traditional miswak chewing stick for oral hygiene purposes were investigated. The results show that 6.9% of the juvenile probands (15-19 years) had healthy periodontal tissue (CPITN 0). whereas bleeding on probing and calculus (CPITN 1+2) were registered in 86.2%. In the 35-44 year age group. 1.7% were periodontally healthy, whereas 84.5% displayed plaque retention or shallow pocketing (CPITN 2-3) and 12.5% deep pocketing (CPITN 4). The treatment needs in all age groups are confined primarily to calculus removal and instruction in oral hygiene. The clinical attachment level and the calculus index revealed age-related attachment loss and calculus formation, primarily among male probands. The higher khat consumption among the male population is reflected in its detrimental effect on the periodontal tissue, especially among younger probands. Oral hygiene aids have also an influence on periodontal status, with a toothbrush proving more efficient than the miswak. WHO efforts directed towards prophylactic programs need to be intensified but can be staffed by dental hygienists. 相似文献
5.
6.
Tibor Bartha Matthias Kalwitzki Claus L?st Roland Weiger 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2006,102(5):692-697
OBJECTIVE: The objective of this study was to compare 2 preparation techniques performed under simulated clinical conditions with extended apical enlargement following determination of the optimal apical preparation size (APS). STUDY DESIGN: After preflaring 240 root canals, APS was evaluated as outlined in Part I. The apical portion was shaped to APS either with rotary NiTi Lightspeed instruments (LS) or NiTi hand instruments (HA) using the balanced force technique in a phantom head. After sectioning the apical area at 3 levels, every cross section was analyzed microscopically for circumferential removal of canal wall dentine. Loss of working length, instrument separation, and perforation were additionally recorded. RESULTS: In 70% (LS) and 69% (HA) of the root canals, 2 of 3 levels demonstrated that the root canal dentin was cut circumferentially. Neither loss of working length nor perforation occurred in both groups. Four LS instruments separated. CONCLUSIONS: APS frequently results in a nearly complete apical preparation regardless of the preparation techniques. In a few cases apical enlargement to APS does not achieve complete cutting of the canal walls. There was a rather slight risk of serious procedural errors. 相似文献
7.
8.
9.
RiLSG Matthias Willersinn 《MedR Medizinrecht》2007,25(11):684-690
Ohne Zusammenfassung 相似文献
10.
Elektrophysiologische Untersuchungen (EPU) und programmierte Ventrikelstimulationen (PVS) werden vor der Implantation eines Defibrillators (ICD) empfohlen, wenn Patienten ohne nachweisbare strukturelle Herzerkrankung oder mit hypertrophischer obstruktiver Kardiomyopathie (HOCM) einen Herzstillstand überlebt haben, weil die Prävalenz von prinzipiell kurierbaren Rhythmusstörungen wie idiopathischen ventrikulären Tachykardien (VT), bei diesen Patienten hoch ist. Gleiches gilt für Patienten nach überlebtem Herzstillstand mit einer kurzen PQ-Zeit oder einer Deltawelle. Patienten mit Tachykardien, bei denen die Diagnose VT unsicher ist, sollten ebenfalls einer EPU unterzogen werden. Wenn sich Patienten mit nicht anhaltenden Tachykardien oder Synkopen vorstellen, sind eine EPU und PVS zur Risikostratifizierung indiziert. Bei den übrigen Patienten mit eingeschränkter linksventrikulärer Pumpfunktion nach überlebtem Herzstillstand oder instabiler VT, die Kandidaten für eine ICD-Implantation sind, haben die EPU und PVS möglicherweise nur einen geringen Nutzen. 相似文献