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   3015篇
  免费   134篇
  国内免费   7篇
耳鼻咽喉   59篇
儿科学   67篇
妇产科学   32篇
基础医学   605篇
口腔科学   158篇
临床医学   351篇
内科学   518篇
皮肤病学   119篇
神经病学   210篇
特种医学   119篇
外科学   347篇
综合类   29篇
预防医学   161篇
眼科学   62篇
药学   200篇
中国医学   4篇
肿瘤学   115篇
  2022年   30篇
  2021年   58篇
  2020年   31篇
  2019年   37篇
  2018年   29篇
  2017年   35篇
  2016年   39篇
  2015年   56篇
  2014年   55篇
  2013年   74篇
  2012年   115篇
  2011年   116篇
  2010年   60篇
  2009年   78篇
  2008年   136篇
  2007年   146篇
  2006年   151篇
  2005年   152篇
  2004年   117篇
  2003年   161篇
  2002年   135篇
  2001年   109篇
  2000年   101篇
  1999年   99篇
  1998年   26篇
  1997年   37篇
  1996年   26篇
  1995年   20篇
  1993年   20篇
  1992年   51篇
  1991年   37篇
  1990年   48篇
  1989年   54篇
  1988年   38篇
  1987年   32篇
  1986年   34篇
  1985年   33篇
  1984年   22篇
  1979年   20篇
  1976年   21篇
  1974年   24篇
  1973年   21篇
  1972年   21篇
  1970年   22篇
  1885年   18篇
  1880年   32篇
  1879年   21篇
  1877年   21篇
  1876年   21篇
  1875年   18篇
排序方式: 共有3156条查询结果,搜索用时 15 毫秒
51.
52.
It is reported on the results of a comparative examination of 18 patients with two usual ergometric methods (team pathophysiology of respiration and research group diseases of heart and circulation of the GDR). Referred to the intake of oxygen as a measure for the stress of the cardiorespiratory system by means of the ergometric methods recommended by the research group diseases of heart and circulation significantly higher minute volumes of the heart rate were established. Principal differences in the evidence of the two methods did not appear.  相似文献   
53.
54.
Thirty consecutive patients with globus sensation who were referred to a psychosomatic clinic prospectively underwent otolaryngological, videokinematographic, and manometric examinations of pharynx and esophagus to evaluate whether morphological abnormalities or motility disorders underlay their symptom. When indicated by findings, 24-hour pH-metry, scintigraphy of bolus transport, and esophagogastroscopy were performed. Seven patients were shown to have achalasia, 10 had "hypochalasia" (lower esophageal sphincter relaxation less than 75% with esophageal contraction abnormalities but no complete distal aperistalsis), and 1 had diffuse esophageal spasms; 2 patients had also hyperplastic lingual tonsils, 1 had tonsillitis, and 1 had a cervical spondylophyte. Nutcracker esophagus and nonspecific contraction abnormalities were found in 7 patients, and gastroesophageal reflux with esophagitis and a low lower esophageal sphincter resting pressure was found in 1; only 3 patients had normal esophageal motility. None had volunteered dysphagic symptoms at primary evaluation. Psychometric investigations in consenting patients showed no higher mean scores for state and trait anxiety, depression, hysteria, and hypochondriasis than in general medical outpatients. Esophageal motor disorders may, before giving rise to dysphagia, be sensed more vaguely and induce the globus sensation. However, only disappearance of the sensation after treatment allows inferring an etiological significance of such a disorder.  相似文献   
55.
56.
Recent investigations have shown that N‐ethyl‐N‐cyclopropyl lysergamide (ECPLA) produces LSD‐like behavioral effects in mice, which suggests that it may act as a hallucinogen in humans. Although the use of ECPLA as a recreational drug has been limited, key analytical data that can be used to detect ECPLA are required for future forensic and clinical investigations. ECPLA is an isomer of (2′S,4′S)‐lysergic acid 2,4‐dimethylazetidide (LSZ), a lysergamide that emerged as a recreational drug in 2013. Several analytical approaches were examined, including single‐ and tandem mass spectrometry platforms at low and high resolution, gas‐ and liquid chromatography (GC, LC), nuclear magnetic resonance spectroscopy (NMR), and GC condensed‐phase infrared spectroscopy (GC‐sIR). ECPLA and LSZ could be differentiated by NMR, GC‐sIR, GC, and LC‐based methods. The electron ionization mass spectra of ECPLA and LSZ contained ion clusters typically observed with related lysergamides such as m/z 150–155, m/z 177–182, m/z 191–197, m/z 205–208, and m/z 219–224. One of the significant differences in abundance related to these clusters included ions at m/z 196 and m/z 207/208. The base peaks were detected at m/z 221 in both cases followed by the retro‐Diels‐Alder fragment at m/z 292. Minor but noticeable differences between the two isomers could also be seen in the relative abundance of m/z 98 and m/z 41. Electrospray ionization mass spectra included lysergamide‐related ions at m/z 281, 251, 223, 208, 197, 180, and 140. LSZ (but not ECPLA) showed product ions at m/z 267 and m/z 98 under the conditions used.  相似文献   
57.
Lysergic acid diethylamide (LSD) is a prototypical serotonergic psychedelic drug and the subject of many clinical investigations. In recent years, a range of lysergamides has emerged with the production of some being inspired by the existing scientific literature. Others, for example various 1‐acyl substituted lysergamides, did not exist before their appearance as research chemicals. 1‐Cylopropanoyl‐LSD (1CP‐LSD) has recently emerged as a new addition to the group of lysergamide‐based designer drugs and is believed to be psychoactive in humans. In this investigation, 1CP‐LSD was subjected to detailed analytical characterizations including various mass spectrometry (MS) platforms, gas and liquid chromatography, nuclear magnetic resonance spectroscopy, solid phase and GC condensed phase infrared spectroscopy. Analysis by GC–MS also revealed the detection of artificially induced degradation products. Incubation of 1CP‐LSD with human serum led to the formation of LSD, indicating that it may act as a prodrug for LSD in vivo, similar to other 1‐acyl substituted lysergamides. The analysis of blotters and pellets is also included. 1CP‐LSD also induces the head‐twitch response (HTR) in C57BL/6 J mice, indicating that it produces an LSD‐like behavioural profile. 1CP‐LSD induced the HTR with an ED50 = 430.0 nmol/kg which was comparable to 1P‐LSD (ED50 = 349.6 nmol/kg) investigated previously. Clinical studies are required to determine the potency and profile of the effects produced by 1CP‐LSD in humans.  相似文献   
58.
In this article, we describe a case of left ventricular assist device endocarditis caused by a vancomycin-intermediate Staphylococcus aureus strain that was successfully treated with ceftaroline. Left ventricular assist device infections are briefly reviewed, and the current knowledge regarding vancomycin resistance is discussed.  相似文献   
59.
Objectives:To assess quantitatively the combined effect of exomass-related- and motion artefacts on voxel value parameters in cone beam CT (CBCT).Methods:A cylindrical phantom was manufactured, containing 21 tubes filled with a radiopaque solution, allowing the inclusion of three titanium implants in the periphery to induce exomass-related artefacts. The phantom was mounted on a robot simulating 0.75-, 1.5-, and 3 mm movements (nodding/lateral rotation/tremor). CBCT images with/without exomass and with/without movements were acquired in duplicate in three units: Cranex 3Dx, Orthophos SL-3D, and X1 (with motion-artefact correction). A cylindrical volume of interest was defined in each tube and voxel value mean and standard deviation were assessed. For each CBCT volume, the 21 mean voxel values were averaged providing the overall mean voxel value (MVV), and the standard deviation (among the 21 values) was calculated providing overall voxel value inhomogeneity (VVI). The standard deviation from each of the 21 volumes-of-interest were averaged, providing overall image noise (IN). The effect of the diverse tested situations was inferred from a repeated-measures analysis of variance, followed by Sidak’s test (α = 0.05).Results:Overall, images acquired with exomass showed significantly (p ≤ 0.05) lower MVV, and higher VVI and IN. Motion artefacts aggravated exomass-related alterations. MVV and VVI were mostly affected by 3 mm nodding movements. Motion-artefact correction eliminated the deleterious effect of movement.Conclusions:CBCT voxel-value parameters are altered by exomass-related artefacts, and this finding is aggravated in the presence of motion artefacts. Motion-artefact correction effectively eliminated the deleterious impact of movement.  相似文献   
60.
The International Journal of Cardiovascular Imaging - To evaluate the prevalence of aortic regurgitation (AR) and associations between the individual aortic root components and AR severity in the...  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