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   13955篇
  免费   1055篇
  国内免费   28篇
耳鼻咽喉   200篇
儿科学   329篇
妇产科学   226篇
基础医学   1783篇
口腔科学   325篇
临床医学   1258篇
内科学   3001篇
皮肤病学   244篇
神经病学   1303篇
特种医学   529篇
外科学   2314篇
综合类   225篇
一般理论   13篇
预防医学   1083篇
眼科学   385篇
药学   783篇
中国医学   8篇
肿瘤学   1029篇
  2022年   87篇
  2021年   181篇
  2020年   124篇
  2019年   211篇
  2018年   230篇
  2017年   170篇
  2016年   185篇
  2015年   269篇
  2014年   356篇
  2013年   650篇
  2012年   781篇
  2011年   881篇
  2010年   453篇
  2009年   428篇
  2008年   877篇
  2007年   945篇
  2006年   904篇
  2005年   981篇
  2004年   869篇
  2003年   856篇
  2002年   844篇
  2001年   150篇
  2000年   117篇
  1999年   131篇
  1998年   196篇
  1997年   146篇
  1996年   142篇
  1995年   135篇
  1994年   116篇
  1993年   112篇
  1992年   87篇
  1991年   93篇
  1990年   76篇
  1989年   73篇
  1988年   98篇
  1987年   63篇
  1986年   78篇
  1985年   68篇
  1984年   94篇
  1983年   99篇
  1982年   126篇
  1981年   123篇
  1980年   122篇
  1979年   77篇
  1978年   80篇
  1977年   85篇
  1976年   83篇
  1975年   69篇
  1974年   62篇
  1973年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Zusammenfassung Bei der Bündelhaar-Follikulitis (tufted hair folliculitis) handelt es sich um eine durch Staphylococcus aureus verursachte, chronisch entzündliche und vernarbende Haarbodenerkrankung, die charakterisiert ist durch das umschriebene Auftreten von Bündelhaaren. Histopathologisch findet sich eine perifollikul?re Entzündung im oberen Bereich der Haarfollikel unter Aussparung der tiefen Follikelanteile. Innerhalb der Entzündungsareale münden mehrere Haare aus getrennten Haarwurzeln in ein gemeinsames Infundibulum mit dilatiertem Ostium. Das Krankheitsbild ist als eine Erscheinungsform der Folliculitis decalvans capillitii Quinquaud anzusehen, bei der die Auffassung besteht, da? die Infektion mit Staphylococcus aureus den pathogenetischen Initialfaktor darstellt, und Besonderheiten der Follikelanatomie und Immunantwort die individuelle Morphologie bestimmen: Dabei ist anzunehmen, da? die Ausbildung fl?chig atropher Narben mit vollst?ndigem Untergang der Hautanhangsgebilde (im Falle der Folliculitis decalvans) oder das Auftreten von Haarbündeln (im Falle der Bündelhaar-Follikulitis) von der Tiefe und dem Destruktions-Potential des Entzündungsinfiltrates abh?ngen. Die Behandlung der Bündelhaar-Follikulitis ist nicht ganz unproblematisch: Die prolongierte und wiederholte Gabe staphylokokken-wiksamer Antibiotika vermag den Krankheitsverlauf zu stabilisieren. Bereits vorhandene Haarbündel mit einer besonders hohen Rezidivneigung sollten aber – wie im vorgestellten Fall – nach M?glichkeit chirurgisch exzidiert werden.
Summary A case of tufted hair folliculutis presenting as circumscribed, tender and inflamed areas in the occiput with residual tufted follicles in a 28-year old man is reported. Tufted hair folliculitis is a characteristic localized scarring bacterial folliculitis of the scalp due to Staphylococcus aureus. Histopathological studies reveal perifollicular inflammation around the upper portions of the follicles sparing the hair root level. Within areas of inflammation, several follicles converge toward a common follicular duct with a widely dilated opening. Currently, tufted hair folliculitis is considered a variant of folliculitis decalvans of Quinquaud. Staphylococcal infection is believed to be an initial causative factor, and underlying differences in follicular anatomy or host response may be important in determining which reaction pattern occurs in an affected individual. The development of atrophy with loss of adnexal structures (in folliculitis decalvans) or of hair tufts (in tufting folliculitis) may depend upon the depth and destructive potential of the inflammatory process. The therapeutic approach is problematic; prolonged treatment with oral antibiotics may stabilize the disease, but good and at times more definitive results (as in the presented case) have been reported after radical surgical excision of the involved areas.
Eingegangen am 2. April 1996 Angenommen am 7. Juni 1996  相似文献   
62.
Phase I trial of piroxicam in 62 dogs bearing naturally occurring tumors   总被引:3,自引:0,他引:3  
Summary Piroxicam, a nonsteroidal antiinflammatory drug, was given to 62 dogs bearing naturally occurring tumors in a phase I clinical trial. Dose escalation was performed, with oral doses ranging from 0.5 mg/kg every 48 h (q48h) to 1.5 mg/kg q48h being tested. Dose-limiting gastromestinal irritation/ulceration occurred in all four animals that received 1.5 mg/kg q48h. The maximum tolerated dose was 1 mg/kg q48h. Subclinical renal papillary necrosis occurred in two dogs (initial dosages, 1 and 1.5 mg/kg q48h, respectively). Following dose escalation, an additional group of dogs was treated with 0.3 mg/kg piroxicam q24h per os, the accepted canine dosage prior to this trial. Inclusion of this treatment group enabled evaluation of the toxicity of and tumor response to a daily dosage regimen. No complete remissions occurred in this trial. Partial remission was documented in three of ten dogs exhibiting transitional-cell carcinoma, in three of five animals bearing squamous-cell carcinoma, in one of three dogs displaying mammary adenocarcinoma, and in the one dog that exhibited a transmissible venereal tumor. The results of this study support the additional evaluation of piroxicam in a phase II clinical trial in dogs bearing naturally occurring tumors.This investigation was supported by Pfizer Inc.  相似文献   
63.
64.
65.
In surveys of 4860 middle-aged men in Caerphilly (South Wales) and Speedwell (Bristol) alcohol consumption has been related to high density lipoprotein (HDL) cholesterol and its major subfractions, HDL2 and HDL3, measured in a single fasting blood sample. The results confirm that high density lipoprotein cholesterol concentration increases as the amount of alcohol regularly consumed increases. The relationship appears to be linear and is independent of age, smoking habit, body mass index, low density lipoprotein cholesterol and plasma total triglyceride. This rise in HDL cholesterol is not mediated through either HDL2 cholesterol or HDL3 cholesterol alone. Both subclasses increase significantly and by similar amounts with increasing alcohol intake.  相似文献   
66.
The selection of a healthcare information system is analogous to a big game hunt. The buyers perceive themselves as the hunters while the truth is just the opposite. To strip away the carefully crafted facade of corporate marketing is an art form and requires due diligence on the part of the shopper. Suggestions are offered to the consumer on how to pierce the shell of corporate silence and find the facts that will make a significant difference in product selection. The objectives on the seller's side are to make as much profit as possible and give as little as required to make the sale. The buyer is looking for the best product, the best company, and the most painless installation. The ground between these two vastly different goals is the battlefield of healthcare computer procurement. May the best shopper win! Caveat emptor.  相似文献   
67.
OBJECTIVES: Determine the resorption rate and biocompatibility characteristics of 2 polyester ventilation tubes, and to determine whether soap and water exposure accelerates polyester tube degradation. STUDY DESIGN AND SETTING: 50/50 poly (D, L-lactide-co-glycolide; PLGA-50) and poly (L-lactide; PLA) polymers were placed into the tympanic membranes of Hartley pigmented guinea pigs. Integrity of the tubes was determined by weekly otoscopic examination. Biocompatibility was assessed by comparing auditory brainstem response (ABR) thresholds and by examining tympanic membrane changes following tube resorption. Shah minigrommet ventilation tubes were used as controls. In the second portion of this study, implanted PLGA-50 and PLA tubes were exposed weekly to a mixture of soap and water (1:5) until complete resorption was observed. Biocompatibility was assessed by periodic ABR testing and tympanic membrane examination. RESULTS: The PLA tubes remained in the tympanic membrane for a longer period (63.2 +/- 19.3 days) than the PLGA-50 (18.8 +/- 8.1 days). The tympanic membrane and resorbable tube interface demonstrated equivalent findings for auditory thresholds and tissue histopathology at the implant site compared to nonresorbable controls. The resorption behavior was not altered by exposure to soap and water. Tympanic membranes of all animals following tube degradation and soap water exposure were intact with minimal scarring and no signs of persistent foreign body response. The histological analysis showed that implantation of resorbable tubes was not accompanied by secondary infection with otorrhea through the tube, did not result in a permanent perforation or dislocation of the tube into the middle ear cavity, and was not followed by excess tympanosclerosis or localized or diffuse membrane atrophy. CONCLUSIONS AND SIGNIFICANCE: Resorbable polyester pressure equalization tubes demonstrate predictable resorption behavior and similar biocompatibility characteristics when compared with nonresorbable Shah minigrommet ventilation tubes. Exposure to soap water does not accelerate polyester tube degradation nor change the host tissue response during the indwelling period or after complete resorption. The data suggests that resorbable ventilation tubes are substantially equivalent to other FDA-approved tympanostomy devices with regard to safety and biocompatibility in the guinea pig model examined and may provide improved clinical performance by combining this approach with sustained release technology. EBM RATING: B-2.  相似文献   
68.
69.
BACKGROUND: The WHO Foundation Collaborating Centre for International Drug Monitoring (Uppsala Monitoring Centre [UMC]) has received many individual case safety reports (ICSRs) associating HMG-CoA reductase inhibitor drug (statin) use with the occurrence of muscle damage, including rhabdomyolysis, and also peripheral neuropathy. A new signal has now appeared of disproportionally high reporting of upper motor neurone lesions. AIM AND SCOPE: The aim of this paper is to present the upper motor neurone lesion cases, with other evidence, as a signal of a relationship between statins and an amyotrophic lateral sclerosis (ALS)-like syndrome. The paper also presents some arguments for considering that a spectrum of severe neuromuscular damage may be associated with statin use, albeit rarely. The paper does not do more than raise the signal for further work and analysis of what must be regarded as a potentially very serious and perhaps avoidable or reversible adverse reaction, though it also suggests action to be taken if an ALS-like syndrome should occur in a patient using statins. METHODS: The 43 reports accounting for the disproportional reports in Vigibase (the database of the WHO Programme for International Drug Monitoring) are summarised and analysed for the diagnosis of an ALS-like syndrome. The issues of data quality and potential reporting bias are considered. RESULTS: 'Upper motor neurone lesion' is a rare adverse event reported in relationship to drugs in Vigibase (a database containing nearly 4 million ICSRs). Of the total of 172 ICSRs on this reported term, 43 were related to statins, of which 40 were considered further: all but one case was reported as ALS. In 34/40 reports a statin was the sole reported suspected drug. The diagnostic criteria were variable, and seven of the statin cases also had features of peripheral neuropathy. Of a total of 5534 ICSRs of peripheral neuropathy related to any drug in Vigibase, 547 were on statins. The disproportional reporting of statins and upper motor neurone lesion persisted after age stratification, and such disproportionality was not seen for statins and Parkinson's disease, Alzheimer's disease, extrapyramidal disorders, or multiple sclerosis-like syndromes. DISCUSSION: Because the cases were sometimes atypical we propose the use of the term 'ALS-like syndrome' and speculate whether this is part of a spectrum of rare neuromuscular damage. The diagnosis of ALS is often problematic, and the insidiousness and chronicity of the disease make causality with a drug difficult to assess. The disproportionally high reporting makes this an important signal nevertheless, since ALS is serious clinically and statins are so widely used. Wide use of the statins also makes a chance finding more probable, but is unlikely to cause disproportional reporting when there are no obvious biases identified. CONCLUSION: We emphasise the rarity of this possible association, and also the need for further study to establish whether a causal relationship exists. We do advocate that trial discontinuation of a statin should be considered in patients with serious neuromuscular disease such as the ALS-like syndrome, given the poor prognosis and a possibility that progression of the disease may be halted or even reversed.  相似文献   
70.
A novel noninvasive method of measuring local myocardial oxygen tension (pO2) In the perfused rat heart using 19F MRI is demonstrated. Tissue pO2 was determined on the basis of the 19F spin-lattice relaxation rate (R1) of perflubron (perfluorooctyl bromide) sequestered in the heart after IV infusion of an emulsion. Spectroscopic measurement of R1 was previously used to measure a global weighted average of oxygen status. 19F MRI now provides 3D spatial resolution indicating local cardiac pO2 under normally perfused, globally ischemic, and regionally ischemic conditions.  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