全文获取类型
收费全文 | 3364694篇 |
免费 | 255267篇 |
国内免费 | 8839篇 |
专业分类
耳鼻咽喉 | 45626篇 |
儿科学 | 110149篇 |
妇产科学 | 91887篇 |
基础医学 | 474210篇 |
口腔科学 | 94324篇 |
临床医学 | 309062篇 |
内科学 | 661500篇 |
皮肤病学 | 77236篇 |
神经病学 | 277859篇 |
特种医学 | 131063篇 |
外国民族医学 | 952篇 |
外科学 | 504057篇 |
综合类 | 72861篇 |
现状与发展 | 5篇 |
一般理论 | 1291篇 |
预防医学 | 265838篇 |
眼科学 | 74838篇 |
药学 | 246893篇 |
11篇 | |
中国医学 | 6629篇 |
肿瘤学 | 182509篇 |
出版年
2019年 | 26163篇 |
2018年 | 36925篇 |
2017年 | 28330篇 |
2016年 | 32608篇 |
2015年 | 36767篇 |
2014年 | 50984篇 |
2013年 | 77020篇 |
2012年 | 101867篇 |
2011年 | 108042篇 |
2010年 | 65128篇 |
2009年 | 62328篇 |
2008年 | 100794篇 |
2007年 | 107331篇 |
2006年 | 109110篇 |
2005年 | 104940篇 |
2004年 | 101116篇 |
2003年 | 97512篇 |
2002年 | 93931篇 |
2001年 | 162033篇 |
2000年 | 166451篇 |
1999年 | 140034篇 |
1998年 | 40448篇 |
1997年 | 35968篇 |
1996年 | 36443篇 |
1995年 | 35406篇 |
1994年 | 32679篇 |
1993年 | 30564篇 |
1992年 | 110412篇 |
1991年 | 106608篇 |
1990年 | 103252篇 |
1989年 | 99390篇 |
1988年 | 91318篇 |
1987年 | 89727篇 |
1986年 | 84421篇 |
1985年 | 80671篇 |
1984年 | 60447篇 |
1983年 | 51149篇 |
1982年 | 30425篇 |
1981年 | 27263篇 |
1979年 | 53928篇 |
1978年 | 38315篇 |
1977年 | 32341篇 |
1976年 | 30041篇 |
1975年 | 32050篇 |
1974年 | 38032篇 |
1973年 | 36275篇 |
1972年 | 33882篇 |
1971年 | 31446篇 |
1970年 | 28925篇 |
1969年 | 27527篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
911.
Contour defects resulting in deformity caused by lack of tissue can be improved by conventional surgery using autologous tissue, but there is always a donor site morbidity. Integra has been available since the early 1980's for use in acute burns and more recently in reconstruction. It has been shown histologically to act as a tissue regeneration template. The regenerated dermis is buried under an autologous thin split-skin graft. In this study, the principle of burying Integra (without the silicone layer) has been applied to deep tissue defects in 12 reconstructive cases. Such regenerated tissues survive at least 3 years after burying. Modification to the technique to avoid visible edges are being developed. 相似文献
912.
Christine E. Marx William T. Trost Lawrence J. Shampine Robert D. Stevens Christine M. Hulette David C. Steffens John F. Ervin Marian I. Butterfield Daniel G. Blazer Mark W. Massing Jeffrey A. Lieberman 《Neuropsychopharmacology》2006,60(12):1287-1294
BACKGROUND: Few data are currently available investigating neurosteroids (NS) in Alzheimer's disease (AD). The NS allopregnanolone may be decreased in serum and plasma in patients with AD, but it is unclear if allopregnanolone is also reduced in brain. Because a number of NS exhibit neuroprotective effects and impact cognitive performance in rodent models, these molecules may be relevant to the pathophysiology of neurodegenerative disorders. We therefore investigated prefrontal cortex (PFC) NS levels in AD. METHODS: Neurosteroid levels (allopregnanolone, pregnenolone, dehydroepiandrosterone [DHEA]) were determined in postmortem PFC in 14 male subjects with AD and 15 cognitively intact male control subjects by gas chromatography/mass spectrometry preceded by high-performance liquid chromatography purification. RESULTS: Subjects with AD exhibit significant reductions in allopregnanolone compared with cognitively intact control subjects (median levels = 2.50 ng/g vs. 5.59 ng/g, respectively; p = .02). Allopregnanolone levels are inversely correlated with neuropathological disease stage (Braak), r = -.49, p = .007. Median DHEA levels are elevated in subjects with AD (p = .01). CONCLUSIONS: Subjects with AD demonstrate significant reductions in PFC allopregnanolone levels, a finding that may be relevant to neuropathological disease stage severity. Neurosteroids may have utility as candidate biomarkers in AD. 相似文献
913.
Maher Saqqur MD Michael D. Hill MD MSc FRCPC Andrei V. Alexandrov MD Jayanta Roy MD Marcia Schebel BSc Andrea Krol BSc Zsolt Garami MD Ashfaq Shuaib MD FRCPC Andrew M. Demchuk MD FRCPC 《Journal of neuroimaging》2006,16(4):323-328
BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies. 相似文献
914.
Michele D. Mignogna Stefano Fedele Lucio Lo Russo Lorenzo Lo Muzio 《Journal of oral pathology & medicine》2003,32(4):200-205
BACKGROUND: The recurrent chronic orofacial swelling caused by orofacial granulomatosis (OFG) can cause significant cosmetic and functional problems but can be prevented if the disease is diagnosed early and promptly treated. Although the enlargement of the lips is described to be the most common presenting complaint, the clinical onset of OFG may be characterized by minor associated mucosal and neurological manifestations, making early diagnosis very difficult or, sometimes, merely presumable. PATIENTS AND METHODS: We retrospectively analyzed the clinical manifestations of 19 patients with OFG, who were examined at our institution between 1998 and 2002, in order to determine their initial manifestations and presenting symptoms. RESULTS: A total of 10 patients showed classical recurrent enlargement of the lips (six lower; four upper) as presenting symptom. In the other nine patients, OFG onset was characterized by transient unilateral facial nerve palsy (two cases), intraoral manifestations (two cases), recurrent swelling of the periorbital area (two cases), of the chin (one case), of the zygomatic area (one case), and of the cheeks (one case). CONCLUSION: Our data underlined that OFG onset could be frequently characterized by widely variable, multiform, and temporary clinical findings. Involvement of atypical sites of the orofacial region and presence of single minor manifestations may occur as presenting symptoms, often preceding the development of traditional clinical findings. 相似文献
915.
Summary The third-stage larvae of Daniconema anguillae Moravec et K?ie, 1987 are found in the eels fins caught from Dringis Lake (Lithuanian National park). The morphology of these
larvae is briefly described. 相似文献
916.
917.
918.
Rachel A. Woolrich Myra J. Cooper Hannah M. Turner 《Cognitive therapy and research》2006,30(6):735-748
Objective: The study explored the semantic content and origins of negative self-beliefs, and their functional links to “not eating enough” and other behaviors, in participants with anorexia nervosa (AN). Method: Fifteen women meeting DSM-IV criteria for AN were compared with 17 dieting and 18 non-dieting women matched on age and number of years of education. The main outcome measure was a semi-structured interview. Results: Six themes were identified in the beliefs of participants with AN. These were, in order of decreasing frequency, powerlessness (present in all but three AN participants), failure, defectiveness, unattractiveness, worthlessness and emptiness. Importantly, powerlessness and failure beliefs were consistently present independent of Beck Depression Inventory-II scores. The negative early life experiences associated with these beliefs had high distress and responsibility ratings. Participants with AN reported that they employed specific behaviors, particularly ‘not eating enough,’ and ‘placating others,’ to try to reduce the cognitive and emotional impact of their negative self-beliefs. Discussion: The findings are discussed in relation to the role of powerlessness and the function of “not eating enough” in cognitive theory and therapy for AN.
相似文献
相似文献
919.
Robert J Derksen Fred C Bakker Emil A Heilbron Pieter C Geervliet Irma M Spaans Elly S M de Lange-de Klerk Bart Veenings Peter Patka Henk J Th M Haarman 《European journal of emergency medicine》2006,13(1):3-8
OBJECTIVES: In the quest for a cost-effective and quality-preserving solution to manage crowding in the emergency department, the possibility of deploying regular emergency nurses for the treatment of acute ankle injuries was investigated. The aim of this study is to compare the diagnostic accuracy of emergency nurses with that of senior house officers in interpreting ankle and foot radiographs. METHODS: A prospective study comparing the assessment of 60 radiographs (30 feet and 30 ankles) by 16 emergency nurses before and after an educational session was performed. Each subset of 30 radiographs contained 12 fractures, hand-picked by a radiologist to represent everyday traumatology in the emergency department. The control group consisted of eight senior house officers representing everyday expertise. The outcome of the diagnostic assessment, represented as the pooled sensitivity and specificity for both groups, was compared using Z-statistics. RESULTS: Before the training session, the specialized emergency nurse group showed a sensitivity of 0.87 (confidence interval 0.83-0.91) compared with 0.93 (confidence interval 0.88-0.96) for the control group (P = 0.05). The specificity of specialized emergency nurses was 0.87 (confidence interval 0.81-0.92) compared with 0.93 (confidence interval 0.89-0.95) for the senior house officers (P < 0.05). After the training session, specialized emergency nurse diagnostic parameters did not differ significantly from the control group, displaying a sensitivity of 0.89 (confidence interval 0.86-0.92) and specificity of 0.92 (confidence interval 0.87-0.95). CONCLUSION: Before the training session, the specialized emergency nurse group showed a significantly lower accuracy than the SHO group. After training, however, the diagnostic accuracy did not differ significantly between groups. Therefore, we conclude that emergency nurses are able to accurately interpret foot and ankle radiographs after a short educational session. 相似文献
920.