全文获取类型
收费全文 | 387542篇 |
免费 | 26255篇 |
国内免费 | 8423篇 |
专业分类
耳鼻咽喉 | 4307篇 |
儿科学 | 11799篇 |
妇产科学 | 7318篇 |
基础医学 | 32326篇 |
口腔科学 | 8875篇 |
临床医学 | 43875篇 |
内科学 | 49962篇 |
皮肤病学 | 5220篇 |
神经病学 | 20210篇 |
特种医学 | 8636篇 |
外国民族医学 | 32篇 |
外科学 | 41856篇 |
综合类 | 57265篇 |
现状与发展 | 19篇 |
一般理论 | 29篇 |
预防医学 | 44458篇 |
眼科学 | 5574篇 |
药学 | 33946篇 |
430篇 | |
中国医学 | 31509篇 |
肿瘤学 | 14574篇 |
出版年
2023年 | 6334篇 |
2022年 | 11372篇 |
2021年 | 15494篇 |
2020年 | 14620篇 |
2019年 | 20052篇 |
2018年 | 17551篇 |
2017年 | 14442篇 |
2016年 | 12105篇 |
2015年 | 11586篇 |
2014年 | 22870篇 |
2013年 | 24931篇 |
2012年 | 21291篇 |
2011年 | 22872篇 |
2010年 | 18083篇 |
2009年 | 16593篇 |
2008年 | 16142篇 |
2007年 | 16636篇 |
2006年 | 14718篇 |
2005年 | 12793篇 |
2004年 | 10439篇 |
2003年 | 9140篇 |
2002年 | 7081篇 |
2001年 | 6388篇 |
2000年 | 5278篇 |
1999年 | 4638篇 |
1998年 | 3759篇 |
1997年 | 3574篇 |
1996年 | 3097篇 |
1995年 | 2979篇 |
1994年 | 2858篇 |
1993年 | 2288篇 |
1992年 | 2281篇 |
1991年 | 2004篇 |
1990年 | 1729篇 |
1989年 | 1568篇 |
1988年 | 1457篇 |
1987年 | 1247篇 |
1985年 | 3921篇 |
1984年 | 4876篇 |
1983年 | 3407篇 |
1982年 | 3871篇 |
1981年 | 3601篇 |
1980年 | 3193篇 |
1979年 | 2950篇 |
1978年 | 2559篇 |
1977年 | 1931篇 |
1976年 | 2183篇 |
1975年 | 1646篇 |
1974年 | 1435篇 |
1973年 | 1287篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
While much time has been spent deliberating about the definition of play, little emphasis has been placed on what children themselves perceive as play. The aim of the present study was to examine social context as a cue for children's perceptions of play and learning. Ninety-two children aged between four and six years (mean four years nine months) participated in the study and completed the Activity Apperception Story Procedure. Children were asked to sort photographic stimuli into those they believed depicted play/not play and learning/not learning. Each of the stimuli were identified by independent raters as containing one of the following social cues; teacher absence (solitary activity, parallel activity or cooperative activity) or teacher presence (teacher involved activity or teacher directed activity). Findings revealed that children associated teacher absence with play. More specifically, children made links between play and the presence of peers (parallel and cooperative activity). Findings are discussed in relation to play in the early years curriculum, differences in children's early educational experiences and the importance of understanding children's perceptions of play. 相似文献
32.
T. Pinzer M. Reiß H. Bourquain K. G. Krishnan G. Schackert 《Acta neurochirurgica》2006,148(10):1085-1090
Summary Aspergillosis belongs to the group of mycotic diseases of paranasal sinuses. The invasive forms, and particularly the fulminant
forms, are potentially fatal. Isolated aspergillosis of the sphenoid sinus or the clivus is a difficult diagnosis, since the
often misleading clinical manifestations of this rare disease develop late. These patients become apparent by neurological
signs such as cavernous sinus syndrome, pseudotumor of the pituitary or the orbit. Diagnosis is often made intra-operatively
or on histological examination.
We report a case of invasive aspergillosis uniquely involving the sellar area revealed by clinical features suggesting a pseudotumor
of the pituitary. Although such lesions are almost always seen in immune suppressed subjects, in our case, the patient was
immune competent and had no past history of sinusitis.
The question of whether, and when to perform limited or extensive surgery remains an issue for discussion, owing to the rarity
of this disease honed by lack of experience. It depends on several factors: the kind of disease, the immunity, the subtype
of invasive fungal sinusitis and the degree of tissue invasion. 相似文献
33.
X Dong M He X Song B Lu Y Yang S Zhang N Zhao L Zhou Y Li X Zhu R Hu 《Diabetic medicine》2007,24(12):1482-1486
AIMS: Our aim was to assess performances of the Cockcroft-Gault and simplified Modification of Diet in Renal Disease (MDRD) formulae in estimating glomerular filtration rate (GFR) in Chinese diabetic populations and their association with vascular risks. METHODS: A total of 1009 patients with Type 2 diabetes were categorized into low estimated GFR groups (GFR < 60 ml/min/1.73 m(2)) and control groups by the two equations. The performances of these formulae were assessed at different stages of kidney function. Carotid artery intima-media thickness (IMT) and the prevalence of diabetic retinopathy or albuminuria were compared among the groups. The ability of these formulae to identify established vascular risk markers using sensitivity, specificity, positive and negative predictive values were also compared. RESULTS: The prevalence of low estimated GFR was 32.7% with the Cockcroft-Gault formula and 5.2% with the MDRD formula, respectively. In low estimated GFR subjects by the MDRD formula, IMT was significantly thicker than those by the Cockcroft-Gault formula (1.2 mm vs. 1.0 mm; P < 0.05), with a higher prevalence of albuminuria (78.4 vs. 52.8%, P < 0.05) and diabetic retinopathy (46.5 vs. 30.5%; P < 0.05). The Cockcroft-Gault formula gave a specificity of 71.7% and a sensitivity of 37.0%, and the MDRD formula gave a specificity of 96.6% and a sensitivity of 7.9% in estimating low GFR relevant for established vascular risks. CONCLUSIONS: These formulae performed differently in Chinese diabetic populations. The simplified MDRD formula is minimally superior to the Cockcroft-Gault formula for its high specificity and positive predictive values in estimating low GFR relevant for vascular risks. 相似文献
34.
35.
36.
AIM: To undertake a systematic review of the diagnostic performance of clinical examination, sample acquisition and sample analysis in infected foot ulcers in diabetes. METHODS: Nineteen electronic databases plus other sources were searched. To be included, studies had to fulfil the following criteria: (i) compare a method of clinical assessment, sample collection or sample analysis with a reference standard; (ii) recruit diabetic individuals with foot ulcers; (ii) present 2 x 2 diagnostic data. Studies were critically appraised using a 12-item checklist. RESULTS: Three eligible studies were identified, one each on clinical examination, sample collection and sample analysis. For all three, study groups were heterogeneous with respect to wound type and a small proportion of participants had foot ulcers due to diabetes. No studies identified an optimum reference standard. Other methodological problems included non-blind interpretation of tests and the time lag between index and reference tests. Individual signs or symptoms of infection did not prove to be useful tests when assessed against punch biopsy as the reference standard. The wound swab did not perform well when assessed against tissue biopsy. Semiquantitative analysis of wound swab might be a useful alternative to quantitative analysis. The limitations of these findings and their impact on recommendations from relevant clinical guidelines are discussed. CONCLUSION: Given the importance of this topic, it is surprising that only three eligible studies were identified. It was not possible to describe the optimal methods of diagnosing infection in diabetic patients with foot ulceration from the evidence identified in this systematic review. 相似文献
37.
眼底动脉硬化与血压、血糖、血脂的多元分析与评估 总被引:1,自引:0,他引:1
目的探讨眼底动脉硬化与血压、血脂、血糖的相关性,评估中风危险度。方法对2004年5月至2008年10月就诊的患者335例,作为观察组,并与无症状的健康体检者180例作对照,动态检测眼底动脉硬化、血压、血糖、血脂的异常变化,并做综合量化评估。结果脑血管疾病与眼底动脉硬化、血压、血糖、血脂等因素密切相关。结论眼底动脉硬化、血糖、血脂、血压异常的量化评分,能够预估中风,以便采取预防性治疗。 相似文献
38.
目的探讨左半结肠癌急性梗阻Ⅰ期切除吻合的Ⅰ临床应用价值。方法对1988年1月至2006年12月24侧实施左半结肠癌急性梗阻Ⅰ期切除吻合手术患者的资料进行回顾性总结。结果24例均未发生吻合口漏,仅3例发生切口感染,经局部换药处理Ⅱ期愈合。结论积极的术前准备、术中彻底的肠减压能为左半结肠癌急性梗阻Ⅰ期切除吻合提供安全保证. 相似文献
39.
Teng-Yi Huang Hsiao-Wen Chung Fu-Nien Wang Cheng-Wen Ko Cheng-Yu Chen 《Magnetic resonance in medicine》2004,51(2):243-247
In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished. 相似文献
40.
中风毒邪论是一种与传统中医中风病理有所不同的理论 ,在中风毒邪论指导下形成解毒通络方是较为理想的神经保护剂 ,可解决目前神经保护治疗的主要障碍 ,有望成为提高中医治疗中风急性期疗效的关键 相似文献