全文获取类型
收费全文 | 2374717篇 |
免费 | 195336篇 |
国内免费 | 4211篇 |
专业分类
耳鼻咽喉 | 34268篇 |
儿科学 | 72751篇 |
妇产科学 | 62932篇 |
基础医学 | 334921篇 |
口腔科学 | 67525篇 |
临床医学 | 215550篇 |
内科学 | 468737篇 |
皮肤病学 | 47931篇 |
神经病学 | 200785篇 |
特种医学 | 95956篇 |
外国民族医学 | 886篇 |
外科学 | 360412篇 |
综合类 | 56232篇 |
现状与发展 | 1篇 |
一般理论 | 977篇 |
预防医学 | 190629篇 |
眼科学 | 55471篇 |
药学 | 177538篇 |
4篇 | |
中国医学 | 4369篇 |
肿瘤学 | 126389篇 |
出版年
2018年 | 24212篇 |
2016年 | 20580篇 |
2015年 | 23283篇 |
2014年 | 33534篇 |
2013年 | 50832篇 |
2012年 | 68738篇 |
2011年 | 72281篇 |
2010年 | 42470篇 |
2009年 | 40863篇 |
2008年 | 68769篇 |
2007年 | 73105篇 |
2006年 | 74006篇 |
2005年 | 72042篇 |
2004年 | 69338篇 |
2003年 | 67018篇 |
2002年 | 66265篇 |
2001年 | 112450篇 |
2000年 | 116525篇 |
1999年 | 98333篇 |
1998年 | 27857篇 |
1997年 | 25522篇 |
1996年 | 25448篇 |
1995年 | 24609篇 |
1994年 | 23159篇 |
1993年 | 21554篇 |
1992年 | 79386篇 |
1991年 | 76398篇 |
1990年 | 73577篇 |
1989年 | 70842篇 |
1988年 | 65849篇 |
1987年 | 64804篇 |
1986年 | 61336篇 |
1985年 | 58401篇 |
1984年 | 44226篇 |
1983年 | 37659篇 |
1982年 | 22888篇 |
1981年 | 20336篇 |
1980年 | 19036篇 |
1979年 | 41301篇 |
1978年 | 28989篇 |
1977年 | 24346篇 |
1976年 | 22834篇 |
1975年 | 23966篇 |
1974年 | 29642篇 |
1973年 | 28045篇 |
1972年 | 26229篇 |
1971年 | 24152篇 |
1970年 | 22753篇 |
1969年 | 21089篇 |
1968年 | 19135篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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
992.
Early defibrillation along with well performed basic life support (BLS) after cardiac arrest, due to ventricular fibrillation is the gold standard for increasing patients survival. Within Germany there are two standardized schemes for the training of first responders as well as of paramedics, emergency medical technicians etc.; however, the use of public access defibrillation (PAD) is highly variable between localities. Results from the USA as well as from Germany indicate approaches to life-saving issues which need addressing. The paper by Caffrey reveals high regional efficiency for PAD along with BLS, while two German studies show the value of lay individuals in BLS. Zipes (USA) study shows that death due to cardiac arrest occurs at the patient’s home in more than 70%. Two recent, standardized US trials cast doubt on the efficacy of broadly deployed BLS-training programs for lay persons, preferring PAD and BLS training carried out strictly in accordance with the risk-ratio, for instance, of the people near to the first responders. Taking this into account, social insurance for occupational accidents offer qualified first responder training for more than 43 million employees (about half of the Germany population) in more than 3 million companies. It is necessary to find a synthesis between socio-economic demands on the one hand and ethical principles on the other for the emergency medicine network. 相似文献
993.
994.
995.
R Tootla G Kotru M A Connolly M S Duggal K J Toumba 《European journal of paediatric dentistry》2005,6(3):139-143
AIM: The purpose of this pilot study was to identify the subsurface enamel demineralising potential of two possible acidogenic lactose-based powders and their corresponding generic pump inhalers. METHODS: Ten healthy non-asthmatic adults participated in a 5- leg randomised crossover study including a 10% sucrose control. A twice-daily 400 microg dose of inhaler was applied in vitro to a demineralised enamel slab on the buccal flange of a mandibular removable appliance before in situ placement for 14 days each. Lesion parameters were determined using transverse microradiography and digitised image analysis. RESULTS: Minimal demineralisation occurred with sucrose, both pump and one powder inhaler. The remaining powder was associated with remineralisation (p = 0.29). Overall, mean lesion depth increased (p = 0.12). CONCLUSION: Asthma inhalers failed to demonstrate a significant acidogenic/cariogenic effect. 相似文献
996.
997.
998.
999.
An unusual, elongated, refractile cell morphology was observed in keratinocytes cultured from three patients with non-lethalis forms of junctional epidermolysis bullosa (JEB). To determine whether these changes might be related to altered cell adhesion, keratinocyte strains established from one patient were examined for adhesive, structural, and functional characteristics. JEB keratinocytes expressed keratin tonofilaments, as determined by staining with AE1 monoclonal antibodies and direct observation of tonofilaments by electron microscopy. JEB keratinocytes showed diminished cell-substratum adhesions, judged by interference reflection microscopy. Areas of diminished cell-substratum adhesion corresponded to F-actin-rich cell adhesions (focal adhesions) and not to cellular areas that abundantly express hemidesmosomal antigens. Analysis of cell-substratum adhesion by electron microscopy revealed extensive areas of cell-substratum separation in JEB keratinocytes that were not present in normal keratinocytes maintained in serum-free medium. Normal keratinocytes displayed numerous regions of focal contact between the ventral plasma membrane and the culture substratum, but these structures were not seen in JEB keratinocytes. Bundled actin filaments (stress fibers) were greatly diminished in expected regions of cell-substratum adhesion in JEB keratinocytes and, instead, displayed disorganized individual filaments. The growth rate of JEB keratinocytes was quite slow in culture, with a population doubling time of 2.7 d versus 1.5 d for normal keratinocytes under identical conditions. JEB keratinocytes also displayed a reduced ability to aggregate into colonies upon exposure to medium with increased extracellular calcium. JEB keratinocytes thus display adhesive, structural, and functional abnormalities that suggest this cell type may be central to the pathogenesis of junctional epidermolysis bullosa. Study of affected keratinocytes could be important to characterize associated molecular pathologies. 相似文献
1000.