全文获取类型
收费全文 | 1067篇 |
免费 | 28篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 6篇 |
妇产科学 | 17篇 |
基础医学 | 120篇 |
口腔科学 | 10篇 |
临床医学 | 60篇 |
内科学 | 162篇 |
皮肤病学 | 10篇 |
神经病学 | 92篇 |
特种医学 | 21篇 |
外科学 | 67篇 |
综合类 | 87篇 |
预防医学 | 58篇 |
眼科学 | 30篇 |
药学 | 274篇 |
中国医学 | 33篇 |
肿瘤学 | 69篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 23篇 |
2020年 | 18篇 |
2019年 | 51篇 |
2018年 | 59篇 |
2017年 | 30篇 |
2016年 | 19篇 |
2015年 | 18篇 |
2014年 | 63篇 |
2013年 | 43篇 |
2012年 | 60篇 |
2011年 | 81篇 |
2010年 | 59篇 |
2009年 | 57篇 |
2008年 | 55篇 |
2007年 | 51篇 |
2006年 | 41篇 |
2005年 | 28篇 |
2004年 | 27篇 |
2003年 | 23篇 |
2002年 | 21篇 |
2001年 | 20篇 |
2000年 | 20篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 12篇 |
1984年 | 23篇 |
1983年 | 22篇 |
1982年 | 19篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 2篇 |
1973年 | 6篇 |
排序方式: 共有1117条查询结果,搜索用时 156 毫秒
101.
102.
Elastase and antielastase activities were measured in bronchoalveolar lavage fluid (BALF) and their relationship to bronchoalveolar lavage (BAL) neutrophil numbers was assessed in order to determine whether the elevated BAL neutrophil count can predict a shift in the elastase/antielastase balance. BAL samples were obtained from 133 randomly selected patients undergoing diagnostic bronchoscopy with BAL. Elastase and antielastase activities were determined using the synthetic substrate MeO-Suc-Ala-Ala-Pro-Val-pNA. In a random subset of 24 samples, the antioxidant capacity was measured as the inhibition of peroxyl radical-mediated oxidation of B-phycoerythrin. Only 7 of the BAL samples exhibited measurable elastase activity and all but one of these had a BAL neutrophil count greater than 100 × 103/ml. Antielastase activity was measurable in 124 samples exhibiting no free elastase activity. There was a tendency for lower antielastase activity to be associated with higher neutrophil numbers, but this did not translate into a statistically significant correlation over all samples. There was no significant correlation between antioxidant capacity and either the neutrophil number or antielastase activity. It is concluded that BAL neutrophil numbers do not, in general, predict the status of elastase/antielastase balance in the epithelial lining fluid and that the antioxidant mechanisms in the epithelial lining fluid do not appear to be related to the antielastase capacity. 相似文献
103.
Marieke H. Heineke Aranka V. Ballering Agnès Jamin Sanae Ben Mkaddem Renato C. Monteiro Marjolein Van Egmond 《Autoimmunity reviews》2017,16(12):1246-1253
Immunoglobulin A vasculitis (IgAV), also referred to as Henoch-Schönlein purpura, is the most common form of childhood vasculitis. The pathogenesis of IgAV is still largely unknown. The disease is characterized by IgA1-immune deposits, complement factors and neutrophil infiltration, which is accompanied with vascular inflammation. Incidence of IgAV is twice as high during fall and winter, suggesting an environmental trigger associated to climate. Symptoms can resolve without intervention, but some patients develop glomerulonephritis with features similar to IgA nephropathy that include hematuria, proteinuria and IgA deposition in the glomerulus. Ultimately, this can lead to end-stage renal disease. In IgA nephropathy immune complexes containing galactose-deficient (Gd-)IgA1 are found and thought to play a role in pathogenesis. Although Gd-IgA1 complexes are also present in patients with IgAV with nephritis, their role in IgAV is disputed. Alternatively, it has been proposed that in IgAV IgA1 antibodies are generated against endothelial cells. We anticipate that such IgA complexes can activate neutrophils via the IgA Fc receptor FcαRI (CD89), thereby inducing neutrophil migration and activation, which ultimately causes tissue damage in IgAV. In this Review, we discuss the putative role of IgA, IgA receptors, neutrophils and other factors such as infections, genetics and the complement system in the pathogenesis of IgA vasculitis. 相似文献
104.
Smallpox vaccination is the only currently effective mean to combat the threat of variola virus used as a bioterrorism agent, although it is responsible for a rare but serious complication, the postvaccinal encephalitis (PVE). Development of safer vaccines therefore is a high priority as the PVE physiopathology is not well understood to date. If vaccinia virus (VACV) is responsible for PVE by central nervous system (CNS) dissemination, trans-migration of the VACV across the blood-brain barrier (BBB) would be supposed to be essential. Given the complexity of the pathogenesis of vaccinia neurovirulence, an in vitro BBB model was used to explore the mechanism of VACV to induce BBB permeability. Two VACV strains were studied, the neurovirulent Western Reserve strain (VACV-WR) and the vaccine reference Lister strain (VACV-List). A mouse model was also developed to study the ability of these two viral strains to propagate in the brain from the blood compartment, their neurovirulence and their neuropathogenesis. In vitro, the loss of permeability resulted from the tight-junctions disruption was induced by virus replication. The ability of VACV to release infectious particles at the abluminal side suggests the capacity of both VACV strains to migrate across the BBB from the blood to the CNS. In vivo, the virus replication in mice CNS was strain-dependent. The VACV-WR laboratory strain proved to be neuroinvasive and neurovirulent, whereas the VACV-List strain is safe in physiological conditions. Mice PVE was observed only with VACV-WR in the co-infection model, when BBB opening was obtained by lipopolysaccharide (LPS) treatment. This study suggests that VACV is able to cross the BBB but encephalitis occurs only in the presence of a co-infection by bacteria. So, a model of co-infection, mimicked by LPS treatment, could have important implication towards the assessment of neurovirulence of new vaccines. 相似文献
105.
Background
Dry age-related macular degeneration (AMD) is a leading cause of untreatable, progressive central vision loss, social isolation, and disability in older people. Evidence suggests that diet (eg, the Mediterranean dietary pattern or increased oral carotenoid intake) might protect against dry AMD progression. The aim of this pilot study was to test the feasibility of a participant-informed community kitchens intervention (Eating for Eye Health project) to implement dietary behaviour change, to benefit macular health of older adults.Methods
Adults (≥50 years) with documented visual impairment due to dry AMD were invited, with a partner, carer, or friend for support, via a National Institute of Health Research mailing list, to participate in a focus group and pilot intervention in London, UK. The intervention was an ice-breaker session and a cookery activity with integrated health promotion information; it was participant codesigned to increase capability and opportunity for implementing dietary change for macular health. For the cookery activity, participants were divided into small groups, with different groups preparing different courses of a three-course meal containing carotenoid-rich foods, which they ate together. The primary outcome was participants' self-reported capability in cooking skills for eye health, evaluated before and after the intervention, using a ten-point confidence score (10=most confident). Secondary outcomes were participant-rated taste acceptability of the food, evaluated by a two-point (a physical thumbs-up or thumbs-down motion) scale for each course, and subjective experience of the intervention (thematic analysis of written qualitative feedback consisting of unstructured feedback using post-it notes immediately after the event and a standardised email questionnaire 1 week later).Findings
12 adults (ten with dry AMD and two partners or friends) participated. All participants reported increased confidence scores, with improvement in scores ranging from 2 to 6 points, with all giving a score of 7 points or higher after the intervention, and rated food as acceptable in taste. Thematic analysis of qualitative written feedback, immediately and 1 week after the intervention, identified positive subjective experiences of “social participation” and “peer support”.Interpretation
This pilot study provides evidence to support the feasibility of National Health Service social prescribing of community cookery programmes for older people with dry AMD to increase their capability and social opportunity to implement dietary behaviour change for eye health.Funding
University College London Beacon Bursary (for RG to support Eating for Eye Health public engagement work). 相似文献106.
Guatimosim S Dilly K Santana LF Saleet Jafri M Sobie EA Lederer WJ 《Journal of molecular and cellular cardiology》2002,34(8):941-950
The elementary event of Ca(2+) release in heart is the Ca(2+) spark. It occurs at a low rate during diastole, activated only by the low cytosolic [Ca(2+)](i). Synchronized activation of many sparks is due to the high local [Ca(2+)](i) in the region surrounding the sarcoplasmic reticulum (SR) Ca(2+) release channels and is responsible for the systolic [Ca(2+)](i) transient. The biophysical basis of this calcium signaling is discussed. Attention is placed on the local organization of the ryanodine receptors (SR Ca(2+) release channels, RyRs) and the other proteins that underlie and modulate excitation-contraction (EC) coupling. A brief review of specific elements that regulate SR Ca(2+) release (including SR lumenal Ca(2+) and coupled gating of RyRs) is presented. Finally integrative calcium signaling in heart is presented in the context of normal heart function and heart failure. 相似文献
107.
目的 探讨乙酰肝素酶 (HPA)反义寡核苷酸 (ASODN)对人食管癌 EC970 6细胞中 HPA蛋白表达的影响。方法 将食管癌 EC970 6细胞体外分组贴壁培养 ,实验组分别用设计合成的 10、2 0、30 μm ol/ L 三种浓度的 4条封闭肝素酶不同基因位点的 ASODN(ASODN- t1 、ASODN- t2 、ASODN- t3、ASODN- t4 )。对照 组为 1条无关寡核苷酸 (N - ODN)转染 EC970 6细胞 ,对照 组为无转染。采用免疫组化 (SP)法检测各组 EC970 6细胞中HPA蛋白表达情况。结果 实验组中 3种浓度的 4条 HPA- t2 效应最强。不同浓度的 4条 HPA ASODN对EC970 6细胞中 HPA蛋白表达的影响无统计学意义 (P >0 .0 5 ) ,但均低于对照 组及对照 组 (无转染 )(P<0 .0 5 )。结论 HPA ASODN可抑制食管癌 EC970 6细胞中 HPA蛋白表达。 相似文献
108.
同型半胱氨酸对血管内皮细胞合成蛋白聚糖的影响 总被引:1,自引:0,他引:1
为探讨同型半胱氨酸对血管内皮细胞合成蛋白聚糖的影响,采用400umol/L同型半胱氨酸作用于培养的人脐静脉内皮细胞,以^35S-Na2SO4为示踪物标记细胞合成的蛋白聚糖,通过离子交换层析,凝胶过滤层析分离蛋白聚糖。结果发现,实验组培养液中总蛋白聚糖降低,硫酸乙酰肝素蛋白聚糖及硫酸软骨素-硫酸皮肤素蛋白聚糖含量也降低,但其百分含量未见改变。细胞层中蛋白聚糖未见明显变化。 相似文献
109.
Rex M. Philpot Lynn Wecker Cheryl L. Kirstein 《International journal of developmental neuroscience》2009
Individuals who begin using alcohol prior to 14 years of age are 4 times more likely to progress to addiction than those who do not initiate use until 21 years of age. The nucleus accumbens septi undergoes dramatic developmental transitions during the adolescent period, and dopaminergic activity within this region has been identified as a central neurochemical mediator of drug reward, addiction and dependence. Thus, alcohol-induced neurochemical alterations in dopaminergic activity within this brain region likely mediate the heightened vulnerability to addiction observed in adolescent alcohol users. To investigate this idea, Sprague–Dawley rats were exposed to intraperitoneal injections of either saline or ethanol (0.5, 1.0 or 2.0 g/kg) twice daily over four days beginning on postnatal day 21, 31, 41 or 56. Cannulas were implanted toward the nucleus accumbens septi, subsequent in vivo microdialysis was used to collect samples, and both basal and ethanol-stimulated dopamine overflow was measured using high performance liquid chromatography with electrochemical detection. A developmental transition in basal levels of dopamine in the nucleus accumbens septi was apparent with peak levels at postnatal day 45. An ethanol challenge produced unique responses across ages, with greater peak effects relative to baseline in younger animals (postnatal day 25 and 35). Following repeated exposure to ethanol, a significant increase in basal dopamine was apparent for all ages, and when these animals were challenged with ethanol, peak effects relative to baseline were decreased in younger animals, but unchanged in older animals (postnatal day 45 and 60). Results indicate that there is a key developmental transition in the ability of rats to adapt to the effects of repeated ethanol exposure, which occurs between postnatal day 35 and 45. This alteration may explain the increased addiction vulnerability observed in individuals who initiate alcohol use during early adolescence. 相似文献
110.