全文获取类型
收费全文 | 283篇 |
免费 | 13篇 |
国内免费 | 19篇 |
专业分类
儿科学 | 11篇 |
妇产科学 | 2篇 |
基础医学 | 40篇 |
口腔科学 | 8篇 |
临床医学 | 26篇 |
内科学 | 35篇 |
皮肤病学 | 7篇 |
神经病学 | 6篇 |
特种医学 | 62篇 |
外科学 | 20篇 |
综合类 | 20篇 |
预防医学 | 22篇 |
药学 | 42篇 |
中国医学 | 1篇 |
肿瘤学 | 13篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 13篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 24篇 |
2006年 | 20篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 3篇 |
排序方式: 共有315条查询结果,搜索用时 15 毫秒
51.
Stimulation of tyrosine phosphorylation after ligation of beta7 and beta1 integrins on human B cells 总被引:2,自引:0,他引:2
Manie SN; Astier A; Wang D; Phifer JS; Chen J; Lazarovits AI; Morimoto C; Freedman AS 《Blood》1996,87(5):1855-1861
B lymphocytes express several members of the integrin family of adhesion molecules that mediate cell-cell and cell-extracellular matrix interactions. In addition to beta1 integrins, predominantly alpha4 beta1, mature B cells also express alpha4 beta7, which is a receptor for vascular cell adhesion molecule-1 and fibronectin, and is also involved in the homing of B cells to mucosal sites through binding to a third ligand, mucosal address in cell adhesion molecule-1. Here we describe that crosslinking of alpha4 beta7 integrins on B cell lines and normal tonsillar B cells, induces tyrosine phosphorylation of multiple substrates of 105-130 kD, indicating that beta7 integrin plays a role as signaling molecule in B cells. This pattern of phosphorylated proteins was very similar to that induced following ligation of alpha4 beta1. Interestingly, ligation of alpha5 beta1 or alpha6 beta1 also stimulated the 105-125 kD group of phosphorylated proteins, whereas ligation of beta2 integrins did not. The focal adhesion tyrosine kinase p125FAK was identified as one of these substrates. Beta1 or beta7 mediated tyrosine phosphorylations were markedly decreased when the microfilament assembly was inhibited by cytochalasin B. These results suggest that intracellular signals initiated by different integrins in B cells may converge, to similar cytoskeleton-dependent tyrosine phosphorylated proteins. 相似文献
52.
High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy 总被引:2,自引:1,他引:2
Brown RA; Herzig RH; Wolff SN; Frei-Lahr D; Pineiro L; Bolwell BJ; Lowder JN; Harden EA; Hande KR; Herzig GP 《Blood》1990,76(3):473-479
Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens. 相似文献
53.
Pedro Magalh?es Edgar JR Sanhangala Isildro M Dombele Henrique SN Ulundo Daniel P Capingana Amílcar BT Silva 《Cardiovascular journal of Africa》2015,26(2):57-62
High salt (sodium chloride) consumption is an important determinant of high blood pressure and cardiovascular risk. According to World Health Organisation (WHO) statistics, over 80% of cardiovascular disease (CVD) deaths take place in low-and middle-income countries, and elevated blood pressure levels were a major cause of these CVD deaths in those countries.1 Lifestyle factors such as unhealthy diet, physical inactivity, tobacco use and harmful use of alcohol have been considered the most important behavioural risk factors for heart disease and stroke.2Among dietary factors, high salt intake has been the most strongly associated with raised blood pressure and increased risk of stroke and CVD.3 Therefore dietary sodium restriction has been recommended as a non-pharmacological approach to blood pressure lowering,4-6 and for the prevention and control of non-communicable diseases at the population level.7,8Cumulative evidence has shown that even a modest reduction in salt intake was associated with blood pressure lowering and therefore with a significant reduction in incidence of cardiovascular events.9-12 Furthermore, data from the most recent systematic review and meta-analyses has shown the benefit of lowering sodium intake in apparently healthy adults and children,13 and in both hypertensive and normotensive individuals, irrespective of gender and ethnic group.9Since hypertension is associated with CVD worldwide, a public health intervention to reduce high blood pressure must target the role of lifestyle, particularly reduced sodium intake.7 Therefore, several countries have initiated strategies to reduce dietary salt intake in the general population by a combination of various procedures such as public education, food labelling, and collaboration with the food industry to reduce the salt content of processed food.14Among sub-Saharan African countries, only Nigeria and South Africa have developed dietary guidelines regarding salt intake.15 Recently, the South African government implemented important specific legislation towards decreasing salt intake in the population by reducing sodium content of processed foods by industries.16 Therefore, the current public health recommendation is that countries should launch national initiatives to reduce the over-consumption of salt as part of non-communicable disease prevention and healthy nutrition policies for limiting salt intake to less than 5 g/day for the general population including children.7 Despite of this guideline, however, high sodium intake remains prevalent around the world, with average daily salt intake varying from 5 to 18 g/day per person.17Although processed foods have been found to be the principal source of excessive dietary salt intake,18 sources of dietary sodium vary largely worldwide and may be influenced by cultural context and dietary habits of the population.19 In sub-Saharan African countries experiencing demographic and epidemiological transition, the rapid rise in prevalence of CVD (chiefly hypertension) has been attributed to lifestyle change, including high dietary sodium intake.20,21 However, consistent data from studies on risk factors are lacking for the majority of these countries.With regard to Angola, available data from a cross-sectional study reported a high prevalence of multiple cardiovascular risk factors, such as hypertension, sedentary lifestyle, electrocardiographic left ventricular hypertrophy,22 and high rate of the metabolic syndrome23 in an apparently healthy middle-aged population of university public employees living in urban and peri-urban areas.Determining the level of sodium intake in the population is crucial to establish intervention strategies and policy on reduction of sodium intake. For medical students in particular, it is very important to assess their awareness regarding dietary salt intake, since they are the future providers of healthcare information for the counselling of people about the need to reduce salt consumption. The aim of this study was to determine salt intake and to assess the knowledge, attitude and behaviour regarding dietary salt among medical students. 相似文献
54.
Wai Hoe Ng MBBS Ning Chou MBCHB FRCS Timothy Lee MBBS FRCS SN 《Journal of clinical neuroscience》2001,8(6):580-583
The authors describe a case of a 59 year-old Chinese lady with a history of spontaneous left caroticocavernous fistula in 1988 treated by left internal carotid artery clipping and muscle embolisation. She subsequently presented with a subarachnoid haemorrhage in November 1997 secondary to rupture of an unclippable giant right internal carotid artery aneurysm. This was treated satisfactorily with bilateral cervical carotid artery to proximal middle cerebral artery bypass followed by balloon occlusion. Postoperatively, the patient has no neurological deficit and CT angiogram shows good patency of both grafts 6 months after surgery. 相似文献
55.
P van Ruitenbeek A Sambeth A Vermeeren SN Young WJ Riedel 《British journal of pharmacology》2009,157(1):92-103
Background and purpose:
Animal studies show that histamine plays a role in cognitive functioning and that histamine H3-receptor antagonists, which increase histaminergic function through presynaptic receptors, improve cognitive performance in models of clinical cognitive deficits. In order to test such new drugs in humans, a model for cognitive impairments induced by low histaminergic functions would be useful. Studies with histamine H1-receptor antagonists have shown limitations as a model. Here we evaluated whether depletion of L-histidine, the precursor of histamine, was effective in altering measures associated with histamine in humans and the behavioural and electrophysiological (event-related-potentials) effects.Experimental approach:
Seventeen healthy volunteers completed a three-way, double-blind, crossover study with L-histidine depletion, L-tyrosine/L-phenylalanine depletion (active control) and placebo as treatments. Interactions with task manipulations in a choice reaction time task were studied. Task demands were increased using visual stimulus degradation and increased response complexity. In addition, subjective and objective measures of sedation and critical tracking task performance were assessed.Key results:
Measures of sedation and critical tracking task performance were not affected by treatment. L-histidine depletion was effective and enlarged the effect of response complexity as measured with the response-locked lateralized readiness potential onset latency.Conclusions and implications:
L-histidine depletion affected response- but not stimulus-related processes, in contrast to the effects of H1-receptor antagonists which were previously found to affect primarily stimulus-related processes. L-histidine depletion is promising as a model for histamine-based cognitive impairment. However, these effects need to be confirmed by further studies. 相似文献56.
Bronchial artery embolization in the management of hemoptysis: technical aspects and long-term results 总被引:26,自引:0,他引:26
Uflacker R; Kaemmerer A; Picon PD; Rizzon CF; Neves CM; Oliveira ES; Oliveira ME; Azevedo SN; Ossanai R 《Radiology》1985,157(3):637-644
Seventy-five patients with hemoptysis were treated with bronchial artery embolization (BAE). The procedure was performed with Hexabrix (sodium methylglucamine ioxaglate), Mikaelson catheters, and Gelfoam particles. Angiographic evaluation of the bronchial artery anatomy revealed ten different configurations, which are described. The embolization attempt failed in three cases (4%); eight additional patients (10.7%) were excluded from the series because of inadequate data. In the remaining 64 patients, 41 underwent BAE alone and 23 underwent either chemotherapy or surgery in addition to embolization. Immediate control of hemoptysis was achieved in 49 of 64 patients (76.6%). Long-term control of hemoptysis was achieved in 46 of the 56 patients included in the long-term follow-up (82.1%). Eight of the 64 patients were lost to follow-up, which ranged from one to 47 months (mean 24.8 months). Hemoptysis recurred in 12 of 56 patients (severe in 10, mild in 2) (21.4%). Twelve patients died (21.4%), five of them due to hemoptysis (8.9%). None of the patients who died of hemoptysis had responded to initial BAE. It is concluded that BAE is an effective treatment for immediate control of life-threatening hemoptysis, allowing long-term control of bleeding in the majority of patients. 相似文献
57.
报道了β-阻滞剂塞利洛尔的简便制备方法,即以对乙氧基苯胺为原料,经酰胺化,傅克反应,以环氧氯丙烷取代,最后用叔丁胺直接与环氧基反应开环等4步反应制得。比文献五步反应缩短了一步,产物经元素分析、红外光谱、核磁共振谱、质谱等分析确定结构。 相似文献
58.
正常人口服磷酸川芎嗪的药代动力学研究 总被引:26,自引:0,他引:26
本文建立了用高效液相色谱法测定人体内川芎嗪血药浓度的方法,以C18化学键合硅胶(10μgm)为固定相,以甲醇—水(58:42)为流动相,280 nm俭测,安眠酮为内标,进行定量测定,得出俭测限为3.5 ng(S/N=4),最低检测血清浓度为17.4 ng/ml,川芎嗪血药浓度在0.029~5.82μg/ml范围内,线性关系良好,方法回收率为99.84%。方法重现性好,专一性强,内源性物质、代谢产物及同时服用的药物均不干扰。用本法测定了健康人口服川芎嗪的药代动力学参数。 相似文献
59.
Extranodal malignant lymphoma: detection with FDG PET versus CT 总被引:19,自引:0,他引:19
Moog F; Bangerter M; Diederichs CG; Guhlmann A; Merkle E; Frickhofen N; Reske SN 《Radiology》1998,206(2):475
60.