首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   681篇
  免费   35篇
  国内免费   29篇
耳鼻咽喉   6篇
儿科学   17篇
妇产科学   7篇
基础医学   76篇
口腔科学   56篇
临床医学   50篇
内科学   205篇
皮肤病学   16篇
神经病学   80篇
特种医学   86篇
外科学   39篇
综合类   12篇
预防医学   55篇
眼科学   6篇
药学   15篇
中国医学   4篇
肿瘤学   15篇
  2023年   3篇
  2022年   12篇
  2021年   20篇
  2020年   11篇
  2019年   17篇
  2018年   19篇
  2017年   11篇
  2016年   19篇
  2015年   20篇
  2014年   34篇
  2013年   31篇
  2012年   42篇
  2011年   43篇
  2010年   28篇
  2009年   21篇
  2008年   24篇
  2007年   48篇
  2006年   30篇
  2005年   27篇
  2004年   15篇
  2003年   19篇
  2002年   13篇
  2001年   11篇
  2000年   14篇
  1999年   12篇
  1998年   15篇
  1997年   11篇
  1996年   9篇
  1995年   9篇
  1994年   17篇
  1993年   13篇
  1992年   7篇
  1991年   7篇
  1990年   9篇
  1989年   11篇
  1988年   12篇
  1987年   4篇
  1986年   8篇
  1985年   8篇
  1984年   11篇
  1983年   6篇
  1982年   4篇
  1981年   4篇
  1980年   8篇
  1978年   6篇
  1977年   9篇
  1976年   5篇
  1975年   3篇
  1965年   1篇
  1939年   1篇
排序方式: 共有745条查询结果,搜索用时 20 毫秒
41.
Summary There are few reports of pulmonary hypertension in Gaucher disease. We report a patient who showed significant clinical improvement after treatment with sildenafil.  相似文献   
42.
The population living along the riverbanks of the Amazon basin depends heavily on fish for nutritional support. Mono-methyl-mercury (MMHg) concentrates in fish, which can contaminate humans, the risk depending not only on fish MMHg concentration but also on the amount of fish consumed. We sampled nine locations of the Rio Negro basin, differing in water pH, Hg concentrations, and dissolved organic carbon (DOC), and determined total Hg from 951 fish samples of species representative of the food web: herbivorous, detritivorous, omnivorous, and piscivorous. Mercury concentrations varied widely in all species but showed a trend that depended on fish feeding strategies. The highest mean concentration was found in the piscivorous species (688.90 ng/g–1), followed by omnivorous (190.30 ng/g–1), detritivorous (136.04 ng/g–1), and herbivorous (70.39 ng/g–1). Fish Hg concentrations exceeding current safe limits (500 ng/g–1) for human consumption were found mainly in the piscivorous species (60%). Significant positive correlation between fish weight and Hg concentration was seen for the piscivorous Serrasalmus spp. (n = 326; r = 0.3977; p < 0.0001), Cichla spp. (n = 125; r = 0.4600; p < 0.0001), and Pimelodus spp. (n = 12; r = 0.8299; p = 0.0008), known locally as Piranha, Tucunaré, and Mandi, respectively. However, a negative correlation was seen for nonpiscivorous Potamorhina latior (n = 30; r –0.3763; p = 0.0404) and Leporinus spp. (n = 44; r = –3987; p = 0.0073), known as Branquinha (detritivorous) and Aracu (omnivorous). Fish-Hg concentrations in the acidic waters (pH range, 4.09–6.31) of the Rio Negro habitat, with its wide gradient of Hg concentrations (3.4–11.9 g/L–1) and DOC (1.85–15.3 mg/L–1)—but no history of gold mining activity—are comparable to other Amazonian rivers. Opportunity fish catches in the Rio Negro habitat show high muscle-Hg derived from natural sources, but no systematic association with site-dependent geochemistry.  相似文献   
43.
OBJECTIVE: To examine the clinical, genetic, and molecular characteristics of a group of MJD patients recently identified in the southernmost state of Brazil, and compare these data with studies from the literature. METHODS: Some 62 individuals from 35 families, mostly of Azorean ancestry, had their clinical data and their MJD1 expanded regions examined. RESULTS: The present patients had an earlier age of onset, on average, than Portuguese-Azorean cases. Their survival, proportion of types, average anticipation, proportion of affected versus non-affected siblings, neurological signs and molecular findings are similar to those observed in patients previously described. Type 1 patients with male transmission showed worse anticipations than type 1 patients with female transmission. Patients with type 1 had also larger CAG expansions than other patients. CONCLUSIONS: The Brazilian origin seemed to affect the age of onset. We also noted that there were no differences other than the neurological between types 2 or 3, since both are similar in age of onset, disease duration and length of CAG repeats. We addressed the question of maintaining or not subtypes 2 and 3 separated, among patients with genetic and geographical backgrounds like the presented patients here.  相似文献   
44.
45.
46.
OBJECTIVE: The aim of this study was to evaluate the effect of the oral dual ET(A)/ET(B) receptor antagonist bosentan on different surrogate markers in patients with pulmonary arterial hypertension (PAH). DESIGN AND SETTING: Prospective, open label, uncontrolled study in a University Hospital in Brazil. POPULATION: Fifteen PAH patients (11 females) with mean age of 40 +/- 11 years (5 in WHO functional class II, 10 in class III). METHODS: All patients were investigated at baseline and after 16 weeks of bosentan treatment. We used the following surrogate markers for patients' evaluation: 6-min walk test, quality of life questionnaire (Short Form SF-36) and N-terminal proBNP (B type natriuretic peptide) fraction levels in blood. RESULTS: Between the evaluation at baseline and week 16, the 6-min walk test distance changed from 396 +/- 135 to 434 +/- 137 m (p < 0.05). Each of the eight domains of the SF-36 was significantly improved. Mean NT-proBNP levels were decreased from a mean of 1670 pg/mL to 1010 pg/mL (p = 0.01). CONCLUSION: The study suggests that bosentan treatment results in the improvement of different kinds of surrogate markers independently of their specificity to reflect functional capacity, quality of life and myocardial stress. It is concluded that the combined use of these different markers may be an alternative endpoint for future short duration clinical trials.  相似文献   
47.
陈旭  王文甫 《医学争鸣》2000,21(9):1075-1075
1 临床资料1.1 一般资料  1986 / 1997收治颅内蛛网膜囊肿 34(男 2 8,女 6 )例 .年龄 3~ 6 8岁 ,其中 16岁以下 17例 .有头部外伤史者 15例 ,无明显诱因者 19例 .病程 :2 m o~ 14a.头部外伤至发病时间 :7d~ 2 a. 34例中幕上 30例 ,幕下 4例 ,其中侧裂池 15例 .1.2 临床症状 表现头疼、头昏或伴呕吐、视力下降、视乳头水肿等颅内压增高的症状 18例 ,癫痫发作 7例 ,偏瘫 6例 ,行走不稳 2例 ,失语 1例 .1.3 辅助检查 本组 2 8例作 CT检查 ,6例行 MRI检查证实 .头颅 CT扫描特征 :脑实质外有一边界清楚的低密度病灶 ,CT值与脑脊液…  相似文献   
48.
ABSTRACT

Objective: Fruits and vegetables contain many compounds presenting potential antioxidant activity. The objective of this study was to evaluate the effect of a green juice recipe in adult metabolism in order to identify new preventive dietary sources.

Method: This was a single-blind randomized controlled clinical trial. Recruitment and data were, respectively, made and collected at the Universidade Federal de Ciências da Saúde de Porto Alegre. Individuals who met all the inclusion criteria during the period of recruitment were included. Green juice (experimental group) or placebo (control group) were consumed from Monday to Friday between 8 and 9 am, in the amount of 300 mL for 60 days (except Saturdays and Sundays). To verify the effect of green juice on metabolism, the following were evaluated: (a) glycemia, plasma lipid profile, renal and liver functions, redox profile, and antioxidant enzymes; (b) anthropometry; and (c) well-being and anxiety.

Results: This study included 14 participants in the test group (juice group) and 13 controls (placebo group), with mean ages of 31.07 and 30.15 years, respectively. We did not observe a significant difference between the treatments. Dietary properties of vegetable and fruit juices are an area of significant interest.

Conclusions: Together with an analysis of previous works, we suggest that green juice did not cause an improvement in metabolic function and there is a need for further research on this issue, mainly through different interventions and other samples.  相似文献   
49.

OBJECTIVE

To analyze the evolution of catastrophic health expenditure and the inequalities in such expenses, according to the socioeconomic characteristics of Brazilian families.

METHODS

Data from the National Household Budget 2002-2003 (48,470 households) and 2008-2009 (55,970 households) were analyzed. Catastrophic health expenditure was defined as excess expenditure, considering different methods of calculation: 10.0% and 20.0% of total consumption and 40.0% of the family’s capacity to pay. The National Economic Indicator and schooling were considered as socioeconomic characteristics. Inequality measures utilized were the relative difference between rates, the rates ratio, and concentration index.

RESULTS

The catastrophic health expenditure varied between 0.7% and 21.0%, depending on the calculation method. The lowest prevalences were noted in relation to the capacity to pay, while the highest, in relation to total consumption. The prevalence of catastrophic health expenditure increased by 25.0% from 2002-2003 to 2008-2009 when the cutoff point of 20.0% relating to the total consumption was considered and by 100% when 40.0% or more of the capacity to pay was applied as the cut-off point. Socioeconomic inequalities in the catastrophic health expenditure in Brazil between 2002-2003 and 2008-2009 increased significantly, becoming 5.20 times higher among the poorest and 4.17 times higher among the least educated.

CONCLUSIONS

There was an increase in catastrophic health expenditure among Brazilian families, principally among the poorest and those headed by the least-educated individuals, contributing to an increase in social inequality.  相似文献   
50.
Depression, a multifactorial neuronal disorder with high morbidity/mortality, is associated with psychological, psychosocial, hereditary, and environmental etiologies, where reactive species exert pathophysiological functions. Anacardic acid (AA), a natural compound obtained from cashew nut liquid, has several pharmacological activities, including antioxidant and anticonvulsant. The aim of the present study was to evaluate the antidepressant‐like effect of AA and the involvement of serotonergic, noradrenergic, and L‐arginine–nitric oxide (NO) in tail suspension and forced swim tests and, more so, to investigate its antioxidant effect in Saccharomyces cerevisiae and in male Swiss mice (n = 8). In order to identify the antidepressant mechanisms, AA (10, 25, or 50 mg/kg, p.o.) was given 30 min before clonidine (2‐adrenergic receptor agonist), L‐arginine (NO precursor), propranolol (β‐adrenergic receptor antagonist), and several other agonists or antagonists used. On the other hand, clonidine, noradrenoreceptor, noradrenaline, and L‐arginine were used to identify the antidepressant mechanisms. Results suggest that AA exerts antidepressant‐like activity, especially at higher doses, possibly by inhibiting serotonin and 5HT‐1A reuptake receptors and by inhibiting NO synthetase and guanylyl cyclase enzymes. Additionally, AA exhibited antioxidant effect in S. cerevisiae. This antioxidant capacity may be linked to its antidepressant‐like effect but does not interact with α‐ and β‐adrenoceptor receptors. In conclusion, AA may be used as a promising agent to treat depression, especially which arises from oxidative stress.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号