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   20228篇
  免费   1492篇
  国内免费   1132篇
耳鼻咽喉   18篇
儿科学   624篇
妇产科学   209篇
基础医学   1718篇
口腔科学   140篇
临床医学   1488篇
内科学   5769篇
皮肤病学   200篇
神经病学   1051篇
特种医学   404篇
外科学   808篇
综合类   2452篇
现状与发展   7篇
预防医学   3030篇
眼科学   109篇
药学   2974篇
  5篇
中国医学   1424篇
肿瘤学   422篇
  2024年   59篇
  2023年   531篇
  2022年   1011篇
  2021年   1162篇
  2020年   927篇
  2019年   770篇
  2018年   693篇
  2017年   701篇
  2016年   789篇
  2015年   796篇
  2014年   1350篇
  2013年   1507篇
  2012年   1060篇
  2011年   1248篇
  2010年   829篇
  2009年   802篇
  2008年   840篇
  2007年   787篇
  2006年   703篇
  2005年   608篇
  2004年   487篇
  2003年   410篇
  2002年   388篇
  2001年   305篇
  2000年   280篇
  1999年   239篇
  1998年   242篇
  1997年   235篇
  1996年   206篇
  1995年   187篇
  1994年   197篇
  1993年   194篇
  1992年   161篇
  1991年   139篇
  1990年   161篇
  1989年   166篇
  1988年   148篇
  1987年   120篇
  1986年   115篇
  1985年   157篇
  1984年   154篇
  1983年   108篇
  1982年   137篇
  1981年   111篇
  1980年   117篇
  1979年   88篇
  1978年   81篇
  1977年   65篇
  1976年   74篇
  1973年   50篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
961.
目的通过研究阿托伐他汀对自发性高血压大鼠(SHR)心肌中PPARα、CPTⅠ表达和心肌脂质代谢变化及心肌肥厚指标的影响,探讨阿托伐他汀对SHR心肌肥厚的改善作用及其机理。方法观察阿托伐他汀灌胃10周的SHR心肌肥厚指标、血清和心肌游离脂肪酸含量及心肌PPARα、CPTⅠmRNA表达的改变。结果与WKY(n=6)比较,SHR(n=6)心肌中PPARαmRNA(0.285±0.062比WKY:0.478±0.093,P<0.01)与CPTⅠmRNA(0.795±0.139比WKY:1.115±0.109,P<0.01)表达减少,血清及心肌中游离脂肪酸含量增加,分别为[(798.2±38.0比WKY:354.7±27.7)nmol/L,P<0.01]和[(635.0±77.4比WKY:245.3±47.3)nmol/L,P<0.01],心室质量指数增加(VWI)[(3.16±0.08比WKY:2.99±0.10)g/kg,P<0.05],心肌细胞直径增加(TDM)[(21.3±1.3比WKY:18.18±0.75)μm,P<0.01];阿托伐他汀50mg/kg·d治疗10周后(n=6),心肌中PPARα、CPTⅠmRNA表达增加,心肌中游离脂肪酸含量明显降低、VWI降低,TDM降低。结论阿托伐他汀能够增加心肌中PPARα、CPTⅠmRNA表达,降低心肌中游离脂肪酸含量,改善心肌脂质代谢障碍,可能是其抑制心肌肥厚发生与发展的机制之一。  相似文献   
962.
Purpose Altered redox status has been implicated in pathogenesis of alcoholic liver disease (ALD) as well as in nonalcoholic fatty liver disease (NAFLD). This study was planned to find the relative role of redox status in these two diseases. Methods A total of 44 patients with ALD and 32 patients with NAFLD and 25 apparently healthy controls were included in the study. Redox status was estimated by measuring oxidative stress (superoxide dismutase (SOD) and lipid peroxidation products as thiobarbituric acid reactive substances (TBARS)) and antioxidant status (ferric reducing ability of plasma (FRAP) and vitamin C). Results TBARS level was raised significantly in both ALD (3.5 (2.3–9.4) vs. 1.8 (0.5–4.1) nmol/ml; P = 0.0001) and NAFLD (5.1 (1–10.2) vs. 1.82 (0.51–4.1) nmol/ml; P = 0.0001) as compared with controls, but was not different between ALD and NAFLD. SOD was significantly higher in ALD as compared to NAFLD (2.4 (1.3–7.8) vs. 0.68 (0.05–19.1) U/ml; P = 0.0001) and controls (1.12 (0.01–3.5) U/ml; P = 0.001). FRAP was lower in ALD as compared with NAFLD (345.4 (56–615.9) vs. 434.1 (197.6–733.3) μmol of Fe+2 liberated; P = 0.001) but similar to that of controls (340.9 (141.5–697.5) μmol of Fe+2 liberated). Conclusions ALD patients have a higher degree of redox imbalance as compared with NAFLD patients  相似文献   
963.
Obesity is a principal risk factor for type 2 diabetes, and elevated fatty acids reduce beta-cell function and survival. An unbiased proteomic screen was used to identify targets of palmitate in beta-cell death. The most significantly altered protein in both human islets and MIN6 beta-cells treated with palmitate was carboxypeptidase E (CPE). Palmitate reduced CPE protein levels within 2 h, preceding endoplasmic reticulum (ER) stress and cell death, by a mechanism involving CPE translocation to Golgi and lysosomal degradation. Palmitate metabolism and Ca(2+) flux were also required for CPE proteolysis and beta-cell death. Chronic palmitate exposure increased the ratio of proinsulin to insulin. CPE null islets had increased apoptosis in vivo and in vitro. Reducing CPE by approximately 30% using shRNA also increased ER stress and apoptosis. Conversely, overexpression of CPE partially rescued beta-cells from palmitate-induced ER stress and apoptosis. Thus, carboxypeptidase E degradation contributes to palmitate-induced beta-cell ER stress and apoptosis. CPE is a major link between hyperlipidemia and beta-cell death pathways in diabetes.  相似文献   
964.
BACKGROUND: Non-alcoholic fatty liver disease (NAFLD), a common entity in the general population, has been shown to be linked with insulin resistance and metabolic syndrome. Several of the components of the metabolic syndrome are more common in the aged population. The aims of the current study were to determine in the aged, the prevalence and the clinical presentation of NAFLD, as well as the relation to the underlying metabolic abnormalities. METHOD: In this prospective study, we evaluated 91 octogenarians with a mean age of 85.56+/-3.76 years, who were admitted to the rehabilitation departments of a geriatric hospital. Clinical evaluation included: abdominal ultrasound (US), fasting glucose and lipid levels, serum liver enzymes, ferritin, iron and transferrin saturation. Elderly patients with NAFLD were compared with 46 young patients with NAFLD. RESULTS: NAFLD diagnosed by US was a common finding in this aged population, is present in 42/91 patients (46.2%). No significant differences were observed between the patients with or without NAFLD in the following: age, gender, chronic illnesses, anthropometric parameters, lipid profile, fasting glucose levels, metabolic syndrome prevalence, serum levels of transaminases, ferritin and iron. Young patients with NAFLD had significantly higher serum levels of triglycerides and a significantly higher prevalence of glucose intolerance, obesity and the metabolic syndrome compared with the elderly patients with NAFLD. CONCLUSIONS: NAFLD was a common finding in our group of elderly patients and the prevalence was higher than reported in the general population. In contrast to the well-described association between the metabolic syndrome and NAFLD in the general population, we did not find this association in the aged group. In addition, none of the patients had stigmata of advanced liver disease. These data suggest that NAFLD is a common and benign finding in the elderly population, but is not associated with the metabolic syndrome.  相似文献   
965.
BACKGROUND: In murine models of inflammatory bowel disease, colonic inflammation is considered to be caused by an aberrant Th1-type immune response. AIM: To investigate if systemic administration of interleukin (IL)-12 and IL-18 to wild-type BALB/c mice induces liver injury and intestinal inflammation, and if pathological changes are observed, what cytokines are involved. METHODS: Mice (BALB/c-wild-type (wt), MRL-lpr/lpr, BALB/c-interferon gamma knock out (IFN-gamma KO), C57BL/6-inducible nitric oxide synthase (iNOS) KO, and BALB/c tumour necrosis factor alpha (TNF-alpha) KO) were injected intraperitoneally each day with IL-12 (20 ng/g/mouse) and/or IL-18 (200 ng/g/mouse). RESULTS: Administration of IL-12 and IL-18 to BALB/c-wt mice induced prominent intestinal mucosal inflammation and fatty liver, leading to piloerection, bloody diarrhoea, and weight loss. IL-12 and IL-18 induced striking elevations in serum levels of IFN-gamma that caused NO production, although increased NO had no exacerbating effect on mice. Moreover, iNOS KO mice, or MRL lpr/lpr mice lacking functional Fas were equally susceptible to IL-12 and IL-18. Administration of IL-12 and IL-18 did not induce TNF-alpha production in wild-type mice, and the same treatment to TNF-alpha KO mice induced intestinal mucosal inflammation. Furthermore, they had diffuse and dense infiltration of small fat droplets in their hepatocytes associated with an increase in serum levels of liver enzymes. In contrast, the same treatment in IFN-gamma KO BALB/c mice and iNOS KO mice did not induce these changes. CONCLUSIONS: Our study strongly indicates that IL-18 together with IL-12 induces intestinal mucosal inflammation in an IFN-gamma dependent but TNF-alpha, NO, and Fas ligand independent manner, and fatty liver is dependent on IFN-gamma and NO.  相似文献   
966.
BACKGROUND: An adequate energy-protein intake (EPI) when combined with amino acid supplementation may have a positive impact on nutritional and metabolic status in patients with chronic heart failure (CHF). METHODS AND RESULTS: Thirty eight stable CHF patients (27 males, 73.5+/-4 years; BMI 22.5+/-1.4 kg/m2), with severe depletion of muscle mass and were randomised to oral supplements of essential amino acids 8 g/day (EAA group; n=21) or no supplements (controls; n=17). All patients had adequate EPI (energy> or =30 kcal/kg; proteins >1.1 g/kg). At baseline and 2-months after randomisation, the patients underwent metabolic (plasma lactate, pyruvate concentration; serum insulin level; estimate of insulin resistance by HOMA index), nutritional (measure of nitrogen balance), and functional (exercise test, walking test) evaluations. Body weight increased by >1 kg in 80% of supplemented patients (mean 2.96 kg) and in 30% of controls (mean 2.3 kg) (interaction <0.05). Changes in arm muscle area, nitrogen balance, and HOMA index were similar between the two treatment groups. Plasma lactate and pyruvate levels increased in controls (p<0.01 for both) but decreased in the supplemented group (p<0.01 and 0.02 respectively). EAA supplemented patients but not controls improved both exercise output and peak oxygen consumption and walking test. CONCLUSIONS: Adequate EPI when combined with essential amino acid supplementation may improve nutritional and metabolic status in most muscle-depleted CHF patients.  相似文献   
967.

Background

Metabolic syndrome is a multisystem disorder which coined to describe the recognized clustering of metabolic and cardiovascular abnormalities including obesity, hypertension, dyslipidemia, and abnormalities of glucose homeostasis.

Objective

To assess the prevalence and associated factors of metabolic syndrome among psychiatric patients in Jimma University Specialized Hospital.

Methods

This study was conducted at Jimma University Specialized hospital psychiatric ward from May 15 to July 16, 2015. A cross-sectional study design and consecutive sampling technique were used. A single population proportion formula was used to include a total of 360 psychiatric patients. An interview administered structured questionnaire was used to collect socio-demographic and some clinical data. Anthropometric data were collected based on standard guild line for anthropometric measurement. Five milliliter of venous blood was collected from ante-cubital fossa after overnight fasting for 8?h. Semi-automated clinical chemistry analyzer (Temis Linear) was used for biochemical laboratory analysis. Data analysis was performed by using SPSS version-20 software. Binary and multiple logistic regressions were used to identify the association between dependent and independent variables. P value less than 0.05 was taken as statistically significant association.

Results

The prevalence of metabolic syndrome among psychiatric patients was 28.9%. Age greater than 30 years old (AOR: 5.2, CI: 2.3, 11.8, P. value?<?0.05); being female (AOR: 7.1, CI: 3.3, 15.2, P. value?<?0.05); regularly eating high protein and fat (AOR: 3.3, CI: 1.3, 8.2, P. value?<?0.056) were independent determinant variables for high prevalence of metabolic syndrome among diabetic patients in the study area. The other independent variables such as family history of hypertension, chewing chat, Psychotropic drugs, duration of treatment, regularly eating fruits and vegetables had no statistically significant association with metabolic syndrome (P. value?>?0.05).

Conclusion and recommendation

There was high prevalence of metabolic syndrome among the psychiatric patients. Therefore; close assessment, management and treatment of metabolic syndrome among patients with psychiatry problem is essential.  相似文献   
968.
非酒精性脂肪性肝病(NAFLD)是代谢综合征在肝脏的病理学表现。由于饮食结构的改变,NAFLD发病率呈现上升趋势,且NAFLD与肝病进展、糖尿病和心血管疾病死亡密切相关。因此,寻求NAFLD患者综合管理方法迫在眉睫。本文综述了NAFLD分级、分期、治疗和随访评估的研究进展,以期指导临床诊断、治疗和管理。  相似文献   
969.
970.
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