全文获取类型
收费全文 | 174篇 |
免费 | 14篇 |
国内免费 | 7篇 |
专业分类
儿科学 | 5篇 |
基础医学 | 14篇 |
口腔科学 | 4篇 |
临床医学 | 9篇 |
内科学 | 20篇 |
皮肤病学 | 30篇 |
神经病学 | 2篇 |
特种医学 | 1篇 |
外科学 | 5篇 |
综合类 | 21篇 |
预防医学 | 22篇 |
药学 | 27篇 |
中国医学 | 32篇 |
肿瘤学 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 8篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 7篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有195条查询结果,搜索用时 0 毫秒
31.
Trimethylamine N-oxide (TMAO) and its precursors, including choline, betaine, and L-carnitine, are gut microbiota-related metabolites associated with the risk of obesity. We aimed (1) to comprehensively examine whether the changes in plasma TMAO and its precursors induced by lifestyle intervention are associated with the improvements in plasma metabolic parameters; and (2) to identify the fecal microbiome profiles and nutrient intakes associated with these metabolites and metabolic index. Data from 40 participants (obese children and adolescents) having the plasma metabolites data related to the changes in BMI z-scores after 6-month lifestyle intervention were analyzed. In this study, we observed that choline and the betaine-to-choline ratio (B/C) showed different patterns depending on the changes in BMI z-scores by the response to lifestyle intervention. During the 6 months, an increase in choline and a decrease in B/C were observed in non-responders. We also found that changes in choline and B/C were associated with the improvements in plasma lipid levels. Individuals who showed reduced choline or increased B/C from the baseline to 6 months had a significant decrease in LDL-cholesterol over 6 months compared to those with increased choline or decreased B/C, respectively. In addition, the increase in choline or decrease in B/C was associated with the increase in plasma triglycerides. The distribution of gut microbiota belonging to the Firmicutes, such as Clostridia, Clostridiales, Peptostreptococcaceae, Romboutsia, and Romboutsia timonensis was altered to be lower during the 6 months both as choline decreased and B/C increased. Moreover, the decrease in choline and the increase in B/C were associated with reduced fat intake and increased fiber intake after the 6-month intervention. Finally, lower abundance of Romboutsia showed the association with lower LDL-cholesterol and higher intake of fiber. In summary, we demonstrated that reduced choline and increased B/C by lifestyle intervention were associated with the improvements of LDL-cholesterol and triglycerides, low-fat and high-fiber intakes, and low abundance of Firmicutes. These indicate that changes to circulating choline and B/C could predict individuals’ changes in metabolic compositions in response to the lifestyle intervention. 相似文献
32.
目的 研究甜菜碱对HepG2人肝癌细胞周期及细胞凋亡的影响.方法 MTT法测定甜菜碱对HepG2的细胞毒作用;PI染色,流式细胞术观察甜菜碱对HepG2人肝癌细胞周期及细胞凋亡的影响.结果 甜菜碱对HepG2细胞的IC50为0.5mol/L;甜菜碱使HepG2细胞G2/M期比例下降;甜菜碱作用于HepG2细胞24h后,3个不同剂量组(0.1、0.2、0.4mol/L)诱导细胞凋亡率分别为(7.5±0.9)%、(11.5±1.1)%、(33.9±1.2)%,48h后凋亡率为(13.4±1.9)%、(20.9±1.4)%、(67.8±1.8)%.结论 甜菜碱可抑制人肝癌细胞HepG2的生长,阻滞细胞进入G2/M期进而诱导细胞凋亡. 相似文献
33.
Mikheil Gogiashvili Salome Horsch Rosemarie Marchan Kathrin Gianmoena Cristina Cadenas Berno Tanner Sabrina Naumann Diana Ersova Frank Lippek Jörg Rahnenführer Jan T. Andersson Roland Hergenröder Jörg Lambert Karolina Edlund 《NMR in biomedicine》2018,31(2)
High‐resolution magic angle spinning (HR MAS) nuclear magnetic resonance (NMR) spectroscopy is increasingly being used to study metabolite levels in human breast cancer tissue, assessing, for instance, correlations with prognostic factors, survival outcome or therapeutic response. However, the impact of intratumoral heterogeneity on metabolite levels in breast tumor tissue has not been studied comprehensively. More specifically, when biopsy material is analyzed, it remains questionable whether one biopsy is representative of the entire tumor. Therefore, multi‐core sampling (n = 6) of tumor tissue from three patients with breast cancer, followed by lipid (0.9‐ and 1.3‐ppm signals) and metabolite quantification using HR MAS 1H NMR, was performed, resulting in the quantification of 32 metabolites. The mean relative standard deviation across all metabolites for the six tumor cores sampled from each of the three tumors ranged from 0.48 to 0.74. This was considerably higher when compared with a morphologically more homogeneous tissue type, here represented by murine liver (0.16–0.20). Despite the seemingly high variability observed within the tumor tissue, a random forest classifier trained on the original sample set (training set) was, with one exception, able to correctly predict the tumor identity of an independent series of cores (test set) that were additionally sampled from the same three tumors and analyzed blindly. Moreover, significant differences between the tumors were identified using one‐way analysis of variance (ANOVA), indicating that the intertumoral differences for many metabolites were larger than the intratumoral differences for these three tumors. That intertumoral differences, on average, were larger than intratumoral differences was further supported by the analysis of duplicate tissue cores from 15 additional breast tumors. In summary, despite the observed intratumoral variability, the results of the present study suggest that the analysis of one, or a few, replicates per tumor may be acceptable, and supports the feasibility of performing reliable analyses of patient tissue. 相似文献
34.
Manan Bhatt Angela Di Iacovo Tiziana Romanazzi Cristina Roseti Elena Bossi 《Basic & clinical pharmacology & toxicology》2023,133(5):485-495
The role of betaine in the liver and kidney has been well documented, even from the cellular and molecular point of view. Despite literature reporting positive effects of betaine supplementation in Alzheimer's, Parkinson's and schizophrenia, the role and function of betaine in the brain are little studied and reviewed. Beneficial effects of betaine in neurodegeneration, excitatory and inhibitory imbalance and against oxidative stress in the central nervous system (CNS) have been collected and analysed to understand the main role of betaine in the brain. There are many ‘dark’ aspects needed to complete the picture. The understanding of how this osmolyte is transported across neuron and glial cells is also controversial, as the expression levels and functioning of the known protein capable to transport betaine expressed in the brain, betaine-GABA transporter 1 (BGT-1), is itself not well clarified. The reported actions of betaine beyond BGT-1 related to neuronal degeneration and memory impairment are the focus of this work. With this review, we underline the scarcity of detailed molecular and cellular information about betaine action. Consequently, the requirement of detailed focus on and study of the interaction of this molecule with CNS components to sustain the therapeutic use of betaine. 相似文献
35.
目的?观察地骨皮中有效成分对高糖刺激的肾小球系膜细胞的增殖以及细胞外基质分泌的影响,研究其对糖尿病肾病的保护机制。方法?体外培养肾小球系膜细胞,分为高糖模型组(葡萄糖浓度为30?mmol/L),空白对照组(葡萄糖浓度为5.5?mmol/L),甜菜碱、山奈酚5个浓度剂量组(0.01、0.1、1、10、100?μmol/L),用MTT法观察系膜细胞增殖情况,ELISA法观察细胞外基质分泌情况。结果?与高糖模型组比较,不同剂量甜菜碱组和山奈酚组,对高糖致肾小球系膜细胞增殖有不同程度的抑制。甜菜碱、山奈酚均能抑制细胞外基质的分泌,与高糖模型组比较有显著性差异(P<0.05~0.01)。结论?地骨皮中有效成分甜菜碱和山奈酚均具有抑制高糖刺激下系膜细胞增殖以及细胞外基质分泌的作用,推测地骨皮中有效成分具有治疗糖尿病肾病的作用。 相似文献
36.
37.
The ability of betaine to reduce the irritating effects of detergents assessed visually, histologically and by bioengineering methods 总被引:1,自引:0,他引:1
Ingrid Nicander Irma Rantanen Barbro Lundh Rozell Eva Söderling Stig Ollmar 《Skin research and technology》2003,9(1):50-58
Background/aims: A novel approach for reducing the undesired irritating properties of detergents on skin might be offered by betaine, which is a natural product derived from the sugar beet. The aim of the study was to explore the ability of betaine to reduce the irritating effects of two surfactants, sodium lauryl sulphate (SLS) and cocoamidopropylbetaine (CAPB). For evaluation of changes in skin reactions visual scoring, electrical impedance, transepidermal water loss and histology were used.
Methods: Twenty-one healthy subjects were patch tested for 24 h with SLS and CAPB alone and together with betaine, betaine alone, and the two controls distilled water and an unoccluded test site on both volar forearms. Responses were evaluated by measuring electrical impedance and transepidermal water loss before exposure and 24 h after the removal of the test substances, and also by visual inspection and histology. The electrical impedance device enables measurements at 31 frequencies and relevant information was extracted from the spectra using four indices.
Results: CAPB was found to be less irritating than SLS. The used detergents gave rise to distinctive impedance patterns also reflected by different types of histopathological skin responses. After the adding of betaine, the irritant reaction decreased for both detergents.
Conclusions: Betaine is a promising ingredient to reduce the side effects of detergents and electrical impedance is a suitable tool both to quantify the degree of irritation as well as to differentiate between various types of reactions. 相似文献
Methods: Twenty-one healthy subjects were patch tested for 24 h with SLS and CAPB alone and together with betaine, betaine alone, and the two controls distilled water and an unoccluded test site on both volar forearms. Responses were evaluated by measuring electrical impedance and transepidermal water loss before exposure and 24 h after the removal of the test substances, and also by visual inspection and histology. The electrical impedance device enables measurements at 31 frequencies and relevant information was extracted from the spectra using four indices.
Results: CAPB was found to be less irritating than SLS. The used detergents gave rise to distinctive impedance patterns also reflected by different types of histopathological skin responses. After the adding of betaine, the irritant reaction decreased for both detergents.
Conclusions: Betaine is a promising ingredient to reduce the side effects of detergents and electrical impedance is a suitable tool both to quantify the degree of irritation as well as to differentiate between various types of reactions. 相似文献
38.
Contact dermatitis to rhodium 总被引:1,自引:0,他引:1
39.
F-f Zeng C-h Xu Y-t Liu Y-y Fan X-l Lin Y-k Lu C-x Zhang Y-m Chen 《British journal of cancer》2014,110(3):808-816
Background:
Intakes of choline and betaine have been inversely related to the risk of various neoplasms, but scant data exist on nasopharyngeal carcinoma (NPC). We examined the association between consumption of choline and betaine and risk of NPC.Methods:
We conducted a case–control study with 600 incident NPC patients and 600 controls 1 : 1 matched by age, sex and household type in Guangdong, China. Dietary intake was assessed by a food frequency questionnaire through face-to-face interview.Results:
Intakes of total choline, betaine and choline+betaine were inversely related to NPC after adjustment for various lifestyle and dietary factors (all P-trend <0.001). Adjusted odds ratios (95% CI) for quartile 4 (vs quartile 1) were 0.42 (0.29, 0.61) for total choline, 0.50 (0.35, 0.72) for betaine and 0.44 (0.30, 0.64) for betaine+total choline. Regarding various sources of choline, lower NPC risk was associated with greater intakes of choline from phosphatidylcholine, free choline, glycerophosphocholine and phosphocholine, but not sphingomyelin.Conclusion:
These findings are consistent with a beneficial effect of choline and betaine intakes on carcinogenesis. 相似文献40.
甜菜碱促进小鼠脾淋巴细胞增殖作用的钙通道机制研究 总被引:1,自引:0,他引:1
目的:研究甜菜碱促进小鼠脾淋巴细胞的增殖作用与钙通道的关系.方法:采用清洁级BALB/c小鼠分离小鼠脾淋巴细胞后体外培养的方式获得小鼠脾淋巴细胞,分为阴性对照组、Con A组、甜菜碱0.04,0.4,4,20 mmol·L~(-1)组.分别采用MTT法观察甜菜碱对小鼠脾淋巴细胞增殖的作用,流式细胞术测定甜菜碱对小鼠脾淋巴细胞周期的变化,激光共聚焦扫描显微镜观察甜菜碱对小鼠脾淋巴细胞内钙浓度的变化及加入不同钙通道阻滞剂后细胞内钙浓度的变化.结果:4,20 mmol·L~(-1)甜菜碱体外作用于小鼠脾淋巴细胞12 h促进小鼠脾淋巴细胞增殖,0.04,0.4,4,20 mmol·L~(-1)甜菜碱分别体外作用于小鼠脾淋巴细胞24,48 h均促进小鼠脾淋巴细胞增殖,以4 mmol·L~(-1)甜菜碱作用24 h效果最好;4 mmol·L~(-1)甜菜碱作用小鼠脾淋巴细胞4,6,18,24 h能促使小鼠脾淋巴细胞由G_0/G_1期进入S期,并以18 h效果最为明显;4 mmol·L~(-1)甜菜碱作用于淋巴细胞6,12,18 h,脾淋巴细胞内Ca~(2+)浓度明显升高(P<0.01),以6 h效果最明显;钙通道阻滞剂硝苯地平、地尔硫卓、咪贝地尔、金雀异黄素对甜菜碱升高小鼠脾淋巴细胞内钙离子浓度没有影响,而维拉帕米、新霉素、肝素、普鲁卡因能阻断甜菜碱升高小鼠脾淋巴细胞内钙离子浓度.结论:甜菜碱通过升高小鼠脾淋巴细胞内钙离子浓度而促进小鼠脾淋巴细胞由G_0/G_1期进入S期,促小鼠脾淋巴细胞增殖的作用.细胞内钙离子浓度升高主要通过2个途径:影响G蛋白介导的L-型电压门控钙通道的α_1亚单位而引起外钙内流;影响胞内钙库的IP_3R钙通道和RyR钙通道而引起内钙释放. 相似文献