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排序方式: 共有275条查询结果,搜索用时 156 毫秒
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In this work, a mesoporous silica microsphere (MSM) was selected as a support to prepare a bimetallic supported catalyst (15% W–5% Ni/MSM) by a co-impregnation method that was simple and easy to conduct. We wished to improve the capability of catalytic conversion of biomass into ethylene glycol (EG) and 1,2-propylene glycol (1,2-PG). 15% W–5% Ni/MSM was examined on microcrystalline cellulose (cellulose) and corn stalks in a one-pot catalytic process, and total yields of EG and 1,2-PG reached up to 82.40 wt% and 62.60 wt%, respectively. This remarkable catalytic performance of W–Ni/MSM catalyst could be attributed to the synergistic effect between the active sites of Ni and W and the unique structure of MSM, which was suitable for mass transfer and metal loading. Based on physicochemical characterizations, the metal component was well-distributed on the surface of the MSM, and the metallic Ni, W and WO3 of the fresh catalyst were converted mainly into NiWO4 during the catalytic conversion of cellulose. To shed light on the reaction mechanism of the catalyzed hydrogenation of biomass, a possible process involving the formation of HxWO3 homogeneous catalysts, cellulose hydrolysis, C–C cleavage and hydrogenation conversion to 1,2-PG and EG was illustrated. Furthermore, the reusability of W–Ni/MSM catalyst was tested and we explored the cause of decreased diols yields. In summary, this work provides important guidance to rationally design effective catalysts for biomass conversion.Bimetallic supported catalyst (W-Ni/MSM) was proposed to improve capability of catalytic conversion and investigated reaction pathway of lignocellulose into ethylene glycol and 1,2-propylene glycol. 相似文献
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Liu F Li B Wang WT Wei YG Yan LN Wen TF Xu MQ Yang JY 《World journal of gastroenterology : WJG》2012,18(8):847-854
AIM: To investigate the association between interleukin (IL)-10-1082 (G/A) promoter polymorphism and acute rejection (AR) in liver transplant (LT) recipients.METHODS: Two investigators independently searched the Medline, Embase, China National Knowledge Infrastructure, and Chinese Biomedicine Databases. Summary odds ratios (ORs) and 95% CIs for IL-10-1082 G/A polymorphism and AR were calculated in a fixed- and a random-effects model as appropriate.RESULTS: This meta-analysis included seven case-control studies, which comprised 652 cases of LT recipients in which 241 cases developed AR and 411 cases did not develop AR. Overall, the variant A allele was not associated with AR risk when compared with the wild-type G allele (OR = 0.94, 95% CI: 0.64-1.39). Moreover, similar results were observed when the AA genotype was compared with the AG/GG genotype (OR = 1.05, 95% CI: 0.55-2.02). When stratifying for ethnicity, no significant association was observed among either Caucasians or Asians. Because only one study was performed in Asian patients, the result of subgroup analysis by ethnicity would not be reliable for Asians. Limiting the analysis to the studies with controls in the Hardy-Weinberg equilibrium, the results were persistent and robust. No publication bias was found in the present study.CONCLUSION: This meta-analysis suggests that IL-10-1082 G/A polymorphism may be not associated with AR risk in LT recipients among Caucasians. 相似文献
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The aim of the randomised trial was to compare conventional semen parameters, sperm DNA fragmentation levels and satisfaction levels between semen samples collected at home and at the clinic. We recruited 110 men with a history of infertility for at least 1 year from the outpatient andrology clinic. Each man collected two semen samples, one at home and one at the clinic. Men were randomly assigned into the home first (n = 55) or clinic first (n = 55) groups. The primary outcome was sperm concentration. There was no significant difference in sperm concentration, sperm DNA fragmentation levels or other conventional semen parameters between home first and clinic first samples (p > .05), while satisfaction levels were significantly higher for home first samples (p < .01). Consistent results were obtained when comparing home-collected and clinic-collected samples within individuals. Men can be offered the option to collect semen samples at home for examination or assisted reproduction without compromising semen quality, especially for those with difficulty in producing semen samples at the clinic. 相似文献
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Haitao Wu Jing Gao Xia Wang Tsz Ying Leung Yong-Gang Duan Philip C. N. Chiu 《Andrologia》2020,52(5):e13565
Platelet-activating factor (PAF) affects capacitation, acrosome reaction and fertilisation potential of spermatozoa. This study investigated the underlying mechanism(s) through which PAF regulated sperm function. Our data demonstrated that PAF dose-dependently induced, whilst lyso-PAF (PAF precursor) showed no effect on acrosome reaction of capacitated human spermatozoa. Treatment with PAF for 90 min enhanced tyrosine phosphorylation and expression of extracellular signal-regulated protein kinases (ERK) 1 and 2 in human spermatozoa. Moreover, pre-treatment with the ERK inhibitor U0126 significantly and dose-dependently suppressed PAF-induced acrosome reaction. Therefore, PAF may be actively involved in the modulation of sperm acrosome reaction by interacting with ERK. The role of PAF in fertilisation warrants further investigation. 相似文献
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尾加压素Ⅱ促进大鼠主动脉合成和分泌内皮素1的机制研究 总被引:1,自引:0,他引:1
目的 研究尾加压素Ⅱ刺激大鼠主动脉组织产生和分泌内皮素1的作用及其细胞内信号机制.方法 将大鼠主动脉组织薄片和不同浓度尾加压素Ⅱ(10-10~10-7 mol/L)共孵育3 h或6 h,采用放射免疫法测定组织和孵育液中内皮素1含量;向孵育液中加入不同阻断剂,观察对尾加压素Ⅱ诱导内皮素1合成效应的影响,初步探讨尾加压素Ⅱ作用的细胞内机制.结果 尾加压素Ⅱ明显刺激内皮素1的分泌(孵育液含量)和产生(孵育液和组织内皮素1含量总和),呈现时间和浓度依赖性(10-10~10-7 mol/L).孵育3 h后,尾加压素Ⅱ(10-8 mol/L)组内皮素1分泌量较对照组高1.46倍 (P<0.01),产生总量较对照组高87.9% (P<0.01);孵育6 h后,尾加压素Ⅱ刺激组(浓度分别为10-10、10-9、10-8 mol/L和10-7 mol/L)内皮素1分泌量分别较对照组增加59.2%,108.0%,159.6%和178.0%,产生总量分别较对照组增加40.6%,68.4%,103.1% 和105.7%(P<0.01).尾加压素Ⅱ促进内皮素1产生的作用能分别被Ca2 通道阻断剂尼卡地平、蛋白激酶C阻断剂H7、丝裂素活化蛋白激酶抑制剂PD98059、mRNA抑制剂放线菌素D以及蛋白合成抑制剂环磷酰胺所抑制,其中对内皮素1分泌作用的抑制率分别为34.1%,24.5%,32.2%,32.1%和27.6%(P<0.01),对内皮素1产生总量的抑制率分别为33.5%,31.5%,25.8%,28.0%和36.8%(P<0.01).结论 尾加压素Ⅱ能够促进主动脉组织合成和分泌内皮素1,该作用可通过Ca2 通道、蛋白激酶C以及丝裂素活化蛋白激酶途径来实现,并提示尾加压素Ⅱ的缩血管等效应有可能通过促进内皮素1的产生来实现. 相似文献
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Rui Xue Zeng-Liang Jin Hong-Xia Chen Li Yuan Xin-Hua He Yan-Ping Zhang Yong-Gang Meng Jiang-Ping Xu Jian-Quan Zheng Bo-Hua Zhong Yun-Feng Li You-Zhi Zhang 《European neuropsychopharmacology》2013,23(7):728-741
SNRIs (serotonin and norepinephrine reuptake inhibitors) have been proposed to exert increased therapeutic efficacy or be faster acting compared to commonly used antidepressants. In this study, we performed in vitro binding and uptake assays and in vivo behavioral tests to assess the pharmacological properties and antidepressant-like efficacy of the compound 071031B; we also performed cytotoxicity tests using HepG2 cells and SH-SY5Y cells to predict the toxicity of 071031B. In vitro, 071031B had high affinity for both serotonin transporters and norepinephrine transporters prepared from rat cortex tissue (Ki=2.68 and 1.09 nM, respectively) and recombinant cells (Ki=1.57 and 0.36 nM, respectively). Moreover, 071031B also potently inhibited the uptake of serotonin (5-HT) and norepinephrine (NE) into rat cortical synaptosomes (Ki=1.99 and 1.09 nM, respectively) and recombinant cells (Ki=3.23 and 0.79 nM, respectively). In vivo, acute administration of 071031B dose-dependently reduced the immobility time in the tail suspension test in mice and the forced swimming test in mice and rats with higher efficacy than duloxetine and showed no stimulatory effect on the locomotor activity. Chronic 071031B treatment (5 or 10 mg/kg) significantly reversed depressive-like behaviors in chronically stressed rats, including reduced sucrose preference, decreased locomotor activity, and prolonged latency to begin eating. Furthermore, 071031B also exhibited lower cytotoxicity in HepG2 cells and SH-SY5Y cells in vitro than duloxetine. These findings suggest that 071031B is a novel, balanced serotonin and norepinephrine reuptake inhibitor, with more potent antidepressant effects and lower hepatotoxicity and neurotoxicity in vitro than duloxetine. 相似文献