类肝素聚乳酸微孔膜的血液相容性

通过在生物基聚乳酸(PLA)膜表面进行类肝素化修饰,得到了具有良好血液相容性的生物基聚合物膜。首先通过自由基聚合合成了聚(乙烯基吡咯烷酮–乙烯基三乙氧基硅烷)[P(VP–VTES)]预聚物,进一步通过其界面交联,将高含量的聚乙烯基吡咯烷酮固化到PLA膜表面,提高膜表面的亲水性和抗污性能。其次通过自由基聚合合成类肝素预聚物苯乙烯磺酸钠–乙烯基三乙氧基硅烷–丙烯酸三元共聚物[P(SSNa–VTES–AAH)],并利用预聚物中VTES链段的水解缩合反应将类肝素共聚物固定在PLA膜表面,从而提高膜的血液相容性。通过红外光谱确定了PLA膜表面亲水层P(VP–VTES)和P(SSNa–VTES–AAH)的分子结构。通过接触角测试表明类肝素分子修饰的PLA膜具有良好的亲水性,并可以抑制膜表面血小板的吸附和聚集。同时,凝血测试结果表明类肝素分子修饰的PLA膜表面具有良好的血液相容性

大规模化合物子结构检索的并行实现与优化

化合物的子结构检索在计算机辅助药物设计、波普学、化学数据库等领域是不可或缺的工具。然而由于子结构检索是一个NP完备性的问题,获得用户可接受的平均检索时间一直是研究人员十分关注的问题,其方法主要有改进算法和提升硬件条件2个方面。当化学结构数据库的规模达到百万乃至千万级别时,尽管改进算法的方式能够获得一定的检索效率提升,但其提升的空间有限,因而,集群并行方式是大规模化合物子结构检索应用的必然选择。本文以ChemDB Portal的化学子结构检索系统为基础,实现了基于集群并行的化学子结构检索系统,并进行了任务均分、多线程并行等优化。在包含800万个化合物结构的化学结构数据库中,利用5个节点的小型集群,选取10个较为典型的提问结构进行子结构检索测试。测试结果为基于集群的化学子结构检索的平均检索时间由初始单节点时的34.1 min降低为2.75 min,检索效率平均提高12.4倍,表明在大规模乃至超大规模的数据条件下,集群并行化方式能够显著地提高子结构检索系统的执行效率

Dynamics Analysis on Serpentine Locomotion of a New Snake-like Robot

为提高蛇形机器人执行各种运动的能力,研制了新型蛇形机器人系统.重点研究了该蛇形机器人的动力学.建立了机器人的运动学模型,并根据运动学模型提出了控制蛇形机器人蜿蜒运动的复合运动控制方法.用拉格朗日方法建立动力学模型,对不同参数下蛇形机器人的关节力矩特性和摩擦力特性进行了分析比较,为蛇形机器人的有效运动提供了理论依据

神经网络用于环丙胺类衍生物的构效关系研究

将神经网络应用于定量构效关系研究。用改进的反传算法探讨了单胺氧化酶抑制剂Ｎ－（苯氧乙基）环丙胺取代衍生物的生物活性与取代基电子效应σ、疏水作用π、空间效应Ｅｓ等参数之间的定量关系。给出了精密拟合和准确预测（最大误差均小于１０％），优于经典的多元线性回归及逐步回归方法。作为一种有效的计量化学新方法，神经网络有良好的预测能力和非线性处理功能，从而可望在ＱＳＡＲ研究中发挥重要作用

神经网络用于环丙胺类衍生物的构效关系研究

将神经网络应用于定量构效关系研究。用改进的反传算法探讨了单胺氧化酶抑制剂Ｎ－（苯氧乙基）环丙胺取代衍生物的生物活性与取代基电子效应σ、疏水作用π、空间效应Ｅｓ等参数之间的定量关系。给出了精密拟合和准确预测（最大误差均小于１０％），优于经典的多元线性回归及逐步回归方法。作为一种有效的计量化学新方法，神经网络有良好的预测能力和非线性处理功能，从而可望在ＱＳＡＲ研究中发挥重要作用

化学深层网检索引擎ChemDB Portal的优化与改进

化学深层网检索引擎系统ChemDB Portal是一个利用深层网检索技术在线检索多来源数据库的化学检索引擎。经过几年的开发已经具备了通过不同检索方式,包括名称、分子式、CAS号检索、结构检索等方式,实时在线检索多来源网络数据库的功能,实现了化合物数据信息的多途径集成检索和利用

利用ChemDB Portal检索化学深层网

<正>Internet的普及为专业人员获取数据信息、利用计算工具提供了统一的平台,检索网络化学信息资源的工具也从化学浅层网向化学深层网发展。中国科学院过程工程研究所高性能计算

亚洲中部干旱区3个典型生态系统生长季水碳通量特征/Characteristics of water and carbon fluxes during growing season in three typical arid ecosystems in central Asia[J]

亚洲中部干旱区地处欧亚大陆腹地,干旱少雨,生态环境十分脆弱,研究该地区大气与地表之间的能量和物质交换对干旱区水资源利用和生态环境保护具有重要意义.该文分析了亚洲中部干旱区荒漠与草地生态系统能量、水汽和CO2通量的日变化及季节变化特征,探究了水汽和CO2通量对主要环境因子的响应.通过分析亚洲中部干旱区3个站点的涡度相关资料发现:亚洲中部干旱区荒漠和草地生态系统在生长季(4-10月)能量、水汽通量、净CO2通量和总初级生产力的日变化呈“单峰型”,而荒漠生态系统呼吸日变化相对稳定;草地生态系统白天的潜热通量占净辐射通量的比例明显高于荒漠生态系统;草地生态系统在5-8月呈现较强的碳汇,而荒漠生态系统表现为弱碳汇.亚洲中部干旱区草地和荒漠生态系统水汽通量和总初级生产力对降水、净辐射通量或光合有效辐射、饱和水汽压差、气温均表现出明显的敏感性

Aripiprazole versus other atypical antipsychotics for schizophrenia

BACKGROUND: In most western industrialised countries, second generation (atypical) antipsychotics are recommended as first line drug treatments for people with schizophrenia. In this review we specifically examine how the efficacy and tolerability of one such agent - aripiprazole - differs from that of other comparable second generation antipsychotics. OBJECTIVES: To evaluate the effects of aripiprazole compared with other atypical antipsychotics for people with schizophrenia and schizophrenia-like psychoses. SEARCH METHODS: We searched the Cochrane Schizophrenia Group Trials Register (November 2011), inspected references of all identified studies for further trials, and contacted relevant pharmaceutical companies, drug approval agencies and authors of trials for additional information. SELECTION CRITERIA: We included all randomised clinical trials (RCTs) comparing aripiprazole (oral) with oral and parenteral forms of amisulpride, clozapine, olanzapine, quetiapine, risperidone, sertindole, ziprasidone or zotepine for people with schizophrenia or schizophrenia-like psychoses. DATA COLLECTION AND ANALYSIS: We extracted data independently. For dichotomous data we calculated risk ratios (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis based on a random-effects model. Where possible, we calculated illustrative comparative risks for primary outcomes. For continuous data, we calculated mean differences (MD), again based on a random-effects model. We assessed risk of bias for each included study. MAIN RESULTS: We included 12 trials involving 6389 patients. Aripiprazole was compared to olanzapine, risperidone and ziprasidone. All trials were sponsored by an interested drug manufacturer. The overall number of participants leaving studies early was 30% to 40%, limiting validity (no differences between groups).When compared with olanzapine no differences were apparent for global state (no clinically important change: n = 703, 1 RCT, RR short-term 1.00 95% CI 0.81 to 1.22; n = 317, 1 RCT, RR medium-term 1.08 95% CI 0.95 to 1.22) but mental state tended to favour olanzapine (n = 1360, 3 RCTs, MD total Positive and Negative Syndrome Scale (PANSS) 4.68 95% CI 2.21 to 7.16). There was no significant difference in extrapyramidal symptoms (n = 529, 2 RCTs, RR 0.99 95% CI 0.62 to 1.59) but fewer in the aripiprazole group had increased cholesterol levels (n = 223, 1 RCT, RR 0.32 95% CI 0.19 to 0.54) or weight gain of 7% or more of total body weight (n = 1095, 3 RCTs, RR 0.39 95% CI 0.28 to 0.54).When compared with risperidone, aripiprazole showed no advantage in terms of global state (n = 384, 2 RCTs, RR no important improvement 1.14 95% CI 0.81 to 1.60) or mental state (n = 372, 2 RCTs, MD total PANSS 1.50 95% CI -2.96 to 5.96).One study compared aripiprazole with ziprasidone (n = 247) and both the groups reported similar change in the global state (n = 247, 1 RCT, MD average change in Clinical Global Impression-Severity (CGI-S) score -0.03 95% CI -0.28 to 0.22) and mental state (n = 247, 1 RCT, MD change PANSS -3.00 95% CI -7.29 to 1.29).When compared with any one of several new generation antipsychotic drugs the aripiprazole group showed improvement in global state in energy (n = 523, 1 RCT, RR 0.69 95% CI 0.56 to 0.84), mood (n = 523, 1 RCT, RR 0.77 95% CI 0.65 to 0.92), negative symptoms (n = 523, 1 RCT, RR 0.82 95% CI 0.68 to 0.99), somnolence (n = 523, 1 RCT, RR 0.80 95% CI 0.69 to 0.93) and weight gain (n = 523, 1 RCT, RR 0.84 95% CI 0.76 to 0.94). Significantly more people given aripiprazole reported symptoms of nausea (n = 2881, 3 RCTs, RR 3.13 95% CI 2.12 to 4.61) but weight gain (7% or more of total body weight) was less common in people allocated aripiprazole (n = 330, 1 RCT, RR 0.35 95% CI 0.19 to 0.64). Aripiprazole may have value in aggression but data are limited. This will be the focus of another review. AUTHORS' CONCLUSIONS: Information on all comparisons are of limited quality, are incomplete and problematic to apply clinically. Aripiprazole is an antipsychotic drug with a variant but not absent adverse effect profile. Long-term data are sparse and there is considerable scope for another update of this review as new data emerges from the many Chinese studies as well as from ongoing larger, independent pragmatic trials