丙烯腈-水-氟化钾及丙烯腈-水-碳酸钾体系的液-液相平衡

采用氟化钾或碳酸钾分离丙烯腈-水时,可产生水富集相(水相)和丙烯腈富集相(丙烯腈相).测定了丙烯腈-水-氟化钾、丙烯腈-水-碳酸钾体系在40℃时的液-液相平衡数据,用Pitzer理论和NRTL方程对液-液相平衡数据进行了理论计算.结果表明:产生的丙烯腈相中含有可以忽略的盐,水相中含有可以忽略的丙烯腈,因此用氟化钾或碳酸钾可以有效地分离丙烯腈-水体系;丙烯腈富集相的实验值与计算值接近,对丙烯腈-水-氟化钾体系绝对平均偏差为0.20%,对丙烯腈-水-碳酸钾体系绝对平均偏差为0.22%.     

高浓度丙烯腈废水的辐照处理

为考察优先污染物丙烯腈在γ辐照下的去除情况,选取了高浓度的丙烯腈废水作为研究对象,利用60Co作为γ射线源进行辐照分解,并利用吡啶比色法测定水中丙烯腈的含量,研究了丙烯腈的辐照降解。结果表明:辐照剂量为15kGy时,丙烯腈去除率随初始浓度的增大而增大;初始质量浓度为4g/L的丙烯腈溶液,随着辐照剂量的增大,丙烯腈的去除率先增加后减小,10 kGy时的去除效果最佳,去除率达到90%以上;在中性条件下的去除效果要好于偏酸或偏碱性条件;添加FeCl3对丙烯腈去除率的影响很小。     

丙烯腈装置系统高效清理方法浅析

大庆石化公司化工二厂丙烯腈装置自投产以来,一直探索长周期生产的思路和方法,以使装置效益最大化,针对国内丙烯腈装置普遍存在运行周期短的问题,分析了影响装置长周期运行的关键因素,提出丙烯腈系统高效清理的具体措施。     

聚丙烯腈的研究——丙烯腈在浓无机盐溶液中的光聚合与共聚合

1.丙烯腈,丙烯腈—氯代醋酸乙烯,丙烯腈—丙烯骏甲酯,丙烯腈—丙烯酸乙酷,丙烯腈—丙烯酸,丙烯腈—丙烯酰胺和丙烯腈—乙烯吡啶在濃无机盐溶液中的光聚合反应可以用效率好的有机光敏剂引发聚合,在5小时左右除与氯代醋酸乙烯共聚的转化率较低外其余的都可达到或超过90%。 2.光敏剂对光聚合反应有较大的影响,我们找到了性能优良的有机光敏剂。 3.用此法进行光聚合反应所得之母液,不分层,为透明的液体,壁上稍有小汽泡,这些母液可以用来直接抽丝,抽出的丝性质优良,共聚物还容易染色。     

CTA—6催化剂最佳使用条件的确定

本从理论上论述了新型国产丙烯腈催化剂CTA－6的使用条件对丙烯腈收率、催化剂使用寿命及产品质量的影响，在实践的基础上提出了该催化剂的最佳使用条件，对丙烯腈催化剂技术国产化具有重要意义。     

丙烯腈作业对男工生殖结局的影响

丙烯腈作业对男工生殖结局的影响李芝兰（兰州医学院劳动卫生教研室７３００００）丙烯腈是有机合成工业的主要单体及化工中间体，但关于丙烯腈对人类生殖损伤的报道甚少。为此，笔者于１９９１年３～４月进行了丙烯腈作业对男工生殖结局影响的回顾性调查。旨在为防护和控...     

丙烯酰胺在浓硫氰酸钠水溶液中对聚丙烯腈及其共聚物的紫外辐射接枝聚合的研究

本文报告丙烯酰胺在浓硫氰酸钠水溶液中对于丙烯腈均聚物及丙烯腈与α-溴代丙烯腈共聚物上的紫外光辐照接枝聚合,进行了丙烯酰胺单体的浓度,聚合物浓度,共聚物组成及反应时间等对接枝效率影响的研究。当聚合物的浓度在2％以下时,接枝效率随丙烯酰胺浓度及反应时间的增加而增加,当聚合物浓度继续增加到6％时接枝效率反而下降。对于丙烯腈与α-溴代丙烯腈的共聚物,其接枝效率在低溴含量(1—2％)共聚物下较高。     

H—SPAN树脂的制备及其性能研究

本文报导了由淀粉和丙烯腈接枝共聚制备淀粉接枝丙烯腈高吸水树脂H—SPAN的一种方法,并对其性能进行了初步研究.     

o-,m-,p-二甲苯+丙烯腈体系的汽液平衡

在101．325kPa下用Ellis汽液平衡釜测定了丙烯腈 o-二甲苯、丙烯腈 m-二甲苯、丙烯腈 p-二甲苯3个二元体系的汽液平衡数据,并进行了恒压下热力学一致性的检验,用Wilson方程关联了实验数据,拟合精度令人满意．     

分子间相互作用的量子化学研究——Ⅱ.芳烃超分子

根据研究报告Ⅰ所提出的理论公式和自编程序 CNDO/LP,对丙烯腈——苯、丙烯腈——甲苯、丙烯腈——苯乙烯、苯——苯酚及莽——苯甲醛五个超分子体系,进行了分子间相互作用的研究,对这些新体系的络合机制作了讨论.     

辣椒自发和诱发2n花粉的形成及细胞遗传学机理

自然条件下，辣椒（Ｃａｐｓｉｃｕｍ ｆｒｕｔｅｓｃｅｎｓＬ．）小孢子形成过程中存在１％ 以下的二分体和三分体。人工诱导可使二分体、三分体的比率分别提高到４５％ 和３．２９％ ，其中２１．５２％的二分体和多数三分体由双核小孢子构成，但是，成熟花粉中仅５．６５％ 为２ ｎ 花粉。细胞遗传学研究结果表明：辣椒自发２ ｎ 花粉主要来源于减数分裂过程中的细胞质分裂异常和少部分第１ 次分裂重组，而人工诱发的２ ｎ 花粉则主要来源于由不联会造成的第１ 次分裂重组，也有部分细胞质异常分裂。     

任务型活动中小组人数对协商互动的影响

研究采取了我国任务型语言教学中常用的两人、三人、四人小组的分组方法,考察了这三种小组人数结构下学习者的意义协商数量和互动参与度。结果表明,四人小组中的意义协商数量显著多于两人和三人小组;在互动参与度上,小组人数不影响小组的总体互动参与度,但是两人小组中组员的个体参与度较为均衡,三人和四人小组中只有两位组员在互动中占主导,其他组员参与较少,这可能主要是由多人小组互动中的交际压力所致。     

用微机估算三元共聚物的结构特性

介绍一种计算机通用程序，应用此程序可以计算出在低转化率下制备的三元共聚物的结构特性，包括共聚物的组成，二元组、三元组、四元组和五元组的分布，单体序列的重量和数量分布，单体为中心的三元组和五元组的分数。此程序可应用于末端基团效应的三元共聚体系中。此外还讨论了程序编制过程中所用的计算方法。     

The Duchenne muscular dystrophy gene product is localized in sarcolemma of human skeletal muscle

Duchenne muscular dystrophy (DMD) and its milder form, Becker muscular dystrophy (BMD), are allelic X-linked muscle disorders in man. The gene responsible for the disease has been cloned from knowledge of its map location at band Xp21 on the short arm of the X chromosome. The product of the DMD gene, a protein of relative molecular mass 400,000 (Mr 400K) recently named dystrophin, has been reported to co-purify with triads of mouse and rabbit skeletal muscle when assayed using polyclonal antibodies raised against fusion proteins encoded by regions of mouse DMD complementary DNA. Here we show that antibodies directed against synthetic peptides and fusion proteins derived from the N-terminal region of human DMD cDNA strongly react with an antigen present in skeletal muscle sarcolemma on cryostat sections of normal human muscle biopsies. This immunoreactivity is reduced or absent in muscle fibres from DMD patients but appears normal in muscle fibres from patients with other myopathic diseases. The same antibodies specifically react with a 400K protein in sodium dodecyl sulphate (SDS) extracts of normal human muscle subjected to Western blot analysis. We conclude that the product of the DMD gene is associated with the sarcolemma rather than with the triads and speculate that it strengthens the sarcolemma by anchoring elements of the internal cytoskeleton to the surface membrane.     

低不饱和度聚醚多元醇的结构与表征

采用红外、核磁、质谱、GPC等实验方法分别对低不饱度聚醚多元醇环氧丙烷(PO)/环氧乙烷(EO)共聚醚、环氧丙烷(PO)均聚醚进行了链结构的组成及序列结构分析.由红外光谱中1 374和1 010 cm-1的特征吸收峰确定了链中的氧丙基团.MALDI-TOF-MS确定了样品的组成和分子质量,且与GPC测试的结果进行了对比;1H NMR计算出了样品的起始剂甘油在单体的质量百分数为4.0%,共聚醚链中EO的质量百分数为8%.利用13C NMR测试结果推测出了样品链段中的两单元或三单元的序列结构.     

Restoration of dysgenic muscle contraction and calcium channel function by co-culture with normal spinal cord neurons

Muscular dysgenesis (mdg) is a spontaneous recessive lethal mutation in the mouse. The disease is characterized by a total lack of excitation-contraction coupling in embryonic skeletal muscle. This developmental abnormality is associated with a drastic deficiency in the expression of voltage-sensitive Ca2+ channels in skeletal muscle without alteration of the properties of voltage-sensitive Na+ channels or of voltage-sensitive Ca2+ channels in cardiac and neuronal cells. Membrane couplings between sarcoplasmic reticulum and the transverse tubules, known as triads, were also found to be drastically altered in embryonic muscle of the homozygous mutant (mdg/mdg). Triads in the mdg/mdg muscle were less numerous, disorganized and lacked spaced densities. This paper shows that co-culture of mdg/mdg myotubes with normal spinal cord neurons re-establishes Ca2+ channel activity, contraction and normal triad organization. The decrease thus cannot be due to a mutation of the Ca2+ channel as previously suggested. Normal nerve cells may supply an essential factor to mutant muscle cells.     

A model for interfacial activation in lipases from the structure of a fungal lipase-inhibitor complex

Lipases are hydrolytic enzymes which break down triacylglycerides into free fatty acids and glycerols. They have been classified as serine hydrolases owing to their inhibition by diethyl p-nitrophenyl phosphate. Lipase activity is greatly increased at the lipid-water interface, a phenomenon known as interfacial activation. X-ray analysis has revealed the atomic structures of two triacylglycerol lipases, unrelated in sequence: the human pancreatic lipase (hPL)4, and an enzyme isolated from the fungus Rhizomucor (formerly Mucor) miehei (RmL). In both enzymes the active centres contain structurally analogous Asp-His-Ser triads (characteristic of serine proteinases), which are buried completely beneath a short helical segment, or 'lid'. Here we present the crystal structure (at 3 A resolution) of a complex of R. miehei lipase with n-hexylphosphonate ethyl ester in which the enzyme's active site is exposed by the movement of the helical lid. This movement also increases the nonpolarity of the surface surrounding the catalytic site. We propose that the structure of the enzyme in this complex is equivalent to the activated state generated by the oil-water interface.     

面向抒情歌曲旋律的钢琴自动伴奏算法

目前钢琴自动伴奏中存在着一定的不和谐问题,其中一个重要原因是由于和弦处理的固定性往往不能满足旋律的不确定性要求.为此,提出一种面向拍号固定的抒情歌曲旋律的自适应伴奏算法.首先,根据拍号对旋律进行小节分割和乐句整合,在传统三度关系的三和弦基础上定义更泛化的三元和弦,自适应获取三元和弦的内部音程关系;然后,自适应计算旋律音对和弦的贡献分值,以获取小节中所有可能的三元和弦;自动选取和弦个数,将选出的和弦与知识库进行匹配,将匹配成功的和弦添加合适的伴奏音型,最终生成伴奏.实验结果表明,人们不容易将该算法生成的伴奏与人工的伴奏进行区分.     

Protein functional-group 3D motif and its applications

Representing and recognizing protein active sites sequence motif (1D motif) and structural motif (3D motif) is an important topic for predicting and designing protein function. Prevalent methods for extracting and searching 3D motif always consider residue as the minimal unit, which have limited sensitivity. Here we present a new spatial representation of protein active sites, called "functional-group 3D motif ", based on the fact that the functional groups inside a residue contribute mostly to its function. Relevant algorithm and computer program are developed, which could be widely used in the function prediction and the study of structural-function relationship of proteins. As a test, we defined a functional-group 3D motif of the catalytic triad and oxyanion hole with the structure of porcine trypsin (PDB code: 1mct) as the template. With our motif-searching program, we successfully found similar sub-structures in trypsins, subtilisins and a/b hydrolases, which show distinct folds but share similar catalytic mechanism. Moreover, this motif can be used to elucidate the structural basis of other proteins with variant catalytic triads by comparing it to those proteins. Finally, we scanned this motif against a non-redundant protein structure database to find its matches, and the results demonstrated the potential application of functional group 3D motif in function prediction. Above all, compared with the other 3D-motif representations on residues, the functional group 3D motif achieves better representation of protein active region, which is more sensitive for protein function prediction.     

魔芋在不同土壤环境条件的含硒量

通过分析从湖北恩施采集的野外魔芋样品和2种土壤加硒盆栽实验的魔芋样品的含硒量,研究魔芋在不同土壤环境中的含硒量、富硒特征及其影响因素.结果表明,随采样点不同,野外魔芋样品的含硒量不同,魔芋球茎和茎叶的最高含硒量为5.58和13.04μg g-1,并与土壤含硒量呈极显著的线性相关,茎叶含硒量高于球茎.盆栽实验条件下,魔芋含硒量与土壤施硒量呈极显著的线性相关,魔芋球茎和茎叶最高含硒量在潮土中为55.6和76.8μg g-1,在红壤中为14.5和21.4μg g-1,茎叶的含硒量显著高于球茎,潮土魔芋的含硒显著高于红壤.魔芋对土壤硒的生物富集系数均表现为茎叶高于球茎,潮土魔芋的生物富集系数高于红壤,土壤施硒的富集系数高于天然含硒土.总之,魔芋能吸收利用天然富硒土和施人到土壤中的硒,土壤类型和土壤硒水平是影响魔芋含硒的关键因素,土壤施硒的有效性高于天然含硒土,潮土施硒的有效性高于红壤.