群落排表分类的两种数学方法

本文描述两种执行群落排表分类的数学方法:X²分类法和信息熵分类法,并以德国西北部草地数据为例进行了应用和分析。结果表明这两个方法都是有效的群落排表分类方法,它们所排的群落表可直接地反映群落类型和种类组成之间的关系,体现了Braun-Blanquet传统排表法的特点。     

昆虫迁飞随气流散布若干问题的商榷

昆虫通过飞翔从一个生境迁移到另一个新的生境,是普遍存在的自然现象,而随气流远距离季节性迁飞是在特定环境条件下产生的,是昆虫与环境在进化过程中的统一。对于迁飞的个体,“从A迁飞到B,并在B获得生境”是随机事件,但对于迁飞的群体则存在统计规律。迁飞昆虫以被动的随气流散布方式,获得对环境的主动适应。     

黎族、汉族通婚后裔体征的遗传变异

从“t”值测验表明,黎汉通婚后裔在形态特征上有些变化。与黎族相比,蒙古褶出现率显著增多,上眼睑皱褶发育明显减弱;与汉族相比,波形鼻梁明显增加,上翘型鼻尖和鼻基底显著增多,水平型明显减少。从测量性特征的比较表明,通婚后裔在体征上较多地显示汉族的性状,比黎族更接近于汉族。     

枯草杆菌二联活菌对儿童巨细胞病毒性肝炎患儿肠道菌群及预后的影响

目的 探究枯草杆菌二联活菌对儿童巨细胞病毒(CMV)性肝炎患儿肠道菌群的调节作用及其对预后的影响.方法 选择2016年5月到2019年5月我院收治的81例重症巨细胞病毒性肝炎患儿为研究对象,按照随机数字表法分为联合组(n=41)和对照组(n=40).对照组患儿采用常规治疗方法,联合组患儿在对照组基础上联合枯草杆菌二联活...     

有机肥替代化学氮肥对橡胶幼苗生长和土壤环境的影响

研究有机肥替代化学氮肥对橡胶幼苗生长和土壤环境的影响对橡胶的培育移植和土壤环境的改善具有重要意义.本研究以热研'7-33-97'品系橡胶幼苗为材料,以等氮(每株幼苗4.63 g全氮)替换的方式设置不施肥(CK)、单施化肥(N)、有机肥替代50％化肥(M+N)、有机肥替代100％化肥(M)4个施肥处理,分析了有机肥替代化...     

神经刺激仪经肌间沟定位臂丛神经分支行臂丛麻醉效果分析

目的：比较神经刺激仪经肌间沟定位臂丛神经分支行肌间沟臂丛神经阻滞麻醉的效果及安全性。方法：选择拟行肌间沟臂丛神经阻滞的上肢手术的患者80例,ASAI或II级,随机均分为A组和B组,每组40例患者。两组均给予1％的利多卡因＋0．375％耐乐品20mL。记录完成操作所需时间、感觉神经阻滞起效时间、感觉神经阻滞完善时间、运动神经阻滞起效时间、运动神经阻滞完善时间;评价手术区域麻醉效果（优、良、差、失败）;观察并记录并发症。结果：A组完成操作所需时间（5．01±1．40）min,明显长于B组（2．83＋O．87）min（P〈0．01）。A组感觉阻滞起效时间（4．48±1．36）min,明显短于B组（7．0±2．06）min（P〈0．01）;A组运动阻滞起效时间（4．88＋±1．18）min,明显短于B组（7．0±1．67）min（P〈0．01）。A组感觉阻滞完善时间（11．73±3．62）短于B组（13．33±3．02）min（P=0．033）。A组运动阻滞完善时间（11．18±2．73）短于B组（12．41±2．48）min（P=0．038）;麻醉效果优等率A组为87．5％,B组为67．5％,差异有统计学意义x^2=4．588,P=0．032;优良率A组为97．5％,B组为90．0％,差异无统计学意义x2=1．920,P=0．166;A组、B组均未出现严重麻醉并发症。结论：A组行肌间沟臂丛神经阻滞比B组阻滞操作时间长,但神经阻滞麻醉效果好,神经阻滞完善率高。     

Molecular determinants for the action of general anesthetics at recombinant α2β3γ2γ-aminobutyric acidA receptors

General anesthetics modulate the activity of ligand-gated ion channels including the GABA(A) receptor. Mutational studies mainly on the benzodiazepine-insensitive alpha(2)beta(1(M286W)) and alpha(6)beta(3(N289M))gamma(2) GABA(A) receptors revealed that a serine in transmembrane domain 2 and a methionine in transmembrane domain 3 are essential for the action of most general anesthetics. We investigated whether these residues would similarly be relevant for their action at the benzodiazepine-sensitive GABA receptor subtype, alpha(2)beta(3)gamma(2). We found that not only the N265M but also the M286W mutation nearly abolished the modulatory effect of etomidate. However, the anti-convulsant loreclezole, a structural homologue of etomidate, was inactive on the N265M mutant, but displayed normal modulatory activity on the M286W mutant. Both mutations did not affect the modulatory action of the neurosteroid alphaxalone. The direct action of alphaxalone, however, was dramatically increased in the M286W mutant to about twice the maximal GABA current but not significantly affected in the N265M mutant. These data demonstrate that the structural requirements for modulatory and direct actions of various general anesthetics are distinct. The molecular switches induced by these mutations can be exploited to identify the molecular determinants for the action of general anesthetics.     

Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes

The procedures described in this article involve the synthesis and isolation of hypervalent iodonium alkynyl triflates (HIATs) and their subsequent reactions with azides to form cyanocarbene intermediates. The synthesis of hypervalent iodonium alkynyl triflates can be facile, but difficulties stem from their isolation and reactivity. In particular, the necessity to use filtration under inert atmosphere at -45 °C for some HIATs requires special care and equipment. Once isolated, the compounds can be stored and used in reactions with azides to form cyanocarbene intermediates. The evidence for cyanocarbene generation is shown by visible extrusion of dinitrogen as well as the characterization of products that occur from O-H insertion, sulfoxide complexation, and cyclopropanation. A side reaction of the cyanocarbene formation is the generation of a vinylidene-carbene and the conditions to control this process are discussed. There is also potential to form a hypervalent iodonium alkenyl triflate and the means of isolation and control of its generation are provided. The O-H insertion reaction involves using a HIAT, sodium azide or tetrabutylammonium azide, and methanol as solvent/substrate. The sulfoxide complexation reaction uses a HIAT, sodium azide or tetrabutylammonium azide, and dimethyl sulfoxide as solvent. The cyclopropanations can be performed with or without the use of solvent. The azide source must be tetrabutylammonium azide and the substrate shown is styrene.     

The multi-PDZ domain protein-1 (MUPP-1) expression regulates cellular levels of the PALS-1/PATJ polarity complex

MUPP-1 (multi-PDZ domain protein-1) and PATJ (PALS-1-associated tight junction protein) proteins are closely related scaffold proteins and bind to many common interactors including PALS-1 (protein associated with Lin seven) a member of the Crumbs complex. Our goal is to understand how MUPP-1 and PATJ and their interaction with PALS-1 are regulated in the same cells. We have shown that in MCF10A cells there are at least two different and co-existing complexes, PALS-1/MUPP-1 and PALS-1/PATJ. Surprisingly, MUPP-1 levels inversely correlated with PATJ protein levels by acting on the stabilization of the PATJ/PALS-1 complex. Upon MUPP-1 depletion, the increased amounts of PATJ are in part localized at the migrating front of MCF10A cells and are able to recruit more PAR3 (partition defective 3). All together these data indicate that a precise balance between MUPP-1 and PATJ is achieved in epithelial cells by regulating their association with PALS-1.