林分垂直结构与静态持水能力的关系

从林分垂直结构的角度入手,对黑龙江省东部山区的6种天然次生乔木林的乔木层郁闭度、蓄积量、灌木层和草本层的生物量、枯落物层和土壤层的持水能力进行调查、测定和分析。结果表明:郁闭度适当时,林内植被生长状况越好,其林分持水能力就越大,枯落物最大持水量变化幅度在46.59～86.28t/hm2,有效持水量在24.87～55.29t/hm2;土壤层的最大持水量变化幅度为3108.1～4061.8t/hm2,有效持水量变化幅度为2893.7～3736.2t/hm2。灌木层和草本层的生物量越大,持水能力大的种类越多,对枯落物的储量的增加作用就大,使枯落物的持水能力也有所增加。不同林分结构不同郁闭度影响了林下植被的种类及数量,从而影响林下植被层的持水能力。     

不同地理分布区的紫椴形态结构

对不同地理分布区(辽宁凤凰山、吉林长白山、黑龙江宁安、勃利、带岭、新青林业局、胜山自然保护区、内蒙古大杨树林业局)紫椴的宏观形态结构进行了比较分析,结果表明:无论是不同纬度还是不同海拔,紫椴的形态结构数值变化均具有一定的规律;除有花数目与纬度和海拔、叶片宽与海拔不相关外,紫椴的其它形态结构与纬度和海拔之间具有显著的相关性,且多为负相关;紫椴的枝叶、苞片和花序形态结构在纬度和海拔梯度上的变化是不连续的,与遗传距离不相关,说明其形态结构的变化主要是由于环境压力造成的;果和种子的形态结构完全按纬度和海拔距离而聚类,在纬度和海拔梯度上是连续的,说明其主要受遗传因素所影响。     

大豆脂氧酶的热失活动力学与其二级结构的圆二色谱表现

应用大豆脂氧酶的变温圆二色谱图研究了大豆脂氧酶(LOX)的热失活与二级结构变化过程.结果表明:在50一65℃条件下,10 min内,LOX的酶活随热处理时间延长而下降,其热失活过程遵循一级动力学,活化能Ea值为217 kJ.mol-1.在相同的热处理条件下,LOX中二级结构a-螺旋和β-折叠的相对含量均在20%左右浮动...     

绿肥对咖啡园杂草多样性及功能群的影响

为揭示绿肥对咖啡园杂草多样性及功能群的影响,调查了云南省保山市常规种植咖啡园（CK）、种植绿肥田菁咖啡园（SC）、种植绿肥硬皮豆咖啡园（MU）的杂草群落,探讨种植绿肥对咖啡园杂草群落的生态位、多样性、群落结构相似性及功能群的影响。结果表明：CK有杂草12科21种,SC有杂草10科16种,MU有杂草7科10种。3种类型咖啡园杂草生态位宽度大于0.600的杂草有10种,其中,CK有6种,SC有2种,MU有3种。种植绿肥的咖啡园杂草的物种丰富度、个体数、ACE估计值、Fisher α指数、Shannon-Wiene指数及生物量均低于常规种植咖啡园（CK）,其中,杂草物种丰富度、ACE估计值和鲜重具有显著性差异。常规种植咖啡园与种植绿肥咖啡园杂草群落结构不相似。3种类型咖啡园杂草单子叶一年生或越年生植物功能群占据最大优势,但种植绿肥咖啡园的占比更高。种植绿肥改变了咖啡园杂草群落的生态位、群落结构及功能群,降低了咖啡园杂草群落多样性,对咖啡园杂草群落产生了影响。     

Natural Marine Products: Anti-Colorectal Cancer In Vitro and In Vivo

Colorectal cancer, a malignant tumor with high mortality, has a poor prognosis due to drug resistance and toxicity in clinical surgery and chemotherapy. Thus, finding safer and more efficient drugs for clinical trials is vital and urgent. Natural marine compounds, with rich resources and original chemical structures, are applied widely in anticancer treatments. We provide a systematic overview of recently reported marine compounds such as alkaloids, peptides, terpenoids, polysaccharides, and carotenoids from in vitro, in vivo, and clinical studies. The in vitro studies summarized the marine origins and pharmacological mechanisms, including anti-proliferation, anti-angiogenesis, anti-migration, anti-invasion, the acceleration of cycle arrest, and the promotion of tumor apoptosis, of various compounds. The in vivo studies outlined the antitumor effects of marine compounds on colorectal cancer model mice and evaluated their efficacy in terms of tumor inhibition, hepatotoxicity, and nephrotoxicity. The clinical studies summarized the major chemical classifications and targets of action of the clinical drugs that have entered clinical approval and completed approval for marine anticancer. In summary, we present the current situation regarding the application of natural anti-colorectal cancer marine compounds and prospects for their clinical application.     

酪蛋白和胞外多糖作用机理研究进展

在酸乳的发酵过程中,牛乳中的酪蛋白在乳酸菌形成的乳酸作用下,相互凝集构成立体网状结构.发酵过程中产生的乳酸菌胞外多糖会对酪蛋白立体网状结构的形成产生一定的影响.乳酸菌胞外多糖(EPS)和酪蛋白之间的作用直接影响着酸乳制品的风味、粘度、质构和持水力等特性.     

2018年春季和夏季莱州湾营养盐结构及限制特征

根据2018年5、8月莱州湾的生态调查资料,采用营养盐限制法则及潜在性富营养化评价模式等方法,对莱州湾无机氮(DIN)、活性磷酸盐(PO34–-P)和硅酸盐(SiO23–-Si)的平面分布、结构及限制特征进行了分析。结果显示,2018年5、8月莱州湾的DIN浓度范围为1.64~106.36 μmol/L,平均值为24.18 μmol/L,5月明显高于8月;PO34–-P浓度范围为0~2.010 μmol/L,平均值为0.182 μmol/L,8月明显高于5月;SiO23–-Si浓度变化范围为0.97~78.93 μmol/L,平均值为18.30 μmol/L,8月明显高于5月。DIN、PO34–-P、N/P高值区主要位于莱州湾西部的小清河口和黄河口附近海域;SiO23–-Si、Si/N、Si/P高值区主要位于湾底部、龙口–莱州近岸海域。对营养盐结构的分析表明,莱州湾存在明显的磷限制和枯水期的硅限制,陆源输入是莱州湾营养盐的主要来源。营养盐结构限制平面分布表明,春季莱州-招远养殖区和夏季东营-潍坊养殖区易引发赤潮,夏季莱州–招远养殖区初级生产力受到一定限制,对养殖业造成一定的影响。     

Biodeterioration of historic timber structures: A comparative analysis

Abstract

Service life of timber structures in the north of Europe is decreased mainly by biological agents. Increasing risk of biological infestation due to global warming is widely discussed nowadays. Historic timber structures which have been monitored for decades provide us with valuable information on this subject. An investigation of the structures in the Kizhi museum, located in the northwest of Russia was carried out in the 1970s and in 2011–2012. Identification of wood-decay fungi that destroy constructive elements of seventeenth- and nineteenth-century monuments showed that the most frequent damages are caused by brown rot fungi. At the same time, imperfect fungi and ascomycetes which cause soft rot began to play a significant role in damaging historic timber structures. Borers (Hadrobregmus pertinax L. and H. confusus Kraaz) play the leading part in reducing the service life of seventeenth- and nineteenth-century heritage objects. During a forest inventory, some wood-borers not registered previously as timber structure pests in the Kizhi archipelago region (Republic of Karelia, Russia) were found. Twenty-seven species of foliose and fruticose lichens and ten species of crustose lichens were found on the monuments' structural elements.     

Chemistry of immunomodulators

A large number of synthetic derivatives, inorganic compounds or naturally occurring substances are able to depress, regulate or enhance the immune response. Immunomodulators, among which some are chemically well defined and others are complex preparations, exhibit a great variety of chemical structures which are briefly reviewed, without details on their immunopharmacological properties. These molecules allow access to a new type of therapy which aims at acting on the host defense mechanisms.     

泄水建筑物下游矩形收缩断面水深直接求解法

关于矩形收缩断面水深，试算法精度虽可以得到控制，但计算费时，图解法由于制图及查图的误差，精度又欠佳。为此，笔者通过大量的分析验证，提出了一种精度高，计算简捷方便的直接求解法。