基于多层次模糊综合评判法的小区域森林火灾风险分析

本文以徂徕山林场森林资源为研究对象,在对影响森林火灾风险诸要素进行充分分析的基础上,确立了基于小班水平的小区域森林火灾风险综合评价指标体系,并采用多层次模糊综合评判法对森林火灾风险进行分析评价,建立了徂徕山林场基于小班水平的森林火灾风险评价系统,从而为管理者实施森林火灾风险管理提供依据.随着森林火灾风险影响因子的不断变化,管理者可根据最新调查数据更新指标体系属性值,对森林火灾风险进行新的评价,从而调整、改进风险管理措施。最终实现森林火灾风险的适应性管理.     

大兴安岭北坡火烧迹地自然与人工干预下的植被恢复模式初探

针对大兴安岭北坡林区森林植被在不同火烧强度、火烧时间的火烧迹地上的恢复状况进行了调查研究。结果表明,轻度火烧区的植被自然更新恢复良好;中度火烧区的森林植被依靠人工促进更新要比自然更新更早达到预期目标;重度火烧区的森林植被如果完全依靠自然更新,恢复到预期目标会非常缓慢,而通过人工更新则可跨越几个演替阶段,较快接近本地的顶极群落。     

福建三明不同更新方式的米槠林物种多样性研究

本文从α多样性尺度总结三种不同更新方式的米槠林群落的物种多样性状况。结果表明,不同更新方式的米槠林群落中,物种丰富度、多样性指数和均匀度表现为天然更新> 人促更新> 人工造林。天然更新和人促更新米槠林是在皆伐迹上未经炼山发育起来的群落,而人工造林米槠林是从火烧迹地上发育的。天然更新米槠林处于演替的中级阶段,未达到顶级群落;而人促更新和人工造林米槠林则处于衰退阶段。     

不同更新方式对林地植被生长及土壤性状的影响

本文研究天然次生林采伐迹地的三种更新方式对林地植被及土壤性状的影响。结果表明,炼山人工造林对林地植被和土壤有一定的破坏作用,是影响林木生长、导致物种丧失、引起林地水土流失和地力衰退的重要原因。不同林分物种丰富度为:天然更新 >人促更新 >炼山人工造林;林下植被生物量为:人促更新 >天然更新 >炼山人工造林。不炼山的天然更新和人促更新,有利于物种多样性保护、植被生长、林地土壤理化性状改善和土壤肥力提高,并具有更高的经济效益。     

提高人工造林成效的对策研究

随着现代工业化进程的加快,我国的经济得到了更快的发展,虽然经济水平得到了很大程度的提高,但是我国的生态环境却遭到了严重的破坏。我国是一个拥有丰富森林资源的大国,由于砍伐与开发的不合理,森林资源遭受到了严重的破坏。为了能够有效地保护好森林资源,人工造林更新工作十分必要。然而我国的人工造林更新工作存在着一些问题,直接影响了我国的生态建设。本文将对提高人工造林更新成效的相应对策进行简要的分析探讨。     

人工造林更新工作的对策研究

随着生态型社会理念的提出以及退耕还林政策的持续深入,我国人工造林工程越来越受到国家和社会的重视。虽然近年来我国在人工造林更新工作上的成绩斐然,但也暴露出了一系列问题,在一定程度上干扰了造林工程的正常进行。本文将针对人工造林更新中的措施和需要注意的一些相关事项进行简要的分析。     

经营方式对亚热带森林土壤可溶性有机碳含量和光谱学特征的影响

人工促进天然更新与人工造林经营方式中采伐剩余物管理等人工措施的差异,可能改变土壤可溶性有机碳(DOC)的含量和结构,影响森林碳循环。本研究利用天然次生林(对照)采伐迹地上通过人工促进天然更新林(简称人促更新林)和人工造林两种营林方式,研究经营方式对中亚热带森林土壤溶液可溶性有机碳含量和光谱特征的影响。结果表明:天然次生林转换为人促更新林和人工林后,0～10 cm土层土壤DOC含量显著降低,分别下降21%和50%;0～10 cm和10～20 cm土层土壤DOC/SOC(土壤有机碳)值也显著降低,分别达到27%和43%。在0～10 cm土层中,人促更新林土壤DOC芳香化指数和腐殖化指数显著高于人工林,人促更新林土壤DOC在3700～3000、1650～1620、1160～1000、690～530 cm^-1范围内的红外吸收比例较人工林高,表明人促更新林土壤DOC的羧酸类物质、芳香化物质丰富;人促更新林和人工林土壤DOC的荧光指数均为1.4～1.9,且人促更新林自生源指数显著高于人工林,说明人工林土壤DOC类蛋白组分贡献大,容易被微生物分解利用。人促更新林与人工林土壤DOC含量和结构的差异可能是人促更新林的土壤碳库比人工林更高的原因之一。     

川南天然常绿阔叶林人工更新后土壤团粒结构的分形特征

运用分形模型研究了川南天然常绿阔叶林及其人工更新成檫木(Sassafras tzumu)林、柳杉(Cryptomeria fortunei)林和水杉(Metasequoia glyptostroboides)林后土壤团粒结构,探讨了分形维数与林地土壤水源涵养功能、肥力特征和微生物数量之间的关系。结果表明:天然常绿阔叶林人工更新后土壤团粒结构的分形维数和结构体破坏率增大、土壤物理性质变差、养分含量和微生物数量降低,3种人工林中,檫木林较好、水杉林次之、柳杉林最差;土壤团聚体、水稳性团聚体和水稳性大团聚体含量越高分形维数越小;在湿筛条件下,土壤结构体破坏率随分形维数的降低而减小;土壤团粒结构的分形维数与土壤物理性质、养分含量和微生物数量之间存在显著的回归关系。这表明天然常绿阔叶林人工更新后由于不同林分对林地土壤组成结构的维护效果不同,导致更新后林地土壤物理、化学和生物性质变化,林地土壤团粒结构的变化,进而影响其分形维数的大小。因此,分形维数可作为天然常绿阔叶林及其人工更新后林地土壤水源涵养功能、肥力特征和微生物活动情况的一项综合性定量化评价指标。同时,为保护天然常绿阔叶林、选择适宜的更新树种和天然常绿阔叶林人工更新后林地土壤的科学管理提供依据,也为退耕还林中树种的选择提供参考。     

不同采伐更新模式对米槠群落植物物种β多样性的影响

运用β多样性测度公式,以福建武平建立的永久样地12年的数据,探讨不同采伐模式（择伐更新、天然更新和人工更新）对米槠群落（Castanopsis carlesii community）的影响。结果表明：择伐更新和天然更新不同更新期的顶极种米槠均为优势种、高竞争种;择伐更新的Jaccard指数（CJ）、Sorenson指数（CS）、Bray—Curtis指数（CN）和Morisita—Hom指数（CMN）都在80％以上,属于轻度干扰;天然更新在64％～88％之间,属于中度干扰;而人工更新除皆伐前优势种为米槠外,人工种植的杉木为优势种,不同更新阶段之间的β多样性指数（CJ、CS、CN、CMN）在15％－49％之间,属于强度干扰,目前不能恢复到米槠群落。择伐更新和天然更新在更新过程中均恢复到米槠群落,不同更新期间β多样性的相似性指数在50％以上,物种多样性能保持或呈上升趋势,表明这二种经营模式对群落的干扰较合理。     

亚热带森林林分更新对地表径流4种盐基离子浓度的影响

地表径流不仅是水循环的重要组成部分,也是森林物质迁移的重要途径,其动态过程可能受林分更新的调控,目前仍缺乏必要的关注.通过对福建省三明市米槠(Castanpsis carlesii)次生林、杉木(Cunning-hamia lanceolata)人工林、杉木人工幼林和米槠人工幼林近5年的定位观测,探讨林分更新对地表径流...     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.