不同质地土壤的水热状况及其对冬小麦产量形成的影响

对豫东平原３种质地土壤的水热状况和冬小麦籽粒生长特征进行了研究．结果表明,冬小麦籽粒生长阶段,粘壤土５ｃｍ处的日平均温度最低,为１８．３℃,砂壤土最高,为１９．５℃,中壤居中,为１９．１℃．３种土壤的含水量大小顺序为粘壤＞中壤＞砂壤,粘壤土上小麦籽粒灌浆时间最长,千粒重最高,分别为３８ｄ和４５．５ｇ,砂壤土小麦籽粒灌浆时间最短,千粒重最低,分别为３３ｄ和４２．４ｇ,中壤土小麦２项指标居中,分别为３６ｄ和４３．１ｇ．高产栽培条件下,粘壤土冬小麦产量最高,为８２５３ｋｇ·ｈｍ－２,中壤次之,为７９８０ｋｇ·ｈｍ－２,砂壤最低,为７６１７ｋｇ·ｈｍ－２     

深圳福田白骨壤群落Cr,Ni,Mn的累积及分布

探讨了深圳福田自然保护区白骨壤红树林对Ｃｒ、Ｎｉ、Ｍｎ的吸收、累积及分布．结果表明,该林地土壤Ｃｒ、Ｎｉ、Ｍｎ含量从底层至表层逐步提高;表层（０～３０ｃｍ深）３种元素含量分别为７．９７、２５．０和５３７μｇ·ｇ－１,贮量分别为１０９９．８６、３４５０．００和７４１０６．００ｍｇ·ｍ－２．白骨壤植物各部位Ｃｒ、Ｎｉ、Ｍｎ含量范围分别为０．２８～０．７５、０．４３～７．６５和２５～１５５２μｇ·ｇ－１;植物对表层土壤加权平均富集系数为Ｍｎ＞Ｎｉ≈Ｃｒ．该群落Ｃｒ、Ｎｉ、Ｍｎ的现存累积量分别为６．０６、２０．７６和１６３１．１７ｍｇ·ｍ－２,年净存留累积量分别为０．４３、１．４３和１０７．９８ｍｇ·ｍ－２;林地残留物相应元素储量分别为Ｃｒ７８．００μｇ·ｍ－２、Ｎｉ１５３６．３３μｇ·ｍ－２和Ｍｎ４０５．５４ｍｇ·ｍ－２．该林区３种不同类型群落叶层Ｃｒ、Ｎｉ现存累积量为白骨壤林＞桐花树林＞秋茄林,Ｍｎ为秋茄林＞白骨壤林＞桐花树林．     

中华鲟在成都地区池塘养殖试验报告

１９９３－１９９５年,在四川郫县省水产研究所进行了中华鲟的池塘养殖试验,基本摸清了中华鲟稚幼鱼在内塘里的生活习性及生长特点。全长约３ｃｍ的稚鱼经过１１３ｄ的培育,平均全长为２４ｃｍ,最大个体全长可达２７ｃｍ,体重６０ｇ。幼鱼经过７个月的饲养后鱼体平均全长可达７４ｃｍ,平均体重为１．９ｋｇ。继续饲养一年后,鱼体平均全长为９７．５ｃｍ,体重３．３ｋｇ。最大个体全长１１０ｃｍ,体重５ｋｇ以上。通过两年的     

芋的组织培养

１植物名称芋（Ｃｏｌｏｃａｓｉａｅｓｃｕｌｅｎｔａ）品种江汉芋（多子芋类型）。２材料类别茎尖及微芽。３培养条件分化培养基：（１）ＭＳ＋６－ＢＡ３．０～５．０ｍｇ·Ｌ－１（单位下同）＋ＮＡＡ０．５;（２）ＭＳ＋６．ＢＡ１．０～２．０＋ＮＡＡ０．５。诱导生根培养基：（３）ＭＳ＋６－ＢＡ１．０～２．０＋ＮＡＡ０．１。培养基（１）、（２）中另加蔗糖３０ｇ·Ｌ－１,培养基（３）中加蔗糖１０ｇ·Ｌ１,琼脂６～７ｇ·Ｌ－１,ｐＨ５．８～６．０,１２１℃高温高压灭菌１５ｍｉｎ左右。光照度１５５～２０００ｌｘ,光…     

桃园套种黑牧草对土壤热状况的影响及其模拟研究

在实地试验的基础上,分析和模拟了桃园套种黑牧草对土壤热状况的影响．结果表明,在牧草种植区和自然裸露区,阴天条件下平均土壤容积热容量分别为２．５４和２．５３Ｊ·ｃｍ－３·Ｃ－１,平均土壤导温率分别为１６．９和１０．４ｃｍ２·ｈ－１;土壤净热通量分别为１３６．６和１６７．６Ｊ·ｃｍ－２·ｄ－１;晴天条件下分别为２．９３和２．６１Ｊ·ｃｍ－２·℃－１,１６．３和５．８ｃｍ２·ｈ－１,８０．４和８５．２Ｊ·ｃｍ－２·ｄ－１．不同深度的土壤温度以一阶正弦波形式为主,土壤温度振幅随深度呈指数规律变化,自然裸露区的衰减系数大于牧草种植区;土壤温度位相落后随深度变化为０,４ｈ·ｃｍ－１     

松嫩平原盐碱化草地治理方法的比较研究

采用生物、化学和物理方法对盐碱化草地治理进行了比较研究．生物方法采用枯草处理;化学方法采用石膏处理;物理方法采用铺沙处理,种植羊草、野大麦和碱茅３种牧草．结果表明,３种方法均能降低土壤ｐＨ值、电导率和增加土壤含水率．在生物治理中,羊草和野大麦在枯草量达１５００ｇ·ｍ－２,碱茅在枯草量达１０００ｇ·ｍ－２时,便可良好生长．在化学治理中,石膏施用量达１．２５ｋｇ·ｍ－２,即可达到改良效果．在物理方法治理中,羊草和野大麦在沙层厚度为１３ｃｍ,碱茅在１１ｃｍ时即可正常生长发育．     

内蒙古锡林河流域羊草草原生态系统碳素循环研究

采用野外调查和模型预测方法相结合,对内蒙古锡林河流域一个永久试验样地内的羊草（Ｌｅｙｍｕｓｃｈｉｎｅｎｓｉｓ（Ｔｒｉｎ．）Ｔｚｖｅｌ．）草原群落的碳素贮量、主要流量和周转速度等进行了初步估计,研究了长期过度放牧对整个流域羊草草原土壤有机碳贮量的影响。结果表明：１）羊草群落净初级生产固碳量的多年实测平均值为（２３１．２５±７４．４１）ｇＣ·ｍ－２·ａ－１,向土壤中的碳素输入量为２２０．７５ｇＣ·ｍ－２·ａ－１,土壤呼吸量的模型预测值为（１８１．０３±４６．３２）ｇＣ·ｍ－２·ａ－１;２）该群落碳素输入略大于输出,其理论积累率为１９．８８ｇＣ·ｍ－２·ａ－１,实测积累率为３９．７２ｇＣ·ｍ－２·ａ－１;３）近４０年来,过度放牧致使锡林河流域羊草草原表层（０～２０ｃｍ）土壤的有机碳贮量下降了约１２．４％。     

新疆呼图壁绿洲外缘的盐节木（Halocnemum strobilaceum）及其群落的生物生态学特征

盐节木株丛矮小,高约２０－４０ｃｍ;５月底至８月底净生长高度约３ｃｍ。侧根发达,主要分布在土壤由表层往下水分含量急增、多数情况下盐分逐步降低的２０－４０ｃｍ的土层内,几乎与地表平行伸展,有的长达３ｍ以上。盐节木群落为多汁盐柴类半灌木荒漠中的一个群系。本区记载有８个群丛,分布在地下水位１．０－１．７ｍ、表土层含盐量为４％－８％的盐土上。种类组成贫乏,群落结构简单,总覆盖度３０％－５０％,生物量１０００－２０００ｋｇ／ｈｍ￣２。群落中盐节木、有叶盐爪爪（Ｋａｌｉｄｉｕｍｆｏｌｉａｔｕｍ）具有很高的Ｎａ、Ｓ含量,分别在５００００ｍｇ／ｋｇ、１００００ｍｇ／ｋｇ以上;Ｎａ／Ｋ、Ｎａ／Ｃａ、Ｓ／Ｐ比值为８．５－２６．０,其它植物为１左右;植物中的Ｃａ／Ｍｇ比值为１．０－１．６。盐节木６种元素含量的季节变化,Ｎａ呈增高趋势;其变化曲线与Ｃａ、Ｍｇ相反;Ｎａ、Ｓ曲线相似。盐节木水提取液中具有高的Ｃｌ￣－、含量,ｐＨ为６．６６－６．８４。盐节木群落广泛分布在绿洲外缘的盐碱地上。在盐碱地改良、防止风沙、保护绿洲、牲畜冬春放牧等方面,具有重要的生态经济意义。     

草原土壤N2O释放及全球变暖影响下土壤养分变化的反馈效应

对草原土壤Ｎ２Ｏ释放及其受全球变暖土壤养分变化的影响研究表明,以沼泽泥炭土Ｎ２Ｏ释放量最大,生长季节为１３～１２．２ｋｇＮ·ｈｍ－２·ａ－１,其次灰壤土,为１．５～２．４ｋｇＮ·ｈｍ－２·ａ－１,酸性棕壤最小,为０～３．２ｋｇＮ·ｈｍ－２·ａ－１;Ｎ２Ｏ的释放层灰壤土在０～５ｃｍ,其它２种土壤为０～１０ｃｍ;施肥试验表明,Ｎ、Ｐ肥在生长季节对土壤Ｎ２Ｏ释放量影响不显著,但在生长季末期,Ｎ肥对酸性棕壤及灰壤土Ｎ２Ｏ影响显著,施肥后第３天酸性棕壤由对照的１．３提高到４４．２ｋｇＮ·ｈｍ－２·ａ－１,灰壤土则由对照的１．９提高到３１．１ｋｇＮ·ｈｍ－２·ａ－１,说明全球变暖对土壤有机质分解的影响不会诱发Ｎ２Ｏ释放量的大幅度增加．     

鼎湖山植物群落及其主要植物的热值研究

在测定了南亚热带鼎湖山的４种植物群落３７种主要植物热值的基础上得知：所有这些植物各器官的干重热值和去灰分热值分布范围为：叶片１７２４２．７～２４５３３．３Ｊ·ｇ－１和１８１８８．５～２５８７９．０Ｊ·ｇ－１;根１４９２７．１～１９２８７．８Ｊ·ｇ－１和１５６２０．７～２０３４５．８Ｊ·ｇ－１,枝、干１６１５８．１～２１８１５．９Ｊ·ｇ－１和１６９０８．９～２３０１２．６Ｊ·ｇ－１。呈现叶＞枝或干＞根,地上部分＞地下部分的格局;同一群落从乔木层到草本层,各层次的叶片和平均干重热值是逐渐减小的,且上层乔木单位面积叶片含能量高于下层灌木的,这种格局可能与群落内光照强度的递减有关;同一种植物在演替早期各群落内的热值差距大,而在演替后期各群落内的热值差距小得多,这意味着随群落演替的进行,生境趋同性增大,因而热值接近;各群落内叶片的热值最高,凋落叶的次之,地被物的最小,影响凋落叶释放能量的主要因素不是微生物数量的大小,而可能是温度、淋溶和水分等生态因子。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.