降雨量对科尔沁沙地3种沙生植物生长和生理的影响

对降水格局变化的响应是植物适应环境的重要方面。通过野外增减雨试验,研究了降水变化对科尔沁沙地3种沙生植物生长特性和生理特征的影响。结果表明：（1）6月植被平均密度最大,7月平均盖度最大,降雨量增加60%时,植被盖度最大,为58.0%。（2）增雨区的主要植物为雾冰藜（Bassia dasyphylla）和猪毛菜（Salsola collina）,减雨区主要植物为蒺藜（Tribulus terrestris）,降雨量减少60%时,蒺藜在6、7、8月密度分别为70%、80%、79%,显著高于其他植物。（3）降雨量减少时,3种沙生植物的相对含水量（RWC）减少,而细胞膜透性增加;蒺藜RWC高于雾冰藜和猪毛菜,但是丙二醛（MDA）正好相反;蒺藜的耐脱水能力和细胞膜的耐伤害程度强于雾冰藜和猪毛菜。（4）随着降雨量的增加,3种植物的光能转化效率（F_v/F_m、ΦPSⅡ）逐渐增加,但随干旱天数的增加而减小。     

柔韧性概念在沙生植物中的应用

 植物柔韧性是沙生植物抗风蚀的重要影响因子,柔韧性的研究可对风蚀治理措施的选取及沙地风蚀方程的建立提供一些理论依据。回顾和总结国内外植物柔韧性的研究现状,提出沙生刚性植物和柔性植物的概念,指出现在研究中的不足和今后的研究方向即植物柔韧性的量化测定,柔性植物及刚性植物作用机理,柔性植物与刚性植物的划分和界定,以及植物柔韧性在风洞中的模拟。     

一些沙生植物苗期超弱发光特征研究

测定及分析表明:一些沙生植物种子中高级脂肪酸种类及含量与种子发芽过程中的植物超弱发光参数mv·s/g相关:植物超弱发光和C_(4-18)、棕榈酸含量呈负相关,相关系数分别为-0.8137及-0.9163;和脂肪酸含量成正相关,r=0.9585。另外,各沙生植物都有它们各自的发光特征。     

沙埋对六种沙生植物种子萌发和幼苗生长的影响

分别对6种植物的种子进行0 cm、0.5 cm、1 cm、2 cm、3 cm、4 cm、6 cm、8 cm、12 cm 九个深度的沙埋处理。结果表明：①对于所有的植物种子,0 cm沙埋较浅层沙埋有较低的出苗率;②沙埋对所有植物种子的幼苗出土均有显著的影响(P<0.05),随着埋沙深度的增加,植物幼苗的出土均显著的下降;③植物种子幼苗出土的最大深度与繁殖体的大小呈现显著的正相关性,繁殖体大的植物种能从更深的沙层中出苗。     

沙生植物渗透调节物对干旱、高温的响应及其在抗逆性中的作用

在科尔沁沙地选择不同类型沙地优势植物,测定了其在自然脱水、高温处理及复水后叶可溶性糖、可溶性蛋白质和脯氨酸含量的变化。结果表明,在胁迫过程中流动沙地上的沙米、欧亚旋覆花,叶片内可溶性糖积累,尤其是脯氨酸积累较高,处理12h较处理前分别增加了92.87%、10.28倍,可溶性蛋白质含量下降,在胁迫处理后植株枯死;半固定沙地上的差不嘎蒿可溶性糖增加41.57%、脯氨酸含量增加8.95倍、可溶性蛋白质下降15.04%,在两种胁迫处理后依然存活并恢复生长;固定沙地的白草和狗尾草可溶性糖增加89.82%和89.43%,脯氨酸增加2.49倍和2.53倍、可溶性蛋白质增加。因此,如果把胁迫中叶内积累的脯氨酸与胁迫后植株的存活结合起来看,两种胁迫中差不嘎蒿、狗尾草、白草体内积累的脯氨酸起保护性反应,而沙米、欧亚旋覆花的则是受害症状。     

典型沙生植物差不嘎蒿研究进展与展望

差不嘎蒿（Artemisia halodendron）是我国半干旱沙区特有的菊科蒿属半灌木,具有抗风蚀、耐沙埋、耐高温、耐贫瘠和兼性克隆繁殖等生物学特性,是重要的先锋固沙植物和珍贵的抗逆种质资源,具有较高的生态和生物学开发利用价值。从生物学特性、种群生态学和生理生态适应性等几个方面较系统地评述了国内外关于差不嘎蒿的研究动态及其进展,并在此基础上,提出了差不嘎蒿研究的发展方向及需要进一步关注的关键科学问题,旨在为有效保护和合理利用这一濒临危境的乡土物种提供科学依据。     

一些沙生植物和豆科牧草的稀土效应初探

本文研究了稀土微肥对一些沙生植物和豆科牧草的肥效。研究表明：０．４％稀土微肥浸种可明显提高苗期根系活力；施用稀土一月后，植株叶绿素含量和￣（１４）ＣＯ＿２光合能力均表明，稀土可促进碳代谢；但植株体内Ｋ、Ｍｎ、Ｃａ、Ｆｅ、Ｚｎ、Ｃｕ含量的增加因品种对稀土效应的不同而不同。     

水分和沙埋对4种沙生植物种子萌发和出苗的影响

通过室内试验研究了土壤水分和沙埋深度对4种沙生植物种子萌发和出苗的影响。结果表明:草本雾冰藜（Bassia dasyphylla）种子萌发和幼苗出土喜好水分,水分含量越高,种子发芽率越高;半灌木黑沙蒿（Artemisia ordosica）、灌木沙冬青（Ammopiptanthus mongolicus）和沙棘（Hippophae rhamnoides）种子在含水量为15%~20%的土壤中发芽率高,干旱或水分含量过高会导致种子发芽率降低。沙埋深度显著影响种子的萌发和出苗,雾冰藜种子在无沙埋时发芽率最高,黑沙蒿适宜沙埋深度为0.5 cm,沙冬青和沙棘适宜沙埋深度1.0 cm。     

近地表风沙对植物及植被的影响综述

风沙活动是干旱和半干旱地区,尤其是沙漠和沙漠化地区的重要地表营力过程之一。文章就有关近地表风沙对沙地植物及植被的影响与沙生植物及植被对风沙生境的生态适应对策和响应研究进行了归纳总结,指出了需要进一步加强的研究方向、内容,旨在为进一步深入开展相关研究提供参考与借鉴,为干旱,半干旱沙区植被恢复与重建中防风固沙植物种选择、合理配置、沙区植物资源合理利用与管理提供科技支撑。     

臭氧影响植物生长

我们历来对臭氧层破坏比较关注，但是大气中臭氧含量过多危害也不小。英国出版的《自然》杂志指出，随着大气中臭氧含量的增加，植物的光合作用将受到严重影响，植物对二氧化碳的吸收能力降低，这将加剧全球气候变暖。     

Effect of cryostructures on the uniaxial compressive strength of frozen clay

Unconfined uniaxial compressive tests were performed to study the influence of cryostructure on frozen clay's behavior,such as strain-stress,compressive strength,and failure characteristics,at temperatures varying from-10 to-2°C and strain rates varying from 1.0×10-5to 1.0×10-3s-1.Artificial samples were prepared of three types:(1)integral structure,(2)laminar structure,and(3)reticular structure.The impact of temperature,strain rate,and cryostructure on the mechanical properties is discussed.In general,frozen clay with various cryostructures shows strain-softening behavior in the range of testing temperatures and strain rates.For frozen clay of different cryostructures,the ultimate compressive strength increases with increasing strain rate and decreasing temperature.Under the same testing conditions,the ultimate compressive strengths from high to low are in integral samples,laminar samples,and reticular samples.Failure strain of frozen clay generally increases with increasing temperature and does not indicate any correlation with cryostructure or strain rate.The failure mode of integral and reticular samples was shear failure,while laminar samples showed tensile failure.     

The influence of freeze-thaw cycles on the granulometric composition of Moscow morainic clay

The freeze-thaw cycling process considerably changes the composition,structure,and properties of soils.Since the grain size is the most important factor in determining soil characteristics,our current research primarily aims to investigate dynamic changes of the soil fraction when exposed to freeze-thaw conditions.We observed two series of Moscow morainic clayey specimens(g QmII):(I) the original series,and(II) the remolded series.We subjected each series of soil specimens to different frequencies of freeze-thaw cycles(3,6,20,and 40 cycles),and we used granulometric tests to analyze both series before and after exposure to freeze-thaw conditions.As a result of our experiments,the granulometric compositions tended to be distributed evenly after 40 freeze-thaw processes(i.e.,content of fraction for 0.1–0.05 mm was increased after 40 freeze-thaw cycles) because the division of coarse grains and the aggregation of fine grains were synchronized during the freeze-thaw process.The soil grains in both series changed bi-directionally.In the original series,changes of the sand grains were conjugated with the clay grains,and in the remolded series,changes of the sand grains were conjugated with the silt grains,because potential energy difference caused the division and aggregation processes to relate to the counteraction process.The even distribution of soil grain size indicated the state of equilibrium or balance.The granulometric compositions were altered the most during the sixth freeze-thaw cycle,because the coefficient of the intensity variation of the grain fineness(Kvar) had its maximum value at that time.     

A semi-analytical solution for frost heave prediction of clay soil

Frost heave is one of the main freezing problems for construction in permafrost regions.The Konrad-Morgenstern segregation potential（SP） model is being used in practice for frost heave using numerical techniques.However,the heat release from in-situ and migrated water in the freezing zone could result in some numerical instability,so the simulation of frost fringe is not ideal.In this study,a semi-analytical solution is developed for frost heave prediction of clay soil.The prediction results to the two tests with different freezing mode with clay soil agree well with the tested behavior,which indicates the feasibility of the solution.     

乌兰布和沙漠沙生灌木饲用营养成分的研究

对5种沙生灌木在不同年份和不同季节的饲用营养成分进行了测试分析,并与乌兰布和沙区12种传统饲料的营养成分作了比较,结果表明:5种沙生灌木营养成分和氨基酸含量丰富,部分指标高于紫花苜蓿、沙打旺、玉米秸和小麦秸,适宜于家畜饲养要求;不同灌木或同一灌木在不同年份和不同的季节其主要营养成分含量差异显著,变化规律明显。从营养、产量和采收加工等综合因素考虑,该区灌木饲料采收应在8月下旬进行,该期粗蛋白含量:花棒15.08%、羊柴13.49%、柠条15.99%、梭梭9.10%、沙拐枣10.06%;粗纤维含量:花棒28.69%、羊柴37.94%、柠条34.25%、梭梭24.71%、沙拐枣20.71%;粗脂肪含量:除梭梭外,其他4种灌木均处于生长季含量高值期。5种灌木的钙含量在生长期均递增,磷含量递减,只有羊柴的钙磷比未超过反刍家畜7:1的耐受极限。     

The formation of flocculated clay laminae in the sediments of a meromictic lake

Sediments of Lake Fidler, a meromictic lake in south-west Tasmania, contain distinctive laminae. In order to determine their composition and formation, these laminae were studied using a combination of X- ray analysis, scanning electron microscopy, X-ray diffraction and vibrational spectrometry. Results indicated that the laminae were composed of clay originating from the adjacent Gordon River estuary. The clay was also found as part of the general sediment matrix of the core. The evidence indicates that the laminae are formed during incursions of brackish water from the adjacent Gordon River estuary into Lake Fidler which cause the flocculation of clay minerals in the water column. These clay minerals then sink rapidly to the sediments to form laminae. Although the formation of these laminae pre-dates meromixis, their mode of formation corroborates the theory that meromixis is maintained ectogenically by periodic inflows of brackish water replenishing monimolimnetic salts.     

粘土矿物的提取、鉴定及其古气候意义——以柴达木盆地怀头他拉剖面为例

沉积物中粘土矿物类型主要有自生粘土矿物和碎屑粘土矿物。其中,自生粘土矿物含量较少,是在沉积环境中形成,可能是沉积再循环或成岩作用的产物,可作为沉积环境某方面的指示标志;而碎屑粘土矿物是母岩风化的产物,受沉积环境影响较小,能够有效示踪物源区化学风化过程,进而反映古气候变化。近年来利用碎屑粘土矿物特征来重建物源区古气候的方法得到了广泛的应用。然而,由于粘土矿物主要存在于<2 μm硅酸盐粘粒中,粘土矿物的提取、鉴定比较困难,且自生粘土矿物易受沉积环境等的影响。因此,在利用粘土矿物重建古气候变化时,需慎重选择粘土矿物的提取方法,并考虑物源和沉积环境变化以及成岩作用等对粘土矿物解释的影响。本文以柴达木盆地东北缘怀头他拉剖面硅酸盐粘土矿物的提取、鉴定及其古环境指示意义为例,介绍粘土矿物的提取及应用,为后期粘土矿物研究提供参考。     

钙网蛋白相关信号通路在肿瘤中的研究进展

钙网蛋白（calreticulin,CRT）是参与多种细胞过程的高度保守的内质网伴侣蛋白。1974年,它首次被鉴定为钙离子结合蛋白,随后CRT与肿瘤之间信号通路相关关系被广泛的研究。另外,在人类多种肿瘤中,细胞表面的CRT被认为是1个"促吞噬"信号,由此CRT与癌细胞的巨噬细胞吞噬免疫系统的相关研究,有望为肿瘤综合治疗提供新的理论依据和策略。也有越来越多的证据表明CRT在不同肿瘤中的异常表达,将为CRT成为一种新的肿瘤标志物提供许多依据。以及CRT对各种肿瘤的发展具有很重要的影响且CRT对肿瘤形成和进展的影响取决于细胞类型和临床阶段。