站在新的历史起点上推进生态文明建设

<正>生态文明的提出是历史的必然人类历史是一部人与自然关系发展的历史,它经历了一个从被动适应到主动适应的过程。在原始社会,即渔猎文明时期,人类只是被动地适应自然,对自然界没有实质性破坏和威胁,并处处受自然界的束缚,形成了原始的文明意识,此间历时百万年。随着农业的诞生,特别是铁器生产工具的出现,人们从被动适应自然过渡到主动适应自然,并出现了农业文明,此间历时万余年。在这一时期,人们为了自身的

湖北省近500年区域干湿序列重建及其比较分析

在历史旱涝记载资料可靠性检验的基础上,重建了湖北省3个区域近500年来的干湿气候变化序列,并比较分析了各区域干湿气候变化的趋势特征、准周期性及跃变现象。结果表明:在3个区域中,鄂东区1570~1770、1890~1950年两个时段偏湿,1470~1520、1790~1830年则偏干;鄂北区偏湿时期主要在1470~1530、1710~1750、1850~1910年三个时段,1470~1530、1770~1830年则偏干;鄂西南区有1550~1610、1650~1710、1830~1890、1930~1990

Effect of the addition of YAG(Y3Al5O12) nanopowder on the mechanical properties of lanthanum zirconate

La2Zr2O7 (LZ) is a promising thermal barrier coating material for the high-temperature applications, which could be significantly toughened by the YAG nanopowder incorporated into the matrix. The composites of xYAG/(1-x)LZ (Y=10, 15, 20 vol. %, LZ-x-YAG) were densified by means of high-pressure sintering (HPS) under a pressure of 4.5 GPa at 1650 degrees C for 5 min, by which a high-relative density above 93% could be obtained. The morphologies of the fractured surfaces were investigated by the scanning electron microscope, and the fracture toughness and Vicker's-hardness of the composites were evaluated by the microindentation. The grain size of the LZ matrix drops significantly with the addition of YAG nanoparticles and the fracture type changes from the intergranular to a mixture type of the transgranular and intergranular in the nanocomposites. The LZ-20-YAG nanocomposite has a fracture toughness of 1.93 MPa m(1/2), which is obviously higher than that of the pure LZ (1.57 MPa m(1/2)), and the toughening mechanism is discussed in this paper.

Efficient green electroluminescent cells using a poly(p-phenylene vinylene) multiblock copolymer sandwiched between carrier-transporting layers

With a newly synthesized poly(p-phenylene vinylene) (PPV) multiblock copolymer used in a triple-layer structure, efficient green light-emitting diodes with low driving voltage have been fabricated. The devices are turned on at 2.5 V, the brightness at 5 V is above 100 cd/m(2) and at 7 V is about 1650 cd/m(2), with an external quantum efficiency of about 1%. (C) 1998 Elsevier Science S.A. All rights reserved.

High-pressure synthesis of gadolinium indium gallium garnet

High-pressure synthesis of garnet Gd3In2Ga3O12 is reported. It was found that the pressure-temperature region for the synthesis of Gd3In2Ga3O12 can be expressed as T(degrees C) < 2350-250P(GPa), and high pressure greatly reduced the reaction time. It was also found that the garnet Gd3In2Ga3O12 decomposed to GdGaO3 and In2O3 under 3.5 GPa and 1650 degrees C, and this process was accompanied by an increasing density of the products and an increasing coordination number for Ga3+ (4 to 6).

Morphological studies on a novel poly(aryl ether ketone)

The morphology of a novel poly(aryl ether ketone) [PEDEKmK] was investigated via polarizing optical microscopy (POM), TEM, DSC, SAXS and electron diffraction (ED). A distinct change in lamellar thickness, orientation, and spherulitic morphology was observed due to crystal melting and recrystallization. However, the crystal packing mode is found to be identical before and after the recrystallization process.

Control of reproduction rhythmicity by environmental and endogenous signals in Ulva pseudocurvata (Chlorophyta)

A field population of Ulva pseudocurvata Koeman et C. Hoek (hereafter termed Ulva) at Sylt Island (North Sea, Germany) exhibited biweekly peaks of gametophytic reproduction during the colder seasons and approximately weekly peaks during summer. The reproductive events lasted 1-5 d and were separated from each other by purely vegetative phases. Under constant conditions in the laboratory, a free-running rhythm was observed with reproductive peaks occurring approximately every 7 d. When artificial moonlight was provided every 4 weeks, fewer reproductive events occurred, and the reproductive rhythm became synchronized to the environmental artificial moonlight rhythm. In the laboratory, apical disks were entirely converted into reproductive tissue after 8 d cultivation, while almost all basal disks stayed vegetative, which prevented the entire loss of the vegetative thallus during reproductive events. Seasonal size reduction of the thallus occurred from late autumn onward and was determined to be controlled by a genuine photoperiodic response, since size reduction could be induced from May onward by experimental short-day (SD) treatment but was prevented in a long-day (LD) or night-break regime (NB). A daily fine-tuning occurred with gamete release early in the morning at the first sign of daylight, following an obligatory dark ("night") period of at least 1 h duration. No release took place if the overnight dark phase was replaced by continuous light. Blue, green, or red light all triggered gamete release after a dark phase at an irradiance of 0.1 mu mol photons . m(-2) .s(-1), while 0.001 mu mol photons . m(-2) . s(-1) was equivalent to a dark control.

末次冰盛期以来黑潮流域的古环境演化

2005年6月，中法国际合作在西太平洋海域执行IMAGES XII-MD147 Micro Polo1航次科学考察时，由法国极地研究所R/V Marine Dufresne极地考察船利用Calypso重力取样器于冲绳海槽南部钻取了34.2米长MD05-2908柱状样。本文利用AMS14C测年数据建立了该孔的年代模型，对该孔的浮游有孔虫动物群落进行了分析，并利用FP-12E浮游有孔虫转换函数和Q型因子分析方法对该孔浮游有孔虫数据进行了研究，对全新世以来的黑潮流系演化和古环境记录进行了讨论。 结果表明，中晚全新世存在着5次洪水爆发期，洪水爆发期与当时温暖气候相对应，而高海平面对洪水的爆发也产生了影响。进入全新世以来的6790～4000a B.P.期间，黑潮流一直有稳步增强的趋势，黑潮流始终位于冲绳海槽内；4000～3000a B.P.期间，黑潮强度减弱或者发生明显东偏，冲淡水影响增强；3000a B.P.以后黑潮强度逐渐增强，1650～0a B.P.为中晚全新世以来黑潮活动最强的时期,在600a B.P.和140a B.P.左右存在低值，黑潮强度短暂减弱。普林虫低值事件在MD05-2908孔中有很好的体现，对该事件进行了进一步定年，其发生时间为3900～2800a B.P.，持续时间为1100a，该事件的发生可能与东亚冬季风加强有关。 冲绳海槽中晚全新世气候变化可以分为四个阶段： 6790～4800a B.P.低温阶段，4800～4100a B.P.高温阶段，4100～2400a B.P.低温阶段，2400～0a B.P.波动高温阶段。通过与中国及世界其它地方对比可以识别出6.3～5.9、5.5、4.6～4.2、3.6～3.0、2.9～2.4、1.3～1.0、0.5～0.1ka B.P.六个降温事件，为全新世气候波动在深海高分辨率沉积记录中的响应提供了有力支持。该孔SST频谱分析结果显示，存在着3008a、1061a这种千年尺度的周期，以及215a、123a、103～107a、81～78a以及73～71a等周期，表明该孔SST变化与太阳活动强度是密切相关的。 中晚全新世以来，黑潮流在冲绳海槽逐步加强，到4000aB.P.左右达到最大，然后4000～3000a B.P.期间，黑潮强度明显减弱或者发生东偏，3000aB.P.以后，黑潮强度持续增强，在近1000aB.P.波动较大。 对冲绳海槽地区14个柱状样氧同位素以及P.obliquiloculata丰度进行研究，发现LGM以来，黑潮流可能仍然在冲绳海槽地区活动，并没有移出海槽外，但是由于其强度减弱，其流径发生了很大变化。

青海湟水流域植物区系研究

湟水流域位于青海省的东部，约处于北纬35°56′－37°38′，东径100°35′－103°05′。属于青藏高原和黄土高原的过滤地带，海拔1650－4394m，全区面积约16600km^2，属于大陆性气候和高原大陆性气候类型。本区共有野生种子植物83科、400属、1234种。分别占本区所属的青藏高原植物亚区唐古特地区总科数的92．22％、总属数的78．74％、总种数的54．00％。研究表明，湟水流域植物区系特征为：（1）在唐古特地区中种类相对较丰富；（2）温带成分占2．80％，以绝对优势确定了本区系为明显的温带性质（属于以北温带成分，特别是欧亚大陆温、寒地带典型成分为优势的，兼具温性，寒温和高寒类型的温带区系性南，或可称为在温带区第中的过渡区系所具有的“复合型”区系特征）；（3）木本类型少，大多数种类为多年生草本植物，缺乏古老和原始类群，一些中国特有种衍生于其广布的亲缘种中，表明本区系具有年轻和衍生的性质；（4）我国西南高山区系和华北区系对该区系具有双重影响；（5）为青藏高原植物亚区唐古特植物地区同华北植物地区相互过渡的代表区系之一；（6）特有属和特有种少。在中国种子植物区系分区中，本区属于青藏高原植物亚区中的唐古特地区。

青海省湟水地区森林灌丛植被遥感分析及其主要特征

湟水地区地处黄土高原和青藏高原过渡带, 界于北纬36°02′～ 37°28′, 东经100°41′～103°04′之间。海拔1650～ 4395m , 总面积为16120 km2。本研究根据卫星遥感影像资料(以TM 为主) , 结合以往野外调查工作, 研究并综合分析了湟水地区的森林、灌丛植被及其主要特征。森林灌丛植被的遥感解译采用综合分析法。研究表明湟水地区森林灌丛植被具有明显的生态地理分布特征, 其分布多集中于黄土低山丘陵与中高山地形结合地带, 即黄土覆盖的边缘交错区域。这一空间分布特征可能与本区的黄土覆盖边缘地区的多样化生态地理特点存在一定的联系。生境的干湿状况直接影响本地区天然林的分布特征、森林灌丛植被覆盖率的高低、森林的类型结构和种类组成, 并成为人工造林效果的重要环境因素。本区森林灌丛植被长期受到人类活动的深刻影响, 具有人类活动的明显痕迹。人类活动的规模范围、作用方式、影响强度等因素成为本区森林灌丛植被及其生境变化与差异的重要原因之一。

基于分形和统计理论的地层非均质研究

Basin-scale heterogeneity contains information about the traces of the past sedimentary cycle and tectonic process, and has been a major concern to geophysicists because of its importance in resource exploration and development. In this paper, the sonic data of 30 wells of Sulige field are used to inverse the power-law spectra slope and correlation length which are measures of the heterogeneity of the velocity of the log using fractal and statistic correlation methods. By taking the heterogeneity parameters of different wells interpolated, we get power law spectra slope and correlation length contours reflecting the stratum heterogeneity. Then using correlation and gradient, we inverse the transverse heterogeneity of Sulige field. Reservior-scale heterogeneity influnce the distribution of remaining oil and hydrocarbon accumulation. Using wavelet modulus maximum method to divide the sedimentary cycle using Gr data, therefore we can calculate the heterogeneity parameter in each layer of each log. Then we get the heterogeneity distribution of each layer of Sulige field. Finally, we analyze the relation between the signal sigularity and the strata heterogeneity, and get two different sigularity profiles in different areas.

非冰期突然气候变化与太阳变化

本文试图介绍发生在非冰期，主要是全新世的突然气候变化研究所取得的进展，包括山地冰川和深海沉积物所记录的全新世突然气候变化，季风和干旱气候突然变化，以及突然气候变化与太阳变化的关系。