四个生长季高浓度CO_2处理长白松的气孔响应(英文)

在长白山站以开顶箱方式对4 年生长白松连续4 个生长季进行CO2 处理,包括700 和500 μmolmol-1 高浓度CO2,以及接受空气CO2的对照箱和不扣箱的裸露地条件(约350 μmolmol-1 CO2),通过测定气孔导度(gs),ci/ca比及气孔数量等指标评价气孔对高浓度CO2的响应。气孔导度及ci/ca比的转换实验表明,在各自生长CO2下和在相同测定CO2 下进行比较时,生长在高浓度CO2 下植株的气孔导度要高于空气CO2 下对照组植株的气孔导度(除700 μmol mol-1 CO2 下的植株在生长CO2 浓度下及在350 μmol mol-1 CO2 下测定时的气孔导度低于裸地植株外)。在各自生长CO2浓度下测定时,高浓度CO2下植株的ci/ca比低于对照组植株,但在相同测定CO2浓度下比较时,却是高浓度CO2下植株的ci/ca高于对照组植株的ci/ca比。高浓度CO2下植株与对照组植株在每单位长度气孔数量上无明显差异,但高浓度CO2通过降低气孔线数使长白松当年生针叶的总气孔数量降低,并且改变了气孔在针叶上、下表面的分配模式。表4 参18。

太阳辐射对长白山阔叶红松林净生态系统碳交换的影响

太阳辐射是植物进行光合作用的前提条件,因此成为影响植被吸收大气CO2的重要环境因子。该研究基于30min通量和常规气象数据,以相对辐射和晴空指数为指标,分析了2003～2006年生长旺季(6～8月)太阳辐射的改变对长白山阔叶红松(Pinus koraiensis)林净生态系统碳交换(Net ecosystem exchange,NEE)的影响。结果表明:天空有一定云层的覆盖对阔叶红松林碳的净吸收有明显的促进作用。4年里6～8月间生态系统最大光合速率在天空有云覆盖时较晴空条件下分别提高了34%、25%、4%和11%。在晴空指数约为0.5的中等辐射条件下,该生态系统的NEE达到最大。对生态系统碳的净吸收有促进作用的临界相对辐射约为37%,而使该生态系统NEE达到最大的最适相对辐射约为75%。进一步分析表明,天空云量的增多和云层厚度的增加会引起散射辐射比例的增加、大气温度和水汽亏缺程度的降低等环境效应,由此可能会导致冠层光合作用的增加和地上部分呼吸的减弱,从而共同决定了净生态系统碳吸收作用的增强。

中国阔叶树干基腐朽两种新病原菌

报道了云南省西双版纳热带雨林地区阔叶树上和四川成都肉桂活树上的两种新的干基腐朽病害,其病原菌为角壳多年卧孔菌(Perenniporia martius(Berk.) Ryvarden)和似雪拟层孔菌(Fomitopsis nivosa(Berk.) Gilb. & Ryvarden)。根据所采集的材料对其进行了详细的形态描述并对病害的症状、分布等进行了讨论。

过去300年中国土地利用、土地覆被变化与碳循环研究

历史时期的土地利用与土地覆被变化是影响陆地生态系统碳循环的重要因素.过去300年间,我国土地利用与覆被发生了较大变化,林地面积迅速减小,垦殖扩张明显,均对陆地生态系统的碳循环产生了重要的影响.采用通过第一手历史文献资料重建的历史土地数据,分析了过去300年我国土地利用变化的主要特征,研究表明:在研究时段,耕地面积持续增加,从清前期1661年的60.78×106hm2增加到20世纪末的96.09×106hm2;森林面积从1700年的248.13×106hm2降至1949年的109.01×106hm2.受土地

Impacts of the Wenchuan Earthquake on the Giant Panda Nature Reserves in China

Ministry of Science and Technology of China [2008BAK47B02, 2008BAC44B04, 2008BAK50B06, 2008BAC43B01, 2006BAC08B06]

聚谷氨酸苄酯脱保护制备聚L-谷氨酸的正交实验研究

聚L-谷氨酸苄酯(PBLG)用体积分数为33%的HBr-醋酸溶液脱保护得到聚L-谷氨酸(PLGA).采用正交实验研究了温度、时间、溶剂及33%HBr-醋酸溶液用量在脱保护过程中对聚L-谷氨酸分子量的影响.结果表明,反应温度越高,时间越长,溶剂二氯乙酸用量越大,PBLG降解越快,得到的PLGA分子量越小;33%HBr-醋酸溶液的影响则相反,随着33%HBr-醋酸溶液用量的增加,反应体系酸性减弱,PBLG溶解度降低,肽键断裂减缓,PLGA分子量也就相对较大

Microstructure and mechanical property of Mg-8.31Gd-1.12Dy-0.38Zr alloy

The Mg-8.31Gd-1.12Dy-0.38Zr (mass%) alloy was prepared by casting technology, and the microstructure, age hardening behavior and mechanical property have been investigated. It is noted that the alpha-Mg and the different Mg-RE (RE = Gd/Dy) compounds are subsistent in the as-cast and annealed state samples. The age hardening behavior is observed during the investigated temperature range, and the alloy exhibits high Vickers hardness, excellent ultimate tensile strength and yield strength at peak hardness.

SrCaSi04：Eu3+的光谱性能的研究木

采用高温固相反应法制备了一种新的用于白光LED的红色荧光粉SrCaSiO4:Eu3+.XRD表明其属于正交晶系,空间群Pmnb;在SrCaSiO4:Eu3+的体系中掺入<12％(原子分数)的Eu3+不会引起相的转变.光谱测试表明,荧光粉的激发峰位于397nm,能与近紫外LED相匹配,其发射峰位于612、592和586nm;在SrCaSiO4:Eu3+的体系中Eu3+的猝灭浓度约为10％(原子分数),其临界传递距离(Re)约为1.2nm.测得样品的衰减曲线,并得到其荧光寿命约为3ms．

Adsorption behaviors of methanol, ethanol, n-butanol, n-hexanol and n-octanol on mica surface studied by atomic force microscopy

The adsorption behavior of methanol, ethanol, n-butanol, n-hexanol and n-octanol on mica surface was investigated by atomic force microscopy. All these alcohols have formed homogeneous films with different characteristics. Upright standing bilayer structure was formed on methanol adsorbed mica surface. For ethanol, bilayer structure and monolayer one were simultaneously formed, while for n-butanol and n-hexanol, rough films were observed. What was formed for n-octanol? Close-packed flat film was observed on n-octanol adsorbed mica substrate, the film was assumed to be a tilted monolayer. The possible adsorption model for each alcohol molecule was proposed according to its adsorption behavior.

Highly efficient electroluminescence from green-light-emitting electrochemical cells based on Cu-I complexes

The complexes [Cu(dnpb)(DPEphos)](+)(X-) (dnpb and DPEphos are 2,9-di-n-butyl-1,10-phenanthroline and bis[2-(diphenyl-phosphino)phenyl]ether, respectively, and X- is BF4-, ClO4-, or PF6-) can form high quality films with photoluminescence quantum yields of up to 71 +/- 7%. Their electroluminescent properties are studied using the device-structure indium tin oxide (ITO)/complex/metal cathiode. The devices emit green light efficiently, with an emission maximum of 523 nm, and work in the mode of light-emitting electrochemical cells. The response time of the devices greatly depends on the driving voltage, the counterions, and the thickness of the complex film. After pre-biasing at 25 V for 40 s, the devices turn on instantly, with a turn-on voltage of ca. 2.9 V. A current efficiency of 56 cd A(-1) and an external quantum efficiency of 16% are realised with Al as the cathode. Using a low-work-function metal as the cathode can significantly enhance the brightness of the device almost without affecting the turn-on voltage and current efficiency. With a Ca cathode, a brightness of 150 cd m(-2) at 6 V and 4100 cd m(-2) at 25 V is demonstrated. The electroluminescent performance of these types of complexes is among the best so far for transition metal complexes with counterions.

A two-dimensional molybdenum (V) phosphate with covalently bonded transition metal coordination complexes: hydrothermal synthesis and structure characterization of Na-2[{Mn(phen)(2)(H2O)}{Mn(phen)(2)}(3){Mn (Mo12O24)-O-V (HPO4)(6)(PO4)(2)(OH)(6)}] center dot 4H(2)O (phen=1,10-phenanthroline)

An organic-inorganic hybrid molybdenum phosphate, Na-2[{Mn(phen)(2)(H2O)} {Mn(phen)(2)}(3){(MnMo12O24)-O-v (HPO4)(6)(PO4)(2) (OH)(6)}] . 4H(2)O (phen=1,10-phenanthroline), involving molybdenum present in V oxidation state and covalently bonded transition metal coordination complexes, has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Deep brown-red crystals are formed in the triclinic system, space group P (1) over bar, a=16.581(l)Angstrom, b=18.354(1)Angstrom, c=24.485(2)Angstrom, alpha=80.589(l)degrees, beta=71.279(1)degrees, gamma=67.084(1)degrees, V=6493.8(8)Angstrom(3), Z=2, lambda(MoKalpha)=0.71073Angstrom (R(F)=0.0686 for 29,053 reflections). Data were collected on a Bruker Smart Apex CCD diffractometer at 293 K in the range of 1.76 < theta < 28.06degrees using omega-2theta scans technique. The structure of the title compound may be considered to be based on {Mo6O12(HPO4)(3)(PO4)(OH)(3)} units bonded together with {Mn(phen)(2)} subunits into a two-dimensional network. Two types of tunnels are observed in the solid of the title compound.

Synthesis of new solid solutions on neodymium-stabilized La2Mo2O9

A new ionic conductor La2-xNdxMo2O9 (x=0.0-2.0) has been synthesized by wet-chemistry method. The precursors and the resultant oxide powders were characterized by DTA/TG, DSC, XRD and XPS techniques. Effect of substituting Nd for La reveals that the phase transition which occurs in La2Mo2O9 around 565degreesC disappears when x>0.2. And the maximum amount of Nd stabilized the high temperature phase of beta-La2Mo2O9 from cubic to tetragonal is about x=1.6. The measurements of impedance spectroscopy indicate that the ionic conductivity becomes considerably higher in comparison to that of La2Mo2O9.