长白落叶松成片枯死原因的研究

对长白落叶松成片枯死的原因进行了多学科综合研究．结果表明，长白落叶松的成片枯死与病虫害没有直接关系，由于林地高位沼泽的形成，导致根部缺氧呼吸受阻，是落叶松大片枯死的直接诱因．

Low-temperature heat capacity and thermodynamic properties of crystalline carboxin (C12H13NO2S)

Carboxin was synthesized and its heat capacities were measured with an automated adiabatic calorimeter over the temperature range from 79 to 380K. The melting point, molar enthalpy (Delta(fus)H(m)) and entropy (Delta(fus)S(m)) of fusion of this compound were determined to be 365.29 +/- 0.06K, 28.193 +/- 0.09 kJ mol(-1) and 77.180 +/- 0.02 J mol(-1) K-1, respectively. The purity of the compound was determined to be 99.55 mol% by using the fractional melting technique. The thermodynamic functions relative to the reference temperature (298.15 K) were calculated based on the heat capacity measurements in the temperature range between 80 and 360 K. The thermal stability of the compound was further investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The DSC curve indicates that the sample starts to decompose at ca. 290degreesC with the peak temperature at 292.7degreesC. The TG-DTG results demonstrate the maximum mass loss rate occurs at 293degreesC corresponding to the maximum decomposition rate. (C) 2003 Elsevier B.V All rights reserved.

Heat capacity and enthalpy of fusion of pyrimethanil laurate (C24H37N3O2)

Low-temperature heat capacities of pyrimethanil laurate (C24H37N3O2) were precisely measured with an automated adiabatic calorimeter over the temperature range between T = 78 K and T = 340 K. The sample was observed to melt at (321.52 +/- 0.04) K. The molar enthalpy and entropy of fusion as well as the chemical purity of the compound were determined to be (67244 +/- 11) J (.) mol(-1), (209.28 +/- 0.02) J (.) mol(-1) (.) K-1, (0.9943 +/- 0.0004) mass fraction, respectively. The extrapolated melting temperature for the absolutely pure compound obtained from fractional melting experiments was (322.264 +/- 0.006) K. (C) 2004 Elsevier Ltd. All rights reserved.

On the reactivity of Mo species for methane partial oxidation on Mo/HMCM-22 catalysts

By characterizing fresh and used Mo/HMCM-22 catalysts with ICP-AES, XRD, NH3-TPD technique, UV - Vis DRS and UV Raman spectroscopy, the reactivity of Mo species for methane partial oxidation into formaldehyde were directly studied with a new point of view. By comparing the fresh and used catalysts, it was found that the tetrahedral Mo species bonding chemically to the support surface were practically unchanged after the reaction, while the polymolybdate octahedral Mo species, which had a rather weak interaction with the MCM-22 zeolite, leached out during the reaction, especially when the Mo loading was high. Correspondingly, it was found from the time-on-stream reaction data that the HCHO yield remained unchanged, while COx decreased with the reaction time during the reaction. By combining the characterization results and the reaction data, it can be drawn that the isolated tetrahedral molybdenum oxo-species (T-d) is responsible for HCHO formation, while the octahedral polyoxomolybdate species (O-h) will lead to the total oxidation of methane.

New chiral ferrocenyldiphosphine ligand for catalytic asymmetric transfer hydrogenation

New chiral ferrocenyldiphosphine ligands (R)-(S)-3 and (R)-(S)-4 were prepared. The ligands were employed in Ru(II) catalyzed asymmetric transfer hydrogenation of ketones to give corresponding secondary alcohols. Up to 99% conversion with 90% e.e. was obtained on Ru(DMSO)(4)Cl-2/4 in transfer hydrogenation of acetophenones with propan-2-ol. (C) 2003 Elsevier B.V. All rights reserved.

长白山阔叶红松林太阳辐射分光谱特征

根据对林冠上方和林下太阳辐射的观测及气象站资料,分析了长白山阔叶红松林太阳辐射分光谱特征.结果表明,长白山阔叶红松林区太阳总辐射、直接辐射、散射辐射的光合有效辐射系数有一定的日变化和年变化,年平均值分别为046、043、056.阔叶红松林中不同树种的单叶对于太阳总辐射的反射率、透射率、吸收率的平均值分别为270%、234%、496%.单叶的分光谱反射、透射和吸收的特点是,单叶对紫外辐射几乎全部吸收;对光合有效辐射的吸收也很大(718%),透射很小(96%),有一定的反射(186%);对近红外辐射、反射率和透射率接近吸收率小些(269%).林冠分光谱辐射特点是,可见光和紫外辐射主要被林冠吸收(939%、941%),有少量反射和透过;林冠对近红外辐射的吸收较大(592%),有一定的反射(263%),透过较少(144%).

Analytical potential energy function and spectroscopic parameters for the ground and excited states of NaH

set of energies at different internuclear distances for the ground electronic state and two excited electronic states of NaH molecule have been calculated using valence internally contracted multireference configuration interaction(MRCI) including Davidson correction and three basis sets. Then, a potential energy curve (PEC) for each state was determined by extrapolating MRCI energies to the complete basis sets limit. Based on the PECs, accurate vibrational energy levels and rotational constants were determined. The computational PECs are were fitted to analytical potential energy functions using the Murrell-Sorbie potential function. Then, accurate spectroscopic parameters were calculated. Compared with experimental results, values obtained with the basis set extrapolation yield a potential energy curve that gives accurate vibrational energy levels, rotational constants and spectroscopic parameters for the NaH molecule. (C) 2004 Elsevier B.V. All rights reserved.

干旱区地表石油污染物风蚀作用大气传输量估算研究

通过焉耆盆地石油开发区石油污染物水环境污染途径特点的分析 ,认为落地油将通过风蚀作用由大气传输以降尘的形式落入水体 ,对水环境产生影响。本文以土壤侵蚀的风洞实验求得污染源源强 ,采用高斯模式对地表风蚀作用的传输量进行估算 ,进而对石油开发区落地油通过大气传输途径对区域水环境 (博斯腾湖 )的影响进行了预测 ,建立了相应的模型。为人们了解干旱区石油污染物风蚀作用水环境污染影响提供了初步依据 ,对干旱区湖泊石油污染的全面防治提供了科学范式

红松高生长模型的研究(英文)

高生长模型是定量研究树木生长过程的有效途径,本文应用双曲线方程、Logistic方程、三个参数的Richards方程及四个参数的Richards方程对红松的高生长进行了研究。结果表明四个参数的Richards方程在模拟红松高生长时最为合适,且当其参数取不同的数值时,该方程可转化为其它理论方程。在使用四个参数的Richards方程时,可根据立地条件事先给定树高最大值,这样可使模型更符合实际情况。此外,文中还对一种以固定年龄时实际树高为参数值的模型进行了讨论,该模型对于计算给定树木的高生长将更为有效。

基于辅助变量的森林半腐层厚度空间插值精度

基于地统计学方法,利用3种以海拔作为辅助变量的空间插值算法[局部平均的简单kriging法(simple kriging with locally varying mean,SKlm)、带有外部漂移的kriging法(krig-ing with an external drift,KED)和协kriging法(cokrging,COK)]计算了森林半腐层厚度的空间插值精度,并进行了交叉验证.结果表明:KED法既考虑了变量之间的空间变异,又考虑到影响局部空间变化的因素,与其他插值方法相比,其精度有很大提高;由于海拔与半腐层厚度之间的相关关系较弱,导致SKlm法的插值精度没有达到预期效果;COK法直接将海拔用于估计半腐层厚度,由于在边界地区缺乏采样点数据,因此边界地区的插值出现了多处突变区域.对比地统计学方法与距离反比权重法(inverse distance weighting,IDW)在本研究中的插值精度,除了KED方法的插值精度较高外,其余方法的插值精度均不及IDW,原因可能是利用辅助变量辅助地统计学插值时,主、辅助变量之间的相关关系在插值中起着重要作用.

紫色土丘陵区农用地土壤水分动态变化规律研究

依据定位观测数据，对紫色土丘陵区农用地土壤水分的动态变化规律进行了初步研究。结果表明，该区农用地土壤水分的季节变化主要受降水、蒸发和土地利用状况的影响，呈现出明显的三峰三谷型；垂直梯度变化由于受降雨入渗分布与土壤水分向上蒸发的综合作用，基本表现为增长型。并利用标准差和变异系数对土壤水分的垂直梯度变化进行了具体描述和层次划分。最后，通过分析该地区典型农作物及其不同栽培方式对农用地土壤水分的影响，认为优化农作物栽培方式是提高紫色土丘陵区农用地土壤水分利用效率和减少水土流失的有效途径。

黄土高原南部3种农田土壤剖面坚实度的变化规律

为了揭示黄土高原南部地区不同质地类型土壤剖面坚实度的变化及其与土壤含水率的定量关系,以黄墡土、土娄土、裸露在地表的粘化层耕作剖面为研究对象,定位观测其0~45 cm土壤坚实度与含水率的变化。结果表明,黄墡土、土娄土、裸露在地表粘化层耕作剖面的犁底层平均坚实度均大于耕层,犁底层平均坚实度较耕层分别高194.8%,87.3%,10.4%;剖面土壤质地越粘其平均坚实度越大;土壤坚实度与含水率呈负相关关系;土壤坚实度变化速率为0时,以上3种土壤剖面临界含水率分别为0.1712,0.1757,0.1835;质地不同的土壤剖面坚实度时空变化特征有差异,其中黄墡土剖面0~20 cm土层土壤坚实度为350~500 kPa,受土壤含水率变化的影响较小;20~30 cm土层土壤的坚实度为500~1400 kPa,不易受外界环境影响;30 cm以下土层土壤坚实度为700~1600 kPa,受土壤含水率变化影响较大。土娄土剖面0~40 cm土层土壤坚实度为600~1200 kPa,受含水率变化影响较大;40 cm以下土层土壤坚实度稳定在1 800 kPa左右。粘化层剖面0~15 cm土层土壤坚实度在2000 kPa左右,受环境影响较...

内蒙古包头市水环境污染问题及其治理研究

包头市是我国北方干旱地区的重要工业城市,市区占地面积大,人口多,工业企业密集,工业污水及生活污水排放量都很大,造成了市区及其周边地区水环境的严重污染。本文分析了该市水环境的主要污染源、污染物及其污染现状,讨论了本市水环境污染严重的主要原因,并探讨了相应的治理对策。

内蒙古沙地云杉分类的研究

内蒙古沙地云杉究竟是哪一种，在植物分类学上是一个争论性问题。本文通过三种云杉的形态解剖比较、栽培实验观察、同工酶和核型分析以及生态地理分布的研究，结果表明，内蒙古沙地云杉既不同于红皮云杉（ＰｉｃｅａｋｏｒａｉｅｎｓｉｓＮａｋａｉ），也不同于白扦云杉（ＰｉｃｅａｍｅｙｅｒｉＲｅｈｄ．ｅｔＷｉｌｓ．），应划分为一个独立种更为合适，即将原来发表为白扦云杉的变种新组合之为独立的种，沙地云杉（ＰｉｃｅａｍｏｎｇｏｌｉｃａＨ．Ｑ．Ｗｕ）Ｗ．Ｄ．Ｘｕ（ＰｉｃｅａｍｅｙｅｒｉＶａｒ．ｍｏｎｇｏｌｉｃａＨ．Ｑ．Ｗｕ）。