长白山阔叶红松林蒸散量的测算

20 0 1年 7～ 9月应用水量平衡法对长白山阔叶红松林蒸散量进行了测定 ,同时应用波文比(BREB)法对其蒸散量进行了估算 .两种方法得到的总蒸散量分别为 2 88.18mm和 2 14 .94mm ,均小于该时段的降雨量 30 1.9mm .通过两种方法分别得出了各月平均日蒸散量 ,并通过第二种方法计算出了每日的蒸散量及每日不同时刻的蒸散速率 .从而对水量平衡法和BREB方法测算阔叶红松林蒸散量的可行性及其精度进行了验证 .

Retention modeling and simultaneous optimization of pH value and gradient steepness in RP-HPLC using feed-forward neural networks

A novel approach is proposed for the simultaneous optimization of mobile phase pH and gradient steepness in RP-HPLC using artificial neural networks. By presetting the initial and final concentration of the organic solvent, a limited number of experiments with different gradient time and pH value of mobile phase are arranged in the two-dimensional space of mobile phase parameters. The retention behavior of each solute is modeled using an individual artificial neural network. An "early stopping" strategy is adopted to ensure the predicting capability of neural networks. The trained neural networks can be used to predict the retention time of solutes under arbitrary mobile phase conditions in the optimization region. Finally, the optimal separation conditions can be found according to a global resolution function. The effectiveness of this method is validated by optimization of separation conditions for amino acids derivatised by a new fluorescent reagent.

Interweaving of single-helical and equal double-helical chains with the same helical axis in a 3D metal-organic framework

A novel metal-organic framework with unprecedented interweaving of coaxial single-helical and equal double-helical chains of opposite chirality, which features a super-connective helix simultaneously tangling with eight helices, was reported.

Microphase-Separated Brushes on Square Platelets in PS-b-PEO Thin Films

In polystyrene-block-poly(ethylene oxide) thin square platelets can be obtained via fast solvent evaporation by controlling the tethering density (0.08 < sigma < 0.11). The tethering density of the brushes is proportional to the thickness of the PEO crystal and increases with increasing initial solution heating temperature (T-i). When T-i < T-m, where T-m is the melting point of PEO, brushes with microphase-separated structures are observed. The formation of microphase-separated brushes depends on two factors: the strong incompatibility between PS and noncrystalline PEO chains (attached to the crystalline PEO) and the weak interaction between PS-PS brushes.

Synthesis of asymmetric H-shaped block copolymer by the combination of atom transfer radical polymerization and living anionic polymerization

A new asymmetric H-shaped block copolymer (PS)(2)-PEO-(PMMA)(2) has been designed and successfully synthesized by the combination of atom transfer radical polymerization and living anionic polymerization. The synthesized 2,2-dichloro acetate-ethylene glycol (DCAG) was used to initiate the polymerization of styrene by ATRP to yield a symmetric homopolymer (Cl-PS)(2)-CHCCCCH2CH2OH with an active hydroxyl group. The chlorine was removed to yield the (PS)(2)-CHCOOCH2CH2OH ((PS)(2)-OH). The hydroxyl group of the (PS)(2)-OH, which is an active species of the living anionic polymerization, was used to initiate ethylene oxide by living anionic polymerization via DPMK to yield (PS)(2)-PEO-OH. The (PS)(2)-PEO-OH was reacted with the 2,2-dichloro acetyl chloride to yield (PS)(2)-PEO-OCCHCl2 ((PS)(2)-PEO-DCA). The asymmetric H-shaped block polymer (PS)(2)-PEO-(PMMA)(2) was prepared via ATRP of MMA at 130 degrees C using (PS)(2)-PEO-DCA as initiator and CuCl/bPy as the catalyst system. The architectures of the asymmetric H-shaped block copolymers, (PS)(2)-PEO-(PMMA)(2), were confirmed by H-1 NMR, GPC and Fr-IR.

磷虾声学评估系统——接收机及A/D转换器

本文所述为磷虾声学探测系统的一部分——接收机及高速A／D转换器。该系统的设计旨在克服过去南大洋科学考察所用声学评估系统信号补偿不够精确、动态范围较窄、实时处理能力较差等不足。接收机具有宽动态范围及精确的20LoG(R)和40LoG(R)损耗补偿，8位高速A／D转换将数据信号送计算机，使得生物量和声物反射能力的计算得以实时进行。

地震波传播模拟的边界元―体积元积分方程法及其近似求解

To improve the efficiency of boundary-volume integral equation technique, this paper is involved in the approximate solutions of boundary-volume integral equation technique. Firstly, based on different interpretations of the self-interaction and extrapolation operators of the resulting boundary integral equation matrix, two different hybrid BEM+Born series modeling schemes are formulated and validated through comparisons with the full-waveform BE numerical solutions for wave propagation simulation in a semicircular alluvial valley and a complex fault model respectively. Numerical experiments indicate that both the BEM+Born series modeling schemes are suitable for complex geological structures and significantly improve computational efficiency especially for the cases of high frequencies and multisource seismic survey. Then boundary-volume integral equation technique is illuminated in detail and verified by modeling wave propagation in complex media. Furthermore, the first-order and second-order Born approximate solutions for the volume-scattering waves are studied and quantified by numerical simulation in different random medium models. Finally, preconditioning generalized minimal residual method is applied to solve boundary-volume integral equation and compared with Gaussian elimination method. Numerical experiments indicate this method makes the calculations more efficient.

引起红土表层硅铝比值增大原因的可能性探讨

中国南方的红土风化壳，是强烈化学风化作用的产物，被认为是处于或经历了脱硅富铝化阶段。但是在红土剖面上部常常出现Si/Al或SiO2/R2O3比值不降反升的现象，给运用这一指标指示化学风化强度带来了困难。本文通过对贵州平坝、新蒲及花溪碳酸盐岩红色风化壳化学风化程度的研究，以及中国南方几种不同结晶母岩上发育的红土的化学风化强度指标的对比讨论，探讨了产生这种现象的可能性原因。