乌苏里江国家森林公园生态旅游适宜度评价

论文根据生态旅游的理念,提出生态旅游适宜度评价的概念和原则,并以乌苏里江国家森林公园为例,在确定公园生态旅游适宜度的评价因子的基础上,利用层次分析法对各因子的权重进行赋值,并运用GIS技术,对公园的生态旅游适宜度进行了计算,经分类统计,最适宜开展生态旅游的面积为1814.76hm2(7.9%)、中等适宜的面积为623.44hm2(2.7%)、一般适宜的面积为12209hm2(53.05%)。文章最后针对不同适宜程度对公园开发提出了建议。

植物氨基酸液肥对甜玉米产量及生理指标的影响

在施氮量减少40%的条件下,通过用植物氨基酸液肥拌种、拌种加叶面喷施使甜玉米的生理指标和产量发生明显变化。植物氨基酸液肥有促进甜玉米生长发育、增强生理活性、改善穗部性状、提高商业品质和加工品质的作用。试验还表明,施用植物氨基酸在一定程度上有替代氮化肥的作用。

居民对改善城市水环境支付意愿的研究

运用条件价值评估法,对银川市居民为改善水环境的支付意愿及其影响因素作了初步分析。计算结果显示,研究范围内的居民年平均支付意愿约为17555元/户。回归分析表明,居民家庭年平均收入、教育水平、对现状水环境的满意程度和对供水部门的信任程度等因素对支付意愿有显著影响。

Isomeric polyimides

This review deals with polyimides based on isomeric dianhydrides and diamines, and with chiral polyimides. First, however, a summary is presented of recent work on the synthesis of isomeric dianhydrides, the reaction of mellophanic dianhydride with diamines, and the tendency toward cyclization in reactions of some dianhydrides and diamines. Then turning to polymers, the discussion covers solubility, thermal and dielectric properties, permeability and permselectivity for gas separation, and rheology of isomeric polyimides. Several useful general rules have been found: i.e. the glass transition temperature of polyimides based on isomeric dianhydrides with a given diamine decreases in the order 3,3'- > 3,4'- > 4,4-dianhydride if the polymers are of comparable molecular weight, whereas the thermal stability and the T-beta/T-g ratio (in absolute temperatures) increase in the order of 3,3'- < 3,4'- < 4,4'-dianhydride. Polyimides from 3,3'- or 3,4'-dianhydride have higher solubility than those from 4,4'-dianhydride. Polyimides from 3,4'-dianhydrides exhibit much lower melt viscosity than those from the other isomeric anhydrides. The dielectric constants of polyimides derived from m,m'-diamines are lower than those from p,p'-diamines. Polyimides based on 3,3'- or 3,4'-dianhydrides have higher permeability and slightly lower permselectivity than polyimides based on 4,4'-dianhydrides.

草酸沉淀法合成LiCoO_2正极材料

用草酸沉淀法合成了LiCoO2，用TG、IR、XRD对合成条件和产物结构进行了研究，结果表明最佳的合成条件是：草酸／CoAc2＝1：1、pH＞6、850℃、8h焙烧，首次充电容量可达140mAh／g以上。

氢化物发生-分光光度法连续测定砷和铅

本文提出了以氢化物与硝酸银反应为基础的在一份试样溶液中连续测定微量砷和铅的分光光度法。利用硝酸银-聚乙烯醇-乙醇溶液吸收砷化氢显色测定砷,硝酸银-明胶-乙醇溶液吸收铅化氢显色测定铅。方法灵敏快速,通过稀释有色吸收液可测定砷与铅含量相差较大的样品。应用于沉积物和土壤中砷和铅的分析,获得满意的结果。

冷核聚变的研究概况及争论

“冷核聚变”似乎是1989年世界科技界的头号大新闻。为了满足广大读者想了解这方面真实情况的要求,本期特载《冷核聚变的研究概况及争论》一文。

Identification and characterization of a myeloid differentiation factor 88 (MyD88) cDNA from Zhikong scallop Chlamys farreri

Myeloid differentiation factor 88 (MyD88) is a universal and essential adapter for the TLR/IL-1R family. In this report, the first mollusk Myd88 ortholog (named as CfMyd88) was cloned from Zhikong scallop (Chlamys farreri). The full-length cDNA of CfMyd88 was of 1554 bp, including a 5 '-terminal untranslated region (UTR) of 427 bp, a polyA tail, and an open reading frame (ORF) of 1104 bp encoding a polypeptide of 367 amino acids containing the typical TLR and IL-1R-related (TIR) domain and death domain (DD). Homology analysis revealed that the predicted amino acid sequence of CfMyd88 was homologous to a variety of previously identified Myd88s with more than 30% identity. The temporal expressions of CfMyd88 mRNA in the mixed primary cultured haemocytes stimulated by lipopolysaccharide (LPS) and peptidoglycans (PGN) were measured by real-time RT-PCR system. The mRNA expression of CfMyd88 decreased after stimulation with both LPS and PGN, and the lowest level was about 1/3 times (at 6 h) and 1/10 times (at 9 h) to that in the control group, respectively. The expression then recovered and was upregulated to two-fold at 9 h after LPS stimulation or to the original level at 12 It after PGN stimulation. The results suggest that the MyD88-dependent signaling pathway exists in scallop and was involved in the defense system. (c) 2007 Elsevier Ltd. All rights reserved.

Induction of diploid gynogenesis in turbot Scophthalmus maximus with left-eyed flounder Paralichthys olivaceus sperm

Turbot Scophthalmus maximus exhibits sexually dimorphic growth, with females growing faster and reaching larger adult sizes than males. Thus, development of techniques for preferentially producing females is necessary to optimize production of these species. In this paper, gynogenetic diploids of turbot were induced by activating egg development with ultraviolet (UV)-irradiated left-eyed flounder Paralichthys olivaceus sperm combined with cold shock to prevent extrusion of the second polar body. The results of UV irradiation experiments showed that survival, motility, and duration of activity of P. olivaceus sperm generally decreased with increase in UV dose. The typical Hertwig's effect was observed after fertilized turbot eggs with UV-irradiated P. olivaceus sperm and the optimal UV dose for gynogenetic haploid production was 36,000 erg mm(-2). At 15 degrees C, appropriate timing of cold shock for retention of the second polar body in turbot eggs was at 6 min after fertilization. Results of different combinations of two shock temperatures (1 or 3 degrees C) and four shock durations (15, 25, 35 or 45 min) at 6 min after fertilization demonstrated that shock of 25 min at 1 degrees C gave the highest production of diploid gynogens (39.58% relative to its diploid control). The results of this study reveal that the use of UV-irradiated P. olivaceus sperm for activation of turbot eggs and cold shock for polar body retention is an effective method to produce gynogenetic offspring.

Synthesis and antifungal properties of sulfanilamide derivatives of chitosan

Sulfanilamide derivatives of chitosan (2-(4-acetamido-2-sulfanimide)-chitosan (HSACS, LSACS), 2-(4-acetamido-2-sulfanimide)-6-sulfo-chitosan (HSACSS, LSACSS) and 2-(4-acetamido-2-sulfanimide)-6-carboxymethyl-chitosan (HSACMCS, LSACMCS)) were prepared using different molecular weights of chitosan (CS), carboxymethyl chitosan (CMCS) and chitosan sulfates (CSS) reacted with 4-acetamidobenzene sulfonyl chloride in dimethylsulfoxide solution. The structures of the derivatives were characterized by FT-IR spectroscopy and elemental analysis, which showed that the substitution degree of sulfanilamide group of HSACS, HSACSS, HSACMCS, LSACS, LSACSS and LSACMCS were 0.623, 0.492, 0.515, 0.576, 0.463 and 0.477, respectively. The solubility of the derivatives (pH < 7.5) was higher than that of chitosan (pH < 6.5). The antifungal activities of the derivatives against Aiternaria solani and Phomopsis asparagi were evaluated based on the method of Jasso et al. in the experiment. The results indicated that all the prepared sulfanilamide derivatives had a significant inhibiting effect on the investigated fungi in the polymer concentration range from 50 to 500 mu g mL(-1). The antifungal activities of the derivatives increased with increasing the molecular weight, concentration or the substitution degree. The sulfanilamide derivatives of CS, CMCS and CSS show stronger antifungal activities than CS, CMCS and CSS. (C) 2007 Elsevier Ltd. All rights reserved.

青藏公路取土场高寒草原植被的恢复进程

按照青藏公路建设和整修的不同阶段，利用样方调查植被空间分布变化，得出高寒草原植被的自然演替进程遵循以下规律。在工程结束2年，8年，26年后，群落植被覆盖度和生物多样性指标分别达到原生植被的2％～4％，6％一23％；32％～54％，46％~50％：95％以上和100％左右．青藏公路沿线高寒草原植被的人为破坏影响是明显的，植被的自然恢复需要20年左右的时间．工程建设破坏面积大于1500m~2，植被难以恢复，土壤沙化和水土流失，影响周边地区生态环境质量．因此，在青藏铁路工程建设中首先应当减少对地形地貌的破坏，其次应当重视对地表土壤的保护并辅助人工植被恢复措施，促进植被的自然恢复．

基于Internet的机器人遥操作实验平台的设计与实现

本文介绍了一种面向Internet的机器人遥操作系统实验平台,着重阐述了在平台的设计和实现过程中对数据通信问题的分析和解决。