六甲氧基甲基三聚氰胺与树脂酸反应的TG—DSC研究

利用热量－差示扫描量热法（ＴＧ－ＤＳＣ）对六甲氧基甲基三聚氰胺（ＨＭＭＭ）与松香树脂酸的反应进行了研究。利用程序升温方法，着重研究了反应的影响因素、催化剂仲类及其用量等。同时，对反应的动力学进行了初步探讨。结果发现，ＨＭＭＭ与树脂酸在融熔状态下的反应比较复杂，重复性较差。而二者在溶液中进行均相反应时则简单得多。反应需在酸催化下进行，对甲苯磺酸（ＰＴＳＡ）的催化效果好，用量为总固体反应物重量的１％～     

Study on Geographic Variation and Genetic Diversity of the Eurasian Beeches

通过对分布于欧洲的水青冈（Ｆａｇｕｓｓｙｌｖａｔｉｃａ和Ｆａｇｕｓｏｒｅｎｔａｌｉｓ）和亚洲的水青冈（Ｆａｇｕｓｊａｐｏｎｉｃａ，Ｆａｇｕｓｃｒｅｎａｔａ，Ｆａｇｕｓｌｕｃｉｄａ，Ｆａｇｕｓｅｎｇｌｅｒｉａｎａ和Ｆａｇｕｓｐａｓｈａｎｉｃａ）的地理历史资料分析和凝胶电泳法等位酶的测定，探讨欧亚大陆水青冈地理变异和遗传多样性．所测定的酶系统包括：过氧化物酶（ＰＸ１和ＰＸ２）、磷酸葡萄糖脱氢酶（ＰＧＤ）、酸性磷酸化酶（ＡＣＰ１和ＡＣＰ２）、超氧化物歧化酶（ＳＯＤ）、谷氨酸草酰乙酸转氨酶（ＧＯＴ１，ＧＯＴ２和ＧＯＴ３）、异柠檬酸脱氢酶（ＩＤＨ）、磷酸果糖异构酶（ＰＧＩ）、甲基萘醌还原酶（ＭＮＲ）、葡萄糖磷酸变位酶（ＰＧＭ１和ＰＧＭ２）和苹果酸脱氢酶（ＭＤＨ１和ＭＤＨ２）１０种酶系统．测定和分析了水青冈遗传相似性、固定指数及遗传多样性随经度、纬度和海拔高度的变化规律，讨论了水青冈起源和分布特点，为进一步研究水青冈的种间关系和地理历史进化过程提供了科学依据．     

高性能模具钢

高性能模具钢该项目包括：１、高强韧低合金冷作模具钢（ＧＤ）；２、高耐磨冷作模具钢（ＧＭ）；３、在７００℃条件下工作的热作模具钢４Ｃｒ３Ｍｏ２ＮｉＶＮｂ（ＨＤ）；４、高韧性易切削塑料模具钢５ＮｉＳＣａ。它可以代替目前常用的钢种，如ＣｒＷＮｎ、Ｃｒ１２、...     

体育教育与林业专业相结合的探讨

体育教育与林业专业相结合的探讨许明（河北林学院体育教研室，保定０７１０００）关键词体育教育，林业专业，相互结合中图分类号Ｇ８０－０５：Ｓ７－０５Ｄ１ＳＣＵＳＳＩＯＮＳＯＮＴＨＥＣＯＭＢＩＮＡＴＩＯＮＯＦＰＨＹＳＩＣＡＬＴＲＡＩＮＩＮＧＷＩＴＨＦＯＲＥ...     

ASARDL项目正式运行

ＡＳＡＲＤＬ项目正式运行“退化土地利用及其社会经济手段研究ＡＬＴＥＲＮＡＴＩＶＥＳＯＣＩＯＥＣＯＮＯＭＩＣＡＰＰＲＯＡＣＨＥＳＴＯＲＥ－ＣＬＡＩＭＩＮＧＤＥＧＲＡＤＥＤＬＡＮＤＳ”（简称ＡＳＡＲＤＬ）项目经近两年的准备，已于１９９５年１０月１日正式运...     

间苯二酚—苯酚—甲醛树脂制备及性能研究

主要研究催化剂、反应时间、摩尔比等反应条件对间苯二酚－苯酚－甲醛（ＲＰＦ）树脂性能的影响，当甲醛／苯酚摩尔比为１￣１．５：１、间苯二酚／苯酚摩尔比为０．６：１时可制得室外级冷固型胶粘剂。通过ＤＳＣ和ＩＲ分析固化行为表明，低温下的放热量主要受多聚甲醛的影响，固化后的树脂中存在着大量的亚甲基醚键。     

桑枝韧皮纤维制浆性能的研究

桑枝韧皮纤维采用碱性亚硫酸盐一蒽醌法制浆，其较合适的工艺条件为：总用碱量为１５％（ＮａＯＨ计），ＮａＯＨ用量为８％（ＮａＯＨ计），Ｎａ＿２ＳＯ＿３用量为１１％（Ｎａ＿２ＳＯ＿３计），蒽醌用量为０．０５％，液比为１：４．最高温度为１６５℃，升温时间２ｈ，保温时间为２．５ｈ；蒸煮粗浆得率为３１．９％，纸浆卡伯值为１４．３９．残余ＮａＯＨ为１．４４ｇ／Ｌ，残余Ｎａ＿２ＳＯ＿３为８．４９ｇ／Ｌ．该浆料采用Ａｐ两段漂白，其Ｈ＿２ＳＯ＿４用量为６％，Ｈ＿２Ｏ＿２用量为３％，浆料可漂至７３．７５％（ＳＢＤ）的白度，漂后细浆得率为２６．８％，α－纤维素含量为９０．７５％     

石灰氮打破葡萄休眠试验

石灰氮打破葡萄休眠试验冯爱华，伊承继（秦皇岛市林业局西山园艺场，秦皇岛０６６１００）（北戴河区农委，秦皇岛０６６１００）关键词石灰氮，休眠，葡萄中图分类号Ｓ６６３．１ＧＲＡＰＥＤＯＲＭＡＮＣＹ－ＢＲＥＡＫＩＮＧＴＥＳＴＷＩＴＨＬＩＭＥ－ＮＩＴＲＯＧＥ...     

β—蒎烯环氧化反应的研究

用低浓度工业级Ｈ２Ｏ２制备过氧乙酸，研究β－蒎烯的环氧反应，重点考察了Ｈ２Ｏ２浓度，反应物投料配比（Ｈ２Ｏ２／β－蒎烯）反应温度和熔剂对环氧化反应的影响，实验结果表明：用５０％的Ｈ２Ｏ２制备过氧乙酸，Ｈ２Ｏ２／β－蒎烯投料摩尔比为２．５：１，在二氯甲烷溶剂中于２０℃反应３ｈ，β－蒎烯转化率达９７．０％，２，１０－环氧蒎烷选择性为８２．７％。     

刺梨汁SOD及其同工酶活力测定和定位染色

用透析法去除Ｖｃ测定刺梨汁ＳＯＤ活力操作简便,结果真实可靠,测得刺梨汁ＳＯＤ活力为５８．８Ｕ／ｍｌ。ＣＨＣｌ３－ＣＨ３ＣＨ２ＯＨ处理测得ＣｕＺｎ－ＳＯＤ３８．４Ｕ／ｍｌ,Ｈ２Ｏ２处理测得Ｍｎ－ＳＯＤ活力为１４．４Ｕ／ｍｌ,ＫＣＮ处理测得Ｍｎ－、Ｆｅ－ＳＯＤ活力为２２．８Ｕ／ｍｌ。聚丙烯酰胶凝胶电泳定位染色法证明刺梨汁具有ＣｕＺｎ－、Ｍｎ－、Ｆｅ－ＳＯＤ３种同工酶。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。