金属板材数控渐进成形螺旋线轨迹生成

在分析金属板材数控渐进成形特点的基础上,指出现行等高线运动成形方式存在的问题,提出了一种基于螺旋运动的数控渐进成形方式和基于STL数据模型的螺旋线成形加工轨迹的生成算法。利用顶点偏置方法生成STL模型的等距模型,采用一系列水平面和与Z轴平行的平面分别切割该等距模型,求出其交线的交点,并将其连接成螺旋线成形加工轨迹。算法应用实例表明,该算法能够生成无干涉的螺旋线成形加工轨迹。     

新疆主要绵羊品种羊毛的氨基酸组成分析

 羊毛是天然蛋白质纤维，其氨基酸组成的变化对羊毛纤维的品质有直接影响。本试验采用还原法从羊毛纤维中提取出经S-羧甲基化修饰的角蛋白，然后水解角蛋白测定氨基酸组成，避免了羊毛中非角蛋白物质和水解破坏胱氨酸对分析结果的干扰。用此法测定新疆绵羊主要品种羊毛的氨基酸组成，结果表明，品质较好的中国美利奴细羊毛，山羊绒毛等有较高的胱氨酸含量。并试从影响角蛋白α螺旋构象的氨基酸组成方面做了初步探讨，结果表明，品质较好的细羊毛均具有较小的螺旋比值。     

Effect of the helix angle of router bits on chip formation and energy consumption during milling of solid wood

The effect of the helix angle of a router bit on chip formation and electric energy per volume (specific energy) under different feed speeds and cutting depths during the milling of maple and China fir by a computer numerically controlled (CNC) router was investigated. The peripheral cutting edge of router bits were custom-made at helix angles of 0°, 2°, 4°, 6°, and 8°. The feed speed varied from 600 to 4800mm/min, and the depths of cut were set at 1,2,3,4, and 6mm. The chips were classified by sieving into a flake type, a splinter type (5 and 10 mesh), a flow type (20 and 40 mesh), and a granule type (< 40 mesh). As the feed speed and the cutting depth increased for the five router bits, more chips of the flake type and the splinter type were produced. However, the number of granule-type chips under the larger helix angle was reduced. The energy per volume removed (specific energy) increased with the feed speed and the depth of cut while milling maple and China fir. More specific energy per cubic centimeter was consumed under the lower feed speeds and the smaller depth of cut. The specific energy can be expressed as a negative power function of the feed speed or the cutting depth for maple and China fir.     

模式贝类Helix aspersa Mueller触角cDNA文库的构建

利用Trizol试剂,从实验室培养的模式贝类散大蜗牛(Helix aspersa)成体触角中提取总RNA;应用SMART技术,反转录合成cDNA第1链,长距离PCR扩增得到双链cDNA,分级分离后将片段插入λTripIEx2,再经包装完成蜗牛触角的cDNA文库构建。经平板培养及蓝白斑法检测,未扩增文库滴度达到1.22×106 pfu/mL,扩增文库滴度达到5.6×109 pfu/mL,重组率达到96.4%以上。挑取部分克隆转成质粒,酶切分析显示插入片段平均长度大约为500 bp。经过上述工作,得到了一个高质量散大蜗牛触角cDNA文库,为进一步研究陆生贝类化学感受相关基因及其与行为的相互关系奠定了基础。     

Functional involvement of Ca(2+) and Ca(2+)-activated K(+) channels in anethol-induced changes in Ca(2+) dependent excitability of F1 neurons in Helix aspersa

The effects of anethol, the major component of anise oil, on the Ca²⁺-dependent excitability and afterhyperpolarization (AHP) in snail neurons were examined using intracellular recording. Anethol (0.5%) significantly broadened the spike, reduced the firing frequency and enhanced the AHP amplitude. In contrast, anethol (2%) significantly increased the firing frequency and decreased the AHP. Blockade of Ca²⁺ channels after anethol application depolarized the membrane potential and significantly reduced the firing rate. Furthermore, in the presence of anethol (0.5%) a significant decrease in the AHP was observed by Ca²⁺ channels blockage. Here, anethol-induced functional modification of Ca²⁺ and Ca²⁺-activated K⁺ channels is suggested.     

Effects of iron pollution on macroinvertebrates promoting organic matter transformation in soils of Presila Cosentina (Italy)

Summary We studied the effect of a component (Fe³⁺) of a polluted atmosphere on the dynamic interactions among biotic and abiotic components of a simulated broad-leaved forest ecosystem in the district of Presila Cosentina. We reproduced, in laboratory trials, the environmental conditions and time sequences of most of the organic and inorganic parameters that affect the activities of microorganisms and of two invertebrates that inhabit broadleaved woods, Helix aspersa and Octolasion complanatum. We stressed this system by treatment with FeCl₃ solution at 60 mg kg^–1 to simulate environmental pollution. The results strongly suggest that heavy metal contamination, which essentially causes oxidative stress at cellular level, is detrimental to many of the parameters measured.     

Synthesis and molluscicidal structure-activity relationships of some novel 1,2,4-triazole N-methyl carbamates

A new series of 1,2,4-triazole derivatives and their corresponding carbamates have been synthesized and screened for their molluscicidal activity against two types of terrestrial snail, Helix aspersa and Theba pisana, by two methods of application, either as contact or as bran baits. Several of the tested compounds exhibited good molluscicidal activity, and T pisana was more sensitive than H aspersa. Substitution at the o- and/or p-positions of the phenyl ring with chlorine or bromine gave higher molluscicidal activity than the unsubstituted compound, with o,p-dichloro substitution being optimum. In addition, compounds containing two triazole moieties showed higher molluscicidal activity, particularly as stomach poisons, than the contact toxic effect of the corresponding compound with one triazole ring. In general, carbamate derivatives were more active than their corresponding 1,2,4-triazole derivatives.     

三螺旋理论视角下的农业科技企业孵化器运行机制研究 ——基于金颖农科孵化器的实证研究

从三螺旋理论入手,以金颖农科孵化器作为实证研究案例,采用个案研究法分析科研院校、企业、政府3个主体相互作用下农业科技企业孵化器的运行机理,探索金颖农科孵化器在以广东省农业科学院为核心的农业类科研院校、农业科技企业以及政府部门间的作用机制.研究表明:农业科技企业孵化器的孵化是科研院校、企业、政府3个螺旋体相互影响下突变的...     

Synthesis and structure–activity relationships for anticipated molluscicidal activity of some 2-amino-5-substituted pyridine derivatives

A series of 2-amino-5-substituted pyridine derivatives was synthesized and their molluscicidal activity against white garden, Theba pisana (Müller), and brown garden, Helix aspersa (Müller), snails was investigated by two methods of application. Some of these compounds showed strong activity under laboratory conditions against the two types of snail. T pisana was more sensitive to the tested compounds than H aspersa. The most effective compounds were 2-amino-5-(benzotriazole-1-ylmethyl)-3-methylpyridine, 2-amino-5-[1-(benzotriazole-1-yl)nonyl]-3-methylpyridine and 2-[(1,2,4-triazole-1-ylmethyl)amino]-3-methylpyridine which exhibited high molluscicidal activity. The toxicity results are discussed in relation to the chemical structures. © 1999 Society of Chemical Industry     

高秆作物立式割台双螺旋输送器参数优化

分析了双螺旋机构立姿输送长茎秆作物的机理;利用室内试验台,通过正交试验找出了影响输送效果的显著因素,通过回归试验找出了显著因素的较优参数值：螺旋输送器转速为319r/min,上下螺旋输送器距离575mm, 螺旋输送器叶片顶端相对动刀水平距离10mm,叶片升角30°。进行了该组参数下的验证试验,综合评价指标达到89.8,能够较好地适应玉米秸秆的立姿输送要求。