梯形明渠水跃共轭水深的优化计算

梯形明渠水跃共轭水深的计算问题在水工消能设计中具有重要意义 ,目前常用的方法有试算法、图解法、近似公式法 ,它们存在计算精度不高、求解复杂、使用不便等缺点。为此 ,本文把该问题等价于两个非线性优化问题 ,建议统一用笔者研制的加速遗传算法 (AGA)来处理。实例的计算结果说明 ,AGA比常用方法简便、计算精度高且具有通用性     

Single-molecule studies of heterogeneous dynamics in polymer melts near the glass transition

Single-molecule spectroscopy was used to follow the orientation of a single probe molecule in a polymer film in real time. Broad spatially heterogeneous dynamics were observed on long time scales, which result from simple diffusive rotational motions on short time scales. This diffusive behavior persists for many rotations before the molecule's local environment changes to one characterized by a new time scale. This environmental exchange occurs instantaneously on the time scale of the experiment and may arise from large-scale collective motions. The distribution of exchange times for these environments was measured for several temperatures near the glass transition.     

Experiments on salt fingers in a hele shaw cell

"Salt fingers" are generated when a slowly diffusing solute overlies a more rapidly diffusing solute in a gravitationally stable fluid. The phenomenon is important in many areas of science; for example, it affects the temperature and salinity structure in the upper half of the ocean, the production of crystals when liquid alloys solidify, and the distribution of properties in magma chambers below the earth's crust. The evolution of a salt finger from initial instability to a fully developed feature is difficult to follow in a fluid because of the close-packed array of cells that is formed. However, when the fluid is contained in a Hele Shaw cell, individual fingers occupy the entire gap width, thereby enabling the experimenter to monitor and record the evolution much more easily. The instability of an array of wide fingers to disturbances that lead to (preferred) smaller scales is documented in a sequence of photographs, and a qualitative, physically consistent argument is offered to explain the instability.     

兽用新药“泻速宁2号”水煎剂的毒性试验

应用兽药筛选中枢神经系统镇痫药物和消化系统运动药物实验法，对“泻速宁2号”水煎剂的毒理作用进行试验研究，结果表明：“泻速宁2号”水煎剂无毒性，并能提高痛阈值和抑制肠管运动，无成瘾性。用药前和用药后绵羊的血液血红蛋白（Hb）、白细胞（Wbc）、红细胞（KBc）、细胞比容（Pcv）均无显著性差异（P＜0．005）。     

基于浑浊度监测山区河流悬浮泥沙含量的试验研究

针对山区河流悬浮泥沙含量监测缺乏实时性的问题,对浑浊度及悬浮泥沙含量进行监测,分析光照强度、流速、颗粒粒径和水体含沙量对浑浊度的影响,建立浑浊度与悬浮泥沙含量的关系模型式。结果表明： 1）光照强度对浑浊度的影响最大,根据二者之间的关系,将光照强度（E）划分为3个区间：E≤6 800 lx、6 800 lx <E≤22 000 lx、E>22 000 lx,对应于3个区间,确定了浑浊度与悬浮泥沙含量的关系模型; 2）水流流速主要影响上层泥沙颗粒的分布,流速为0.16 m/s时测量区域的浑浊度大于流速为0.018 m/s时的浑浊度; 3）泥沙颗粒的粒径大于扬动流速能带动的临界粒径时,其会沉积在渠底,因此,泥沙级配中大于临界粒径的颗粒占比越大,悬浮泥沙含量越小,浑浊度越小; 4）水体含沙量越大,水沙输移过程中携带悬浮泥沙的量也越多,测量区域上层水样的浑浊度越大; 5）采用本研究确定的浑浊度与悬浮泥沙含量的3个关系模型,预测得到的悬浮泥沙含量与实际悬浮泥沙含量的平均相对误差分别为7.22%、10.00%、8.58%。根据在自然条件下不同光照强度区间测得的浑浊度,可以得出该测量区域的悬浮泥沙含量。由于浑浊度可以现场连续、快速测得,所以将此方法引入山区河流悬浮含沙量实时监测是可行的。     

Atrotoxin: a specific agonist for calcium currents in heart

A specific label for voltage-dependent calcium channels is essential for the isolation and purification of the membrane protein that constitutes the calcium channel and for a better understanding of its function. A fraction of Crotalus atrox that increases voltage-dependent calcium currents in single, dispersed guinea pig ventricular cells was isolated. In the doses used, neither sodium nor potassium currents were changed. The fraction was active in the absence of detectable phospholipase or protease activity, and the active component, designated atrotoxin, produced its effect rapidly and reversibly. The effect was produced by extracellular but not intracellular application of the agent. The increase in Ca2+ current was blocked by the Ca2+ channel blockers cobalt and nitrendipine. The active fraction completely blocked specific [3H]nitrendipine binding to guinea pig ventricular membrane preparations. The inhibition of nitrendipine binding by atrotoxin was apparently via an allosteric mechanism. Thus atrotoxin was shown to bind to the Ca2+ channel and to act as a specific Ca2+ channel agonist.     

Quantum phase transition of a magnet in a spin bath

The excitation spectrum of a model magnetic system, LiHoF4, was studied with the use of neutron spectroscopy as the system was tuned to its quantum critical point by an applied magnetic field. The electronic mode softening expected for a quantum phase transition was forestalled by hyperfine coupling to the nuclear spins. We found that interactions with the nuclear spin bath controlled the length scale over which the excitations could be entangled. This generic result places a limit on our ability to observe intrinsic electronic quantum criticality.     

苜蓿、玉米根系提水作用测定的影响因素——植物根系提水作用机理研究Ⅰ

通过一种上干下湿的分根装置,应用中子水分仪在大田条件下研究了苜蓿和玉米根系提水作用测定中几种相关因素的作用和影响,提出了总提水作用的概念和测算模式.结果显示,夜间9 h（20∶00-5∶00）的表观根系提水量（Qm）,一龄苜蓿为8.02 g,开花期的中单2号和豫玉22玉米分别为7.52 g和4.76 g.但其蒸腾失水量（Qt）平均分别为90.26 g4、6.94 g和48.07 g,供试土壤表面的自然蒸发量和上下土层之间隔水层的毛管升水量,苜蓿处理为6.60 g和6,58 g,玉米处理为5.20 g和6.66 g.分别占每株供试苜蓿表观根系提水量（Qm）的11.25倍、82.3%和82.1%,中单2号玉米的6.24倍、69.1%和88.6%,豫玉22玉米的10.1倍、109.2%和139.9%.表明被测植株的蒸腾速率、供试土壤表面水分的自然蒸发和隔水层的毛管作用对植物根系提水作用测定有着及其显著的影响.因此,植物总根系提水量QT应由实际提水量Qp与植株的蒸腾量Qt两部分构成,其中Qp为表观提水量Qm与上层土壤的蒸发量Qe之和再减去隔水层的毛管升水量Qc,即：QT=Qp＋Qt=（Qm＋Qe-Qc）＋Qt.     

Industrial energy in transition: a petrochemical perspective

The future growth of the petrochemical industry depends in part on the industry's ability to improve efficiency in the use of oil and gas feedstocks and to develop promising alternatives. Technological innovation is proving to be the key to the long-term viability of the industry. The next 6 to 7 years will be characterized by the commercialization of new technologies designed to improve the efficiency of petroleum as a feedstock. Union Carbide's advanced cracking reactor, now nearing the demonstration stage, exemplifies this type of effort. The increasing price of oil and gas will make coal-based synthesis gas more attractive as a feedstock, particularly for oxygenated petrochemical products. A further development involves the conversion of biomass, through fermentation, to useful chemical products and the gasification of municipal wastes to raise steam for electricity generation and as a possible, supplemental feedstock. By the year 2000, it is predicted that feedstocks from all sources other than oil and gas may constitute 10 to 14 percent of the total new material requirement for the petrochemical industry.     

虾头食品开发中油炸工艺的试验

本文阐述了以虾头为主原料加工成食品－油虾糊的加工技术。在试验研究的基础上提出油虾糊加工的工艺流程。着重阐述了油炸工序、主要性能参数的试验测定以及油炸设备的性能与应用。     

水库网箱养殖鲤鱼试验

2005年在富川县龟石水库库湾进行网箱养殖鲤鱼试验,试验共设置网箱9只,采用聚乙烯合线制成双层封闭式网箱,面积28hm2,饲养时间150d。结果9只网箱产鱼量达8445.3kg,平均每立方米产鲜鱼156.4kg,增重倍数为6.0,成鱼饲料系数为2.2,投入与产出比为1∶1.53。试验结果表明,网箱养殖鲤鱼技术在富川切实可行,可向全县大面积推广。     

杂交玉米叶面肥肥效试验

10种叶面肥在杂交玉米上施用试验。结果显示，10种叶面肥问的肥效差异不明显，与对照相比，最高肥效的喷施宝玉米增产10％；在高肥土壤上的增加效果不明显。     

海南北运辣椒新品种比较试验

引进甜椒、泡椒，黄皮尖椒，青皮尖椒等4个类型共41个辣椒品种进行多种性状的比较试验，对其果实产量，抗病性，抗逆性，商品性状等进行了综合的评价，4类型中各选出果实产量较高的品种有甜椒的新10号（产量47020kg/hm^2)，泡椒的湘研13号（75610kg/hm^2)，青皮尖椒的佳农8号（55000kg/hm^2)，黄皮尖椒的优美5号（75150kg/hm^2)，这4个品种的综合性状都符合海南北运蔬菜的要求，有进一步推广的价值。     

落叶松幼苗立枯病的田间药剂防治实验

立枯病是落叶松苗期常见的一种病害,其危害严重,我圃在2007-2009年,采用多菌灵、甲醛托布津、敌克松、乙磷铝4种内吸杀菌剂土壤消毒和药剂苗期喷雾相结合的方法,防治效果均在81.6%-90.3%,防治效果显著。     

A wind-forced ekman spiral as a good statistical fit to low-frequency currents in a coastal strait

Ekman's classical analysis of wind-driven currents is a fundamental component of the modern circulation theory of the oceans, but there have been few good observations of the predicted Ekman spiral, where the velocity vector rotates clockwise in direction (in the Northern Hemisphere) and decays exponentially in magnitude with increasing depth. An analysis of recent cyclesonde velocity measurements based on the use of empirical orthogonal functions, however, suggests that a classical Ekman spiral was a good statistical fit to a significant portion of the low-frequency current fluctuations in the Strait of Georgia, British Columbia, for fluctuation periods of about 5 to 10 days.     

高等院校农药学实验教学改革探讨

分析农药学实验教学的现状,探讨农药学实验教学存在的问题及其教改模式,对培养适应现代农业生产技术需要的农药学人才具有一定的指导意义。     

红壤旱地高粱种植密度试验简报

高粱是我国重要的工业原料和饲料.两系杂交高粱"湘两优糯粱1号"是适应南方多熟制条件种植的新优品种,耐旱、再生力强,比地方糯高粱品种增产1倍以上[1].在浙西红壤丘陵区有一定的高粱种植面积,但产量低,市场供不应求.为此我们引进了该品种,并对大田生产的适宜密度进行了试验.     

高等院校植物学创新性实验设计的探讨

大学生创新能力的培养是全面推进素质教育和实施科教兴国战略的关键,而创新性实验是培养和提高大学生创新能力的有效途径。该文结合教学实践,就当前高等院校植物学创新实验的设计中常忽略的几个问题进行讨论和分析．以促进高等院校植物学创新性实验设计更加科学有效。