Collapse of gels in an electric field

An infinitesimal change in electric potential across a polyelectrolyte gel produces a discrete, reversible volume change. The volume of the collapsed gel can be several hundred times smaller than that of the swollen gel.     

花样游泳集体自由自选动作中空间和三维空间运用的研究*

集体自由自选动作中空间和三维空间的运用是评判一套花样游泳自由自选编排全面性、艺术创新以及运动员整体能力利用的重要依据之一。以此为创新点，将第28届奥运会、第29届奥运会、第30届奥运会和第14届世界游泳锦标赛顶级赛事上花样游泳取得前六名的队伍为主要研究对象。釆用录像解析统计法、数理统计和逻辑分析法对前述顶级赛事所得到的数据指标进行对比分析，研究花样游泳集休自由自选项目中空间和三维空间运用情况。通过研究得出如下结论：在集体自由自选动作中占领空中优势，发挥立体效果是当前世界花样游泳集体自由自选总体编排的一个新趋势。托举技术是花样游泳占据空间领域的主要技术之一。托举次数、托举组合次数和托举总时间比例是全套动作编排的重要内容和不可忽略的因素。立体队图形也是花样游泳空间技术的主要部分。托举技术三维空间的利用是空中编排总发挥技术亮点和艺术亮点不可缺少的元素。利用好三维空间，创作出更难、更新、更高的托举动作可提升全套动作的技术水平和艺术水平。中国队应在托举次数、托举组合次数、托举时间比例上、立体队图性上改进与提高，以集体自由自选动作中空间的运用，占领空间优势。加强托举的多维，多方向的旋转，提高三维空间的运用。这些方面中国亟待解决的问题。     

Bat flight generates complex aerodynamic tracks

The flapping flight of animals generates an aerodynamic footprint as a time-varying vortex wake in which the rate of momentum change represents the aerodynamic force. We showed that the wakes of a small bat species differ from those of birds in some important respects. In our bats, each wing generated its own vortex loop. Also, at moderate and high flight speeds, the circulation on the outer (hand) wing and the arm wing differed in sign during the upstroke, resulting in negative lift on the hand wing and positive lift on the arm wing. Our interpretations of the unsteady aerodynamic performance and function of membranous-winged, flapping flight should change modeling strategies for the study of equivalent natural and engineered flying devices.     

四氧嘧啶与链脲佐菌素诱导小鼠糖尿病模型的效果比较

用相同总剂量的四氧嘧啶1次给药和2次给药及较大剂量链脲佐菌素1次给药3种方法诱导小白鼠糖尿病模型,多次测定血糖,体重等糖尿病相关指标,以确定糖尿病模型建立的最佳方法。结果表明,四氧嘧啶建模率为91．94％,高于链脲佐菌素建模率(66．7％)(P<0．05);四氧嘧啶建模组的死亡率为15％及体重下降率为 18．1％,均高于链脲佐菌素建模组(死亡率3．3％,体重下降率12．0％)(P<0．05);四氧嘧啶连续2次小剂量给药的建模效果优于1次性大剂量给药。两种药物比较,虽然四氧嘧啶的建模率高于链脲佐菌素,但其对建模小鼠的损害亦明显大于链脲佐菌素,建模时连续小剂量给药,并于4．5～5 h后灌胃质量分数50％葡萄糖,可以降低死亡率, 提高建模率。     

黔东南州洪涝发生规律研究

基于1961~2010年黔东南州16个站逐日降水资料,从1、2和3 d洪涝指标体系出发,分析了黔东南州洪涝的发生、变化和分布规律,结果表明,50年间黔东南州共有46年发生过洪涝,平均每年7.66站次,多洪涝年集中在20世纪90年代以后,洪涝4月开始,10月结束,主要发生在5~9月;黔东南州从西南向东北洪涝逐渐减弱,麻江、丹寨和雷山西部为洪涝高发区;黄平西部、凯里、榕江西部、锦屏北部和从江为洪涝常发区;施秉、剑河、黎平、天柱和岑巩为洪涝少发区;镇远、三穗和台江为洪涝偶发区。     

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.     

Dragonfly flight: novel uses of unsteady separated flows

Studies of insect flight have revealed novel mechanisms of production of aerodynamic lift. In the present study, large lift forces were measured during flight episodes elicited from dragonflies tethered to a force balance. Simultaneously, stroboscopic photographs provided stop-action views of wing motion and the flowfield structure surrounding the insect. Wing kinematics were correlated with both instantaneous lift generation and vortex-dominated flow fields. The large lift forces appear to be produced by unsteady flow-wing interactions. This successful utilization of unsteady separated flows by insects may signal the existence of a whole new class of fluid dynamic uses that remain to be explored.     

Seismic Waves within Earth's Outer Core: Multiple Reflection

Seismic waves reflected as many as four times within Earth's outer core are routinely recorded from large earthquakes. Observations of these waves are confined to rays near grazing incidence on the core-mantle boundary, in agreement with theoretical expectation. Minor adjustments to outer-core velocities may be necessary to account for certain of these arrivals that are not predicted by present core models. A change of 10 kilometers or more in the currently accepted core radius, 3473 kilometers, is not corroborated by the new data.     

Regulation of carcinogen metabolism in the rat ovary by the estrous cycle and gonadotropin

The activity of 7,12-dimethylbenz[a]anthracene hydroxylase in the rat ovary is several times higher in the proestrous phase of the estrous cycle than in the estrous and metestrous plus diestrous phases. Administration of gonadotropin leads to a similar increase in the capacity of the ovary to metabolize xenobiotics. This variation in the activity of 7,12-dimethylbenz[a]anthracene hydroxylase during the estrous cycle may be related to the marked changes in the incidence of ovarian cancer during menopause and in women taking contraceptive pills.     

Leading-edge vortex improves lift in slow-flying bats

Staying aloft when hovering and flying slowly is demanding. According to quasi-steady-state aerodynamic theory, slow-flying vertebrates should not be able to generate enough lift to remain aloft. Therefore, unsteady aerodynamic mechanisms to enhance lift production have been proposed. Using digital particle image velocimetry, we showed that a small nectar-feeding bat is able to increase lift by as much as 40% using attached leading-edge vortices (LEVs) during slow forward flight, resulting in a maximum lift coefficient of 4.8. The airflow passing over the LEV reattaches behind the LEV smoothly to the wing, despite the exceptionally large local angles of attack and wing camber. Our results show that the use of unsteady aerodynamic mechanisms in flapping flight is not limited to insects but is also used by larger and heavier animals.     

科尔沁沙地21种植物水分提升作用的实证检验

对科尔沁沙地21种植物开展了水分提升作用检测和发生特点研究.试验采用上下层土壤隔离的自制栽植箱,通过控制上、下层土壤水分含量的方法检测植物水分提升作用.结果表明:有19个参试物种观测到水分提升作用,水分提升作用可能是沙生植物适应干旱环境的普遍特性;植物水分提升作用在00:00-06:00时段内发生频率和提升数量较高;不...     

柑橘黄龙病老龄果园发病力与时序发生规律研究

为揭示柑橘黄龙病自然感染年序病情发生规律,以提高监测预警防控水平提供科学依据,笔者于2002—2015 年在天然隔离屏障良好的一个老龄果园开展柑橘黄龙病自然感染发病危害研究,在初入侵果园采取3 个重复样地定点定株发病扩散危害系统调查。坚持14 年试验结果表明：柑橘黄龙病自然感染发病力以自然感染发病4~5 年后为最强盛,其发病力可达年新发病率10%~15%,较其初发病力增强2~3 倍;其当年新发病率消长呈“M型”曲线变化规律：第1 自然感染发病显症高峰一般为初次入侵后的第5 年前后,峰期一般为2~3 年;第2 个自然感染发病显症高峰为初次入侵后的第9 年前后,峰期一般为1~3 年,两峰之间为高位波动变化动态。老龄果园黄龙病积年发病呈Logistic 曲线上行变化轨迹,其年序数值化变化模型为Q = 85.81441 EXP( 4.0063-0.5837N )(n=14,r=0.9941**),其自然感染扩散大周期为15年（其中核心为害周期10 年左右）。运用这些变化规律,对提升老龄果园黄龙病监测预警防控具有十分重要的指导意义。     

浮顶油罐举升工艺的研究及应用

针对浮顶油罐结构特点,讨论了浮顶油罐举升方案与举升原理.结合20 000 m3浮顶油罐现场举升试验,介绍了举升工艺的技术要求、浮顶油罐举升的工艺流程及必要的安全和加固措施,并根据试验结果,提出了举升工艺完善和改进的建议.     

高管过度自信与现金股利相关性研究——基于融资约束的视角

针对深海底矿物粗颗粒浆体在提升泵内的流动问题，提出了一种新型粗颗粒-均质浆体两相流动模型．采用流体动力学软件CFX对两级提升泵内的粗颗粒固-液两相湍流进行了数值模拟.计算获得了粗颗粒在提升泵内的流动特征及其泵工作特性的仿真结果，并与两级提升泵的性能试验结果进行对比，两者能较好地吻合，从而验证了该两相流动模型和数值模拟的有效性和准确性.     

豌豆的生长潜能研究

应用一种较适于植物根域环境优化的技术即平台式水平放任栽培技术来进行豌豆的水气培,通过试验研究表明豌豆能在这种环境下表现出超常规发育的生长特性,如单株产量、总体生物量、有效生物转换率、枝蔓叶荚的形态等都发生了巨大变化,使生物量数十倍的提高,使植株发育表现出巨大化与树型化。可以利用该技术栽培出极具观光价值的豌豆树与其他种类繁多的蔬菜树。     

药物浸种处理防治西瓜嫁接苗细菌性果斑病试验

【目的】筛选防治西瓜嫁接苗细菌性果斑病（BFB）的种子处理有效药剂,为防治BFB提供科学依据。【方法】先以17种药剂的200倍液对西瓜种子进行浸种处理,依据嫁接苗BFB的发病率初步筛选防治BFB的有效药剂;以初选有效药剂进行不同浓度、不同混合组合及不同浸种方法处理对嫁接苗BFB的防治效果试验。【结果】初试结果表明,2%春雷霉素处理西瓜嫁接苗BFB病株率较低,可用于下一步试验。复试结果表明,2%春雷霉素100、200、300、400、500倍液浸种处理有籽西瓜种子,嫁接后12 d嫁接苗BFB发病率分别为1.0%、36.7%、94.3%、95.7%、98.1%;2%春雷霉素200倍+乐无病、72%农用链霉素、72%农用硫酸链霉素800倍液浸种处理有籽西瓜种子,嫁接后12 d嫁接苗BFB发病率为1.0%~2.4%;2%春雷霉素100、200、300、400倍液处理西瓜干种子,嫁接后12 d有籽西瓜嫁接苗BFB发病率为0.5%~5.7%,无籽西瓜嫁接苗BFB发病率为8.1%~11.4%;2%春雷霉素400倍+乐无病、72%农用链霉素、72%农用硫酸链霉素1000倍液处理西瓜干种子,嫁接后12 d有籽西瓜嫁接苗BFB发病率为1.0%~2.0%,无籽西瓜嫁接苗BFB发病率为6.7%~9.5%。【结论】2%春雷霉素可作为防治西瓜嫁接苗BFB的首选特效药,推荐浓度为2%春雷霉素400倍或以2%春雷霉素400倍搭配其他杀菌剂使用。     

The greenhouse theory of climate change: a test by an inadvertent global experiment

Since the dawn of the industrial era, the atmospheric concentrations of several radiatively active gases have been increasing as a result of human activities. The radiative heating from this inadvertent experiment has driven the climate system out of equilibrium with the incoming solar energy. According to the greenhouse theory of climate change, the climate system will be restored to equilibrium by a warming of the surfacetroposphere system and a cooling of the stratosphere. The predicted changes, during the next few decades, could far exceed natural climate variations in historical times. Hence, the greenhouse theory of climate change has reached the crucial stage of verification. Surface warming as large as that predicted by models would be unprecedented during an interglacial period such as the present. The theory, its scope for verification, and the emerging complexities of the climate feedback mechanisms are discussed.     

圆盘开沟机刀盘升降装置参数优化的Matlab实现

为了解决圆盘开沟机在下地、过梗、爬坡过程中出现的旋耕刀易破损、刀盘支架易变形等问题,通过对其关键部件的分析研究,以刀盘轴最大提升高度和升降装置最小尺寸为目标函数建立数学模型;用Matlab软件对其结构尺寸进行参数优化.优化结果显示:当油缸支架为113 mm,刀盘轴支承臂为200 mm,刀盘轴回转臂为732 mm时,刀盘轴最大提升高度可达1092 mm.与初始设计相比,刀盘提升效果显著,达到了优化设计的目的.     

不同杀菌剂对蚕豆赤斑病防治效果试验

[目的]探讨不同杀菌剂对蚕豆赤斑病的防治效果及对产量的影响,为生产应用提供科学依据.[方法]201 1年4~6月,于蚕豆结荚初期开始进行不同杀菌剂对蚕豆赤斑病的防治效果试验,药后30 d调查蚕豆赤斑病发病率和病情指数,成熟前调查蚕豆的单株荚数和每荚粒数,收获期调查蚕豆百粒重及产量.[结果]不同杀菌剂处理后,蚕豆赤斑病发病率、病情指数及蚕豆农艺性状有一定差异,其中发病率以50%多菌灵可湿性粉剂处理最低,其次为80%大生M-45可湿性粉剂、裁菌、百泰处理;病情指数以裁菌处理最低,其次为80%大生M-45可湿性粉剂、百泰、50%多菌灵可湿性粉剂、25%咪鲜胺处理;不同杀菌剂处理对单株荚数影响较小;每荚粒数以裁菌处理最多,其次为80%大生M-45可湿性粉剂、50%多菌灵可湿性粉剂、25%咪鲜胺、百泰处理;百粒重以80%大生M-45可湿性粉剂处理最重,其次为裁菌、25%咪鲜胺、50%多菌灵可湿性粉剂、百泰处理;小区产量以80%大生M-45可湿性粉剂处理最高,其次是裁菌、25%咪鲜胺、百泰、50%多菌灵可湿性粉剂处理.[结论]裁菌、80%大生M-45可湿性粉剂、百泰、50%多菌灵可湿性粉剂和25%咪鲜胺的综合防治效果最好,可用于蚕豆赤斑病的防治.     

植物根系的提水作用

在查阅国外大量研究资料的基础上，结合作者几年来的研究结果，对根系提水作用的概念、鉴定、发生数量、研究方法和测定方法以及影响因素进行了论述。并结合中国西北地区干旱半干旱特点和土壤养分与水分分布的空间变异性，探讨了根系提水作用的农学意义，提出了今后开展根系提水作用研究的方向。