帮果子狸申冤

质疑一:果子狸是SARS元凶吗?有关专家学者认为,从果子狸体中分离出来的病毒,仅仅是众多冠状病毒的一种,这种病毒是导致SARS病毒“前体”,但不一定是直接导致SARS的病毒,目前媒体上披露的“果子狸是导致SARS病毒的元凶”的说法,也还只是一种推测性的结果。根据现在了解的情况,我们只能够说SARS病毒与野生动物有关,至于关系的程度,还需要进一步分类,进行传染病学实验研究后,才能够确定。5月26日,世界卫生组织也提出了几点疑问:首先,目前的样本都取自一个市场;其次,动物与动物之间的病毒传染可能性也有待研究,因为这些被取标本的果子狸…     

帮食物找搭档

不同的食物含有人体所需的不同营养成分，如果你学会搭配，那你的身体将更加健康。 苹果＋洋葱＋茶叶 荷兰医学研究者认为，苹果、洋葱及茶叶中含丰富的黄酮类物质，可保护心脏。经过对805名65～84岁之间的男子长达5年的观察证明，饮食中的黄酮类物质，主要来自苹果、洋葱和茶叶。坚持每天饮4杯以上茶的男子，死于心脏病的危险减少45％，每天吃一个或一个以上苹果者减少50％。     

我帮外教学汉语

我帮外教学汉语峥嵘岁月○王静华这件事已过去多年，可我至今记忆犹新。当时我在林学院党委办公室工作。１９８７年秋季开学后的一天，李云章院长打来电话，交给我一项特别的教学任务——给我院的美籍英语教师金伯利·莫理斯（ＫｉｍｂｅｒｌｙＭｏｒｒｉｓ）上汉语课。原...     

帮你解除烦恼

烦恼,是我们生活中每个人都会遇到的一种低调情绪.从你来到这个世界开始懂事的时候,烦恼就像你的衣裳一样与你形影不离.孩提时为羡慕人家的玩具或者漂亮衣服而烦恼;上学时为频繁的考试、优良的成绩操心烦恼;大学时为得不到女友的爱情伤心烦恼;毕业后找不到称心如意的工作烦恼;有了爱情为结婚操劳烦恼;工作中为了引起领导的重视、想出人头地而烦恼……总之,人的一生被无数的烦恼所包围、所困惑.     

帮您选择绿化树

春季绿化只有合理选择绿化树种,精心栽培,才能达到理想的绿化效果。工矿企业绿化在工矿企业二氧化硫、硫化氢等有毒有害气体时常散发的区域,可多种植一些垂柳、冬青、大叶黄杨、夹竹桃、广玉兰、碧桃等。在氟化氢浓度大的区域,可多种植一些榆树、桑树、黄杨、泡桐等。在常有少量氯气区域,可多种植一些龙柏、木槿、臭椿、合欢等。     

协会帮商家度过难关

美国：美国家居用品协会和西部家居用品协会与JRM Sales ＆ Management咨询公司合作设立了一个电话热线,帮助零售商度过目前的经济困境。     

律师帮您解难题

我国公民继承境外外国人的遗产步骤和方式是什么?律师同志:我忙于科研,国外的舅舅无子女,生前多次来电话让我去继承遗产,请问:我国公民继承境外外国人的遗产步骤和方式是什么?杜大有我国公民继承在我境外外国人的遗产,可以分以下几个步骤和方式办理: (1)持本人身分证件,被继承人死亡证明书等有关文件,到有管辖权的公证处办得继承权公证书,亲属关系公证书等。     

联帮德国的林业

位于西欧的德意志联邦共和国,国土面积24.8万平方公里,全国可利用林面积725万公顷(包括7万公顷1979年营造的人工幼林),森林覆盖面积680万公顷,林木蓄积量10.4亿立方米,森林覆盖率约29％。人均占有森林面积O.12公顷,人均年消费木材0.6立方米。在所有森林中,乔林占95.4％,矮林占3.5％,中林占1.1％。按权属分,国有林占29(％下同),联邦所有林占1.8,地方行政所有林占22.5,社会和私人团体所有林分别占2.6和3.1,大、中、小林主     

律师帮您解难题

洗衣店将衣服丢失,我能否获得合理赔付?律师同志:一天,我在洗衣店干洗的一套西服被店方丢失,至今未获赔付。当时购买价为3500元,而店方给我的答复是只能赔付500元。请问,我能否获得合理赔付?蔡华健蔡华健同志:你可以拿购买西服的原始发票向该洗衣店主张权利,如果不能达成一致意     

From a strategic to a tactical forest management plan using a hierarchic optimization approach

The Finnish state forest enterprise, Metsähallitus, defines the regional harvest levels for a 10-year period in a strategic-level natural resources plan. Although this plan defines stand-level harvest schedules for all stands, in practice, it cannot be used, as the harvests need to be clustered in time and in space. It is applied by giving each subregion goals they need to fulfill in a tactical level planning process, and the harvests are manually clustered into predefined groups of adjacent stands (departments). In this study, we developed a hierarchical optimization process making use of departments for clustering the harvests. For each of the departments, 91 different stand-level harvest schedules (plans) were determined using incomes from one period and the forest value at the end as objectives. The department-level plans were then used as alternatives in a region-level goal optimization problem. The resulting hierarchic plan was compared to the stand-level solution of the strategic-level plan which served as a benchmark plan. The hierarchical plan clustered the harvests and achieved the goals set better than the benchmark plan, but the net present income was 3.3% lower. The approach turned out usable, but further developing of the approach is needed to reduce the costs of clustering.     

Soil changes after traffic with a tracked and a wheeled forest machine: a case study on a silt loam in Sweden

Alterations to some soil physical parameters were evaluatedafter passes by a tracked forest machine and a wheeled one ofequal mass (about 20 000 kg). Measurements were made after arange of machine passes, with a maximum of eight. The measuredsoil physical parameters were dry bulk density, penetrationresistance, intrinsic air permeability, saturated hydraulicconductivity, porosity and pore-size distribution. Rut depthwas also measured. Although the wheeled machine caused deeper ruts than the trackedone, alterations caused by the two machines to the measuredsoil parameters were similar, except in the uppermost 5–10cm. The wheeled machine caused a decrease in bulk density at5 cm depth, whereas the tracked machine caused an increase,despite its lower ground pressure.     

Spatial pattern of a plant community in a wetland ecosystem in a semi-arid region in northwestern China

The spatial distribution characteristics of plant communities in a wetland-dry grassland ecosystem in arid and semi-arid regions in northwestern China and the main factors affecting the distribution pattern were studied. The Siertan wetland in the Haba Lake Nature Reserve was the study area. Four transect lines, each about 1 km long, were set up in the growing season along the biotope gradient in four directions: east, northeast, west and northwest. Attributes measured include frequency of occurrence, height, density, coverage, biomass and environmental soil factors. The data were analyzed using a two-way indicative species analysis (TWINSPAN), detrended correspondence analysis (DCA) and Spearman correlation coefficients. On this basis, the vegetation in the Siertan wetland was classified into three types and 14 associations. The first vegetation type was halophytic marsh vegetation, mainly distributed in the wetland zone. This type largely contains halophyte and hygric plants and its representative association is Phragmites communis + Kalidium foliatum. The second type was meadow vegetation, distributed in the ecotone. The meadow vegetation species are mainly mesophytic and their representative association is Nitraria tangutorum + Pennisetum flaccidum. The third vegetation type is grassland vegetation, which mainly consists of mesophytic and xerophytes, distributed in the arid grassland zone. The representative association of the third vegetation type is the association of Anaeurolepidium secalium + Saussurea runcinata. Correlation analysis between the axes of DCA and environmental soil factors shows that soil moisture content, organic matter, soil salt content and total nitrogen are the main environmental factors affecting the pattern of vegetation distribution along the biotope gradients from wetland to arid grassland. Other factors affecting the vegetation are microtopography and grazing pressure. Additionally, we have reported modifications and improvements to the importance value methodology. __________ Translated from Journal of Beijing Forestry University, 2008, 30(1): 6–13 [译自: 北京林业大学学报]     

水力旋流器的三维模拟

利用RSM模型模拟计算三维水力旋流器模型,分析了计算结果,并且与相关文献比较后认为：三维模型模拟水力旋流器具有一定的可行性,而二维轴对称模型与实际有一定的差距。     

On-farm research in a silvopastoral project: a case study

The Silvopastoral Project is being implemented by CATIE in the Atlantic humid lowland of Costa Rica, in order to develop alternatives to the current destructive mode of livestock production. The overall approach is briefly described and two superimposed on-farm experiments are discussed in more detail. The main constraints for on-farm research within the project are analysed: the limited previous knowledge of the area and of the local species, the difficulty of achieving a common understanding about research with collaborating farmers, the need for additional staff supervision and the complexity of the statistical analyses. An attempt is made to draw lessons from the ongoing project regarding how to resolve the apparent contradiction between rigorous scientific requirements and questions of immediate value to extension, the compromises to be achieved between different types of evaluation (statistical, risk, etc.) and the potentials and limitations of farmers' participation in research.     

秒杀 陷阱or馅饼

今天,你秒杀了吗?时下,许多网购爱好者都在津津乐道于秒杀话题:马尔代夫度假秒杀价1999元;iPhone手机秒杀价399元……果真有这样的好事?秒杀,就是以压倒性优势一招致命;在极短时     

基于单片机的人造板连续平压热压机分布式温度控制系统的开发

针对连续平压热压机信号分布广、实时性强等特点,利用单片机,开发一种分布式温度控制系统.描述系统的网络架构、硬件组成、软件设计及抗干扰设计方法.系统采用分层分布式模式,结合模块化设计方法,实现连续平压热压机运行过程温度信号的分散采集、实时监测与级联控制.     

无卷筒离合器的轻型绞盘机设计

为适应我国山地丘陵多、坡度陡和绞盘机作业强度大、维护不便等特点,提升绞盘机的操作性和转运能力,设计了一种无卷筒离合器的轻型绞盘机,阐述了绞盘机总体布置方案和工作原理,设计了采用齿轮传动的新型选筒机构,取代传统绞盘机的卷筒离合器,传动可靠,制造工艺简单,对选筒机构的花键轴和齿轮进行了强度校核,并对绞盘机传动系统的主要零部件进行了选型与设计,利用Matlab对绞盘机卷筒进行了轻量化优化设计,利用Solidworks进行了卷筒三维建模和有限元分析。结果表明,优化后的卷筒强度满足要求。该绞盘机采用新型的选筒机构,结构紧凑,安全可靠,整机轻量化程度高,便于运输,操作简便,可以有效提升绞盘机的工作效率。     

Wind Measurements in a Pine Forest During a Destructive Gale

Anemometer readings were recorded during a gale which blew downsome of the trees in an even-aged 16 m stand of Pinus sylvestrison sandy soil at Thetford forest. Gusts at the top of the canopyattained 17•5 m/sec. Wind profiles agreed well with thetheoretical logarithmic profile above the canopy and the exponentialprofile below. During the gale the zero plane displacement androughness length values were similar to those at lower windspeeds. It is therefore possible to estimate wind profiles andthe forces to which a tree in the crop is subjected from measurementsof wind speed at a single point within or above the forest.The wind speeds which blew trees down were much lower than thosepredicted as necessary from ‘tree pulling’ studiesin the same forest. This discrepancy suggests that any considerationof windthrow must take into account the effects of tree vibrationon the deterioration in the strength of the root-soil complex.     

板材拣选抓取搬运

人造板材产品搬运起来很麻烦,抓取提升技术正面临挑战。人造板材在工厂内需要升降和搬运。板材尺寸大,会产生弯曲,而工业4.0时代是“单个尺寸批量生产”,当今的客户却需要混合批次,因此必须从生产线产品堆垛中进行挑选和分类。但是,即使是中等尺寸的板,也是难以抓取升降,而且笨重。从数个不同产品堆垛里,不同规格板中手动拣选大尺寸扁平物品,并将选择出的板堆放在一个单独堆垛中,以交付给定制客户,这是一项通常需要许多员工完成的任务。