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？     

洪江市:林改改出新天地

<正>6月12日,一场林权拍卖会在洪江市林业产权交易中心大厅热闹开拍。"雪峰山国有林场213亩山场经营权,标的价90万元!"拍卖师亮出了底价。"90.1万元",台下马上有人举起了竞价牌。90.2万元、90.3万元……最后这块山场在激烈     

透视价格话育苗

伴随着西部大开发的强劲脚步 ,植树造林、治理环境已成为各地的重头戏。林木种苗一时因之走红市场 ,价格扶遥直上 ,出现货俏价扬的好势头。今春 ,甘肃省陇东一带的主要造林苗木品类中 ,刺槐每株由去年同期的 0 0 2元～ 0 0 3元涨到 0 0 8元～ 0 1 5元 ,山杏由 0 0 5元～ 0 0 8元涨到 0 1 5元～ 0 2 0元 ,新疆杨由 0 4元～ 0 6元涨到 1 2 0元～ 1 60元。苗木何以走红市场 ?业内人士分析 ,今年苗木俏销价扬势在必行 !其原因主要有五点 :一是苗木市场长期徘徊不前 ,价格低落 ,使育苗面积日渐缩小 ,市场供苗能力削弱 ;二是西部大开…     

供书交友

供玩具厂商名录１０００家，价５０元；新奇特产品１０００家，价３０元；致富机械６００家，价２５元；中药材收购及批发厂商３００家，价２０元；家用电器生产厂８００家，价２０元；全国交友名录１００人，价３元。详细项目付邮资１元即寄。供书交友     

百年红菇村的护林故事

<正>福建省宁化县安远乡董王坑村民朱凤金家门前的一笸箩干红菇,在火辣辣的阳光照射下显得愈发红艳。"今年菇价特别好,每公斤卖640元,我已经卖了快3公斤了!"谈到菇价,朱凤金高兴地说。在董王坑,家家户户都像朱凤金一样,靠着红菇圆了致     

谈南方集体林区山林权属和权益的统一

缺少内在的动力当前,南方集体林区面临的一个重要问题是,森林资源减少,采育比例失调。对于这一问题我们早已有所发觉。因此,早在六十年代就提出了“以营林为基础”的方针。但为什么长期以来这项方针落实不了,采育比例失调的状况扭转不过来呢?有人认为主要归咎于以下三条原因:一是领导不重视;二是营林资金少,三是木材价格低。我认为,林业生产上不去,主要原因不是由于上述三条。因为近年来从中央到地方各级领导都开始重视林业工作。林业投资也有所提高,湖南省的基地造林补助费由原来每亩7元,提高到每亩15元;有的地方加上自筹资金,每亩补助费达40元至50元。木材价     

专业图书、技术资料简介

◆系列丛书《人造板生产质量管理与检验》系统介绍了人造板生产工艺及控制 ;质量管理及质量保证体系 ;有关的人造板国家标准及质量控制的常用方法。邮购价 :2 5元◆系列丛书《制材生产技术》系统阐述了制材理论 ,生产工艺过程 ,设备使用与维修 ,生产线设计及相关国家标准及检验方法等。邮购价 :30元◆系列丛书《胶合板生产技术》系统介绍了胶合板制造理论、生产工艺、设备使用及维修及特种胶合板的生产。邮购价 :33元◆系列丛书《纤维板生产技术》系统阐述了纤维板(含中、高密度板 )制造理论、生产工艺、生产常见问题的产生原因及解决办法。…     

江西森林资源发展现状与对策

详细分析了江西森林资源的数量，质量，时空分布和结构的动态变化；采用多种方法进行森林资源经济评价，估算出林木资产价３１５亿元，竹林价２２．５亿元，林地价１４３亿元，森林价为４８０．５亿元，对森林资源经营管理，林业经济管理体制，林业经营形式，集体林与国有林场经营等方面进行了分析，并对林业经营形式改革进行探讨，提出了分类经营，定向培育，优化结构，合理布局，依托资源搞加工，围绕加工建基地，加工利用紧密结合     

析说牡丹鹦鹉走势

在十年来的商品流通中、牡丹鹦鹉发展迅速,饲养群体不断壮大、并且形成规模性的鸟市场,占有鸟市的主体部分,经过三起三落到１９９７年底鸟价造成登峰造极之势、鸟价离谱扶摇直上,成为一对鸟就有１０００多元的价格,再高的价格可达到１万元。墨黑头、兰黑头,墨水兰等鹦鹉的价格也让人堂舌刮目相看。从１９９８年６月份开始,鸟价大幅度地回落,回落的幅度又使人大吃一惊,从千元一对到百元一对到１０元一对,近日有的牡丹鹦鹉达到５元一对,更有甚者有的牡丹鹦鹉只要价１元１只。北京养鸟者超过２０余万人,人工养的鸟总数超过百万只。这么大的养鸟…     

“桉树热”中叹种子

这几年、由于桉树的用材、造纸、烤油、制板等价值日趋显要,特别是桉叶油的出口销路顿开,使得蓝桉、直干桉等身价倍增。于是乎,这县几千亩,那县上万亩的营造;张家上千株,李家近万株的栽培。全省一片“桉树热”。然而,我省桉树的母树数量有限,种源贫乏,在“桉热”中籽种供求矛盾突出,于是蓝桉、直干按的种价也就暴涨起来。1983年蓝桉每千克14元,现300元;1983年直干桉每千克80元,现3000元。种价猛涨,使得做桉种生意象做黄金生意,有些不     

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]     

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.     

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。     

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。     

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.     

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.