水利工程建设项目中的水土流失防治

水利工程建设项目在建设过程中扰动原地表植被和地下岩土层以及产生大量的堆置废弃物,极易造成水土流失,文章介绍了水利工程建设项目水土流失的现状和形成原因,重点叙述了水利工程建设项目区防止水土流失的水土保持规划设计、措施实施、监测以及监理监督等技术体系,为实践中水利工程建设项目水土流失防治提供指导。     

ASYMPTOTIC STABILITY OF SOLUTION TO THE INITIAL-BOUNDARY VALUE PROBLEM FOR SCALAR VISCOUS CONSERVATION LAWS CORRESPONDING TO RAREFACTION WAVES

1.IntroductionWeconsidertheinitial-boundaryvalueproblem(IBVP)forscalarviscousconservationlaw(ut f(u).=uxx,xE(0, co)=R ,t>0,o,(n \--9,ifI~9,f~M(IBVP){u(0't)=u~(t)-1~i---t:7),[u(x,0)=u000={=:0)f:LO .,wheref"(u)>0foralluunderconsideration,andu--u (1.1),andu~(t)~u~EL'(R ),U'(t)EL'(R ).(1.2)Undercondition(1.l)or(l.l)',thecorrespondingRiemannproblem{;;ot:<:>;i,>=x{,:3'f:,:(13)yieldstherarefaCtionwavesolution(u~)x5f'(u~)t,r"(X,t)=17j,)~1(…     

SPB型泵自冷却分析

根据泵的结构原理，采用在泵体简化图上分块划分控制体积的方法，利用控制体积能量守恒定律，建立SPB泵各存油容腔内工作质温度的微分方程，并求解得出温度的时变规律，进而定量分析SPB泵的自冷却性能。     

Diversity and distribution of marine Gastrotricha along the northern beaches of the state of São Paulo (Brazil), with description of a new species of Macrodasys (Macrodasyida,Macrodasyidae)

Forty-three putative species were found in this first-ever survey of the marine gastrotrich fauna of Brazil. Samples from 23 locations and 37 sites along the northern coasts of the state of São Paulo yielded 21 species of Macrodasyida (12 genera and five families) and 22 species of Chaetonotida (seven genera and two families). Based on morphology, 26 species appear to be taxa not previously described and thus far endemic to Brazil, 13 are known species, while one in each of the genera Diplodasys, Paradasys and Tetranchyroderma remains undetermined. The overall high diversity contrasts with the generally low number of species from single locations, averaging 4.3 (SD 3.5) spp. per location; very few species were found in sites characterized by very fine sand sediment loaded with detritus and by high water turbidity (e.g. 1 sp. in praia da Fazenda), whereas a well-diversified gastrotrich community was found in localities characterized by medium or fine sand with little detritus and clear water (e.g. 14 spp. in praia de Castelhanos). The macrodasyidans, Paraturbanella sp. 1, Pseudostomella sp. 1 and Tetranchyroderma sp. 1, and the chaetonotidan Heteroxenotrichula sp. 1 were the most common species, often sympatric and particularly frequent and abundant along the continental shoreline (recorded in 50–65% of these localities); on the other hand, Macrodasys fornerise n. sp., Ptychostomella sp. 1, Tetranchyroderma sp. 3 and Thaumastoderma sp. 2, while occurring sometimes in very high numbers, exhibited a much narrower range, being encountered only once or twice during the survey. The main morphometric traits are described of the 13 species considered to be cosmopolitan or with at least an amphi-Atlantic distribution, including Chaetonotus apechochaetus and Halichaetonotus marivagus, reported here for the first time from the Americas; of the 26 species thus far endemic to Brazil, Macrodasys fornerise n. sp., which is characterized by a noticeable 145?µm-long frontal organ, is also described and figured.     

地理信息系统在自然保护区经营管理中的应用

地理信息系统作为一种分析与处理空间数据与信息的计算机系统，在生产态学上的应用前景十分广阔。本文从理论与方法上探讨了地理信息系统在自然保护区经营管理中的应用，从应用概况，系统结构以及使用与维护等方面都作了较为详细的阐述。     

贵州生态旅游浅议

本文阐述了生态旅游的概念，分析了发展生态旅游对自然保护区及地方经济发展的影响，并提出发展贵州生态旅游的具体措施     

关于机械能守恒定律的讨论

给出了守恒和守恒定律的定义，并给出了质点组的机械能及机械能守恒定律的表述，还对一些文献关于机械能守恒定律的论述进行了讨论     

对"机械能守恒定律满足力学相对性原理"的补正

系统地阐明机械守恒定律无条件服从相对性原理，总机械如果在一个惯性系守导恒，它就在听有惯性系守恒。     

中国自然保护区管理中地方社区的参与

本文论述了在自然保护区,由于存在土地权属不明确以及在管理中对少数民族为主的地方社区的限制而产生的突出矛盾;事实上地方社区在生物多样性的保护中起到积极的作用,地方社区应该参与到保护区的建设和管理活动中.通过对当前普遍采用的"社区共管模式"的实施效果分析,在全面认识和尊重地方社区对生物多样性保护重要作用的基础上,提出对于未来保护区社区共管要鼓励地方社区的参与,并加强社区参与的能力建设.