语音识别中一种新的特征参数选择方法

应用正交实验设计方案对语音识别中特征参数的选择进行了计划、分析与实验设计,目的是在大量的特征参数中选择出具有互补作用的特征参数。该方法有4个特点:1)实验方案的构造方法简单,而且得到的实验方案具有各特征参数搭配均衡的特点;2)实验结果分析方法计算简便,计算结果的物理含意明显;3)只需很少的比较实验就可以找到识别性能较好的特征参数组合;4)已有的实验结果对后续实验方案的设计有很好的指导作用。实验结果表明正交实验设计用于特征参数选择是有效的。     

Global patterns in biodiversity

To a first approximation, the distribution of biodiversity across the Earth can be described in terms of a relatively small number of broad-scale spatial patterns. Although these patterns are increasingly well documented, understanding why they exist constitutes one of the most significant intellectual challenges to ecologists and biogeographers. Theory is, however, developing rapidly, improving in its internal consistency, and more readily subjected to empirical challenge.     

翻译文本的多元性与互补性

翻译文本的多元性是一个客观的现象,它受到不同语言、文化,译者的能力、态度与风格以及读者能力与目的等诸多因素的共同影响。每个翻译文本(负责任的翻译)都是对原文某种意义上的忠实表达,不同文本既互相区别又彼此补充,多元文本的共存是翻译实践健康发展的必要条件。     

图分割在Singleton弧相容算法中的应用

基于原有SAC-MP算法,提出一种将图分割技术应用到SAC-MP算法中的一种新算法,该算法在执行时能充分利用图分割技术确定适当的k值,避免了由于k值的不确定带来的冗余操作和盲目性.实验结果表明,该算法在求解约束满足问题时效率较高.     

Projection and contraction methods for nonlinear complementarity problem

We applied the projection and contraction method to nonlinear complementarity problem (NCP). Moveover, we proposed an inexact implicit method for (NCP) and proved the convergence. Foundation item: Supported by the National Natural Science Foundation of China (No. 202001036) Biography: Zhao She-feng (1975-), male, Master candidate, research interest; optimization research.     

生物多样性研究进展

综合了许多研究资料,就生物多样性的内涵及其研究热点进行了综合评述,生物多样性是 所有生物种类、种内遗传变异和它们生存环境的总称,按照空间尺度可分为遗传多样性、物种多样 性、生态系统多样性和景观多样性.并对生物多样性保护作了介绍.     

Ethical scores for animal experiments.

Scientists have for too long been faced with a polarized debate concerning the ethics of animal experiments. An ethical ideal and a practical scoring system would be valuable for the moderate majority.     

Mobility promotes and jeopardizes biodiversity in rock-paper-scissors games

Biodiversity is essential to the viability of ecological systems. Species diversity in ecosystems is promoted by cyclic, non-hierarchical interactions among competing populations. Central features of such non-transitive relations are represented by the 'rock-paper-scissors' game, in which rock crushes scissors, scissors cut paper, and paper wraps rock. In combination with spatial dispersal of static populations, this type of competition results in the stable coexistence of all species and the long-term maintenance of biodiversity. However, population mobility is a central feature of real ecosystems: animals migrate, bacteria run and tumble. Here, we observe a critical influence of mobility on species diversity. When mobility exceeds a certain value, biodiversity is jeopardized and lost. In contrast, below this critical threshold all subpopulations coexist and an entanglement of travelling spiral waves forms in the course of time. We establish that this phenomenon is robust; it does not depend on the details of cyclic competition or spatial environment. These findings have important implications for maintenance and temporal development of ecological systems and are relevant for the formation and propagation of patterns in microbial populations or excitable media.     

Spatial scaling laws yield a synthetic theory of biodiversity.

Ecologists still search for common principles that predict well-known responses of biological diversity to different factors. Such factors include the number of available niches in space, productivity, area, species' body size and habitat fragmentation. Here we show that all these patterns can arise from simple constraints on how organisms acquire resources in space. We use spatial scaling laws to describe how species of different sizes find food in patches of varying size and resource concentration. We then derive a mathematical rule for the minimum similarity in size of species that share these resources. This packing rule yields a theory of species diversity that predicts relations between diversity and productivity more effectively than previous models. Size and diversity patterns for locally coexisting East African grazing mammals and North American savanna plants strongly support these predictions. The theory also predicts relations between diversity and area and between diversity and habitat fragmentation. Thus, spatial scaling laws provide potentially unifying first principles that may explain many important patterns of species diversity.     

Governance and the loss of biodiversity

Most of the world's biodiversity occurs within developing countries that require donor support to build their conservation capacity. Unfortunately, some of these countries experience high levels of political corruption, which may limit the success of conservation projects by reducing effective funding levels and distorting priorities. We investigated whether changes in three well surveyed and widespread components of biodiversity were associated with national governance scores and other socio-economic measures. Here we show that governance scores were correlated with changes in total forest cover, but not with changes in natural forest cover. We found strong associations between governance scores and changes in the numbers of African elephants and black rhinoceroses, and these socio-economic factors explained observed patterns better than any others. Finally, we show that countries rich in species and identified as containing priority areas for conservation have lower governance scores than other nations. These results stress the need for conservationists to develop and implement policies that reduce the effects of political corruption and, in this regard, we question the universal applicability of an influential approach to conservation that seeks to ban international trade in endangered species.     

Human population in the biodiversity hotspots

Biologists have identified 25 areas, called biodiversity hotspots, that are especially rich in endemic species and particularly threatened by human activities. The human population dynamics of these areas, however, are not well quantified. Here we report estimates of key demographic variables for each hotspot, and for three extensive tropical forest areas that are less immediately threatened. We estimate that in 1995 more than 1.1 billion people, nearly 20% of world population, were living within the hotspots, an area covering about 12% of Earth's terrestrial surface. We estimate that the population growth rate in the hotspots (1995-2000) is 1.8% yr(-1), substantially higher than the population growth rate of the world as a whole (1.3% yr(-1)) and above that of the developing countries (1.6% yr(-1)). These results suggest that substantial human-induced environmental changes are likely to continue in the hotspots and that demographic change remains an important factor in global biodiversity conservation. The results also underline the potential conservation significance of the continuing worldwide declines in human fertility and of policies and programs that influence human migration.     

三相分离甾短杆菌胆固醇氧化酶及其性质

三相分离(TPP)是将硫酸铵与叔丁醇混合后形成有机相、中间沉淀相和水相。在20°C,调节发酵上清液的pH至6.0,加入硫酸铵使终浓度为400 g/L,溶解后加入与上清液等体积的叔丁醇,静置1 h分相,胆固醇氧化酶在有机相和水相之间形成蛋白沉淀,12 000 r/min离心10 min收集中间蛋白相,用pH 7.5,10 mmol/L的磷酸缓冲液溶解。结果表明:利用三相分离技术从乳化体系中分离纯化胆固醇氧化酶,比酶活提高了3.49倍,收率达93%。回收的酶液进一步经过DEAE-Sepharose Fast Flow纯化,比酶活从3.56 U/mg提高到30.15 U/mg。该酶最适反应温度为60°C,最适反应pH为7.5,酶的等电点为8.5,该酶在37°C,pH 6.0~8.0较为稳定。Hg2 和Ag 离子完全抑制胆固醇氧化酶的活性。     

环境协调材料的内涵与研究方法

探讨了材料科学的发展与生态环境的关系．分析了环境协调材料的内涵，提出了它的定义．系统地论述了环境协调材料的研究内容和研究方法．     

盐胁迫对番茄幼苗热值、能量积累及分配的影响

研究了基质盐度(0、80、160、240 mmol/L NaCl)对番茄(Lycopersicon esculentumMill.)幼苗热值和能量积累的影响.结果表明:番茄幼苗干物质和能量积累存在低盐促进和高盐抑制的现象,最大值出现在80 mmol/L NaCl处,干物质为6.39 g,能量积累达92.20 kJ.随基质盐度升高,干物质和能量积累倾向于叶片中.番茄幼苗干质量热值和去灰分热值存在不同的变化规律.随盐度升高,根干质量热值和去灰分热值显著增加,而在茎叶和整个植株中,干质量热值逐渐下降,去灰分热值最大值则出现在80 mmol/L NaCl处.