全文获取类型
收费全文 | 122篇 |
免费 | 6篇 |
国内免费 | 7篇 |
专业分类
安全科学 | 7篇 |
废物处理 | 2篇 |
环保管理 | 19篇 |
综合类 | 58篇 |
基础理论 | 29篇 |
污染及防治 | 2篇 |
评价与监测 | 3篇 |
社会与环境 | 13篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 9篇 |
2010年 | 5篇 |
2009年 | 11篇 |
2008年 | 5篇 |
2007年 | 11篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有135条查询结果,搜索用时 125 毫秒
101.
Kate L. Palphramand Geraldine Newton-Cross Piran C. L. White 《Behavioral ecology and sociobiology》2007,61(3):401-413
Badgers are carnivores that show considerable variation in their social and spatial organization. At the westernmost part of their range, in Britain and Ireland, variation in spatial organization appears to be determined by the availability of resources. However, the majority of studies has focussed at one end of the social/spatial spectrum, where population densities are high and adjacent territories are contiguous and non-overlapping. To examine whether the same limiting factors appear to apply across a wider range of badger densities, we established a study site in a predominantly coniferous habitat within an upland area of northeast England, where population densities were predicted to be low. Seasonal home ranges of individual badgers were largest in autumn, followed by summer and spring, then winter. This pattern is reflective of the likely seasonal changes in food availability within the area, as opposed to being related to breeding patterns. There were also significant correlations between territory size and the number of grassland patches (positive) and the proportion of grassland (negative), which are consistent with predictions from the Resource Dispersion Hypothesis. Although badgers at the site were living at low to moderate densities relative to many other studied populations in Britain, they showed patterns of spatial organization that were close to those of high-density populations. The nature of the relationship between resource availability and abundance patterns is likely to have important consequences for the conservation and management of badgers and other species that show flexible spatial organization. 相似文献
102.
中国城市化与城镇居民住房 总被引:4,自引:0,他引:4
王晓东 《中国人口.资源与环境》1998,8(1):81-85
随着住房制度改革的不断深入,我国城镇居民人均居住面积有所提高,居住水平有所改善。但是,中国城市化发展的特点很容易造成城镇居民居住水平提高的假象。本文分析了造成这些假象的原因。 相似文献
103.
There is growing interest in the useof forestry-offset projects to mitigate increasingconcentrations of carbon dioxide in the atmosphere. If forestry-offset projects are to be employed broadlyand successfully there need to be accounting rulesthat are easy to operationalize and effective inpreventing cheating. Since carbon is both tangibleand predictable in where it occurs it is feasible todevelop simple accounting rules. Such rules must beconservative with respect to the amount of carboncredited.If accounting practices based on the following simplerules are employed, costs will be kept low andprojects will credit only carbon that is physicallypresent:Changes in living aboveground biomass must always be measured in forestry –offset projects.Belowground living biomass can be estimated from aboveground living biomass in forestry-offset projects. Generalized root/shoot ratios can be used as long as conservative ratios are applied.Not all changes in soil carbon stocks need to be measured, only those for which there is a possibility the stock is declining.The necromass pool need not be measured except when there has been a recent disturbance (interval varies with ecosystem). To insure that inaccurate techniques do not lead to overestimating of carbon stock changes, imprecise estimates of the carbon content of an ecosystem compartment should be discounted.There should be no required level of accuracy associated with estimates of carbon stock changes in forestry-offset projects, but the creditable carbon should be discounted proportional to the uncertainty. 相似文献
104.
浅论循环经济视野下的拾荒者与城市生活垃圾处理问题 总被引:1,自引:0,他引:1
文章简单介绍国内城市生活垃圾处理的现状,探讨城市拾荒者之于城市循环经济的意义,分析社会各界对拾荒者的认识与态度,建议针对我国国情应充分发挥拾荒者经济外部性的正效应,合理控制拾荒者经济外部性的负效应,为我国城市生活垃圾"减量化、无害化、资源化"处理谋求高效低成本的实现方法,以期达到城市循环经济的目标. 相似文献
105.
如何提高处理效果和减少投资,是处理医疗废水的重点.A/O强化二段生物接触氧化 二氧化氯接触消毒工艺综合了厌(兼)氧、好氧以及A-B法的优点,克服了各自的缺点,通过对河南省商丘市第一人民医院的医疗废水处理,证明该工艺是一种处理医疗废水的行之有效的工艺. 相似文献
106.
提出和采用树干输液方法提高大树移栽成活率.该方法具有简便、实用、操作容易、能显著提高移栽成活率等优点,介绍了树干输液方法、输液时期和输液剂量以及营养液的研制等内容. 相似文献
107.
2009年,杭州市上城区统计局民生民意调查中心在全区6个街道开展了市民普遍调查,调查针对市民警遗关心的五项民生内容(计生、安全生产、城市综合治理、居家养老服务、生活居住环境)展开。这份调查材料基本反映了上城区居民群众对民生关注内容的满意程度。文章重点对生活居住环境满意率这一指标进行统计分析。 相似文献
108.
城市生活垃圾复混肥示范工程工艺设计 总被引:3,自引:0,他引:3
提出了适合我国中小城市生活垃圾的处理办法,即利用城市生活垃圾生产有机复混肥。对有机复混肥的效益分析表明,利用城市生活垃圾生产复混具有明显的环境效益,社会效益和的经济效益,是一条利国利民,造福子孙后代的城市生活垃圾处理的好办法。 相似文献
109.
In several vertebrate taxa, males and females differ in the proportions of time they individually devote to vigilance, commonly
attributed to sex differences in intra-specific competition or in absolute energy requirements. However, an effect of sex
on collective vigilance is less often studied (and therefore rarely predicted), despite being relevant to any consideration
of the adaptiveness of mixed- vs single-sex grouping. Controlling for group size, we studied the effect of sex on vigilance
in the sexually dimorphic eastern grey kangaroo Macropus giganteus, analysing vigilance at two structural levels: individual vigilance and the group’s collective vigilance. Knowing that group
members in this species tend to synchronise their bouts of vigilance, we tested (for the first time) whether sex affects the
degree of synchrony between group members. We found that females were individually more vigilant than males and that their
vigilance rate was unaffected by the presence of males. Collective vigilance did not differ between female-only and mixed-sex
groups of the same size. Vigilance in mixed-sex groups was neither more nor less synchronous than in single-sex groups of
females, and the presence of males seemed not to affect the degree of synchrony between females. Sixty-six percent of vigilant
acts were unique (performed when no other kangaroo was alert), and only about one unique vigilant act in every three induced
a collective wave of vigilance. The proportions of vigilant acts that were unique were 60% for females but only 46% for males.
However, the sexes differed little in the rates at which their unique vigilant acts were copied. This limited study shows
that the differences in vigilance between male and female kangaroos had no discernible effect upon collective vigilance. 相似文献
110.
Increasing empirical and theoretical evidence supports the idea that sympatric speciation is operating, for example, in species
flocks comprising several closely related fish species within one lake. Divergent natural selection (promoting spatial and
food niche partitioning) and sexual selection (assortative mating) have been identified as key selection factors in intralacustric
adaptive radiations. However, the evolution of social behaviors accompanying such adaptive radiations is less well understood.
Using a phylogenetically young species flock of pupfish (Cyprinodon spp.) as a model, we examined differences among six sympatric species and compared their shoaling, aggressive, and territorial
behaviors with that of a sister species (C. artifrons). Despite an estimated age of the species flock of less than 8,000 years, pronounced behavioral differentiation was found.
C. simus, the smallest species in the flock, shoaled more than the other species and was less aggressive and less territorial than
C. beltrani. F1-hybrids between C. simus males and C. beltrani females showed an intermediate expression of shoaling and aggressive behavior. Niche partitioning among the members of this
species flock appears to be accompanied by rapid divergent evolution of social behaviors. We discuss the potential role of
phenotypic plasticity and within-species variation of social behaviors for such rapid behavioral diversifications in sympatric
speciation processes. 相似文献