全文获取类型
收费全文 | 342篇 |
免费 | 18篇 |
国内免费 | 21篇 |
专业分类
安全科学 | 20篇 |
废物处理 | 1篇 |
环保管理 | 75篇 |
综合类 | 95篇 |
基础理论 | 93篇 |
环境理论 | 4篇 |
污染及防治 | 20篇 |
评价与监测 | 9篇 |
社会与环境 | 41篇 |
灾害及防治 | 23篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 12篇 |
2019年 | 16篇 |
2018年 | 9篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 8篇 |
2013年 | 19篇 |
2012年 | 12篇 |
2011年 | 37篇 |
2010年 | 12篇 |
2009年 | 18篇 |
2008年 | 20篇 |
2007年 | 21篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 14篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有381条查询结果,搜索用时 15 毫秒
141.
C. A. Kessler 《Environment, Development and Sustainability》2008,10(2):233-247
In Bolivia, recent decentralisation policies have broadened the participation of local actors in development processes. However, development is far from sustainable, and poverty and natural resources degradation still increase. The challenge is to develop strategies that achieve the genuine participation of poor farmers in natural resources management and sustainable development. The logical strategy, which was developed and validated in five Bolivian mountain villages, is an example. In this strategy, first a solid foundation for sustainable development is laid, with activities focussing on five basic conditions for sustainable development in rural villages: leadership and organisation, responsible participation, effective collaboration, mutual trust and environmental awareness. The results show that the existence of a solid foundation is crucial for the success of other development activities, such as soil and water conservation activities. However, given that 2 years after the project’s withdrawal the firmness of the foundation had slightly weakened, it was concluded that a better integration of these villages in local development processes is essential to profit from the new dynamics. This is especially true for soil and water conservation. To achieve this integration, municipalities—with the support of international development agencies—must be encouraged to invest in laying this solid foundation in rural villages and in facilitating follow-up activities to keep the dynamic process going. This study shows that such investments result in better organised villages, more equality, and the genuine participation of more people in sustainable village development. Effective collaboration and accountability at institutional level are, however, required. 相似文献
142.
通过具体的数据资料说明了目前长江水资源已遭受污染的情况,分析了长江主要被污染的河段及其污染的特性,提出了治理长江污染的原则,在此基础上提出了保护长江的策略:建立、健全水资源保护法规,加强监督管理;紧密结合流域规划和经济发展规划,制订和实施流域及重点地区的水资源保护和污染防治规划;控制岸边污染;预测污染负荷并制订预防对策;加强监测以及时发现问题;开展水资源保护重大课题的科研工作。 相似文献
143.
In Lepidoptera, female mating systems range from strict monandry to strong polyandry. Males transfer an ejaculate during
copulation that contains both sperm and accessory gland substances. In butterflies the male ejaculate has at least three effects:
it (1) contains sperm that can fertilize the eggs of the male’s mating partner, (2) influences the refractory period of the
mated female, and (3) contains nutrients that can be used by the female to increase her reproductive output. A number of recent
studies have shown that males in polyandrous mating systems are endowed with adaptations to increase mating capabilities.
Relative to males in more monandrous species they transfer larger first ejaculates which contain relatively more protein,
and allocate proportionally more resources to reproduction. The objective of this study was to compare male reproductive investment
in successive ejaculates, in terms of both mass and quality, to determine if males of polyandrous species are capable of maintaining
the production of larger and more nutritious ejaculates than males of more monandrous species. We used three species of pierid
butterfly, with mating systems ranging from relative monandry to polyandry. The degree of polyandry had a substantial effect
on the reproductive performance of males. The cumulative protein content of ejaculates increased with the degree of polyandry.
Only males of the most polyandrous species, Pieris rapae, produced three successive ejaculates of similar mass and protein content. In the relatively monandrous species, Aporia crataegi and P. brassicae, males in subsequent matings never produced another ejaculate as large as that transferred by males mating for the first
time, although the protein content (mg) of ejaculates did not differ in second and third ejaculates. Moreover, the ability
to remate varied with the degree of polyandry. Given the opportunity to remate, the majority of P. rapae males mated three times, whereas relatively few A. crataegi and P. brassicae males were able to perform three matings. These results suggest that male capacity to produce large, nutritious ejaculates
is limited in relatively monandrous species. In this study only males belonging to the most polyandrous species had the ability
to recuperate quickly from a mating event and remate. Our results suggest that males in polyandrous systems are better adapted
to mating more than once.
Received: 3 November 1995/Accepted after revision: 13 July 1996 相似文献
144.
三峡库区药用植物资源特征及其保护对策 总被引:9,自引:0,他引:9
三峡库区共有药用植物1129种,隶属于603属,174科。菊科、百合科、蝶形花科等19个大科的种数达总种数的494%,蓼属、铁线莲属等26个大属的种数达185%。中国特有种类占372%,显示出其在库区的丰富性。根茎类药用植物占421%,提示我们应适度采挖,做到永续利用。以林地为生境的药用植物占489%,表明森林是库区药用植物的资源库。三峡水库对库区药用植物资源的淹没损失不大,但其间接影响巨大。保护天然林是保护库区药用植物资源的重要途径。 相似文献
145.
Herwig Hulpke Ute Müller-Eisen 《Environmental science and pollution research international》1997,4(3):146-153
Environmentally sound manufacture does not have its source only in developing and improving the techniques for treating solid,
liquid and gaseous wastes at the end of the production process. Our experience shows that more effort and capital budgets
must be devoted to developing preventive measures. Although the treatment techniques have become very advanced and meet ecological
requirements to a very high degree, they are now reaching the limits of their technological and economic feasibility. Environmental
protection at the production site has undergone structural change in recent years. The emphasis has shifted to preventive
techniques which affect the production process itself, avoiding the emergence of waste at the “end of the pipe” by preventing
its formation or recycling it straight away. This integrated approach is in harmony with the demands of sustainable production.
The functions of in-process environmental protection measures need to be looked at as a whole from the points of view of both
environmental protection and cost-effectiveness. Some integrated methods are described. 相似文献
146.
Kai Lindström Colette M. St. Mary Christophe Pampoulie 《Behavioral ecology and sociobiology》2006,60(1):46-51
Male parental care is typically thought to come at a cost to mate attraction and future mating success. However, it has also
been hypothesized that paternal care may be under sexual, as well as natural, selection, such that good fathers actually attract
more mates. Here we show experimentally that in the sand goby, Pomatoschistus minutus, females prefer to mate with males that provide higher levels of parental care. We manipulated male behavior using (1) different
nest sizes and (2) an application of low-O2 water in the nests, and found that females consistently preferred males with elevated levels of care in dichotomous mate
choice tests. This complements our earlier study in which we showed that males increase the amount and quality of care they
provide in the presence of females. Our results demonstrate that male care may have evolved as a result of sexual selection
rather than natural selection alone, and furthermore, that male care may not necessarily be in conflict with mate attraction. 相似文献
147.
Jae C. Choe 《Behavioral ecology and sociobiology》1994,34(4):233-237
Body size is clearly an important factor influencing the outcome of agonistic contests, but is often weakly correlated with dominance ranks in Zorotypus gurneyi Choe (Insecta: Zoraptera). The study of the development and dynamics of dominance relations using artificially constructed colonies show that age, or tenure within the colony, is the prime determinant of dominance among males. Dominance hierarchies become relatively stable within 2 or 3 days and males that emerge later normally begin at the bottom of the hierarchy regardless of size. Males interact much more frequently when they are simultaneously introduced to each other than when they are allowed to emerge at different times. In the latter case, males that emerge late appear to recognize relative dominance of older males and avoid direct contests. Considering the high correlation between dominance rank and mating success, there is a strong selective advantage to males that emerge earlier and such pressure of sexual selection may be responsible for the difference in life history strategies between Z. gurneyi and its sympatric congener, Z. barberi Gurney, in central Panama. 相似文献
148.
采用多种调查技术与方法 ,对尚勇自然保护区周边地区社会经济现状进行分析。该区存在群众文化素质偏低 ,医疗卫生状况较差 ,农业生产方式落后 ,保护区管理缺乏群众参与 ,保护区管理部门与周边乡村关系不够融洽等问题。针对这些问题 ,相应地提出了社区社会经济可持续发展的一系列对策 相似文献
149.
通过现场采样和过程模型模拟等方法研究了典型退役工业固废填埋场地(DISWL)原位开发条件下的健康风险及长期演化规律.结果表明,经过近20a的浸出和降解,86%的废物浸出浓度依然处于有害水平,70%的废物不宜直接作为建设用地土壤.直接作为建筑用地开发利用条件下,由于DISWL的性能退化会导致有害组分的浸出和渗漏增加,由此导致地下水水质超标概率经历从无(短期)到有(中期,个别物质如总氰化物T-CN和易释放氰化物F-CN),再到后期的较大概率超标(T-CN和F-CN)的渐变过程;同时,场地利用过程的健康风险也逐步增加,来自于As的致癌风险和自于T-CN的非致癌风险,分别超过风险可接受水平的81~179倍和55.32~224.3倍.上述结果提示DISWL场地开发再利用的风险评估和管控策略应重点考虑长期风险.对于长期风险不可接受的场地,通过降低废物中毒性物质的浸出浓度可实现长期风险可接受,并提出了相应浸出浓度限值的计算框架和方法. 相似文献
150.
Giuseppe Donati An Bollen Silvana M. Borgognini-Tarli Joerg U. Ganzhorn 《Behavioral ecology and sociobiology》2007,61(8):1237-1251
Animals show specific morphological, physiological and behavioural adaptations to diurnal or nocturnal activity. Cathemeral
species, i.e. animals with activities distributed over the 24-h period, have to compromise between these specific adaptations.
The driving evolutionary forces and the proximate costs and benefits of cathemerality are still poorly understood. Our goal
was to evaluate the role of predator avoidance, food availability and diet quality in shaping cathemeral activity of arboreal
mammals using a lemur species as an example. For this, two groups of collared lemurs, Eulemur collaris, were studied for 14 months in the littoral forest of southeastern Madagascar. Data on feeding behaviour were collected during
all-day and all-night follows by direct observation. A phenological transect containing 78 plant species was established and
monitored every 2 weeks to evaluate food availability during the study period. Characteristics of food items and animal nutritional
intake were determined via biochemical analyses. The ratio of diurnal to nocturnal feeding was used as response variable in
the analyses. The effects of abiotic environmental variables were removed statistically before the analyses of the biotic
variables. We found that diurnal feeding lasted longer during the hot–wet season (December–February), whereas nocturnal feeding
peaked during the hot–dry and cool–wet seasons (March–August). Although the lemurs foraged mostly in lower forest strata during
daylight and used emergent trees preferably at night, the variables which measured animal exposure to birds of prey failed
to predict the variation of the ratio of diurnal/nocturnal feeding. Ripe fruit availability and fiber intake are the two variables
which best predicted the annual variation of the lemur diurnality. The data indicate that feeding over the whole 24-h cycle
is advantageous during lean periods when animals have a fibre-rich, low-quality diet. 相似文献