全文获取类型
收费全文 | 1813篇 |
免费 | 199篇 |
国内免费 | 227篇 |
专业分类
安全科学 | 536篇 |
废物处理 | 141篇 |
环保管理 | 267篇 |
综合类 | 673篇 |
基础理论 | 321篇 |
环境理论 | 2篇 |
污染及防治 | 94篇 |
评价与监测 | 17篇 |
社会与环境 | 126篇 |
灾害及防治 | 62篇 |
出版年
2024年 | 3篇 |
2023年 | 39篇 |
2022年 | 65篇 |
2021年 | 83篇 |
2020年 | 89篇 |
2019年 | 94篇 |
2018年 | 62篇 |
2017年 | 80篇 |
2016年 | 99篇 |
2015年 | 72篇 |
2014年 | 114篇 |
2013年 | 132篇 |
2012年 | 163篇 |
2011年 | 133篇 |
2010年 | 100篇 |
2009年 | 120篇 |
2008年 | 132篇 |
2007年 | 110篇 |
2006年 | 96篇 |
2005年 | 79篇 |
2004年 | 77篇 |
2003年 | 66篇 |
2002年 | 34篇 |
2001年 | 36篇 |
2000年 | 30篇 |
1999年 | 17篇 |
1998年 | 23篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有2239条查询结果,搜索用时 25 毫秒
991.
We investigated the effects of ambient ultraviolet (UV) radiation on (i) the performance and chemistry of soybean plants, (ii) the performance of Spodoptera frugiperda and (iii) the foraging behavior of the herbivore's natural enemy Cotesia marginiventris which exploits herbivore-induced plant volatiles (VOC) for host location. The accumulation of protective phenolics was faster in plants receiving ambient UV than in controls exposed to sun light lacking UV. Accordingly, isorhamnetin- and quercetin-based flavonoids were increased in UV exposed plants. No UV effects were found on the performance and feeding behavior of S. frugiperda. Herbivore-damaged plants emitted the same VOC when grown under ambient or attenuated UV for 5, 10 or 30 days. Consequently, C. marginiventris was attracted but did not discriminate between exposed and unexposed soybeans. In summary, ambient UV radiation affected soybean morphology and physiology but did not destabilize interactions between trophic levels. 相似文献
992.
向锋 《生态与农村环境学报》1998,(3)
在农药的环境行为研究中,常用一级动力学反应方程来模拟农药的降解或残留。本文论述了用线性回归分析法估计一级化学动力学方程参数时存在的初始浓度飘移和非本义最优化问题,讨论了与此相关联的试验设置、安全间隔期、分段模拟和试验数据处理等问题,提出了解决问题的初步设想。 相似文献
993.
994.
Effects of incubation temperature on hatchling pine snakes: implications for survival 总被引:2,自引:0,他引:2
Joanna Burger 《Behavioral ecology and sociobiology》1998,43(1):11-18
Incubation temperature in ectothermic vertebrates affects incubation periods, and in some reptiles it affects sex ratios
and behavior. I present evidence that incubation temperature affects emergence and post-hatching behavior of pine snakes (Pituophis melanoleucus) that could influence survival in the weeks before hibernation. Hatchlings incubated at low temperatures remained in the
nest longer, had fewer alternate nest openings, and fewer underground tunnels to hide in than did hatchlings from warmer temperatures.
These conditions could render hatchlings from low-temperature nests more vulnerable to predation because, if a nest is opened,
they are not inside tunnels where they would be protected. Hatchlings from nests incubated at low temperatures took longer
to find shade during a thermoregulation test, and were less likely to move about in search of other cover than were those
from higher-incubation-temperature artificial nests. Similarly, hatchlings from nests with low incubation temperatures were
less responsive to a predatory stimulus and had a longer latency to strike than other hatchlings. Taken together, hatchlings
from nests with low incubation temperatures might be less able to avoid predators and find shade than those from nests incubated
at higher temperatures, and thus could be expected to have lower survival in nature.
Received: 21 July 1997 / Accepted after revision: 15 February 1998 相似文献
995.
Diana Stuart 《Journal of Agricultural and Environmental Ethics》2009,22(1):53-71
As environmental and conservation efforts increasingly turn towards agricultural landscapes, it is important to understand
how land management decisions are made by agricultural producers. While previous studies have explored producer decision-making,
many fail to recognize the importance of external structural influences. This paper uses a case study to explore how consolidated
markets and increasing corporate power in the food system can constrain producer choice and create ethical dilemmas over land
management. Crop growers in the Central Coast region of California face conflicting demands regarding environmental quality
and industry imposed food safety standards. A mail survey and personal interviews were used to explore growers’ perceptions
and actions regarding these demands. Results indicate that in many cases growers face serious ethical dilemmas and feel pressured
by large processing and retail firms to adopt measures they find environmentally destructive and unethical. Future strategies
to address environmental issues on agricultural landscapes should consider the economic constraints producers face and the
role of large firms in creating production standards. 相似文献
996.
With the use of water approaching, and in some cases exceeding, the limits of sustainability in many locations, there is an increasing recognition of the need to utilise stormwater for non-potable requirements, thus reducing the demand on potable sources. This paper presents a review of Australian stormwater treatment and recycling practices as well as a discussion of key lessons and identified knowledge gaps. Where possible, recommendations for overcoming these knowledge gaps are given. The review of existing stormwater recycling systems focussed primarily on the recycling of general urban runoff (runoff generated from all urban surfaces) for non-potable purposes. Regulations and guidelines specific to stormwater recycling need to be developed to facilitate effective design of such systems, and to minimise risks of failure. There is a clear need for the development of innovative techniques for the collection, treatment and storage of stormwater. Existing stormwater recycling practice is far ahead of research, in that there are no technologies designed specifically for stormwater recycling. Instead, technologies designed for general stormwater pollution control are frequently utilised, which do not guarantee the necessary reliability of treatment. Performance modelling for evaluation purposes also needs further research, so that industry can objectively assess alternative approaches. Just as many aspects of these issues may have impeded adoption of stormwater, another impediment to adoption has been the lack of a practical and widely accepted method for assessing the many financial, social and ecological costs and benefits of stormwater recycling projects against traditional alternatives. Such triple-bottom-line assessment methodologies need to be trialled on stormwater recycling projects. If the costs and benefits of recycling systems can be shown to compare favourably with the costs and benefits of conventional practices this will provide an incentive to overcome other obstacles to widespread adoption of stormwater recycling. 相似文献
997.
Correlated evolution of prey chemical discrimination with foraging, lingual morphology and vomeronasal chemoreceptor abundance in lizards 总被引:3,自引:0,他引:3
William E. Cooper 《Behavioral ecology and sociobiology》1997,41(4):257-265
Comparative data from ten families of lizards suggest that correlated evolution has occurred between the ability to identify
prey chemicals and several aspects of lingual function and morphology, abundance of vomeronasal chemoreceptor cells, and foraging
behavior. Ability to discriminate prey chemicals from control substances was measured experimentally and correlated with other
variables by Felsenstein's method. This ability increased with evolutionary increases in degree of lingual protrusion during
tongue-flicking, which may reflect the tongue's ability to reach substrates to be sampled. It increased with deepened lingual
forking and greater lingual elongation, which may be important for scent-trailing and sampling ability, respectively. Discriminatory
ability also increased with abundance of vomerolfactory chemoreceptors, which presumably reflects some aspects of analytical
capacities of the vomeronasal system. Prey chemical discrimination increased with degree of active foraging. Natural selection
for improved vomerolfactory sampling and analysis of prey chemicals by active, but not ambush, foragers appears to account
for the observed relationships. In active foragers that use vomerolfaction to locate prey, natural selection favors increased
abilities to lingually sample chemicals from environmental substrates, analyze the samples for prey chemicals, and respond
appropriately if prey chemicals or possible prey chemicals are detected. Such selection can account for the observed relationships
among the sampling device and its movements, the sense, the discriminations, and variations in foraging ecology.
Received: 13 February 1997 / Accepted after revision: 12 June 1997 相似文献
998.
长江八里江江段江豚种群数量、行为及其活动规律与保护 总被引:13,自引:0,他引:13
1989-1999年,在长江八里江江段对江豚进行了28次往返观察和8次定点观察。结果表明,近10年八里江江段江豚种群数量遥感量逐年呈明显递减趋势,平均每年以7.3%速率递减;1996年后,枯水季节江豚不再进行江一湖迁移,其活动范围仅限于约20km长的八里江江口上下江段,较1993年以前缩短了约40km。江豚在八里江江段的行为多种多样,通过对江豚种群在八里江江段的集群、摄食、逃避、发情与交配、抚幼、歇息和玩耍行为的描述、比较和分析,认为长江八里江江段是江豚典型的摄食和抚幼场所,同时也是江豚大规模集群的适宜栖居地。提出了加强八里江江段江豚种群常年监测的必要性,并对八里江江段江豚种群的就地保护提出了建议。 相似文献
999.
城市地震时人的心理反应与应急对策 总被引:8,自引:2,他引:6
本文运用社会心理学、社会行为学与地震社会学的原理,分析研究城市地震灾害发生时,人们的心理行为反应特征以及制约震时人们心理行为反应的主客观因素,在此基础上提出震时人们应采取的应急对策。 相似文献
1000.
推行中水回用技术问题探讨 总被引:6,自引:0,他引:6
中水回用在我国刚起步,政府应尽快制订出相应的标准和措施,大力提倡、鼓励各企、事业单位开展中水回用,以降低城镇供水压力和用水成本支出,节约水资源. 相似文献