全文获取类型
收费全文 | 8179篇 |
免费 | 551篇 |
国内免费 | 2220篇 |
专业分类
安全科学 | 806篇 |
废物处理 | 869篇 |
环保管理 | 1179篇 |
综合类 | 5522篇 |
基础理论 | 667篇 |
环境理论 | 1篇 |
污染及防治 | 1574篇 |
评价与监测 | 233篇 |
社会与环境 | 55篇 |
灾害及防治 | 44篇 |
出版年
2024年 | 17篇 |
2023年 | 116篇 |
2022年 | 171篇 |
2021年 | 220篇 |
2020年 | 229篇 |
2019年 | 195篇 |
2018年 | 172篇 |
2017年 | 186篇 |
2016年 | 255篇 |
2015年 | 263篇 |
2014年 | 470篇 |
2013年 | 558篇 |
2012年 | 637篇 |
2011年 | 556篇 |
2010年 | 484篇 |
2009年 | 523篇 |
2008年 | 452篇 |
2007年 | 761篇 |
2006年 | 815篇 |
2005年 | 591篇 |
2004年 | 468篇 |
2003年 | 479篇 |
2002年 | 399篇 |
2001年 | 362篇 |
2000年 | 312篇 |
1999年 | 335篇 |
1998年 | 219篇 |
1997年 | 159篇 |
1996年 | 114篇 |
1995年 | 122篇 |
1994年 | 94篇 |
1993年 | 73篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 13篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Crop damage is the most common impact of negative interactions between people and elephants and poses a significant threat to rural livelihoods and conservation efforts. Numerous approaches to mitigate and prevent crop damage have been implemented throughout Africa and Asia. Despite the documented high efficacy of many approaches, losses remain common, and in many areas, damage is intensifying. We examined the literature on effectiveness of crop-damage-mitigation strategies and identified key gaps in evaluations. We determined there is a need to better understand existing solutions within affected communities and to extend evaluations of effectiveness beyond measurement of efficacy to include rates of and barriers to adoption. We devised a conceptual framework for evaluating effectiveness that incorporates the need for increased emphasis on adoption and can be used to inform the design of future crop-damage mitigation assessments for elephants and conflict species more widely. The ability to prevent crop loss in practice is affected by both the efficacy of a given approach and rates of uptake among target users. We identified the primary factors that influence uptake as local attitudes, sustainability, and scalability and examined each of these factors in detail. We argue that even moderately efficacious interventions may make significant progress in preventing damage if widely employed and recommend that wherever possible scientists and practitioners engage with communities to build on and strengthen existing solutions and expertise. When new approaches are required, they should align with local attitudes and fit within limitations on labor, financial requirements, and technical capacity. 相似文献
2.
Joachim Ruther 《Chemoecology》2004,14(3-4):187-192
Summary. Field tests were performed to evaluate the
response of the garden chafer, Phyllopertha horticola
(Coleoptera: Scarabaeidae) to known scarab attractants and to
investigate the influence of trap colour and height on the
number of captured beetles. Both sexes were attracted by a
lure mixture composed of geraniol, eugenol, and 2-phenylethyl
propionate (PEP) (ratio 3:7:3). When testing floral volatiles
individually, only geraniol, eugenol and methyl anthranilate
but not PEP was attractive. Response of garden chafer to (Z)-
3-hexen-1-ol was strongly male-biassed. Both the response
to floral volatiles and (Z)-3-hexen-1-ol was increased by
using funnel traps with yellow instead of grey vanes. Traps
positioned at 50 and 125 cm above ground captured significantly
more garden chafers than those at 200 cm. The
strongly male-biassed response to (Z)-3-hexen-1-ol suggests
that in P. horticola (subfamily Rutelinae) orientation towards plant volatiles emitted upon mechanical damage of plants is
part of the male mate finding strategy as recently demonstrated
for cockchafers of the genus Melolontha (subfamily Melolonthinae). Possible application of plant volatiles for
control of P. horticola is discussed. 相似文献
3.
4.
5.
对石油亚砜(PSO)萃取巯基醋酸的条件和影响进行了实验研究,确定了石油亚砜通过氢键和巯基醋酸形成的萃合物的组成.为从废水中回收巯基醋酸以及石油硫醚的综合利用提供了依据. 相似文献
6.
7.
8.
9.
生活垃圾生物处理的研究与展望 总被引:2,自引:0,他引:2
综述了国内外生活垃圾生物处理的研究进展和目前生活垃圾微生物研究水平,以及生活垃圾处理发展趋势与新动向,在此基础上提出了生活垃圾处理的建议和展望。 相似文献
10.
SO2 和氟化物对农作物的危害可通过症状、镜检和受害叶片的化学分析来鉴别 ,并从风向、与污染源距离、障碍物和叶片成熟程度几方面与作物病虫等影响因素相区别。排放浓度、接触时和作物本身抗性是影响危害程度的主要因素。应从治理污染、选种抗性强树木、避开作物敏感生育期、合理种植、加强施肥等方面采取措施加以防治 相似文献