首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   931篇
  免费   24篇
  国内免费   69篇
安全科学   28篇
废物处理   9篇
环保管理   288篇
综合类   289篇
基础理论   174篇
污染及防治   27篇
评价与监测   26篇
社会与环境   144篇
灾害及防治   39篇
  2024年   2篇
  2023年   12篇
  2022年   12篇
  2021年   11篇
  2020年   9篇
  2019年   20篇
  2018年   15篇
  2017年   18篇
  2016年   24篇
  2015年   25篇
  2014年   28篇
  2013年   73篇
  2012年   36篇
  2011年   49篇
  2010年   43篇
  2009年   37篇
  2008年   29篇
  2007年   47篇
  2006年   39篇
  2005年   49篇
  2004年   46篇
  2003年   53篇
  2002年   34篇
  2001年   46篇
  2000年   44篇
  1999年   40篇
  1998年   24篇
  1997年   30篇
  1996年   30篇
  1995年   22篇
  1994年   12篇
  1993年   15篇
  1992年   11篇
  1991年   9篇
  1990年   6篇
  1989年   2篇
  1988年   6篇
  1987年   1篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1980年   4篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有1024条查询结果,搜索用时 218 毫秒
991.
张力 《环境科学与管理》2011,36(10):41-42,40
低碳农业是生物多样性农业,总结了黑龙江省构建低碳农业的必要性,介绍了低碳农业发展存在的问题,提出了今后黑龙江省构建低碳农业的对策。  相似文献   
992.
湖北省2008年初低温雨雪冰冻灾害特点及影响分析   总被引:10,自引:1,他引:10  
008年初,湖北省出现了自1954/1955年冬季以来最严重的低温雨雪冰冻灾害,直接经济损失高达110亿元以上,分析评估此次灾害的基本特点及对各行各业的影响,可为今后抗御类似灾害提供依据。结果表明:①此次灾害影响范围广,受灾人数多,损失重,第三、四场雪使危害迅速加剧,后续效应强、时间长;②影响行业可分为交通、电网及供电系统、通讯、农业、林业、企业和市政设施、居民生活、湖泊结冰等8大类,并可细分为24小类,涉及社会和人们生活的众多方面,足见影响面之广,危害之重;③影响因子以低温、冰冻(道路结冰、电线覆冰)、雪压等为主,另外还有大风、雪雾、湖泊封冻、冰雪融化等;④由于降雪及低温持续时间长、雪量大,对农林业危害严重;由于电力、〖JP2〗通讯、建筑设施以及道路结冰严重,对电网、电力供应、交通安全以及社会公众生产、生活等造成极大的影响。〖  相似文献   
993.
Soil management practices for sustainable agro-ecosystems   总被引:1,自引:0,他引:1  
A doubling of the global food demand projected for the next 50 years poses a huge challenge for the sustainability of both food production and global and local environments. Today’s agricultural technologies may be increasing productivity to meet world food demand, but they may also be threatening agricultural ecosystems. For the global environment, agricultural systems provide both sources and sinks of greenhouse gases (GHGs), which include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). This paper addresses the importance of soil organic carbon (SOC) for agro-ecosystems and GHG uptake and emission in agriculture, especially SOC changes associated with soil management. Soil management strategies have great potential to contribute to carbon sequestration, since the carbon sink capacity of the world’s agricultural and degraded soil is 50–66% of the historic carbon loss of 42–72 Pg (1 Pg=1015 g), although the actual carbon storage in cultivated soil may be smaller if climate changes lead to increasing mineralization. The importance of SOC in agricultural soil is, however, not controversial, as SOC helps to sustain soil fertility and conserve soil and water quality, and organic carbon compounds play a variety of roles in the nutrient, water, and biological cycles. No-tillage practices, cover crop management, and manure application are recommended to enhance SOC storage and to contribute to sustainable food production, which also improves soil quality. SOC sequestration could be increased at the expense of increasing the amount of non-CO2 GHG emissions; however, soil testing, synchronized fertilization techniques, and optimum water control for flooding paddy fields, among other things, can reduce these emissions. Since increasing SOC may also be able to mitigate some local environmental problems, it will be necessary to have integrated soil management practices that are compatible with increasing SOM management and controlling soil residual nutrients. Cover crops would be a critical tool for sustainable soil management because they can scavenge soil residual nitrogen and their ecological functions can be utilized to establish an optimal nitrogen cycle. In addition to developing soil management strategies for sustainable agro-ecosystems, some political and social approaches will be needed, based on a common understanding that soil and agro-ecosystems are essential for a sustainable society.  相似文献   
994.
长江流域农业用水效率研究:基于超效率DEA和Tobit模型   总被引:4,自引:0,他引:4  
提高农业用水效率对于农业可持续发展和保障粮食安全具有重大意义。考虑降雨量中绿水资源对农作物生长的重要性,将绿水资源纳入农业用水总量,全面分析长江流域农业用水效率变动趋势。基于1998~2011年长江流域10个省份的面板数据,运用超效率DEA和Tobit模型对流域农业用水效率进行了测度和影响因素的检验。研究发现:(1)在研究期间内,长江流域农业用水效率呈现出波段式上升态势;流域各区段的用水效率呈下游、上游、中游依次递减的区域分布格局。(2)灌溉费、节水灌溉技术和农业对外开放度对流域农业用水效率有显著的正向效应;人均水资源量和年降水量均对流域农业用水效率有负向关系,但只有降水量在统计上显著。研究结果表明应当提高长江流域,尤其是中上游水资源禀赋较高地区的农业用水效率;在农业节水的具体政策方面,调整农业灌溉水价、加强农业技术创新能力和扩大农业经济对外开放程度能够取得较为显著的节水效应。  相似文献   
995.
The two‐stage ditch is a novel management practice originally implemented to increase bank stability through floodplain restoration in channelized agricultural streams. To determine the effects of two‐stage construction on sediment and nutrient loads, we monitored turbidity, and also measured total suspended solids (TSS), dissolved inorganic nitrogen (N) species, and phosphorus (P) after two‐stage ditch construction in reference and manipulated reaches of four streams. Turbidity decreased during floodplain inundation at all sites, but TSS and P, soluble reactive phosphorus (SRP) and total phosphorus (TP) decreased only in the two‐stage ditches with longer duration of inundation. Both TSS and TP were positively correlated within individual streams, but neither were correlated with turbidity. Phosphorus was elevated in the stream to which manure was applied adjacent to the two‐stage reach, but not the reference reach, suggesting that landscape nutrient management plans could restrict nutrient transport to the stream, ultimately determining the efficacy of instream management practices. In addition, ammonium and nitrate decreased in two‐stage reaches with lower initial N concentrations. Overall, results suggest that turbidity, TSS, and TP were reduced during floodplain inundation, but the two‐stage alone may not be effective for managing high inorganic N loads.  相似文献   
996.
Public trust in organizations focused on improving environmental quality is important for increasing awareness and changing behaviors that have water quality implications. Few studies have addressed trust in soil and water quality information sources, particularly for both agricultural and nonagricultural respondents of the same watersheds. Surveys in 19 watersheds across five states in the Midwest assessed trust in, and familiarity with, soil and water quality information sources. Overall, respondents most trusted University Extension, Soil and Water Conservation Districts, and the Natural Resource Conservation Service, while lawn care companies, environmental groups, and land trusts were less trusted. Significant differences in trusted sources were found between watersheds, and between agricultural and nonagricultural respondents across and within watersheds. Among agricultural respondents, a clear relationship exists between familiarity and trust; as familiarity with an organization increases, so too does level of trust. This relationship is less clear‐cut for nonagricultural respondents in this region. We highlight implications of these findings for soil and water quality outreach efforts.  相似文献   
997.
美丽中国建设需要各地区各部门社会各界共同推动,开展美丽中国建设地方实践是实现美丽中国建设目标的有效途径。党的十八大以来,全国各地积极开展美丽中国建设实践,全力打造美丽中国建设样本和先行区,丰富建设内涵、深化建设内容、拓展建设领域、创新实践模式、完善实践机制,取得了显著成效,形成了一批典型经验。进入新时代新征程,围绕建设人与自然和谐共生的美丽中国,需要进一步发挥各地积极性、主动性、创造性,深化美丽中国建设地方实践,坚持分区分类因地制宜,形成各美其美的美丽中国建设格局,坚持系统谋划,创新提升美丽中国建设地方实践模式,强化政策协同和宣传激励,形成各地区全社会合力共建美丽中国的良好氛围,为全面建设美丽中国提供丰富的地方实践和坚实的基础支撑。  相似文献   
998.
胶州市农村生态环境保护的对策及建议   总被引:1,自引:0,他引:1  
在对胶州市农村生态环境保护工作进行调查研究的基础上,分析了胶州市农村生态环境保护现状和污染来源,以及农村环保工作存在的环境意识差、管理混乱、环境治理资金不足等主要问题。同时结合胶州农村生态环境保护现状,提出了编制农村生态规划、加强基础设施建设、建设生态农业、实行农业清洁生产等解决胶州市农村生态环境保护工作的对策和建议。  相似文献   
999.
刘成玉 《四川环境》2010,29(2):84-88
以高投入、高消耗、高产出和高排放为特征的都市现代农业,对环境具有更大、更直接的影响,但只要选择恰当的模式,都市现代农业能够与环境实现协调发展。本文总结了成都市几种环境友好型现代农业发展模式,提出了促进环境与现代农业进一步协调的途径与对策,对全国的都市农业的发展有参考价值。  相似文献   
1000.
通过制作多媒体课件,探讨提高《电机拖动基础》课程教学效果的尝试及现代化教学手段对教学影响的重要性、必要性和实际运用中需要注意的问题。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号