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   3848篇
  免费   12篇
  国内免费   66篇
安全科学   106篇
废物处理   223篇
环保管理   386篇
综合类   472篇
基础理论   1240篇
环境理论   1篇
污染及防治   940篇
评价与监测   327篇
社会与环境   221篇
灾害及防治   10篇
  2023年   27篇
  2022年   133篇
  2021年   106篇
  2020年   42篇
  2019年   46篇
  2018年   169篇
  2017年   180篇
  2016年   239篇
  2015年   77篇
  2014年   54篇
  2013年   144篇
  2012年   465篇
  2011年   261篇
  2010年   65篇
  2009年   57篇
  2008年   71篇
  2007年   90篇
  2006年   86篇
  2005年   403篇
  2004年   543篇
  2003年   412篇
  2002年   50篇
  2001年   46篇
  2000年   26篇
  1999年   35篇
  1998年   5篇
  1997年   11篇
  1996年   4篇
  1995年   15篇
  1994年   9篇
  1993年   3篇
  1992年   5篇
  1991年   8篇
  1990年   5篇
  1989年   5篇
  1988年   2篇
  1985年   3篇
  1975年   2篇
  1974年   3篇
  1972年   2篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
  1964年   1篇
  1961年   1篇
  1959年   1篇
  1957年   1篇
排序方式: 共有3926条查询结果,搜索用时 15 毫秒
81.
In temperate climates, the initiation and termination of diapause synchronize the stress-tolerant stage with the stressful season and reproduction with the non-stressful season in many insects. Synchronization is often regulated by photoperiodism.Voltinism and the ultimate size of adults are also important determinants for their lifecycle, and different diapause stages and voltinism patterns are known in crickets.Here, we investigated the life history of the African cricket Gryllus argenteus from Malawi, which is a typical arid tropical highland. The climate is characterized by alternating arid and wet seasons, each of which lasts for half a year, and where the available heat mass is much less than lowlands at the same latitude. We first measured the nymphal duration at each rearing temperature and calculated the lower developmental threshold (t 0) to be 20.19 °C based on Ikemoto and Takai (2000) and 19.38 °C based on a conventional line-fitting method. These values are very high relative to many other insects. The local temperature in winter does not fall below 15 °C, but this is much higher than the lethal limit. This suggested that critical stress in this locality was not coldness but low precipitation in winter. We estimated, based both on local temperature change and the Ikemoto and Takai’s t 0, that G. argenteus required 3 years to complete its lifecycle unlike wet lowland species, where univoltinism or multi-voltinism are commonplace. Photoperiodism was observed in this species, but due to a lag between annual cycles in photoperiod, temperature, and humidity, photoperiodism alone cannot atune their lifecycle with local conditions.Synchronization in this species was achieved by three different adaptations: photoperiodism, high t 0, and large body size, which give it a long lifecycle. Although the species cannot achieve a univoltine lifecycle because of its high t0 value, it can escape from dry season by entering diapause at moderate temperatures, probably thereby achieving adaptive synchrony of lifecycle with both favorable and unfavorable seasons. A comparison between a conventional photothermogram and a newly formulated photohydrogram or photohygrogram demonstrates that even though sufficient heat is available, scarcity of water and thus scarcity of foliage should force the cricket to maintain diapause at intermediate temperature. The results suggested that high t 0, large body size, and multi-ennial lifecycle mutually affect each other and formulate a unique adaptation under such an extreme environment.  相似文献   
82.
Journal of Material Cycles and Waste Management - In this study, utilization of waste fluorescent lamp as mineral filler in asphalt mixture was investigated. The phosphorus powder of fluorescent...  相似文献   
83.
Environment, Development and Sustainability - The current study explores the role of green trust, green perceived risk and green perceived quality in changing green purchase intention....  相似文献   
84.

Climate change influences the agricultural sector by reducing available water resources, thereby influencing income, consumer and producer surplus, and crop prices. So, it is necessary to have a comprehensive integrated method to measure the effects of these changes on natural resources and social conditions. The present study aims to use the positive mathematical programming method to discover the trend and conditions of groundwater resources, agricultural water use, food security, and economic welfare of the agricultural sector in Iran. To this end, data for the period 2000–2015 was used under four different scenarios of normal climate change, climate change, climate variability, and concurrent climate change The results showed that the mean agricultural water use will amount to 35,103.6, 26,533.8, 35,216, and 26,510.7 million m3 and the mean decline in the reserves of aquifers will amount to 4422.22, 11,165.6, 4438.25, and 11,267.4 million m3 under the scenarios, respectively. With respect to food security, the net farm revenue will be 314,560, 248,753, 315,427, and 248,574 billion IRR, respectively. The mean crop price per ton will reach 905.3, 1141.8, 904, and 1142.8 million IRR, respectively. The mean consumer surplus will be 172,107.7, 166,450, 172,024, and 166,403 billion IRR and the mean producer surplus will be 419,959.2, 395,380, 419,751, and 395,204 billion IRR, respectively. Based on the results, to reduce the adverse impacts of climate change on different studied aspects, it is necessary to change policymaking in the water and agricultural sectors, especially regarding the shift from traditional agricultural water allocation to its market-based allocation and to change planting pattern.

  相似文献   
85.
Environmental Economics and Policy Studies - While the EU is working toward the implementation of the world’s first Carbon Border Adjustment (CBA) Mechanism, a gap remains between the ways in...  相似文献   
86.
Promoting shared leadership in teams and enhancing team creativity is aided by complementarity between leader and team member characteristics. We integrate insights from social learning theory and dominance complementarity perspective with the team leadership and creativity literature to explore the facilitating role of formal participative leadership for enhancing team creativity indirectly by promoting shared leadership. The relationships among formal participative leadership, shared leadership, and team creativity are bounded by team voice behavior and team creative efficacy. To test our theoretical model, we collected multisource and multiwave survey data from 382 members of 73 teams. Results revealed a significant positive relationship of participative leadership with shared leadership in teams, which in turn was positively associated with team creativity. Team voice behavior and team creative efficacy moderated these relationships, respectively, by strengthening the positive relationships. We discuss the theoretical contributions, practical implications, and future directions of our findings.  相似文献   
87.
Environmental Science and Pollution Research - Substantial discharge of hazardous substances, especially dyes and heavy metal ions to the environment, has become a global concern due to...  相似文献   
88.
Environmental Science and Pollution Research - Mapping land cover changes (LCC) cover three decades over North and West Africa regions provides critical insights for the climate research that...  相似文献   
89.

Using association of plants, nanomaterials, and plant growth-promoting bacteria (PGPR) is a novel approach in remediation of heavy metal-contaminated soils. Co-application of nanoscale zerovalent iron (nZVI) and PGPR to promote phytoremediation of Sb-contaminated soil was investigated in this study. Seedlings of Trifolium repens were exposed to different regimes of nZVI (0, 150, 300, 500, and 1000 mg/kg) and the PGPR, separately and in combination, to investigate the effects on plant growth, Sb uptake, and accumulation and physiological response of the plant in contaminated soil. Co-application of nZVI and PGPR had positive effects on plant establishment and growth in contaminated soil. Greater accumulation of Sb in the shoots compared to the roots of T. repens was observed in all treatments. Using nZVI significantly increased accumulation capacity of T. repens for Sb with the greatest accumulation capacity of 3896.4 μg per pot gained in the “PGPR+500 mg/kg nZVI” treatment. Adverse impacts of using 1000 mg/kg nZVI were found on plant growth and phytoremediation performance. Significant beneficial effect of integrated use of nZVI and PGPR on plant photosynthesis was detected. Co-application of nZVI and PGPR could reduce the required amounts of nZVI for successful phytoremediation of metalloid polluted soils. Intelligent uses of plants in accompany with nanomaterials and PGPR have great application prospects in removal of antimony from soil.

  相似文献   
90.
Environmental Science and Pollution Research - Antioxidant enzymes such as glutathione S-transferases (GSTs) and cytochromes P450 (CYPs) are involved in the metabolism and detoxification of...  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