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   289篇
  免费   1篇
  国内免费   9篇
安全科学   6篇
废物处理   65篇
环保管理   11篇
综合类   43篇
基础理论   60篇
污染及防治   88篇
评价与监测   12篇
社会与环境   12篇
灾害及防治   2篇
  2023年   2篇
  2022年   4篇
  2021年   4篇
  2020年   2篇
  2019年   1篇
  2018年   10篇
  2017年   5篇
  2016年   7篇
  2015年   8篇
  2014年   10篇
  2013年   20篇
  2012年   7篇
  2011年   19篇
  2010年   7篇
  2009年   27篇
  2008年   17篇
  2007年   21篇
  2006年   21篇
  2005年   18篇
  2004年   19篇
  2003年   18篇
  2002年   5篇
  2001年   7篇
  2000年   3篇
  1999年   4篇
  1998年   1篇
  1997年   6篇
  1996年   2篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1989年   2篇
  1987年   1篇
  1984年   3篇
  1982年   1篇
  1977年   1篇
  1976年   1篇
  1973年   1篇
  1972年   1篇
  1969年   1篇
  1968年   1篇
  1965年   1篇
  1961年   1篇
排序方式: 共有299条查询结果,搜索用时 718 毫秒
101.
To suppress the coagulation of humic acid (HA) in aqueous solutions, HA was modified with hydrophilic amines, such as glucosamine or taurine. These amines were attached to carboxyl groups in HA via amide bond formation. The degree of modification (R(m)) was estimated to be 21-38%. Infrared spectra of the modified HAs were also consistent with the presence of amide bonds. Acid-base titration showed that the average acid-dissociation constant (pK(app)) of the HA samples was increased by the modification. The Ca(2+) binding capacity of HA decreased with an increase in R(m) value. Critical pH or Ca(2+) concentration, at which HA coagulation occurs, was increased as the result of the modification. These critical points for taurine-HA were higher than those for glucosamine-HA. This is mainly due to electrostatic repulsion by sulfonate groups in taurine. These results indicate that the coagulation of HA is suppressed by modifying the molecules with glucosamine or taurine.  相似文献   
102.
China has been the largest importer of secondary materials for recycling from Japan during the past decade. In this study, we analyzed the transfer of major secondary materials (plastic, steel, copper, and aluminum scrap) from Japan to China. We identified specific destinations for secondary materials, and the characteristics of secondary materials transferred to China. The major destination for the transfer of secondary materials to China is Guangdong province and part of the Huadong area (Shanghai, Zhejiang, and Jiangsu). Most scrap metal imported into China is of low quality. The destinations of most high-quality nonferrous scrap, imported as processed goods on consignment or through the transit improvement trade, are the northeast border provinces, especially Xinjiang Uighur province. The coefficients of specialization for Chinese cities were different from those for the provinces. Guangdong shows an average recycling structure for China. The structure gradually changes from south to north.  相似文献   
103.
In Japan, the Law for the Recycling of Specified Kinds of Home Appliances came into effect in April 2001. This law aims to introduce appropriate waste treatment and promote the efficient use of resources so that we can achieve a sound material-cycle society. The law introduces a new framework for recycling that places obligations principally on the manufacturers and retailers of home appliances. Material flow analysis of this new framework is essential for evaluation of the system and for finding any problems that may exist. We therefore analyzed the material flows in facilities that recycle electrical home appliances. The mass balances in the recycling facilities were appropriately estimated. Then the potential destinations were surveyed and analyzed, even though the legal framework does not include flows after the recycling facilities. The potential destination after the facilities varies and depends on both the economy and the related regulations. Currently, considerable amounts of recovered materials are exported and recycled. However, the sustainability of these trades is unknown. Therefore, we should keep a close eye on the situation and make sure that our recycling system is adaptable to meet any future changes.  相似文献   
104.
Serious adverse impacts on the environment and human health from e-waste recycling have occurred in the past and continue to occur in China today, due to a lack of national management strategies. China has made great efforts to face the challenges of the approaching peak increase in the domestic generation of e-waste and the illegal shipment of e-waste from other countries. This study examined recent progress and analysed the main problems associated with this issue in China. It was found that the material and the financial flows of e-waste in China had their own specific characteristics. Nearly 60% of the generated e-wastes were sold to private individual collectors and passed into informal recycling processes. More than 90% of Chinese citizens are reluctant to pay for the recycling of their e-waste. This is due to their traditional understanding that there remained value in these end-of-life products. Regulations concerning e-waste in China have been drafted but their deficiencies are obvious. The extended producer responsibilities (EPR) have been introduced but are not well defined. Eight formal facilities have been planned and are under construction or are in operation along the eastern coast of China but it will be difficult for them to compete with the informal processes for the reasons identified during the study.  相似文献   
105.
The present study was conducted to analyze the ratification status of International Labour Organization (ILO) conventions related to occupational safety and health (OSH) by ILO member states in terms of national indicators (length of ILO membership and national income status) and regional affiliation. 17 conventions designated as OSH-related by the 2003 International Labour Conference were examined. In general, countries with longer ILO membership ratified higher numbers of conventions related to OSH. With some variation, long-membership countries had the largest number of ratifications, followed by middle- and short-membership countries in all regions. There were also incremental increases in the number of ratifications for OSH-related conventions according to the national income status. Common regional characteristics that could not be explained by the factors studied also existed. Future efforts to increase ratification at an international level will need to consider the factors influencing ratification practice among the member states.  相似文献   
106.
In the transport sector, few projects applied Clean Development Mechanism (CDM) or Joint Implementation (JI) projects. This study will examine the feasibility of applying CDM to the transport sector from viewpoints of validation of processes and funding. A number of greenhouse gas emission reduction projects, as well as traffic management project within existing transport infrastructures, can be implemented as CDM projects. New transport infrastructure projects can be validated by transportdemand forecasting and traffic simulation methods, though application of Life Cycle Assessment (LCA) and Intelligent Transport Systems (ITS) technologies. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
107.
108.
109.
Environmental Science and Pollution Research - This study evaluated the occurrence of PPCPs in Cau River (Vietnam). Surface water and sediment samples were collected to determine PPCP...  相似文献   
110.
In a previous article, Beschta et al. (Environ Manag 51(2):474–491, 2013) argue that grazing by large ungulates (both native and domestic) should be eliminated or greatly reduced on western public lands to reduce potential climate change impacts. The authors did not present a balanced synthesis of the scientific literature, and their publication is more of an opinion article. Their conclusions do not reflect the complexities associated with herbivore grazing. Because grazing is a complex ecological process, synthesis of the scientific literature can be a challenge. Legacy effects of uncontrolled grazing during the homestead era further complicate analysis of current grazing impacts. Interactions of climate change and grazing will depend on the specific situation. For example, increasing atmospheric CO2 and temperatures may increase accumulation of fine fuels (primarily grasses) and thus increase wildfire risk. Prescribed grazing by livestock is one of the few management tools available for reducing fine fuel accumulation. While there are certainly points on the landscape where herbivore impacts can be identified, there are also vast grazed areas where impacts are minimal. Broad scale reduction of domestic and wild herbivores to help native plant communities cope with climate change will be unnecessary because over the past 20–50 years land managers have actively sought to bring populations of native and domestic herbivores in balance with the potential of vegetation and soils. To cope with a changing climate, land managers will need access to all available vegetation management tools, including grazing.  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