全文获取类型
收费全文 | 1335篇 |
免费 | 60篇 |
国内免费 | 482篇 |
专业分类
安全科学 | 75篇 |
废物处理 | 80篇 |
环保管理 | 81篇 |
综合类 | 766篇 |
基础理论 | 223篇 |
污染及防治 | 526篇 |
评价与监测 | 48篇 |
社会与环境 | 45篇 |
灾害及防治 | 33篇 |
出版年
2023年 | 29篇 |
2022年 | 77篇 |
2021年 | 78篇 |
2020年 | 38篇 |
2019年 | 45篇 |
2018年 | 51篇 |
2017年 | 67篇 |
2016年 | 64篇 |
2015年 | 67篇 |
2014年 | 111篇 |
2013年 | 112篇 |
2012年 | 101篇 |
2011年 | 124篇 |
2010年 | 82篇 |
2009年 | 95篇 |
2008年 | 101篇 |
2007年 | 88篇 |
2006年 | 59篇 |
2005年 | 48篇 |
2004年 | 48篇 |
2003年 | 48篇 |
2002年 | 27篇 |
2001年 | 39篇 |
2000年 | 40篇 |
1999年 | 40篇 |
1998年 | 35篇 |
1997年 | 22篇 |
1996年 | 25篇 |
1995年 | 22篇 |
1994年 | 15篇 |
1993年 | 16篇 |
1992年 | 8篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有1877条查询结果,搜索用时 15 毫秒
941.
Application and appreciation of chemical sand fixing agent-poly (aspartic acid) and its composites 总被引:2,自引:0,他引:2
The sand fixing agent-poly (aspartic acid) (PASP) and its composites were applied in the field by two forms (spraying around by PASP solution and PASP powder directly). It was found that the sand fixing effect in powder form was not as good as in solution form, but it was more practical in dry region. It needed 9, 6 and 7 days for PASP, xanthan gum-PASP (X2) and ethyl cellulose-PASP (E3) to attain the maximal mechanical strength after they were applied, respectively. The sand fixing effect decreased when the material was subjected to repeated hydration-dehydration cycles and the material had no negative influence on plant growth. The PASP and its composites had water-retaining ability and could reduce the water evaporation. 相似文献
942.
Cao Man Ye Wenhu 《中国人口.资源与环境(英文版)》2007,5(4):26-30
It is difficult to realize the transformation from traditional economy industrial system to circular economy industrial system. Regarding primary raw materials as the indicators, the industrial system has been specified according to the divergence among the indicators and the circular utilization modes. In comparison with the association among industrial systems, the relationship among industrial sub-systems is named as industrial cross-linking in this paper. The industrial system which could completely utiLize and recycle the indicators shouM be increased and strengthened, and the circular economy industrial system with complete industrial association and industrial cross-linking should also be constructed. Taking the development of circular agricultural system basing on the traditional agricultural system as an example, the traditional agricultural products are regarded as the indicators which have been divided into foodstuff and crop straws which are used to produce food and articles for use, Like fertilizer, energy and papers etc. The way to construct the circular agricultural industrial system is to increase the industrial systems that could utilize the products generated from crop straws, feces and other castoffs and transform the wastewater and other trucks into environmental friendly products. It has also been pointed out that the construction of circular economy industrial system is conducive to the foundation of circular industrial economics and the establishment of the construction layout of circular economy and the application schemes. Suggestions to the theoretical and practical work of the next step have also been brought forward in this paper. 相似文献
943.
944.
常州市可持续发展限制因子辨识及发展对策 总被引:1,自引:0,他引:1
本文对我国最早的国家级社会发展综合实验区常州市可持续发展的限制因子进行了辨识,并针对限制因子提出了常州市可持续发展的对策 相似文献
945.
利用微型动物削减剩余污泥量的研究 总被引:3,自引:0,他引:3
在污水的好氧生物处理过程中会产生大量的剩余污泥。污泥的浓缩、脱水、处理和处置需要花费大量的人力和物力 ,而且如果处置不当 ,很容易对环境造成二次污染。因此 ,最大限度减少剩余污泥的排放成为人们关注的问题。根据生态学的理论 ,加强微型动物对细菌的捕食作用 ,可使能量在从低营养级向高营养级传递过程中有一定的损失 ,同时污泥量得以减少。应用两段式生物反应器或者直接向曝气池中投加微型动物均可达到此目的。本文详细地介绍了这两种方法 ,讨论了各自的优点和不足 ,并指出了未来的发展方向 相似文献
946.
Philip Andrews-Speed Armando Zamora Christopher D. Rogers Lei Shen Shelley Cao & Minying Yang 《Natural resources forum》2002,26(1):45-54
The effective management of small-scale mines is one of the major challenges for governments in the mining sector. Small-scale mining may bring tangible, short-term benefits to the communities involved. However, these benefits are frequently outweighed by the costs incurred in terms of illness, injury, pollution, waste of natural resources and market distortions. Governments, international agencies and advisers are generally able to draw up lists of actions which are required to regulate and manage small-scale mines more effectively, but turning plans into sustained action has proved more difficult. Two aspects of policy implementation are crucial to success: the alignment of interests, and the attitude and effectiveness of government. Using a case study of township and village coal mines in China, this article develops an approach to analysing these issues that could assist regional policy makers and advisers in formulating policy, in identifying key obstacles to policy implementation, and in identifying particular parties which need to be infiuenced or educated in order for the policy to succeed. 相似文献
947.
Disharmony between society and environmental carrying capacity: a historical review, with an emphasis on China 总被引:4,自引:0,他引:4
Nature can survive without humans, but humans cannot survive without nature. Despite a clear understanding of this dependency, humans continue to exist in disharmony with nature, and our current environmental and human dilemmas reflect old problems with a long history. Societies have historically experienced many transitions from harmony between nature and society to a crisis of disharmony, followed by a subsequent transition from crisis to harmony. Such ecological crises arise when society no longer practices sustainable consumption of resources within the limits imposed by the environmental carrying capacity. Over the long term, the growth in human desires has always exceeded the growth in the environmental carrying capacity. Science, technology, and social institutions must all be improved to resolve the ecological crises that arise from this imbalance. This paper discusses how increasing understanding of the problem by the public and by decision makers is the key to minimizing the undesirable impacts of the coming bottleneck for sustainable development. Furthermore, we emphasize how this awareness must be translated into fundamental political and economic changes. 相似文献
948.
Evaluation of the thermal/optical reflectance method for discrimination between char- and soot-EC 总被引:4,自引:1,他引:3
Many optical, thermal and chemical methods exist for the measurement of elemental carbon (EC) but are unable or neglect to differentiate between the different forms of EC such as char- or soot-EC. The thermal/optical reflectance (TOR) method applies different temperatures for measuring EC and organic carbon (OC) contents through programmed, progressive heating in a controlled atmosphere, making available eight separate carbon fractions - four OC, one pyrolyzed organic carbon, and three EC. These fractions were defined by temperature protocol, oxidation atmosphere, and laser-light reflectance/transmittance. Stepwise thermal evolutional oxidation of the TOR method makes it possible to distinguish char- from soot-EC. In this study, different EC reference materials, including char and soot, were used for testing it. The thermograms of EC reference materials showed that activation energy is lower for char- than soot-EC. Low-temperature EC1 (550 degrees C in a 98% He/2% O2 atmosphere) is more abundant for char samples. Diesel and n-hexane soot samples exhibit similar EC2 (700 degrees C in a 98% He/2% O2 atmosphere) peaks, while carbon black samples peaks at both EC2 and EC3 (800 degrees C in a 98% He/2% O2 atmosphere). These results supported the use of the TOR method to discriminate between char- and soot-EC. 相似文献
949.
论可持续发展的基本组织单元和层次体系 总被引:9,自引:0,他引:9
在可持续发展的实践中,选择合适的基本组织单元和建立适当的管理层次体系非常重要。本文在论述各种区域划分类型的基础上,提出可持续发展的基本组织单元应以行政功能区划为主,选择市(带县)作为可持续发展的基本组织单元,同时要兼顾经济因素和自然因素;在我国以国家、省、市(带县)作为可持续发展实践的三级体系较为适宜;并论述了区域内部和外部的调控和优化 相似文献
950.
Spectroscopic studies of the progress of humification processes in humic substances extracted from refuse in a landfill 总被引:2,自引:0,他引:2
Humic acids (HA) and fulvic acids (FA) extracted from refuse in a landfill at different landfill ages were characterized by elemental composition, GPC, FTIR, and (13)C CP/MAS NMR. The elemental composition analysis revealed high O/C and low H/C ratios in the FA, indicating a high proportion of O-alkyl and carboxylic acids in the FA. The M(w) and M(n) values and M(w)/M(n) ratios indicated that the HA had a higher molecular weight and were more homogeneous with respect to molecular weight. FTIR spectra showed that the FA had relatively more intense bands assigned to aliphatic structures and were abundant in oxygen-containing function groups. The analytical results of (13)C CP/MAS NMR suggested that there were more oxygenated aliphatic carbons and fewer aromatic carbons in the FA than in the HA. All the results demonstrated that the degree of humification increased with landfill age. 相似文献