全文获取类型
收费全文 | 542篇 |
免费 | 26篇 |
国内免费 | 39篇 |
专业分类
安全科学 | 29篇 |
废物处理 | 24篇 |
环保管理 | 148篇 |
综合类 | 73篇 |
基础理论 | 136篇 |
环境理论 | 2篇 |
污染及防治 | 128篇 |
评价与监测 | 44篇 |
社会与环境 | 18篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 14篇 |
2020年 | 11篇 |
2019年 | 17篇 |
2018年 | 22篇 |
2017年 | 21篇 |
2016年 | 38篇 |
2015年 | 31篇 |
2014年 | 27篇 |
2013年 | 31篇 |
2012年 | 20篇 |
2011年 | 41篇 |
2010年 | 35篇 |
2009年 | 26篇 |
2008年 | 39篇 |
2007年 | 26篇 |
2006年 | 17篇 |
2005年 | 14篇 |
2004年 | 18篇 |
2003年 | 16篇 |
2002年 | 17篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 4篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有607条查询结果,搜索用时 31 毫秒
61.
Russell M. Wise Graham P. von Maltitz Robert J. Scholes Chris Elphinstone Renee Koen 《Mitigation and Adaptation Strategies for Global Change》2009,14(7):579-604
Minimising the cost of repeatedly estimating C (C) stocks is crucial to the financial viability of projects that seek to sell
C credits. Depending on the price of C, this may imply less or more sampling effort than would be applied for science objectives.
In systems with heterogeneous C pools, such as savannas, this translates into a variable-effort sampling strategy that maximises
the marginal additional C that can be claimed per incremental unit of effort expended. Analysis of a savanna in north-eastern
South Africa indicates relatively modest returns per hectare due to the small C quantities and low sequestration rates. Under
these conditions, areas in excess of 1,000 ha and infrequent sampling frequencies of 5–10 years are required to make such
projects financially viable. For such projects the sample variance, number of samples, cost per sample and establishment costs
have negligible impacts on financial viability. It was also found that the soil-C pool contributes up to three times the net
returns of the aboveground C pool and provides a strong argument to monitor soil C for certification and market trading. The
financial viability estimates, however, do not include the management or opportunity costs incurred in changing the land use.
The economies of scale identified in this study combined with the massive area covered by savannas indicate that these additional
costs can be covered. Further research is recommended to quantify these costs and interrogate the feasibility of large scale
(in excess of 10,000 ha) C-sink projects in savanna systems. 相似文献
62.
63.
64.
65.
66.
Chris Bryant 《补救:环境净化治理成本、技术与工艺杂志》1995,6(1):111-113
67.
Incident reporting systems are playing an increasingly important role in the development and maintenance of safety-critical applications. The perceived success of the FAA's Aviation Safety Reporting System (ASRS) and the FDA's MedWatch has led to the establishment of similar national and international schemes. These enable individuals and groups to report their safety concerns in a confidential or anonymous manner. Unfortunately, many of these systems are becoming victims of their own success. The ASRS and MedWatch have both now received over 500,000 submissions. In consequence, the administrators of incident reporting systems increasingly rely upon software tools to support the administration of their systems. In the past, these systems have relied upon ad hoc applications of conventional database technology. However, there are several reasons why this technology is inadequate for many large-scale reporting schemes. In particular, the problems of query formation often result in poor precision and recall. This, in turn, has profound implications for safety-critical applications. Users may fail to identify similar incidents within national or international collections. These ad hoc approaches also neglect the opportunities provided by recent developments in computer assisted interviewing and in the monitoring of retrieval activities to build models of user behavior. These techniques offer a number of potential benefits. For instance, it is possible to automatically detect potential biases in the way that investigators analyze particular incidents. 相似文献
68.
Rational, cost-effective provision of mission-critical environmental management information remains elusive for almost all large enterprises. Even among the best performing companies—best performing from the perspectives of profitability, quality and/or environmental stewardship—environmental management information systems (EMIS) are usually comprised of dozens to hundreds of individual, isolated applications that require costly data capture, training, and maintenance. This article, the first of two, will discuss ways to coordinate information infrastructures with strategic goals and business processes. 相似文献
69.
Our immense national water quality control program has been launched on a wholly empirical basis, much as our ancestors initiated early navigation improvements and flood control. Not only has there been no effort to determine the benefits of water quality control; the theoretical groundwork for optimization has not been developed. Three main national objectives for consideration are national economic efficiency, preserving and improving the national environment for man's use and development (conservation), and regional development. Although popular at present, the regional development objective is not particularly useful from an economic viewpoint. Efficiency objectives other than environmental can be evaluated but are apt to be minor. Other water quality benefits can be broken down appropriately into four main categories: (a) man's recreational environment; (b) man's home environment; (c) man's working environment; (d) intangibles related to scientific, historic, health and cultural values. In management of water quality, various technical relationships must be considered, particularly as to quantity of water needed for waste disposal, and relationship of this use to water supply withdrawals. Advanced waste treatment must be compared with other alternatives, not only of flow augmentation, but also technological process changes, distribution of effluents, and artificial river aeration. 相似文献
70.
Chris FitzGerald 《环境质量管理》1994,4(2):21-33
Successful implementation of environmental management information systems (EMIS) has become essential to the success of total quality environmental management (TQEM) programs. Effective TQEM programs will be early indicators of which companies survive and thrive in today's competitive business environment. Highly competitive industries such as chemicals, electronics, and oil and gas are becoming very effective in cooperating to develop metrics, models, and tools that are based on business processes rather than regulatory edicts. Now electric power companies, newly exposed to market competition, are starting to develop and implement these metrics, standards, and tools. That industry provides a model for joining TQEM and EMIS. 相似文献