全文获取类型
收费全文 | 2742篇 |
免费 | 183篇 |
国内免费 | 64篇 |
专业分类
安全科学 | 167篇 |
废物处理 | 21篇 |
环保管理 | 1165篇 |
综合类 | 820篇 |
基础理论 | 393篇 |
环境理论 | 2篇 |
污染及防治 | 61篇 |
评价与监测 | 82篇 |
社会与环境 | 179篇 |
灾害及防治 | 99篇 |
出版年
2023年 | 19篇 |
2022年 | 41篇 |
2021年 | 54篇 |
2020年 | 67篇 |
2019年 | 55篇 |
2018年 | 61篇 |
2017年 | 91篇 |
2016年 | 111篇 |
2015年 | 100篇 |
2014年 | 95篇 |
2013年 | 142篇 |
2012年 | 97篇 |
2011年 | 159篇 |
2010年 | 104篇 |
2009年 | 134篇 |
2008年 | 128篇 |
2007年 | 139篇 |
2006年 | 130篇 |
2005年 | 114篇 |
2004年 | 94篇 |
2003年 | 105篇 |
2002年 | 72篇 |
2001年 | 75篇 |
2000年 | 82篇 |
1999年 | 91篇 |
1998年 | 54篇 |
1997年 | 53篇 |
1996年 | 46篇 |
1995年 | 45篇 |
1994年 | 31篇 |
1993年 | 23篇 |
1992年 | 30篇 |
1991年 | 22篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 22篇 |
1986年 | 24篇 |
1985年 | 27篇 |
1984年 | 24篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1980年 | 15篇 |
1979年 | 17篇 |
1978年 | 20篇 |
1977年 | 14篇 |
1975年 | 10篇 |
1973年 | 16篇 |
1972年 | 14篇 |
1971年 | 16篇 |
排序方式: 共有2989条查询结果,搜索用时 31 毫秒
251.
Robert V. Sobczak Thomas C. Cambareri 《Journal of the American Water Resources Association》2002,38(3):747-757
ABSTRACT: An inverse‐simulation approach is used to determine optimal strategies for developing public water‐supply systems in a shallow, coastal aquifer on the outermost arm of the Cape Cod peninsula in Massachusetts. Typically a forward simulation (or “trial and error”) approach is used to find best pumping strategies, but the chances of finding success with this tact diminish as the number of potential options grows large. Well locations and pumping rates are optimized with respect to: (1) providing sufficient water to areas of water‐quality impairment, (2) minimizing impacts to nearby surface waters, (3) preventing saltwater contamination due to overpumping, and (4) minimizing financial cost of well development. Potential well sites and water‐supply scenarios are separated into “politically‐based” and “resource‐based” categories to gain insight into the degree that pre‐existing political boundaries hinder best management practices. The approach provides a promising tool in transboundary water‐resources settings because it allows stakeholders to find solutions that best meet everyone's goals, as opposed to pursuing options that will create conflict, or are less than optimal. 相似文献
252.
随着工、农业的发展,洞庭湖区域的环境污染日趋严重。本文较详细地研究了洞庭湖区域的环境整治规划,在各环境要素的规划方面进行了探讨。 相似文献
253.
Since the end of the 1970s, the southern European countries have shown an exceptional reduction in fertility rate. From the
highest levels among the developed nations, these countries dropped beneath the substitution rate level: in Greece there is
an average of about 1.5 children per woman, and Italy (starting three to four years ago), with 1.3 children per woman, is
now the country with the lowest fecundity rate in the world. Land-use planning in southern European small islands therefore
requires substantial revision. In the areas where western civilization began, which are highly populated and have a long history,
cultural and ethnic aspects of tradition are fundamental to environmental management and to the defense of historical heritage.
They also place a strong value on sustaining tourism, the most relevant economic activity, that allows them to survive and
maintain a high welfare level. For some decades they have had populations with a marked presence of young people and high
emigration rates, but now they are fast becoming dominated by the elderly and must prepare for a period of fast reduction
in youth of the workforce, while the peripheral areas of Asia and Africa are entering a sudden demographic growth phase.
The demographic structure has also been deeply altered both by previous migrations and by random variations, as usually happens
in all small communities. Social services for younger and older people have had to be adapted rapidly, reorganizing high-school
management, hospital and health-care structures, in-house assistance, and so on. There is a need to rethink the job market
and favor the immigration of highly specialized workers, which is a necessity for technical evolution. Sustainable development
is constrained nowadays not only by the scarcity of natural resources, but also by the quality and quantity of human resources.
Proper policies for population and land-use planning are highly correlated factors; they have to be considered with respect
of these new, rapid demographic changes. 相似文献
254.
It is a common experience that public administrations tend to shy away from the explicit acknowledgment of quantitative risk
levels. Faced with extreme concentrations of population and of industrial activities, including LPG and liquid chlorine storage,
within a very small land area, Hong Kong has faced up to the issue of major man-made hazards by “thinking the unthinkable”
and adopting explicit risk guidelines. This article describes how these guidelines were developed and the arguments that led
to their adoption. It is emphasized that the risk guidelines are not rigid standards but simply a method of focusing decision
making and ensuring that any decision to contravene the guidelines is taken at an appropriately senior level in the administration.
The way in which the guidelines have been incorporated intimately into the planning and decision-making process is described
and details are given on how this has led to the implementation of a variety of measures that have greatly reduced both societal
and individual risk from certain types of chemical storage and chemical processing installations in Hong Kong.
The opinions in this paper represent the views of the authors and not necessarily those of the Hong Kong Government. 相似文献
255.
256.
John Houlahan W. Andrew. Marcus Adel Shirmohammadi 《Journal of the American Water Resources Association》1992,28(3):553-567
ABSTRACT: This paper presents the results of an investigation of the effects of the Maryland Critical Area Act on generation of non-point source loads of phosphorus, nitrogen, and sediment to the Rhode River estuary. The Simple Method model, the Marcus and Kearney regression model, and the CREAMS model were used to estimate annual loads under: (1) present conditions, (2) maximum land use development allowable under the Act, and (3) two sets of future land use conditions that might occur if the Act were not in place. Results indicate that the Critical Area Act can reduce the present generation of nonpoint nutrient and sediment loadings 20–30 percent from the regulated area. These reductions can occur while preserving agricultural lands and allowing limited residential and urban development. The decrease in nutrient loadings is primarily dependent upon implementation and enforcement of agricultural best management practices (BMPs). The BMPs could reduce present agricultural nutrient loadings by 90 percent to a level comparable to loadings from residential areas. The estimated effectiveness of the Critical Area Act is even greater when compared to potential future nutrient loadings if development in the area remains unregulated. Unrestricted residential and urban development could increase nutrient loadings by 200 percent to 1000 percent as compared to controlled development under Critical Area Act guidelines. The Critical Area Act primarily prevents these future increases by severely limiting woodland cutting, with lesser results obtained by requiring urban BMPs. 相似文献
257.
本文在论述土地使用权出让和土地利用总体规划内涵的基础上,研究了两者作用和反作用的关系,提出了两者最终目标一致性的观点,并探讨了实践上相关的问题。 相似文献
258.
Environmental planning,ecosystem science,and ecosystem approaches for integrating environment and development 总被引:3,自引:0,他引:3
D. Scott Slocombe 《Environmental management》1993,17(3):289-303
Currently popular concepts such as sustainable development and sustainability seek the integration of environment and development
planning. However, there is little evidence that this integration is occurring in either mainstream development planning or
environmental planning. This is a function of the history, philosophies, and evolved roles of both. A brief review of the
experience and results of mainstream planning, environmental planning, and ecosystem science suggests there is much in past
scientific and professional practice that is relevant to the goal of integrated planning for environment and development,
but still such commonly recommended reforms as systems and multidisciplinary approaches, institutional integration, and participatory,
goal-oriented processes are rarely achieved. “Ecosystem approaches,” as developed and applied in ecology, human ecology, environmental
planning, anthropology, psychology, and other disciplines, may provide a more transdisciplinary route to successful integration
of environment and development. Experience with ecosystem approaches is reviewed, their advantages and disadvantages are discussed,
and they are compared to traditional urban and regional planning, environmental planning, and ecosystem science approaches.
Ultimately a synthesis of desirable characteristics for a framework to integrate environment and development planning is presented
as a guide for future work and a criterion for evaluating existing programs. 相似文献
259.
论事故与系统危险性的关系 总被引:3,自引:1,他引:3
陈森尧 《中国安全科学学报》1993,3(1):46-52
对安全评价中的一些基本概念和参数作了明确的论述,如危险、事故、系统危险性、事故链、固有危险和危险特性、发生事故的难易度与事故概率以及系统可靠度。对澄清当前尚有争论的概念有所帮助,有利于安全评价的顺利进行,也有利于安全科学学科建设。最后对系统危险性的发展趋势作了几点预测。 相似文献
260.
W. A. White L. F. Tischler T. A. Austin 《Journal of the American Water Resources Association》1972,8(3):483-494
ABSTRACT A methodology for predicting the spatial and temporal levels of conservative water quality constituents within a multibasin water resource system is presented. Dissolved solids, sulfates, and chlorides are the constituents used during this investigation; however, any other conservative ion or mineral can be incorporated into the simulation model. The methodology is tested on the proposed Texas Water System. The water quality model, QNET-I, utilizes monthly canal and river flows and reservoir storage levels calculated by the Texas Water Development Board's systems simulation model. Discharge-concentration relationships are developed for each source of water in the system, including significant waste-water discharges. Reservoirs in the system are assumed to be completely mixed with respect to conservative constituents. A mass balance analysis is performed for each node and each month during the simulation period. The output from the water quality simulation is a table of the concentrations of the conservative water quality constituents at each demand point in the system and in each reservoir and canal for every month the system is in operation. The desired quality of the water at the demand locations is used to determine the economic utility of transporting and mixing water from various sources. 相似文献