全文获取类型
收费全文 | 4674篇 |
免费 | 96篇 |
国内免费 | 73篇 |
专业分类
安全科学 | 213篇 |
废物处理 | 233篇 |
环保管理 | 1258篇 |
综合类 | 394篇 |
基础理论 | 1066篇 |
环境理论 | 5篇 |
污染及防治 | 1127篇 |
评价与监测 | 329篇 |
社会与环境 | 170篇 |
灾害及防治 | 48篇 |
出版年
2023年 | 21篇 |
2022年 | 19篇 |
2021年 | 47篇 |
2020年 | 29篇 |
2019年 | 59篇 |
2018年 | 69篇 |
2017年 | 88篇 |
2016年 | 109篇 |
2015年 | 109篇 |
2014年 | 104篇 |
2013年 | 537篇 |
2012年 | 174篇 |
2011年 | 246篇 |
2010年 | 188篇 |
2009年 | 186篇 |
2008年 | 254篇 |
2007年 | 254篇 |
2006年 | 230篇 |
2005年 | 161篇 |
2004年 | 181篇 |
2003年 | 186篇 |
2002年 | 166篇 |
2001年 | 78篇 |
2000年 | 104篇 |
1999年 | 96篇 |
1998年 | 73篇 |
1997年 | 64篇 |
1996年 | 72篇 |
1995年 | 71篇 |
1994年 | 61篇 |
1993年 | 65篇 |
1992年 | 72篇 |
1991年 | 43篇 |
1990年 | 51篇 |
1989年 | 42篇 |
1988年 | 32篇 |
1987年 | 38篇 |
1986年 | 44篇 |
1985年 | 40篇 |
1984年 | 44篇 |
1983年 | 49篇 |
1982年 | 38篇 |
1981年 | 54篇 |
1980年 | 44篇 |
1979年 | 22篇 |
1978年 | 24篇 |
1977年 | 17篇 |
1976年 | 12篇 |
1975年 | 14篇 |
1971年 | 13篇 |
排序方式: 共有4843条查询结果,搜索用时 15 毫秒
121.
122.
George F. Antonious Eric T. Turley Regina R. Hill John C. Snyder 《Journal of environmental science and health. Part. B》2013,48(4):299-304
Organic matter and nutrients in municipal sewage sludge (SS) and chicken manure (CM) could be recycled and used for land farming to enhance fertility and physical properties of soils. Three soil management practices were used at Kentucky State University Research Farm, Franklin County, to study the impact of soil amendments on kale (Brassica oleracea cv. Winterbar) and collard (Brassica oleracea cv. Top Bunch) yields and quality. The three soil management practices were: (i) SS mixed with native soil at 15 t acre?1, (ii) CM mixed with native soil at 15 t acre?1, and (iii) no-mulch (NM) native soil for comparison purposes. At harvest, collard and kale green plants were graded according to USDA standards. Plants grown in CM and SS amended soil produced the greatest number of U.S. No. 1 grade of collard and kale greens compared to NM native soil. Across all treatments, concentrations of ascorbic acid and phenols were generally greater in kale than in collards. Overall, CM and SS enhanced total phenols and ascorbic acid contents of kale and collard compared to NM native soil. We investigated the chemical and physical properties of each of the three soil treatments that might explain variability among treatments and the impact of soil amendments on yield, phenols, and ascorbic acid contents of kale and collard green grown under this practice. 相似文献
123.
One of the more difficult tasks for the scientific writer is to provide a balanced report of a national effort in a selected area of research and development. The difficulty is compounded when the writer elects to be sole author and has himself shared in the research effort; for he will know his own work best and will be tempted to be spokesman for other research groups of whose work he may not be appreciative. 相似文献
124.
Richard Dennis John E. Wilder Dale L. Harmon 《Journal of the Air & Waste Management Association (1995)》2013,63(9):987-992
The analysis of pressure loss characteristics for pulse jet filters suggests that the relationship between dust adhesion to the fabric and the opposing force generated by pulse jet action plays a major role in dust removal. Hence, fabric cleanability is examined in terms of the adhesion-cohesion forces bonding the dust to the fabric vs. the intensity and frequency of the dust dislodgement forces produced by the high energy air pulses. The effect of jet size and location, jet air volume, and the intensity (pressure) and duration of the jet pulses is related to operating pressure loss. The mechanics of energy transfer from the jet pulse to the dustladen fabric are explored in terms of jet pressure, solenoid valve action, the ratio of delivered pulse air volume to bag (tube) volume, and the elastic and flex properties of the felt bags. Effective and actual fabric dust holdings before and after cleaning are discussed with respect to steady-state dust deposition and removal rates, and operating pressure losses. Finally, predictive equations are proposed for estimating pressure loss over a broad range of design and operating parameters. 相似文献
125.
126.
Standard procedures for evaluating environmental impact involve comparison between before and after conditions or scenarios
or between treatment and control site pairs. In many cases, however, endogenous directional change (natural succession) is
expected to occur at a significant rate over the period of concern, particularly for manmade systems such as impoundments.
Static evaluations do not provide an adequate approach to such problems. A new evaluation frame is proposed. Nominal system
behavior over time is characterized by a stochastic envelope around a nominal trajectory. We show that both the state variance
and the sampling variance can change over time. In this context, environmental regulations can be framed as constraints, targets,
or conformance to ideal trajectories. Statistical tests for determining noncompliance are explored relative to process variance,
sample error, and sample size. Criteria are elucidated for choosing properties to monitor, sample size, and sampling interval. 相似文献
127.
This paper is concerned with the failure of published research to provide a framework within which local technology policy could be analysed and evaluated. It firstly describes a simple model of the technological development process. Then, using this model as a base, develops a framework for analysing the main aspects of technological policies. The paper considers the main results of a recent survey of local authority technology development policies and initiatives before providing some overall conclusions relating to the nature, direction and likely effectiveness of such policies. 相似文献
128.
H. Ken Cordell John C. Bergstrom Gregory A. Ashley John Karish 《Journal of the American Water Resources Association》1990,26(1):53-60
ABSTRACT: Outdoor recreation is a major, growing use of water resources in the United States. The economic effects of expenditures by visitors to three recreational river sites on local economies surrounding the sites were estimated using an input-output model (IMPL.AN). Expenditure data were from the Public Area Recreation Visitors Study (PARVS). Results indicate that visitor spending stimulates a considerable amount of economic activity and growth in local economies. Economic effects include increases in total gross output ranging from $2.6 million to $13.4 million, increases in total income ranging from $1.2 million to $5.6 million, and increases in employment ranging from 60 to 292 jobs. 相似文献
129.
ABSTRACT: Local governments often face environmental problems that cross political boundaries. The onus for solution usually falls on the moat severely affected jurisdiction, others do nothing until impacted. Resolution of these problems requires cooperation across political boundaries which means that local governments must be persuaded first that there is a problem, and second that action is required to solve it. This paper presents a method to supply low cost, credible information that can be used to achieve consensus on problem solution. A case study of a lake water quality management problem is described. Formative evaluation techniques was adapted to provide a minimum of evidence which was then used to persuade less impacted local jurisdictions to cooperate in the problem solution. 相似文献
130.
John B. Whitcomb 《Journal of the American Water Resources Association》1990,26(6):921-926
ABSTRACT: A water use model was developed to estimate water savings from installation of low-flow showerheads and toilet displacement devices in residential housing. The model measures household water use in per capita terms with adjustments for age of occupants, household income, if occupants responsible for direct payment of water bill, and type of water fixtures. Detailed data on 308 single family residences involved with a pilot retrofit program in the Seattle, Washington, area were analyzed. We estimated per capita indoor water use to decline by 6.4 and 2.1 percent from complete installation of low-flow showerheads and toilet displacement devices, respectively. 相似文献