全文获取类型
| 收费全文 | 2864篇 |
| 免费 | 805篇 |
| 国内免费 | 126篇 |
专业分类
| 安全科学 | 473篇 |
| 废物处理 | 65篇 |
| 环保管理 | 622篇 |
| 综合类 | 1545篇 |
| 基础理论 | 355篇 |
| 环境理论 | 1篇 |
| 污染及防治 | 328篇 |
| 评价与监测 | 105篇 |
| 社会与环境 | 164篇 |
| 灾害及防治 | 137篇 |
出版年
| 2025年 | 24篇 |
| 2024年 | 107篇 |
| 2023年 | 138篇 |
| 2022年 | 130篇 |
| 2021年 | 154篇 |
| 2020年 | 163篇 |
| 2019年 | 148篇 |
| 2018年 | 136篇 |
| 2017年 | 151篇 |
| 2016年 | 146篇 |
| 2015年 | 135篇 |
| 2014年 | 123篇 |
| 2013年 | 211篇 |
| 2012年 | 210篇 |
| 2011年 | 221篇 |
| 2010年 | 154篇 |
| 2009年 | 129篇 |
| 2008年 | 142篇 |
| 2007年 | 182篇 |
| 2006年 | 166篇 |
| 2005年 | 121篇 |
| 2004年 | 88篇 |
| 2003年 | 111篇 |
| 2002年 | 62篇 |
| 2001年 | 54篇 |
| 2000年 | 48篇 |
| 1999年 | 57篇 |
| 1998年 | 35篇 |
| 1997年 | 28篇 |
| 1996年 | 28篇 |
| 1995年 | 16篇 |
| 1994年 | 11篇 |
| 1993年 | 18篇 |
| 1992年 | 10篇 |
| 1991年 | 14篇 |
| 1990年 | 8篇 |
| 1989年 | 13篇 |
| 1988年 | 6篇 |
| 1986年 | 6篇 |
| 1983年 | 7篇 |
| 1982年 | 7篇 |
| 1981年 | 7篇 |
| 1980年 | 8篇 |
| 1979年 | 8篇 |
| 1977年 | 6篇 |
| 1976年 | 5篇 |
| 1973年 | 5篇 |
| 1972年 | 5篇 |
| 1971年 | 10篇 |
| 1970年 | 4篇 |
排序方式： 共有3795条查询结果，搜索用时 0 毫秒
161.
阐述了循环经济的内涵,分析了煤炭企业传统生产模式存在的问题,指出煤炭企业实施循环经济生产模式的必要性,提出我国煤炭企业建立循环经济生产模式的基本思路。即建立以煤炭企业为中心的小循环生产模式,以大型煤炭生产基地为中心的中循环生产模式和以社会为中心的大循环生产模式,对我国煤炭企业实施循环经济的生产模式具有指导意义。 相似文献
162.
为预防LEAP-1A发动机压力感压子系统(PSS)内部水汽凝结可能导致的感压元件信号出现错误,从而影响发动机的控制和飞行安全的问题,利用仿真手段对PSS进行防结冰改装研究。建立PSS系统的有限元模型,结合真实航班数据,探究机匣内部在不同工况下的结冰条件;分析系统结冰导致的故障模式和严酷度,并研究PSS系统的故障告警模式;在此基础上,设计PSS系统防结冰改装方案,提出防结冰模拟仿真及验证方法,并得到结合试验的结果验证判据。结果表明:基于压力歧管压差控制加热的改装方案能有效避免PSS系统结冰引发的故障,压力差的数值为样机试验提供判据。 相似文献
163.
164.
The Earth may be largely covered with water, but over one billion people are estimated to be without safe drinking water and almost 2.5 billion (40% of the world's population) without adequate sanitation at the outset of the new millennium. The provision of safe water and sanitation for all poses several serious institutional and economic challenges at international, national and local levels. Despite the various political commitments made from the late 1970s onwards, these commitments have remained largely unfulfilled. Even though some efforts to expand coverage have been made over the past two decades, much of those efforts have been undermined by socioeconomic problems and growing population, particularly in the urban areas of developing countries. The water supply and sanitation sector is actually in acute need of new investments for expansion and maintenance of facilities. Nonetheless, some positive trends can be discerned, such as, for example, the increasing recognition of integrated water resources management, environmental sanitation, public-private partnerships and women as a key for improvement and expansion of services. 相似文献
165.
166.
Construction industry intends to promote effective utilization of waste materials obtained from various sources to develop an eco-friendly building material for high performance, life cycle sustainability, and reduction of carbon footprints globally. The current study focusses to produce concrete mix by using industrial wastes such as ground granulated blast furnace slag (BOF) and glass powder (GP). Samples are prepared by utilizing industrial wastes partially for M35 grade concrete. The ground granulated BOF and GP are used with 10%–40% and 0.1%–0.4%, respectively, as the partial replacement of cement. Under different curing periods, the specimens were characterized for their physical and mechanical properties. Test results were analyzed to check the workability, compressive strength, flexural strength, and water absorption of the sample mixes prepared. The highest compressive and flexural strength of the samples are found to be 46.23 MPa and 5.13 MPa, at the optimal replacement of BOF and GP in the proportion of 30% and 0.2%, respectively. 相似文献
167.
Philip Beske Julia Koplin Stefan Seuring 《Corporate Social Responsibility and Environmental Management》2008,15(2):63-75
Sustainable supply chain management requires suppliers to be evaluated against a wider set of criteria. Quality standards (ISO 9000) play a central role for evaluating suppliers' economic performance, e.g. in the automotive industry. Regarding sustainability, the implementation of environmental and social standards could play a similar role. But almost no data is available on their degree of implementation or their importance for supplier evaluation. The aim of this survey (conducted in autumn 2003) was to evaluate whether and to what degree environmental and social standards have been implemented in the German car industry. The survey yielded 111 usable questionnaires, equalling a response rate of 29%. The results of the survey show that environmental standards, particularly ISO 14001, are already widely used, while this is not the case for social standards. The social dimension of sustainability has been lacking in implementation so far. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment. 相似文献
168.
在明确FMEA分析方法意义的基础上,本文对某装备进行故障模式及影响分析,并得出相应结论,以有助于该装备的研制与使用。 相似文献
169.
Clifford W. Randall Bruce S. Huloher Paul H. King 《Journal of the American Water Resources Association》1970,6(4):648-660
The activated sludge process can remove significant amounts of phosphorus from sewage, but the removal efficiency is usually significantly reduced by the release of phosphate back to solution during subsequent treatment steps. This research presents a study of soluble phosphate release from activated sludge with emphasis on defining the factors that affect such release and the actual release mechanisms. Laboratory units were used for experimental purposes. The experiments were designed to study the relationship between soluble phosphate release and various environmental factors such as redox potential (ORP), dissolved oxygen (DO), pH, solids concentration, solids destruction, and sulfate salt addition. The effect of substrate utilization on phosphate uptake and the relationship between uptake characteristics and subsequent phosphate release were also studied. The results show that some phosphate storage occurs during aerobic substrate utilization. Following substrate utilization, activated sludge phosphate release is directly related to the amount of biological stress the organisms are subjected to, and the mechanism of release is primarily cell lysis. The phosphate released per unit sludge under anoxic conditions is relatively constant. Under normal environmental conditions, neither ORP or pH change have a significant affect on phosphate release. 相似文献
170.
J. Philip Burkhalter Timothy C. Martin Richard G. Allen Jeppe Kjaersgaard Erin Wilson Ray Alvarado Jason S. Polly 《Journal of the American Water Resources Association》2013,49(3):498-517
We compared two methods of estimating crop water consumption to assess whether remote sensing techniques provide consumptive use (CU) estimates commensurate with conventional methods. Using available historical satellite and meteorological data, we applied Mapping EvapoTranspiration at high Resolution using Internalized Calibration (METRIC) to 317,455 ha in the South Platte basin, in northeastern Colorado, for the 2001 irrigation season. We then compared these derived CU estimates with values calculated by using the Colorado Water Conservation Board's South Platte Decision Support System StateCU model. Evaluating the data by irrigation ditch service area, we disaggregated the output to allow for comparison by service area size, crop type, irrigation method, water supply source, and water availability. We concluded that METRIC is a suitable alternative to StateCU in the South Platte basin and could help to identify areas with inhibited crop growth or deficit irrigation practices. In addition, METRIC could be used as a complement to StateCU to refine StateCU model parameters, allowing for more accurate estimates of crop water shortages and groundwater recharge associated with irrigation delivery and application. 相似文献