全文获取类型
收费全文 | 1519篇 |
免费 | 57篇 |
国内免费 | 159篇 |
专业分类
安全科学 | 116篇 |
废物处理 | 84篇 |
环保管理 | 884篇 |
综合类 | 369篇 |
基础理论 | 90篇 |
污染及防治 | 58篇 |
评价与监测 | 65篇 |
社会与环境 | 15篇 |
灾害及防治 | 54篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 16篇 |
2020年 | 23篇 |
2019年 | 5篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 19篇 |
2013年 | 25篇 |
2012年 | 16篇 |
2011年 | 30篇 |
2010年 | 29篇 |
2009年 | 24篇 |
2008年 | 57篇 |
2007年 | 13篇 |
2006年 | 21篇 |
2005年 | 17篇 |
2004年 | 38篇 |
2003年 | 70篇 |
2002年 | 159篇 |
2001年 | 142篇 |
2000年 | 174篇 |
1999年 | 134篇 |
1998年 | 103篇 |
1997年 | 80篇 |
1996年 | 214篇 |
1995年 | 60篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 22篇 |
1984年 | 38篇 |
1983年 | 35篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 14篇 |
1967年 | 1篇 |
排序方式: 共有1735条查询结果,搜索用时 503 毫秒
711.
目的研究层涂法制备Pr~(3+):Y_2SiO_5/TiO_2复合薄膜的结构与可见光催化性能。方法分别以钛酸丁酯(TBOT)和正硅酸乙酯(TEOS)为前驱体,通过溶胶-凝胶法制得TiO_2凝胶和Pr掺杂的Y_2SiO_5凝胶,以碳纤维为薄膜载体,并通过浸渍提拉法制备Pr~(3+):Y_2SiO_5/TiO_2层涂薄膜,研究层涂法制备复合薄膜对复合薄膜结构、形貌以及光催化效果的影响。结果复合薄膜具有明显的分层界限,形貌较平整,有较少龟裂;复合薄膜性能受涂覆次序的影响较大。结论依次将Pr~(3+):Y_2SiO_5和TiO_2涂覆在碳纤维上的复合薄膜具有较好的光催化性能,可见光光照2 h,对亚甲基蓝的脱色率达到94%,其可见光催化效率高于TiO_2薄膜的59%。 相似文献
712.
叙述了气垫船减速齿轮箱在海洋大气和海水溅射环境下腐蚀与防护工艺的研究进展。介绍了气垫船减速齿轮箱长期处于高温、高湿、高盐雾以及海水溅射环境下的腐蚀特征和主要腐蚀类型,总结了减速齿轮箱中铝合金、合金钢、不锈钢等不同材质零件腐蚀防护技术的研究进展。最后,提出了海洋环境下气垫船减速齿轮箱的腐蚀防护需从结构设计、材料选型、加工制造、运输贮存、维护保养等方面着手,在充分利用现有表面处理技术的基础上,加强阳极氧化、微弧氧化、电镀、涂料涂层等技术的组合;强化腐蚀监测技术,有效预警防护层失效,同时大力研发海洋环境下长期有效、绿色环保的表面处理和涂层技术。另外,采用系统工程来提高海洋环境下金属材料的环境适应性,进而提高减速齿轮箱等部件的可靠性和安全性。 相似文献
713.
The work aims to characterise PCDDs/Fs in environmental matrices by high resolution gas chromatography coupled to low resolution quadrupole ion-trap mass spectrometry (GC-QITMS/MS). In particular, the study was mainly focused in different environmental samples such as sewage sludge, soils, and sediments and in combustion residues as fly ashes. Previous experiences have already detected and quantified PCDDs/PCDFs in all matrices studied. Moreover, isomer-specific analysis of 2,3,7,8-PCDDs/Fs compounds corroborated good correlation between GC-QITMS/MS and a well-established technique such as high resolution mass spectrometry (HRMS). Finally, QC measures included the participation in intercalibration exercises. Successful results were achieved using GC-QITMS/MS in the analysis of fly ashes, soils and sediment materials. In general, GC-QITMS/MS constitutes an interesting alternative for routine analysis of dioxins in such as matrices. 相似文献
714.
715.
John Van Benschoten William W. Walker Jr. 《Journal of the American Water Resources Association》1984,20(1):109-117
ABSTRACT: A modified version of the U.S. Environmental Protection Agency's QUAL-II water quality simulation model is calibrated and applied to the Lower Winooski River, Vermont. The river flows through the metropolitan Burlington area and is impacted by several industrial and municipal point sources and by operation of hydropower facilities. Several structural modifications are made in the model to improve water quality simulations in rivers impacted by algal growth; these include the addition of organic nitrogen and organic phosphorus compartments and provision for algal uptake of ammonia and/or nitrate nitrogen. The model is interfaced with statistical programs which facilitate tabulation, display, and analysis of observed and predicted concentrations. The model is calibrated and tested against data from two intensive water quality surveys. Applications demonstrate the factors controlling water quality and sensitivities to point source waste management strategies and flow, as influenced by hydropower operations. 相似文献
716.
介绍了原子吸收光谱仪的5种主要的背景校正技术(邻近谱线技术,连续光源法,塞曼法,自吸法及连续光源单色器波长调节法CEWM)及其主要产品,分析评述了各种校正技术的原理,特点及其应用状况。 相似文献
717.
Geoffrey Wandesforde-Smith Iara Verocai Dias Moreira 《Environmental Impact Assessment Review》1985,5(3):223-238
EIA has been instituted in developing countries in the last decade largely in response to outside pressures. Governments have been quick to initiate reforms rather than jeopardize projects that might be key to national development plans. At the subnational level, most projects are not financed by foreign aid. The application of EIA at this level is often the result of pressure exerted on policy elites by the bureaucracy. This paper describes the reorganization of environmental protection agencies in the state of Rio de Janeiro in Brazil. This reorganization provided the setting for a bureaucratic initiative on EIA. The authors also analyze two cases in which EIA was applied unsatisfactorily and comment on the political realites of implementing EIA at the subnational level. 相似文献
718.
John Horberry 《Environmental Impact Assessment Review》1985,5(3):207-222
International EIA activity has two origins. First, there is increasing concern over conflict between developmental and environmental interests within the economic development system. Second, EIA appeals to international agencies and governments as a well-defined, internally integrated procedure and planning tool. EIA activities involve political, institutional, and technical motivations and goals for the international bodies and the governments of countries receiving aid. Three criteria may be used to evaluate international EIA from the perspective of policy makers and administrators in the countries: political support, institutional strengthening, and technical capability. This paper reviews the influence of the United Nations system and of some multilateral and bilateral development assistance agencies in promoting EIA in developing countries. The extent the nature of the influence donors have on EIA in developing countries is shaped as much by the interests and organizational characteristics of the donors as by the needs and priorities of the recipients. 相似文献
719.
陈浩然 《中国安全科学学报》1996,(Z1)
通过对当今安全工作和人才培养的现状进行分析和讨论,提出有关对策和办法。以促使安全工作上一个新台阶,保障企业安全生产,促进国民经济迅猛发展。 相似文献
720.
Sun-Fu Shih 《Journal of the American Water Resources Association》1978,14(4):942-955
ABSTRACT: A first-order autoregressive model had been modified with the trend and cyclical movements to generate the streamflow sequences. Three main portions were involved in this modified model, i.e., six-year cycle with trend changing; six-year cycle without trend changing; and both annual and six-year cycles with trend changing. The synthetic sequences of monthly streamflow sequences were compared with the historical records obtained from the Kissimmee River basin by using the Chi-Square test for goodness-of-fit. The results indicated that the newly proposed model has a better solution than the original model because the trend and cyclical movements involved in generating sequences are much closer to the historical records. 相似文献