全文获取类型
收费全文 | 27673篇 |
免费 | 257篇 |
国内免费 | 201篇 |
专业分类
安全科学 | 707篇 |
废物处理 | 927篇 |
环保管理 | 3615篇 |
综合类 | 7592篇 |
基础理论 | 6184篇 |
环境理论 | 8篇 |
污染及防治 | 6739篇 |
评价与监测 | 1338篇 |
社会与环境 | 897篇 |
灾害及防治 | 124篇 |
出版年
2018年 | 305篇 |
2017年 | 296篇 |
2016年 | 437篇 |
2015年 | 338篇 |
2014年 | 479篇 |
2013年 | 1975篇 |
2012年 | 624篇 |
2011年 | 896篇 |
2010年 | 740篇 |
2009年 | 868篇 |
2008年 | 937篇 |
2007年 | 995篇 |
2006年 | 887篇 |
2005年 | 740篇 |
2004年 | 776篇 |
2003年 | 777篇 |
2002年 | 698篇 |
2001年 | 973篇 |
2000年 | 667篇 |
1999年 | 455篇 |
1998年 | 332篇 |
1997年 | 306篇 |
1996年 | 351篇 |
1995年 | 376篇 |
1994年 | 402篇 |
1993年 | 354篇 |
1992年 | 375篇 |
1991年 | 366篇 |
1990年 | 404篇 |
1989年 | 395篇 |
1988年 | 318篇 |
1987年 | 317篇 |
1986年 | 294篇 |
1985年 | 307篇 |
1984年 | 314篇 |
1983年 | 309篇 |
1982年 | 320篇 |
1981年 | 336篇 |
1980年 | 286篇 |
1979年 | 294篇 |
1978年 | 255篇 |
1977年 | 230篇 |
1976年 | 247篇 |
1974年 | 260篇 |
1973年 | 238篇 |
1972年 | 229篇 |
1971年 | 217篇 |
1968年 | 229篇 |
1967年 | 259篇 |
1966年 | 222篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
41.
42.
43.
44.
E.W. Lees 《Natural resources forum》1993,17(4):288-293
Energy efficiency is often stated to be the most cost-effective measure for satisfying our energy demand with minimal environmental damage. However, the potential energy savings attainable in 'the real world' are frequently overestimated, as is shown in an industrial case study of the glass industry. Nevertheless, there are significant energy savings to be realized, and the role of new technologies in this is important. However, the key to the effective use of new technology for improved energy efficiency is good management and. for best effect, it must be integrated into the normal resource management activities of a company. 相似文献
45.
An experimental investigation of explanations for inconsistencies in responses to second offers in double referenda 总被引:1,自引:0,他引:1
Anthony C. Burton Katherine S. Carson Susan M. Chilton W. George Hutchinson 《Journal of Environmental Economics and Management》2003,46(3):472
This paper demonstrates the potential for induced preference experiments to test previously unverified explanations of observed behavior in contingent valuation surveys. The NOAA Panel on Contingent Valuation called for experimental evidence on potential biases in the double referendum format. We test Carson, Groves, and Machina's (Incentives and informational properties of preference questions, Plenary address to the European Association of Resource and Environmental Economists, Oslo, Norway, June 1999) simple cost uncertainty and weighted averaging explanations of inconsistent responses to follow-up offers in such double referenda against a baseline of certainty and truthful preference revelation. The results find evidence to support the Weighted Average hypothesis. Results regarding the cost uncertainty hypothesis are more ambiguous and merit further investigation. 相似文献
46.
ABSTRACT: Two dynamic programming models — one deterministic and one stochastic — that may be used to generate reservoir operating rules are compared. The deterministic model (DPR) consists of an algorithm that cycles through three components: a dynamic program, a regression analysis, and a simulation. In this model, the correlation between the general operating rules, defined by the regression analysis and evaluated in the simulation, and the optimal deterministic operation defined by the dynamic program is increased through an iterative process. The stochastic dynamic program (SDP) describes streamflows with a discrete lag-one Markov process. To test the usefulness of both models in generating reservoir operating rules, real-time reservoir operation simulation models are constructed for three hydrologically different sites. The rules generated by DPR and SDP are then applied in the operation simulation model and their performance is evaluated. For the test cases, the DPR generated rules are more effective in the operation of medium to very large reservoirs and the SDP generated rules are more effective for the operation of small reservoirs. 相似文献
47.
A significant positive correlation between the lipid content of eight fish species and their bioconcentration factor (BCF) of 1,2,4-trichlorobenzene is demonstrated. The log BCF value on a lipid basis is in good agreement with the log n-octanol/water partition coefficient. 相似文献
48.
W. F. Wood 《Marine Biology》1987,96(1):143-150
During spring and summer, 1982–1986, experiments were carried out near Marmion Reef, Western Australia. In summer, nearly 30% of the surface solar ultraviolet radiation (280 to 400 nm) penetrates offshore waters to 5 m depth. Experimental removal of the mature Ecklonia radiata kelp canopy in summer results in tissue damage, photopigment destruction, reduced growth, and low survivorship of subcanopy kelp sporophytes. These effects do not occur with canopy removal in winter. Laboratory experiments revealed that the UV component of radiation, rather than intense photosynthetically active radiation, was responsible for the inhibition of growth and photodamage. UV radiation probably affects survival of the settlement stages of E. radiata sporophytes, thus excluding them from otherwise suitable substrata in shallow waters. UV radiation is implicated in the reduction of canopy productivity in summer. 相似文献
49.
50.
We report three siblings from consecutive pregnancies affected with restrictive dermopathy (RD). During the second pregnancy, fetal behavioural development and growth were studied extensively using ultrasound at 1–4 week intervals. Dramatic and sudden changes occurred in fetal body movements and growth but not until the end of the second trimester of pregnancy. Prominent at that time were prolonged periods of fetal quiescence and very low heart rate variability, together with abnormally executed body movements of short duration. Retarded femoral development and jerky abrupt fetal body movements (abnormal movement quality) were already present in the early second trimester of pregnancy. Facial anomalies emerged despite the presence of fetal mouth movements. The clinical features of RD were only partly explained by present knowledge of skin development and the fetal akinesia deformation sequence hypothesis. Quantitative assessment of fetal movements proved to be a poor early marker for antenatal diagnosis of this disorder. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献