全文获取类型
收费全文 | 30963篇 |
免费 | 709篇 |
国内免费 | 5581篇 |
专业分类
安全科学 | 1360篇 |
废物处理 | 1565篇 |
环保管理 | 3432篇 |
综合类 | 10661篇 |
基础理论 | 7036篇 |
环境理论 | 6篇 |
污染及防治 | 9586篇 |
评价与监测 | 1545篇 |
社会与环境 | 1343篇 |
灾害及防治 | 719篇 |
出版年
2023年 | 285篇 |
2022年 | 789篇 |
2021年 | 667篇 |
2020年 | 511篇 |
2019年 | 573篇 |
2018年 | 750篇 |
2017年 | 872篇 |
2016年 | 1029篇 |
2015年 | 1092篇 |
2014年 | 1505篇 |
2013年 | 2860篇 |
2012年 | 1697篇 |
2011年 | 1965篇 |
2010年 | 1485篇 |
2009年 | 1467篇 |
2008年 | 1696篇 |
2007年 | 1606篇 |
2006年 | 1482篇 |
2005年 | 1106篇 |
2004年 | 996篇 |
2003年 | 1065篇 |
2002年 | 962篇 |
2001年 | 1095篇 |
2000年 | 895篇 |
1999年 | 753篇 |
1998年 | 660篇 |
1997年 | 567篇 |
1996年 | 560篇 |
1995年 | 528篇 |
1994年 | 502篇 |
1993年 | 406篇 |
1992年 | 392篇 |
1991年 | 309篇 |
1990年 | 321篇 |
1989年 | 292篇 |
1988年 | 238篇 |
1987年 | 203篇 |
1986年 | 183篇 |
1985年 | 180篇 |
1984年 | 207篇 |
1983年 | 196篇 |
1982年 | 196篇 |
1981年 | 191篇 |
1980年 | 138篇 |
1979年 | 155篇 |
1978年 | 134篇 |
1977年 | 118篇 |
1975年 | 122篇 |
1974年 | 117篇 |
1972年 | 134篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
皖南山区中华猕猴桃的气候适宜性区划 总被引:1,自引:1,他引:1
本文在简要分析皖南山区气候特征的基础上,根据中华猕猴桃的生长习性,提出了发展只结猕猴桃的适宜栽培高度区划,为合理利用山区气候资源发展猕猴桃生产提供科学依据。 相似文献
972.
Barry D. Keim Gregory E. Faiers 《Journal of the American Water Resources Association》1996,32(1):117-124
ABSTRACT: In most studies, quantile estimates of extreme 24-hour rainfall are given in annual probabilities. The probability of experiencing an excessive storm event, however, differs throughout the year. As a result, this paper explored the differences between heavy rainfall distributions by season in Louisiana. It was concluded by using the Kruskal-Wallis and Mann-Whitney tests that the distribution of heavy rainfall events differs significantly between particular seasons at the sites near the Gulf Coast. Furthermore, seasonal frequency curves varied dramatically at the four sites examined. Mixed distributions within these data were not found to be problematic, but the mechanisms that produced the events were found to change seasonally. Extreme heavy rainfall events in winter and spring were primarily generated by frontal weather systems, while summer and fall events had high proportions of events produced by tropical disturbances and airmass (free-convective) conditions. 相似文献
973.
974.
D. E. Barb J. F. Cruise X. Mo 《Journal of the American Water Resources Association》1996,32(3):511-519
ABSTRACT: A model for urban stormwater quality was developed in this study. The basis for the model is the process by which pollutants build up on the watershed surface. For the wet climate of the study site, it was assumed that there exists an interval of time over which the pollutant buildup equals the pollutant washoff (no accumulation of pollutant). The buildup model was represented by a linear function of the antecedent dry time. The buildup function was then linked with a pollutant washoff model represented by a power function of the storm runoff volume. Various time intervals for no net accumulation were tested to calibrate the model. The model was calibrated to observed data for two small urban basins in Baton Rouge, Louisiana, and model results were used to analyze the behavior of phosphorus concentrations in storm runoff from these basins over a long period of time. 相似文献
975.
用数值拟合的方法对1966年以来76个ML≥5.5地震序列的衰减特性进行了较详细的研究,提出从h值的逐日时间扫描和逐日累积时间扫描两个方面去把握地震序列的衰减过程并将其用于强余震(含双震)的预测和震型的快速判定。 相似文献
976.
运用地图学的理论和方法,阐述了灾害地图的性质、内容、功能和作用,介绍了灾害地图的主要类型,探讨了灾害信息图形显示的过程、方法和手段,并提出了开展灾害地图研究的几点建议。 相似文献
977.
Birgitte Rasmussen Carsten D. Gr nberg 《Journal of Loss Prevention in the Process Industries》1997,10(5-6):325-332
A framework for transformation of knowledge and experience from risk analysis to emergency education is presented. An accident model was developed built on the concept “uncontrolled flow of energy (UFOE)”, where essential elements are the state, location and movement of the energy. A UFOE can be considered as the driving force of an accident, e.g. an explosion, a release of heavy gases. A domain model has been developed for representing emergencies occurring in society. A domain is a group of activities with allied goals and elements, and the domain model uses three main categories: status, context and objectives. Ten specific domains have been investigated including process plant, energy production and distribution, natural disasters and different sorts of transport. Totally 25 accident cases were consulted and information was extracted for filling into the schematic representations with two to four cases pr. specific domain. 相似文献
978.
喷射溶气回流浮选工艺处理含油废水 总被引:8,自引:0,他引:8
采用喷射溶气回流浮选工艺处理含油废水,替代原来的全加压溶气浮选工艺,提高了浮选过程的处理效果,增强了系统的抗负荷冲击能力,浮选出水油含量由原来的〈40mg/L降至〈20mg/L,COD由原来的〈150mg/L降至〈110mg/L。 相似文献
979.
Car manufacturers must eliminate automotive shredder residues (ASR). Two ways of incineration are of interest: at 850°C in municipal waste incinerators or at higher temperatures, above 1100°C in cement plants. These processes reduce the mass and the volume of waste to be disposed of in landfills and energy recovery might be possible. Regulations govern the emission of gaseous effluents to control environmental risk. To determine gaseous effluents from a pilot sacle or an industrial incineration plant, an artificial ASR was made by mixing three representative organic polymers present in the real ASR, namely polyvinylchloride, polyurethane and rubber. This mixture was incinerated at 850 and 1100°C in laboratory experiments and the analyses of the principal gaseous effluents such as carbon oxides, nitrogen oxides, volatile organic compounds, hydrochloric and hydrocyanic acids and sulphur compounds are presented and discussed. Lastly, in order to simulate artificial ASR behaviour, the composition of the combustion gases at equilibrium was calculated using a Gibbs energy minimisation code. 相似文献
980.
Activated carbon, developed from fertilizer waste, has been used for the removal of Hg2+, Cr6+, Pb2+, and Cu2+. Mass transfer kinetic approach has been successfully applied for the determination of various parameters necessary for designing a fixed-bed absorber. Parameters selected are the length of the (PAZ) primary adsorption zone (δ), total time involved for the establishment of primary adsorption zone (tx), mass rate of flow to the absorber (Fm), time for primary adsorption zone to move down its length (tδ), amount of adsorbate adsorbed in PAZ from breakpoint to exhaustion (Ms), fractional capacity (f), time of initial formation of PAZ (tf) and per cent saturation of column at break point. Chemical regeneration has been achieved with 1 M HNO3. 相似文献