全文获取类型
收费全文 | 13002篇 |
免费 | 955篇 |
国内免费 | 3827篇 |
专业分类
安全科学 | 931篇 |
废物处理 | 1239篇 |
环保管理 | 1831篇 |
综合类 | 9139篇 |
基础理论 | 1420篇 |
环境理论 | 3篇 |
污染及防治 | 2410篇 |
评价与监测 | 401篇 |
社会与环境 | 364篇 |
灾害及防治 | 46篇 |
出版年
2024年 | 15篇 |
2023年 | 93篇 |
2022年 | 198篇 |
2021年 | 273篇 |
2020年 | 334篇 |
2019年 | 291篇 |
2018年 | 284篇 |
2017年 | 330篇 |
2016年 | 434篇 |
2015年 | 537篇 |
2014年 | 793篇 |
2013年 | 926篇 |
2012年 | 1115篇 |
2011年 | 1135篇 |
2010年 | 917篇 |
2009年 | 924篇 |
2008年 | 705篇 |
2007年 | 1162篇 |
2006年 | 1245篇 |
2005年 | 928篇 |
2004年 | 735篇 |
2003年 | 777篇 |
2002年 | 656篇 |
2001年 | 562篇 |
2000年 | 487篇 |
1999年 | 433篇 |
1998年 | 314篇 |
1997年 | 253篇 |
1996年 | 211篇 |
1995年 | 181篇 |
1994年 | 152篇 |
1993年 | 121篇 |
1992年 | 71篇 |
1991年 | 47篇 |
1990年 | 40篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1984年 | 7篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1971年 | 6篇 |
1970年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
A sequencing batch reactor was modeled using multi-layer perceptron and radial basis function artificial neural networks (MLPANN and RBFANN). Then, the effects of influent concentration (IC), filling time (FT), reaction time (RT), aeration intensity (AI), SRT and MLVSS concentration were examined on the effluent concentrations of TSS, TP, COD and NH4+-N. The results showed that the optimal removal efficiencies would be obtained at FT of 1 h, RT of 6 h, aeration intensity of 0.88 m3/min and SRT of 30 days. In addition, COD and TSS removal efficiencies decreased and TP and NH4+-N removal efficiencies did not change significantly with increases of influent concentration. The TSS, TP, COD and NH4+-N removal efficiencies were 86%, 79%, 94% and 93%, respectively. The training procedures of all contaminants were highly collaborated for both RBFANN and MLPANN models. The results of training and testing data sets showed an almost perfect match between the experimental and the simulated effluent of TSS, TP, COD and NH4+-N. The results indicated that with low experimental values of input data to train ANNs the MLPANN models compared to RBFANN models are more precise due to their higher coefficient of determination (R2) and lower root mean squared errors (RMSE) values. 相似文献
2.
燃煤电厂海水烟气脱硫工艺原理初探 总被引:12,自引:1,他引:11
海水烟气脱硫工艺是利用天然的纯海水(燃煤电厂可直接利用电厂的冷却循环水)作为烟气中SO2的吸收剂,无需其它任何添加剂,也不产生任何废弃物,具有技术成熟、工艺简单、系统运行可靠、脱硫效率高(理论脱硫效率可达98%)和投资运行费用低等特点,目前在一些国家和地区已得到日益广泛的应用。本文是在部分模拟试验的基础上,对海水烟气脱硫工艺进行了简单的阐述。 相似文献
3.
面对人口老龄化对经济发展的影响.应以养老和健康保障为先导.逐步加大对社会保障基金的投入.充实基本养老保险和医疗保险基金.建立和完善与生产力发展水平相适应的社会保障制度.继续推进社会保障社会化和产业结构调整的力度.建议政府应大力发展老龄产业。政府必须从实际出发.坚持科学发展观.逐步建立和完善老年社会养老制度和福利制度.根据老年消费市场状况.规范、引导投资.调整、优化产业结构用产业化、市场化、社会化的新运行机制.推进安老、养老产业的发展.根据老年人的不同需求,有计划的发展老龄产业、开发老年用品.增设老年服务项目.满足老年人在物质和文化方面的发展需要.以促使人口老龄化与经济的协调发展。 相似文献
4.
重点开发长江是90年代中国经济重大战略布署。将长江产业带建设成具有强大经济实力的国家一级经济轴线,宜采用分层次推进与中心辐射相结合的发展战略,以浦东开发和三峡建设为契机,加强基础产业,发展新兴产业和第三产业,优化产业结构,以能源和交通建设先行,改善基础设施。同时,要协调产业带建设与浦东开发、三峡工程建设的关系。 相似文献
5.
阐述了开展工业区群环境影响评价的意义,比较了单个工业园区和工业区群环评的异同,以广州番禺区工业区群环评项目为例,简述了该环评的主要内容和特点,并提出了建议。 相似文献
6.
G. D. Kataev 《Russian Journal of Ecology》2005,36(6):421-426
The effect of industrial air pollution on natural small mammal populations has been studied in the northern taiga subzone of the boreal forest zone. The results of long-term monitoring have been used to demonstrate the possibility of predicting changes in the main population and community characteristics of the animal species studied as dependent on the degree of anthropogenic impact. 相似文献
7.
Joachim Ruther 《Chemoecology》2004,14(3-4):187-192
Summary. Field tests were performed to evaluate the
response of the garden chafer, Phyllopertha horticola
(Coleoptera: Scarabaeidae) to known scarab attractants and to
investigate the influence of trap colour and height on the
number of captured beetles. Both sexes were attracted by a
lure mixture composed of geraniol, eugenol, and 2-phenylethyl
propionate (PEP) (ratio 3:7:3). When testing floral volatiles
individually, only geraniol, eugenol and methyl anthranilate
but not PEP was attractive. Response of garden chafer to (Z)-
3-hexen-1-ol was strongly male-biassed. Both the response
to floral volatiles and (Z)-3-hexen-1-ol was increased by
using funnel traps with yellow instead of grey vanes. Traps
positioned at 50 and 125 cm above ground captured significantly
more garden chafers than those at 200 cm. The
strongly male-biassed response to (Z)-3-hexen-1-ol suggests
that in P. horticola (subfamily Rutelinae) orientation towards plant volatiles emitted upon mechanical damage of plants is
part of the male mate finding strategy as recently demonstrated
for cockchafers of the genus Melolontha (subfamily Melolonthinae). Possible application of plant volatiles for
control of P. horticola is discussed. 相似文献
8.
Russian Journal of Ecology - 相似文献
9.
The effect of mountain relief and industrial air pollution on biometric parameters of pine stands was studied. The empirical–statistical models of the dependence of biometric characteristics on the parameters of forest sites were developed using raster modeling and multivariate analysis. The possibility of predicting changes in the biometric parameters at any site on the basis of these models is shown. 相似文献
10.
Methodological Basis of Ecological Safety Standards for the Technogenic Impact of Mineral Resource Exploitation 总被引:1,自引:0,他引:1
A new methodological approach to the development of biological and technological safety standards for the impact of underground mining on the natural biota is proposed. 相似文献