全文获取类型
收费全文 | 604篇 |
免费 | 43篇 |
国内免费 | 64篇 |
专业分类
安全科学 | 155篇 |
废物处理 | 5篇 |
环保管理 | 209篇 |
综合类 | 157篇 |
基础理论 | 76篇 |
污染及防治 | 34篇 |
评价与监测 | 41篇 |
社会与环境 | 20篇 |
灾害及防治 | 14篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 20篇 |
2018年 | 12篇 |
2017年 | 26篇 |
2016年 | 22篇 |
2015年 | 21篇 |
2014年 | 19篇 |
2013年 | 34篇 |
2012年 | 31篇 |
2011年 | 32篇 |
2010年 | 24篇 |
2009年 | 36篇 |
2008年 | 22篇 |
2007年 | 54篇 |
2006年 | 46篇 |
2005年 | 25篇 |
2004年 | 24篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 14篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 24篇 |
1995年 | 15篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有711条查询结果,搜索用时 0 毫秒
581.
582.
583.
为对建筑业政府安全监管效率进行科学合理的评价,优化资源配置,提高资源利用率,提升监管水平,在建立效率评价指标体系的基础上,将数据包络分析法(DEA)和优劣解距离法(TOPSIS)组合,构建建筑业政府安全监管效率评价模型,对2012—2019年西安市建筑业政府安全监管效率进行实证分析。结果表明:该模型能较好地应用于建筑业政府安全监管效率评价,通过获取政府投入指标的松弛变量值,分析建筑业政府安全监管效率,为政府优化资源配置提供借鉴。 相似文献
584.
In present investigation, an attempt has been made for the synthesis of cupric oxide nanoparticles (CuONPs) through a green route by utilizing lemon juice extract as a bioreductant. The synthesized CuONPs were characterized through UV–visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The CuONPs were utilized for Cr(VI) removal from water through adsorption method in batch mode at different initial Cr(VI) concentration, pH, temperature and CuONPs dosage. The maximum uptake capacity of CuONPs was found to be 16.63 mg of Cr(VI)/g at pH 4.0. Implementation of response surface methodology (RSM) followed by artificial neural network hybridized with genetic algorithm (ANN-GA) approach has resulted maximum Cr(VI) adsorption of 98.8% under the optimized conditions of initial metal concentration 22.5 mg/L, pH 3.81, CuONPs dose 1.28 g/L and temperature 37.1 °C. Under optimum conditions, adsorption isotherm study was conducted, which showed that the fitness of experimental data was well achieved with Langmuir isotherm model illustrating monolayer pattern of adsorption. Thermodynamic study revealed that the process was spontaneous and endothermic in nature, while adsorption kinetics was best explained by pseudo-second order kinetic model. 相似文献
585.
简要统计了2015年7-8月国内发生的各种环境事件150起,包括沙尘天气3起,污染事件18起,地震55起,山体滑坡和泥石流22起,旱灾2起以及其他自然灾害50起. 相似文献
586.
587.
聚结除油反应机理及其动力学分析 总被引:1,自引:0,他引:1
通过对几种聚结填料除油性能的对比试验,探讨分析了聚结除油反应机理及其动力学.结果表明,填料的空间构成形式对聚结除油效率有重要影响,当润湿聚结机理和碰撞聚结机理同时存在时,聚结效率可得到大幅度提高.当油珠颗粒尺寸超过10μm时,布朗运动聚结速率急剧减慢,而湍流的聚结速率急剧加快.聚结除油反应器内水力条件的紊动程度达到G≥500~700 s-1时,油珠颗粒的聚结速率和效率将得到大幅度提高. 相似文献
588.
We develop regional-scale eutrophication models for lakes, ponds, and reservoirs to investigate the link between nutrients and chlorophyll-a. The Bayesian TREED (BTREED) model approach allows association of multiple environmental stressors with biological responses, and quantification of uncertainty sources in the empirical water quality model. Nutrient data for lakes, ponds, and reservoirs across the United States were obtained from the Environmental Protection Agency (EPA) National Nutrient Criteria Database. The nutrient data consist of measurements for both stressor variables (such as total nitrogen and total phosphorus), and response variables (such as chlorophyll-a), used in the BTREED model. Markov chain Monte Carlo (McMC) posterior exploration guides a stochastic search through a rich suite of candidate trees toward models that better fit the data. The Bayes factor provides a goodness of fit criterion for comparison of resultant models. We randomly split the data into training and test sets; the training data were used in model estimation, and the test data were used to evaluate out-of-sample predictive performance of the model. An average relative efficiency of 1.02 between the training and test data for the four highest log-likelihood models suggests good out-of-sample predictive performance. Reduced model uncertainty relative to over-parameterized alternative models makes the BTREED models useful for nutrient criteria development, providing the link between nutrient stressors and meaningful eutrophication response. 相似文献
589.
Concentrations (c) of lindane and technical DDT have been determined in about 60 soil samples, randomly taken from a 10 × 10 m2 plot of bare soil one day after spraying. These experimental c, log c data, and literature data for dieldrin are used to examine the various residue distributions in cultivated and uncultivated soil plots. The normality of these distributions is examined with some statistical tests. All c distribution curves are more or less skew to higher c levels. From the pooled cumulative distribution curve and frequency histogram it is concluded that the found c distributions can be characterized best as bimodal. Finally, some practical recommendations are given for cost‐effective soil sampling. 相似文献
590.
简要统计了2015年3-4月国内发生的各种环境事件112起,包括沙尘天气17起,污染事件21起,地震42起,山体滑坡和泥石流7起,旱灾4起以及其他自然灾害21起. 相似文献