全文获取类型
收费全文 | 1096篇 |
免费 | 10篇 |
国内免费 | 36篇 |
专业分类
安全科学 | 58篇 |
废物处理 | 105篇 |
环保管理 | 97篇 |
综合类 | 95篇 |
基础理论 | 167篇 |
环境理论 | 1篇 |
污染及防治 | 404篇 |
评价与监测 | 149篇 |
社会与环境 | 56篇 |
灾害及防治 | 10篇 |
出版年
2023年 | 31篇 |
2022年 | 142篇 |
2021年 | 108篇 |
2020年 | 39篇 |
2019年 | 48篇 |
2018年 | 62篇 |
2017年 | 71篇 |
2016年 | 64篇 |
2015年 | 30篇 |
2014年 | 44篇 |
2013年 | 134篇 |
2012年 | 51篇 |
2011年 | 65篇 |
2010年 | 42篇 |
2009年 | 33篇 |
2008年 | 26篇 |
2007年 | 30篇 |
2006年 | 23篇 |
2005年 | 13篇 |
2004年 | 16篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1964年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有1142条查询结果,搜索用时 140 毫秒
691.
692.
Saeedi Reza Khakzad Saeed Koolivand Ali Dobaradaran Sina Khaloo Shokooh Sadat Jorfi Sahand Abtahi Mehrnoosh 《Environmental science and pollution research international》2017,24(23):19098-19103
Environmental Science and Pollution Research - Polychlorinated biphenyl (PCB) contamination of oils from all transformers of the national electrical grid in Tehran, Qom, and Alborz, three central... 相似文献
693.
Room temperature synthesis of 2H-1,4-benzoxazine derivatives using a recoverable ionic liquid medium
Ali Sharifi M. Saeed Abaee Zahra Mokhtare Mojtaba Mirzaei 《Environmental Chemistry Letters》2014,12(2):365-370
2H-1,4-Benzoxazines are major heterocyclic compounds with interesting biological and synthetic applications. Therefore, it would be very interesting to develop new efficient methods for their synthesis. Here, we synthesized 2H-1,4-benzoxazines in one pot using K2CO3/H2O in the ionic liquid of choice, [omim][BF4]. After reactions, products are extracted from [omim][BF4] by Et2O and the ionic liquid is recovered and successfully reused over several recycles. Results show that high yields of 3-aryl-2H-1,4-benzoxazine derivatives are obtained chemoselectively at room temperature from their corresponding o-aminophenols and phenacyl bromides. To our knowledge, our method represents the most efficient and straightforward route for the synthesis of 3-aryl-2H-1,4-benzoxazine derivatives in short times and under environmentally benign conditions. 相似文献
694.
695.
696.
Ali Salavati-Zadeh Ahmad Javaheri Seyed Vahid Ghavami Vahid Esfahanian Masoud Masih Tehrani Hossein Akbari 《International Journal of Green Energy》2016,13(10):1042-1049
This study investigates the effects of hydrogen enrichment on formation of pollutants and greenhouse gases in gas-fueled spark ignition engines. To this end, a previously validated detailed mechanism is embedded with a comprehensive one-dimensional engine model and the results are verified with experimental observations at different compression ratios and engine loads. The simulations are then performed for different mixtures of hydrogen and natural gas. The results indicate that adding hydrogen increases the cylinder peak pressure at different loads and compression ratios, despite the fact that reduces the amount of carbon monoxide, carbon dioxide, and methane in all the conditions. 相似文献
697.
698.
699.
Zeeda Fatimah Mohamad Norshahzila Idris Azizan Baharuddin 《Waste management (New York, N.Y.)》2011,31(9-10):1905-1906
700.
Ali Vazini Shayan Reza Azar Afza Reza Teimouri 《Journal of Manufacturing Processes》2013,15(4):644-658
This work deals with parametric study of dry wire EDM (WEDM) process of cemented tungsten carbide. Experiments have been conducted using air as dielectric medium to investigate effects of pulse on time, pulse off time, gap set voltage, discharge current and wire tension on cutting velocity (CV) surface roughness (SR) and oversize (OS). Firstly, a series of exploratory experiments were carried out to identify appropriate gas and its pressure. Afterward, preliminary experiments were conducted to investigate effects of process parameters on dry WEDM characteristics and find appropriate ranges for each factor. Then a central composite rotatable method was employed to design experiments based on response surface methodology (RSM). Empirical models were developed to create relationships between process factors and responses by considering to analysis of variances (ANOVA). To increase the predictability of the process, intelligent models have been developed based on back-propagation neural network (BPNN) and accuracy of these models was compared with mathematical models based on root mean square error (RMSE) and prediction error percent (PEP). In order to select optimal solutions in the cases of single-objective and multi-objectives optimization problems, optimization includes two main approaches. First approach was based on mathematical model and desirability function. Also second approach was designed based on neural network and particle swarm optimization. These approaches were applied in both cases of single-objective and multi-objectives optimization problems and their results were compared with together. Results indicated that selection of air at inlet pressure of 1.5 bar is really appropriate for conducting experiments of next stages. Also, the BPNN creates more accurate prediction rather than mathematical model. Moreover, the BPNN-PSO approach was more efficient in optimization of process rather than mathematical model-desirability function in respect with validation tests. 相似文献