全文获取类型
收费全文 | 40049篇 |
免费 | 428篇 |
国内免费 | 323篇 |
专业分类
安全科学 | 1095篇 |
废物处理 | 1514篇 |
环保管理 | 5299篇 |
综合类 | 6421篇 |
基础理论 | 11379篇 |
环境理论 | 24篇 |
污染及防治 | 10371篇 |
评价与监测 | 2484篇 |
社会与环境 | 1949篇 |
灾害及防治 | 264篇 |
出版年
2022年 | 280篇 |
2021年 | 261篇 |
2019年 | 293篇 |
2018年 | 524篇 |
2017年 | 560篇 |
2016年 | 791篇 |
2015年 | 668篇 |
2014年 | 980篇 |
2013年 | 3037篇 |
2012年 | 1183篇 |
2011年 | 1735篇 |
2010年 | 1441篇 |
2009年 | 1433篇 |
2008年 | 1688篇 |
2007年 | 1810篇 |
2006年 | 1591篇 |
2005年 | 1339篇 |
2004年 | 1327篇 |
2003年 | 1276篇 |
2002年 | 1238篇 |
2001年 | 1630篇 |
2000年 | 1163篇 |
1999年 | 718篇 |
1998年 | 536篇 |
1997年 | 565篇 |
1996年 | 574篇 |
1995年 | 630篇 |
1994年 | 575篇 |
1993年 | 511篇 |
1992年 | 539篇 |
1991年 | 490篇 |
1990年 | 500篇 |
1989年 | 528篇 |
1988年 | 446篇 |
1987年 | 404篇 |
1986年 | 377篇 |
1985年 | 401篇 |
1984年 | 399篇 |
1983年 | 420篇 |
1982年 | 409篇 |
1981年 | 347篇 |
1980年 | 320篇 |
1979年 | 351篇 |
1978年 | 300篇 |
1977年 | 265篇 |
1976年 | 244篇 |
1975年 | 244篇 |
1974年 | 232篇 |
1973年 | 245篇 |
1972年 | 264篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
391.
V.S. Yaliwal P.G. Tewari S.Y. Adaganti 《International Journal of Sustainable Engineering》2014,7(3):269-282
Renewable and alternative fuels have numerous advantages compared with fossil fuels as they are renewable and biodegradable and provide food and energy security and foreign exchange savings besides addressing environmental concerns and socio-economic issues (Yaliwal et al. 2013. International Journal of Sustainable Engineering, doi:10.1080/19397038.2013.801530. Zhu et al. 2011a, Applied Thermal Engineering 31 (14–15): 2271–2278; Zhu et al. 2011b, Fuel 90: 1743-1750; Banapurmath, Tewari, and Hosmath 2008, Renewable Energy 33: 2007-2018; Banapurmath 2009, “Performance, Combustion and Emission Characteristics of a Single Cylinder Direct Injection CI Engine Operated on Dual Fuel Mode Using Honge Oil and Producer Gas.” PhD thesis, 1–195; Banapurmath et al. 2011, Waste and Biomass Valorization 2: 1–11). In this context, the main objective of the present work is to study methods of biofuel production such as Honge oil methyl ester (HOME) using a conventional transesterification process and bioethanol from the Calliandra calothyrsus shrub using a new pretreatment method known as hydrothermal explosion. Further, experimental investigations were carried out on a single-cylinder, four-stroke, direct-injection stationary diesel engine operating in a dual-fuel mode using HOME, bioethanol and producer gas combinations to determine its performance, combustion and emission characteristics. The performance of the dual-fuel engine was analyzed at optimized engine conditions. HOME-Bioethanol (BE) blends such as HOME+ 5% bioethanol (BE5), HOME+ 10% bioethanol (BE10) and HOME+ 15% bioethanol (BE15) were prepared by adding bioethanol to HOME (on volume basis) in different proportions ranging from 5 to 15% with an increment of 5%. In this present work, the effect of different BE blends on the performance of producer gas fuelled dual fuel engine was studied. Experimental investigation on dual fuel engine using BE5-Producer gas operation resulted in up to 4–9% increased brake thermal efficiency with decreased hydrocarbon (HC), carbon monoxide (CO) and marginally increased nitric oxide (NOx) emission levels compared to HOME-Producer gas, BE10-producer gas and BE15-producer gas mode of operation. However, it was observed that, the overall performance of BE-producer gas operation was found to be lower compared to diesel-producer gas operation. 相似文献
392.
S. J. Metcalf E. I. van Putten S. D. Frusher M. Tull N. Marshall 《Sustainability Science》2014,9(3):247-261
Identifying effective adaptation strategies for coastal communities dependent on marine resources and impacted by climate change can be difficult due to the dynamic nature of marine ecosystems. The task is more difficult if current and predicted shifts in social and economic trends are considered. Information about social and economic change is often limited to qualitative data. A combination of qualitative and quantitative models provide the flexibility to allow the assessment of current and future ecological and socio-economic risks and can provide information on alternative adaptations. Here, we demonstrate how stakeholder input, qualitative models and Bayesian belief networks (BBNs) can provide semi-quantitative predictions, including uncertainty levels, for the assessment of climate and non-climate-driven change in a case study community. Issues are identified, including the need to increase the capacity of the community to cope with change. Adaptation strategies are identified that alter positive feedback cycles contributing to a continued decline in population, local employment and retail spending. For instance, the diversification of employment opportunities and the attraction of new residents of different ages would be beneficial in preventing further population decline. Some impacts of climate change can be combated through recreational bag or size limits and monitoring of popular range-shifted species that are currently unmanaged, to reduce the potential for excessive removal. Our results also demonstrate that combining BBNs and qualitative models can assist with the effective communication of information between stakeholders and researchers. Furthermore, the combination of techniques provides a dynamic, learning-based, semi-quantitative approach for the assessment of climate and socio-economic impacts and the identification of potential adaptation strategies. 相似文献
393.
Christopher E. Rushton James E. Tate Simon P. Shepherd David C. Carslaw 《Journal of the Air & Waste Management Association (1995)》2018,68(2):111-122
Emissions of nitrogen oxides (NOx) by vehicles in real driving environments are only partially understood. This has been brought to the attention of the world with recent revelations of the cheating of the type of approval tests exposed in the dieselgate scandal. Remote-sensing devices offer investigators an opportunity to directly measure in situ real driving emissions of tens of thousands of vehicles. Remote-sensing NO2 measurements are not as widely available as would be desirable. The aim of this study is to improve the ability of investigators to estimate the NO2 emissions and to improve the confidence of the total NOx results calculated from standard remote-sensing device (RSD) measurements. The accuracy of the RSD speed and acceleration module was also validated using state-of-the-art onboard global positioning system (GPS) tracking. Two RSDs used in roadside vehicle emissions surveys were tested side by side under off-carriageway conditions away from transient pollution sources to ascertain the consistency of their measurements. The speed correlation was consistent across the range of measurements at 95% confidence and the acceleration correlation was consistent at 95% confidence intervals for all but the most extreme acceleration cases. VSP was consistent at 95% confidence across all measurements except for those at VSP ≥ 15 kW t?1, which show a small underestimate. The controlled distribution gas nitric oxide measurements follow a normal distribution with 2σ equal to 18.9% of the mean, compared to 15% observed during factory calibration indicative of additional error introduced into the system. Systematic errors of +84 ppm were observed but within the tolerance of the control gas. Interinstrument correlation was performed, with the relationship between the FEAT and the RSD4600 being linear with a gradient of 0.93 and an R2 of 0.85, indicating good correlation. A new method to calculate NOx emissions using fractional NO2 combined with NO measurements made by the RSD4600 was constructed, validated, and shown to be more accurate than previous methods.Implications: Synchronized remote-sensing measurements of NO were taken using two different remote-sensing devices in an off-road study. It was found that the measurements taken by both instruments were well correlated. Fractional NO2 measurements from a prior study, measurable on only one device, were used to create new NOx emission factors for the device that could not be measured by the second device. These estimates were validated against direct measurement of total NOx emission factors and shown to be an improvement on previous methodologies. Validation of vehicle-specific power was performed with good correlation observed. 相似文献
394.
Sarmila Tandukar Samendra P. Sherchan Eiji Haramoto 《Food and environmental virology》2020,12(3):260-263
This study assessed wastewater quality through the quantification of four human enteric viruses and the applicability of pepper mild mottle virus (PMMoV) a 相似文献
395.
Victor E. Balderas-Hernández José T. Ornelas-Salas Ana P. Barba de la Rosa 《Journal of environmental science and health. Part. B》2020,55(2):148-154
AbstractThe presence of diethyl-phthalate (DEP), dibutyl-phthalate (DBP), butylbenzyl-phthalate (BBP), diethylhexyl-phthalate (DEHP) and diisononyl-phthalate (DINP) was determined in 295 tequila samples. They were grouped by age of maturation (white, aged, extra aged or ultra aged) and year of production (between 2013 and 2018). Gas Chromatography coupled with Mass Spectrometry was used for identification and quantification. The results showed that 65 samples (22% of the total) were phthalate free. DEP (0.13-0.27?mg/kg), BBP (0.05–2.91?mg/kg) and DINP (1.64–3.43?mg/kg) were detected in 11 (3.73%), 37 (12.54%) and 5 (1.69%) samples, respectively. But, these concentrations did not exceed the maximum permitted limits (MPL) of phthalates for alcoholic beverages. DBP (0.01–2.20?mg/kg) and DEHP (0.03–4.64?mg/kg) were detected in 96 (32.54%) and 224 (75.93%) samples, from them only 10 (3.39%) and 15 (5.08%) samples, respectively, exceeded the MPL for alcoholic beverages and they were few tequilas produced in the year 2014 or before. DEHP was the most frequent phthalate found in tequila and observed DEHP concentrations were 2-times higher in ultra aged tequilas compared to those in white tequilas. We concluded that all tequilas produced in 2015 and after, satisfied the international standards for these compounds. 相似文献
396.
397.
398.
399.
400.