全文获取类型
收费全文 | 11497篇 |
免费 | 725篇 |
国内免费 | 3839篇 |
专业分类
安全科学 | 916篇 |
废物处理 | 627篇 |
环保管理 | 892篇 |
综合类 | 6560篇 |
基础理论 | 1856篇 |
污染及防治 | 3697篇 |
评价与监测 | 541篇 |
社会与环境 | 519篇 |
灾害及防治 | 453篇 |
出版年
2024年 | 35篇 |
2023年 | 229篇 |
2022年 | 615篇 |
2021年 | 552篇 |
2020年 | 450篇 |
2019年 | 411篇 |
2018年 | 415篇 |
2017年 | 540篇 |
2016年 | 534篇 |
2015年 | 582篇 |
2014年 | 836篇 |
2013年 | 1100篇 |
2012年 | 973篇 |
2011年 | 1019篇 |
2010年 | 798篇 |
2009年 | 734篇 |
2008年 | 865篇 |
2007年 | 692篇 |
2006年 | 651篇 |
2005年 | 472篇 |
2004年 | 352篇 |
2003年 | 390篇 |
2002年 | 363篇 |
2001年 | 274篇 |
2000年 | 322篇 |
1999年 | 328篇 |
1998年 | 257篇 |
1997年 | 243篇 |
1996年 | 210篇 |
1995年 | 175篇 |
1994年 | 129篇 |
1993年 | 128篇 |
1992年 | 111篇 |
1991年 | 88篇 |
1990年 | 39篇 |
1989年 | 35篇 |
1988年 | 28篇 |
1987年 | 17篇 |
1986年 | 15篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Comparative assessments of VOC emission rates and associated health risks from wastewater treatment processes 总被引:1,自引:0,他引:1
WB Yang WH Chen CS Yuan JC Yang QL Zhao 《Journal of environmental monitoring : JEM》2012,14(9):2464-2474
With the growing concern regarding emission of volatile organic compounds (VOCs) from wastewater treatment plants (WWTPs), the relationship between the VOC emission rates and the associated public health risks has been rarely discussed. The objective of this study was to examine and compare the VOC emission rates and cancer and non-cancer risks by inhalation intake, using a municipal WWTP in China as an example, with respect to the effects of treatment technologies, VOC species, and seasonal variation. Given the treatment technology considered, the emission rates of VOCs in this study were estimated by means of mass balance or calculated on the molecular level. From the viewpoints of both emission rates and cancer and non-cancer risks, sedimentation was the treatment technology with the highest health risks to the workers. Slightly lower VOC emission rates and health risks than those for sedimentation were observed in anaerobic treatment. Although the aeration significantly enhanced the VOC emission rates in the aerobic treatment process, the associated health risks were limited due to the low VOC concentrations in the gas phase, which were likely attributed to the strong mixing and dilution with fresh air by aeration. Amongst the VOCs investigated, benzene was the VOC with both a relatively high emission rate and health risk, while trichloroethylene possessed a high emission rate but the lowest health risk. Without strong interfacial aeration and turbulence between the water and atmosphere, the effects of treatment technology and seasonal variation on the health risks might be connected to the VOC emission rates, while the effect of VOC species depended considerably on the respective cancer slope factors and reference concentrations; the employment of aeration provided a different conclusion in which the emission rates were enhanced without a significant increase in the related cancer risks. These findings can provide insight into future health risk management and reduction strategies for workers in WWTPs. 相似文献
912.
Characteristic, composition, and sources of TSP investigated by HRTEM/EDS and ESEM/EDS 总被引:1,自引:0,他引:1
Zhai Y Fu Z Wang L Zeng G Li C Chen H Lan Y Lu P 《Environmental monitoring and assessment》2012,184(11):6693-6707
Total suspended particle (TSP) collected at the fifth floor of House Dust in Hunan University, China, was analyzed in terms of microscopic morphology and chemical composition. The fine particles (50?nm-2?μm) in the TSP were analyzed by a high-resolution transmission electron microscope equipped with an energy-dispersive X-ray analyzer (HRTEM/EDS). Results showed that the particles were in shapes of plate, irregular and agglomerate. Based on EDS results, these fine particulate matter was primarily composed of Fe-rich (35.82-61.29%), Ca-rich (30.18-36.77%) and Si-rich (18.95-32.28%) particles. Other elements mainly including Mg (0.47-4.97%), Al (0.45-14.57%), S (0.45-4.73%), K (1.13-2.13%) and Zn (0.67-3.85%) were also observed. The sources analysis indicated that the HRTEM particles mainly originated from coal combustion, traffic emission, vehicles exhaust emission and fugitive soil or cement particulate matter. The coarse particles (4-50?μm) were detected by environmental scanning electron microscopy coupled with energy-dispersive X-ray detector (ESEM/EDS). Based on a simple algorithm, ESEM particles were categorized into five groups: C-bearing (46.15%, 67% and 86.98%), Si + Ca-bearing (21.48?+?11.80%, 16.51?+?10.81% and 16.32?+?10.62%), Si + Al-bearing (20.06?+?12.40%, 20.16?+?11.22% and 15.31?+?11.25%), Si-bearing (34.40%, 26.92% and 27.15%) particles and aggregates, most of which exhibit obvious crystalline structure, and these ESEM particles mainly derived from vehicles exhaust emission, coal combustion, soil, and biomass burning, while the aggregates are indicative of atmospheric reaction progress. HRTEM/EDS and ESEM/EDS are mutual complementary in analyzing the characteristic and determining the sources of TSP. 相似文献
913.
Discharge measurement in a tidal stream is always a difficult task. Owing to the complex flow conditions, discharge measurement in tidal streams has to be finished quickly, and must be highly efficient in order to yield an accurate measurement of real-time discharge. Measuring the discharge of tidal streams is done in three steps: (1) establishing the stage and cross-sectional area relation, (2) estimating the index velocity by using a velocity distribution equation based on the probability concept, (3) establishing the relationship between the index and mean velocities. Then the cross-sectional area and mean velocity can be estimated by the gage height and index velocity, respectively. The discharge of tidal streams is computed as the product of the cross-sectional area and mean velocity. The velocity distribution of the Taipei Bridge and Guan-du Bridge in the Tanshui River were established and analyzed to demonstrate the use of discharge measurement by index velocity for estimating the discharge of this tidal stream. The results reveal no large difference between the discharges measured by the conventional methods and the index velocity. This pilot study proposed a cost-effectiveness and efficient method. It is an easy, quick, and accurate model for measuring the real-time discharge of a tidal stream. It makes automatic, real-time, and continuous monitoring of the discharge in a tidal stream become possible. 相似文献
914.
Yen-Chang Chen Jih-Hung Liu Jan-Tai Kuo Cheng-Fang Lin 《Environmental monitoring and assessment》2013,185(7):5653-5672
Reservoirs in Taiwan are inundated with nutrients that result in algal growth, and thus also reservoir eutrophication. Controlling the phosphorus load has always been the most crucial issue for maintaining reservoir water quality. Numerous agricultural activities, especially the production of tea in riparian areas, are conducted in watersheds in Taiwan. Nutrients from such activities, including phosphorus, are typically flushed into rivers during flooding, when over 90 % of the yearly total amount of phosphorous enters reservoirs. Excessive or enhanced soil erosion from rainstorms can dramatically increase the river sediment load and the amount of particulate phosphorus flushed into rivers. When flow rates are high, particulate phosphorus is the dominant form of phosphorus, but sediment and discharge measurements are difficult during flooding, which makes estimating phosphorus flux in rivers difficult. This study determines total amounts of phosphorus transport by measuring flood discharge and phosphorous levels during flooding. Changes in particulate phosphorus, dissolved phosphorus, and their adsorption behavior during a 24-h period are analyzed owing to the fact that the time for particulate phosphorus adsorption and desorption approaching equilibrium is about 16 h. Erosion of the reservoir watershed was caused by adsorption and desorption of suspended solids in the river, a process which can be summarily described using the Lagmuir isotherm. A method for estimating the phosphorus flux in the Daiyujay Creek during Typhoon Bilis in 2006 is presented in this study. Both sediment and phosphorus are affected by the drastic discharge during flooding. Water quality data were collected during two flood events, flood in June 9, 2006 and Typhoon Bilis, to show the concentrations of suspended solids and total phosphorus during floods are much higher than normal stages. Therefore, the drastic changes of total phosphorus, particulate phosphorus, and dissolved phosphorus in rivers during flooding should be monitored to evaluate the loading of phosphorus more precisely. The results show that monitoring and controlling phosphorus transport during flooding can help prevent the eutrophication of a reservoir. 相似文献
915.
Odor and corrosion are common problems in domestic wastewater collection, transportation, pumping, and treatment processes. Based on the comparison among odorous compounds and onsite observations at a wastewater lift station, H2S is more likely to have caused the odor and corrosion problems than methanethiol and other organic sulfides. The field data from both air and wastewater quality monitoring demonstrated that more H2S (1 ppmv) was formed at a more negative redox potential, lower pH, and a higher temperature of wastewater. Since the lower detection level of most current analytical techniques is much greater than human’s smell and the reference concentration for adverse health effects, automatic monitoring on the threshold of H2S formation provides a mechanism to trigger control techniques only when necessary for cost saving purposes. Based on Gibbs free energy, a more negative redox potential is required to form H2S with an increase in pH and a decrease in temperature and SO 4 2? concentration. However, pH effect is more significant than both temperature and SO 4 2? concentration for H2S formation. It is recommended that H2S control techniques be started when the redox potential is below ?44 mV, the pH is lower than 5.6, and the temperature is higher than 11.5 °C to control H2S below the reference concentration. Corroded concrete particles were examined by X-ray diffraction, which showed that the dominant crystal form was quartz. 相似文献
916.
Land use change and landslide characteristics analysis for community-based disaster mitigation 总被引:1,自引:0,他引:1
On August 8, 2009, Typhoon Morakot brought heavy rain to Taiwan, causing numerous landslides and debris flows in the Taihe village area of Meishan Township, Chiayi County, in south-central Taiwan. In the Taihe land is primary used for agriculture and land use management may be a factor in the area’s landslides. This study explores Typhoon Morakot-induced landslides and land use changes between 1999 and 2009 using GIS with the aid of field investigation. Spot 5 satellite images with a resolution of 2.5 m are used for landslide interpretation and manually digitalized in GIS. A statistical analysis for landslide frequency–area distribution was used to identify the landslide characteristics associated with different types of land use. There were 243 landslides with a total area of 2.75 km2 in the study area. The area is located in intrinsically fragile combinations of sandstone and shale. Typhoon Morakot-induced landslides show a power–law distribution in the study area. Landslides were mainly located in steep slope areas containing natural forest and in areas planted with bamboo, tea, and betel nut. Land covered with natural forest shows the highest landslide ratio, followed by bamboo, betel nut, and tea. Landslides thus show a higher ratio in areas planted with shallow root vegetation such as bamboo, betel nut, and tea. Furthermore, the degree of basin development is proportional to the landslide ratio. The results show that a change in vegetation cover results in a modified landslide area and frequency and changed land use areas have higher landslide ratios than non-changed. Land use management and community-based disaster prevention are needed in mountainous areas of Taiwan for hazard mitigation. 相似文献
917.
Tao Y Yao S Xue B Deng J Wang X Feng M Hu W 《Journal of environmental monitoring : JEM》2010,12(12):2282-2289
Sources, partitioning and toxicological risk of 15 priority polycyclic aromatic hydrocarbons (PAHs) in surface sediments from drinking water sources of Taihu Lake, with an area of 2428 km(2) located in the most developed and populated area of China, were studied, and the results were compared with those in other lakes of China and the USA. Concentrations of the 15 PAHs in sediments ranged from 436.6 to 1334.9 ng g(-1) (dw). Gasoline combustion, coal combustion, diesel combustion from shipping and spillage of petroleum were apportioned to be the main sources of PAHs in this area by principal component analysis, which contributed 35.19%, 26.43%, 25.41% and 12.97% to the PAH sources estimated by further multiple linear regression. Levels of PAHs in sediments were negatively correlated with contents of clay and fine silt (<16 μm), while positively with contents of medium silt, coarse silt and sand (>16 μm). Humin with size larger than 16 μm contained the largest part of the burden of PAHs in sediments, but the specific partitioning domain (bound humic acid, lipid or insoluble residue) depended on properties of organic matter reflected by optical absorbance at 465 and 665 nm. Total toxic benzo[a]pyrene equivalent (TEQ(carc)) of the carcinogenic PAHs in sediments varied from 31.8 to 209.3 ngTEQ(carc) g(-1). Benzo[a]pyrene and dibenzo[a,h]anthracene contributed 45.36 and 25.31% to total TEQ(carc), posing high toxicological risk to this area. 相似文献
918.
集合数值预报系统在上海市空气质量预测预报中的应用研究 总被引:17,自引:0,他引:17
王茜伏晴艳王自发王体健刘萍陆涛林陈渊段玉森黄嫣旻 《环境监控与预警》2010,2(4):1-6
介绍了上海市世博环境空气质量集合数值预报系统的框架,分析了各模式在上海市空气质量预报及排放源污染贡献测算中的应用情况,提出开发多种预报手段、实施集合预报是提高城市空气质量预报准确率的发展方向。 相似文献
919.
Kao PM Hsu BM Chen NH Huang KH Huang CC Ji DD Chen JS Lin WC Huang SW Chiu YC 《Environmental monitoring and assessment》2012,184(7):4335-4344
The protistan genus Acanthamoeba is a free-living amoeba existing in various environments. Within this protistan genus, there are some species recognized as potential human pathogens, which may cause granulomatous amoebic encephalitis, Acanthamoeba keratitis and chronic granulomatous lesions of the skin. In this study, 211 water samples were collected from two watersheds in southern Taiwan. We detected Acanthamoeba based on the PCR amplification with a genus-specific primer pair and investigation of Acanthamoeba in Puzih River and Kaoping River in southern Taiwan. Acanthamoeba species were detected in 34 (16.1%) samples. The presence or absence of Acanthamoeba within the water samples showed significant difference with the levels of water temperature and total coliforms. The most frequently identified Acanthamoeba genotype was T4 (n = 19), followed by T5 (n = 8), and then T15 (n = 3). Genotype T6, T7/T8, T11 and T12 were all detected once. Genotype T4, T5, T6, T11 and T15 of Acanthamoeba are responsible for Acanthamoeba keratitis and should be considered a potential health threat associated with human activities in environmental surface water watersheds. 相似文献
920.