全文获取类型
收费全文 | 15874篇 |
免费 | 657篇 |
国内免费 | 2117篇 |
专业分类
安全科学 | 661篇 |
废物处理 | 975篇 |
环保管理 | 1766篇 |
综合类 | 5351篇 |
基础理论 | 4029篇 |
污染及防治 | 2971篇 |
评价与监测 | 1418篇 |
社会与环境 | 1228篇 |
灾害及防治 | 249篇 |
出版年
2024年 | 39篇 |
2023年 | 166篇 |
2022年 | 354篇 |
2021年 | 340篇 |
2020年 | 338篇 |
2019年 | 262篇 |
2018年 | 1732篇 |
2017年 | 1724篇 |
2016年 | 1488篇 |
2015年 | 502篇 |
2014年 | 429篇 |
2013年 | 545篇 |
2012年 | 983篇 |
2011年 | 1932篇 |
2010年 | 1190篇 |
2009年 | 1057篇 |
2008年 | 1359篇 |
2007年 | 1654篇 |
2006年 | 395篇 |
2005年 | 334篇 |
2004年 | 265篇 |
2003年 | 284篇 |
2002年 | 305篇 |
2001年 | 190篇 |
2000年 | 177篇 |
1999年 | 129篇 |
1998年 | 101篇 |
1997年 | 71篇 |
1996年 | 56篇 |
1995年 | 64篇 |
1994年 | 36篇 |
1993年 | 31篇 |
1992年 | 24篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1972年 | 1篇 |
1964年 | 1篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Chen B Pan Y Wang J Fu Z Zhang Y Zhou Y 《Environmental monitoring and assessment》2012,184(6):3545-3556
Evenly distributed sampling design is generally considered as an efficient sampling design. It is widely used in sampling
for the environmental survey. In this paper, we present a novel method for generating N evenly distributed samples within a given irregular polygon via simulating the movements of some ideal homogeneous point
charges. Initially, charges are randomly put into the sampling region; then, they are freed and held orderly; and after enough
runs, the charges will finally reach a stable state with all of them having a zero resultant force and velocity; and so they
distribute evenly within the region. Their layout can thus be considered as an evenly distributed sampling design. The main
advantages of this method are: (1) it is easy to understand and implement; (2) it is efficient in both running and generating
better designs. Analysis and experimental results indicate that this method is an efficient and robust method for generating
even sampling designs for 2D polygonal sampling region. 相似文献
993.
The objective of this study is to assess the risk of insufficient water supply posed by high-turbidity water. Several phenomena
can pose risks to the sufficiency of a water supply; this study concerns risks to water treatment plants from particular properties
of rainfall and raw water turbidity. High-turbidity water can impede water treatment plant operations; rainfall properties
can influence the degree of soil erosion. Thus, water turbidity relates to rainfall characteristics. Exceedance probabilities
are presented for different rainfall intensities and turbidities of water. When the turbidity of raw water is higher than
5,000 NTU, it can cause operational problems for a water treatment plant. Calculations show that the turbidity of raw water
at the Ban-Sin water treatment plant will be higher than 5,000 NTU if the rainfall intensity is larger than 165 mm/day. The
exceedance probability of high turbidity (turbidity >5,000 NTU) in the Ban-Sin water treatment plant is larger than 10%. When
any water treatment plant cannot work regularly, its ability to supply water to its customers is at risk. 相似文献
994.
Sakizadeh M Esmaeili Sari A Abdoli A Bahramifar N Hashemi SH 《Environmental monitoring and assessment》2012,184(5):3231-3237
The Anzali Wetland is one of the most important ecosystems in the north of Iran, and parts of it were registered as a Ramsar
site in 1975. However, even though, due to many problems, including eutrophication produced by inflow of excess nutrients
and organic materials, the wetland was also listed on the Montreux Record indicating the need to take urgent remedial action.
This study was conducted to study the levels of polychlorinated biphenyls (PCBs) and total mercury (THg) in two fish species
(Esox lucius and Carassius auratus) as bio-indicators of the ecosystem condition in eastern part of Anzali Wetland. The sampling was carried out in six different
periods between years 2009 and 2010. The results showed that the amounts of PCBs in the muscle of northern pike were below
the detection limit of gas chromatography, whereas the average concentration in goldfish was 0.449 mg/kg wet weight. Some
possible reasons for the higher levels of PCBs in goldfish in comparison with pike have been discussed. No significant (p < 0.05) correlation was observed between PCBs and biological factors (weight, length, lipid content) for both species. On
the other hand, the mean concentration of THg in the muscle of pike and goldfish were 182.22 and 75.27 ng/g dry weight, respectively.
Although these concentrations were below US-EPA criterion for human consumption (0.3 mg/kg), it pointed up a significant deterioration
of the ecosystem condition during the past years. Finally, statistical analysis revealed a significant correlation between
THg with weight and an insignificant correlation with length for pike specimens. 相似文献
995.
Simulation of soil loss processes based on rainfall runoff and the time factor of governance in the Jialing River Watershed,China 总被引:1,自引:0,他引:1
Jialing River is the largest tributary in the catchment area of Three Gorges Reservoir, and it is also one of the important
areas of sediment yield in the upper reaches of the Yangtze River. In recent years, significant changes of water and sediment
characteristics have taken place. The "Long Control" Project implemented since 1989 had greatly changed the surface appearance
of the Jialing River Watershed (JRW), and it had made the environments of the watershed sediment yield and sediment transport
change significantly. In this research, the Revised Universal Soil Loss Equation was selected and used to predict the annual
average amount of soil erosion for the special water and sediment environments in the JRW after the implementation of the
"Long Control" Project, and then the rainfall–runoff modulus and the time factor of governance were both considered as dynamic
factors, the dynamic sediment transport model was built for soil erosion monitoring and forecasting based on the average sediment
yield model. According to the dynamic model, the spatial and temporal distribution of soil erosion amount and sediment transport
amount of the JRW from 1990 to 2007 was simulated using geographic information system (GIS) technology and space-grid algorithm.
Simulation results showed that the average relative error of sediment transport was less than 10% except for the extreme hydrological
year. The relationship between water and sediment from 1990 to 2007 showed that sediment interception effects of the soil
and water conservation projects were obvious: the annual average sediment discharge reduced from 145.3 to 35 million tons,
the decrement of sediment amount was about 111 million tons, and decreasing amplitude was 76%; the sediment concentration
was also decreased from 2.01 to 0.578 kg/m3. These data are of great significance for the prediction and estimation of the future changing trends of sediment storage
in the Three Gorges Reservoir and the particulate non-point source pollution load carried by sediment transport from watershed
surface. 相似文献
996.
Gas–particle concentration,distribution, and health risk assessment of polycyclic aromatic hydrocarbons at a traffic area of Giza,Egypt 总被引:1,自引:0,他引:1
Atmospheric particulate and gaseous polycyclic aromatic hydrocarbons (PAHs) samples were collected from an urban area in Dokki
(Giza) during the summer of 2007 and the winter of 2007–2008. The average concentrations of PAHs were 1,429.74 ng/m3 in the particulate phase, 2,912.56 ng/m3 in the gaseous phase, and 4,342.30 ng/m3 in the particulate + gaseous phases during the period of study. Dokki has high level concentrations of PAH compounds compared
with many polluted cities in the world. The concentrations of PAH compounds in the particulate and gaseous phases were higher
in the winter and lower in the summer. Total concentrations of PAHs in the particulate phase and gaseous phase were 22.58%
and 77.42% in summer and 36.97% and 63.03% in winter of the total (particulate + gaseous) concentrations of PAHs, respectively.
The gaseous/particulate ratios of PAHs concentration were 3.43 in summer and 1.71 in winter. Significant negative correlation
coefficients were found between the ambient temperature and concentrations of the total PAHs in the particulate and gaseous
phases. The distribution of individual PAHs and different categories of PAHs based on aromatic ring number in the particulate
and gaseous phases during the summer and winter were nearly similar, indicating similar emission sources of PAHs in both two
seasons. Benzo(b)fluoranthene in the particulate phase and naphthalene in the gaseous phase were the most abundant compounds. Diagnostic concentration
ratios of PAH compounds indicate that these compounds are emitted mainly from pyrogenic sources, mainly local vehicular exhaust
emissions. Health risks associated with the inhalation of individual PAHs in particulate and gaseous phases were assessed
on the basis of its benzo(a)pyrene equivalent concentration. Dibenzo(a,h)anthracene and benzo(a)pyrene in the particulate phase and benzo(a)pyrene and benzo(a)anthracene in the gaseous phase were the greatest contributors to the total health risks. The relative mean contributions
of the total carcinogenic activity (concentrations) of all PAHs to the total concentrations of PAHs were 29.37% and 25.15%
in the particulate phase and 0.76% and 0.92% in the gaseous phase during the summer and winter, respectively. These results
suggest that PAHs in the particulate phase in the ambient air of Dokki may pose a potential health risk. 相似文献
997.
Ilijević K Gržetić I Živadinov I Popović A 《Environmental monitoring and assessment》2012,184(5):2805-2828
Seasonal spatial and temporal changes of selected eco-chemical parameters in section of the Danube River flowing through Serbia
were analyzed. Data for electrical conductivity (EC), dry and suspended matter, residue on ignition, chemical oxygen demand
(COD), biochemical oxygen demand (BOD-5), ultraviolet extinction, dissolved oxygen (DO), oxygen saturation, pH, nitrates,
total phosphorus, and nitrogen were collected between 1992 and 2006. The use of monthly medians combined with linear regression
and two-sided t test has been proven to be the best approach for resolving trends from natural variability of investigated parameters and
for determining trend significance. Patterns of temporal changes between different months were examined. It was also determined
that spatial trends of some parameters oscillate in predictable manner, increasing in one part of the year and declining in
the other. Regression slope coefficients, an excellent indicator for determining when the water quality is changing the most
along the course of the Danube, reach their maximum during summer for temperature (t), electric conductivity, nitrates, and total N, while in the same season suspended matter, COD, BOD-5, DO, and oxygen saturation
coefficients reach their minimum. Correlations for used data sets of selected parameters were analyzed for better understanding
of their behavior and mutual relations. It was observed that as Danube flows through Serbia, its general eco-chemical status
either stagnates or improves, but the rate of river self-purification often depends on the season of the year. 相似文献
998.
Lan Q Cui K Zeng F Zhu F Liu H Chen H Ma Y Wen J Luan T Sun G Zeng Z 《Environmental monitoring and assessment》2012,184(8):4921-4929
Phthalate esters (PAEs) were examined in indoor and outdoor dust samples from the subtropical city of Guangzhou, China. The ∑(16)PAEs concentrations ranged from 121 to 3,223 μg g(-1) dust, with the median concentration of 840 μg g(-1) dust. Significantly higher concentrations of PAEs in dust samples were found in offices where electrical and electronic devices, carpet pads, and office furniture were widely used. Of the 16 PAEs, diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and di(2-ethylhexyl) phthalate (DEHP) dominated the PAEs in indoor and outdoor dust samples, and accounted for >96.8% and >93.1% of the ∑(16)PAEs concentrations, respectively. The median daily inhalation exposure of ∑(16)PAEs were 3.53 and 0.247 μg kg(-1) body weight day(-1), and at the 95(th) percentile were 7.62 and 0.530 μg kg(-1) body weight day(-1), up on the measured concentrations and estimated dust ingestion rates, respectively, for toddles and adults. The ubiquitous distribution of PAEs as noted in this study suggests the need for detailed assessment of PAEs concentrations using more sites and to further investigate the factors influencing PAEs exposure in China. 相似文献
999.
Kim NS Sakong J Choi JW Hong YS Moon JD Lee BK 《Environmental monitoring and assessment》2012,184(7):4139-4149
In 2007, as part of the control and prevention of environmental contamination threatening public health, the Korean Ministry of Environment planned to implement a national biomonitoring survey of three metals: lead, cadmium, and mercury in the blood of residents living near 350 abandoned metal mines known to be contaminated and as possible threats to the health of inhabitants. Thus, we investigated demographic and lifestyle variables and blood lead levels in residents living around the mines and compared them against those of control subjects. We measured the blood lead concentrations in 14,849 subjects (14,132 from nearby the 350 abandoned metal mines and 717 subjects from eight control areas). A questionnaire was provided to all subjects to determine gender, age, mining experience, period of time living in the vicinity of mines, smoking status, and personal perception of abandoned mines as a health risk. The geometric means (95% confidence intervals) of the blood lead levels of residents living around the abandoned metal mines and control areas were 3.017 (2.996-3.037 μg/dL) [female, 2.797 μg/dL (2.771-2.822 μg/dL); male, 3.330 μg/dL (3.298-3.363 μg/dL)] and 2.757 (2.677-2.837 μg/dL) [female, 2.604 μg/dL (2.506-2.700 μg/dL); male, 2.993 μg/dL (2.859-3.126 μg/dL)], respectively. Among residents of the mining areas, nonsmokers and residents who had no mining experience showed significantly lower mean blood lead levels than did smokers, past smokers, and those with mining experience. The mean blood lead concentrations of residents who expressed some concern about the abandoned mines were significantly higher than those of residents without concerns. The mean blood lead concentration of residents living around the abandoned mines was significantly higher than that of residents living in control areas as well as that of the general adult Korean population. We also confirmed that smoking is an important variable to consider, as it increases blood lead concentration. 相似文献
1000.
通过对惠州市电子废弃物收集体系组成、去向以及电子废弃物处置方式的调查,分析惠州市电子废弃物收集和处置存在的一系列问题,结合实际提出了城市电子废弃物资源化管理模式的初步构想。 相似文献