全文获取类型
收费全文 | 13312篇 |
免费 | 322篇 |
国内免费 | 1177篇 |
专业分类
安全科学 | 351篇 |
废物处理 | 963篇 |
环保管理 | 1519篇 |
综合类 | 3070篇 |
基础理论 | 3679篇 |
污染及防治 | 2778篇 |
评价与监测 | 1197篇 |
社会与环境 | 1067篇 |
灾害及防治 | 187篇 |
出版年
2024年 | 7篇 |
2023年 | 60篇 |
2022年 | 203篇 |
2021年 | 200篇 |
2020年 | 207篇 |
2019年 | 152篇 |
2018年 | 1608篇 |
2017年 | 1532篇 |
2016年 | 1354篇 |
2015年 | 380篇 |
2014年 | 294篇 |
2013年 | 417篇 |
2012年 | 807篇 |
2011年 | 1687篇 |
2010年 | 973篇 |
2009年 | 821篇 |
2008年 | 1159篇 |
2007年 | 1451篇 |
2006年 | 183篇 |
2005年 | 185篇 |
2004年 | 161篇 |
2003年 | 176篇 |
2002年 | 193篇 |
2001年 | 82篇 |
2000年 | 83篇 |
1999年 | 72篇 |
1998年 | 77篇 |
1997年 | 49篇 |
1996年 | 37篇 |
1995年 | 43篇 |
1994年 | 31篇 |
1993年 | 27篇 |
1992年 | 23篇 |
1991年 | 16篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1956年 | 1篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
991.
Penggang Ren Tingting Shen Fang Wang Xing Wang Zhengwei Zhang 《Journal of Polymers and the Environment》2009,17(3):203-207
The thermoplastic starch (TPS) and nanocomposite(TPS/OMMT) was prepared with 15% carbamide, 15% ethanolamine and different
contents of organic activated montmorillonite (OMMT) by twin-screw extruder with a 130 °C barrel temperature. Fourier transforms
infrared spectroscopy and wide angle X-ray diffraction shown that the alkylamine in dodecyl benzyl dimethyl ammonium bromide
could react with MMT via cation exchange reaction. After treated, the d(001)space distance of MMT increased from 1.5 to 1.7 nm. Scanning electron microscope revealed that the lower contents of
OMMT could disperse well in the matrixes of TPS. The carbamide, ethanolamine and the OMMT could destroy the crystallization
behavior of starch, but only the OMMT restrained this behavior for long-term storing. Mechanical properties investigation
indicated that the tensile strength and modulus of TPS/OMMT nanocomposites were better than those of TPS, while the elongation
at break was descended with the increasing of OMMT contents. When the content of OMMT was 4%, the tensile strength and modulus
of TPS was improved from 4.2 and 42 MPa to 6.0 and 76 MPa, respectively. 相似文献
992.
有机酸土柱淋洗法修复重金属污染土壤 总被引:10,自引:1,他引:9
通过室内模拟实验,采用土柱淋洗方法,研究草酸、柠檬酸、乙酸和酒石酸溶液对某电镀厂附近土壤中重金属的去除效果。探讨了淋洗剂浓度、淋洗次数和淋洗时间等对淋洗效果的影响,研究草酸淋洗前后土壤中重金属形态的变化。结果表明,淋洗过程中铬的去除效果明显滞后于铜、锌和镍3种重金属离子。1 mol/L的草酸在土水比为1∶1,淋洗5h,淋洗4次的条件下可以达到最佳淋洗效果,Cu、Zn、Ni和Cr的去除率分别是99.6%、66.98%、88.7%和18.23%。 相似文献
993.
Bacterial community profiles from sediments of the Anacostia River using metabolic and molecular analyses 总被引:1,自引:0,他引:1
Bushaw-Newton KL Ewers EC Velinsky DJ Ashley JT Macavoy SE 《Environmental science and pollution research international》2012,19(4):1271-1279
Background aim and scope
Though the tidal Anacostia River, a highly polluted riverine system, has been well characterized with regard to contaminants, its overall resident bacterial populations have remained largely unknown. Improving the health of this system will rely upon enhanced understanding of the diversity and functions of these communities. Bacterial DNA was extracted from archived (AR, year 2000) and fresh sediments (RE, year 2006) collected from various locations within the Anacostia River. Using a combination of metabolic and molecular techniques, community snapshots of sediment bacterial diversity and activity were produced. 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.
Both the net primary productivity (NPP) and the normalized difference vegetation index (NDVI) are commonly used as indicators
to characterize vegetation vigor, and NDVI has been used as a surrogate estimator of NPP in some cases. To evaluate the reliability
of such surrogation, here we examined the quantitative difference between NPP and NDVI in their outcomes of vegetation vigor
assessment at a landscape scale. Using Landsat ETM+ data and a process model, the Boreal Ecosystem Productivity Simulator,
NPP distribution was mapped at a resolution of 90 m, and total NDVI during the growing season was calculated in Heihe River
Basin, Northwest China in 2002. The results from a comparison between the NPP and NDVI classification maps show that there
existed a substantial difference in terms of both area and spatial distribution between the assessment outcomes of these two
indicators, despite that they are strongly correlated. The degree of difference can be influenced by assessment schemes, as
well as the type of vegetation and ecozone. Overall, NDVI is not a good surrogate of NPP as the indicators of vegetation vigor
assessment in the study area. Nonetheless, NDVI could serve as a fairish surrogate indicator under the condition that the
target region has low vegetation cover and the assessment has relatively coarse classification schemes (i.e., the class number
is small). It is suggested that the use of NPP and NDVI should be carefully selected in landscape assessment. Their differences
need to be further evaluated across geographic areas and biomes. 相似文献
996.
Alexandros Flamos 《Environment, Development and Sustainability》2010,12(1):89-102
The (usually not professed) truth is that we are not destroying the planet due to lack of technology, but due to lack of application
of technology. Indeed, opportunities exist for renewable energy technologies’ diffusion under the new climate change regime
as they contribute to global sustainability through GHG mitigation and, they conform to national priorities by leading to
the enhancement of local economic activity, capacities and infrastructure. The clean development mechanism (CDM), although
is considered one of the global policy tools to contribute to sustainable development and technology transfer, has recently
been criticised for its unequal distribution of projects across countries and for insufficiently being embedded in developing
countries’ national energy context. In the above framework, this article presents the ENTTRANS approach, five indicative renewable
energy technologies, and insights about a more effective application of CDM, which may be part of the international process
striving towards sustainable development. 相似文献
997.
Colin Thor West 《Environment, Development and Sustainability》2011,13(1):217-235
The Arctic is a region of the world experiencing extremely rapid climatic and social change. Indigenous communities have faced
similar challenges for millennia and have historically demonstrated remarkable resilience to socioecological perturbations.
In contemporary contexts, however, it appears that the pace and extent of change is overwhelming the adaptive capacities of
many indigenous communities. Scholars recently completed a survey of living conditions spanning the circumpolar Arctic to
quantitatively document the impacts of social and ecological stress across regions. The database they created is called the
Survey of Living Conditions in the Arctic or SLiCA. This article explores the utility of using this dataset to compare livelihood
systems across three sub-regions of Alaska and four sub-regions within the Chukotka Autonomous Okrug of the Russian Federation.
The results point out that livelihood systems in Chukotka have a substantially lower level of sustainability than in Northwest
Alaska due to the high prevalence of vulnerable households. 相似文献
998.
Luca Salvati Alberto Mancini Sofia Bajocco Roberta Gemmiti Margherita Carlucci 《Regional Environmental Change》2011,11(4):767-777
In recent years, the surface area affected by land degradation (LD) has significantly increased in southern European regions
where the socioeconomic development has been proposed as a basic factor underlying the degree of vulnerability to LD. This
paper investigates the correlation between several socioeconomic indicators and the level of vulnerability to LD in Italy,
expressed as changes (1990–2000) in a composite index of land vulnerability (ΔLVI). The analysis was carried out over 784
local districts. The impact of per capita value added, agricultural intensity, industrial and tourism concentration, and urban
growth was separately tested on ΔLVI. Results indicate that a lower district value added, crop intensification, irrigation,
and the level of land vulnerability to degradation are strongly associated with the increasing level of land vulnerability
over time, highlighting the role of the socioeconomic development as a main process underlying LD. In this framework, spatially
equitable sustainable development may represent the effective strategy to mitigate the detrimental effects of economic growth
and regional disparities on Mediterranean LD. 相似文献
999.
The aim was to describe spatiotemporal patterns of colonization of spruce branches by algae and lichens and the relationship
with decreasing deposition of N and S. Coverage was estimated annually over 10 years for four Swedish Integrated Monitoring
catchments with varying deposition levels. Initial hypotheses were that algal coverage would be positively correlated with
deposition and that lichen coverage would be negatively correlated with S and positively with N deposition. Data were analyzed
using regression, ANOVA, and partial least square regression. The results showed a temporal decrease in the coverage of algae
but an increase in colonization rates, while lichens showed less uniform patterns. Within catchments, algae and lichen coverages
were positively correlated with mainly S deposition. Across catchments, coverage of algae increased, while the coverage of
lichens decreased with increasing N and S deposition. Colonization rates of both algae and lichens showed weak correlations
with both spatial and temporal trends in N and S deposition. Thus, while N and S deposition had an effect on the colonization
and coverage of algae and lichens, other factors are also important. 相似文献
1000.
A sensitive spectrophotometric method has been developed for determination of ametryn in agricultural samples. The proposed
method was based on reaction with pyridine and further coupling with sulfanilic acid to form a colored product. The absorbance
was measured at 400 nm with a molar absorptivity of 2.1 × 105 L mol−1 cm−1. The method shows a linear range from 0.2–20 μg mL−1 with limit of detection and limit of quantification 0.16 and 0.54 μg mL−1, respectively. The method has been successfully applied to the determination of ametryn in sugarcane juice and commercial
formulations after separation of ametryn from triazine herbicides based on solvent extraction. Recovery values were found
to be in the range of 96.0 ± 0.2% to 98.4 ± 0.1%. 相似文献