全文获取类型
收费全文 | 4747篇 |
免费 | 408篇 |
国内免费 | 1429篇 |
专业分类
安全科学 | 75篇 |
废物处理 | 4篇 |
环保管理 | 827篇 |
综合类 | 3410篇 |
基础理论 | 615篇 |
环境理论 | 1篇 |
污染及防治 | 276篇 |
评价与监测 | 368篇 |
社会与环境 | 809篇 |
灾害及防治 | 199篇 |
出版年
2024年 | 45篇 |
2023年 | 132篇 |
2022年 | 250篇 |
2021年 | 235篇 |
2020年 | 234篇 |
2019年 | 216篇 |
2018年 | 202篇 |
2017年 | 222篇 |
2016年 | 274篇 |
2015年 | 321篇 |
2014年 | 244篇 |
2013年 | 338篇 |
2012年 | 364篇 |
2011年 | 391篇 |
2010年 | 264篇 |
2009年 | 282篇 |
2008年 | 252篇 |
2007年 | 299篇 |
2006年 | 313篇 |
2005年 | 253篇 |
2004年 | 195篇 |
2003年 | 153篇 |
2002年 | 162篇 |
2001年 | 134篇 |
2000年 | 135篇 |
1999年 | 118篇 |
1998年 | 80篇 |
1997年 | 76篇 |
1996年 | 53篇 |
1995年 | 62篇 |
1994年 | 50篇 |
1993年 | 35篇 |
1992年 | 26篇 |
1991年 | 22篇 |
1990年 | 21篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 6篇 |
排序方式: 共有6584条查询结果,搜索用时 46 毫秒
211.
Physico-chemical characteristics of some river and hand-dug well waters used for drinking and domestic purposes in the oil
rich Niger Delta area of Nigeria were assessed using standard methods. The concentrations of the parameters in the river water
samples ranged in the following order: pH (5.6–6.9), temperature (26.90–28.60°C), turbidity (23–63 NTU), electrical conductivity
(52–184 μs/cm), DO (5.4–7.2 mg/l), BOD (21–57 mg/l), TDS (6.0–217 mg/l), PO4
3− (0.19–1.72 mg/l), SO4
2− (25–36.8 mg/l), NO3
− (20.3–28 mg/l), Fe (6.07–15.71 mg/l), Zn (0.04–0.24 mg/l), Pb (0.01–0.17 mg/l), Ni (0.01–0.13 mg/l), Vn (0.01–0.20 mg/l)
and Hg (0.001–0.002 mg/l). The concentrations of these parameters in the hand-dug well water ranged in the following order:
pH (5.7–6.8) temperature (26–30°C), turbidity (134–171 NTU), electrical conductivity (160–340 μs/cm), DO (5.4–6.4 mg/l), BOD
(13–34 mg/l), TDS (110–190 mg/l), PO4
3− (0.84–1.84 mg/l), SO4
2− (10.6–28.1 mg/l), NO3
− (11.3–23 mg/l), Fe (13.17–16.31 mg/l), Ni (0.01–0.02 mg/l), Vn (0.01–0.04 mg/l) and Hg (0.001–0.004 mg/l). The concentrations
of BOD, turbidity, NO3
− and Fe in the water samples were above WHO and FMENV permissible limits for safe drinking water. The results suggest that
the use of such waters for drinking and domestic purposes pose a serious threat to the health of the users and calls for the
intervention of government agencies. 相似文献
212.
Bolca M Turkyilmaz B Kurucu Y Altinbas U Esetlili MT Gulgun B 《Environmental monitoring and assessment》2007,131(1-3):409-419
Because of their intense vegetation and the fact that they include areas of coastline, deltas situated in the vicinity of big cities are areas of greet attraction for people who wish to get away from in a crowded city. However, deltas, with their fertile soil and unique flora and fauna, need to be protected. In order for the use of such areas to be planned in a sustainable way by local authorities, there is a need for detailed data about these regions. In this study, the changes in land use of the Balçova Delta, which is to the immediate west of Turkey’s third largest city Izmir, from 1957 up to the present day, were investigated. In the study, using aerial photographs taken in 1957, 1976 and 1995 and an IKONOS satellite image from the year 2005, the natural and cultural characteristics of the region and changes in the coastline were determined spatially. Through this study, which aimed to reveal the characteristics of the areas of land already lost as well as the types of land use in the Balçova delta and to determine geographically the remaining areas in need of protection, local authorities were provided with the required data support. Balçova consists of flat and fertile wetland with mainly citrus-fruit orchards and flower-producing green houses. The marsh and lagoon system situated in the coastal areas of the delta provides a habitat for wild life, in particular birds. In the Balçova Delta, which provides feeding and resting for migratory birds, freshwater sources are of vital importance for fauna and flora. The settlement area, which in 1957 was 182 ha, increased 11-fold up to the year 2005 when it reached 2,141 ha. On the other hand, great losses were determined in farming land, olive groves, forest and in the marsh and lagoon system. This unsystematic and rapid urbanization occurring in the study region is not only causing the loss of important agricultural land and wetland, but also lasting water and soil pollution. 相似文献
213.
During the second half of the 20th century, the Ganga River ecosystem has been continuously altered by several ongoing anthropogenic
processes, accommodating multi-dimensional pressure due to increase of nearly four-fold human population. For solution of
any environmental issues of the river, the Earth System Science approach is required to have maximum socio-economic benefits
to millions of people living in Indian and Bangladesh. A bibliography containing more than 250 references on environmental
studies of the Ganga River was prepared to preserve its ecosystem by providing the baseline support in this regard. 相似文献
214.
Kuang YW Zhou GY Da Wen Z Liu SZ 《Environmental science and pollution research international》2007,14(4):270-275
Goal, Scope and Background Rapid urbanization and the expansion of industrial activities in the past several decades have led to large increases in emissions
of pollutants in the Pearl River Delta of south China. Recent reports have suggested that industrial emission is a major factor
contributing to the damages in current natural ecosystem in the Delta area. Tree barks have been used successfully to monitor
the levels of atmospheric metal deposition in many areas, but rarely in China. This study aimed at determining whether atmospheric
heavy metal deposition from a Pb-Zn smeltery at Qujiang, Guangdong province, could be accurately reflected both in the inner
bark and the outer bark of Masson pine (Pinus massoniana L.). The impact of the emission from smeltery on the soils beneath the trees and the relationships of the concentrations
between the soils and the barks were also analyzed.
Methods Barks around the bole of Pinus massoniana from a pine forest near a Pb-Zn smeltery at Qujiang and a reference forest at Dinghushan natural reserve were sampled with
a stainless knife at an average height of 1.5 m above the ground. Mosses and lichens on the surface barks were cleaned prior
to sampling. The samples were carefully divided into the inner bark (living part) and the outer bark (dead part) in the laboratory,
and dried and ground, respectively. After being dry-ashed, the powder of the barks was dissolved in HNO3. The solutions were analyzed for iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni) and cobalt
(Co) by inductively coupled plasmas emission spectrometry (ICP, PS-1000AT, USA) and Cadmium (Cd) and lead (Pb) by graphite
furnace atomic absorption spectrometry (GFAAS, ZEENIT 60, Germany). Surface soils (0–10 cm) beneath the sample trees were
also collected and analyzed for the selected metals.
Results and Discussion Concentrations of the selected metals in soils at Qujiang were far above their environmental background values in the area,
except for Fe and Mn, whilst at Dinghushan, they were far below their background values, except for Cd and Co. Levels of the
metals, in particular Pb and Zn, in the soils beneath the sample trees at Qujiang were higher than those at Dinghushan with
statistical significance. The result suggested that the pine forest soils at Qujiang had a great input of heavy metals from
wet and dry atmospheric deposition, with the Pb-Zn smeltery most probably being the source.
Levels of Cu, Fe, Mn, Zn, Ni and Pb at Qujiang, both in the inner and the outer bark, were statistically higher than those
at Dinghushan. Higher concentrations of Pb, Fe, Zn and Cu may come from the stem-flow of elements leached from the canopy,
soil splash on the 1.5 m height and sorption of metals in the mosses and lichens growing on the bark, which were direct or
indirect results from the atmospheric deposition. Levels of heavy metals in the outer barks were associated well with the
metal concentrations in the soil, reflecting the close relationships between the metal atmospheric deposition and their accumulation
in the outer bark of Masson pine. The significant (p<0.01) correlations of Fe-Cu, Fe-Cr, Fe-Pb, Fe-Ni, Pb-Ni, and Pb-Zn in
the outer barks at Qujiang again suggested a common source for the metals. The correlation only occurred between Pb and Ni,
Cd and Co in the outer barks at Dinghushan, which suggested that those metals must possibly have other uncommon sources.
Conclusions Atmospheric deposition of the selected metals was great at Qujiang, based on the levels in the bark of Pinus massoniana and on the concentrations in the soils beneath the trees compared with that at Dinghushan. Bark of Pinus massoniana, especially the outer bark, was an indicator of metal loading at least at the time of sampling.
Recommendations and Perspectives The results from this study and the techniques employed constituted a new contribution to the development of biogeochemical
methods for environmental monitoring particularly in areas with high frequency of pollution in China. The method would be
of value for follow up studies aimed at the assessment of industrial pollution in other areas similar with the Pearl River
Delta. 相似文献
215.
Passy SI 《Environmental monitoring and assessment》2007,127(1-3):409-417
Diatom assemblages from 83 epilithic samples taken from the Mesta River, Bulgaria, were regressed against three sets of predictor
variables, i.e. environmental, spatial, and temporal. Redundancy analysis (RDA) of species and environmental data explained
36% of the diatom variance and extracted several important gradients of species distribution, associated with a downstream
increase in nutrient levels, pH, temperature, and organic pollution. The inclusion of spatial and temporal variables in the
RDA model captured additional 24% of the diatom variance and revealed three more gradients, a spatial gradient represented
by higher order polynomial terms of latitude and longitude, and two temporal gradients of annual and seasonal variation. Partial
RDAs demonstrated that the unique contribution of each predictor set to the explained diatom variance was the highest in the
spatial dataset (16%), followed by the environmental (9%), and the temporal (7%) datasets. The remaining 28% of the variance
was explained by the covariance of the predictor sets. This suggests that in biomonitoring of single stream basins, the cheap
and simple account of space and time would explain most of the variance in assemblage composition obviating the necessity
of expensive and time-consuming environmental assessments. The nature of the underlying environmental mechanisms can be easily
inferred from the diatom composition itself. 相似文献
216.
Heavy Metal Concentrations in Water, Sediment, Fish and Some Benthic Organisms from Tigris River, Turkey 总被引:4,自引:0,他引:4
In this study concentrations of heavy metals, such as Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn were determined in water, sediment,
muscle, liver and gill of fish (Silurus triostegus, Mastacembelus simack, Mystus halepensis, Orthrias euphraticus) the muscle and liver of crab (Potamon fluviatilis), the internal organs of fresh water snail (Physa acuta), and mussel (Unio elongatulus), and in whole biomass of green algae (Spirogyra sp.) examples collected seasonally from three selected sites (I, II, and III) of Tigris River and from a reference site on
Resan Creek. In general, the average Cd, Cu, Mn, Ni, Zn, and Fe values in Sites I, II, and III were found to be high in spring
and summer. The concentrations of heavy metals in the Tigris River are compared with previous studies in the same sites. The
results showed that Cu levels have gradually decreased during recent years. In Tigris River, among the living organisms, i.e.,
those which are living in benthic region and showing biomonitor characteristic, crab, snail, green algae, mussel and fish
are seen to be formed in sequence. Cu, Fe, Mn and Zn values obtained from the muscle of fish and from the mass of internal
organs of mussel and snail were found to be under the acceptable values suggested. 相似文献
217.
Almeida CA Quintar S González P Mallea MA 《Environmental monitoring and assessment》2007,133(1-3):459-465
A study of the water quality of the Potrero de los Funes River (San Luis – Argentina) was carried out in order to evaluate
the possible effect of the anthropogenic activities on the river developed in the homonymous town. Samples were collected
during the period March 2000–November 2005 at three selected sampling sites (RP1, RP2 and RP3). Different physicochemical and bacteriological parameters (turbidity, pH, conductivity, suspended solids, alkalinity, potassium,
sodium, calcium, magnesium, chlorides, nitrates, phosphates, sulphates, chemical oxygen demand (COD), 5-day biological oxygen
demand (BOD5), dissolved oxygen, total coliforms, Escherichia coli and total heterotrophic bacteria) were analysed according to the Standard Method for the Examination of Water and Wastewater.
When comparing the values of total coliforms, E. coli, total heterotrophic bacteria, COD, BOD5 and phosphates from the zone without anthropogenic influence (RP1) and the urban zones (RP2 and RP3) an important variation in the parameters was observed. These results indicate that the urban activity produces a serious
and negative effect on the water quality, thus constituting a sanitary risk and may have a major impact on the trophic status
of the Potrero de los Funes dam. As case study, we report on the use of General Quality Index (GQI) to evaluate spatial and
seasonal changes in the water quality of Potrero de los Funes River. Results revealed a significant degradation of the water
quality at RP2 and RP3. 相似文献
218.
提出了以GM(1,1)模型拟合发展的趋势、傅里叶变换撮周期分量AR(p)模型模拟随机过程的集成预报模型,并用于黄河三角洲人工草场群落土壤盐分的定量研究中,经理论和应用检验证明:该模型能以较高的精度模拟或预报土壤盐分在较长时期内的动态变化过程,方法简单,计算工作量小,并优于传统的单一预报模型。 相似文献
219.
The planning and management of coastal sites in Catalonia has been mainly concerned with rendering beaches functional for
mass frequentation. This has caused serious problems for the beaches, including the alteration of dune formation processes
and the destruction of beach vegetation and habitats. Municipal capacity to plan and manage beaches is theoretically very
limited and relegated to the design of plans related to the maintenance of facilities for beach users. Nonetheless, a singular
experience, led by a local council in the metropolitan area of Barcelona demonstrates the crucial role that a local administration
can play in achieving a balance between habitat preservation and social use based on sustainable coastal management objectives,
in spite of a restrictive legislation. 相似文献
220.
William Ritchie 《Journal of Coastal Conservation》2000,6(2):207-218
The Sands of Forvie, National Nature Reserve, Scotland is a complex coastal sand dune system which is associated with the
dynamic estuary of the River Ythan. The dune system has developed over more than 5000 years. The south part is a peninsula
of dunes, sand hills, sand arcs, erosion and deflation surfaces. The north part is superimposed on a rock plateau with a cliff
coastline. This plateau is covered in glacial deposits and is essentially an upland heath landscape. Some of the best examples
of large active parabolic dunes in Britain are found in North Forvie. The sequence of geomorphic development is described.
As a nature reserve with a rich ecology it has been managed for conservational purposes since 1960s. As such it is an excellent
case study of how conservational management has changed to become more flexible and more aware of the importance of dynamic
processes. 相似文献