全文获取类型
收费全文 | 29466篇 |
免费 | 324篇 |
国内免费 | 222篇 |
专业分类
安全科学 | 831篇 |
废物处理 | 1060篇 |
环保管理 | 4031篇 |
综合类 | 4660篇 |
基础理论 | 8531篇 |
环境理论 | 21篇 |
污染及防治 | 7707篇 |
评价与监测 | 1741篇 |
社会与环境 | 1239篇 |
灾害及防治 | 191篇 |
出版年
2022年 | 179篇 |
2021年 | 179篇 |
2019年 | 214篇 |
2018年 | 387篇 |
2017年 | 379篇 |
2016年 | 554篇 |
2015年 | 489篇 |
2014年 | 677篇 |
2013年 | 2132篇 |
2012年 | 841篇 |
2011年 | 1249篇 |
2010年 | 1025篇 |
2009年 | 1032篇 |
2008年 | 1249篇 |
2007年 | 1329篇 |
2006年 | 1182篇 |
2005年 | 1004篇 |
2004年 | 1003篇 |
2003年 | 937篇 |
2002年 | 936篇 |
2001年 | 1239篇 |
2000年 | 860篇 |
1999年 | 548篇 |
1998年 | 426篇 |
1997年 | 435篇 |
1996年 | 442篇 |
1995年 | 482篇 |
1994年 | 438篇 |
1993年 | 395篇 |
1992年 | 414篇 |
1991年 | 373篇 |
1990年 | 376篇 |
1989年 | 411篇 |
1988年 | 347篇 |
1987年 | 300篇 |
1986年 | 276篇 |
1985年 | 305篇 |
1984年 | 286篇 |
1983年 | 321篇 |
1982年 | 322篇 |
1981年 | 271篇 |
1980年 | 243篇 |
1979年 | 269篇 |
1978年 | 229篇 |
1977年 | 195篇 |
1976年 | 200篇 |
1975年 | 192篇 |
1974年 | 172篇 |
1973年 | 171篇 |
1972年 | 198篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
David Brandes Gregory J. Cavallo Michael L. Nilson 《Journal of the American Water Resources Association》2005,41(6):1377-1391
Rapid land development is raising concern regarding the ability of urbanizing watersheds to sustain adequate base flow during periods of drought. Long term streamflow records from unregulated watersheds of the lower to middle Delaware River basin are examined to evaluate the impact of urbanization and imperviousness on base flow. Trends in annual base flow volumes, seven‐day low flows, and runoff ratios are determined for six urbanizing watersheds and four reference watersheds across three distinct physiographic regions. Hydrograph separation is used to determine annual base flow and stormflow volumes, and nonparametric trend tests are conducted on the resulting time series. Of the watersheds examined, the expected effects of declining base flow volumes and seven‐day low flows and increasing stormflows are seen in only one watershed that is approximately 20 percent impervious and has been subject to a net water export over the past 15 years. Both interbasin transfers and hydrologic mechanisms are invoked to explain these results. The results show that increases in impervious area may not result in measurable reductions in base flow at the watershed scale. 相似文献
142.
H. J. Cranfield 《Marine Biology》1973,22(3):211-223
The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour. 相似文献
143.
Ryden JC Whitehead DC Lockyer DR Thompson RB Skinner JH Garwood EA 《Environmental pollution (Barking, Essex : 1987)》1987,48(3):173-184
Emissions of ammonia were measured from livestock excreta and fertilisers applied to grass swards, from grazed paddocks, from decomposing grass herbage and from an animal house containing dairy cows. Emissions from urine, dung, slurry and fertilisers were determined using a system of wind tunnels with each tunnel covering an area of 1 m(2). Emissions from grazed swards were determined using a micrometeorological mass balance method. From the results of these measurements, together with other published information, an inventory for ammonia emissions has been calculated for grassland and livestock production systems over the UK as a whole. It is estimated that emissions from grassland and cattle and sheep production amount to about 230 kt NH(3)-N annually, while emissions from pig and poultry production amount to about 40 kt and 80 kt NH(3)-N, respectively. 相似文献
144.
Jones GL Willy D Lumsden B Taufa T Lourie J 《Environmental pollution (Barking, Essex : 1987)》1987,48(2):101-115
It has long been known that mining activity can markedly change the level and distribution of certain heavy metals in the adjacent environment. This pollution can be quite widespread and long lasting and often has deleterious effects on the health of local populations. In the present study scalp hair was used as the biopsy material because of its ease of collection and long history of use in this connection. Hair was collected from all the local villages in the vicinity of the mine site, as well as from Papua New Guinean nationals from other provinces, and European expatriates who were employed by the mining company and who were resident in the area. Hair from local people showed a remarkably high iron content by comparison with previously studied populations. The extreme variations in hair iron levels were reflected in the differential distribution of levels according to location, age and sex. Hair cadmium was also high in the population studied. Hair copper, lead, zinc and mercury all appeared to be within 'normal' limits by comparison with other general populations. These results are discussed in the context of the environmental and social impact of the mining operations on the local people. 相似文献
145.
Knutson AB Klerks PL Levinton JS 《Environmental pollution (Barking, Essex : 1987)》1987,45(4):291-304
The distribution of heavy metal contaminated sediments in Foundry Cove, a freshwater embayment of the Hudson River, was examined twelve years after the discharging of wastes from a battery factory had ceased. Concentrations of Cd, Ni and Co were measured in surficial sediments (top 5 cm) and seven detailed depth profiles. Comparison with earlier surveys showed that metal levels of surficial sediments have been considerably reduced throughout the cove. Evidence suggests that this reduction may be largely due to burial rather than transport of metals out of the cove or a redistribution (via sediment resuspension and redeposition) within the cove. This is suggested by the presence of a peak in metal concentrations at a depth of several centimetres in depositional environments, a calculation showing the loss of waterborne cadmium to be much less than the amount of cadmium lost from the surficial sediment, and the absence of increased pollution in the cleaner parts of the cove. Despite improvement, metal levels remain extremely high, including a persistent 'hot-spot' with levels higher than 10 000 ppm Cd. 相似文献
146.
Marhuenda-Egea FC Martínez-Sabater E Jordá J Moral R Bustamante MA Paredes C Pérez-Murcia MD 《Chemosphere》2007,68(2):301-309
The aim of the present paper is to assess the maturity degree reached by different samples of several mixtures from winery and distillery residues composted using the Rutgers composting system, by means of excitation-emission matrix (EEM) fluorescence spectroscopy. The composts were sampled once a week for about 200d. EEM spectra indicate the presence of different fluorophores. The fluorescence intensities of these peaks show trends related to the maturity of the composting samples selected. The "contour density" of EEM maps is strongly modified through time. We have used the quantitative method of fluorescence regional integration (FRI). The EEMs were delineated into five excitation-emission regions. The degree of compost maturity could be correlated with the percentage of the volumetric integration under the EEM within each region. Further refinement of these techniques should provide a relatively rapid method for assessing the suitability of the compost to soil application. 相似文献
147.
The sensitivity of surface waters of Great Britain to acidification predicted from catchment characteristics 总被引:7,自引:0,他引:7
Hornung M Bull KR Cresser M Ullyett J Hall JR Langan S Loveland PJ Wilson MJ 《Environmental pollution (Barking, Essex : 1987)》1995,87(2):207-214
Using a combination of soil, land use and geological information, a map of Great Britain has been derived which indicates the sensitivity of surface waters to acidification. For the geological information, a slightly modified version of an available map was used which indicated the sensitivity of groundwaters to acidification. For soils, 1-km databases of soil information for England and Wales and for Scotland were employed to map the soil sensitivity as determined by buffering capacity. The derived soils map was modified to take account of agricultural liming in arable and managed grassland areas using the ITE Land Classification. The final map of surface water sensitivity was obtained by using a geographic information system overlay procedure which enabled each combination of soil and geology sensitivity to be uniquely defined. The final sensitivity classification was based upon expert knowledge and the experience of a similar sensitivity mapping exercise for Wales. 相似文献
148.
149.
Bacteria transport and deposition under unsaturated conditions: the role of the matrix grain size and the bacteria surface protein 总被引:1,自引:0,他引:1
Gargiulo G Bradford S Simůnek J Ustohal P Vereecken H Klumpp E 《Journal of contaminant hydrology》2007,92(3-4):255-273
Unsaturated (80% water saturated) packed column experiments were conducted to investigate the influence of grain size distribution and bacteria surface macromolecules on bacteria (Rhodococcus rhodochrous) transport and deposition mechanisms. Three sizes of silica sands were used in these transport experiments, and their median grain sizes were 607, 567, and 330 microm. The amount of retained bacteria increased with decreasing sand size, and most of the deposited bacteria were found adjacent to the column inlet. The deposition profiles were not consistent with predictions based on classical filtration theory. The experimental data could be accurately characterized using a mathematical model that accounted for first-order attachment, detachment, and time and depth-dependent straining processes. Visual observations of the bacteria deposition as well as mathematical modelling indicated that straining was the dominant mechanism of deposition in these sands (78-99.6% of the deposited bacteria), which may have been enhanced due to the tendency of this bacterium to form aggregates. An additional unsaturated experiment was conducted to better deduce the role of bacteria surface macromolecules on attachment and straining processes. In this case, the bacteria surface was treated using a proteolitic enzyme. This technique was assessed by examining the Fourier-transform infrared spectrum and hydrophobicity of untreated and enzyme treated cells. Both of these analytical procedures demonstrated that this enzymatic treatment removed the surface proteins and/or associated macromolecules. Transport and modelling studies conducted with the enzyme treated bacteria, revealed a decrease in attachment, but that straining was not significantly affected by this treatment. 相似文献
150.
Xian T. Lu Yun Ma Cui Wang Xiao F. Zhang Da Q. Jin Chang J. Huang 《Journal of environmental science and health. Part. B》2013,48(5):445-454
Previous studies have demonstrated that pesticides could induce cytotoxicity and genotoxicity in vivo and in vitro, and that oxidative stress may be an important factor involved. However, investigations comparing the capability of different organophosphorous (OP) compounds to induce cytotoxicity, genotoxicity and oxidative stress are limited. Hence, the aim of this paper was to access the cytotoxic and genotoxic effects of five OPs or metabolites, Acephate (ACE), Methamidophos (MET), Chloramidophos (CHL), Malathion (MAT) and Malaoxon (MAO), and to clarify the role of oxidative stress, using PC12 cells. The results demonstrated that MET, MAT and MAO caused significant inhibition of cell viability and increased DNA damage in PC12 cells at 40 mg L?1. MAO was more toxic than the other OPs. ACE, MET, MAT and MAO increased the levels of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA), and decreased the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) at 20 mg L?1 and 40 mg L?1 to different degrees. Pre-treatment with vitamin E(600 μM)caused a significant attenuation in the cytotoxic and genotoxic effect; pre-treatment reversed subsequent OP-induced elevation of peroxidation products and the decline of anti-oxidant enzyme activities. These results indicate that oxidative damage is likely to be an initiating event that contributes to the OP-induced cytotoxicity. 相似文献