全文获取类型
收费全文 | 5572篇 |
免费 | 49篇 |
国内免费 | 27篇 |
专业分类
安全科学 | 155篇 |
废物处理 | 262篇 |
环保管理 | 436篇 |
综合类 | 899篇 |
基础理论 | 1371篇 |
环境理论 | 5篇 |
污染及防治 | 1780篇 |
评价与监测 | 424篇 |
社会与环境 | 297篇 |
灾害及防治 | 19篇 |
出版年
2023年 | 61篇 |
2022年 | 131篇 |
2021年 | 152篇 |
2020年 | 80篇 |
2019年 | 88篇 |
2018年 | 191篇 |
2017年 | 209篇 |
2016年 | 280篇 |
2015年 | 190篇 |
2014年 | 288篇 |
2013年 | 439篇 |
2012年 | 319篇 |
2011年 | 359篇 |
2010年 | 242篇 |
2009年 | 211篇 |
2008年 | 345篇 |
2007年 | 302篇 |
2006年 | 256篇 |
2005年 | 199篇 |
2004年 | 179篇 |
2003年 | 160篇 |
2002年 | 129篇 |
2001年 | 89篇 |
2000年 | 49篇 |
1999年 | 49篇 |
1998年 | 25篇 |
1997年 | 23篇 |
1996年 | 28篇 |
1995年 | 35篇 |
1994年 | 37篇 |
1993年 | 18篇 |
1992年 | 21篇 |
1991年 | 24篇 |
1990年 | 23篇 |
1989年 | 21篇 |
1988年 | 18篇 |
1987年 | 18篇 |
1986年 | 28篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 19篇 |
1982年 | 21篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1972年 | 9篇 |
1966年 | 16篇 |
1965年 | 10篇 |
1957年 | 9篇 |
1956年 | 11篇 |
1954年 | 9篇 |
排序方式: 共有5648条查询结果,搜索用时 406 毫秒
511.
Martín-Duque JF Pedraza J Sanz MA Bodoque JM Godfrey AE Díez A Carrasco RM 《Environmental management》2003,32(4):488-498
Landform-based physiographic maps, also called land systems inventories, have been widely and successfully used in undeveloped/rural areas in several locations, such as Australia, the western United States, Canada, and the British ex-colonies. This paper presents a case study of their application in a developed semi-urban/suburban area (Segovia, Spain) for land use planning purposes. The paper focuses in the information transfer process, showing how land use decision-makers, such as governments, planners, town managers, etc., can use the information developed from these maps to assist them. The paper also addresses several issues important to the development and use of this information, such as the goals of modern physiography, the types of landform-based mapping products, the problem of data management in developed areas, and the distinctions among data, interpretations, and decisions. 相似文献
512.
Perceval O Pinel-Alloul B Méthot G Couillard Y Giguère A Campbell PG Hare L 《Environmental pollution (Barking, Essex : 1987)》2002,118(1):5-17
The relative influence of limnological confounding factors on cadmium (Cd) bioaccumulation and metallothionein (MT) synthesis was quantified in natural populations of freshwater bivalves (Pyganodon grandis) living in lakes along a Cd concentration gradient. During the ice-free period, we measured 15 environmental variables in the water compartment and determined total concentrations of Cd and MT in the gills of bivalves at 37 littoral stations in 20 lakes distributed across the mining area of Rouyn-Noranda in northwestern Quebec. A multiple linear regression model including pH (+), dissolved Ca concentrations (-) and free Cd2+ concentrations at the sediment-water interface (+) explained 74% of the variability in Cd concentrations in the bivalve gills. Dissolved Ca (-) and free Cd2+ (+) together explained 62% of the variation in MT concentrations in the bivalve gills. Partial linear regression analyses indicated that the limnological factors' pure and shared effects together accounted for 48 and 45% of the total variation in Cd and MT concentrations in the gills, respectively. A lake selection procedure that could be applied in monitoring programs is proposed to minimise the relative influence of these confounding variables. 相似文献
513.
High resolution mass spectrometry gas chromatography (GC/MS) is the standard method for dioxin and furan analysis in environmental matrices. Considered as very accurate, this method is however time consuming and expensive. Methods based on biological interactions have the necessary sensitivity but began only recently to be investigated in the context of environmental applications. We have compared dioxin and furan toxicity levels (expressed as toxic equivalent quantities (TEQs)) in soil samples by three analytical approaches: the micro-ethoxyresorufin-o-deethylase (EROD) bioassay (a receptor-based method), an immunoassay (antibody-based method) and GC/MS analysis (used as a reference) using a shortened extraction-purification method. Both biological methods were sensitive to interferences from compounds co-extracted from samples. Most samples were underestimated by the immunoassay and, at a greater extent, overestimated by the EROD bioassay. The average accuracy of TEQ estimation (86 +/- 45% of values established by GC/MS) and the absence of false-negatives showed by the immunoassay suggest the usefulness of this method for semi-quantitative, preliminary characterization of potentially contaminated sites. 相似文献
514.
Subsurface drainage systems are useful tools to study chemical leaching in soils. Our objective was to compare the breakthrough behavior of bromide, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamid] to tile drains under two fall tillage practices (conventional tillage [CT] with a moldboard plow, and reduced tillage [RT] with a chisel plow) in field plots cultivated with corn (Zea mays L.). Leachate volume were greater in RT than in CT, with no statistical differences. Soil analysis showed that bromide migrated deeper in the soil profile than both herbicides, with little tillage effect. All chemicals were detected in drainage water at the same time and followed an event-driven behavior. Tillage had no effect on atrazine and metolachlor found in drainage water, while bromide concentration peaks were higher in RT than in CT in 1999. Concentration peaks were recorded earlier for atrazine and metolachlor than for bromide. Plots of cumulative relative chemical mass (cumulative mass divided by total mass measured in drainage) as a function of cumulative drainage were mostly linear for bromide, while they were S-shaped for both herbicides. Drainage that corresponded to 50% of relative cumulative mass ranged from 40 to 55% for bromide and from 5 to 28% for both herbicides. Rapid chemical movement to tile drains suggested that preferential flow was important in both CT and RT, and that these tillage practices had little influence on this phenomena. 相似文献
515.
Effects of cadmium on sediment processing on members of the Capitella species-complex 总被引:2,自引:0,他引:2
The effect of cadmium on sediment processing by laboratory-cultured specimens of Capitella sp I and Capitella sp B was investigated. Specimens were exposed to 0, 60, 90 and 140 microg Cd g(-1) dry weight sediment for a 10 day period (two census days) to observe effects of cadmium on their feeding activity. Under unstressed conditions, Capitella sp I specimens were larger, had higher biomass and produced more fecal pellets than Capitella sp B. Cadmium concentrations had no effect on pellet production and body mass of the studied populations. However, cadmium exposure time significantly affected Capitella sp B pellet production and body mass of both populations following different trends: after 10 days of exposure, the average processed sediment per unit worm mass decreased in Capitella sp I but increased in Capitella sp B. The latter population did not reduce its feeding activity in the presence of cadmium maybe related to the fact that it is derived from a highly polluted environment. This study has shown an unimpaired response of Capitella sp I and Capitella sp B to cadmium in their sediment processing activity, which indicates the potential importance of this species complex in the trophic transfer of metals from sediments to other marine organisms. 相似文献
516.
Hazenkamp-von Arx ME Götschi Fellmann T Oglesby L Ackermann-Liebrich U Gíslason T Heinrich J Jarvis D Luczynska C Manzanera AJ Modig L Norbäck D Pfeifer A Poll A Ponzio M Soon A Vermeire P Künzli N 《Journal of the Air & Waste Management Association (1995)》2003,53(5):617-628
The follow-up of a cohort of adults from 29 European centers of the former European Community Respiratory Health Survey (ECRHS) I (1989-1992) will examine the long-term effects of exposure to ambient air pollution on the incidence, course, and prognosis of respiratory diseases, in particular asthma and decline in lung function. The purpose of this article is to describe the methodology and the European-wide quality control program for the collection of particles with 50% cut-off size of 2.5 microm aerodynamic diameter (PM2.5) in the ECRHS II and to present the PM2.5 results from the winter period 2000-2001. Because PM2.5 is not routinely monitored in Europe, we measured PM2.5 mass concentrations in 21 participating centers to estimate background exposure in these cities. A standardized protocol was developed using identical equipment in each center (U.S. Environmental Protection Agency Well Impactor Ninety-Six [WINS] and PQ167 from BGI, Inc.). Filters were weighed in a single central laboratory. Sampling was conducted for 7 days per month for a year. Winter mean PM2.5 mass concentrations (November 2000-February 2001) varied substantially, with Iceland reporting the lowest value (5 microg/m3) and northern Italy the highest (69 microg/m3). A standardized procedure appropriate for PM2.5 exposure assessment in a multicenter study was developed. We expect ECRHS II to have sufficient variation in exposure to assess long-term effects of air pollution in this cohort. Any bias caused by variation in the characteristics of the chosen monitoring location (e.g., proximity to traffic sources) will be addressed in later analyses. Given the homogenous spatial distribution of PM2.5, however, concentrations measured near traffic are not expected to differ substantially from those measured at urban background sites. 相似文献
517.
Lefèvre G Bessière J Ehrhardt JJ Walcarius A 《Journal of environmental radioactivity》2003,70(1-2):73-83
In the goal of finding efficient scavengers for radioiodide in conditions (pH, pE) close to those encountered in deep geological sites, sorption of iodide ions on cuprous sulfide minerals (especially roxbyite, Cu(1.75)S) has been studied. Surface analysis by X-ray photoelectron spectroscopy has shown that commercial cuprous sulfides are covered by an oxidized overlayer (mainly in the form of CuSO(4)). Therefore, a synthetic procedure to get roxbyite (typically by mixing Na(2)S with an aqueous suspension of commercial Cu(2)O) was applied to produce pure samples with clean surfaces. Batch equilibration of cuprous sulfide particles suspended in aqueous solutions containing iodide species has revealed significant consumption of iodide. The sorption mechanism involves the formation of a surface complex via the exchange of surface hydroxyl groups by iodide anions, as highlighted by a transient pH increase during the immobilization process. Other copper and mixed copper-iron sulfides (e.g. CuS, CuFeS(2)), which are stable over wide pH and potential ranges are also likely to accumulate iodide species. Because of the specific interaction between iodide and copper(I) centers on the minerals, high distribution coefficients (>1000 ml/g) were observed. 相似文献
518.
Denys S Echevarria G Florentin L Leclerc-Cessac E Morel JL 《Journal of environmental radioactivity》2003,70(1-2):115-126
Models for safety assessment of radioactive waste repositories need accurate values of the soil-to-plant transfer of radionuclides. In oxidizing environments, (99)Tc is expected to occur as pertechnetate ((99)TcO(4)(-)). Due to its high mobility, leaching of this element in the field might be important, potentially affecting the reliability of estimated transfer parameters of (99)Tc as measured in closed experimental systems such as hydroponics or pot experiments. The aim of this experiment was to measure the leaching of (99)Tc in undisturbed irrigated soil cores under cultivation as well as plant uptake and to study the possible competition between the two transfer pathways. Undisturbed soil cores (50 x 50 cm) were sampled from a Rendzic Leptosol (R), a colluvial Fluvic Cambisol (F) and a Dystric Cambisol (D) using PVC tubes (three cores sampled per soil type). Each core was equipped with a leachate collector at the bottom, allowing the monitoring of (99)Tc leaching through the cores. Cores were placed in a greenhouse and maize (Zea mays L., cv. DEA, Pioneer) was sown. After 135 d, maize was harvested and radioactivity determined in both plant and water samples. Results showed that during the growing period, leaching of (99)Tc was limited, due to the high evapotranspiration rate of maize. After harvest, leaching of (99)Tc went on because of the absence of evapotranspiration. Effective uptake (EU) of (99)Tc in leaves and grains was calculated. EU reached 70% of the input in the leaves and was not significantly different among soils. These results confirmed those obtained from pot experiments, even though leaching was allowed to occur in close-to-reality hydraulical conditions. As a consequence, it was concluded that pot experiments are an adequate surrogate for more complex "close-to-reality" experimental systems for measuring transfer factors. 相似文献
519.
Veiga LH Koifman S Melo VP Sachet I Amaral EC 《Journal of environmental radioactivity》2003,70(3):161-176
This paper aims to present an assessment of the environmental radiological exposure at a Brazilian area of high natural radiation and discusses the indoor radon exposure risk. A survey of inhabitant exposures arising from the inhalation of radon progeny and external gamma exposure was conducted in urban and rural areas of the Po?os de Caldas Plateau, which is recognized worldwide as a high natural radiation region. The results of this survey indicated that highest radiation exposure was restricted to the rural area of Po?os de Caldas. The radiation exposure in urban locations was quite similar to the values observed in normal background areas in some Brazilian counties. By the application of a constant relative risk model, an additional 20% in the lifetime risk of lung cancer mortality due to the exposure to radon progeny was estimated at Po?os de Caldas. It was also estimated that 16% of all lung cancer deaths at Po?os de Caldas county could be attributable to radon exposure. 相似文献
520.
2 semiarid irrigated area with salt-affected soils. The available soil map is at 1:100,000 scale and its mapping units are
used for the land evaluation with the FAO framework. These data are then elaborated using the index value method. This procedure
gives a map of land evaluation units and a table that rates the productive potential of these units for six crops: alfalfa,
barley, maize, rice, sunflower, and wheat. 相似文献