全文获取类型
收费全文 | 17280篇 |
免费 | 113篇 |
国内免费 | 189篇 |
专业分类
安全科学 | 417篇 |
废物处理 | 740篇 |
环保管理 | 1851篇 |
综合类 | 3677篇 |
基础理论 | 4421篇 |
环境理论 | 7篇 |
污染及防治 | 4140篇 |
评价与监测 | 1313篇 |
社会与环境 | 938篇 |
灾害及防治 | 78篇 |
出版年
2022年 | 136篇 |
2021年 | 121篇 |
2019年 | 105篇 |
2018年 | 308篇 |
2017年 | 321篇 |
2016年 | 494篇 |
2015年 | 284篇 |
2014年 | 429篇 |
2013年 | 1070篇 |
2012年 | 858篇 |
2011年 | 798篇 |
2010年 | 505篇 |
2009年 | 556篇 |
2008年 | 611篇 |
2007年 | 647篇 |
2006年 | 606篇 |
2005年 | 878篇 |
2004年 | 957篇 |
2003年 | 848篇 |
2002年 | 491篇 |
2001年 | 634篇 |
2000年 | 397篇 |
1999年 | 290篇 |
1998年 | 150篇 |
1997年 | 174篇 |
1996年 | 176篇 |
1995年 | 196篇 |
1994年 | 182篇 |
1993年 | 137篇 |
1992年 | 165篇 |
1991年 | 178篇 |
1990年 | 170篇 |
1989年 | 144篇 |
1988年 | 156篇 |
1987年 | 96篇 |
1986年 | 130篇 |
1985年 | 127篇 |
1984年 | 122篇 |
1983年 | 115篇 |
1982年 | 120篇 |
1981年 | 120篇 |
1980年 | 88篇 |
1979年 | 100篇 |
1978年 | 101篇 |
1976年 | 92篇 |
1974年 | 106篇 |
1972年 | 89篇 |
1967年 | 101篇 |
1966年 | 86篇 |
1964年 | 93篇 |
排序方式: 共有10000条查询结果,搜索用时 569 毫秒
821.
Flora of the still unchanged or slightly modified floodplains is particularly valuable. Such are the natural, periodically flooded riparian ecosystems within the Mid-Pripyat river valley in Belarus. Distinctive elements of that area are ‘periodic islands’, which arise from the most elevated parts of the riverbed during flooding and have a specific microtopography. The aim of the research was to recognize floristic composition and ecological conditions of the ‘islands.’ Noted plants were mainly photophilous, by clearly varied in soil moisture, acidity and fertility requirements. 相似文献
822.
This paper quantitatively assesses the influences of various demographic and socio-economic factors, past adaptive behavioral
factors, access to weather/climate information, and spatial/locational factors on coastal populations’ perceived adaptive
capacity against major impacts of hydro-meteorological disasters on their livelihood. A total of 285 respondents from three
coastal villages in Bangladesh were randomly interviewed between January and April 2009. Respondents rated their perceived
adaptive capacity against 25 anticipated impacts of sea-level rise (SLR)-induced events on their livelihood. By employing
the principal component analysis (PCA), perceived adaptive capacity was grouped into five major categories. Then, an adaptive
capacity index for each of five major impacts, namely, “infrastructure damage and disrupted mobility,” “food and nutritional
insecurity,” “low earning and higher cost of maintenance,” “loss of employment in offshore activities,” and “crisis of potable
water and public health risk,” was prepared. How adaptive capacity against each of these major five categories of impacts
differs due to the influence of various factors was assessed by employing the multivariate analysis of variance (MANOVA) technique.
The MANOVAs show that age, sex, level of education, type of occupation, farmland holdings, past adaptive behavior against
rainfall, salinity intrusion, freshwater crises, use of radio for weather information, and the distance of the homestead from
the shoreline have varying levels of influence on respondents’ perceived adaptive capacity against each of the five major
categories of impacts. Others factors have moderate to limited influences. The policy implication is that specific programs,
rather than a generic one-size fits all program, must be initiated for enhancement of adaptive capacity against specific impacts. 相似文献
823.
824.
Kishor Atreya Fred H?kon Johnsen Bishal Kumar Sitaula 《Environment, Development and Sustainability》2012,14(4):477-493
There is a growing concern of pesticide risks to human health, natural environment and ecosystems. Many previous economic valuations have accounted health aspects or environmental components, but rarely combined; thus, overall risk assessment is partially distorted. The study, conducted close to the capital of Nepal, addressed the health effects of pesticides on small-scale farmers and evaluated the monetary risks of pesticide use on human health and environmental resources. We also aim to establish the relationships among valuation methods. The paper adopts cost of illness, defensive expenditure and contingent valuation willingness to pay approach. The study concluded that the methods used for valuing pesticide risks to human and environmental health are theoretically consistent. The exposed individuals are likely to bear significant economic costs of exposures depending on geographical location, pesticide use magnitudes and frequency. Individuals are willing to pay between 53 and 79% more than the existing pesticide price to protect their health and environment. The integrated pest management training is less likely to reduce health costs of pesticide exposure, although it leads to higher investment in safety measures. 相似文献
825.
In industrialized countries, the idea of degrowth has emerged as a response to environmental, social, and economic crises.
Realizing environmental limits to and failures of more than half a century of continual economic growth in terms of social
progress and environmental sustainability, the degrowth paradigm calls for a downscaling of consumption and production for
social equity and ecological sustainability. The call for economic degrowth is generally considered to be delimited to rich
countries, where reduced consumption can save “ecological space” enabling people in poor countries to enjoy the benefits of
economic growth. China, as one of the economically most expanding countries in the world, has dramatically improved its living
standards, particularly along the Eastern coast, over the latest 30 years. However, China is absent from the international
debates on growth. This article discusses the implications of the Western degrowth debates for China. Given the distinctive
features of China’s development, the paper aims to enrich the degrowth debates, which have hitherto been dominated by Western
perspectives. Based upon reflections on social, environmental, and moral dimensions of economic growth, the paper argues that
limited natural resources may not continuously support universal affluence at the current level of the rich countries, a level
that China is likely to reach within a few decades. Priority for growth in China should therefore be given to the poor regions
of the country, and future growth should be beneficial to social and environmental development. 相似文献
826.
G. N. Tikhonova I. A. Tikhonov E. V. Kotenkova A. I. Munteanu I. G. Uspenskaya Yu. N. Konovalov V. I. Burlaku V. F. Kiku S. D. Georgitsa N. K. Karaman V. B. Nistreanu A. N. Mal’tsev 《Russian Journal of Ecology》2012,43(3):236-242
Comparative analysis of the structure of small mammal communities has been performed in two European cities located in different biomes: Chisinau (2008?C2009) and Yaroslavl (1994?C2002). The parameters studied included abundance, species composition, similarity and difference of faunas, species diversity, and proportions of groups differing in predisposition to synanthropy. It has been found that the structure of small mammal communities in these cities depends on specific physiographic conditions of the surrounding areas and on the distinctive features of the cities themselves (their structure, age, etc.). The similarity between the faunas is accounted for by the common ecological patterns of fauna formation in the biota of urban cenoses. 相似文献
827.
D. F. Adams R. K. Koppe 《Journal of the Air & Waste Management Association (1995)》2013,63(6):410-415
Light aircraft and helicopters have been occasionally used to conduct aerial traverses for a single pollutant or atmospheric tracer. The continuous analyzer or sample collector is temporarily tied down with a seat belt or hand held. Flight variables are visually observed and written on the recorder chart, a notebook or possibly voice-recorded on a portable tape recorder. The versatile airborne instrumentation package described can measure and record up to 27 pollutant and flight variables from a Cessna Skymaster center-line thrust, light twin. Real-time analysis instrumentation include non-dispersive infrared analyzers for CO2, CO, and hydrocarbons, conductivity and coulometric analyzers for sulfur dioxide and sulfur-containing gases, and Charlson-Ahlquist visual range nephelometer. A Battelle “bulk sampler” is used to collect particulates for weighing and microscopic examination. Indicated air speed, altitude, rate of climb, magnetic heading, temperature, and relative humidity are continuously measured. All variables are sequentially recorded on a 7-track, 200 bit per second, 27-channel, magnetic tape data logging system. Measured variables are recorded once each 0.3 to 0.8 sec—equivalent to 33-100 ft of traversedepending upon the number of variables recorded (i.e., between 9 and 27) when flying at 90 mph. Tape data are reduced directly by IBM 360 computer to a digital print-out or from tape to an X-Y analog plot. 相似文献
828.
Wm. E. Wilson Jr. D. F. Miller A. Levy R. K. Stone 《Journal of the Air & Waste Management Association (1995)》2013,63(11):949-956
Aerosols attributable to automobile exhaust can be classified as two types—primary aerosol (initially present in the exhaust) and secondary aerosol (generated photochemically from hydrocarbons and nitrogen oxides in the exhaust). In this study, investigation was made of possible effects of motor-fuel composition on the formation of these aerosols. Secondary aerosol, of principal interest in this work, was produced by irradiating auto exhaust in Battelle-Columbus’ 610 ft3 environmental chamber. A limited number of determinations of primary aerosol in diluted auto exhaust was made at the exit of a 36 ft dilution runnel. Determination of both primary and secondary aerosol was based on light-scattering measurements. Exhaust was generated with seven full-boiling motor gasolines, both leaded and nonleaded, in a 1967 Chevrolet which was not equipped with exhaust-emission control devices. Changes in fuel composition produced a maximum factor of three difference in light scattering due to primary aerosol. Aerosol yields, for consecutive driving cycles on the same fuel, vary considerably; as a result, ranking the fuels on the basis of average primary aerosol yield was not very meaningful. In addition to fuel composition, the more important independent variables are initial SO2 concentration, relative humidity and initial hydrocarbon concentration. Statistical analysis of the data indicates that the seven test fuels can be divided into two arbitrary groups with regard to secondary aerosol-forming potential. The fuels in the lower light-scattering group had aromatic contents of 15 and 21%, while those in the higher light-scattering group had aromatic contents of 25, 48, and 55%. Although the fuels can be grouped on the basis of a compositional factor, the grouping of fuels with aromatic content ranging from 25 to 55% indicates that this compositional factor cannot be equated simply with aromatic content. In an associated study of the aerosol-forming potential of individual hydrocarbons prominent in auto exhaust, it was observed that aromatics produce substantially more photochemical aerosol than olefins and paraffins. However, experiments with binar/hydrocarbon mixtures containing aromatjcs, as well as in these exhaust experiments, a strong dependence of aerosol yield on the aromatic components is is not observed. Thus, the data indicate that the dependence of secondary aerosol formation on fuel factors is a complex one and cannot be predicted solely on the basis of a sirigle hydrocarbon component reactivity scale. The two types of automobile aerosol did not have the same dependence on fuel, composition. The variation in total light scattering attributable to primary plus secondary aerosol was less than that due to either component alone. It therefore was concluded that the light scattering due to automobile exhaust emissions in these experiments was not significantly affected by changing fuel composition. 相似文献
829.
H.P. Schuchmann K.J. Laidler 《Journal of the Air & Waste Management Association (1995)》2013,63(1):52-53
Recent studies of organic pyrolyses in the presence of nitric oxide have shown that various nitogen compounds, such as hydrogen cyanide (HCN) and aceto-nitrile (CH3CN) are formed. This suggests the possibility that such compounds will be found in internal combustion processes, and may be present in automobile exhaust gases. The present paper describes some gas-chromatographic and wet analyses of exhaust gases. It is concluded that the amounts of hydrogen cyanide are less than 1 ppm, but that various organic nitrogen compounds may reach a level of about 100 ppm. The significance of these results is discussed. 相似文献
830.
Laurel J. Staley Marta K. Richards George L. Huffman Robert A. Olexsey Barry Dellinger 《Journal of the Air & Waste Management Association (1995)》2013,63(3):321-331
Measurements conducted on full-scale hazardous waste incinerators have occasionally shown a relationship between carbon monoxide (CO) emissions and emissions of toxic organic compounds. In this study, four mixtures of chlorinated C1 and C2 hydrocarbons were diluted in commercial-grade heptane and burned in a water-cooled turbulent flame reactor (TFR) under two different excess air levels. No correlation between CO and organic emissions could be discerned. Reasons for this lack of observable correlations are discussed in terms of combustion and chemical reaction kinetic theory. 相似文献