全文获取类型
收费全文 | 2240篇 |
免费 | 17篇 |
国内免费 | 91篇 |
专业分类
安全科学 | 105篇 |
废物处理 | 210篇 |
环保管理 | 280篇 |
综合类 | 295篇 |
基础理论 | 392篇 |
环境理论 | 1篇 |
污染及防治 | 783篇 |
评价与监测 | 193篇 |
社会与环境 | 74篇 |
灾害及防治 | 15篇 |
出版年
2023年 | 11篇 |
2022年 | 34篇 |
2021年 | 36篇 |
2020年 | 12篇 |
2019年 | 41篇 |
2018年 | 70篇 |
2017年 | 58篇 |
2016年 | 78篇 |
2015年 | 54篇 |
2014年 | 67篇 |
2013年 | 178篇 |
2012年 | 123篇 |
2011年 | 143篇 |
2010年 | 96篇 |
2009年 | 129篇 |
2008年 | 134篇 |
2007年 | 144篇 |
2006年 | 129篇 |
2005年 | 114篇 |
2004年 | 105篇 |
2003年 | 97篇 |
2002年 | 88篇 |
2001年 | 62篇 |
2000年 | 35篇 |
1999年 | 24篇 |
1998年 | 20篇 |
1997年 | 23篇 |
1996年 | 16篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 19篇 |
1992年 | 10篇 |
1991年 | 19篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1978年 | 6篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1971年 | 6篇 |
1969年 | 5篇 |
排序方式: 共有2348条查询结果,搜索用时 687 毫秒
761.
Clark SG Rutherford MB Auer MR Cherney DN Wallace RL Mattson DJ Clark DA Foote L Krogman N Wilshusen P Steelman T 《Environmental management》2011,47(5):716-726
Environmental studies and environmental sciences programs in American and Canadian colleges and universities seek to ameliorate environmental problems through empirical enquiry and analytic judgment. In a companion article (Part 1) we describe the environmental program movement (EPM) and discuss factors that have hindered its performance. Here, we complete our analysis by proposing strategies for improvement. We recommend that environmental programs re-organize around three principles. First, adopt as an overriding goal the concept of human dignity??defined as freedom and social justice in healthy, sustainable environments. This clear higher-order goal captures the human and environmental aspirations of the EPM and would provide a more coherent direction for the efforts of diverse participants. Second, employ an explicit, genuinely interdisciplinary analytical framework that facilitates the use of multiple methods to investigate and address environmental and social problems in context. Third, develop educational programs and applied experiences that provide students with the technical knowledge, powers of observation, critical thinking skills and management acumen required for them to become effective professionals and leaders. Organizing around these three principles would build unity in the EPM while at the same time capitalizing on the strengths of the many disciplines and diverse local conditions involved. 相似文献
762.
Federal land management agencies, such as the USDA Forest Service, have expanded the role of recreation partners reflecting
constrained growth in appropriations and broader societal trends towards civic environmental governance. Partnerships with
individual volunteers, service groups, commercial outfitters, and other government agencies provide the USDA Forest Service
with the resources necessary to complete projects and meet goals under fiscal constraints. Existing partnership typologies
typically focus on collaborative or strategic alliances and highlight organizational dimensions (e.g., structure and process)
defined by researchers. This paper presents a partner typology constructed from USDA Forest Service partnership practitioners’
conceptualizations of 35 common partner types. Multidimensional scaling of data from unconstrained pile sorts identified 3
distinct cultural dimensions of recreation partners—specifically, partnership character, partner impact, and partner motivations—that
represent institutional, individual, and socio-cultural cognitive domains. A hierarchical agglomerative cluster analysis provides
further insight into the various domains of agency personnel’s conceptualizations. While three dimensions with high reliability
(RSQ = 0.83) and corresponding hierarchical clusters illustrate commonality between agency personnel’s partnership suppositions,
this study also reveals variance in personnel’s familiarity and affinity for specific partnership types. This real-world perspective
on partner types highlights that agency practitioners not only make strategic choices when selecting and cultivating partnerships
to accomplish critical task, but also elect to work with partners for the primary purpose of providing public service and
fostering land stewardship. 相似文献
763.
764.
765.
Myong Hwan Sohn Kyung Won Seo Yong Seok Choi Sang Joon Lee Young Sil Kang Yang Soon Kang 《Marine Biology》2011,158(3):561-570
The marine dinoflagellate Cochlodinium polykrikoides is a harmful and highly motile algal species. To distinguish between the motility characteristics of solitary and chain-forming
cells, the swimming trajectories and speeds of solitary cells and 2- to 8-cell chains of C. polykrikoides were measured using a digital holographic particle tracking velocimetry (PTV) technique. C. polykrikoides cells exhibited helical swimming trajectories similar to other dinoflagellate species. The swimming speed increased as the
number of cells in the chain increased, from an average of 391 μm s−1 (solitary cells) to 856 μm s−1 (8-cell chain). The helix radius R and pitch P also increased as the number of cells in the chain increased. R increased from 9.24 μm (solitary cell) to 20.3 μm (8-cell chain) and P increased from 107 μm (solitary cell) to 164 μm (8-cell chain). The free thrust-generating motion of the transverse flagella
and large drag reduction in the chain-forming cells seemed to increase the swimming speed compared to solitary cells. The
measured swimming speeds agreed with those from field observations. The superior motility of chain-forming C. polykrikoides cells may be an important factor for its bloom, in addition to the factors reported previously. 相似文献
766.
Seo YN Lee MY 《Journal of environmental biology / Academy of Environmental Biology, India》2011,32(1):7-10
Benz[a]anthracene is a ubiquitous environmental contaminant formed during the incomplete combustion of organic material. Some of the metabolites of benz[a]anthracene are known to be toxic and carcinogenic. In this investigation, benz[a]anthracene-induced oxidative damage to lymphocyte DNA was evaluated with the Comet assay (single cell gel electrophoresis). The level of oxidative DNA damage caused by benz[a]anthracene increased in a dose-dependent manner (24, 49) and oxidative DNA damage was significantly inhibited by 5 and 10 microg ml(-1) ascorbate, 5 microg ml(-1) polyphenols, as well as 5 and 10 microg ml(-1) curcumin. Moreover, traditional Korean medicinal herbs such as Acanthopanax and ginseng significantly reduced DNA damage. The results demonstrate that antioxidant supplementation to lymphocytes inhibits oxidative DNA damage in vitro, supporting an inhibitory effect against oxidative DNA damage, probably due to reduction of reactive oxygen species production induced by benz[a]anthracene. 相似文献
767.
Yong Sik Ok Sang Soo Lee Weon-Tai Jeon Sang-Eun Oh Adel R. A. Usman Deok Hyun Moon 《Environmental geochemistry and health》2011,33(1):31-39
Liming materials have been used to immobilize heavy metals in contaminated soils. However, no studies have evaluated the use of eggshell waste as a source of calcium carbonate (CaCO3) to immobilize both cadmium (Cd) and lead (Pb) in soils. This study was conducted to evaluate the effectiveness of eggshell waste on the immobilization of Cd and Pb and to determine the metal availability following various single extraction techniques. Incubation experiments were conducted by mixing 0–5% powdered eggshell waste and curing the soil (1,246 mg Pb kg?1 soil and 17 mg Cd kg?1 soil) for 30 days. Five extractants, 0.01 M calcium chloride (CaCl2), 1 M CaCl2, 0.1 M hydrochloric acid (HCl), 0.43 M acetic acid (CH3COOH), and 0.05 M ethylendiaminetetraacetic acid (EDTA), were used to determine the extractability of Cd and Pb following treatments with CaCO3 and eggshell waste. Generally, the extractability of Cd and Pb in the soils decreased in response to treatments with CaCO3 and eggshell waste, regardless of extractant. Using CaCl2 extraction, the lowest Cd concentration was achieved upon both CaCO3 and eggshell waste treatments, while the lowest Pb concentration was observed using HCl extraction. The highest amount of immobilized Cd and Pb was extracted by CH3COOH or EDTA in soils treated with CaCO3 and eggshell waste, indicating that remobilization of Cd and Pb may occur under acidic conditions. Based on the findings obtained, eggshell waste can be used as an alternative to CaCO3 for the immobilization of heavy metals in soils. 相似文献
768.
Lee LA Lee EG Lee T Kim SW Slaven JE Harper M 《Journal of environmental monitoring : JEM》2011,13(3):527-535
Recent laboratory research indicates physiologic sampling of gas and vapor may provide more representative estimates of personal exposures than traditional methods. Modifications to the physiologic sampling pump (PSP) used in that research are described which extend its usefulness to size-selective sampling of particulates. PSPs used in previous research varied motor speed to keep sampling proportional to the subject's inhalation. This caused airflow and particle velocities through the collection device to continually change making those pumps unsuitable for sampling particulates. The modified implementation of the PSP pulls a constant airflow into and through a cyclone, then uses valves to either direct the airflow through, or divert the airflow around, the sampling filter. By using physiologic inputs to regulate the fraction of each second that air flows through the sampling filter, samples may be collected in proportion to inhalation rate. To evaluate the performance of a functional prototype 5 different sizes of monodisperse aerosols of ammonium fluorescein were generated by a vibrating orifice aerosol generator and introduced into a calm air chamber. To simulate different inhalation rates the valves of the PSP were energized using 9 different duty cycles. Efficiency curves are presented and compared to a standard respirable convention by bias mapping. The performance of the modified cyclone used in the PSP sampling head compared favorably with a commercially available cyclone of the same model, operating at a constant airflow (± 10% over almost all the size distributions of concern). The new method makes physiologic sampling of the respirable fraction of particulates feasible. 相似文献
769.
Haibo Niu Zhengkai Li Kenneth Lee Paul Kepkay Joseph V. Mullin 《Environmental Modeling and Assessment》2011,16(1):61-75
Spilled oil can interact with suspended particles in marine environments and form oil–mineral aggregates (OMAs). Some OMAs
with densities higher than seawater density can settle to the seedbed to pose potential risks to benthic organisms. To understand
the transport and fate of oil associated with OMAs and evaluate their potential risks, an integrated hydrodynamic and fate/transport
model has been used in a hypothetical case study of 1,000 tonnes of South Louisiana oil spilled in the Bristol Channel. Several
scenarios have been simulated under different wave and current conditions. By using OMA properties derived from laboratory
measurements reported in literature, it has been found that the risk to the benthos is unlikely for the two hypothetical cases
with strong currents, but it is likely for the wave only (weak current) case. The effects of other factors such as OMA properties
and sediment concentration were also examined in terms of their effects on the transport process and risks. 相似文献
770.
Jeong U Kim J Lee H Jung J Kim YJ Song CH Koo JH 《Journal of environmental monitoring : JEM》2011,13(7):1905-1918
The contributions of long range transported aerosol in East Asia to carbonaceous aerosol and particulate matter (PM) concentrations in Seoul, Korea were estimated with potential source contribution function (PSCF) calculations. Carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)), PM(2.5), and PM(10) concentrations were measured from April 2007 to March 2008 in Seoul, Korea. The PSCF and concentration weighted trajectory (CWT) receptor models were used to identify the spatial source distributions of OC, EC, PM(2.5), and coarse particles. Heavily industrialized areas in Northeast China such as Harbin and Changchun and East China including the Pearl River Delta region, the Yangtze River Delta region, and the Beijing-Tianjin region were identified as high OC, EC and PM(2.5) source areas. The conditional PSCF analysis was introduced so as to distinguish the influence of aerosol transported from heavily polluted source areas on a receptor site from that transported from relatively clean areas. The source contributions estimated using the conditional PSCF analysis account for not only the aerosol concentrations of long range transported aerosols but also the number of transport days effective on the measurement site. Based on the proposed algorithm, the condition of airmass pathways was classified into two types: one condition where airmass passed over the source region (PS) and another condition where airmass did not pass over the source region (NPS). For most of the seasons during the measurement period, 249.5-366.2% higher OC, EC, PM(2.5), and coarse particle concentrations were observed at the measurement site under PS conditions than under NPS conditions. Seasonal variations in the concentrations of OC, EC, PM(2.5), and coarse particles under PS, NPS, and background aerosol conditions were quantified. The contributions of long range transported aerosols on the OC, EC, PM(2.5), and coarse particle concentrations during several Asian dust events were also estimated. We also investigated the performance of the PSCF results obtained from combining highly time resolved measurement data and backward trajectory calculations via comparison with those from data in low resolutions. Reduced tailing effects and the larger coverage over the area of interest were observed in the PSCF results obtained from using the highly time resolved data and trajectories. 相似文献