全文获取类型
收费全文 | 64篇 |
免费 | 2篇 |
专业分类
安全科学 | 1篇 |
废物处理 | 3篇 |
环保管理 | 12篇 |
综合类 | 4篇 |
基础理论 | 25篇 |
污染及防治 | 18篇 |
评价与监测 | 1篇 |
社会与环境 | 1篇 |
灾害及防治 | 1篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2015年 | 4篇 |
2013年 | 6篇 |
2012年 | 1篇 |
2011年 | 6篇 |
2010年 | 11篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有66条查询结果,搜索用时 46 毫秒
31.
Effects of Long-Term Ungulate Exclusion and Recent Alien Species Control on the Preservation and Restoration of a Hawaiian Tropical Dry Forest 总被引:3,自引:0,他引:3
Robert J. Cabin Stephen G. Weller † David H. Lorence ‡ Tim W. Flynn ‡ Ann K. Sakai † Darren Sandquist § and Lisa J. Hadway‡ 《Conservation biology》2000,14(2):439-453
Abstract: Although the destruction of tropical rain forests receives much attention, tropical dry forests are in general far more threatened and endangered. Eliminating grazing ungulates is often considered a key first step toward protecting these ecosystems, but few studies have investigated the long-term effects of this technique. We examined the effects of ungulate exclusion from a 2.3-ha native dry-forest preserve on the island of Hawaii by comparing its present flora to the flora of an adjacent area subjected to continuous grazing since the preserve was fenced over 40 years ago. Relative to this adjacent area, the fenced preserve contained a more diverse flora with substantially greater coverage of native overstory and understory species. Until recently, however, regeneration of native canopy trees within the preserve appears to have been thwarted by a dominant herbaceous cover of alien fountain grass ( Pennisetum setaceum ) and predation by alien rodent species. Our results indicate that although ungulate exclusion may be a necessary and critical first step, it is not sufficient to adequately preserve and maintain Hawaii's remaining tropical dry forest remnants. Our recent efforts to control the dominant alien species within the fenced preserve suggest that this practice may facilitate both the regeneration of native species and the colonization and potential invasion of new alien plants. Comparisons of seedlings of the dominant native canopy tree Diospyros sandwicensis growing in sites both dominated by and free of fountain grass suggested that fountain grass inhibits Diospyros seedling growth and photosynthesis but may increase survival if seedlings are protected from ungulates. 相似文献
32.
Kevin J. Flynn 《Chemistry and Ecology》1990,4(3):109-116
Despite the fact that coccolithophorids such as Emiliania huxleyi are suspected to play an important role in carbon-cycling, there are few data from which to deduce how these organisms may respond to CO2-induced global warming. the nitrogen and phosphorus nutrient physiology of these organisms, together with its interaction with photosynthesis, needs to be studied especially in connection with the selection for coccolith forming individuals and the quantity and quality of the CaCO3 deposited in the coccoliths. Without such data, it will not be possible to model the contributions that these microalgae may play in arresting the increase in levels of atmospheric CO2. 相似文献
33.
Model‐Based Nitrogen and Phosphorus (Nutrient) Criteria for Large Temperate Rivers: 1. Model Development and Application 下载免费PDF全文
Kyle F. Flynn Michael W. Suplee Steven C. Chapra Hua Tao 《Journal of the American Water Resources Association》2015,51(2):421-446
An initial inquiry into model‐based numeric nitrogen and phosphorus (nutrient) criteria for large rivers is presented. Field data collection and associated modeling were conducted on a segment of the lower Yellowstone River in the northwestern United States to assess the feasibility of deriving numeric nutrient criteria using mechanistic water‐quality models. The steady‐state one‐dimensional model QUAL2K and a transect‐based companion model AT2K were calibrated and confirmed against low‐flow conditions at a time when river loadings, water column chemistry, and diurnal indicators were approximately steady state. Predictive simulation was then implemented via nutrient perturbation to evaluate the steady‐state and diurnal response of the river to incremental nutrient additions. In this first part of a two‐part series, we detail our modeling approach, model selection, calibration and confirmation, sensitivity analysis, model outcomes, and associated uncertainty. In the second part (Suplee et al., 2015) we describe the criteria development process using the tools described herein. Both articles provide a fundamental understanding of the process required to develop site‐specific numeric nutrient criteria using models in applied regulatory settings. 相似文献
34.
The dinoflagellates Scrippsiella trochoidea (Stein) and Alexandrium minutum (Halim) were grown in a light–dark cycle with nitrate or nitrate plus ammonium under three different nutrient-supply regimes
(dilution with fresh media in dark phase only or during the entire light–dark cycle at the same daily dilution rate, or with
a faster continuous dilution). When supplied with nitrate + ammonium, A. minutum released a proportion (as much as 100% from dark-fed cells) of the nitrate taken up during the dark phase as nitrite, reflecting
a rate-limiting step at nitrite reduction and poor regulation of inorganic-N uptake and assimilation. S. trochoidea released much smaller amounts of nitrite, if any. Nitrate and ammonium were not accumulated to any extent by either species
in darkness, and the transient increases in the size of the free amino acid pool were too small to explain the fate of the
newly assimilated N. Thus uptake through to incorporation of N into macromolecules appeared to be coupled in these species,
even in darkness when increasing glutamine:glutamate (Gln:Glu) ratios suggested rising C-stress. A mechanistic model was developed
from an earlier ammonium–nitrate interaction model (ANIM) by the inclusion of an internal nitrite pool, with control over
the supply of reductant for nitrite reduction linked to photosynthetic and respiratory components. The model can reproduce
the release of nitrite seen in the experiments, and also the release of nitrite in response to nitrate-feeding of N-stressed
cells reported elsewhere.
Received: 22 August 1997 / Accepted: 26 September 1997 相似文献
35.
36.
Flynn DT 《Disasters》2007,31(4):508-515
A major flood in 1997 forced the evacuation of Grand Forks, North Dakota and caused damage of USD 1 billion. Despite this recent disaster there is only marginal evidence of an increase in disaster recovery planning by businesses that experienced the flood. This finding is consistent with the results of other business-related disaster research. Statistical tests of survey results from 2003 indicate that there is a significantly higher rate of disaster recovery planning in businesses started since the 1997 flood than in businesses started before the flood and still in business. Such an outcome indicates a need for public policy actions emphasizing the importance of disaster planning. Improved disaster planning is an aid to business recovery and the results demonstrate the need for more widespread efforts to improve disaster recovery planning on the part of smaller businesses, even in areas that have recently experienced disasters. 相似文献
37.
James Flynn Barry Lefer Bernhard Rappenglück Michael Leuchner Ryan Perna Jack Dibb Luke Ziemba Casey Anderson Jochen Stutz William Brune Xinrong Ren Jingqiu Mao Winston Luke Jennifer Olson Gao Chen James Crawford 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4126-4133
A radiative transfer model and photochemical box model are used to examine the effects of clouds and aerosols on actinic flux and photolysis rates, and the impacts of changes in photolysis rates on ozone production and destruction rates in a polluted urban environment like Houston, Texas. During the TexAQS-II Radical and Aerosol Measurement Project the combined cloud and aerosol effects reduced j(NO2) photolysis frequencies by nominally 17%, while aerosols reduced j(NO2) by 3% on six clear sky days. Reductions in actinic flux due to attenuation by clouds and aerosols correspond to reduced net ozone formation rates with a nearly one-to-one relationship. The overall reduction in the net ozone production rate due to reductions in photolysis rates by clouds and aerosols was approximately 8 ppbv h?1. 相似文献
38.
Luke D. Ziemba Jack E. Dibb Robert J. Griffin Casey H. Anderson Sallie I. Whitlow Barry L. Lefer Bernhard Rappenglück James Flynn 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4081-4089
Nitrous acid (HONO), nitric acid (HNO3), and organic aerosol were measured simultaneously atop an 18-story tower in Houston, TX during August and September of 2006. HONO and HNO3 were measured using a mist chamber/ion chromatographic technique, and aerosol size and chemical composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Observations indicate the potential for a new HONO formation pathway: heterogeneous conversion of HNO3 on the surface of primary organic aerosol (POA). Significant HONO production was observed, with an average of 0.97 ppbv event?1 and a maximum increase of 2.2 ppb in 4 h. Nine identified events showed clear HNO3 depletion and well-correlated increases in both HONO concentration and POA-dominated aerosol surface area (SA). Linear regression analysis results in correlation coefficients (r2) of 0.82 for HONO/SA and 0.92 for HONO/HNO3. After correction for established HONO formation pathways, molar increases in excess HONO (HONOexcess) and decreases in HNO3 were nearly balanced, with an average HONOexcess/HNO3 value of 0.97. Deviations from this mole balance indicate that the residual HNO3 formed aerosol-phase nitrate. Aerosol mass spectral analysis suggests that the composition of POA could influence HONO production. Several previously identified aerosol-phase PAH compounds were enriched during events, suggesting their potential importance for heterogeneous HONO formation. 相似文献
39.
Nguyen Trang DT Kawai Kosuke Nakakubo Toyohiko 《Journal of Material Cycles and Waste Management》2021,23(4):1688-1697
Journal of Material Cycles and Waste Management - Implementation of waste-to-energy (WtE) incineration has recently surged in developing countries, but the drivers of this growth and the... 相似文献
40.
Functional and phylogenetic diversity as predictors of biodiversity--ecosystem-function relationships 总被引:3,自引:0,他引:3
How closely does variability in ecologically important traits reflect evolutionary divergence? The use of phylogenetic diversity (PD) to predict biodiversity effects on ecosystem functioning, and more generally the use of phylogenetic information in community ecology, depends in part on the answer to this question. However, comparisons of the predictive power of phylogenetic diversity and functional diversity (FD) have not been conducted across a range of experiments. To address how phylogenetic diversity and functional trait variation control biodiversity effects on biomass production, we summarized the results of 29 grassland plant experiments where both the phylogeny of plant species used in the experiments is well described and where extensive trait data are available. Functional trait variation was only partially related to phylogenetic distances between species, and the resulting FD values therefore correlate only partially with PD. Despite these differences, FD and PD predicted biodiversity effects across all experiments with similar strength, including in subsets that excluded plots with legumes and that focused on fertilization experiments. Two- and three-trait combinations of the five traits used here (leaf nitrogen percentage, height, specific root length, leaf mass per unit area, and nitrogen fixation) resulted in the FD values with the greatest predictive power. Both PD and FD can be valuable predictors of the effect of biodiversity on ecosystem functioning, which suggests that a focus on both community trait diversity and evolutionary history can improve understanding of the consequences of biodiversity loss. 相似文献