全文获取类型
收费全文 | 3051篇 |
免费 | 43篇 |
国内免费 | 25篇 |
专业分类
安全科学 | 163篇 |
废物处理 | 154篇 |
环保管理 | 615篇 |
综合类 | 352篇 |
基础理论 | 733篇 |
环境理论 | 5篇 |
污染及防治 | 760篇 |
评价与监测 | 212篇 |
社会与环境 | 106篇 |
灾害及防治 | 19篇 |
出版年
2023年 | 25篇 |
2022年 | 37篇 |
2021年 | 26篇 |
2020年 | 21篇 |
2019年 | 31篇 |
2018年 | 66篇 |
2017年 | 67篇 |
2016年 | 90篇 |
2015年 | 58篇 |
2014年 | 86篇 |
2013年 | 281篇 |
2012年 | 144篇 |
2011年 | 177篇 |
2010年 | 120篇 |
2009年 | 124篇 |
2008年 | 155篇 |
2007年 | 187篇 |
2006年 | 153篇 |
2005年 | 105篇 |
2004年 | 105篇 |
2003年 | 119篇 |
2002年 | 89篇 |
2001年 | 68篇 |
2000年 | 46篇 |
1999年 | 52篇 |
1998年 | 39篇 |
1997年 | 43篇 |
1996年 | 44篇 |
1995年 | 40篇 |
1994年 | 41篇 |
1993年 | 34篇 |
1992年 | 37篇 |
1991年 | 26篇 |
1990年 | 29篇 |
1989年 | 19篇 |
1988年 | 13篇 |
1987年 | 20篇 |
1986年 | 25篇 |
1985年 | 17篇 |
1984年 | 18篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 25篇 |
1980年 | 19篇 |
1979年 | 16篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 10篇 |
1971年 | 11篇 |
排序方式: 共有3119条查询结果,搜索用时 15 毫秒
991.
992.
Long Ngo Louise M. Ryan Maura Mezzetti Frédéric Y. Bois Thomas J. Smith 《Environmental and Ecological Statistics》2011,18(1):131-146
In a study of 133 volunteer subjects, demographic, physiologic and pharmacokinetic data through exposure to 1,3-Butadiene
(BD) were collected in order to estimate the percentage of BD concentration metabolized at steady state, and to determine
whether this percentage varies across gender, racial, and age groups. During the 20 min of continuous exposure to 2 parts
per million (ppm) of BD, five measurements of exhaled concentration were made on each subject. In the following 40 min washout
period, another five measurements were collected. A Bayesian hierarchical compartmental physiologically-based pharmacokinetic
model (PKPB) was used. Using prior information on the model parameters, Markov Chain Monte Carlo (MCMC) simulation was conducted
to obtain posterior distributions. The overall estimate of the mean percent of BD metabolized at steady state was 12.7% (95%
credible interval: 7.7–17.8%). There was no significant difference in gender with males having a mean of 13.5%, and females
12.3%. Among the racial groups, Hispanic (13.9%), White (13.0%), Asian (12.1%), and Black (10.9%), the significant difference
came from the difference between Black and Hispanic with a 95% credible interval from −5.63 to −0.30%. Those older than 30 years
had a mean of 12.2% versus 12.9% for the younger group; although this was not a statistically significant difference. Given
a constant inhalation input of 2 ppm, at steady state, the overall mean exhaled concentration was estimated to be 1.75ppm
(95% credible interval: 1.64–1.84). An equivalent parameter, first-order metabolic rate constant, was also estimated and found
to be consistent with the percent of BD metabolized at steady state across gender, race, and age strata. 相似文献
993.
Evidence of inbreeding depression is commonly detected from the fitness traits of animals, yet its effects on population growth rates of endangered species are rarely assessed. We examined whether inbreeding depression was affecting Sierra Nevada bighorn sheep (Ovis canadensis sierrae), a subspecies listed as endangered under the U.S. Endangered Species Act. Our objectives were to characterize genetic variation in this subspecies; test whether inbreeding depression affects bighorn sheep vital rates (adult survival and female fecundity); evaluate whether inbreeding depression may limit subspecies recovery; and examine the potential for genetic management to increase population growth rates. Genetic variation in 4 populations of Sierra Nevada bighorn sheep was among the lowest reported for any wild bighorn sheep population, and our results suggest that inbreeding depression has reduced adult female fecundity. Despite this population sizes and growth rates predicted from matrix-based projection models demonstrated that inbreeding depression would not substantially inhibit the recovery of Sierra Nevada bighorn sheep populations in the next approximately 8 bighorn sheep generations (48 years). Furthermore, simulations of genetic rescue within the subspecies did not suggest that such activities would appreciably increase population sizes or growth rates during the period we modeled (10 bighorn sheep generations, 60 years). Only simulations that augmented the Mono Basin population with genetic variation from other subspecies, which is not currently a management option, predicted significant increases in population size. Although we recommend that recovery activities should minimize future losses of genetic variation, genetic effects within these endangered populations-either negative (inbreeding depression) or positive (within subspecies genetic rescue)-appear unlikely to dramatically compromise or stimulate short-term conservation efforts. The distinction between detecting the effects of inbreeding depression on a component vital rate (e.g., fecundity) and the effects of inbreeding depression on population growth underscores the importance of quantifying inbreeding costs relative to population dynamics to effectively manage endangered populations. 相似文献
994.
Lars Hendrik Simon Volker Wilkens Thomas Fedtke Michael Beyer 《Journal of Loss Prevention in the Process Industries》2013,26(6):1583-1589
This paper shows the results of our investigations on the ignition source ultrasound in dust-air atmospheres. Ultrasound is, on the one hand, considered to be an ignition source according to international safety standards (EN 1127–1 (2011)). On the other hand, though, ultrasound is used for various applications in gases and air, such as level and flow measurement, or in the process industry, but no explosion accidents have yet been reported. Our research now shows that it is indeed possible to ignite dust-air mixtures in ultrasound fields under certain conditions. We conducted our experiments in an ultrasound standing wave field and used maize starch, calcium stearate and sulfur dust. For ignitions, an absorbing target was needed to convert the acoustic energy into heat. From theoretical estimations and experiments critical conditions that provoke ultrasonically triggered explosions are identified. 相似文献
995.
Anil Acharya Kenneth Lamb Thomas C. Piechota 《Journal of the American Water Resources Association》2013,49(2):359-370
Abstract: Climate change, particularly the projected changes to precipitation patterns, is likely to affect runoff both regionally and temporally. Extreme rainfall events are expected to become more intense in the future in arid urban areas and this will likely lead to higher streamflow. Through hydrological modeling, this article simulates an urban basin response to the most intense storm under anthropogenic climate change conditions. This study performs an event‐based simulation for shorter duration storms in the Flamingo Tropicana (FT) watershed in Las Vegas, Nevada. An extreme storm, defined as a 100‐year return period storm, is selected from historical records and perturbed to future climatic conditions with respect to multimodel multiscenario (A1B, A2, B1) bias corrected and spatially disaggregated data from the World Climate Research Programme's (WCRP's) database. The cumulative annual precipitation for each 30‐year period shows a continuous decrease from 2011 to 2099; however, the summer convective storms, which are considered as extreme storms for the study area, are expected to be more intense in future. Extreme storm events show larger changes in streamflow under different climate scenarios and time periods. The simulated peak streamflow and total runoff volume shows an increase from 40% to more than 150% (during 2041‐2099) for different climate scenarios. This type of analysis can help evaluate the vulnerability of existing flood control system and flood control policies. 相似文献
996.
Heidelore Fiedler Mohammad Sadia Thomas Krauss Abeer Baabish Leo W.Y. Yeung 《Frontiers of Environmental Science & Engineering》2022,16(10):132
997.
Ehlers Sonja M. Al Najjar Tamara Taupp Thomas Koop Jochen H. E. 《Environmental science and pollution research international》2020,27(18):22380-22389
Environmental Science and Pollution Research - Caddisfly larvae occur in streams and rivers, and many caddisfly species build protective cases using material from their habitat such as sand grains.... 相似文献
998.
S. Laufs G. Burgeth W. Duttlinger R. Kurtenbach M. Maban C. Thomas P. Wiesen J. Kleffmann 《Atmospheric environment (Oxford, England : 1994)》2010,44(19):2341-2349
In the present study, photocatalytic reactions of nitrogen oxides (NOx = NO + NO2) were studied on commercial TiO2 doped facade paints in a flow tube photoreactor under simulated atmospheric conditions. Fast photocatalytic conversion of NO and NO2 was observed only for the photocatalytic paints and not for non-catalytic reference paints. Nitrous acid (HONO) was formed in the dark on all paints studied, however, it efficiently decomposes under irradiation only on the photocatalytic samples. Thus, it is concluded that photocatalytic paint surfaces do not represent a daytime source of HONO, in contrast to other recent studies on pure TiO2 surfaces. As main final product, the formation of adsorbed nitric acid/nitrate anion (HNO3/NO3?) was observed with near to unity yield. In addition, traces of H2O2 were observed in the gas phase only in the presence of O2. Formation of the greenhouse gas nitrous oxide (N2O) could be excluded. The uptake kinetics of NO, NO2 and HONO was very fast under atmospheric conditions (e.g. γ(NO + TiO2) > 10?5). Thus, the uptake on urban surfaces (painted houses, etc.) will be limited by transport. For a hypothetically painted street canyon, an average reduction of nitrogen oxide levels of ca. 5% is estimated. Since the harmful HNO3/NO3? is formed on the surface of the photoactive paints, whereas it is formed in the gas phase in the atmosphere, the use of photocatalytic paints may also help to reduce acid deposition, e.g. on plants, or nitric acid related health issues. 相似文献
999.
Kolpin DW Hoerger CC Meyer MT Wettstein FE Hubbard LE Bucheli TD 《Journal of environmental quality》2010,39(6):2089-2099
This study provides the first broad-scale investigation on the spatial and temporal occurrence of phytoestrogens and mycotoxins in streams in the United States. Fifteen stream sites across Iowa were sampled five times throughout the 2008 growing season to capture a range of climatic and crop-growth conditions. Basin size upstream from sampling sites ranged from 7 km2 to > 836,000 km2. Atrazine (herbicide) also was measured in all samples as a frame-of-reference agriculturally derived contaminant. Target compounds were frequently detected in stream samples: atrazine (100%), formononetin (80%), equol (45%), deoxynivalenol (43%), daidzein (32%), biochanin A (23%), zearalenone (13%), and genistein (11%). The nearly ubiquitous detection of formononetin (isoflavone) suggests a widespread agricultural source, as one would expect with the intense row crop and livestock production present across Iowa. Conversely, the less spatially widespread detections of deoxynivalenol (mycotoxin) suggest a more variable source due to the required combination of proper host and proper temperature and moisture conditions necessary to promote Fusarium spp. infections. Although atrazine concentrations commonly exceeded 100 ng L(-1) (42/75 measurements), only deoxynivalenol (6/56 measurements) had concentrations that occasionally exceeded this level. Temporal patterns in concentrations varied substantially between atrazine, formononetin, and deoxynivalenol, as one would expect for contaminants with different source inputs and processes of formation and degradation. The greatest phytoestrogen and mycotoxin concentrations were observed during spring snowmelt conditions. Phytoestrogens and mycotoxins were detected at all sampling sites regardless of basin size. The ecotoxicological effects from long-term, low-level exposures to phytoestrogens and mycotoxins or complex chemicals mixtures including these compounds that commonly rake place in surface water are poorly understood and have yet to be systematically investigated in environmental studies. 相似文献
1000.
Modeling the Relations Between Flow Regime Components,Species Traits,and Spawning Success of Fishes in Warmwater Streams 总被引:1,自引:0,他引:1
Scott W. Craven James T. Peterson Mary C. Freeman Thomas J. Kwak Elise Irwin 《Environmental management》2010,46(2):181-194
Modifications to stream hydrologic regimes can have a profound influence on the dynamics of their fish populations. Using
hierarchical linear models, we examined the relations between flow regime and young-of-year fish density using fish sampling
and discharge data from three different warmwater streams in Illinois, Alabama, and Georgia. We used an information theoretic
approach to evaluate the relative support for models describing hypothesized influences of five flow regime components representing:
short-term high and low flows; short-term flow stability; and long-term mean flows and flow stability on fish reproductive
success during fish spawning and rearing periods. We also evaluated the influence of ten fish species traits on fish reproductive
success. Species traits included spawning duration, reproductive strategy, egg incubation rate, swimming locomotion morphology,
general habitat preference, and food habits. Model selection results indicated that young-of-year fish density was positively
related to short-term high flows during the spawning period and negatively related to flow variability during the rearing
period. However, the effect of the flow regime components varied substantially among species, but was related to species traits.
The effect of short-term high flows on the reproductive success was lower for species that broadcast their eggs during spawning.
Species with cruiser swimming locomotion morphologies (e.g., Micropterus) also were more vulnerable to variable flows during the rearing period. Our models provide insight into the conditions and
timing of flows that influence the reproductive success of warmwater stream fishes and may guide decisions related to stream
regulation and management. 相似文献