全文获取类型
收费全文 | 325篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 13篇 |
废物处理 | 18篇 |
环保管理 | 61篇 |
综合类 | 37篇 |
基础理论 | 91篇 |
环境理论 | 3篇 |
污染及防治 | 81篇 |
评价与监测 | 16篇 |
社会与环境 | 15篇 |
灾害及防治 | 6篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 15篇 |
2016年 | 22篇 |
2015年 | 9篇 |
2014年 | 9篇 |
2013年 | 19篇 |
2012年 | 17篇 |
2011年 | 18篇 |
2010年 | 14篇 |
2009年 | 12篇 |
2008年 | 29篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 12篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有341条查询结果,搜索用时 78 毫秒
71.
Morano JL Rice AN Tielens JT Estabrook BJ Murray A Roberts BL Clark CW 《Conservation biology》2012,26(4):698-707
Species' conservation relies on understanding their seasonal habitats and migration routes. North Atlantic right whales (Eubalaena glacialis), listed as endangered under the U.S. Endangered Species Act, migrate from the southeastern U.S. coast to Cape Cod Bay, Massachusetts, a federally designated critical habitat, from February through May to feed. The whales then continue north across the Gulf of Maine to northern waters (e.g., Bay of Fundy). To enter Cape Cod Bay, right whales must traverse an area of dense shipping and fishing activity in Massachusetts Bay, where there are no mandatory regulations for the protection of right whales or management of their habitat. We used passive acoustic recordings of right whales collected in Massachusetts Bay from May 2007 through October 2010 to determine the annual spatial and temporal distribution of the whales and their calling activity. We detected right whales in the bay throughout the year, in contrast to results from visual surveys. Right whales were detected on at least 24% of days in each month, with the exception of June 2007, in which there were no detections. Averaged over all years, right whale calls were most abundant from February through May. During this period, calls were most frequent between 17:00 and 20:00 local time; no diel pattern was apparent in other months. The spatial distribution of the approximate locations of calling whales suggests they may use Massachusetts Bay as a conduit to Cape Cod Bay in the spring and as they move between the Gulf of Maine and waters to the south in September through December. Although it is unclear how dependent right whales are on the bay, the discovery of their widespread presence in Massachusetts Bay throughout the year suggests this region may need to be managed to reduce the probability of collisions with ships and entanglement in fishing gear. 相似文献
72.
Woody plant encroachment is a worldwide phenomenon in grassland and savanna systems whose consequence is often the development of an alternate woodland state. Theoretically, an alternate state may be associated with changes in system state variables (e.g., species composition) or abiotic parameter shifts (e.g., nutrient availability). When state-variable changes are cumulative, such as in woody plant encroachment, the probability of parameter shifts increases as system feedbacks intensify over time. Using a Before-After Control-Impact (BACI) design, we studied eight pairs of grassland sites undergoing various levels of eastern redcedar (Juniperus virginiana) encroachment to determine whether responses of flora and fauna to experimental redcedar removal differed according to the level of pretreatment redcedar cover. In the first year after removal, herbaceous plant species diversity and evenness, woody plant evenness, and invertebrate family richness increased linearly with pretreatment redcedar cover, whereas increases in small-mammal diversity and evenness were described by logarithmic trends. In contrast, increases in woody plant diversity and total biomass of terrestrial invertebrates were accentuated at levels of higher pretreatment cover. Tree removal also shifted small-mammal species composition toward a more grassland-associated assemblage. During the second year postremoval, increases in herbaceous plant diversity followed a polynomial trend, but increases in most other metrics did not vary along the pretreatment cover gradient. These changes were accompanied by extremely high growing-season precipitation, which may have homogenized floral and faunal responses to removal. Our results demonstrate that tree removal increases important community metrics among grassland flora and fauna within two years, with some responses to removal being strongly influenced by the stage of initial encroachment and modulated by climatic variability. Our results underscore the importance of decisive management for reversing the effects of woody plant encroachment in imperiled grassland ecosystems. 相似文献
73.
Bailey?C.?McMeansEmail author Michael?T.?Arts Scott?A.?Rush Aaron?T.?Fisk 《Marine Biology》2012,159(5):1095-1105
The marine copepod Calanus hyperboreus accumulates large quantities of lipids and essential fatty acids during summer months in Northern oceans. However, few data
exist regarding their winter fatty acid profiles, which could be informative regarding the use of lipids by C. hyperboreus to successfully survive and reproduce during times of ice-cover and limited food. The present study compared fatty acids
of C. hyperboreus between summer (August 2007 and 2008) and winter (early April 2008 and 2009) in Cumberland Sound, Canada. Summer samples
from both years had significantly higher ∑polyunsaturated fatty acids and unsaturation indices (based on μg fatty acid mg
dry tissue−1) than winter samples and separated on a principal component analysis due to higher 18:2n-6, 18:4n-3, and 20:5n-3, consistent
with phytoplankton consumption. Winter C. hyperboreus had significantly higher ∑monounsaturated fatty acids (MUFA) versus summer samples and separated on the principal component
analysis due to higher proportions of 16:1n-7, 20:1n-9, and 22:1n-9, suggesting they were not actively feeding. Based on the
seasonal fatty acid comparison, C. hyperboreus was catabolizing specific fatty acids (e.g. 20:5n-3), conserving others (e.g. 22:6n-3), and maintaining or increasing biosynthesis
of certain MUFA (e.g. 18:1n-9) during winter. These findings provide insight into the seasonal strategy of acquisition (summer)
and utilization (winter) of specific fatty acids by a key Arctic organism and could become important for monitoring changes
in fatty acids associated with decreased ice-cover duration due to climate warming. 相似文献
74.
David Natcher Vijayalakshmi Kalagnanam Ramesh Rawal Mark Johnston Abdullah Al Mamun 《国际发展与全球生态学杂志》2018,25(1):47-55
This paper presents the results of research conducted between 2009 and 2014 in the village of Khanda Sharol in the state of Rajasthan, India. Our research objective was to determine how the livelihoods of village residents have been affected by the intensification of forest use, and the resulting loss of domestic access to traditionally used forest resources. Results indicate that changes in forest cover have resulted in a loss of livelihood options for village residents. Yet rather than being victimized by environmental change processes, this paper shows how villagers have responded by partnering with public and private actors to develop a community protected forest area that is now helping villagers to meet their livelihood needs. These findings suggest that sustainable livelihoods in rural regions of India require committed and scaled approaches involving local, public, and private actors. 相似文献
75.
We explored the interacting effects of marine-derived nutrient fertilization and physical disturbance introduced by coastal river otters (Lontra canadensis) on the production and nutrient status of pristine shrub and tree communities in Prince William Sound, Alaska, USA. We compared production of trees and shrubs between latrines and non-latrines, while accounting for otter site selection, by sampling areas on and off sites. Nitrogen stable isotope analysis (delta15N) indicated that dominant tree and shrub species assimilated the marine-derived N excreted by otters. In association with this uptake, tree production increased, but shrub density and nonwoody aboveground shrub production decreased. The reduced shrub production was caused by destruction of ramets, especially blueberry (Vaccinium spp.), through physical disturbance by river otters. False azalea (Menziesia ferruginea) ramets were less sensitive to otter disturbance. Although surviving individual blueberry ramets showed a tendency for increased production per plant, false azalea allocated excess N to storage in leaves rather than growth. We found that plant responses to animal activity vary among species and levels of biological organization (leaf, plant, ecosystem). Such differences should be accounted for when assessing the influence of river otters on the carbon budget of Alaskan coastal forests at the landscape scale. 相似文献
76.
Javier delBarco-Trillo M. E. McPhee Robert E. Johnston 《Behavioral ecology and sociobiology》2010,64(8):1247-1253
When females mate with a heterospecific male, they do not usually produce viable offspring. Thus, there is a selective pressure
for females to avoid interspecific mating. In many species, females innately avoid heterospecific males; females can also
imprint on their parents to avoid later sexual interactions with heterospecific males. However, it was previously unknown
whether adult females can learn to discriminate against heterospecific males. We tested the hypothesis that adult females
previously unable to avoid interspecific mating learn to avoid such mating after being exposed to heterospecific males. Syrian
hamster (Mesocricetus auratus) females not previously exposed to Turkish hamster (Mesocricetus brandti) males can discriminate between odors of conspecific and heterospecific males, but they mate with either type of male. However,
when we exposed adult females to both a conspecific male and a heterospecific male through wire-mesh barriers for 8 days,
and then paired them sequentially with the two males, females were more receptive to conspecific males and more aggressive
to heterospecific males. When females were paired with the heterospecific male first and the conspecific male second, no female
was receptive and all were aggressive to heterospecific males. When females were paired with the conspecific male first, only
43% of females were then aggressive toward the heterospecific male. That is, interactions with conspecific males may decrease
a female’s ability to properly avoid heterospecific males. Our study clearly shows for the first time that females can learn
during adulthood to avoid interspecific mating just by being exposed to stimuli from heterospecific males. 相似文献
77.
Cribb BW Stewart A Huang H Truss R Noller B Rasch R Zalucki MP 《Die Naturwissenschaften》2008,95(5):433-441
Previously, the presence of metals in arthropod mandibles has been linked with harder cuticle, and in termites, a 20% increase in hardness has been found for mandibles containing major quantities of zinc. The current study utilises electron microscopy and energy-dispersive X-ray microanalysis to assess incidence and abundance of metals in all extant subfamilies of the Isoptera. The basal clades contain no zinc and little to no manganese in the cutting edge of the mandible cuticle, suggesting that these states are ancestral for termites. However, experimentation with mandibles in vitro indicates the presence of some elements of the cuticular biochemistry necessary to enable uptake of zinc. The Termopsidae, Serritermitidae, Rhinotermitidae and Termitidae all contain minor quantities of manganese, while trace to minor quantities of zinc occur in all except the Serritermitidae. In contrast, all Kalotermitidae or drywood termites contain major levels of zinc in the mandible edge. Diet and life type are explored as links to metal profiles across the termites. The presence of harder mandibles in the drywood termites may be related to lack of access to free water with which to moisten wood. Scratch tests were applied to a set of mandibles. The coefficient of friction for Cryptotermes primus (Kalotermitidae) mandibles, when compared with species from other subfamilies, indicates that zinc-containing mandibles are likely to be more scratch resistant. 相似文献
78.
Thi Thu Nga PhamHuu Hao Ngo Wenshan GuoHo Phuong Dung Dang Bandita MainaliArchie Johnston Andrzej Listowski 《Resources, Conservation and Recycling》2011,55(5):535-540
Recycled water is a valuable resource that has potential to free up potable water supplies and recharge systems while improving the environment. Recycled water for washing machine could be one of the options as new end use of recycled water to alleviate the demand on existing and limited water supplies. This paper summarizes the findings of a research survey in Sydney, Australia to explore the attitudes and opinions of community towards the use of recycled water for different purposes, especially for the washing machine. The survey showed that 97% of the respondents were aware of the persisting water shortage problem while more than 60% of the respondents supported the use of recycled water for washing clothes. This paper exposes the basic concern of participants for using recycled water in washing machine. Health issue was found as the most concerns of the community. The survey also presents the further conditions to be considered for using recycled water for washing machine according to the participants’ opinions. Correlation between knowledge and attitudes of respondents was also found in this survey. 相似文献
79.
Richard B. Moore Craig M. Johnston Richard A. Smith Bryan Milstead 《Journal of the American Water Resources Association》2011,47(5):965-990
Moore, Richard B., Craig M. Johnston, Richard A. Smith, and Bryan Milstead, 2011. Source and Delivery of Nutrients to Receiving Waters in the Northeastern and Mid‐Atlantic Regions of the United States. Journal of the American Water Resources Association (JAWRA) 47(5):965‐990. DOI: 10.1111/j.1752‐1688.2011.00582.x Abstract: This study investigates nutrient sources and transport to receiving waters, in order to provide spatially detailed information to aid water‐resources managers concerned with eutrophication and nutrient management strategies. SPAtially Referenced Regressions On Watershed attributes (SPARROW) nutrient models were developed for the Northeastern and Mid‐Atlantic (NE US) regions of the United States to represent source conditions for the year 2002. The model developed to examine the source and delivery of nitrogen to the estuaries of nine large rivers along the NE US Seaboard indicated that agricultural sources contribute the largest percentage (37%) of the total nitrogen load delivered to the estuaries. Point sources account for 28% while atmospheric deposition accounts for 20%. A second SPARROW model was used to examine the sources and delivery of phosphorus to lakes and reservoirs throughout the NE US. The greatest attenuation of phosphorus occurred in lakes that were large relative to the size of their watershed. Model results show that, within the NE US, aquatic decay of nutrients is quite limited on an annual basis and that we especially cannot rely on natural attenuation to remove nutrients within the larger rivers nor within lakes with large watersheds relative to the size of the lake. 相似文献
80.
Kani Alexander Nti Dovi Evans Mpatani Farid Mzee Aryee Aaron Albert Han Runping Li Zhaohui Qu Lingbo 《Environmental Chemistry Letters》2022,20(1):705-729
Environmental Chemistry Letters - The direct discharge of untreated contaminants into global water systems has jeopardized our water security worldwide. This environmental concern has prompted... 相似文献