全文获取类型
收费全文 | 474篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 10篇 |
废物处理 | 7篇 |
环保管理 | 84篇 |
综合类 | 106篇 |
基础理论 | 73篇 |
污染及防治 | 165篇 |
评价与监测 | 27篇 |
社会与环境 | 6篇 |
灾害及防治 | 5篇 |
出版年
2023年 | 4篇 |
2018年 | 18篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 57篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 9篇 |
2009年 | 13篇 |
2008年 | 15篇 |
2007年 | 18篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 8篇 |
2003年 | 11篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 11篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1968年 | 4篇 |
1965年 | 3篇 |
1964年 | 3篇 |
1957年 | 3篇 |
1955年 | 6篇 |
1954年 | 3篇 |
1939年 | 5篇 |
排序方式: 共有483条查询结果,搜索用时 31 毫秒
51.
52.
53.
Karen R. Hall Jean Spooner Robert J. Richardson Steve T. Hoyle Douglas J. Frederick 《Journal of the American Water Resources Association》2014,50(3):533-542
Microstegium vimineum is an invasive grass introduced from Asia that has spread throughout riparian areas of the eastern United States threatening native riparian vegetation. Postemergence (POST) herbicides registered for aquatic use were evaluated for control of M. vimineum on two riparian restoration sites in the Piedmont and Upper Coastal Plain of North Carolina. This study found that standard and lower than standard rates of diquat, fluridone, flumioxazin, glyphosate, imazamox, and imazapyr reduced weed stem density and biomass at 6 and 30 weeks after treatment (WAT). Both rates of bispyribac and penoxsulam provided less control of M. vimineum. Visual ratings showed both rates of diquat, flumioxazin, imazamox, and imazapyr controlled 63‐100% of M. vimineum at 6 WAT and 84‐100% at 30 WAT. Fluridone and glyphosate provided slightly less control. Bispyribac and penoxsulam treatments provided less control at 6 and 30 WAT compared to the other treatments. Plots treated with both rates of diquat, flumioxazin, imazamox, and imazapyr were nearly devoid of all vegetation at 30 WAT. Recommendations include POST application of lower than standard rates of diquat, flumioxazin, fluridone, glyphosate, imazamox, and imazapyr on riparian restoration sites infested with M. vimineum. Immediate vegetation management measures including temporary and permanent plant cover should be employed on treated sites where weeds are completely eradicated to prevent erosion. 相似文献
54.
Nathan J. Waltham Michael Barry Tony McAlister Tony Weber Dominic Groth 《Environmental management》2014,54(4):840-851
The Gold Coast City is the tourist center of Australia and has undergone rapid and massive urban expansion over the past few decades. The Broadwater estuary, in the heart of the City, not only offers an array of ecosystems services for many important aquatic wildlife species, but also supports the livelihood and lifestyles of residents. Not surprisingly, there have been signs of imbalance between these two major services. This study combined a waterway hydraulic and pollutant transport model to simulate diffuse nutrient and sediment loads under past and future proposed land-use changes. A series of catchment restoration initiatives were modeled in an attempt to define optimal catchment scale restoration efforts necessary to protect and enhance the City’s waterways. The modeling revealed that for future proposed development, a business as usual approach to catchment management will not reduce nutrient and sediment loading sufficiently to protect the community values. Considerable restoration of upper catchment tributaries is imperative, combined with treatment of stormwater flow from intensively developed sub-catchment areas. Collectively, initiatives undertaken by regulatory authorities to date have successfully reduced nutrient and sediment loading reaching adjoining waterways, although these programs have been ad hoc without strategic systematic planning and vision. Future conservation requires integration of multidisciplinary science and proactive management driven by the high ecological, economical, and community values placed on the City’s waterways. Long-term catchment restoration and conservation planning requires an extensive budget (including political and societal support) to handle ongoing maintenance issues associated with scale of restoration determined here. 相似文献
55.
José A. P. Marcelino Everett Weber Luís Silva Patrícia V. Garcia António O. Soares 《Environmental management》2014,54(5):1121-1130
Human influence associated with land use may cause considerable biodiversity losses, namely in oceanic islands such as the Azores. Our goal was to identify plant indicator species across two gradients of increasing anthropogenic influence and management (arborescent and herbaceous communities) and determine similarity between plant communities of uncategorized vegetation plots to those in reference gradients using metrics derived from R programming. We intend to test and provide an expedient way to determine the conservation value of a given uncategorized vegetation plot based on the number of native, endemic, introduced, and invasive indicator species present. Using the metric IndVal, plant taxa with a significant indicator value for each community type in the two anthropogenic gradients were determined. A new metric, ComVal, was developed to assess the similarity of an uncategorized vegetation plot toward a reference community type, based on (i) the percentage of pre-defined indicator species from reference communities present in the vegetation plots, and (ii) the percentage of indicator species, specific to a given reference community type, present in the vegetation plot. Using a data resampling approach, the communities were randomly used as training or validation sets to classify vegetation plots based on ComVal. The percentage match with reference community types ranged from 77 to 100 % and from 79 to 100 %, for herbaceous and arborescent vegetation plots, respectively. Both IndVal and ComVal are part of a suite of useful tools characterizing plant communities and plant community change along gradients of anthropogenic influence without a priori knowledge of their biology and ecology. 相似文献
56.
57.
Thomas Knoke Michael Weber 《Mitigation and Adaptation Strategies for Global Change》2006,11(3):579-605
The study presents a comprehensive methodology for the appraisal of C-stock expansion in existing forests as a forest management
activity according to Art. 3.4 of the Kyoto Protocol. It allows for producer costs of carbon sequestration in forest enterprises
to be derived. The methodology is based on a non-linear programming approach considering economic optimisation as well as
ecological, social and sustainability needs through constraints and risk integration. While introducing further constraints
on carbon stocks, the carbon stored in forest biomass was increased in periodic increments. However, while extending the carbon
stocks, the ecological and social constraints as well as sustainability requirements are not to be violated. Costs were derived
for every additional Mg (Megagrams) of C per ha sequestered in comparison to a baseline management.
Two basic cases were considered: First, a permanent carbon sequestration was assumed. Secondly, a temporary storage of additional
carbon over 10 years was supposed. The potential willingness of buyers of carbon certificates to pay for temporary carbon
sequestration was derived by a financial consideration. We assumed that, for a buyer, the value of a temporary carbon sequestration
certificate would be equivalent to the return on the savings because an investment in technical measures on reduction of carbon
emissions can be postponed. 相似文献
58.
Peter Frederick 《Behavioral ecology and sociobiology》1987,21(4):223-228
Summary I intensively observed the mating behavior of 134 pairs of white ibises for over 15 000 pair hours to examine the responses of males to extrapair copulations (EPC) involving their mates. Females often cooperated completely in apparently fertile EPCs. Male mate-guarding was vigorous and effective. Males did not respond to apparent sperm competition with forced-pair copulation, physical punishment, or abandonment of their mates. I found no negative correlation between degree of female promiscuity and the amount of parental care her mate gave to the entire brood. Males also did not reduce paternal care given to the young most likely to be the result of an EPC. I hypothesize that males are constrained in the behaviors they can use to avoid misplaced paternity in this species. While male mate-guarding reduces the opportunities for female involvement in EPC, the behaviors used by males to protect paternity apparently have not prevented the evolution of female receptiveness during EPC attempts. 相似文献
59.
60.
Second trimester amniocentesis has traditionally been utilized for prenatal genetic diagnosis. Chorionic villi sampling (CVS) is presently offered as an alternative. The occurrence of fetomaternal bleed (FMB) during CVS could increase the rate of post sampling abortion and, additionally, be of significance in patients at risk for isoimmunization. Detection and quantitation of FMB can be accomplished by the determination of changes in maternal serum alpha-fetoprotein (MSAFP) before and after CVS. 相似文献