全文获取类型
收费全文 | 1389篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 25篇 |
废物处理 | 19篇 |
环保管理 | 128篇 |
综合类 | 1004篇 |
基础理论 | 93篇 |
污染及防治 | 100篇 |
评价与监测 | 20篇 |
社会与环境 | 6篇 |
灾害及防治 | 3篇 |
出版年
2016年 | 10篇 |
2013年 | 55篇 |
2012年 | 11篇 |
2011年 | 15篇 |
2010年 | 18篇 |
2009年 | 8篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 20篇 |
2002年 | 10篇 |
1998年 | 12篇 |
1995年 | 59篇 |
1994年 | 51篇 |
1993年 | 42篇 |
1992年 | 37篇 |
1991年 | 26篇 |
1990年 | 33篇 |
1989年 | 28篇 |
1988年 | 34篇 |
1987年 | 29篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 14篇 |
1983年 | 19篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1976年 | 9篇 |
1975年 | 10篇 |
1973年 | 11篇 |
1965年 | 8篇 |
1962年 | 9篇 |
1961年 | 8篇 |
1959年 | 9篇 |
1957年 | 13篇 |
1955年 | 8篇 |
1940年 | 10篇 |
1939年 | 10篇 |
1937年 | 9篇 |
1935年 | 11篇 |
1934年 | 7篇 |
1919年 | 47篇 |
1918年 | 44篇 |
1917年 | 36篇 |
1916年 | 53篇 |
1915年 | 37篇 |
1914年 | 71篇 |
1913年 | 106篇 |
排序方式: 共有1398条查询结果,搜索用时 556 毫秒
81.
82.
Limits and dynamics of methane oxidation in landfill cover soils 总被引:1,自引:0,他引:1
In order to understand the limits and dynamics of methane (CH4) oxidation in landfill cover soils, we investigated CH4 oxidation in daily, intermediate, and final cover soils from two California landfills as a function of temperature, soil moisture and CO2 concentration. The results indicate a significant difference between the observed soil CH4 oxidation at field sampled conditions compared to optimum conditions achieved through pre-incubation (60 days) in the presence of CH4 (50 ml l−1) and soil moisture optimization. This pre-incubation period normalized CH4 oxidation rates to within the same order of magnitude (112-644 μg CH4 g−1 day−1) for all the cover soils samples examined, as opposed to the four orders of magnitude variation in the soil CH4 oxidation rates without this pre-incubation (0.9-277 μg CH4 g−1 day−1).Using pre-incubated soils, a minimum soil moisture potential threshold for CH4 oxidation activity was estimated at 1500 kPa, which is the soil wilting point. From the laboratory incubations, 50% of the oxidation capacity was inhibited at soil moisture potential drier than 700 kPa and optimum oxidation activity was typical observed at 50 kPa, which is just slightly drier than field capacity (33 kPa). At the extreme temperatures for CH4 oxidation activity, this minimum moisture potential threshold decreased (300 kPa for temperatures <5 °C and 50 kPa for temperatures >40 °C), indicating the requirement for more easily available soil water. However, oxidation rates at these extreme temperatures were less than 10% of the rate observed at more optimum temperatures (∼30 °C). For temperatures from 5 to 40 °C, the rate of CH4 oxidation was not limited by moisture potentials between 0 (saturated) and 50 kPa. The use of soil moisture potential normalizes soil variability (e.g. soil texture and organic matter content) with respect to the effect of soil moisture on methanotroph activity. The results of this study indicate that the wilting point is the lower moisture threshold for CH4 oxidation activity and optimum moisture potential is close to field capacity.No inhibitory effects of elevated CO2 soil gas concentrations were observed on CH4 oxidation rates. However, significant differences were observed for diurnal temperature fluctuations compared to thermally equivalent daily isothermal incubations. 相似文献
83.
84.
Kurt E. Richardson Nelson A. Cox Doug E. Cosby Mark E. Berrang Nicole L. Holcombe Cheryl E. Weller 《Journal of environmental science and health. Part. B》2019,54(4):313-316
The pH of Salmonella pre-enrichment media can become acidic (pH 4.0–5.0) when feeds/ingredients are incubated for 24?h. Salmonella in feed that have been stressed by heat and desiccation exhibit different pH tolerances than non-stressed cultures. Acidic conditions can result in cell injury/death and affect biochemical pathways. In this study, eight serotypes of Salmonella were grown in sterile meat and bone meal that was subjected to desiccation and heat stress. Cultures of non-stressed and stressed isolates were subsequently exposed to acidic pH from 4.0 to 7.0 in 0.5?pH increments (3 replicates/pH increment) in citrate buffer. At 6 and 24?h, serial dilutions were plated in duplicate on XLT-4 (xylose lysine tergitol-4) agar. Four serotypes showed an impaired ability to decarboxylate lysine on XLT-4. This inability to decarboxylate lysine was dependent on isolate, stress status, and incubation time. When the isolates’ ability to decarboxylate lysine was examined using biochemical tests, cultures were found to be able to decarboxylate lysine with the exception of S. Infantis. This suggests that XLT-4 contains a biochemical stressor(s) which affects the rate of decarboxylation by these Salmonella. These results suggest that acidic conditions may influence the detection and confirmation of Salmonella in feed. 相似文献
85.
Incorporating green and sustainable remediation analysis in coal combustion residuals (CCR) surface impoundment closure decision making
下载免费PDF全文
![点击此处可从《补救:环境净化治理成本、技术与工艺杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In response to new coal combustion residuals (CCR) disposal regulations, many coal‐fired utilities have closed existing unlined surface impoundments (SIs) that were traditionally used for disposal of CCR. The two primary closure options are closure‐in‐place (CIP), which involves dewatering and capping, and closure‐by‐removal (CBR), which includes excavation, transportation, and disposal of the CCR into a lined landfill. This article provides a methodology and a case study of how green and sustainable remediation concepts, including accounting for the life cycle environmental footprints and the physical risks to workers and community members, can be incorporated into the closure decision‐making process. The environmental impacts, occupational risks, and traffic‐related fatalities and injuries to workers and community members were calculated and compared for closure alternatives at a hypothetical site. The results demonstrated that the adverse impacts of the CBR option were significantly greater than those of the CIP option with respect to the analyzed impact pathways. 相似文献
86.
Sites with dense nonaqueous‐phase liquid (DNAPL) contamination present significant remediation challenges in terms of technical practicability and cost. Remedial approaches to DNAPL sites often follow a management approach rather than removal or eradication approaches, particularly due to the uncertainties associated with the benefits of partial source mass removal, as complete source removal is unlikely. Mass‐removal technologies should be evaluated for all DNAPL sites, although implementation of recovery technologies will be limited to a few sites based upon site‐specific factors. Sitewide remedial strategies that employ source reduction, where applicable, and incorporate associated risk‐reduction technologies, including monitored natural attenuation, are advised. Creosote DNAPL sites are particularly challenging, as they are predominantly composed of low‐solubility polycyclic aromatic hydrocarbons that form long‐term continuing sources. Additionally, the physical properties of creosote DNAPL, including high viscosity and relatively low density, result in significant migration potential and considerable dissolved‐phase groundwater impacts. An innovative creosote DNAPL source recovery well design was developed to achieve separate‐phase removal of pooled creosote DNAPL. The design presented herein employs modified circulation‐well technology to mobilize DNAPL to the engineered recovery well, where it is gravity‐settled into a sump to permit separate‐phase mass removal of the emplaced DNAPL source without groundwater production or treatment. A discharge mass flux protocol was developed to verify dissolved‐phase plume stability and the benefit of the source mass removal. © 2013 Wiley Periodicals, Inc. 相似文献
87.
Bellmore JR Baxter CV Ray AM Denny L Tardy K Galloway E 《Environmental management》2012,49(3):734-750
Pre-restoration studies typically focus on physical habitat, rather than the food-base that supports aquatic species. However,
both food and habitat are necessary to support the species that habitat restoration is frequently aimed at recovering. Here
we evaluate if and how the productivity of the food-base that supports fish production is impaired in a dredge-mined floodplain
within the Yankee Fork Salmon River (YFSR), Idaho (USA); a site where past restoration has occurred and where more has been
proposed to help recover anadromous salmonids. Utilizing an ecosystem approach, we found that the dredged segment had comparable
terrestrial leaf and invertebrate inputs, aquatic primary producer biomass, and production of aquatic invertebrates relative
to five reference floodplains. Thus, the food-base in the dredged segment did not necessarily appear impaired. On the other
hand, we observed that off-channel aquatic habitats were frequently important to productivity in reference floodplains, and
the connection of these habitats in the dredged segment via previous restoration increased invertebrate productivity by 58%.
However, using a simple bioenergetic model, we estimated that the invertebrate food-base was at least 4× larger than present
demand for food by fish in dredged and reference segments. In the context of salmon recovery efforts, this observation questions
whether additional food-base productivity provided by further habitat restoration would be warranted in the YFSR. Together,
our findings highlight the importance of studies that assess the aquatic food-base, and emphasize the need for more robust
ecosystem models that evaluate factors potentially limiting fish populations that are the target of restoration. 相似文献
88.
89.
Detecting Temporal Change in Watershed Nutrient Yields 总被引:2,自引:1,他引:1
Meta-analyses reveal that nutrient yields tend to be higher for watersheds dominated by anthropogenic uses (e.g., urban, agriculture) and lower for watersheds dominated by natural vegetation. One implication of this pattern is that loss of natural vegetation will produce increases in watershed nutrient yields. Yet, the same meta-analyses also reveal that, absent land-cover change, watershed nutrient yields vary from one year to the next due to many exogenous factors. The interacting effects of land cover and exogenous factors suggest nutrient yields should be treated as distributions, and the effect of land-cover change should be examined by looking for significant changes in the distributions. We compiled nutrient yield distributions from published data. The published data included watersheds with homogeneous land cover that typically reported two or more years of annual nutrient yields for the same watershed. These data were used to construct statistical models, and the models were used to estimate changes in the nutrient yield distributions as a result of land-cover change. Land-cover changes were derived from the National Land Cover Database (NLCD). Total nitrogen (TN) yield distributions increased significantly for 35 of 1550 watersheds and decreased significantly for 51. Total phosphorus (TP) yield distributions increased significantly for 142 watersheds and decreased significantly for 17. The amount of land-cover change required to produce significant shifts in nutrient yield distributions was not constant. Small land-cover changes led to significant shifts in nutrient yield distributions when watersheds were dominated by natural vegetation, whereas much larger land-cover changes were needed to produce significant shifts when watersheds were dominated by urban or agriculture. We discuss our results in the context of the Clean Water Act. 相似文献
90.