首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   53篇
  免费   0篇
  国内免费   1篇
安全科学   1篇
废物处理   5篇
环保管理   4篇
综合类   8篇
基础理论   3篇
污染及防治   26篇
评价与监测   3篇
社会与环境   4篇
  2018年   2篇
  2017年   2篇
  2014年   1篇
  2013年   7篇
  2012年   3篇
  2011年   4篇
  2010年   2篇
  2008年   3篇
  2007年   4篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  2003年   2篇
  2002年   5篇
  2001年   3篇
  1994年   2篇
  1987年   1篇
  1982年   2篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有54条查询结果,搜索用时 15 毫秒
21.
22.
Chlorinated, nitrated, carboxylated or methylated benzenes, phenols and anilines reacted with chloramine to give cyanogen chloride, independently of the positions and the numbers of the substituents. Among these compounds, 2,4,6-trichlorophenol afforded cyanogen chloride in a relatively high yield of 13.3%, and the intermediates in the reaction were 2,6-dichloro-1,4-benzoquinone-4-(N-chloro)imine and 4,6-dichloro-1,2-benzoquinone-2-(N-chloro)-imine, of which the latter was the main intermediate.  相似文献   
23.
To confirm whether the amplitude of diel temperature cycles causes a phase shift of adult eclosion rhythm of the onion fly, Delia antiqua, the peak time (Ø E) of adult eclosion was determined under various thermoperiods with a fixed temperature either in the warm or cool phase and temperature differences ranging from 1°C to 4°C between the two phases. Irrespective of the temperature level during the warm or cool phase, Ø E occurred earlier with decreasing amplitude of the temperature cycle. The results strongly support the previous conclusion of Tanaka and Watari (Naturwissenschaften 90:76–79, 2003) that D. antiqua responds to the amplitude of temperature cycle as a cue for the circadian adult eclosion timing. The phase advance was larger in thermoperiods with a fixed warm-phase temperature than in those with a fixed cool-phase temperature. This might be ascribed to the interaction between the amplitude and level of temperature in the thermoperiodic regimes.  相似文献   
24.
This paper extrapolates future paths of genuine savings (GS) by using our integrated assessment model. The results with the base case (BC) indicate that both GS without population change (GS) and GS with population change (GSn) are almost positive in OECD countries in the twenty-first century (satisfying the necessary but insufficient condition for sustainability); those numbers are projected to be negative in 2100. Asia (ASIA), the Middle East and Africa (MEAF), the former Soviet Union and Eastern Europe (FSEE), and the world show upward trends for both values, showing negative signs in 2010 and positive signs after 2050 (in ASIA, MEAF, and the world) and in 2100 (in FSEE). The values in Latin America (LAMR) remain negative throughout. We examine additional following three cases: demand reduction (DR), carbon dioxide (CO2) emissions reduction (CR), and population reduction (PR). The GSn results compared to the BC indicate that (1) GSn in DR is similar to that of BC, (2) GSn in PR is slightly higher than that of BC, and (3) GSn in CR is unexpectedly lower than that of BC. This GSn reduction in the CR case derives from the fact that the term for calculating resource depletion (especially resource rent, which equals the difference between price and cost) in GS and GSn increased, leading to a greater term being subtracted from gross savings. The resource price increases with the marginal price of natural gas, given the energy-source shift in reducing CO2 emissions, from cheap coal to expensive natural gas.  相似文献   
25.
The tropical deciduous forest in Bangladesh provides a substantial part of country’s forest and where the government has introduced participatory agroforestry landuse. This study examined management issues, financial viability, and environmental as well as social sustainability of this landuse system. The forest department allocated a plot of size 1.0 ha among the selected participants where they were allowed to practice agriculture as well as to plant tree species for 10 years. The financial indicators indicated that the landuse system was profitable and attractive [net present value (NPV) = US$ 17,710 and benefit-cost ratio (BCR) = 4.12]. It was also viable and suitable from the social and environmental stand points. The study concluded that under the present environmental and socio-economic scenario, this production system could be the best management tool that would earn money, stop forest degradation, and finally be a model of sustainable land management in an overpopulated country.  相似文献   
26.
The utilization of bioethanol is being focused on as a fuel alternative to oil and or natural gas. Bioethanol production from cellulosic plant residues is one of the solutions proposed for the problems caused by usage of food crops that are also vital for human consumption, such as sugar cane and corn, as a source of bioethanol. However, to utilize these new sources for bioethanol production, conditions for saccharification in each different material have not been optimized. In this study, we reported some optimum conditions for the saccharification of Korean lawn grass (KL) and bent grass (BG) using acremonium cellulase and endoglucanase as saccharifying enzymes for ethanol fermentation. With respect to saccharification of KL and BG, 0.19 and 0.18 g of d-glucose per g-substrate at maximum were produced, respectively. Comminution with a ball mill was found to be effective in the saccharification of KL, while ball-milled BG showed no significant improvement in saccharification. Being incorporated with 99 % of d-glucose consumption, saccharified KL was incubated for 3 days with Saccharomyces cerevisiae and Zymomonas mobilis, respectively, and each mixture fermented to ethanol yielding approximately 100 % of theoretical values from d-glucose consumption, respectively.  相似文献   
27.
We investigated the biodegradation of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and 2,4-dinitrophenol (2,4-DNP) in the rhizosphere of Spirodela polyrrhiza plants by conducting degradation experiments with three river water samples supplemented with each nitrophenol (NP). We then isolated NP-degrading bacteria both from the S. polyrrhiza roots and from the river water. In the river water samples, removal of the three NP was accelerated in the presence of S. polyrrhiza plants. The three NPs persisted in an autoclaved solution with sterile plants suggests that NP removal was accelerated largely by bacterial NP biodegradation rather than by adsorption and uptake by the plants. We isolated 8 strains of NP-degrading bacteria: 6 strains from the S. polyrrhiza roots and 2 strains from river water without the plants. The 2-NP- and 2,4-DNP-degrading bacteria were isolated only from the S. polyrrhiza roots. The 4-NPdegrading bacteria different from those isolated from the river water samples were also found on S. polyrrhiza roots. The 2-NP- and 4-NP-degrading strains isolated from the roots utilized the corresponding NP (0.5 mmol/L) as the sole carbon and energy source. The 2,4-DNP-degrading strains isolated from the roots showed substantial 2,4-DNP-degrading activity, but the presence of other carbon and energy sources was required for their growth. The isolated NP-degrading bacteria from the roots must have contributed to the accelerated degradation of the three NPs in the rhizosphere of S. polyrrhiza. Our results suggested that rhizoremediation with S. polyrrhiza may be effective for NP-contaminated surface water.  相似文献   
28.
The influence of prey animals on the supercooling ability of the house spider, Achaearanea tepidariorum, was studied by feeding spiders with field-collected and laboratory-cultured prey animals. Irrespective of the prey species supplied, spiders given field-collected prey had a higher supercooling point than those given laboratory-cultured counterparts. This means that (1) the field prey animals contained some efficient ice nucleators, whereas the laboratory animals were free from such substances and (2) the ice nucleators must be of external origin. Several lines of evidence also suggest that, under natural conditions, potential prey animals for the house spider are highly contaminated with ice nucleators.  相似文献   
29.
Total diet study (TDS) samples of 14 food groups from 16 locations in Japan, collected in 1999 and 2000, were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) to estimate the update of daily intake of these contaminants from food. The mean daily intake of toxic equivalency (TEQ) for an adult weighing 50 kg, calculated at non-detected isomer concentrations equal to zero (ND=0), was estimated to be 2.25 pg TEQ/kg b.w./day. When non-detected isomer concentrations are assumed to be equal to half of the limits of detection (ND=1/2 LOD), the mean daily intake was estimated to be 3.22 pg TEQ/kg b.w./day. These values were below the tolerable daily intake (TDI) of 4 pg TEQ/kg b.w. for PCDD/Fs and dioxin-like PCBs set in Japan. In both the estimates, the mean daily intakes were highest from fish and shellfish (76.9% at ND=0 and 53.9% at ND=1/2 LOD of the total TEQs), followed by those from meat and eggs (15.5% at ND=0 and 11.7% at ND=1/2 LOD of the total TEQs). Congener specific data revealed that these total TEQ levels were dominated by 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 3,3,4,4,5-PeCB in each case (71.7% at ND=0 and 63.1% at ND=1/2 LOD of the total TEQs). The dioxin-like PCBs (non-ortho and mono-ortho PCBs) accounted for about 50% of these total TEQs. These data will be very useful in the risk assessment of PCDD/Fs and dioxin-like PCBs from food in Japan.  相似文献   
30.
Overview   总被引:2,自引:0,他引:2  
  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号