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341.
GIS与运输经济统计结合可进行运量模拟、分析、预测和规划。实验表明三峡建坝断航对全国交通流格局影响是局域性的,但对川,鄂,苏,沪区际交流影响较大,华南三港因接受出川转运物资吞吐量将增加2% ̄7%,襄渝货运量增加600万t,川黔-黔桂线运量将增加100万t。 相似文献
342.
In addition to heat production on the comb surface, honeybee workers frequently visit open cells (“gaps”) that are scattered
throughout the sealed brood area, and enter them to incubate adjacent brood cells. We examined the efficiency of this heating
strategy under different environmental conditions and for gap proportions from 0 to 50%. For gap proportions from 4 to 10%,
which are common to healthy colonies, we find a significant reduction in the incubation time per brood cell to maintain the
correct temperature. The savings make up 18 to 37% of the time, which would be required for this task in completely sealed
brood areas without any gaps. For unnatural high proportions of gaps (>20%), which may be the result of inbreeding or indicate
a poor condition of the colony, brood nest thermoregulation becomes less efficient, and the incubation time per brood cell
has to increase to maintain breeding temperature. Although the presence of gaps is not essential to maintain an optimal brood
nest temperature, a small number of gaps make heating more economical by reducing the time and energy that must be spent on
this vital task. As the benefit depends on the availability, spatial distribution and usage of gaps by the bees, further studies
need to show the extent to which these results apply to real colonies.
M. Fehler and M. Kleinhenz contributed equally to this work. 相似文献
343.
Jürgen Bennewitz 《Environment, Development and Sustainability》2009,11(1):127-136
The IPCC Working Groups I–III 2007 publications does not consider the question of the influence of the entropy increase in
the atmosphere on current climate development. An investigation into this question, both in general terms as well as by two
quantitative approaches, reveals we must consider the entropy produced by man in connection with climate development, especially
with regard to the temperature increase of the atmosphere. The IPCC report also fails to mention the production of CO2 by humans and livestock, but calculations show we must also consider such greenhouse gas CO2 production. For solving the mitigating processes, we therefore have to take into account both the human induced entropy production
and the direct human and livestock CO2 output. In consideration of these findings, it seems necessary to introduce an “entropy identity” to people who wish to be
able to continue to live on the planet. The introduction of an entropy tax might also help in solving the most urgent fundamental
problem humanity has ever had to face.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
344.
根据FHD 1型质子磁力仪在实际使用过程中存在的一些问题 ,以及一些用户提出的建议和要求 ,对FHD 1型质子磁力仪的实时时钟、标定方法、通用性与适应性、抗干扰能力方面进行了改进和完善 ,本文对此作介绍。 相似文献
345.
Scenario study for a regional low-carbon society 总被引:1,自引:0,他引:1
Japan should undertake drastic greenhouse gas (GHG) emission reductions by the middle of this century in order to mitigate
climate change problems. Municipalities should design and execute scenarios toward a low-carbon society suited to their respective
regions. This study describes long-term future visions developed for Shiga Prefecture targeting CO2 emission reductions of 30–50% by 2030, and presents scenarios to attain these targets, which are achievable with mild economic
growth. For targets over a 30% reduction, region-specific measures including land-use reform and citizen behavioral changes
are necessary. Compared with other regions in Japan, Shiga should give priority to a modal shift in transport, efficiency
improvements in industry, and photovoltaic energy generation. 相似文献
346.
147团场自建场以来,在经济发展中取得了巨大成就,但同时必须看到自然对发展的限制与惩罚。从环境学出发,作者对该场的经济与环境发展规划进行了讨论,分析了农业生态环境的有利和不利条件,提出了发展经济与合理利用环境资源的建议。 相似文献
347.
Lynn E. Johnson 《Journal of the American Water Resources Association》1990,26(2):299-311
ABSTRACT: Computer-aided planning (CAP) for multiple-purpose reservoir operations involves use of state-of-the-art simulation and optimization methods, color graphic displays, and interactive computing interfaces. These technologies were integrated into a coherent system that has user-friendly interfaces to help the process of communicating reservoir system operations, solicit planning participant preferences and valuation judgments, and provide understandable feedback of system performance. The CAP system was imbedded in a comprehensive public involvement program that paralleled the reservoir operating policy modeling process, as part of multipurpose reservoir operations planning on the Great Plains Reservoirs in Colorado. Experience with the approach indicates the involved publics can quickly learn of reservoir system limitations and opportunities, and can indeed participate in the operations planning process. 相似文献
348.
W. F. Calhoun E. F. Benfield D. N. Contractor 《Journal of the American Water Resources Association》1980,16(1):63-68
ABSTRACT: A combination pumped storage reservoir system was simulated by modifying the WRE deep reservoir model. Each of the two reservoirs was described by a copy of the WRE model program, the two programs were converted into subroutines and were called upon alternately by a main program. Operationally, the contributing reservoir, i.e., the reservoir from which flow was discharged, was simulated for one execution interval (1 hour), followed by simulating the receiving reservoir for the same execution interval. The main program directed the discharge temperature of the contributing reservoir for each execution interval as input for simulating the receiving reservoir. The two subroutines were run in this interactive mode for a simulation period of one year. Two simulations, labeled “Pump” and “Net,” were effected and differed basically in the distribution of flow volumes exchanged between the reservoirs. In the ‘Pump’ simulation the total hourly flow volumes were distributed into appropriate horizontal layers of the lakes as determined by temperature-density relationships, i.e., the pumped discharges were distributed into the upper lake and the generation discharges were distributed into the lower lake. In the ‘Net’ simulation only the net daily discharges (daily difference between pump-back and generation at the upper dam), distributed uniformly over 24 hours, were mixed into the horizontal layers of the two lakes. Both simulations produced annual thermal regimes that were apparently within reason for the geographical area and the nature of the input data. However, neither accurately reflected a generalized conditions for the reservoirs because the Pump simulation reflected conditions in the forebay and tailrace of the Upper dam while the Net simulation reflected conditions of the remaining parts of the reservoirs. 相似文献
349.
350.
为了强化海洋油气项目集的风险管理,以海洋油气田固定区块开发为范围,基于甲方油气田单位和乙方服务单位立场,对项目集进行全生命周期的风险管理;将海洋油气项目集生命周期划分为6个阶段;提出了滚动风险管理模式,给出各阶段风险分解结构和风险应对策略;以时间、成本、质量为控制要素,建立项目整体风险动态评估方法。研究结果表明:通过生命周期6个阶段和整体2级动态迭代风险控制,能更早发现项目集各级过程风险,有助于避免或降低风险事故带来的损失,更有效地保障项目集收益和组织战略实现,可为我国海上油气田开发风险管理提供新参考。 相似文献