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91.
High-accuracy surface modelling and its application to DEM generation   总被引:1,自引:0,他引:1  
An innovative method, high-accuracy surface modelling (HASM), is presented, which is based on the fundamental theorem of surfaces. The fundamental theorem of surfaces makes sure that a surface is uniquely defined by the first and second fundamental coefficients. Numerical tests of a Gaussian synthetic surface show that the Root Mean Square Error of the HASM method is much less than the ones of classical methods, such as the Triangulated Irregular Network, Spline, Inverse Distance Weight and Kriging methods. The HASM method gives a solution to the error problem that has long troubled generations of digital elevation models. All the methods for surface modelling are used to simulate a Digital Elevation Map (DEM) of Qian-Yan-Zhou Experimental Station for Red Soil and Hilly Land, which has a great topographical variety. Shaded relief maps of the simulated DEMs are developed to represent the terrain relief of Qian-Yan-Zhou Experimental Station, which shows that simulation results of the HASM method are much better than the ones of classical methods.  相似文献   
92.
93.
Ethanol production from wheat has become an emerging economic activity in Henan Province due to the establishment in 2001 of the National Program for Alcohol Production. The program aimed at facing the unfolding world energy crisis in the near future and increasing China's energy security. Instead, in spite of claims for “green energy”, such an activity is likely to generate great environmental damage and social problems. Moreover, the international market prices for raw materials (especially cereals) and fossil oil are putting this activity under siege. This research presents an energy and eMergy analysis of a typical wheat plantation/alcohol distillery system, in the Henan Province. Comparison is drawn with bioethanol production in Italy, based on corn from intensive, industrialized agriculture. Energy and eMergy indices of ethanol production from wheat and corn in the two agro-industrial systems are respectively as follows: output/input energy ratio, 1.09 (wheat) and 1.19 (corn); transformity of bioethanol, 2.77×105 and 1.89×105 seJ/J; renewability, 20% and 11%; eMergy yield ratio, 1.24 and 1.14; environmental loading ratio, 4.05 and 7.84; and finally eMergy sustainability index, 0.31 and 0.15. Results show that bioethanol from food crops is not a sustainable source of fuel.  相似文献   
94.
A survey of selected heavy metal concentrations in Wisconsin dairy feeds   总被引:1,自引:0,他引:1  
Heavy metals such as zinc (Zn), copper (Cu), chromium (Cr), arsenic (As), cadmium (Cd), and lead (Pb) are potential bioaccumulative toxins of the dairy production system. The heavy metal content of dairy feeds, however, remains poorly documented, particularly in the United States. This survey determined the heavy metal content of 203 typical dairy ration components sampled from 54 dairy farms in Wisconsin. Lowest heavy metal concentrations were found in homegrown alfalfa (Medicago sativa L.) hay and haylage, and corn (Zea mays L.) grain and silage. Highest metal concentrations were found in purchased feeds, particularly mineral supplements, and to a lesser extent corn- or soybean-based concentrates. Zinc and Cu were found at the highest concentration in complete dairy (total mixed and aggregated component) rations and reflected the deliberate addition of these metals to meet animal nutrient requirements although more than half the farms fed Cu and Zn above US recommended levels. Concentrations of Cr, As, Cd, and Pb were present in much lower concentrations and decreased in the order Cr > As > Pb > Cd. No complete Wisconsin dairy ration contained heavy metal concentrations above US maximum acceptable concentrations and would be unlikely to induce any toxic effects in dairy cattle. Concentrations of Cd in complete dairy rations were closest to US maximum acceptable concentrations, suggesting the greatest potential long-term risk to exceed US maximum acceptable concentrations if whole farm levels of Cd were to increase in the future. With the exception of Pb, the main sources of Zn, Cu, Cr, As, and Cd in the complete dairy feed ration originated from imported feed. The continued importation of heavy metals in dairy feed is likely to be associated with accumulation of these metals in soils where manure is applied. Although the cycling of many heavy metals through the dairy food chain will be limited by factors such as a soil's cation exchange capacity, pH, salinity, and phytotoxicity of the metal, these may be less limiting for Cd. It is important that sources of Cd in the dairy system are identified and minimized to prevent problems associated with Cd accumulation in the dairy soil system arising over the long-term.  相似文献   
95.
《Journal of power sources》2001,96(1):246-251
This paper summarizes and updates the findings of the North American technology and industrial base organization (NATIBO) study entitled “Rechargeable Battery/Systems for Communication/Electronic Application”. The mission of the NATIBO organization is to promote a cost effective and healthy technology and industrial base that is responsive to the national and economical security needs of the United States and Canada.  相似文献   
96.
Emergy Accounting and Synthesis, developed by Howard Odum in the 1980s, accounts for both the work of nature and that of humans as part of it in generating products and services. Since the 1990s, when Odum's system theories and emergy approach were introduced to China, a great attention was paid to them, since they appeared to Chinese scholars very important, comprehensive, and rich with application opportunities to China's economic development and environmental management. Until now more than 150 papers related to emergy theories were published in Chinese scientific journals, more than 20 dissertations presented in all Chinese Universities, and a large number of emergy-based papers were authored by Chinese scholars in international journals. Also, several reports dealing with emergy evaluation of different provinces of China were presented to local governments for decision-making. Emergy theories were applied to valuation of ecosystems and eco-industrial parks, as well as to studies of benefits/cost analysis and feasibility of ecological engineering. Meanwhile, a series of monographs and translated books related to emergy theories were published in China, some of which are used as text books in Chinese universities and institutes.  相似文献   
97.
Crop models must be improved to account for the effects of heat stress events on crop yields. To date, most approaches in crop models use air temperature to define heat stress intensity as the cumulative sum of thermal times (TT) above a high temperature threshold during a sensitive period for yield formation. However, observational evidence indicates that crop canopy temperature better explains yield reductions associated with high temperature events than air temperature does. This study presents a canopy level energy balance using Monin–Obukhov Similarity Theory (MOST) with simplifications about the canopy resistance that render it suitable for application in crop models and other models of the plant environment. The model is evaluated for a uniform irrigated wheat canopy in Arizona and rainfed maize in Burkina Faso. No single variable regression relationships for key explanatory variables were found that were consistent across sowing dates to explain the deviation of canopy temperature from air temperature. Finally, thermal times determined with simulated canopy temperatures were able to reproduce thermal times calculated with observed canopy temperature, whereas those determined with air temperatures were not.  相似文献   
98.
Rust belt cities are a special but important phenomenon in the world's industrialization landscape and city development trajectory. This profile analyses the struggling process and revitalization initiatives of Harbin, which was the first city established after the liberation of China, featuring the largest land area and highest latitude among all Chinese cities. The remarkable history of urban and industrial development once made Harbin the cradle of manufacturing in China, strongly supported by national government with concentration of SOEs. The city however has been suffering during the transition to a market economy. Its transition is painfully challenged by the strong socialist legacies of SOEs. This paper emphasizes that the new initiatives of Harbin, based on local endowments, cold climate condition and geolocation, demonstrate great potential for successful revitalization. Such strategic choices provide experiences and alternatives for other rust belt cities.  相似文献   
99.
Virtual water has become an important part of global water supply and demand and has led to the globalization of water. Virtual water research most mainly focused on the field of agriculture. Minimal attention has been devoted to forest virtual water (FVW). To our knowledge, no research on the monitoring and analysis of FVW through remote-sensing technology has been conducted. In this study, based on object-oriented technology and through the use of 30 scenes from multi-temporal Chinese HJ-CCD images, we monitored FVW in Hunan Province, China, in 2010 and analysed the pattern of FVW. Results showed that the amount of FVW is large and greater than that of entity water. Hunan Province had 5.83 × 1011m3 FVW in 2010, which was 3.09 times the amount of agriculture and livestock. FVW was thrice as large as the total entity water, 4.07 times the amount of surface water, and 14.57 times the amount of underground water in Hunan Province. The distribution of FVW in Hunan Province is uneven and presents a trend that gradually increases from northeast to southwest; nevertheless, the trend is reasonable and in favour of alleviating and optimizing the pattern of water resources. Our analysis indicated that we need to improve the cognition of virtual water and pay due attention to FVW from the perspective of water management and allocation. Our results also indicated that forest and woody products are water intensive. An efficient method of balancing FVW and other uses of water is thus required; control and management of water consumption in forests should also be implemented under the condition of protecting the environment. For China, woody forest products should be mainly imported to improve water-use efficiency and relieve the shortage of water. Meanwhile, remote-sensing technology is a useful tool, and Chinese HJ-CCD images are an important data source for the estimation of FVW.  相似文献   
100.
Many developing countries grapple with the problem of rapid informal settlement emergence and expansion. This exacts considerable costs from neighbouring urban areas, largely as a result of environmental, sustainability and health-related problems associated with such settlements, which can threaten the local economy. Hence, there is a need to understand the nature of, and to be able to predict, future informal settlement emergence locations as well as the rate and extent of such settlement expansion in developing countries.A novel generic framework is proposed in this paper for machine learning-inspired prediction of future spatio-temporal informal settlement population growth. This data-driven framework comprises three functional components which facilitate informal settlement emergence and growth modelling within an area under investigation. The framework outputs are based on a computed set of influential spatial feature predictors pertaining to the area in question. The objective of the framework is ultimately to identify those spatial and other factors that influence the location, formation and growth rate of an informal settlement most significantly, by applying a machine learning modelling approach to multiple data sets related to the households and spatial attributes associated with informal settlements. Based on the aforementioned influential spatial features, a cellular automaton transition rule is developed, enabling the spatio-temporal modelling of the rate and extent of future formations and expansions of informal settlements.  相似文献   
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