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   602篇
  免费   10篇
电工技术   1篇
化学工业   47篇
金属工艺   4篇
机械仪表   21篇
建筑科学   13篇
矿业工程   2篇
能源动力   12篇
轻工业   187篇
水利工程   8篇
石油天然气   1篇
无线电   23篇
一般工业技术   49篇
冶金工业   179篇
原子能技术   8篇
自动化技术   57篇
  2024年   2篇
  2023年   2篇
  2022年   3篇
  2021年   9篇
  2019年   11篇
  2018年   13篇
  2017年   12篇
  2016年   6篇
  2015年   9篇
  2014年   12篇
  2013年   29篇
  2012年   22篇
  2011年   22篇
  2010年   14篇
  2009年   18篇
  2008年   21篇
  2007年   31篇
  2006年   13篇
  2005年   22篇
  2004年   16篇
  2003年   21篇
  2002年   13篇
  2001年   10篇
  2000年   12篇
  1999年   11篇
  1998年   38篇
  1997年   23篇
  1996年   39篇
  1995年   14篇
  1994年   16篇
  1993年   16篇
  1992年   14篇
  1991年   8篇
  1990年   11篇
  1989年   6篇
  1988年   6篇
  1987年   3篇
  1986年   10篇
  1985年   7篇
  1984年   4篇
  1983年   5篇
  1982年   2篇
  1981年   4篇
  1979年   2篇
  1978年   3篇
  1977年   7篇
  1976年   6篇
  1975年   2篇
  1972年   4篇
  1956年   1篇
排序方式: 共有612条查询结果,搜索用时 15 毫秒
41.
When a disaster occurs, timely actions in response to urgent requests conveyed by critical messages (known as alerts) constitute a vital key to effectiveness. These actions include notifying potentially affected parties so that they can take precautionary measures, gathering additional information, and requesting remedial actions and resource allocation. However, there are different types of disasters such as epidemic outbreaks, natural disasters, major accidents, and terrorist attacks. At the same time, there are also many different parties involved such as governments, healthcare institutions, businesses, and individuals. To address these problems, we introduce a Disaster Notification and Resource Allocation System (DNRAS) based on an Alert Management System (AMS) implemented through Web services. This unified platform supports timely interactions among various parties, focusing on notification and monitoring, resource enquiry and allocation, as well as the mobility of information. We detail the mechanisms of these functions in our system, illustrating the Web services interface parameters for communications and interoperability. We illustrate the applicability of our approach with an example of an epidemic outbreak and discuss the advantage of our approach with respect to various stakeholders of our system.  相似文献   
42.
Opioids are the most effective compounds available for the relief of pain, yet there are a number of side effects that are of great concern to clinicians. For example, opioids are powerful reinforcers, and the treatment of pain using opioids could lead to the development of addiction. In addition, there is an increasing body of literature demonstrating that the repeated administration of opioids could lead to a phenomenon called opioid-induced hyperalgesia (i.e., increased sensitivity to painful stimulation). Studies examining these potential adverse effects are necessary in the development of novel analgesics. Furthermore, most studies of pain sensitivity and pain relief use reflex-based procedures to identify analgesics; however, it is argued here that operant-based procedures provide measures that are more analogous to the human condition (i.e., the mechanisms of pain are similar to those in humans) and should be useful in the assessment of novel analgesics. A series of studies examining the effects of opioids and the influence of variables such as age are discussed to demonstrate the utility of this approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
43.
44.
M.A. Drake    X.Q. Chen    S. Tamarapu    B. Leenanon 《Journal of food science》2000,65(7):1244-1247
ABSTRACT: Chemical, microbiological, and sensory properties for low fat yogurts fortified with 0,1, 2.5, or 5% soy protein concentrate were determined through 1 mo storage at 5 °C. Yogurts were adjusted to equivalent total solids with nonfat dried milk. Microbiological counts, fermentation time, and final developed acidity were not affected by soy protein. Instrumental viscosity and sensory thickness, soy aroma, and soy flavor increased with soy protein addition (P 0.05). Soy flavor and aroma did not increase with storage time. Yogurt with 5% soy protein was darker, more chalky, and less sweet compared to control yogurt or yogurts with lower concentrations of soy protein (P 0.05). Yogurts with 1 or 2.5% soy protein were most similar to control yogurt.  相似文献   
45.
46.
In this paper, system network planning expansion is formulated for mixed integer programming, a genetic algorithm (GA) and tabu search (TS). Compared with other optimization methods, GAs are suitable for traversing large search spaces, since they can do this relatively rapidly and because the use of mutation diverts the method away from local minima, which will tend to become more common as the search space increases in size. GA’s give an excellent trade off between solution quality and computing time and flexibility for taking into account specific constraints in real situations. TS has emerged as a new, highly efficient, search paradigm for finding quality solutions to combinatorial problems. It is characterized by gathering knowledge during the search and subsequently profiting from this knowledge. The attractiveness of the technique comes from its ability to escape local optimality. The cost function of this problem consists of the capital investment cost in discrete form, the cost of transmission losses and the power generation costs. The DC load flow equations for the network are embedded in the constraints of the mathematical model to avoid sub-optimal solutions that can arise if the enforcement of such constraints is done in an indirect way. The solution of the model gives the best line additions and also provides information regarding the optimal generation at each generation point. This method of solution is demonstrated on the expansion of a 10 bus bar system to 18 bus bars. Finally, a steady-state genetic algorithm is employed rather than generational replacement, also uniform crossover is used.  相似文献   
47.
48.
49.
A quasi-analytical method for computing the quasi-static-TEM parameters of the generalized coplanar waveguide (GCPW) is reported. The structure is assumed to be enclosed in a rectangular frame and embedded in a layered medium. Essentially, the method is an analytically enhanced spectral domain formulation. Its application leads to virtually exact results in very short CPU times, making it suitable for CAD purposes. Although the method is somewhat more time consuming than conformal mapping approaches, it is a useful alternative because of its exactness and ability to deal with multilayer structures. © 1994 John Wiley & Sons, Inc.  相似文献   
50.
Our objective was to measure whey protein removal percentage from separated sweet whey using spiral-wound (SW) polymeric microfiltration (MF) membranes using a 3-stage, 3× process at 50°C and to compare the performance of polymeric membranes with ceramic membranes. Pasteurized, separated Cheddar cheese whey (1,080 kg) was microfiltered using a polymeric 0.3-μm polyvinylidene (PVDF) fluoride SW membrane and a 3×, 3-stage MF process. Cheese making and whey processing were replicated 3 times. There was no detectable level of lactoferrin and no intact α- or β-casein detected in the MF permeate from the 0.3-μm SW PVDF membranes used in this study. We found BSA and IgG in both the retentate and permeate. The β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) partitioned between retentate and permeate, but β-LG passage through the membrane was retarded more than α-LA because the ratio of β-LG to α-LA was higher in the MF retentate than either in the sweet whey feed or the MF permeate. About 69% of the crude protein present in the pasteurized separated sweet whey was removed using a 3×, 3-stage, 0.3-μm SW PVDF MF process at 50°C compared with 0.1-μm ceramic graded permeability MF that removed about 85% of crude protein from sweet whey. The polymeric SW membranes used in this study achieve approximately 20% lower yield of whey protein isolate (WPI) and a 50% higher yield of whey protein phospholipid concentrate (WPPC) under the same MF processing conditions as ceramic MF membranes used in the comparison study. Total gross revenue from the sale of WPI plus WPPC produced with polymeric versus ceramic membranes is influenced by both the absolute market price for each product and the ratio of market price of these 2 products. The combination of the market price of WPPC versus WPI and the influence of difference in yield of WPPC and WPI produced with polymeric versus ceramic membranes yielded a price ratio of WPPC versus WPI of 0.556 as the cross over point that determined which membrane type achieves higher total gross revenue return from production of these 2 products from separated sweet whey. A complete economic engineering study comparison of the WPI and WPPC manufacturing costs for polymeric versus ceramic MF membranes is needed to determine the effect of membrane material selection on long-term processing costs, which will affect net revenue and profit when the same quantity of sweet whey is processed under various market price conditions.  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