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   128篇
  免费   8篇
电工技术   1篇
化学工业   31篇
金属工艺   4篇
建筑科学   9篇
能源动力   3篇
轻工业   12篇
石油天然气   1篇
无线电   4篇
一般工业技术   20篇
冶金工业   34篇
自动化技术   17篇
  2024年   2篇
  2022年   7篇
  2021年   8篇
  2020年   3篇
  2019年   2篇
  2018年   1篇
  2017年   6篇
  2016年   5篇
  2015年   4篇
  2014年   3篇
  2013年   12篇
  2012年   6篇
  2011年   6篇
  2010年   7篇
  2009年   4篇
  2008年   1篇
  2007年   3篇
  2006年   3篇
  2005年   2篇
  2004年   1篇
  2003年   1篇
  2002年   2篇
  1999年   1篇
  1998年   4篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1993年   2篇
  1992年   1篇
  1989年   3篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1983年   5篇
  1982年   4篇
  1981年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   3篇
  1975年   4篇
  1973年   1篇
  1972年   2篇
  1970年   1篇
  1954年   1篇
排序方式: 共有136条查询结果,搜索用时 0 毫秒
121.
122.
Hypertext systems allow flexible access to topics of information, but this flexibility has disadvantages. Users often become lost or overwhelmed by choices. An adaptive hypertext system can overcome these disadvantages by recommending information to users based on their specific information needs and preferences. Simple associative matrices provide an effective way of capturing these user preferences. Because the matrices are easily updated, they support the kind of dynamic learning required in an adaptive system.HYPERFLEX, a prototype of an adaptive hypertext system that learns, is described. Informal studies with HYPERFLEX clarify the circumstances under which adaptive systems are likely to be useful, and suggest that HYPERFLEX can reduce time spent searching for information by up to 40%. Moreover, these benefits can be obtained with relatively little effort on the part of hypertext authors or users.The simple models underlying HYPERFLEX's performance may offer a general and useful alternative to more sophisticated modelling techniques. Conditions under which these models, and similar adaptation techniques, might be most useful are discussed.  相似文献   
123.
Recent computational models describing the contribution of the cerebral hemispheres to visual imagery have suggested an exclusive capacity of the left hemisphere to generate multipart images. A brief review of relevant findings indicates that the evidence presented in support of this suggestion is not entirely compelling; this prompted a reexamination of this issue in a lateral tachistoscopic study on normal adults. Sixteen subjects participated in two experiments in which they had to decide whether or not a lowercase letter contained a segment extending above or below the main body of the letter. This decision was made directly on lowercase letters in one experiment (perceptual task) and on their generated images in the other experiment (imagery task). The quality of the letters (clear or blurred) and the retinal eccentricity of stimulus presentation (small or large) were orthogonally manipulated. The perceptual task yielded no main effect of visual field but a significant interaction of visual field and letter quality. By contrast, the imagery task resulted in a left visual-field superiority but no interaction involving the visual fields—a departure from predictions based on current models of visual imagery. In addition, the pattern of results in the imagery task corresponded to that obtained with blurred letters in the perceptual task, suggesting limitations in spatial resolution of visual images. Implications of these results for models of cerebral lateralization and visual imagery are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
124.
Supporting geographically-aware web document foraging and sensemaking   总被引:1,自引:0,他引:1  
This paper reports on the development and application of strategies and tools for geographic information seeking and knowledge building that leverages unstructured text resources found on the web. Geographic knowledge building from unstructured web sources starts with web document foraging during which the quantity, scope and diversity of web-based information create incredible cognitive burdens on an analyst’s or researcher’s ability to judge information relevancy. Determining information relevancy is ultimately a process of sensemaking. In this paper, we present our research on visually supporting web document foraging and sensemaking. In particular, we present the Sense-of-Place (SensePlace) analytic environment. The scientific goal of SensePlace is to visually and computationally support analyst sensemaking with text artifacts that have potential place, time, and thematic relevance to an analytical problem through identification and visual highlighting of named entities (people, places, times, and organizations) in documents, automated inference to determine document relevance using stored knowledge, and a visual interface with coupled geographic map, timeline, and concept graph displays that are used to contextualize the contexts of potentially relevant documents. We present the results of a case study analysis using SensePlace to uncover potential population migration, geopolitical, and other infectious disease dynamics drivers for measles and other epidemics in Niger. Our analysis allowed us to demonstrate how our approach can support analysis of complex situations along (a) multi-scale geographic dimensions (i.e., vaccine coverage areas), (b) temporal dimensions (i.e., seasonal population movement and migrations), and (c) diverse thematic dimensions (effects of political upheaval, food security, transient movement, etc.).  相似文献   
125.
Co‐delivery of both chemotherapy drugs and siRNA from a single delivery vehicle can have a significant impact on cancer therapy due to the potential for overcoming issues such as drug resistance. However, the inherent chemical differences between charged nucleic acids and hydrophobic drugs have hindered entrapment of both components within a single carrier. While poly(ethylene glycol)‐block‐poly(lactic‐co‐glycolic acid) (PEG–PLGA) copolymers have been used successfully for targeted delivery of chemotherapy drugs, loading of DNA or RNA has been poor. It is demonstrated that significant amounts of DNA can be encapsulated within PLGA‐containing nanoparticles through the use of a new synthetic DNA analog, click nucleic acids (CNAs). First, triblock copolymers of PEG‐CNA‐PLGA are synthesized and then formulated into polymer nanoparticles from oil‐in‐water emulsions. The CNA‐containing particles show high encapsulation of DNA complementary to the CNA sequence, whereas PEG‐PLGA alone shows minimal DNA loading, and non‐complementary DNA strands do not get encapsulated within the PEG‐CNA‐PLGA nanoparticles. Furthermore, the dye pyrene can be successfully co‐loaded with DNA and lastly, a complex, larger DNA sequence that contains an overhang complementary to the CNA can also be encapsulated, demonstrating the potential utility of the CNA‐containing particles as carriers for chemotherapy agents and gene silencers.  相似文献   
126.
Heart failure (HF) remains a severe disease with a poor prognosis. HF biomarkers may include demographic features, cardiac imaging, or genetic polymorphisms but this term is commonly applied to circulating serum or plasma analytes. Biomarkers may have at least three clinical uses in the context of HF: diagnosis, risk stratification, and guidance in the selection of therapy. Proteomic studies on HF biomarkers can be designed as case/control using clinical endpoints; alternatively, left ventricular remodeling can be used as a surrogate endpoint. The type of samples (tissue, cells, serum or plasma) used for proteomic analysis is a key factor in the research of biomarkers. Since the final aim is the discovery of circulating biomarkers, and since plasma and serum samples are easily accessible, proteomic analysis is frequently used for blood samples. However, standardization of sampling and access to low-abundance proteins remains problematic. Although, proteomics is playing a major role in the discovery phase of biomarkers, validation in independent populations is necessary by using more specific methods. The knowledge of new HF biomarkers may allow a more personalized medicine in the future.  相似文献   
127.
Urban commercial banks are regional banks which have gained tremendous importance in the last two decades in China. There is, however, a lack of research on regional banking, especially on the Chinese regional banking industry. Therefore, using an innovative spatial approach, this paper investigates the efficiency of 65 Chinese urban commercial banks across 26 regions during 2013–2017. A key finding for our sample is the significant spatial dependence of loans of Chinese urban commercial banks with their neighbouring regions’ banks. Short‐run efficiency is increasing during the research period. For regions with less than three urban commercial banks, the average efficiencies are stable and relatively high. However, regions with more banks have both the highest and lowest efficient banks at the same time. These interesting results fit with the development process of Chinese urban commercial banking, in which the market restructuring has contributed to banks’ efficiency.  相似文献   
128.
A model of the evolution of the onshore wind turbine blade mass installed in Denmark is proposed described by a Weibull distribution, and the age of the blades is estimated from decommissioning data to = 29 years when half of the blade mass of an installation year has been decommissioned. This is considerably longer than the 20 year design lifetime of onshore turbines, which is often assumed to be an estimate of the End-of-Life of turbine blades. Thus, blade waste predictions using the simple assumption may predict that installed blade masses are entering recycling processes about 9 years sooner that what is observed in Denmark. The blade mass for decommissioning in Denmark is estimated to peak at 2000 and 5000 ton/year in 2028 and 2045 using the Weibull model.  相似文献   
129.
Due to the broad impact of microfabrication technology on chemistry and biology, new methods to pattern and etch a variety of materials are being explored in a number of laboratories. Here, we report the design, fabrication, and operation of a glassy carbon (GC) microchip interfaced to a nanoelectrospray ionization source and a quadrupole mass spectrometer. The method involves standard photolithographic pattern transfer to a photoresist layer and anodization of the exposed GC substrate in basic electrolyte to produce a series of channels with well-defined wall structure. The performance of the microchip was evaluated with standard polymer and peptide samples.  相似文献   
130.
An intention requires us to carry out an action at a certain time or in an unscheduled time frame. In recent years, palmtop computerized devices with special functions have been developed that enable individuals to better remember their intentions. People record their intention in the device and are later reminded of their intention by a warning signal, such as an audible beep, that is presented along with a message about what is to be done. The present research investigated the psychological effects of the warning signals provided by palmtop reminding devices. Four experiments demonstrated that the effectiveness of an audible warning signal in the form of a signal was greatest early in the day. The interval between the signal and time to carry out the act, called here the anticipatory lag, did not significantly influence the timeliness of responses and remembering.  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