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   468篇
  免费   25篇
电工技术   7篇
综合类   1篇
化学工业   100篇
金属工艺   10篇
机械仪表   12篇
建筑科学   3篇
能源动力   9篇
轻工业   62篇
无线电   60篇
一般工业技术   76篇
冶金工业   133篇
原子能技术   3篇
自动化技术   17篇
  2023年   4篇
  2022年   6篇
  2021年   14篇
  2020年   2篇
  2019年   5篇
  2018年   8篇
  2017年   13篇
  2016年   8篇
  2015年   10篇
  2014年   7篇
  2013年   16篇
  2012年   9篇
  2011年   14篇
  2010年   9篇
  2009年   15篇
  2008年   14篇
  2007年   14篇
  2006年   8篇
  2005年   13篇
  2004年   11篇
  2003年   6篇
  2002年   19篇
  2001年   19篇
  2000年   14篇
  1999年   18篇
  1998年   53篇
  1997年   27篇
  1996年   29篇
  1995年   11篇
  1994年   12篇
  1993年   14篇
  1992年   4篇
  1990年   7篇
  1989年   7篇
  1988年   9篇
  1987年   7篇
  1986年   3篇
  1985年   4篇
  1984年   3篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1980年   4篇
  1978年   1篇
  1976年   7篇
  1975年   2篇
  1971年   1篇
  1970年   1篇
  1968年   1篇
  1966年   1篇
排序方式: 共有493条查询结果,搜索用时 312 毫秒
131.
BACKGROUND: Funazushi is a fermented sushi containing n3 polyunsaturated fatty acids. Moreover, the functionality of lactic acid fermentation foods has come to be expected. Funazushi is therefore worthy of study. Funazushi has a specific flavor which is either strongly liked or strongly disliked. We examined the components of funazushi and investigated their relation to preference. RESULTS: Many free amino acids with sweetness and/or umami were present in funazushi, but nucleic compounds were scarce as taste elements. Twelve kinds of volatile elements were detected in all samples, which were thought to form the basis of the flavor of funazushi, although a total of 30 or more kinds of volatile elements were detected from each sample. The smell greatly influenced the overall evaluation. Panelists who had not eaten funazushi before, or only rarely, showed a tendency to prefer the same sample, from which ketones, aldehydes, or acids did not volatilize so much. On the other hand, individual variation was large among panels who commonly ate funazushi. CONCLUSION: The smell and sourness of funazushi greatly influenced preference, especially in persons who had little experience of eating funazushi. Funazushi containing low ketone, aldehyde, or acid levels is suitable for the first eating experience. Copyright © 2008 Society of Chemical Industry  相似文献   
132.
In recent years, joint types in railway superstructure have shifted to continuous welded rails (CWRs), which can be constructed by various welding techniques to form uninterrupted rails several kilometres long. Because of the numerous advantages of this method, CWR systems are highly preferred today for the construction of new railway lines. The increase in the number of trains in operation is inducing fatigue damages, linking to life‐threatening risks in the rails as well as in trains' wheels and axles. In this study, CWR specimens formed by the flash butt‐welding process are investigated. Specimens extracted from rail sections are subjected to four‐point bending fatigue tests to establish S–N curves under various loading levels. The surfaces of those specimens which fail are then investigated in detail in order to determine the initiation points of the failures. The findings provide experimental data on the dynamic life cycle of CWR and identify the failure mechanism of the CWR system.  相似文献   
133.
This ultrastructural study showed that nonisotopic methanolic hafnium chloride and aqueous lead solution was an excellent new electron stain for enhancing TEM contrasts of fungal and plant cell structures. The ultrastructural definition provided by the new stain was often superior to that provided by conventional staining with uranyl acetate and lead. Definition of fine ultrastructure was also supported by quantitative data on TEM contrast ratios of organelles and components in fungal and plant cells. In particular, polysaccharides, which were localized in cell walls, glycogen particles, starch grains, and plant Golgi vesicle components, were much more reactive to the new stain than to the conventional one. The new nonisotopic stain is useful for enhancing the contrast of ultrastructure in biological tissues and is a safer alternative to uranyl acetate. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.  相似文献   
134.
135.
High density multilayer substrate technologies are indispensable to accommodate high input/outputs (I/Os) fine pitch area array integrated circuits (ICs), chip scale packages/ball grid arrays (CSP/BGAs) in the coming packaging generation. They must provide not only a high wiring density, but also an acceptable low cost, short turn around time (TAT) and reliability. Reduction of the number of layers is expected to be a reasonable solution for the conflicting demands. General approaches to reduce the layer count have been to decrease the size of the routing line width and spacing. However, they need changes in the manufacturing processes and materials, causing an increased cost. From escape routing design viewpoint, effects of routing manner on the layer count have been studied. A preferential routing creates specific pad geometry resulting in a high wiring efficiency. This effect can be estimated with an increase in the number of lines per layer routable as a contribution of "the hybrid channel," depending on capture pad pitch-pad diameter-line width-interline space relationship. It is one of the remarkable cases recognized that, within one line per channel rule, the preferential routing can be almost equivalent to that by two lines per channel with regard to the wireability. Its better effect on cost and TAT can also be expected compared with the two thinner sized lines per channel rule, since nothing changes in both manufacturing processes and materials is needed. This method is applicable immediately to packages and boards for assembly of the high I/O flip chips, CSPs, and BGAs.  相似文献   
136.
Single crystals of ternary borides ErRh3B (cubic,Pm3m), ErRh3B2 (monoclinic, C2/m) and ErRh4B4 (tetragonal, P42/nmc) have been grown from copper solution by slow cooling method. The electrical resistivity, oxidation resistivity and Vickers microhardness were studied. The electrical resistivities at room temperature of the (100) face of ErRh3B, (001) face of ErRh3B2 and (100) face of ErRh4B4 are 25.6 μΩ·cm, 50.0 μΩ·cm and 106.8 μΩ·cm, respectively. According to thermogravimetric and differential thermal analyses, the oxidation of ErRh3B, ErRh3B2 and ErRh4B4 start at 1030°C, 373°C and 690°C, respectively. The weight gain of the same compounds after heating in air up to 1200°C is 0.7%, 15.44% and 5.4%, respectively. The values of the Vickers microhardness for the (100) face of ErRh3B, the (100) face of ErRh3B2 and the (110) face of ErRh4B4 are 4.8–5.0 GPa, 10.4–10.9 GPa and 10.9–11.3 GPa, respectively. The effect of boron content and crystal structure of each compound on the electrical resistivity, oxidation resistivity and Vickers microhardness are discussed.  相似文献   
137.
This paper aims to develop a systematized theory on the thinking process at the ‘very early stage of design.’ Here, ‘very’ is used to exaggerate the beginning of design, which includes the time just prior to or the precise beginning of the so-called conceptual design. First, concept generation is segregated into two phases—the problem-driven phase and the inner sense-driven phase. With regard to theoretical approach, the concept generation process is discussed by comparing metaphor, abduction, and general design theory from the perspective of similarities and dissimilarities. In addition, property mapping, concept blending, and concept integration in thematic relation are explained methodologically. So far, these theories and methods have been discussed independently, and the relations among them have not been clarified. As a result, it was found that the concept generation process could be categorized into two types: first-order concept generation and high-order concept generation. Furthermore, it was shown that high-order concept generation is related to the inner sense-driven phase, whereas first-order concept generation is related to the problem-driven phase.  相似文献   
138.
Built-in torque sensing for Harmonic Drives is attractive since it maintains mechanical characteristics of the gear while providing detection of the transmitted torque. Torque sensing by using strain gauges has been studied, but is not widely used yet due to a relatively high signal fluctuation, which is generated by the gear operation. Characteristics of the signal fluctuation are analyzed in this paper, and a method to effectively compensate the signal fluctuation is proposed. The signal fluctuation is perfectly compensated by adjustment of the strain gauge sensitivities. A minimum number of strain gauges needed to compensate the signal fluctuation is derived. The experimental result with three strain gauges compensating the basic frequency component of the signal fluctuation is shown  相似文献   
139.
An integrated spectral imaging system constructed by synchronizing a programmable light source, a high‐speed monochrome camera, and a display device is proposed to produce tristimulus images of static and moving objects effectively in real time onto the display. This system is called the CIE‐XYZ display. Active spectral illuminants, containing both the device characteristics of camera and display, are projected onto object surfaces as time sequence. The images are captured synchronously by the camera and quickly transmitted to the display device in the RGB signal form so that the accurate tristimulus images are displayed. First, we describe the principle of the CIE‐XYZ tristimulus display. The theoretically optimal illuminants contain negative parts in the spectral curves. Second, we design practical illuminants with all positive spectral curves. The color images in our system are composed of the time sequence of RGB component images. Then, the synthesized color images on the display contain color artifacts when objects move fast. An image processing algorithm for correcting the motion color artifact is proposed based on optical flow estimation using a graphics processing unit. The comprehensive performance of the proposed system and algorithms is examined using both static and moving objects. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 329–340, 2015  相似文献   
140.
The multi-shot flash lamp annealing (FLA) method as a rapid annealing technique was developed for an electroless-plated Ni-P film on UV-surface-modified acrylonitrile–butadiene-styrene (ABS) in place of the conventional annealing method. The new multi-shot FLA method continuously irradiates a Xe flash discharge with low irradiance (<1?J?cm–2) with a frequency of 3?Hz. An adhesion strength between the electroless Ni-P film and ABS of more than 1.2?kN?m–1 was achieved in a short time of approximately 30?s; this adhesion strength was larger than that obtained in the conventional method of 1?h duration. The etching effect of the FLA method was assessed by a study of the surface morphologies of the Ni-P films. XRD spectra of the Ni-P films showed an improvement in the crystallinity of the films. Considering surface elemental analyses of the peeled Ni-P-film/ABS, a cohesive failure, which implies high adhesion, was observed in the ABS. The proposed FLA method is expected to efficiently improve the adhesion and significantly reduce the annealing time in the electroless plating process.  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