首页 | 官方网站   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   239篇
  免费   6篇
  国内免费   1篇
工业技术   246篇
  2023年   3篇
  2022年   7篇
  2021年   2篇
  2020年   5篇
  2018年   6篇
  2017年   4篇
  2016年   7篇
  2015年   4篇
  2014年   6篇
  2013年   16篇
  2012年   7篇
  2011年   10篇
  2010年   10篇
  2009年   6篇
  2008年   10篇
  2007年   5篇
  2006年   11篇
  2005年   12篇
  2004年   2篇
  2003年   4篇
  2002年   4篇
  2001年   2篇
  2000年   2篇
  1999年   5篇
  1998年   16篇
  1997年   11篇
  1996年   6篇
  1995年   2篇
  1994年   7篇
  1993年   4篇
  1992年   4篇
  1991年   1篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1981年   6篇
  1980年   5篇
  1978年   1篇
  1977年   7篇
  1976年   2篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1962年   1篇
排序方式: 共有246条查询结果,搜索用时 15 毫秒
51.
The system-level impacts of innovations often can be more significant than the direct, primary impacts in certain industries. In particular, these system interactions can be seen with large, complex multi-system constructed facilities. Approximately half of the 200 specific innovations identified in eleven recent long span and multi-segmental bridges are linked to other innovations. Three general types of ‘cluster’ interaction are system, actualizing, and complementary links. The system interactions are nurtured through coordinated innovation development programmes. The actualizing links connect one set of innovations to another set, to aid in their realization of the innovation and project objectives. The complementary links provide additional benefits through the joint use of multiple innovations. The results of these analyses provide significant new insight for innovation theory into the system-level interactions of innovations. Since the frequency of the linkages among the innovations appears to reflect the relative stability of the design and construction parameters, recent innovation trajectories may be more difficult to link effectively to other innovations. These innovation interactions can provide critical capabilities for achieving the project objectives, but must be identified and managed effectively to achieve desired performance levels.  相似文献   
52.
Transverse ion and neutral temperatures at the electron cyclotron resonance position were measured in an electron cyclotron resonance (ECR) plasma using a high-resolution optical emission spectroscopy of Doppler profiles of Ar and Ar+ transition. The transverse ion temperature increase from approximately 0.4 to 1.0 eV as the operating gas pressure is lowered from 1.0 to 0.1 mTorr. On the other hand, the transverse neutral temperature is much lower than the transverse ion temperature. By means of Langmuir probe measurement, large-amplitude potential fluctuation was observed at the ECR position under the low gas pressure. These observations suggest that the large-amplitude potential fluctuation directly affects the transverse ion temperature.  相似文献   
53.
13C NMR spectra of copolymers of methyl methacrylate and tert-butyl methacrylate with various chemical compositions, the homopolymers of the two methacrylates, and blends of the homopolymers with various blend ratios were subjected to principal component analysis. The first and second principal components correlated chemical composition and the randomness of comonomer sequence, respectively. Chemical composition of the copolymers was determined with high accuracy and precision by the partial least-squares regression without assignment of individual resonance peaks.  相似文献   
54.
This paper describes the construction and the performance of a distributed power generating system of photovoltaics (PV) using solar energy estimation. Instead of conventional batteries a new storage device, called energy capacitor system (ECaSS), is used for its various advantages. A procedure is described to estimate the PV output power by calculating solar radiation. To calculate the daily insolation, Hottel's equation and Liu-Jordan's equation have been used with some modification. The accuracy of the procedure is verified by comparing the calculated solar radiation with the practically measured one. To apply the procedure even in cloudy/rainy weather, the characteristic of the PV output in different weather conditions has been studied using 1-day-ahead weather forecasts. With an aim to set the optimum amount of buy power, a simulation program has been developed. The system is being operated in optimal economic mode in different weather conditions. The financial benefit and load-leveling capacity of the system have been studied and presented here. It was found that the system provides an excellent economic benefit for nonflat price of electricity and load-leveling facility with a good overall efficiency.  相似文献   
55.
The tribological performance of halogen-free ionic liquids at steel–steel and diamond-like carbon (DLC)–DLC contacts was investigated. Hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (ta-C) were used as test specimens. Friction tests were carried out on steel–steel, a-C:H–a-C:H, and ta-C–ta-C contacts by using a reciprocating cylinder-on-disk tribotester lubricated with two different types of halogen-free ionic liquids: 1-ethyl-3-methylimidazolium dicyanamide ([BMIM][DCN]) and 1-butyl-3-methylimidazolium tricyanomethanide ([BMIM][TCC]). From the results of friction tests, the ta-C–ta-C tribopair lubricated with [BMIM][DCN] or [BMIM][TCC] exhibited an ultralow friction coefficient of 0.018–0.03. On the other hand, ultralow friction was not observed at the steel–steel and a-C:H–a-C:H contacts. Measurements obtained with a laser scanning microscope and an atomic force microscope (AFM) showed that a chemical reaction film, derived from the ionic liquid lubricant used, was formed on the steel surfaces. However, this chemical reaction film was not observed on either of the DLC surfaces. The AFM results showed that there were high-viscosity products on the ta-C surfaces, that the wear tracks on the ta-C surfaces exhibited low frictional properties, and that the ta-C surfaces were extremely smooth after the friction tests. Based on these results, it was concluded that an ionic liquid–derived adsorbed film formed on the ta-C surface and resulted in the ultralow friction when lubricated with a halogen-free ionic liquid.  相似文献   
56.
Low‐molecular‐weight CXCR4 ligands based on known lead compounds including the 14‐mer peptide T140, the cyclic pentapeptide FC131, peptide mimetics, and dipicolylamine‐containing compounds were designed and synthesized. Three types of aromatic spacers, 1,4‐phenylenedimethanamine, naphthalene‐2,6‐diyldimethanamine, and [1,1′‐biphenyl]‐4,4′‐diyldimethanamine, were used to build four pharmacophore groups. As pharmacophore groups, 2‐pyridylmethyl and 1‐naphthylmethyl are present in all of the compounds, and several aromatic groups and a cationic group from 1‐propylguanidine and 1,1,3,3‐tetramethyl‐2‐propylguanidine were also used. Several compounds showed significant CXCR4 binding affinity, and zinc(II) complexation of bis(pyridin‐2‐ylmethyl)amine moieties resulted in a remarkable increase in CXCR4 binding affinity.  相似文献   
57.
In this paper, we approximate the distribution of disturbances by the Edgeworth series distribution and propose a Bayesian analysis in a nonnormal AR(1) model. We derive the posterior distribution of the autocorrelation and the posterior odds ratio for unit roots hypothesis in the AR(1) model when the first four cumulants of the Edgeworth series distribution are finite and the higher order cumulants are negligible. We also apply the posterior analysis to eight real exchange rates and investigate whether these exchange rates behave like a random walk or not.  相似文献   
58.
In a robotic cell, assembly robots have to grasp parts in various shapes robustly and accurately even under some uncertainties in the initial poses of the parts. For this purpose, it is necessary to develop a universal robotic hand and robust grasping strategies, i.e. finger motions that can achieve planned grasping robustly against the initial pose uncertainty of parts. In this paper, we propose a methodology to plan robust grasping strategies of a universal robotic hand for assembling parts in various shapes. In our approach, parts are aligned toward planned configurations during grasping actions, and the robustness of grasping strategies is analyzed and evaluated based on pushing operation analysis. As an application example, we plan robust grasping strategies for assembling a three-dimensional puzzle, and experimentally verify the robustness and effectiveness of the planned strategies for this assembly task.  相似文献   
59.
We investigated the acceptor specificity of a thermostable trehalose phosphorylase from Thermoanaerobacter brockii ATCC 35047 (TbTP) was examined using beta-D-glucose-1-phosphate (beta-G1P) as a glucosyl donor and oligosaccharides as the acceptor. Oligosaccharides with a reducing-end glucose residue as the C-6 substituent (e.g., isomaltose, gentiobiose, melibiose, isomaltotriose, and isopanose) were found to be successful acceptors. The transfer products of isomaltose, gentiobiose, and melibiose were isolated and characterized as 6-O-alpha-D-glucopyranosyl trehalose (alpha-GlcTre), 6-O-beta-D-glucopyranosyl trehalose (beta-GlcTre), and 6-O-alpha-D-galactopyranosyl trehalose (alpha-GalTre), respectively. To produce alpha-GalTre, a novel nonreducing trisaccharide, the reaction conditions of alpha-GalTre were examined using trehalose as a glucosyl donor. As a result, the yield of alpha-GalTre reached 40.5%.  相似文献   
60.
Isomaltodextrin (IMD) is a novel highly branched α-glucan ingredient that has potential applications in foods as a promising source of dietary fibre. In this study, we assessed the incorporation of IMD in baked products and its effect on dough rheology and physico-textural characteristics of wheat breads. IMD was added to wheat flour to reach the US FDA level of ‘good’ source of fibre (10% IMD). Use of the straight-dough method with IMD and regular dough mixing time (8 min) resulted in less elastic doughs and resulting breads displayed lower cohesiveness, springiness and chewiness compared to the control bread. A modified straight-dough method, with longer mixing time (36 min) and adjusted water level (70%), and a sponge-and-dough method were used to allow gluten structure to more fully hydrate and develop. With IMD addition, the modified straight-dough (36 min dough mixing time) and sponge-and-dough methods yielded enhanced dough elasticity compared to the original straight-dough method. Breadmaking methods were identified (improved straight-dough and sponge-and-dough) whereby IMD could be added at a 'good source' of fibre level with loaf appearance and texture similar to breads without IMD.  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-23

京公网安备 11010802026262号