全文获取类型
收费全文 | 8525篇 |
免费 | 470篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 64篇 |
综合类 | 18篇 |
化学工业 | 2002篇 |
金属工艺 | 201篇 |
机械仪表 | 166篇 |
建筑科学 | 342篇 |
矿业工程 | 31篇 |
能源动力 | 241篇 |
轻工业 | 757篇 |
水利工程 | 114篇 |
石油天然气 | 23篇 |
无线电 | 538篇 |
一般工业技术 | 1756篇 |
冶金工业 | 1438篇 |
原子能技术 | 44篇 |
自动化技术 | 1270篇 |
出版年
2023年 | 65篇 |
2022年 | 142篇 |
2021年 | 211篇 |
2020年 | 169篇 |
2019年 | 201篇 |
2018年 | 226篇 |
2017年 | 210篇 |
2016年 | 246篇 |
2015年 | 192篇 |
2014年 | 323篇 |
2013年 | 592篇 |
2012年 | 487篇 |
2011年 | 696篇 |
2010年 | 474篇 |
2009年 | 432篇 |
2008年 | 488篇 |
2007年 | 455篇 |
2006年 | 377篇 |
2005年 | 346篇 |
2004年 | 291篇 |
2003年 | 272篇 |
2002年 | 240篇 |
2001年 | 122篇 |
2000年 | 111篇 |
1999年 | 115篇 |
1998年 | 155篇 |
1997年 | 133篇 |
1996年 | 119篇 |
1995年 | 105篇 |
1994年 | 98篇 |
1993年 | 73篇 |
1992年 | 78篇 |
1991年 | 39篇 |
1990年 | 38篇 |
1989年 | 51篇 |
1988年 | 56篇 |
1987年 | 45篇 |
1986年 | 41篇 |
1985年 | 61篇 |
1984年 | 53篇 |
1983年 | 56篇 |
1982年 | 41篇 |
1981年 | 34篇 |
1980年 | 38篇 |
1979年 | 25篇 |
1978年 | 31篇 |
1977年 | 29篇 |
1976年 | 29篇 |
1975年 | 18篇 |
1974年 | 14篇 |
排序方式: 共有9005条查询结果,搜索用时 15 毫秒
1.
Vivien Walsh Robin Roy Margaret Bruce Stephen Potter 《Creativity & Innovation Management》1993,2(2):78-86
A series of studies of top European and other firms has revealed patterns of design management associated with commercial success. Firms that invest resources and professional expertise in product and industrial design in traditional and new industries have been commercially more successful than firms that pay less attention to these aspects of design. As an industry matures there is a shift in emphasis from design associated with technological innovation, to designs supporting technical improvements, and then to supporting user needs, fashion and product variants. These issues are illustrated through the history of the evolution of the bicycle. 相似文献
2.
The object-oriented approach to integrating knowledge data, and models is examined. Under the object-oriented paradigm, everything is an object, which is itself an encapsulation of data and methods to manipulate and access the data within the object. Thus knowledge, data, and models can be defined as special kinds of objects. Active knowledge/data language (KDL), a functional object-oriented database system is considered, covering the active-KDL-type system and functions, and query-driven simulation 相似文献
3.
Properties and Performance of Cation-Doped Ceria Electrolyte Materials in Solid Oxide Fuel Cell Applications 总被引:1,自引:0,他引:1
Christopher Milliken Sivaraman Guruswamy Ashok Khandkar 《Journal of the American Ceramic Society》2002,85(10):2479-2486
Cation-doped CeO2 electrolyte has been evaluated in single-cell and short-stack tests in solid oxide fuel cell environments and applications. These results, along with conductivity measurements, indicate that an ionic transference number of ∼0.75 can be expected at 800°C. Single cells have shown a power density >350 mW/cm2 . Multicell stacks have demonstrated a peak performance of >100 mW/cm2 at 700°C using metallic separators. 相似文献
4.
W. J. Reilly J. B. Schwartz E. S. Gahli Christopher T. Rhodes 《Drug development and industrial pharmacy》1994,20(8):1511-1515
Spherical dosage forms have been reported to be an efficient and effective method for delivering drugs into the body and controlling their dissolution rate. Substantial work has been conducted in these laboratories illustrating the advantages of microcrystalline cellulose-based spheres for these purposes. Through various methodologies, but most routinely the extrusion and marumerization technique, it has been determined by Funck, et al. that not more than 50% drug can be incorporated into a sphere formulation without the addition of other binders.
Because of the nature of the extrusion and marumerization manufacturing process, the type of drug being processed and the resultant particle size requirements of the spheres, the percent of spheres falling outside the desired particle size can range from between 3% and 20%. For this reason and the possibility of operator errors, our objective was to determine the parameters which needed monitoring when reprocessing was necessary. 相似文献
Because of the nature of the extrusion and marumerization manufacturing process, the type of drug being processed and the resultant particle size requirements of the spheres, the percent of spheres falling outside the desired particle size can range from between 3% and 20%. For this reason and the possibility of operator errors, our objective was to determine the parameters which needed monitoring when reprocessing was necessary. 相似文献
5.
Adrian Thomas Christopher D. Gilson Tanveer Ahmed 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(1):73-79
Equipment was developed to measure the time for complete gelling of sodium alginate fibres in calcium chloride solution, taken as the time to achieve maximum tensile strength. The effects of fibre diameter, alginate concentration, alginate composition and calcium chloride concentration on gelling time were investigated. A diffusional model, developed to predict the gelling time, agreed with experimental results except for the effect of calcium ion concentration which was modelled empirically. 相似文献
6.
EuLisp has an integrated object system with reflective capabilities. We discuss some example applications which use these facilities to experiment with some advanced and powerful concepts, namely, finalization, virtual shared memory and persistence. A secondary goal is to attempt to illustrate the additional possibilities of metaobject programming over non-metalevel techniques. 相似文献
7.
Sabha Kesraoui-Ouki Christopher R. Cheeseman Roger Perry 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1994,59(2):121-126
This paper assesses the potential of natural zeolite utilization as a low-cost ion-exchange and sorbent material in pollution control and recovery of metals. The improvement of the purity of natural zeolites coupled with their chemical modification capabilities in order to provide specific properties may provide a cost-effective alternative for the treatment of heavy metal contaminated soil and water. The application of natural zeolites in industrial pollution control is becoming important and the level of technical effort is increasingly expanding. The extent of application is unlikely to be related solely to their low cost, but also to improved properties and performance characteristics, which will advance the practical implementation of natural zeolites' technology. 相似文献
8.
Roger Norman Rothon Christopher Mark Liauw Graham Clayton Lees Wayne Christopher Edward Schofield 《The Journal of Adhesion》2002,78(7):603-628
The interaction of ammonium stearate (AS) and γ-aminopropyltriethoxysilane (APS) treatments with a magnesium hydroxide flame retardant filler and their effects on its use in an ethylene vinyl acetate copolymer compound have been investigated. The work has shown clear evidence of changes in the structure of the surface layers formed on the filler as the amount of additive is increased and the levels at which these occur can be correlated with theoretical monolayer quantities. Infrared (IR) spectroscopy data suggest that the stearate coating changes from a half salt to a full salt as the coating level is increased and that the APS coating on the filler initially has a significant bicarbonate content, presumably due to reaction with atmospheric carbon dioxide. The effect of coating level on the melt flow rate, insoluble matrix content, crystallisation behaviour, tensile properties, limiting oxygen index, and ageing of the filled compound has been studied. Distinct trends have been observed, many of which can be correlated with the structure of the filler surface layers. Of particular importance is the observation that, unlike APS, excess stearate appears to promote detrimental ageing effects. 相似文献
9.
William E. Cooper Jr. Christopher S. Deperno Johnny Arnett 《Journal of chemical ecology》1994,20(11):2867-2881
Experimental tests showed that poststrike elevation in tongue-flicking rate (PETF) and strike-induced chemosensory searching (SICS) in the gila monster last longer than reported for any other lizard. Based on analysis of numbers of tongue-flicks emitted in 5-min intervals, significant PETF was detected in all intervals up to and including minutes 41–45. Using 10-min intervals, PETF lasted though minutes 46–55. Two of eight individuals continued tongue-flicking throughout the 60 min after biting prey, whereas all individuals ceased tongue-flicking in a control condition after minute 35. The apparent presence of PETF lasting at least an hour in some individuals suggests that there may be important individual differences in duration of PETF. PETF and/or SICS are present in all families of autarchoglossan lizards studied except Cordylidae, the only family lacking linguallly mediated prey chemical discrimination. However, its duration is known to be greater than 2-min only in Helodermatidae and Varanidae, the living representatives of Varanoidea. That prolonged PETF and SICS are typical of snakes provides another character supporting a possible a varanoid ancestry for Serpentes. Analysis of 1-min intervals showed that PETF occurred in the first minute. A review of the literature suggests that a pause in tongue-flicking and delay of searching movements are absent in lizards and the few nonvenomous colubrid snakes tested. The delayed onset of SICS may be a specific adaptation of some viperid snakes to allow potentially dangerous prey to be rendered harmless by venom following voluntary release after envenomation and preceding further physical contact with the prey. 相似文献
10.
The International Water Management Institute (IWMI) has made important changes in the thrust of its research programmesince 1995. These new thrusts include attention to the implications of increasing water scarcity at the global level; the adoption of a river basin paradigm leading to new insights into opportunities for water conservation and productivity; application of new information technologies and quantitative analytical techniques; and a stronger focus on policy, institutional issues, health and environment, and social inequities in access to water. This paper describes these changes and provides an overview of the remaining papers in this special issue of Water Resources Development. 相似文献