全文获取类型
收费全文 | 4950篇 |
免费 | 117篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 46篇 |
综合类 | 3篇 |
化学工业 | 793篇 |
金属工艺 | 146篇 |
机械仪表 | 97篇 |
建筑科学 | 189篇 |
矿业工程 | 18篇 |
能源动力 | 92篇 |
轻工业 | 492篇 |
水利工程 | 56篇 |
石油天然气 | 32篇 |
武器工业 | 1篇 |
无线电 | 346篇 |
一般工业技术 | 651篇 |
冶金工业 | 1483篇 |
原子能技术 | 52篇 |
自动化技术 | 573篇 |
出版年
2022年 | 49篇 |
2021年 | 62篇 |
2020年 | 49篇 |
2019年 | 63篇 |
2018年 | 68篇 |
2017年 | 62篇 |
2016年 | 77篇 |
2015年 | 65篇 |
2014年 | 95篇 |
2013年 | 228篇 |
2012年 | 155篇 |
2011年 | 218篇 |
2010年 | 174篇 |
2009年 | 177篇 |
2008年 | 212篇 |
2007年 | 185篇 |
2006年 | 180篇 |
2005年 | 156篇 |
2004年 | 145篇 |
2003年 | 121篇 |
2002年 | 144篇 |
2001年 | 105篇 |
2000年 | 125篇 |
1999年 | 116篇 |
1998年 | 321篇 |
1997年 | 205篇 |
1996年 | 141篇 |
1995年 | 107篇 |
1994年 | 113篇 |
1993年 | 96篇 |
1992年 | 72篇 |
1991年 | 58篇 |
1990年 | 80篇 |
1989年 | 54篇 |
1988年 | 50篇 |
1987年 | 51篇 |
1986年 | 44篇 |
1985年 | 50篇 |
1984年 | 48篇 |
1983年 | 36篇 |
1982年 | 21篇 |
1981年 | 42篇 |
1980年 | 46篇 |
1979年 | 30篇 |
1978年 | 27篇 |
1977年 | 49篇 |
1976年 | 69篇 |
1975年 | 26篇 |
1974年 | 22篇 |
1972年 | 22篇 |
排序方式: 共有5070条查询结果,搜索用时 15 毫秒
1.
2.
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
3.
4.
Effect of pretreatments and freezing rate on the firmness of potato tissue after a freeze–thaw cycle
Sergio Carbonell Jorge C. Oliveira & Alan L. Kelly 《International Journal of Food Science & Technology》2006,41(7):757-767
The texture of potato tissue after a freeze–thaw process using different freezing rates and different pretreatments was analysed, in order to select the best strategy for optimum preservation of the textural characteristics of pre‐frozen potato. Ten blanching conditions were tested and a two‐step blanching process with calcium chloride (0.07 g mL?1) proved the most effective in protecting the tissue after a freeze–thaw process (maximum load force around 10–55% of the raw tissue, depending on potato batch, for air‐blast freezing and 20–60% for immersion freezing). Vacuum impregnation at 100 and 400 mbar, even when followed by different pre‐drying treatments to remove excess water, was very detrimental to resistance to a freeze–thaw process (maximum load force below 10% of the raw tissue for air‐blast freezing and below 20% for immersion freezing). Microstructure analysis confirmed better tissue integrity retention with ethyleneglycol immersion freezing instead of air‐freezing. Differences were found between batches with a 6‐month difference in storage time, indicating that the fresher batch was more suitable for freezing. 相似文献
5.
This paper highlights the role of the faculty member in recruiting students currently enrolled in B.S. programs in engineering and the sciences into full-time pursuit of a graduate-level engineering degree. The faculty member is demonstrated to be in a unique position to influence such students, providing strong counterforces to a confluence of attitudes and pressures experienced during the B.S. experience which effectively create a barrier to full-time engineering graduate study. We analyze this barrier via the method of force field analysis, and demonstrate that effective recruitment into full-time graduate study must be based on a four-fold strategy of education, expectations, improved B.S. experience and better control of the B.S. environment. Approaches to implement these strategies are discussed. 相似文献
6.
M Kelly 《Canadian Metallurgical Quarterly》1996,17(2):60-62
Based on his experience with treatment of 112 children the author considers that severe and various disturbances of the rectum abturative apparatus function arising from surgical interventions in the anorectal area require the differentiated approach to choice of the method of surgical correction of the incontinence. The transplantation of the denervated muscle, transplantation of the vascular-nervous thoraco-dorsal flap, a lavsan band were used to make a pubo-rectal loop, plasty of the outer and inner sphincters being performed mainly with local tissues. 相似文献
7.
8.
In response to D. Cicchetti's (see record 1998-01884-002) and W. A. Mason's (see record 1998-01884-003) commentaries, this article scrutinizes infant maltreatment in monkeys and its public health implications. Studies of infant abuse and neglect in monkeys have used operational definitions based on (a) adult behavior or (b) adult behavior and infant outcome (depending on data available for analysis). Direct comparisons between the incidence of maltreatment in monkey and human populations can be only tentative as a result of differences in operational definitions of maltreatment. A simplified version of the ecological-transactional model of maltreatment can be used in research with nonhuman primates, and different species can be used to model different aspects of the human phenomenon. Although abuse and neglect take different forms in animals and humans, research with animal models can make an important contribution to elucidating the adaptive function, if any, of child maltreatment and the proximate mechanisms underlying its occurrence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
T. R. Guilinger M. J. Kelly J. R. Scully T. M. Christensen D. Ingersoll J. A. Knapp R. I. Ewing W. H. Casey S. S. Tsao 《Journal of Fusion Energy》1990,9(3):299-304
We describe several electrochemical methods used to investigate the possibility of cold fusion phenomena in palladium and titanium tritide cathodes. We performed long-term (up to 77 days) electrolysis experiments with electrochemical cells of the University of Utah type at current densities as high as 1 A/cm2, while monitoring neutron and tritium levels. With some cells, we pulsed the current to determine if neutron bursts would result. In another cell, we used titanium tritide as the cathode to determine if D-T reactions yielding neutrons would occur. In no instance were levels of neutrons or tritium significantly above background except in the titanium tritide cell where isotopic exchange, occcurring between the electrode and the electrolyte, resulted in significant tritium levels. We also combined x-ray photoelectron spectroscopy (XPS) and electrochemical hydrogen permeation experiments to determine the effectiveness of various Pd surface treatment procedures on the resultant electrochemical hydrogen absorption efficiency. Electroanalytical and thermal desorption/gas analysis techniques indicated the maximum loading of H in Pd was to a ratio of HPd=0.8. 相似文献
10.
Sykes EC Han P Kandel SA Kelly KF McCarty GS Weiss PS 《Accounts of chemical research》2003,36(12):945-953
Adsorbate interactions and reactions on metal surfaces have been investigated using scanning tunneling microscopy. The manners in which adsorbates perturb the surface electronic structure in their vicinity are discussed. The effects these perturbations have on other molecules are shown to be important in overlayer growth. Interactions of molecules with surface steps are addressed, and each molecule's electron affinity is shown to dictate its adsorption sites at step edges. Standing waves emanating from steps are demonstrated to effect transient molecular adsorption up to 40 A away from the step edge. Halobenzene derivatives are used to demonstrate how the surface is important in aligning reactive intermediates. 相似文献