全文获取类型
收费全文 | 743篇 |
免费 | 6篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 76篇 |
金属工艺 | 12篇 |
机械仪表 | 16篇 |
建筑科学 | 28篇 |
矿业工程 | 8篇 |
能源动力 | 6篇 |
轻工业 | 79篇 |
水利工程 | 2篇 |
石油天然气 | 6篇 |
无线电 | 65篇 |
一般工业技术 | 96篇 |
冶金工业 | 281篇 |
原子能技术 | 6篇 |
自动化技术 | 53篇 |
出版年
2021年 | 7篇 |
2018年 | 6篇 |
2016年 | 7篇 |
2014年 | 10篇 |
2013年 | 33篇 |
2012年 | 8篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 13篇 |
2008年 | 23篇 |
2007年 | 18篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 16篇 |
1998年 | 66篇 |
1997年 | 29篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 23篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 14篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 28篇 |
1976年 | 21篇 |
1975年 | 17篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1971年 | 5篇 |
1970年 | 5篇 |
1969年 | 6篇 |
1966年 | 6篇 |
1955年 | 5篇 |
排序方式: 共有749条查询结果,搜索用时 15 毫秒
41.
42.
Yen-Ping C. Hsieh Albert M. Pearson Ian D. Morton William T. Magee 《Journal of the science of food and agriculture》1980,31(9):943-949
Percentage changes in the amino acid content upon heating with different components in a synthetic model meat flavour mixture were followed during different stages in development of the system. Heating of ten different amino acids with a simple sugar mixture (glucose, ribose and xylose) resulted in losses of approximately 95, 58, 38 and 37% of the cysteine, methionine, leucine and isoleucine, respectively, whereas the other amino acids decreased by 19–31%, but the ammonia (NH3) content by only 5%. On heating gelatin with the simple sugar mixture, tyrosine and phenylalanine losses amounted to about 58 and 40%, respectively, while the other amino acids declined by 27–37% and the NH3 content by some 12%. Heating of the composite model system (gelatin, added amino acids and simple sugars) resulted in losses of about 94, 60 and 55% of the cysteine, methionine and histidine, respectively, while the other amino acids decreased by 20–35% and the NH3 content by 15%. The possible role of some of the amino acids in the development of the synthetic meat flavour system is discussed in view of these findings. 相似文献
43.
Lowry MI Bartelt-Hunt SL Beaulieu SM Barlaz MA 《Environmental science & technology》2008,42(19):7444-7451
Models describing the behavior of organic chemicals in landfills can be useful to predict their fate and transport and also to generate input data for estimates of exposure and risk. The landfill coupled-reactor (LFCR) model developed in this work simulates a landfill as a series of fully mixed reactors, each representing a daily volume of waste. The LFCR model is a numerical model allowing time-variable input parameters such as gas generation, and cover type and thickness. The model was applied to three volatile organic chemicals (acetone, toluene, benzene) as well as naphthalene and the chemical warfare agent sarin under three landfill conditions (conventional, arid, bioreactor). Sarin was rapidly hydrolyzed, whereas naphthalene was largely associated with the landfill solid phase in all scenarios. Although similar biodegradation rates were used for acetone and toluene, toluene was more persistent in the landfill due to its hydrophobicity. The cover soil moisture content had a significant impact on gaseous diffusive losses. 相似文献
44.
The effect of grafting styrene onto low-density polyethylene on the diffusion and solubility of benzene and n-hexane in the graft copolymer has been investigated. The diffusion coefficient at zero concentration Dc = 0 for both benzene and n-hexane decreased with the amount of styrene grafting in the polyethylene–styrene graft copolymer membrane. The free volume parameters of the polyethylene–styrene graft copolymer were calculated using benzene and n-hexane as the diffusing species. Results show that there is a large decrease in free volume as grafting proceeds and the effect is more pronounced at low levels of grafting. Solubility was found to be a function of the per cent grafting, there being a 50%–90% increase in benzene solubility in a 26% graft compared to polyethylene. The increase in solubility for n-hexane was considerably lower. The effect of crystallinity on the free volume parameters has also been calculated. 相似文献
45.
M. Dombsky T. Achtzehn G. Hackman J. Lassen A.C. Morton E.J. Prime 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,264(1):117-124
An intense beam of 26gAl has been developed for accelerated beam experiments at TRIUMF’s ISAC facility. Studies of the on-line production of Al radionuclides from thick silicon carbide targets have been performed as part of a program of beam development for astrophysical reaction studies at ISAC. While the release of short-lived Al nuclides from SiC was found to be slow, development of new target material forms and high-power target containers has allowed operation of SiC targets with proton currents of up to 70 μA on target. In addition, operation with the TRIUMF resonant ionization laser ion source (TRILIS) has produced 26gAl beam intensities of 5.1 × 1010 s−1. 相似文献
46.
Suspension cultures of finely divided soybean cells established from callus were incubated with sodium [1(14)C] acetate for periods up to 86 hr. Lipids and fatty acids were analyzed for radioactivity in samples harvested at logarithmic time periods. Incorporation of acetate into cell lipid was directly proportional to the logarithm of time up to 32 hr, after an initial lag of 4-6 hr. Most of the lipid radioactivity was found in the phospholipid fraction, and all common soybean fatty acids became labeled within 6 hr. The order of labeling and distribution of radioactivity with time were essentially the same as in tissues from intact growing plants. These results support the concept of sequential desaturation of oleic acid in the cells. It was concluded that valid studies of the biosynthesis of common lipids in the soybean can be carried out for extended periods of time by use of undifferentiated cells in suspension cultures. 相似文献
47.
Fleishman Edwin A.; Roberts Millard M.; Friedman Morton P. 《Canadian Metallurgical Quarterly》1958,42(2):129
"Fourteen auditory and printed aptitude measures were administered to students prior to entry into training for radiotelegraphy. These 14 measures, together with a criterion of proficiency in learning to receive Morse Code, were subjected to factor analysis study. Five factors were identified as Visualization, Verbal Knowledge, Speed of Closure, Auditory Rhythm Perception, and Auditory Perceptual Speed. Three of these, Auditory Rhythm Perception, Auditory Perceptual Speed, and Speed of Closure, were found to contribute to the criterion of subsequent code proficiency." (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
49.
5 bit, silicon-based, X-band phase shifter using a hybrid pi/t high-pass/low-pass topology 总被引:1,自引:0,他引:1
Morton M.A. Comeau J.P. Cressler J.D. Mitchell M. Papapolymerou J. 《Microwaves, Antennas & Propagation, IET》2008,2(1):19-22
A hybrid pi/t bit passive topology is presented to enable a significant reduction in the die area for a high-pass/low-pass phase shifter is presented. A hybrid-topology 5 bit digital X-band phase shifter was designed, fabricated and tested using a 200 GHz, 0.13 mum SiGe bipolar complementary metal oxide semiconductor (BiCMOS) technology. Size and performance characteristics are presented as a contrast to an all-pi phase shifter recently presented by Comeau et al. using the same SiGe BiCMOS technology and design goals. With similar bit passive performance to the all-pi design, the hybrid shifter allows for a total shifter die-area reduction of 50.5%. The absolute phase error of the shifter was less than plusmn13 from 8 to 12 GHz, with an average insertion loss of -20 dB. 相似文献
50.
Shaw and his colleagues [Shaw, B., Han, J., Kim, E., Gustafson, D., Hawkins, R., Cleary, C., et al. (2007). Effects of prayer and religious expression within computer support groups on women with breast cancer. Psycho-oncology, 16(7), 676–687] examined religious expression in breast cancer (BC) online support groups (OSG). Using Pennebaker’s LIWC text analysis to assess religious expression, they found that the more frequent the expression of words related to religion the lower the levels of negative emotions and the higher the levels of health self-efficacy and functional well-being. Our study goal was to replicate their findings. Specifically, we tested their central hypothesis that the percentage of religious words written by members of BC OSG’s are associated with improvement in psychological outcomes. Five BC OSG’s from our previous work [Lieberman, M. A., & Goldstein, B. (2005a). Not all negative emotions are equal: The role of emotional expression in online support groups for women with breast cancer. Psycho-oncology. 15, 160–168; Lieberman, M. A., & Goldstein, B. (2005b). Self-help online: An outcome evaluation of breast cancer bulletin boards. Journal of Health Psychology, 10(6), 855–862] studied 91 participants at baseline and 6 months post. Significant changes in depression and quality of life was found over time. In the current study linear regressions examined the relationship between religious statements and outcomes. The results did not support the hypotheses of a positive relationship between religious expression and positive outcome in both OSG samples. Reviews of studies examining the role of religion in health outcomes report equivocal results on the benefits of religious expression. 相似文献