全文获取类型
收费全文 | 578篇 |
免费 | 9篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 53篇 |
金属工艺 | 12篇 |
机械仪表 | 4篇 |
建筑科学 | 35篇 |
矿业工程 | 3篇 |
能源动力 | 10篇 |
轻工业 | 28篇 |
水利工程 | 2篇 |
无线电 | 37篇 |
一般工业技术 | 90篇 |
冶金工业 | 146篇 |
原子能技术 | 6篇 |
自动化技术 | 157篇 |
出版年
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 27篇 |
2012年 | 14篇 |
2011年 | 20篇 |
2010年 | 19篇 |
2009年 | 12篇 |
2008年 | 18篇 |
2007年 | 27篇 |
2006年 | 21篇 |
2005年 | 21篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 7篇 |
2001年 | 16篇 |
2000年 | 7篇 |
1999年 | 21篇 |
1998年 | 65篇 |
1997年 | 40篇 |
1996年 | 26篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 18篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 3篇 |
排序方式: 共有587条查询结果,搜索用时 15 毫秒
1.
The phenotypic characteristics of three Serpulina pilosicoli strains isolated from humans with diarrhoea (WesB, Kar, Hrm7) and two porcine S. pilosicoli strains isolated from pigs with intestinal spirochaetosis (1648, 3295), were compared with the type strain of the species P43/6/78T (T = type strain) and other intestinal spirochaetes within the genus Serpulina. All S. pilosicoli strains had a characteristic ultrastructural appearance, displayed similar growth rates, hydrolysed hippurate, lacked beta-glucosidase activity, utilised D-ribose as a growth substrate, and had similar sensitivities to rifampicin and spiramycin. The only consistent phenotypic characteristic that differentiated human strains from porcine strains of S. pilosicoli was that the human strains all utilised the pentose sugar D-xylose. These distinguishing phenotypic traits appear useful for identifying S. pilosicoli. 相似文献
2.
The application of micro- and nanofabrication processes to the development of hybrid synthetic and biological systems may enable the production of new devices such as controllable transporters, gears, levers, micropumps, or microgenerators powered by biological molecular motors. However, engineering these hybrid devices requires fabrication processes that are compatible with biological materials such as kinesin motor proteins and microtubules. In this paper, the effects of micro- and nanofabrication processing chemicals and resists on the functionality of casein, kinesin, and microtubule proteins are systematically examined to address the important missing link of the biocompatibility of micro- and nanofabrication processes needed to realize hybrid system fabrication. It is found that both casein, which is used to prevent motor denaturation on surfaces, and kinesin motors are surprisingly tolerant of most of the processing chemicals examined. Microtubules, however, are much more sensitive. Exposure to the processing chemicals leads to depolymerization, which is partially attributed to the pH of the solutions examined. When the chemicals were diluted in aqueous buffers, a subset of them no longer depolymerized microtubules and in their diluted forms still worked as resist removers. This approach broadens the application of micro- and nanofabrication processes to hybrid synthetic and biological system fabrication. 相似文献
3.
4.
P Oroszlan S Wicar G Teshima S L Wu W S Hancock B L Karger 《Analytical chemistry》1992,64(14):1623-1631
This paper examines the retention behavior of recombinant DNA-derived human growth hormone (rhGH) in reversed-phase chromatography and its separation from the closely related N-methionyl variant (Met-hGH). It is first shown that retention for rhGH decreases with increasing column temperature when 1-propanol (1-PrOH) is used as organic modifier. On the other hand, retention increases with temperature when acetonitrile (CH3CN) is employed. The differences in behavior for the two organic modifiers could be related to conformational changes in the protein as determined by solution and adsorption intrinsic fluorescence spectroscopy. Specifically, desorption and elution of rhGH using 1-PrOH could be correlated with a solvent-induced conformational change, with retention decreasing with increasing temperature due to the increasing ease of structural alteration. On the other hand for CH3CN the increase in retention correlated with temperature rise was related to a partial structural change yielding a more hydrophobic species. In this case, a surface-driven process is suggested. The work then turned to the separation of rhGH and Met-hGH where it was found for both organic modifiers optimum separation occurred at 45 degrees C and pH 6.5. Separate studies revealed that during the conformational change Met-hGH appeared more hydrophobic than rhGH since protein-protein aggregation was observed at a lower 1-PrOH concentration. It is suggested that this hydrophobic difference, which was optimized under the conditions cited above, resulted in the separation. The study demonstrates the importance of conformational changes in retention behavior and separation of protein samples. 相似文献
5.
This paper describes the implementation and experimental studies of an adaptive self-optimizing pole shifting power system stabilizer. Using an Intel iSBC386/21 single-board computer, the adaptive power system stabilizer has been tested on a physical model of a single-machine infinite-bus power system. Under different operating conditions and disturbances, the behavior of the proposed adaptive stabilizer was investigated. Comparison has also been made to a digital-type conventional fixed-parameter power system stabilizer. Results of the experimental studies show that the proposed adaptive stabilizer outperforms the conventional stabilizer. 相似文献
6.
Microbiological results from milk samples obtained premilking and postmilking for the diagnosis of bovine intramammary infections. 总被引:1,自引:0,他引:1
Bacteriological culture results were compared between 336 pairs of quarter milk samples collected premilking and postmilking. Using a positive result on either premilking or postmilking samples as the definitive diagnosis, premilking sampling sensitivity was 91% for Staphylococcus aureus, 91% for coagulase-negative staphylococci, and 97% for Streptococcus other than agalactiae. Postmilking sampling sensitivities were 81, 45, and 58%, respectively, for the same pathogens. Requiring both premilking and postmilking samples for the definitive diagnosis, specificities were 92, 86, and 95% for premilking sampling alone and 96, 98, and 99% for postmilking sampling alone. Such differences in specificity would result in major differences in predictive value of a positive culture for herds with a low prevalence. Multiple isolates were significantly more common from premilking samples. 相似文献
7.
8.
Bill Hancock 《Computer Fraud & Security》1998,1998(7):16-18
One of the problems of computer security is deciding on how much security is necessary for proper control of system and network assets. This gets down to the concept of threat assessment or, more specifically, what do you have and who would want it? While it sounds relatively simple to state, it's not that easy to assess corporate network threats unless you approach things in a structured manner. In this article, the basics of threat assessment are discussed with some thought placed on how to identify who wants to take what you have or hurt you in some way. 相似文献
9.
A study has been made of the by-products formed during the autoxidation of a number of drying oil modified alkyd resins when catalysed by a range of different promoters. The by-product components have been separated and identified using GC-MS methods, and their composition correlated with that of the naturally occurring fatty acids present in the individual drying oils. Mechanisms are proposed to account for the formation of the components. 相似文献
10.
C. Kinney Hancock Robert L. Burdick 《Journal of the American Oil Chemists' Society》1956,33(4):175-177
Summary The modified indirect conductivities and oven-dry moisture percentages were determined on mine Samples of cooked cottonseed
meats (1.8 to 13.9% water). Statistical treatment of the data yields the following results: (1) equation of the regression
line, {fx177-1} (2) correlation coefficient, 0.998; (3) standard deviation from the regression line, 0.27% water.
Ten replicate determinations made on each of two samples containing 2.7 and 7.7% water showed standard deviations of 0.07
and 0.08% water.
These results show that the accuracy and precision of the modified indirect conductivity method are satisfactory for practical
applications. For a consecutive series of determinations the average time required per determination was about 9 min. This
time could be reduced to about 5 min. by using duplicate sets of stirring apparatus.
Describes data obtained in research conducted cooperatively by the Cotton Research Committee of Texas and the Texas Engineering
Experiment Station. 相似文献