全文获取类型
收费全文 | 358篇 |
免费 | 3篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 56篇 |
金属工艺 | 2篇 |
机械仪表 | 4篇 |
建筑科学 | 3篇 |
能源动力 | 11篇 |
轻工业 | 24篇 |
水利工程 | 3篇 |
无线电 | 51篇 |
一般工业技术 | 55篇 |
冶金工业 | 112篇 |
原子能技术 | 3篇 |
自动化技术 | 26篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 6篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 12篇 |
1998年 | 39篇 |
1997年 | 27篇 |
1996年 | 19篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1976年 | 11篇 |
1975年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有361条查询结果,搜索用时 15 毫秒
351.
Digital signage systems have found many interesting applications in the realms of advertising, entertainment and education.
One of the most prevalent challenging issues faced by current Local Area Network (LAN) based Digital signage network architectures
is that their difficulty in porting to wireless ubiquitous environments. While popularity of wireless LANs promotes such architectural
improvement, Traditional thin/thick client based architectures suffer inefficiency and scalability issues introduced by use
of proprietary signage content formats. Use of such content formats to store signage contents is less optimal since it could
lead to content redundancy, difficulty in creating, managing signage contents and scalability issues. As a solution for this
issue we propose a Smart Client based digital signage architecture that uses XAML (an XML based declarative GUI language)
contents for expressing its signage displays. While Smart Clients can better tolerate communication disruptions which are
quite frequent in wireless environments, use of XAML based open content format promotes use of simple tools and variety of
devices for signage content creation and management over the Internet in a ubiquitous environment. We successfully applied
this generic architecture to a prototype digital signage system called Infoshare and report its robustness in withstanding
network disruptions. We evaluate the easiness of editing XAML based signage contents by comparing Infoshare with a popular
LAN based digital signage system which uses proprietary content formats. We demonstrate scalability of Infoshare signage service
in terms of hardware resources by deploying it in different hardware platforms. 相似文献
352.
In order to improve anaerobic digester productivity, raising the microbial mass in the reactor and the prediction of changes in the biomass is required. In this study the possibilities for using near-infrared spectroscopy (NIR) to monitor methanogen density in a biogas process was examined. Methane production from H2 and CO2 was carried out with acclimated-methanogens with fed-batch substrate gas (H2/CO2, 80:20 v/v) at pH 7 and 37°C. The cells of the methanogens were washed and dried, and then original NIR spectra for predicting methanogen density were recorded. The specified absorption spectra were collected and examined. As a result, absorption spectrum peaks were found to be predominantly based on alpha proteins and lipids mainly from the cytoplasm and cell membranes of the methanogens. Furthermore, NIR was used to monitor the methane fermentation system using acetic acid as substrate. The responses from NIR analysis were correlated to methanogen density of fermentation broth by partial least-squares regressions. The correlation coefficient (R), model standard error of calibration (SEC) and standard error of prediction (SEP) of the test calibration for methanogen density were 0.99, 0.14 gl−1 and 0.55 gl−1, respectively. For volatile fatty acids (acetic acid) R, SEC and SEP were 0.99, 0.36 gl−1 and 0.63 gl−1, respectively. The results indicated that within the range of the density of methanogens and the concentration of acetic acid used in this study, it was possible to monitor the important variables of methanogen density and acetate concentration simultaneously in pure substrate-fed anaerobic digesters. 相似文献
353.
Porous granular ceramic adsorbents containing dispersed aluminum and iron oxides were synthesized by impregnating with salt solutions followed by precipitation at 600°C. In the present work detailed studies were carried out to investigate the effect of contact time, adsorbent dose, initial solution pH and co-existing anions. Characterization studies on the adsorbent by SEM, XRD, EDS, and BET analysis were carried out to clarify the adsorption mechanism. The adsorbents were sphere in shape, 2-3mm in particle size, highly porous and showed specific surface area of 50.69 sq m/g. The fluoride adsorption capacity of prepared adsorbent was 1.79 mg/g, and the maximum fluoride removal was obtained at pH 6. Both the Langmuir and Freundlich isotherm models were found to represent the measured adsorption data well. The experimental data were well explained with pseudo-second-order kinetic model. Results from this study demonstrated potential utility of Al/Fe dispersed in porous granular ceramics that could be developed into a viable technology for fluoride removal from aqueous solution. 相似文献
354.
Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor 总被引:5,自引:0,他引:5
An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO3−-N50 mg L−1) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8 h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO3−-N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO2 produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate. 相似文献
355.
Ryusuke Tanaka Kazuhiro Shigeta Yoshimasa Sugiura Hideo Hatate Teruo Matsushita 《Lipids》2014,49(4):385-396
Hydroxy lipids (L-OH) and 4-hydroxy-2-hexenal (HHE) levels as well as other parameters such as lipid level, lipid class, fatty acid composition, and other aldehydes levels in the liver of diseased fish were investigated. Although significant differences in lipid level, lipid class, fatty acid composition, and other aldehyde levels were not always observed between normal and diseased fish, L-OH and HHE levels were significantly higher in the liver of the diseased fish than in that of the normal fish cultured with the same feeds under the same conditions. In the liver of puffer fish (Fugu rubripes) infected with Trichodina, L-OH and HHE levels significantly increased from 25.29 ± 5.04 to 47.70 ± 5.27 nmol/mg lipid and from 299.79 ± 25.25 to 1,184.40 ± 60.27 nmol/g tissue, respectively. When the levels of HHE and other aldehydes in the liver of the normal and diseased puffer fish were plotted, a linear relationship with a high correlation coefficient was observed between HHE and propanal (r 2 = 0.9447). Increased L-OH and HHE levels in the liver of the diseased fish and a high correlation between HHE and propanal in the liver of the normal and diseased fish were also observed in flat fish (Paralichthys olivaceus) infected with streptococcus, yellowtail (Seriola quinqueradiata) infected with jaundice, and amberjack (S. purpurascens) infected with Photobacterium damselae subsp. piscicida. 相似文献
356.
Hideyuki Kobayashi Akihiko Sugiura 《IEEJ Transactions on Electrical and Electronic Engineering》2012,7(4):383-389
We propose a system to estimate the traffic congestion distance using IEEE 802.15.4, that is extended by multicommunication frequency division multiplexing. Our proposed system is developed at 20% equipped rate, where five lanes are considered. Furthermore, in our proposed system, it is assumed that the equipped rate in all lanes increases. Our proposed method can estimate an error rate lower than 10% approximately at on equipped rate greater than 50%. Additionally, we use 16 terminals in the actual environment. From the actual experiment, we find that our proposed method involving the use of communication pattern 2 is 300% faster than the existing method. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
357.
Imaging mass spectrometry is becoming a popular visualization technique in the medical and biological sciences. For its continued development, the ability to both visualize and identify molecules directly on the tissue surface using tandem mass spectrometry (MSn) is essential. We established an imaging system based on a matrix-assisted laser/desorption ionization quadrupole ion trap time-of-flight type instrument (AXIMA-QIT, Shimadzu, Kyoto, Japan), which was compatible with both imaging and highly sensitive MSn. In this paper, we present the operating conditions of the AXIMA-QIT as an imaging instrument and introduce the data converter we developed that is available free of charge. The converted data can be applied to Biomap, the commonly used visualization software. For the feasibility experiments, we demonstrated the visualization of phospholipids, glycolipid, and tryptic-digested proteins in the mouse cerebellum. The visualized lipids were successfully identified by MSn directly on the tissue surface, with a strong ability to isolate precursor ions. In the analysis of tryptic-digested proteins, we compared the product ion spectra between AXIMA-QIT and a tandem TOF-type instrument. The results confirmed that AXIMA-QIT can provide a high quality of product ion spectra even on the tissue surface. 相似文献
358.
Li J Shimizu K Utsumi M Nakamoto T Sakharkar MK Zhang Z Sugiura N 《Journal of Bioscience and Bioengineering》2011,111(6):695-701
Information is limited on the potential for microcystins (MCs) degradation by carrier-attached biofilms obtained in winter that were not exposed to detectable levels of MCs in the preceding months. Under controlled laboratory conditions, we confirmed that microcystin-LR (MCLR) was effectively biodegraded within 5.5 days in cultures of the biofilm sampled in winter. Quantitative polymerase chain reaction (qPCR) assays revealed that seasonal variations in the MCLR-degradation potential of the biofilm were closely related to the initial MCLR-degrader population in the biofilm. Indigenous MCLR-degraders in the biofilm could accumulate by exposure to natural MCLR in the water column, accelerating MCLR-degradation. The qPCR assay suggested that MCLR may be a primary substrate for the degraders in the presence of another labile organic carbon associated with the biofilm under the present study conditions. qPCR and PCR-denaturing gradient gel electrophoresis (DGGE) for 16S rDNA demonstrated that the overall bacterial population from the winter biofilm rapidly increased with the MCLR-degrader population and remained stable after day 3.5, while the overall bacterial community structure shifted throughout the entire biodegradation period. This study is important to the in-depth understanding of microbial degradation of MCs and could facilitate the bioremediation of MCs in polluted habitats. 相似文献
359.
An allosteric ribozyme has been designed using the hammerhead ribozyme as the active site and aflavin-specific RNA aptamer as a regulatory site. We constructed six variants with a series of base pairs in the linker region (stem II). Under single turnover conditions, kinetic studies were carried out in the absence and presence of flavin mononucleotide (FMN). Interestingly, FMN addition did not influence the cleavage rate of constructs with a 5-6 bp linker but stimulated the catalytic activity of those bearing a shorter linker. In particular, the apparent k cat of Rz3 increases by approximately 10-fold upon addition of saturating amounts of FMN. To determine the rate constants( K m4and k cat), the ribozyme regulated most effectively by FMN was further investigated. FMN mainly affected the k cat value, reflecting the rate limiting conformational change step of the overall cleavage reaction, depending on helix formation in stem II. Probably, FMN influences the orientation of structures necessary for the cleavage reaction through stem II formation. The result of chemical modification revealed that binding of FMN to the aptamer domain induced the helix formation in stem II required for catalytic activity. Therefore, a specific FMN-mediated allosteric interaction seems to promote a conformational alteration from an open to a closed structure in stem II. The concept of conformational modification in the allosteric effect is consistent with other allosteric enzymes, suggesting that such a conformational change is a fundamental feature of allosteric enzymes in biological systems. 相似文献
360.
Sato N Sugiura Y Tanaka T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2012,53(1):39-44
Several DNA extraction methods have been officially introduced to detect genetically modified soybeans, but the choice of DNA extraction kits depend on the nature of the samples, such as grains or processed foods. To overcome this disadvantage, we examined whether the GM quicker kit is available for both grains and processed foods. We compared GM quicker with four approved DNA extraction kits in respect of DNA purity, copy numbers of lectin gene, and working time. We found that the DNA quality of GM quicker was superior to that of the other kits for grains, and the procedure was faster. However, in the case of processed foods, GM quicker was not superior to the other kits. We therefore investigated an unapproved GM quicker 3 kit, which is available for DNA extraction from processed foods, such as tofu and boiled soybeans. The GM quicker 3 kit provided good DNA quality from both grains and processed foods, so we made a minor modification of the GM quicker-based protocol that was suitable for processed foods, using GM quicker and its reagents. The modified method enhanced the performance of GM quicker with processed foods. We believe that GM quicker with the modified protocol is an excellent tool to obtain high-quality DNA from grains and processed foods for detection of genetically modified soybeans. 相似文献