全文获取类型
收费全文 | 339篇 |
免费 | 14篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 81篇 |
金属工艺 | 13篇 |
机械仪表 | 4篇 |
建筑科学 | 3篇 |
能源动力 | 15篇 |
轻工业 | 12篇 |
无线电 | 29篇 |
一般工业技术 | 47篇 |
冶金工业 | 98篇 |
原子能技术 | 7篇 |
自动化技术 | 35篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 10篇 |
2013年 | 21篇 |
2012年 | 10篇 |
2011年 | 12篇 |
2010年 | 13篇 |
2009年 | 6篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 11篇 |
1998年 | 32篇 |
1997年 | 28篇 |
1996年 | 17篇 |
1995年 | 11篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有353条查询结果,搜索用时 15 毫秒
1.
2.
Advanced IC packaging for the future applications 总被引:2,自引:0,他引:2
The performance of electronic equipment is improving rapidly. Portable electronic equipment requires smaller and thinner packaging systems for saving space and miniaturization. In addition, highly integrated, high-speed applications demand improved electrical performance to minimize noise effects. As a result of these considerations, the role of IC packaging has expanded from its traditional role of protecting the integrity and performance of an IC, to being a central factor in the development of electronic system concepts. In developing the optimum system, packaging technology must be a prime design consideration to ensure optimum performance, reliability, and cost. Soldering technology and Printed Wiring Board (PWB) routing density are two of the major technological issues facing miniaturized packaging systems today. Chip Scale Package (CSP), which is a new concept in packaging technology has been introduced. This is an ideal technology to enable the design and manufacture of the next generation of electronic equipment, while overcoming many of the technological issues facing system development 相似文献
3.
4.
Shoji Eguchi 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(5):977-987
Recent progress of synthesis of C60 derivatives functionalized with hetero-cycles is reviewed, focusing attention on [4+2]- and [3+2] cycloaddition methodologies and oxidative heterocyclization. 相似文献
5.
Recovery of serum proteins using cellulosic affinity membrane modified by immobilization of CU2+ ion
An affinity membrane was prepared from a porous cellulose membrane, and adsorption and recovery of serum proteins were investigated from the viewpoint that affinity membranes are efficacious against separation and purification of biomaterials. Into the cellulose membrane, iminodiacetate (IDA) group that acts as a ligand to metal ions was introduced (Cell–IDA membrane), and then Cu2+ ion was immobilized (Cell–IDA–Cu membrane). Bovine serum albumin (BSA) and γ-globulin (BγG), which are the major proteins in blood, were adopted as model proteins to be separated. The Cell–IDA–Cu membrane had large adsorption capacity for these proteins despite the low degree of modification. The amounts of proteins adsorbed on the Cell–IDA–Cu membrane increased with increasing pH, and BγG was adsorbed more than BSA. High protein recoveries from the Cell–IDA–Cu membrane were obtained. The separation of these proteins was also conducted under the optimum conditions of adsorption and recovery, and BγG was concentrated more than BSA although the initial concentration of BγG was lower than that of BSA. © 1996 John Wiley & Sons, Inc. 相似文献
6.
Prof. Dr. Fumitaka Kudo Jiahao Zhang Shusuke Sato Dr. Akane Hirayama Prof. Dr. Tadashi Eguchi 《Chembiochem : a European journal of chemical biology》2019,20(19):2458-2462
Pactamycin is an antibiotic produced by Streptomyces pactum with antitumor and antimalarial properties. Pactamycin has a unique aminocyclitol core that is decorated with 3-aminoacetophenone, 6-methylsaliciate, and an N,N-dimethylcarbamoyl group. Herein, we show that the adenylation enzyme PctU activates 3-aminobenzoic acid (3ABA) with adenosine triphosphate and ligates it to the holo form of the discrete acyl carrier protein PctK to yield 3ABA-PctK. Then, 3ABA-PctK is N-glycosylated with uridine diphosphate-N-acetyl-d -glucosamine (UDP-GlcNAc) by the glycosyltransferase PctL to yield GlcNAc-3ABA-PctK. Because 3ABA is known to be a precursor of the 3-aminoacetophenone moiety, PctU appears to be a gatekeeper that selects the appropriate 3-aminobenzoate starter unit. Overall, we propose that acyl carrier protein-bound glycosylated 3ABA derivatives are biosynthetic intermediates of pactamycin biosynthesis. 相似文献
7.
NAD+‐Dependent Dehydrogenase PctP and Pyridoxal 5′‐Phosphate Dependent Aminotransferase PctC Catalyze the First Postglycosylation Modification of the Sugar Intermediate in Pactamycin Biosynthesis 下载免费PDF全文
Dr. Akane Hirayama Jinmiao Chu Ena Goto Dr. Fumitaka Kudo Prof. Dr. Tadashi Eguchi 《Chembiochem : a European journal of chemical biology》2018,19(2):126-130
The unique five‐membered aminocyclitol core of the antitumor antibiotic pactamycin originates from d ‐glucose, so unprecedented enzymatic modifications of the sugar intermediate are involved in the biosynthesis. However, the order of the modification reactions remains elusive. Herein, we examined the timing of introduction of an amino group into certain sugar‐derived intermediates by using recombinant enzymes that were encoded in the pactamycin biosynthesis gene cluster. We found that the NAD+‐dependent alcohol dehydrogenase PctP and pyridoxal 5′‐phosphate dependent aminotransferase PctC converted N‐acetyl‐d ‐glucosaminyl‐3‐aminoacetophonone into 3′‐amino‐3′‐deoxy‐N‐acetyl‐d ‐glucosaminyl‐3‐aminoacetophenone. Further, N‐acetyl‐d ‐glucosaminyl‐3‐aminophenyl‐β‐oxopropanoic acid ethyl ester was converted into the corresponding 3′‐amino derivative. However, PctP did not oxidize most of the tested d ‐glucose derivatives, including UDP‐GlcNAc. Thus, modification of the GlcNAc moiety in pactamycin biosynthesis appears to occur after the glycosylation of aniline derivatives. 相似文献
8.
Mechanism‐Based Trapping of the Quinonoid Intermediate by Using the K276R Mutant of PLP‐Dependent 3‐Aminobenzoate Synthase PctV in the Biosynthesis of Pactamycin 下载免费PDF全文
Akane Hirayama Dr. Akimasa Miyanaga Prof. Dr. Fumitaka Kudo Prof. Dr. Tadashi Eguchi 《Chembiochem : a European journal of chemical biology》2015,16(17):2484-2490
Mutational analysis of the pyridoxal 5′‐phosphate (PLP)‐dependent enzyme PctV was carried out to elucidate the multi‐step reaction mechanism for the formation of 3‐aminobenzoate (3‐ABA) from 3‐dehydroshikimate (3‐DSA). Introduction of mutation K276R led to the accumulation of a quinonoid intermediate with an absorption maximum at 580 nm after the reaction of pyridoxamine 5′‐phosphate (PMP) with 3‐DSA. The chemical structure of this intermediate was supported by X‐ray crystallographic analysis of the complex formed between the K276R mutant and the quinonoid intermediate. These results clearly show that a quinonoid intermediate is involved in the formation of 3‐ABA. They also indicate that Lys276 (in the active site of PctV) plays multiple roles, including acid/base catalysis during the dehydration reaction of the quinonoid intermediate. 相似文献
9.
Hiroshi Inoue Koshi Sekizawa Koichi Eguchi Hiromichi Arai 《Journal of the American Ceramic Society》1997,80(3):584-588
A coating of barium hexaaluminate (Ba0.75 Al11.0 O17.25 ) on an α-SiC substrate and the thermal stability of the formed film were investigated for a high-temperature catalytic application. The film prepared by sol coating consisted of BaAl2 Si2 O8 and α-Al2 O3 phases and always contained many cracks or exfoliations after heating at 1200C. A hexaaluminate porous film was successfully formed by slurry coating without void formation at the interface between the film and the substrate and exfoliation due to the formation of the intermediate layer after heating at 1200°C. The microstructure of the film remained unchanged, even after heating at 1300°C. 相似文献
10.
Steam reforming of methanol on various supported Cu catalysts was examined. Supports strongly affected catalyst activity and, among the catalysts tested, Cu catalyst supported on large-surface-area ZnAl2O4 showed the highest activity, which, to the best of our knowledge, was higher than those for the supported catalysts reported so far. For supported Cu catalysts, two species were observed. One was a dispersed Cu species having strong interaction between Cu and support, and the other was an isolated Cu species. The activity of the former species strongly depended on supports. 相似文献