全文获取类型
收费全文 | 1531篇 |
免费 | 47篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 87篇 |
综合类 | 6篇 |
化学工业 | 356篇 |
金属工艺 | 27篇 |
机械仪表 | 24篇 |
建筑科学 | 29篇 |
能源动力 | 60篇 |
轻工业 | 120篇 |
水利工程 | 5篇 |
石油天然气 | 6篇 |
无线电 | 142篇 |
一般工业技术 | 262篇 |
冶金工业 | 274篇 |
原子能技术 | 54篇 |
自动化技术 | 130篇 |
出版年
2022年 | 18篇 |
2021年 | 28篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 18篇 |
2017年 | 24篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 23篇 |
2013年 | 54篇 |
2012年 | 58篇 |
2011年 | 63篇 |
2010年 | 71篇 |
2009年 | 73篇 |
2008年 | 71篇 |
2007年 | 55篇 |
2006年 | 41篇 |
2005年 | 47篇 |
2004年 | 45篇 |
2003年 | 47篇 |
2002年 | 39篇 |
2001年 | 39篇 |
2000年 | 30篇 |
1999年 | 32篇 |
1998年 | 104篇 |
1997年 | 73篇 |
1996年 | 51篇 |
1995年 | 48篇 |
1994年 | 42篇 |
1993年 | 31篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 16篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 26篇 |
1985年 | 22篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1973年 | 8篇 |
排序方式: 共有1582条查询结果,搜索用时 15 毫秒
81.
Fukano H Tamotsu Z Eiji S Kimitsuna W Teruyuki N 《Journal of Bioscience and Bioengineering》2002,93(1):20-24
Qbeta replicase functioning in Escherichia coli is an RNA-dependent RNA polymerase composed of one phage-coded subunit and three host-coded proteins: ribosomal protein S1, and protein elongation factors EF-Tu and EF-Ts. Qbeta replicase lacking ribosomal protein S1 (alpha-less replicase) is capable of replicating some small RNAs. We attempted to create functional alpha-less replicase by co-expression of the mRNAs that code for the subunits of alpha-less replicase in a rabbit reticulocyte cell-free translation system. Replicase activity, however, could not be detected when both EF-Tu and EF-Ts were co-expressed with the phage-coded subunit. On the other hand, active alpha-less replicase was obtained when an EF-Ts-EF-Tu fusion protein was co-expressed with the phage-coded subunit. Consequently, we succeeded in generating genetically engineered active alpha-less Qbeta replicase which functions in a eukaryotic cell-free system. 相似文献
82.
Hiroshi Kageyama Mitsuhide Miyamoto Hajime Akimoto Shigeyuki Nishitani Toshihiro Sato Toshio Miyazawa 《Journal of the Society for Information Display》2006,14(4):345-351
Abstract— A common‐decoder architecture for a data‐driver circuit fabricated by using a polysilicon process has been developed. The architecture achieves a compact circuit and low‐power consumption. In application to an integrated polysilicon data driver for small‐sized displays, this architecture reduces the area of the data driver by removing the vertical bus lines that occupy a large area. It also suppresses the power consumption of the data bus by reducing the number of driven lines in the data bus during word‐to‐word transitions from six to two. By using a conventional 4‐μm design rule, we fabricated an active‐matrix OLED (AMOLED) panel with an integrated six‐bit data‐driver circuit with 384 outputs. The driver circuit had a height of 2.6 mm and a pitch between output lines of 84 μm. The maximum power consumption of the driver was only 5 mW, i.e., 3.8 mW for logic‐data transfer and 1.2 mW for reference‐voltage source. Furthermore, we also fabricated an active‐matrix LCD (AMLCD) panel including driver circuits of the same type as the integrated elements. Six‐bit full‐color images were successfully displayed on both panels. 相似文献
83.
Yong Gao June Kinoshita Elizabeth Wu Eric Miller Ryan Lee Andy Seaborne Steve Cayzer Tim Clark 《Journal of Web Semantics》2006,4(3):222
SWAN – a Semantic Web Application in Neuromedicine – is a project to develop an effective, integrated scientific knowledge infrastructure for Alzheimer Disease (AD) researchers, enabled by Semantic Web technology and deployed on Alzforum (www.alzforum.org), a scientific web community for AD research. This infrastructure may later be deployed for research communities in other neuromedical disorders. SWAN incorporates the full biomedical research knowledge lifecycle in its ontological model, including support for personal data organization, hypothesis generation, experimentation, lab data organization, and digital pre-publication collaboration. Community, laboratory, and personal digital resources may all be organized and interconnected using SWAN's common semantic framework. 相似文献
84.
H Iida Y Narita H Kado A Kashikura S Sugawara Y Shoji T Kinoshita T Ogawa S Eberl 《Canadian Metallurgical Quarterly》1998,39(1):181-189
The pyruvate dehydrogenase complex (PDC) plays a key role in the anaerobic mitochondrial metabolism of the parasitic nematode Ascaris suum. A cDNA coding for an A. suum pyruvate dehydrogenase kinase (APDK) has been cloned and sequenced from poly(A)+ RNA isolated from adult A. suum muscle.2 APDK exhibited significant sequence identity to mammalian PDKs. Nucleotide sequence analysis of the APDK cDNA revealed a 22-nucleotide spliced leader, characteristic of many nematode mRNAs, a 5'-UTR of 6 nucleotides, an open reading frame of 1197 nucleotides, and a 3'-UTR of 101 nucleotides that included a putative polyadenylation signal. The open reading frame predicted a protein of 399 amino acids with a molecular weight of 45,402 that included a putative 18-aminoacid leader peptide. Recombinant APDK (rAPDK) was functionally expressed in Escherichia coli with a his tag at its N-terminus and purified to apparent homogeneity on Ni-NTA-agarose. Recombinant APDK was a dimer and was not autophosphorylated and its activity was stimulated in the presence of APDK-deficient adult A. suum muscle PDC presumably by the binding of APDK to the dihydrolipoyl transacetylase (E2) core of the complex. After binding to the core, rAPDK activity was stimulated by elevated NADH/NAD+ and acetyl CoA/CoA ratios within the same ranges as observed for the native APDK. Immunoblotting suggested that native APDK focused as a series of 43-kDa spots (pI 6.1-6.8) on two-dimensional gels of the purified adult A. suum muscle PDC. 相似文献
85.
86.
This letter discusses the problem of designing a feedback compensator that attains the infinite gain margin under the uncertainties of feedback gains. A sufficient condition is given for the existence of compensators and then it is shown that the condition becomes necessary subject to the requirement that the feedback system is decoupled. The nonlinear case is also discussed. 相似文献
87.
Kojima Hiroomi Kinoshita Yasuaki Hikita Mitsuaki Tabuchi Toyoji 《Electronics letters》1980,16(12):445-446
Velocity and propagation loss of surface shear waves are measured on free-space and metallised surfaces of LiNbO3 crystals along the x-axis of rotated Y-cut plates as a function of rotation about the x-axis between 35° and 70°. The coupling factor obtained from the velocities is 0.20 for a 35° rotated Y-cut plate and 0.09 for a 70° plate. The coupling factor changes linearly with the rotation angle. The propagation losses over the whole range measured here are less than 5 dB/cm on both free-space and on metallised surfaces. These losses are fairly low and very favourable for fabricating s.a.w. filters. 相似文献
88.
89.
The electrochemical oxidation of a high surface area carbon black (1000 m2/g) was investigated in 96% H3PO4 at 135°C. The total anodic current, the amount of CO2 evolved and the oxygen content of the carbon were all measured as a function of time and potential. Two anodic processes occurred: the formation of a surface oxide and the evolution of CO2. Both decreased with time but at different rates so that CO2 evolution eventually became the major reaction. Various mechanisms to define the corrosion processes are discussed. 相似文献
90.
Ribotyping and a study of transmission of Staphylococcus aureus collected from food preparation facilities 总被引:1,自引:0,他引:1
Kishimoto M Hioki Y Okano T Konuma H Takamizawa K Kashio H Kasuga F 《Journal of food protection》2004,67(6):1116-1122
Food poisoning from Staphylococcus aureus is sometimes caused by improper handling of food items in food preparation facilities. Prevention of contamination by employees is particularly important in facilities where a significant amount of food preparation is performed by hand. Some experiments have been performed to describe bacterial cross-contamination in the food preparation process, but there have been few studies of cross-contamination in actual food preparation facilities. Aiming to shed light on the transmission of S. aureus in food preparation facilities, this study collected samples of 66 strains of this bacterium from the fingers of food preparation staff, foodstuffs, prepared foods, cooking utensils, and cooking equipment and typed them with the ribotyping method. S. aureus from the same ribogroup was detected on the hands of a study participant, a faucet, knife, frying pan, and a salad, indicating that bacteria found on the hands of the study participant was transmitted to cooking utensils and prepared foods. Transmission (from a faucet to a frying pan handle) of bacteria by another person, a third party, was also detected. 相似文献