全文获取类型
收费全文 | 1005篇 |
免费 | 30篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 39篇 |
综合类 | 60篇 |
化学工业 | 55篇 |
金属工艺 | 186篇 |
机械仪表 | 53篇 |
建筑科学 | 26篇 |
矿业工程 | 1篇 |
能源动力 | 13篇 |
轻工业 | 285篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 50篇 |
一般工业技术 | 176篇 |
冶金工业 | 24篇 |
原子能技术 | 19篇 |
自动化技术 | 67篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 12篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 39篇 |
2013年 | 149篇 |
2012年 | 75篇 |
2011年 | 102篇 |
2010年 | 58篇 |
2009年 | 82篇 |
2008年 | 47篇 |
2007年 | 35篇 |
2006年 | 51篇 |
2005年 | 21篇 |
2004年 | 30篇 |
2003年 | 17篇 |
2002年 | 13篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 20篇 |
1997年 | 58篇 |
1996年 | 20篇 |
1995年 | 10篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 4篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 15篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1975年 | 5篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1967年 | 2篇 |
1962年 | 1篇 |
1960年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有1061条查询结果,搜索用时 15 毫秒
91.
LEE Hyeon-deok SON Myeong-jo OH Min-jae LEE Hyung-woo KIM Tae-wan 《中国科学:信息科学(英文版)》2012,(5):1019-1031
In early 2000,large domestic shipyards introduced shipbuilding 3D computer-aided design (CAD) to the hull production design process to define manufacturing and assembly information.The production design process accounts for most of the man-hours (M/H) of the entire design process and is closely connected to yard production because designs must take into account the production schedule of the shipyard,the current state of the dock needed to mount the ship’s block,and supply information.Therefore,many shipyards are investigating the complete automation of the production design process to reduce the M/H for designers.However,these problems are still currently unresolved,and a clear direction is needed for research on the automatic design base of manufacturing rules,batches reflecting changed building specifications,batch updates of boundary information for hull members,and management of the hull model change history to automate the production design process.In this study,a process was developed to aid production design engineers in designing a new ship’s hull block model from that of a similar ship previously built,based on AVEVA Marine.An automation system that uses the similar ship’s hull block model is proposed to reduce M/H and human errors by the production design engineer.First,scheme files holding important information were constructed in a database to automatically update hull block model modifications.Second,for batch updates,the database’s table,including building specifications and the referential integrity of a relational database were compared.In particular,this study focused on reflecting the frequent modification of building specifications and regeneration of boundary information of the adjacent panel due to changes in a specific panel.Third,the rollback function is proposed in which the database (DB) is used to return to the previously designed panels. 相似文献
92.
模板的安全性和隐私性是掌纹系统实际应用的关键问题,然而生物特征保护的多项指标通常相互冲突并且难以同时满足.作为解决上述冲突的一种可撤销掌纹编码算法,PalmPhasor实现了高效、安全的掌纹认证.建立了系统分析PalmPhasor性能的完整框架.为了便于具体分析,将情景分为4种情况,并且提供了支持相应分析的预备知识,包括辅助定理以及Gabor滤波掌纹图像实部和虚部分布特性.在统计学基础上建立的理论分析和实验结果均表明:即使在用户口令被盗的情况下,多方向分数级融合增强的PalmPhasor算法也可以同时有效地满足可撤销生物特征的4项指标. 相似文献
93.
94.
EFFECTS OF OIL DROPLET AND AGAR CONCENTRATION ON GEL STRENGTH AND MICROSTRUCTURE OF O/W EMULSION GEL 总被引:1,自引:0,他引:1
KYUNG-HEE KIM SHOICHI GOHTANI RYUICHI MATSUNO YOSHIMASA YAMANO 《Journal of texture studies》1999,30(3):319-335
The effects of oil droplet size and agar concentration on gel strength and microstructure of emulsion gels were investigated by compression test and cryoscanning electron microscope (Cryo-SEM). At all agar concentrations, the compressive stress values of emulsion gels were lower than those of the oil-free gels. Compressive stress and energy were significantly affected by oil droplet size and agar concentration, but compressive strain was not. SEM observation revealed that the overall volume of void spaces decreased and strand compactness increased with increasing agar concentration. Gels containing oil droplets had some void spaces between the gel network and the oil droplets. The strands of emulsion gels did not cover the oil globules completely, a phenomenon which was also observed for the gel with high agar concentration. 相似文献
95.
An agile manufacturing workcell design 总被引:1,自引:0,他引:1
QUINN ROGER D. CAUSEY GREG C. MERAT FRANK L. SARGENT DAVID M. BARENDT NICK A. NEWMAN WYATT S. VELASCO JR VIRGILIO B. PODGURSKI ANDY JO JU-YEON STERLING LEON S. KIM YOOHWAN 《IIE Transactions》1997,29(10):901-909
This paper introduces a design for agile manufacturing worked Is intended for light mechanical assembly of products made from similar components (i.e., parts families). We define agile manufacturing as the ability to accomplish rapid changeover from the assembly of one product to the assembly of a different product. Rapid hardware changeover is made possible through the use of robots, flexible part feeders, modular grippers, and modular assembly hardware. The division of assembly, feeding, and unloading tasks between multiple robots is examined with prioritization based upon assembly time. Rapid software changeover will be facilitated by the use of a real-time, object-oriented software environment utilizing graphical simulations for off-line software development. An innovative dual VMEbus controller architecture permits an open software environment while accommodating the closed nature of most commercial robot controllers. These agile features permit new products to be introduced with minimal downtime and system reconfiguration. 相似文献
96.
Canola Phytase: Isolation and Characterization 总被引:1,自引:0,他引:1
Two phytase isoenzymes were isolated from 8-day germinated canola cv Regent. Gel filtration chromatography of an ammonium sulfate fractionated extract on Sephadex G-100 produced one peak with phytase activity. The phytase fraction was separated into two isoenzymes by DEAE-cellulose chromatography. The optimum pH was 4.5–5.0 and 5.0 for the phytase isoenzymes 1 and 2, respectively. Both isoenzymes exhibited maximum activity at 50°C. Km values at pH 5.0 were 0.36 and 0.25 mM for phytase 1 and 2 isoenzymes, respectively, while molecular weight determination showed both fraction were identical with a molecular weight of 70,100 ± 4,000 daltons. 相似文献
97.
Daily meat consumption produces a lot of bone waste, and dumped bone waste without treatment would result in environmental hazards. Conventional treatment methods of waste bones have some disadvantages. Herein, an investigation of bone waste treated using thermal plasma technology is presented. A high-temperature plasma torch operated at 25.2 kW was used to treat bone waste for seven minutes. The bone waste was finally changed into vitric matter and lost 2/3 of its weight after the treatment. The process was highly efficient, economical, convenient, and fuel-free. This method could be used as an alternative for disposal of bone waste, small infectious animals, hazardous hospital waste, etc. 相似文献
98.
Protein isolates from 9 cultivars of peanut (Arachis hypogaea L.) were compared. Sephadex G-200 gel filtration and nondenaturing polyacrylamide gel electrophoresis (NPAGE) of the protein isolates showed very similar patterns of arachin and nonarachin fractions. The content of individual fractions was somewhat different among cultivars, possibly indicating genetic variability. Sodium dodecyl sulfate-PAGE (SDS-PAGE) showed that the protein isolates had extremely complex sub-unit compositions. The content of acidic amino acids of the protein isolates was 34–38%, basic was 15–17%. Differences in some functionalities such as solubility and emulsification activity were conspicuous among cultivars. 相似文献
99.
A fundamental rheological method was used to study the freeze-thaw stability of hydroxypropyl potato starch pastes. The effect of the number of freeze-thaw cycles on the changes in complex modulus (G*) and phase angle (δ) during heating of the thawed starch pastes was evaluated by comparing the rheological measurements with the measurements of syneresis at different centrifugal forces. The centrifugal forces influenced the detection of the first syneresis as well as the extent of syneresis, with regard to the number of freeze-thaw cycles. When starch pastes exhibited syneresis, the G* formed a distinctive peak during heating at 52.5–53.8C. The magnitude of the peak became bigger with number of freeze-thaw cycles. Furthermore, the results of this rheological method give information on the destabilization process and provide a simple method for detection and prediction of the extent of freeze-thaw stability of starch paste. With this method, the effect of the storage period at –20C, and the freezing rate, on the extent of freeze-damage of starch pastes could be investigated successfully. 相似文献
100.
This paper is a study on modal model method in estimating system inputs from vibration responses, which is one of the indirect input identification methods in frequency domain. The method has advantages over the direct inverse method especially when points of operational inputs are inaccessible for artificial excitation but accessible for response measurement. Systematic procedures of an extended modal model method are proposed and checked by numerical experiments. Mechanisms of error propagation, i.e. how errors in modal parameters such as poles and mode shape vectors affect estimation of the input forces, are illustrated. Then, in order to counteract the error propagation, discrete modal filter approach is used in this paper to compute the inversion of modal matrix in which most serious errors seem to be generated. Further, a reduced form of modified reciprocal modal vector (MRMV) is proposed to estimate multiple inputs, which is shown to have orthogonality errors smaller than by the MRMV filter. 相似文献