全文获取类型
收费全文 | 2010篇 |
免费 | 134篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 37篇 |
综合类 | 4篇 |
化学工业 | 494篇 |
金属工艺 | 72篇 |
机械仪表 | 105篇 |
建筑科学 | 29篇 |
能源动力 | 64篇 |
轻工业 | 204篇 |
水利工程 | 6篇 |
无线电 | 383篇 |
一般工业技术 | 404篇 |
冶金工业 | 131篇 |
原子能技术 | 25篇 |
自动化技术 | 195篇 |
出版年
2024年 | 4篇 |
2023年 | 34篇 |
2022年 | 57篇 |
2021年 | 75篇 |
2020年 | 61篇 |
2019年 | 74篇 |
2018年 | 64篇 |
2017年 | 69篇 |
2016年 | 77篇 |
2015年 | 59篇 |
2014年 | 87篇 |
2013年 | 132篇 |
2012年 | 128篇 |
2011年 | 151篇 |
2010年 | 111篇 |
2009年 | 105篇 |
2008年 | 109篇 |
2007年 | 79篇 |
2006年 | 83篇 |
2005年 | 72篇 |
2004年 | 63篇 |
2003年 | 50篇 |
2002年 | 61篇 |
2001年 | 51篇 |
2000年 | 44篇 |
1999年 | 42篇 |
1998年 | 60篇 |
1997年 | 40篇 |
1996年 | 23篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1976年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有2153条查询结果,搜索用时 31 毫秒
991.
Kyung Tae Park Jun-Hyung Ryu Ho-Kyung Lee In-Beum Lee 《Korean Journal of Chemical Engineering》2013,30(2):278-285
This paper presents a heuristic algorithm for a two-dimensional two-stage guillotine cutting problem with multiple stock sizes by allowing the rotation of items by 90°. The proposed algorithm generates levels or strips where the first item or base item is selected according to the length of the strip and packs the next items beside the base item in the strip. For each type of item, strips are generated for packing each type of item in a base item. The best n orders in a yield of strips or the best n strips are selected for each type of item. The selected best n strips are packed in one type of bin. For the other types of bins, another best n strips are selected and packed in each type of bin. The best yield in all types of bins is then selected. This iteration is executed until the number of item demands in the overall demands is less than the number of item demands in the bin. Four numerical examples generated from actual industries are illustrated to highlight the applicability of the proposed algorithm with some comments. 相似文献
992.
Kang Kyong-Hwa Qian Zhong-Ji Ryu BoMi Kim Se-Kwon 《Food science and biotechnology》2011,20(1):183-191
Microalgae are major primary producers of organic matters in aquatic environments through their photosynthetic activities.
Benthic diatom Navicula incerta is the major component of phytoplankton and also relatively easy to cultivate, used as live food source in aquaculture. The
growth characteristics of N. incerta were estimated under combinations of temperature, salinity, and light; and also its composition and antioxidant activities
were determined. The maximum cell density of 87×105cells/mL, was reached at 20°C, 250 μmol/m2·sec, 33‰ salinity, pH 8.3, 12:12 light:dark, and F/2 medium on 2 weeks of the culture period. The antioxidant enzymatic hydrolysates
efficiently quenched different free radicals: 1,1-diphenyl-2-pycryl-hydrazyl (DPPH) (pepsin IC50=196.0 μg/mL), hydroxyl (α-chymotrypsin IC50=102.0 μg/mL), and superoxide (neutrase IC50=169.0 μg/mL). These results suggest that the enzymatic hydrolysate from N. incerta acts as a candidate against antioxidant and could be used as a potential functional food ingredient. 相似文献
993.
Lee Jae-In Kim Dong Wook Jang Gwang-Ju Song Seonghwa Park Kee Jai Lim Jeong Ho Kim Bo-Min Lee Hyeon-Jeong Chen Feng Ryu Young Bae Kim Hyun-Jin 《Food science and biotechnology》2019,28(3):623-631
Food Science and Biotechnology - Microbial populations in white rice (Oryza sativa L.) samples stored for 6 months in open or closed conditions were studied and their metabolite profiles... 相似文献
994.
For their timely response to the rapidly changing manufacturing environment and markets, future manufacturing systems must be flexible, adaptable, and reusable. Recently, bionic (or biological), holonic, and fractal manufacturing systems (FrMS) have been discussed as potential candidates for the next generation of manufacturing systems. This study focuses on the FrMS, which is based on the concept of autonomous cooperating agents referred to as fractals. The major component of the FrMS is a basic fractal unit (BFU). It consists of five functional modules: observing module (observer), analysing module (analyser), resolving and executing module (resolver), organizing module (organizer), and reporting module (reporter). Although the FrMS has many conceptual advantages, the implementation of the system has been known to be difficult. This paper is a preliminary study of the basic components and the architecture with an eye toward the future implementation of FrMS. In order to describe the characteristics of a fractal, this paper presents several models including function models using IDEF0, working models using Petri-net, and static/dynamic models using the unified modelling language (UML). 相似文献
995.
996.
997.
Md Rokon Ud Dowla Biswas Sangil Hyun Sung-Soo Ryu Dang-Hyok Yoon 《Journal of the European Ceramic Society》2021,41(8):4558-4566
This study examined the compaction behavior of a green ceramic component with a complex shape formed by die pressing at 50 MPa using spray-dried alumina. Compared to a simple cylindrical sample, the sample with a complex shape revealed a higher degree of microstructural inhomogeneity and crack formation. Granule deformation and pore distribution at different sample locations were observed by optical microscopy after infiltrating liquid into the voids of a green compact. The refractive index of the immersion liquid should be different slightly from that of alumina for better observations. X-ray micro-computed tomography was also used to visualize the pore distribution and crack shape. Numerical simulations based on the Drucker-Prager/Cap model were performed to distinguish the stress and displacement distribution within the compact. The significant stress gradient at the crack initiation point could explain crack formation, whereas the application of a higher pressure resulted in a further increase in stress gradient. 相似文献
998.
Bang Hyo Jung Le Thi Giang Kim Joo Yong Ryu Hyung Ki Yoon Kee Bong 《Journal of Mechanical Science and Technology》2021,35(9):3793-3801
Journal of Mechanical Science and Technology - Life assessment predictions of reformer tubes of HP40Nb grade steel used in the petrochemical industry were investigated by quantitative... 相似文献
999.
1000.
Keungarp Ryu Huahua Xue Junghee Park 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2013,88(5):788-793
BACKGROUND: Recently, various composites of carbon nanomaterials and conducting polymers have been actively investigated as potential electrode materials for supercapacitors which can store and deliver large amounts of electrical energy promptly. Harsh chemical or complex electrodeposition methods have been studied to prepare such composites. In this report, the mild and simple enzymatic catalysis of horseradish peroxidase (EC 1.11.1.7) in aqueous solutions (pH 4.0) was utilized for the first time to prepare composites of multiwalled carbon nanotubes and polypyrrole. RESULTS: Electron micrographs show that in situ enzymatic reaction by horseradish peroxidase enables the uniform coating of multiwalled carbon nanotubes with polypyrrole without containing the polymer aggregates. The specific capacitance of the composites (46.2 F g?1) measured with a two‐electrode cell containing an electrolyte of 1 mol L?1 NaNO3 increased more than four‐fold compared with that obtained with bare multiwalled carbon nanotubes (10.8 F g?1). CONCLUSIONS: Horseradish peroxidase‐catalyzed in situ synthesis of the composites of multiwalled carbon nanotubes and polypyrrole requires neither the derivatization of multiwalled carbon nanotubes and/or pyrrole monomers nor the post‐doping of the synthesized composites to enhance the capacitance of the composites. © 2012 Society of Chemical Industry 相似文献