全文获取类型
收费全文 | 4223篇 |
免费 | 260篇 |
国内免费 | 38篇 |
专业分类
电工技术 | 63篇 |
综合类 | 68篇 |
化学工业 | 917篇 |
金属工艺 | 179篇 |
机械仪表 | 171篇 |
建筑科学 | 222篇 |
矿业工程 | 42篇 |
能源动力 | 293篇 |
轻工业 | 559篇 |
水利工程 | 25篇 |
石油天然气 | 39篇 |
武器工业 | 2篇 |
无线电 | 252篇 |
一般工业技术 | 650篇 |
冶金工业 | 382篇 |
原子能技术 | 54篇 |
自动化技术 | 603篇 |
出版年
2024年 | 24篇 |
2023年 | 45篇 |
2022年 | 93篇 |
2021年 | 134篇 |
2020年 | 161篇 |
2019年 | 144篇 |
2018年 | 195篇 |
2017年 | 171篇 |
2016年 | 206篇 |
2015年 | 110篇 |
2014年 | 195篇 |
2013年 | 440篇 |
2012年 | 223篇 |
2011年 | 249篇 |
2010年 | 195篇 |
2009年 | 247篇 |
2008年 | 195篇 |
2007年 | 167篇 |
2006年 | 136篇 |
2005年 | 90篇 |
2004年 | 96篇 |
2003年 | 119篇 |
2002年 | 165篇 |
2001年 | 126篇 |
2000年 | 68篇 |
1999年 | 55篇 |
1998年 | 133篇 |
1997年 | 71篇 |
1996年 | 57篇 |
1995年 | 29篇 |
1994年 | 30篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 12篇 |
1982年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1973年 | 2篇 |
1965年 | 3篇 |
排序方式: 共有4521条查询结果,搜索用时 15 毫秒
41.
42.
43.
Effect of sodium monofluorophosphate treatment on microstructure and frost salt scaling durability of slag cement paste 总被引:1,自引:0,他引:1
Sodium-monofluorophosphate (Na-MFP) is currently in use as a surface applied corrosion inhibitor in the concrete industry. Its basic mechanism is to protect the passive layer of the reinforcement steel against disruption due to carbonation. Carbonation is known as the most detrimental environmental effect on blast furnace slag cement (BFSC) concrete with respect to frost salt scaling. In this paper the effect of Na-MFP on the microstructure and frost salt scaling resistance of carbonated BFSC paste is presented. The results of electron microscopy, mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD) are discussed. It is found that the treatment modifies the microstructure and improves the resistance of carbonated BFSC paste against frost salt attack. 相似文献
44.
Because of the variety of climate conditions very different oil plants except of some tropical kinds grow in Turkey. In this work four groups of raw material of Turkish vegetable oils were investigated. The first group consists of olive, sunflower and cotton, which are important raw materials in Turkey. About 97% of the oil produced in Turkey base on these three raw materials. The second group consists of sesame, poppy, linseed, hemp-seed, rape, soyabean, safflower, castor bean and groundnut, which are temporary of lower importance for Turkey. The third group consists of the non-traditional oil raw materials like tobacco seed, grape seed, scabious, fig seed, tomato seed, laurel seed, pistacia terebinthus, rice bran, maize germs, anise seed, peach-stones and pumpkin seed. The fourth group consists of fruits rich in oil like hazel-nuts, walnuts, almonds and pistachio-nuts, whose production is of great importance in Turkey. 相似文献
45.
This paper is the first one of the two papers entitled “modeling and solving mixed-model assembly line balancing problem with setups”, which has the aim of developing the mathematical programming formulation of the problem and solving it with a hybrid meta-heuristic approach. In this current part, a mixed-integer linear mathematical programming (MILP) model for mixed-model assembly line balancing problem with setups is developed. The proposed MILP model considers some particular features of the real world problems such as parallel workstations, zoning constraints, and sequence dependent setup times between tasks, which is an actual framework in assembly line balancing problems. The main endeavor of Part-I is to formulate the sequence dependent setup times between tasks in type-I mixed-model assembly line balancing problem. The proposed model considers the setups between the tasks of the same model and the setups because of the model switches in any workstation. The capability of our MILP is tested through a set of computational experiments. Part-II tackles the problem with a multiple colony hybrid bees algorithm. A set of computational experiments is also carried out for the proposed approach in Part-II. 相似文献
46.
Alper Sarıoğlan Ömer Tunç Savaşçı Ayşe Erdem-Şenatalar Vu Thu Ha Gilbert Sapaly Younès Ben Taârit 《Catalysis Letters》2007,118(1-2):123-128
MFI type inorganic carrier was used in two different cationic forms, hydrogen and calcium respectively. MFI-supported molybdenum
and rhenium catalysts were prepared. The activities of the catalysts were compared for the aromatization reaction of methane.
Higher activity values were attained with the catalysts supported on HZSM-5. Aromatics were also observed with the catalysts
supported on CaZSM-5, despite their deficiency in acid sites. Highly dispersed rhenium is expected to be formed with the use
of the inorganic carrier in calcium form. On the other hand, lower reaction rates were observed with rhenium supported on
CaZSM-5, in spite of the improved dispersion of the active rhenium species on this catalyst. This was interpreted in terms
of the critical role of the acid sites in the conversion of methane to aromatics, compared to the improved dispersion of the
active metal. 相似文献
47.
SRAM-based pipelined architectures for high-speed IP lookup using Field Programmable Gate Arrays (FPGAs) has recently attracted a great deal of attention from researchers. Due to the limited amount of on-chip memory and the number of I/O pins of FPGAs, compact data structures providing high memory efficiency are in great demand. 相似文献
48.
Virtualisation and cloud computing have recently received significant attention. Resource allocation and control of multiple resource usages among virtual machines in virtualised data centres remains an open problem. Therefore, in this paper, our focus is to control CPU (central processing unit) usage and memory consumption of a virtual database machine in a data centre under a time-varying heavy workload. In addition to existing work, we attempt to control multiple outputs, such as the CPU usage and memory consumption of a virtualised database server (DBVM), via changing multiple server parameters, such as the CPU allocation and memory allocation, in real time. We indicated that a virtualised database server might be modelled as a linear time-unvarying system. We obtained and compared both MIMO (multi input–multi output) and multiple SISO (single input–single output) models of that system. We designed multiple SISO feedback controllers to achieve desired CPU usages and memory consumptions under workload. 相似文献
49.
50.
Summary Swelling equilibrium of polyelectrolyte copolymer gels containing of acrylamide (AAm) and 2-acrylamido-2-methyl-1-propanesulfonic
acid sodium salt (AMPS) have been studied as a function of copolymer composition. AAm/AMPS hydrogels were prepared by free
radical solution polymerization in aqueous solution of AAm with AMPS as anionic comonomer and two multifunctional crosslinkers
such as ethylene glycol dimethacrylate (EGDMA) and trimethylolpropane triacrylate (TMPTA). Swelling experiments were performed
in water at 25 °C, gravimetrically. The influence of AMPS content in hydrogels was examined. Swelling of AAm/AMPS hydrogels
was increased up to 1018% (for containing 2% AMPS and crosslinked by EGDMA) 15246% (for containing 8% AMPS and crosslinked
by TMPTA), while AAm hydrogels swelled up to 804% (crosslinked by TMPTA)–770% (crosslinked by EGDMA). The values of equilibrium
water content of the hydrogels are 0.8851–0.9935. Diffusion behavior was investigated. Water diffusion into hydrogels was
found to be non-Fickian in character. 相似文献