全文获取类型
收费全文 | 56534篇 |
免费 | 2903篇 |
国内免费 | 189篇 |
专业分类
电工技术 | 816篇 |
综合类 | 78篇 |
化学工业 | 12006篇 |
金属工艺 | 2284篇 |
机械仪表 | 3488篇 |
建筑科学 | 1307篇 |
矿业工程 | 28篇 |
能源动力 | 2410篇 |
轻工业 | 4400篇 |
水利工程 | 298篇 |
石油天然气 | 93篇 |
武器工业 | 2篇 |
无线电 | 9095篇 |
一般工业技术 | 11963篇 |
冶金工业 | 4645篇 |
原子能技术 | 720篇 |
自动化技术 | 5993篇 |
出版年
2024年 | 56篇 |
2023年 | 619篇 |
2022年 | 965篇 |
2021年 | 1634篇 |
2020年 | 1178篇 |
2019年 | 1296篇 |
2018年 | 1617篇 |
2017年 | 1552篇 |
2016年 | 1960篇 |
2015年 | 1462篇 |
2014年 | 2347篇 |
2013年 | 3478篇 |
2012年 | 3589篇 |
2011年 | 4347篇 |
2010年 | 3165篇 |
2009年 | 3309篇 |
2008年 | 3184篇 |
2007年 | 2499篇 |
2006年 | 2318篇 |
2005年 | 1966篇 |
2004年 | 1804篇 |
2003年 | 1710篇 |
2002年 | 1511篇 |
2001年 | 1297篇 |
2000年 | 1148篇 |
1999年 | 1101篇 |
1998年 | 1846篇 |
1997年 | 1205篇 |
1996年 | 966篇 |
1995年 | 676篇 |
1994年 | 569篇 |
1993年 | 480篇 |
1992年 | 345篇 |
1991年 | 326篇 |
1990年 | 314篇 |
1989年 | 292篇 |
1988年 | 238篇 |
1987年 | 209篇 |
1986年 | 166篇 |
1985年 | 146篇 |
1984年 | 114篇 |
1983年 | 91篇 |
1982年 | 46篇 |
1981年 | 59篇 |
1980年 | 49篇 |
1979年 | 42篇 |
1978年 | 43篇 |
1977年 | 56篇 |
1976年 | 86篇 |
1975年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Jae-Chul Lee Ho-In Lee Gyeung-Ho Kim Jung-Ill Lee 《Metallurgical and Materials Transactions A》1997,28(5):1251-1259
Interfacial reactions in the squeeze-cast SAE 329 Al alloy reinforced with SAFFIL and carbon fibers were investigated using
scanning and transmission electron microscopy and secondary ion mass spectroscopy. The SiO2 layer added as a binder for the preform of SAFFIL fiber appeared to prevent excessive reaction between the fiber and the
molten Al alloy during casting. In the as-cast composite, the reaction between the SiO2 layer and the Al alloy is considered to produce MgO crystals in the vicinity of SAFFIL fiber. With subsequent heat treatment
of the composite to the T6 condition, small crystals of MgO and MgAl2O4 were found to form at the surface of SAFFIL fiber as a result of interfacial reaction between the SiO2 layer and the Al alloy. Even at the T6 condition, significant reactions between the Al alloy and SAFFIL fiber itself were
not observed, indicating the effective role of the binder layer in suppressing the degradation of SAFFIL fiber by reaction
with the Al alloy. 相似文献
22.
Flexible manufacturing systems (FMSs) are able to process a wide variety of operations, but the specific mix of operations that can be performed at any point in time depends upon the combination of tools loaded onto the machines. The machines have tool magazines with finite capacities. We consider the problem of assigning operations and their associated tools to machines (or groups of machines) to maximize the throughput for a specified steady-state mix of orders. Since this objective is difficult to deal with directly, we use an intermediate objective of meeting workload targets for each machine group as closely as possible. A certain form of this intermediate objective has been shown to correlate highly with the original objective.
Since it is computationally intractable to find optimal solutions for problems with more than 20 operations, fast heuristic algorithms are developed. These algorithms are adapted from multi-dimensional bin-packing algorithms. Computational results are reported. 相似文献
Since it is computationally intractable to find optimal solutions for problems with more than 20 operations, fast heuristic algorithms are developed. These algorithms are adapted from multi-dimensional bin-packing algorithms. Computational results are reported. 相似文献
23.
24.
Naturally occurring UV active compounds, commonly present in almost all source waters, can be rapidly monitored by their ultraviolet absorbance at 260 nm (E260). Herein, the extent of correlation between the E260 and the removal efficiency of the hazardous contaminants, endocrine disrupters and dioxins, were investigated using various treatment and river source waters. The detection of various types of hazardous contaminants using sophisticated analytical methods, such as high resolution gas chromatography (HRGC)/high resolution mass spectrometry (HRMS) and high performance liquid chromatography (HPLC)/inductively coupled plasma (ICP)/mass spectrometry (MS), as well as various short-term bioassays, can require hours or even days for results to be obtained. The removal of the E260 correlated well with those of individual contaminants, such as endocrine disruptor chemicals and dioxins, with the various treatment processes employed. In the plots of the endocrine disrupters against the DOC/E260, a correlation was found with the endocrine activity of the Korean/Japanese river waters employed in this study. 相似文献
25.
Watson B. Kim J. Moher T. Hindo C. Mceneany T. Gomez L.M. Fransen S. 《Potentials, IEEE》2005,24(2):42-46
The StoryGrid project undertook studying the role new interface technologies might play in education, particularly at the high school level. Unfortunately, technology often seizes center stage in high school classrooms; i.e., it becomes the topic of instruction. We believe that learning about technology would be most successful when technology is not the topic, but simply a tool used during instruction. StoryGrid, therefore, was designed to support and to enhance existing narrative activity in classrooms by adhering to the following goals: trigger reflection and interpretation, accommodate individual expression and encourage student discourse. 相似文献
26.
Amit Chourasia Steve Cutchin Yifeng Cui Reagan W Moore Kim Olsen Steven M Day J Bernard Minster Philip Maechling Thomas H Jordan 《Computer Graphics and Applications, IEEE》2007,27(5):28-34
This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries. 相似文献
27.
Sankaralingam K. Nagarajan R. Haiming Liu Changkyu Kim Jaehyuk Huh Burger D. Keckler S.W. Moore C. 《Micro, IEEE》2003,23(6):46-51
The Tera-op reliable intelligently adaptive processing system (TRIPS) architecture seeks to deliver system-level configurability to applications and runtime systems. It does so by employing the concept of polymorphism, which permits the runtime system to configure the hardware execution resources to match the mode of execution and demands of the compiler and application. 相似文献
28.
Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under different molecular weight of polymer species [polyethylene glycol (PEG) ] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol (PEG)]. The properties of as-prepared ormosil sol such as,viscosity, gelation time were characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its micro-structure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross-flow apparatus. The ormosil sol coated Membrane is easily formed by steric effect of polymer and it improves flux efficiency because infiltration into porous support decreased. Its flux efficiency is elevated about 200(1/m2·h) compared with colloidal sol coated membrane at point of five minutes from starting test. 相似文献
29.
Hordon Kim 《电子与电脑》2006,(5):107
发光聚合物P-OLED开发领导厂商并将P-OLED广泛应用在电子显示器产品上的剑桥显示技术公司(CDT),是一家于1992年在英国成立,以发展、制造并销售P-OLED材料与IP给显示器产业的公司。P-OLED隶属于有机发光二极管的一部份,是一种质地薄、重量轻且具功率效益的组件,当电流流过时就会发光。相较于其它平面显示器技术,如液晶显示器,它们提供更为强化的视觉体验与卓越的效能特性。在技术方面,2005年计有9家获授权公司给付权利金,授权金额总计达到420万美元。这些授权的客户包括Epson在内,Epson最近才发表一项使用OLED做为高亮度的光源,… 相似文献
30.
Jae-Duk Lee Jeong-Hyuk Choi Donggun Park Kinam Kim 《Electron Device Letters, IEEE》2003,24(12):748-750
In contrast to the conventional theories, we have revealed that the most distinguished mechanism in the data retention phenomenon after Fowler-Nordheim (FN) stress in sub-100 nm NAND Flash memory cells is the annihilation of interface states. Interface state generation rate increases rapidly as the channel width of NAND flash cell decreases. Comparison of interface states and stress-induced leakage current (SILC) component during retention mode shows that the annihilation of interface states strongly affects data retention characteristics of the programmed cells. 相似文献