全文获取类型
收费全文 | 86193篇 |
免费 | 13978篇 |
国内免费 | 162篇 |
专业分类
电工技术 | 1425篇 |
综合类 | 71篇 |
化学工业 | 26844篇 |
金属工艺 | 2532篇 |
机械仪表 | 4019篇 |
建筑科学 | 2721篇 |
矿业工程 | 25篇 |
能源动力 | 2902篇 |
轻工业 | 10484篇 |
水利工程 | 550篇 |
石油天然气 | 140篇 |
武器工业 | 2篇 |
无线电 | 13435篇 |
一般工业技术 | 20780篇 |
冶金工业 | 4448篇 |
原子能技术 | 690篇 |
自动化技术 | 9265篇 |
出版年
2024年 | 50篇 |
2023年 | 584篇 |
2022年 | 901篇 |
2021年 | 1701篇 |
2020年 | 2355篇 |
2019年 | 3980篇 |
2018年 | 4230篇 |
2017年 | 4465篇 |
2016年 | 5222篇 |
2015年 | 4835篇 |
2014年 | 5550篇 |
2013年 | 7673篇 |
2012年 | 5787篇 |
2011年 | 6120篇 |
2010年 | 5264篇 |
2009年 | 5278篇 |
2008年 | 4719篇 |
2007年 | 3958篇 |
2006年 | 3584篇 |
2005年 | 3013篇 |
2004年 | 2840篇 |
2003年 | 2763篇 |
2002年 | 2509篇 |
2001年 | 2169篇 |
2000年 | 2021篇 |
1999年 | 1383篇 |
1998年 | 1629篇 |
1997年 | 1054篇 |
1996年 | 836篇 |
1995年 | 582篇 |
1994年 | 498篇 |
1993年 | 429篇 |
1992年 | 310篇 |
1991年 | 294篇 |
1990年 | 275篇 |
1989年 | 248篇 |
1988年 | 215篇 |
1987年 | 179篇 |
1986年 | 135篇 |
1985年 | 122篇 |
1984年 | 98篇 |
1983年 | 71篇 |
1982年 | 39篇 |
1981年 | 40篇 |
1980年 | 35篇 |
1979年 | 32篇 |
1978年 | 33篇 |
1977年 | 41篇 |
1976年 | 64篇 |
1975年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
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
152.
153.
Jong Min Kim Donghee Lee Sang Lyul Min Chong Sang Kim 《Information Processing Letters》2003,85(2):93-97
A new dynamic buffer allocation strategy based on the notion of marginal gains is presented for the buffer cache that is used by the operating system to store frequently accessed disk blocks in main memory, and the performance of the proposed strategy is compared with those of previous allocation strategies. In the proposed strategy, marginal gain values are predicted by exploiting functions that approximate the expected number of buffer hits per unit time. Experimental results from both trace-driven simulation and an actual implementation in the FreeBSD operating system show that the proposed strategy accurately predicts the marginal gain values for various workloads resulting in significantly improved buffer hit ratios. 相似文献
154.
Hyun-Chul Kim Author VitaeDaijin KimAuthor Vitae Sung Yang Bang Author Vitae 《Pattern recognition》2003,36(5):1095-1105
Linear discriminant analysis (LDA) is a data discrimination technique that seeks transformation to maximize the ratio of the between-class scatter and the within-class scatter. While it has been successfully applied to several applications, it has two limitations, both concerning the underfitting problem. First, it fails to discriminate data with complex distributions since all data in each class are assumed to be distributed in the Gaussian manner. Second, it can lose class-wise information, since it produces only one transformation over the entire range of classes. We propose three extensions of LDA to overcome the above problems. The first extension overcomes the first problem by modelling the within-class scatter using a PCA mixture model that can represent more complex distribution. The second extension overcomes the second problem by taking different transformation for each class in order to provide class-wise features. The third extension combines these two modifications by representing each class in terms of the PCA mixture model and taking different transformation for each mixture component. It is shown that all our proposed extensions of LDA outperform LDA concerning classification errors for synthetic data classification, hand-written digit recognition, and alphabet recognition. 相似文献
155.
156.
This paper presents an application of digital signal processing to data acquired by the radio imaging method (RIM) that was adopted to measure moisture distribution inside the human body. RIM was originally developed for the mining industry; we are applying the method to a biomedical measurement because of its simplicity, economy, and safety. When a two‐dimensional image was constructed from the measured data, the method provided insufficient resolution because the wavelength of the measurement medium, a weak electromagnetic wave in a VHF band, was longer than human tissues. We built and measured a phantom, a model simulating the human body, consisting of two water tanks representing large internal organs. A digital equalizer was applied to the measured values as a weight function, and images were reconstructed that corresponded to the original shape of the two water tanks. As a result, a two‐dimensional image containing two individual peaks corresponding to the original two small water tanks was constructed. The result suggests the method was applicable to biomedical measurement by the assistance of digital signal processing. This technique may be applicable to home‐based medical care and other situations in which safety, simplicity, and economy are important. 相似文献
157.
158.
159.
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
160.
Nickel-rich β-NiAl alloys, which are potential materials for high-temperature shape-memory alloys, show a thermoelastic martensitic transformation,
which produces their shape memory effect. However, the transformation to Ni5Al3 phase during heating of NiAl martensite can interrupt the reversible martensitic transformation; consequently, the shape
memory effect in NiAl martensite might not appear after heating. The phase transformation process in binary Ni-(34 to 37)Al
martensite was investigated by differential thermal analysis (DTA) method, and we found that the condition of reversible martensitic
transformation was not the β → Ni5Al3 transformation, but rather the M → Ni5Al3 transformation occurring at 250 °C to 300 °C. Therefore, the transformation temperature of M → Ni5Al3 determined the highest operating temperature for the shape memory effect. For verifying the critical temperature, the phase
transformation process was investigated for eight ternary Ni-33Al-X alloys (X=Cu, Co, Fe, Mn, Cr, Ti, Si, and Nb). Only Ti,
Si, and Nb additions were found to be effective in dropping the M
s temperature, and they facilitated the shape memory effect in Ni-33Al-X alloys. In particular, the addition of Si and Nb raised
the transformation temperature of M → Ni5Al3, a potentially beneficial effect for shape memory at higher temperatures.
This article is based on a presentation made in the symposium entitled “Fundamentals of Structural Intermetallics,” presented
at the 2002 TMS Annual Meeting, February 21–27, 2002, in Seattle, Washington, under the auspices of the ASM and TMS Joint
Committee on Mechanical Behavior of Materials. 相似文献