全文获取类型
收费全文 | 485622篇 |
免费 | 89566篇 |
国内免费 | 56835篇 |
专业分类
电工技术 | 45796篇 |
技术理论 | 35篇 |
综合类 | 41250篇 |
化学工业 | 72650篇 |
金属工艺 | 40846篇 |
机械仪表 | 26145篇 |
建筑科学 | 35675篇 |
矿业工程 | 22557篇 |
能源动力 | 16610篇 |
轻工业 | 39886篇 |
水利工程 | 12949篇 |
石油天然气 | 31099篇 |
武器工业 | 6229篇 |
无线电 | 61930篇 |
一般工业技术 | 63147篇 |
冶金工业 | 22514篇 |
原子能技术 | 4646篇 |
自动化技术 | 88059篇 |
出版年
2024年 | 3833篇 |
2023年 | 8947篇 |
2022年 | 13757篇 |
2021年 | 17808篇 |
2020年 | 17685篇 |
2019年 | 24947篇 |
2018年 | 27367篇 |
2017年 | 29392篇 |
2016年 | 28302篇 |
2015年 | 30696篇 |
2014年 | 32763篇 |
2013年 | 35017篇 |
2012年 | 36146篇 |
2011年 | 34399篇 |
2010年 | 30736篇 |
2009年 | 26828篇 |
2008年 | 24967篇 |
2007年 | 23489篇 |
2006年 | 22678篇 |
2005年 | 19834篇 |
2004年 | 17585篇 |
2003年 | 14349篇 |
2002年 | 13127篇 |
2001年 | 11566篇 |
2000年 | 11460篇 |
1999年 | 11624篇 |
1998年 | 9815篇 |
1997年 | 8381篇 |
1996年 | 7931篇 |
1995年 | 7181篇 |
1994年 | 5883篇 |
1993年 | 4755篇 |
1992年 | 4227篇 |
1991年 | 3124篇 |
1990年 | 2460篇 |
1989年 | 2176篇 |
1988年 | 1645篇 |
1987年 | 696篇 |
1986年 | 569篇 |
1985年 | 411篇 |
1984年 | 282篇 |
1983年 | 214篇 |
1982年 | 261篇 |
1981年 | 231篇 |
1980年 | 168篇 |
1976年 | 270篇 |
1975年 | 216篇 |
1972年 | 242篇 |
1971年 | 138篇 |
1960年 | 206篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
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
94.
95.
96.
Hitoshi Kurokawa Taku Nakayama Yasunori Kobayashi Ken Suzuki Mutsumi Takahashi Seiichi Takami Momoji Kubo Naotsugu Itoh Parasuraman Selvam Akira Miyamoto 《Catalysis Today》2003,82(1-4):233-240
A modified Monte Carlo (MC) simulation was performed to investigate the hydrogen absorption behavior in Pd and Pd–Ag alloys of the composition PdxAg1−x (x=0.7–0.8) under H2 pressure (0.1 MPa) at different temperatures. The present method employed can consider the dissociative adsorption of hydrogen molecule and the subsequent absorption of hydrogen atom by formalizing the relationship between the pressure of hydrogen molecule and hydrogen atom. The potential parameters were determined to reproduce the solution enthalpy of hydrogen in pure metals. The results are in good agreement with experimental findings as well as previous theoretical studies. We confirmed that our method is useful to simulate the absorption of hydrogen in metals and alloys. 相似文献
97.
Sanghoon Lee Chris Podilchuk Vidhya Krishnan Alan C. Bovik 《The Journal of VLSI Signal Processing》2003,34(1-2):149-166
By exploiting new human-machine interface techniques, such as visual eyetrackers, it should be possible to develop more efficient visual multimedia services associated with low bandwidth, dynamic channel adaptation and robust visual data transmission. In this paper, we introduce foveation-based error resilience and unequal error protection techniques over highly error-prone mobile networks. Each frame is spatially divided into foveated and background layers according to perceptual importance. Perceptual importance is determined either through an eye tracker or by manually selecting a region of interest. We attempt to improve reconstructed visual quality by maintaining the high visual source throughput of the foveated layer using foveation-based error resilience and error correction using a combination of turbo codes and ARQ (automatic reQuest). In order to alleviate the degradation of visual quality, a foveation based bitstream partitioning is developed. In an effort to increase the source throughput of the foveated layer, we develop unequal delay-constrained ARQ (automatic reQuest) and rate compatible punctured turbo codes where the punctual pattern of RCPC (rate compatible punctured convolutional) codes in H.223 Annex C is used. In the simulation, the visual quality is significantly increased in the area of interest using foveation-based error resilience and unequal error protection; (as much as 3 dB FPSNR (foveal peak signal to noise ratio) improvement) at 40% packet error rate. Over real-fading statistics measured in the downtown area of Austin, Texas, the visual quality is increased up to 1.5 dB in PSNR and 1.8 dB in FPSNR at a channel SNR of 5 dB. 相似文献
98.
T. B. Massalski W. A. Soffa D. E. Laughlin 《Metallurgical and Materials Transactions A》2006,37(13):825-831
In this article, some views on the nature of incoherent interphase interfaces, and their role in the nucleation and growth
processes governing the evolution of microstructure in solid-state diffusional transformations (reconstructive transformations),
are explored. It is argued that essentially incoherent interfaces can be involved in the initiation and propagation of polymorphic
transformations and massive transformations as well as in various precipitation phenomena in metallic and ceramic systems.
Similar views have already been advanced earlier in connection with studies of massive transformations. Faceting along the
interphase interface during nucleation and growth can derive from thermodynamic, kinetic, and crystallographic factors independent
of the bicrystallography of the conjugate phases. This idiomorphic behavior can be relevant to both intergranular and intragranular
phase formation. The concept of one-dimensional (1-D) commensuration of phases through plane edge-to-edge/row matching is
an interesting extension of the classic ideas of coherency and bicrystallography and potentially important in characterizing
the behavior of certain types of boundaries. However, the general importance of these geometrical relations in real and reciprocal
space will depend on the depth of the energy wells in orientation space associated with these special boundaries.
This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms
of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under
the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee. 相似文献
99.
We have developed and implemented techniques that double the performance of dynamically-typed object-oriented languages. Our SELF implementation runs twice as fast as the fastest Smalltalk implementation, despite SELF's lack of classes and explicit variables.To compensate for the absence of classes, our system uses implementation-levelmaps to transparently group objects cloned from the same prototype, providing data type information and eliminating the apparent space overhead for prototype-based systems. To compensate for dynamic typing, user-defined control structures, and the lack of explicit variables, our system dynamically compilesmultiple versions of a source method, eachcustomized according to its receiver's map. Within each version the type of the receiver is fixed, and thus the compiler can statically bind andinline all messages sent toself.Message splitting andtype prediction extract and preserve even more static type information, allowing the compiler to inline many other messages. Inlining dramatically improves performance and eliminates the need to hard-wire low-level methods such as+, ==, andifTrue:.Despite inlining and other optimizations, our system still supports interactive programming environments. The system traverses internal dependency lists to invalidate all compiled methods affected by a programming change. The debugger reconstructs inlined stack frames from compiler-generated debugging information, making inlining invisible to the SELF programmer.This work has been generously supported by National Science Foundation Presidential Young Investigator Grant #CCR-8657631, and by IBM, Texas Instruments, NCR, Tandem Computers, Apple Computer, and Sun Microsystems.This paper was originally published inOOPSLA '89 Conference Proceedings (SIGPLAN Notices, 25, 10 (1989) 49–70). 相似文献
100.
A peculiar type of preferential orientation was recently observed in polycrystalline films that are formed by a solid-state
reaction on a single crystal substrate. This texture, for which the term axiotaxy was proposed, is characterized by the preferred
alignment of a low-index plane in the film to a low-index plane with the same d-spacing in the substrate. The alignment of
lattice planes with nearly identical d-spacings across the interface results in a periodic structure along one direction in
the plane of the interface. As a consequence of the constraint that a set of planes in the film is preferentially parallel
to a set of planes in the substrate, the texture manifests itself as an off-normal fiber texture.
This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Grwoth Mechanisms
of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under
the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee. 相似文献