全文获取类型
收费全文 | 7470篇 |
免费 | 475篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 120篇 |
综合类 | 32篇 |
化学工业 | 2018篇 |
金属工艺 | 200篇 |
机械仪表 | 169篇 |
建筑科学 | 467篇 |
矿业工程 | 42篇 |
能源动力 | 256篇 |
轻工业 | 522篇 |
水利工程 | 44篇 |
石油天然气 | 5篇 |
无线电 | 651篇 |
一般工业技术 | 1587篇 |
冶金工业 | 379篇 |
原子能技术 | 52篇 |
自动化技术 | 1410篇 |
出版年
2024年 | 10篇 |
2023年 | 101篇 |
2022年 | 104篇 |
2021年 | 279篇 |
2020年 | 199篇 |
2019年 | 203篇 |
2018年 | 202篇 |
2017年 | 201篇 |
2016年 | 296篇 |
2015年 | 313篇 |
2014年 | 365篇 |
2013年 | 531篇 |
2012年 | 505篇 |
2011年 | 661篇 |
2010年 | 430篇 |
2009年 | 437篇 |
2008年 | 435篇 |
2007年 | 387篇 |
2006年 | 302篇 |
2005年 | 286篇 |
2004年 | 208篇 |
2003年 | 171篇 |
2002年 | 168篇 |
2001年 | 84篇 |
2000年 | 130篇 |
1999年 | 102篇 |
1998年 | 111篇 |
1997年 | 113篇 |
1996年 | 100篇 |
1995年 | 64篇 |
1994年 | 58篇 |
1993年 | 62篇 |
1992年 | 53篇 |
1991年 | 40篇 |
1990年 | 25篇 |
1989年 | 13篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有7954条查询结果,搜索用时 15 毫秒
31.
Head and eye movements were simultaneously recorded during locomotory and pecking behavior of 4 pigeons, which were trained to traverse a conditioning chamber, with a pecking key and a food dispenser at each end. Each trial involved key pecking, walking, and feeding. Head movements were registered with a skull-mounted miniature accelerometer, and eye movements were recorded with implanted electrooculogram (EOG) electrodes. An almost perfect temporal coordination between head and eye movements was observed during both walking and feeding bouts. During walking, head movements primarily provide retinal image stability, and eye movements support visual scanning. During feeding, head movements mainly subserve the grasping of food items, and eye movements maintain visual fixation on them. Because the eyes are reflexively closed during the middle phase of pecks, the head and eye movements are then under ballistic control. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
33.
Nichols M.A. Siegel H.J. Dietz H.G. Quong R.W. Nation W.G. 《Parallel and Distributed Systems, IEEE Transactions on》1991,2(3):290-303
Efficient data layout is an important aspect of the compilation process. A model for the creation of perfect memory maps for large-scale parallel machines capable of user-controlled partitionable single-instruction-multiple data/single-program-multiple data (SIMD/SPMD) operation is developed. The term perfect implies that no memory fragmentation occurs and ensures that the memory map size is kept to a minimum. A major constraint on solving this problem is based on the single program nature of both the SIMD and SPMD modes of parallelism. It is assumed that all processors within the same submachine used identical addresses to access corresponding data items in each of their local memories. Necessary and sufficient conditions are derived for being able to create perfect memory maps, and results are applied to several partitionable interconnection networks 相似文献
34.
A three-phase model for mixed columnar-equiaxed solidification 总被引:1,自引:0,他引:1
A three-phase model for mixed columnar-equiaxed solidification is presented in this article. The three phases are the parent
melt as the primary phase, as well as the solidifying columnar dendrites and globular equiaxed grains as two different secondary
phases. With an Eulerian approach, the three phases are considered as spatially coupled and interpenetrating continua. The
conservation equations of mass, momentum, species, and enthalpy are solved for all three phases. An additional conservation
equation for the number density of the equiaxed grains is defined and solved. Nucleation of the equiaxed grains, diffusion-controlled
growth of both columnar and equiaxed phases, interphase exchanges, and interactions such as mass transfer during solidification,
drag force, solute partitioning at the liquid/solid interface, and release of latent heat are taken into account. Binary steel
ingots (Fe-0.34 wt pct C) with two-dimensional (2-D) axis symmetrical and three-dimensional (3-D) geometries as a benchmark
were simulated. It is demonstrated that the model can be used to simulate the mixed columnar-equiaxed solidification, including
melt convection and grain sedimentation, macrosegregation, columnar-to-equiaxed-transition (CET), and macrostructure distribution.
The model was evaluated by comparing it to classical analytical models based on limited one-dimensional (1-D) cases. Satisfactory
results were obtained. It is also shown that in order to apply this model for industrial castings, further improvements are
still necessary concerning some details. 相似文献
35.
Uwe Kruger David Antory Juergen Hahn George W. Irwin Geoff McCullough 《Computers & Chemical Engineering》2005,29(11-12):2355
Although principal component analysis (PCA) is an important tool in standard multivariate data analysis, little interest has been devoted to assessing whether the underlying relationship within a given variable set can be described by a linear PCA model or whether nonlinear PCA must be utilized. This paper addresses this deficiency by introducing a nonlinearity measure for principal component models. The measure is based on the following two principles: (i) the range of recorded process operation is divided into smaller regions; and (ii) accuracy bounds are determined for the sum of the discarded eigenvalues. If this sum is within the accuracy bounds for each region, the process is assumed to be linear and vice versa. This procedure is automated through the use of cross-validation. Finally, the paper shows the utility of the new nonlinearity measure using two simulation studies and with data from an industrial melter process. 相似文献
36.
37.
Juergen Hartung 《中国集成电路》2007,16(6):44-48
第1部分射频系统级封装(RF SiP,RF System-in-Pack-age)技术是一种对无线通信非常有用的封装平台,无线通信被如下事实所困,但由于目前SiP设计仍 相似文献
38.
A new prediction method with an interior light sensor for the workplane illuminance in daylighting control systems is introduced. Based on radiosity theory, the spatial distributions of daylight and electric light in the space are discussed and the prediction method is developed. An experimental verification of the technique is performed in an outdoor test-room for a double-glazed window system with a motorized venetian blind integrated between the two glazings. Electric light and daylight predictions were performed in accordance with the proposed method. The results showed that the electric light workplane illuminance can be predicted with high accuracy (±5 lux error with a linear correlation) and that the daylight workplane illuminance can be predicted within ±20 lux (with a linear correlation) for any sky conditions (overcast, clear sky, or variable) with the window system controlled to prevent direct daylight transmission. This method is useful for integrated control of motorized daylighting devices and dimmable electric lights. 相似文献
39.
Andreas Karageorghis 《Journal of scientific computing》1991,6(1):21-26
The way boundary conditions are imposed when applying Chebyshev collocation methods to Poisson and biharmonic-type problems in rectangular domains is investigated. It is shown that careful selection of the number of collocation points leads to a linear system ofn linearly independent equations inn unknowns. 相似文献
40.
Zusammenfassung Dieser Artikel beschreibt einige Erfahrungen und typische Problemstellungen mit Textmining in der Medizin und gibt einen Einblick
in aktuelle und zukünftige Herausforderungen in Forschung & Entwicklung. Interessant ist n?mlich, dass auch im ,,Multimedia-Zeitalter“
die meiste Information immer noch als ,,Text“ vorliegt. Mithilfe von statistischen und linguistischen Verfahren wird mit sogenannter
,,Textmining-Software“ versucht, aus Freitexten Information ,,heraus zu schürfen“ (deshalb ,,Textmining“). Allerdings ist
es damit noch nicht genug. Der n?chste Schritt besteht darin, die Information sowohl nutzbar als auch brauchbar zu machen.
Die jeweiligen End-Benutzerinnen und End-Benutzer müssen in die Lage versetzt werden, auf der Basis der gewonnenen Information
deren Wissen zu erweitern. In unserem konkreten Fall sollen damit Entscheidungen im Rahmen ?rztlichen Handelns unterstützt
werden. Probleml?sungen in diesem Bereich erfordern eine holistische Sicht- und Herangehensweise. Daher wird es immer wichtiger,
Erkenntnisse aus Informatik und Psychologie zusammenflie?en zu lassen und auf systemischer Ebene technologisch umzusetzen. 相似文献