全文获取类型
收费全文 | 1595篇 |
免费 | 50篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 480篇 |
金属工艺 | 32篇 |
机械仪表 | 9篇 |
建筑科学 | 63篇 |
矿业工程 | 2篇 |
能源动力 | 32篇 |
轻工业 | 172篇 |
水利工程 | 10篇 |
石油天然气 | 8篇 |
无线电 | 166篇 |
一般工业技术 | 297篇 |
冶金工业 | 144篇 |
原子能技术 | 13篇 |
自动化技术 | 213篇 |
出版年
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 10篇 |
2019年 | 14篇 |
2018年 | 19篇 |
2017年 | 25篇 |
2016年 | 26篇 |
2015年 | 26篇 |
2014年 | 41篇 |
2013年 | 87篇 |
2012年 | 58篇 |
2011年 | 97篇 |
2010年 | 67篇 |
2009年 | 70篇 |
2008年 | 90篇 |
2007年 | 64篇 |
2006年 | 71篇 |
2005年 | 49篇 |
2004年 | 62篇 |
2003年 | 51篇 |
2002年 | 69篇 |
2001年 | 32篇 |
2000年 | 32篇 |
1999年 | 36篇 |
1998年 | 33篇 |
1997年 | 20篇 |
1996年 | 25篇 |
1995年 | 24篇 |
1994年 | 26篇 |
1993年 | 24篇 |
1992年 | 24篇 |
1991年 | 16篇 |
1990年 | 18篇 |
1989年 | 23篇 |
1988年 | 19篇 |
1987年 | 15篇 |
1986年 | 16篇 |
1985年 | 30篇 |
1984年 | 13篇 |
1983年 | 23篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 15篇 |
1976年 | 16篇 |
1975年 | 20篇 |
1974年 | 10篇 |
1966年 | 7篇 |
排序方式: 共有1655条查询结果,搜索用时 0 毫秒
21.
22.
Mohamed Sahli Christine Millot Claude Roques-Carmes Chantal Khan Malek 《Microsystem Technologies》2009,15(6):827-835
Numerical modelling of the deformation of a polymer using the finite elements method in axisymetrical mode was performed using the LsDyna® software to describe the filling of micro-cavities during the forming process of the material using the hot embossing. These simulations firstly allow verifying whether the chosen forming process conditions promote or not an optimized filling of the superficial cavities in order to achieve precise replicas which best reproduce the superficial topography of the mould. The simulations were carried out to evaluate the filling of the cavities taking into account the mechanical behaviour of the selected polymer into the model. Moreover, these models were developed to verify the effect of the distribution of the mould cavities on their filling. The influence of the mobility of non deformable rigid plates on the filling of the cavities represents an auxiliary variable. In the approach presented, the compression plates are assumed to be parallel and non deformable, whereas the polymer disk follows a rubbery behaviour around a temperature equal to 140°C. Globally the modelling results are satisfactory for they are rather close to the experimental observations conducted. In summary, the effect of the normal stress as also the distribution of micro-cavities at the mould surface seem to prevail in the case of the forming process by hot embossing. 相似文献
23.
Digital microfluidic design and optimization of classic and new fluidic functions for lab on a chip systems 总被引:2,自引:2,他引:0
Yves Fouillet Dorothée Jary Claude Chabrol Patricia Claustre Christine Peponnet 《Microfluidics and nanofluidics》2008,4(3):159-165
This paper deals with microfluidic studies for lab-on-a-chip development. The first goal was to develop microsystems immediately
usable by biologists for complex protocol integrations. All fluid operations are performed on nano-liter droplet independently
handled solely by electrowetting on dielectric (EWOD) actuation. A bottom-up architecture was used for chip design due to
the development and validation of elementary fluidic designs, which are then assembled. This approach speeds up development
and industrialization while minimizing the effort in designing and simplifying chip-fluidic programming. Dispensing reproducibility
for 64 nl droplets obtained a CV below 3% and mixing time was only a few seconds. Ease of the integration was demonstrated
by performing on chip serial dilutions of 2.8-folds, four times. The second part of this paper concerns the development of
new innovative fluidic functions in order to extend EWOD-actuated digital fluidics’ capabilities. Experiments of particle
dispensing by EWOD droplet handling are reported. Finally, work is shown concerning the coupling of EWOD actuation and magnetic
fields for magnetic bead manipulation. 相似文献
24.
We present a suite of programs to determine the ground state of the time-independent Gross-Pitaevskii equation, used in the simulation of Bose-Einstein condensates. The calculation is based on the Optimal Damping Algorithm, ensuring a fast convergence to the true ground state. Versions are given for the one-, two-, and three-dimensional equation, using either a spectral method, well suited for harmonic trapping potentials, or a spatial grid.
Program summary
Program title: GPODACatalogue identifier: ADZN_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZN_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 5339No. of bytes in distributed program, including test data, etc.: 19 426Distribution format: tar.gzProgramming language: Fortran 90Computer: ANY (Compilers under which the program has been tested: Absoft Pro Fortran, The Portland Group Fortran 90/95 compiler, Intel Fortran Compiler)RAM: From <1 MB in 1D to ∼102 MB for a large 3D gridClassification: 2.7, 4.9External routines: LAPACK, BLAS, DFFTPACKNature of problem: The order parameter (or wave function) of a Bose-Einstein condensate (BEC) is obtained, in a mean field approximation, by the Gross-Pitaevskii equation (GPE) [F. Dalfovo, S. Giorgini, L.P. Pitaevskii, S. Stringari, Rev. Mod. Phys. 71 (1999) 463]. The GPE is a nonlinear Schrödinger-like equation, including here a confining potential. The stationary state of a BEC is obtained by finding the ground state of the time-independent GPE, i.e., the order parameter that minimizes the energy. In addition to the standard three-dimensional GPE, tight traps can lead to effective two- or even one-dimensional BECs, so the 2D and 1D GPEs are also considered.Solution method: The ground state of the time-independent of the GPE is calculated using the Optimal Damping Algorithm [E. Cancès, C. Le Bris, Int. J. Quantum Chem. 79 (2000) 82]. Two sets of programs are given, using either a spectral representation of the order parameter [C.M. Dion, E. Cancès, Phys. Rev. E 67 (2003) 046706], suitable for a (quasi) harmonic trapping potential, or by discretizing the order parameter on a spatial grid.Running time: From seconds in 1D to a few hours for large 3D grids 相似文献25.
Nicolas Grégori Jean-Charles Hautecouverture François Charoy Claude Godart 《AI & Society》2006,20(3):384-402
Analyzing the way computer technologies are used is crucial for their development. Such analyses make it possible to evaluate these technologies and enhance their evolution. The present article presents some ideas drawn from the development of a cooperation platform for elementary school children (10–11 years old). On the basis of an obvious ergonomic requirement, we worked on two other dimensions: cultural aspects and the teaching scenario. The goal was to set up observation situations and analyze the conversations produced during those situations, in order to understand what using the platform meant to both the pupils and their teachers.
相似文献
Claude GodartEmail: |
26.
Sreng J Lécuyer A Mégard C Andriot C 《IEEE transactions on visualization and computer graphics》2006,12(5):1013-1020
This paper describes a set of visual cues of contact designed to improve the interactive manipulation of virtual objects in industrial assembly/maintenance simulations. These visual cues display information of proximity, contact and effort between virtual objects when the user manipulates a part inside a digital mock-up. The set of visual cues encloses the apparition of glyphs (arrow, disk, or sphere) when the manipulated object is close or in contact with another part of the virtual environment. Light sources can also be added at the level of contact points. A filtering technique is proposed to decrease the number of glyphs displayed at the same time. Various effects--such as change in color, change in size, and deformation of shape- can be applied to the glyphs as a function of proximity with other objects or amplitude of the contact forces. A preliminary evaluation was conducted to gather the subjective preference of a group of participants during the simulation of an automotive assembly operation. The collected questionnaires showed that participants globally appreciated our visual cues of contact. The changes in color appeared to be preferred concerning the display of distances and proximity information. Size changes and deformation effects appeared to be preferred in terms of perception of contact forces between the parts. Last, light sources were selected to focus the attention of the user on the contact areas. 相似文献
27.
The purpose of this paper is relative to the determination of the multiplication factor Mfor an optimum behaviour of the avalanche photodetector. Two types of avalanche photodetector s are compared: a silicon structure n + πpπp + Read diode and a GaAlAs heterostructure. Calculating the Noise Equivalent Power (nep)of the whole system, the law Si(f) =2q IphoMx is used, where the parameter x is determined experimentally in both avalanche photodetectors. The exponent x (between 2 and 4) dominates in the nep expression and the ideal nep for the avalanche photodetector system is obtained when x equals 2. 相似文献
28.
Abstract Discharge records originating from 78 rivers within the Asia-Pacific region are used to assess a possible relationship between a temporal El Niño-Southern Oscillation (ENSO) Index and regional discharges of rivers. The rivers selected have long monthly discharge series and are geographically distributed throughout the whole region. Analyses of variance are used to identify the sub-regions most teleconnected to the ENSO signal. Composite analyses show the temporal patterns of the relationships between river discharge and the ENSO signal and the possible presence of a time lagged relationship. The analyses show that the rivers of the Oceania-Pacific region are the most affected and that a majority of rivers show a similar temporal pattern, thus allowing the construction of a regional composite streamflow index. The temporal patterns of the identified relationships demonstrate the possibility of forecasting the occurrence of abnormally high or low flows (floods/droughts) months ahead of time. 相似文献
29.