全文获取类型
收费全文 | 7923篇 |
免费 | 533篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 134篇 |
综合类 | 18篇 |
化学工业 | 2083篇 |
金属工艺 | 196篇 |
机械仪表 | 211篇 |
建筑科学 | 293篇 |
矿业工程 | 25篇 |
能源动力 | 294篇 |
轻工业 | 1353篇 |
水利工程 | 56篇 |
石油天然气 | 31篇 |
武器工业 | 1篇 |
无线电 | 430篇 |
一般工业技术 | 1765篇 |
冶金工业 | 231篇 |
原子能技术 | 62篇 |
自动化技术 | 1279篇 |
出版年
2023年 | 80篇 |
2022年 | 124篇 |
2021年 | 290篇 |
2020年 | 169篇 |
2019年 | 214篇 |
2018年 | 311篇 |
2017年 | 317篇 |
2016年 | 359篇 |
2015年 | 287篇 |
2014年 | 388篇 |
2013年 | 793篇 |
2012年 | 497篇 |
2011年 | 589篇 |
2010年 | 533篇 |
2009年 | 409篇 |
2008年 | 356篇 |
2007年 | 293篇 |
2006年 | 224篇 |
2005年 | 164篇 |
2004年 | 144篇 |
2003年 | 152篇 |
2002年 | 131篇 |
2001年 | 88篇 |
2000年 | 96篇 |
1999年 | 74篇 |
1998年 | 73篇 |
1997年 | 56篇 |
1996年 | 64篇 |
1995年 | 63篇 |
1994年 | 56篇 |
1993年 | 62篇 |
1992年 | 48篇 |
1991年 | 41篇 |
1990年 | 39篇 |
1989年 | 43篇 |
1988年 | 38篇 |
1986年 | 22篇 |
1985年 | 53篇 |
1984年 | 61篇 |
1983年 | 52篇 |
1982年 | 56篇 |
1981年 | 69篇 |
1980年 | 61篇 |
1979年 | 50篇 |
1978年 | 47篇 |
1977年 | 36篇 |
1976年 | 48篇 |
1975年 | 37篇 |
1974年 | 24篇 |
1973年 | 39篇 |
排序方式: 共有8462条查询结果,搜索用时 343 毫秒
141.
The interaction spaces between instructors and learners in the traditional face-to-face classroom environment are being changed by the diffusion and adoption of many forms of computer-based pedagogy. An integrated understanding of these evolving interaction spaces together with how they interconnect and leverage learning are needed to develop meaningful strategies for effective teaching and learning. The 18i collaborative interaction spaces model was designed based on constructivist principles, and describes 18 mixed instructor–learner spaces contextualized at a finer operational scale that makes explicit a wider range of interactions. The model was implemented during the life cycle of an undergraduate GIS-based multimedia cartography course. One output was the generation of a repository of rule-based trajectory plans for rapid planning and problem solving. The model provides an integrated workflow to manage course contents, products, interactions, individuality, and learning styles in blended environments. 相似文献
142.
Roman Frič 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2009,13(1):63-70
We deal with categorical aspects of the extensions of generalized probability measures. In particular, we study various domains
of fuzzy sets, describe the relationships between σ-fields of crisp sets and generated Łukasiewicz tribes of measurable functions, and mention some probabilistic aspects. D-posets and sequential continuity play an important role.
This work was supported by the Slovak Research and Development Agency under the contract No. APVV-0071-06, Protocol for Scientific
and Technological Collaboration between the Republic of Italy and Slovak Republic, Project No. 15: Algebraic and Logical Systems
of Soft Computing, and VEGA 2/6088/26. 相似文献
143.
144.
Mick Donegan Jeffrey D. Morris Fulvio Corno Isabella Signorile Adriano Chió Valentina Pasian Alessandro Vignola Margret Buchholz Eva Holmqvist 《Universal Access in the Information Society》2009,8(4):259-275
Gaze-control enables people to control a computer by using eye-gaze to select items on screen. Gaze-control is a necessity
for people who have lost all motor control of their body and only have control over eye movements. In addition, gaze-control
can be the quickest and least tiring option for a far broader group of people with varying disabilities. This paper reports
findings from gaze-control user trials involving users from both groups: people who are totally paralyzed, as well as people
with a wide range of complex disabilities. The trials conducted involved four different centres supporting people with disabilities
in three different European countries. Several gaze-control systems were trialled by a large number of users with varying
needs and abilities. The perceived benefits of gaze-control are described, and recommendations for successful assessment and
implementation of gaze-control are provided. 相似文献
145.
Mancić A Fuchs J Antici P Gaillard SA Audebert P 《The Review of scientific instruments》2008,79(7):073301
In this paper, the absolute calibration of photostimulable image plates (IPs) used as proton detectors is presented. The calibration is performed in a wide range of proton energies (0.5-20 MeV) by exposing simultaneously the IP and calibrated detectors (radiochromic films and solid state detector CR39) to a source of broadband laser-accelerated protons, which are spectrally resolved. The final result is a calibration curve that enables retrieving the proton number from the IP signal. 相似文献
146.
One of the key time-domain closed-loop performance requirements is the closed-loop response decay ratio. In this paper, the decay ratios of the disturbance-rejection magnitude optimum (DRMO) tuning method [Vranci? D, Strmcnik S, Kocijan J. Improving disturbance rejection of PI controllers by means of the magnitude optimum method. ISA Trans 2004; 43: 73-84; Vranci? D, Strmcnik S. Achieving optimal disturbance rejection by using the magnitude optimum method. In: Pre-prints of the CSCC'99 conference. 1999. p. 3401-6] are analyzed and compared to decay ratios of two other modern tuning methods, i.e. the Kappa-Tau tuning method (based on time-domain step-response characteristics) [Astr?m KJ, H?gglund T. PID controllers: Theory, design, and tuning. 2nd ed. Instrument Society of America; 1995] and the non-convex optimization tuning method (based on frequency response) [Panagopoulos H, Astr?m KJ, H?gglund T. Design of PI controllers based on non-convex optimization. Automatica 1998; 34: 585-601; Panagopoulos H, Astr?m KJ, H?gglund T. Design of PID controllers based on constrained optimisation. IEE Proc Control Theory Appl 2002; 149 (1): 32-40]. It is shown that the DRMO method results in such a closed-loop response that the decay ratio is within a relatively narrow interval when compared to the other two methods. 相似文献
147.
The experimentally determined chromaticities and reflectance spectra of films consisting of uniform ellipsoidal or spherical colloidal hematite particles are compared with calculated values and are found to be in good agreement. The theoretical treatment of the light-scattering problem involves the Mie theory for the spheres and the T-matrix method for the ellipsoids. The reflectance spectra for the pigment films are calculated through the use of the Kubelka-Munk analysis. 相似文献
148.
The analysis of statistical parameters of computer-generated therfial images by a line-scanning technique indicates an approach to efficient image transmission. 相似文献
149.
Algorithm for the determination of intrinsic optical constants of metal films: application to aluminum 总被引:2,自引:0,他引:2
Rakić AD 《Applied optics》1995,34(22):4755-4767
Optical and electron-energy-loss data for evaporated-aluminum films have been critically analyzed and used in an iterative, self-consistent algorithm that represents a combination of the Kramers-Kronig analysis and the semiquantum-model application. The novel values of the intrinsic optical functions of aluminum have been determined in a wide spectral range from 200 μm (6.2 meV) to 0.12 nm (10 keV). These functions are in accordance with recent calculations by Lee and Chang [Phys. Rev. B 49, 2362 (1994)], with dc conductivity measurements, and are in good agreement with both peak positions and line widths obtained from electron-energy-loss experiments. The results are examined for internal consistency by inertial and f-sum rules. 相似文献
150.
Gisler T Rüger H Egelhaaf SU Tschumi J Schurtenberger P Rička J 《Applied optics》1995,34(18):3546-3553
We present a quantitative experimental comparison of fiber-based, single- and few-mode dynamic light scattering with the classical pinhole-detection optics. The recently presented theory of mode-selective dynamic light scattering [Appl. Opt. 32, 2860 (1993)] predicts a collection efficiency and a signal-tobaseline ratio superior to that of a classical pinhole setup. These predictions are confirmed by our experiments. Using single-mode optical fibers with different cutoff wavelengths and commercially available mechanical components, we have constructed a mode-selective detection optics in a simple and compact dynamic light-scattering spectrometer that permits an optimal compromise between signal intensity and dynamical resolution. 相似文献