全文获取类型
收费全文 | 775篇 |
免费 | 31篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 189篇 |
金属工艺 | 13篇 |
机械仪表 | 15篇 |
建筑科学 | 22篇 |
能源动力 | 30篇 |
轻工业 | 41篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 118篇 |
一般工业技术 | 143篇 |
冶金工业 | 92篇 |
原子能技术 | 4篇 |
自动化技术 | 121篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 20篇 |
2021年 | 30篇 |
2020年 | 16篇 |
2019年 | 14篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 29篇 |
2015年 | 26篇 |
2014年 | 42篇 |
2013年 | 55篇 |
2012年 | 36篇 |
2011年 | 55篇 |
2010年 | 35篇 |
2009年 | 33篇 |
2008年 | 41篇 |
2007年 | 38篇 |
2006年 | 34篇 |
2005年 | 23篇 |
2004年 | 31篇 |
2003年 | 26篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 17篇 |
1997年 | 21篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 14篇 |
1975年 | 3篇 |
1972年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有806条查询结果,搜索用时 8 毫秒
81.
Q. Arnaud 《Journal of Low Temperature Physics》2014,176(5-6):924-929
Cryogenic germanium detectors used in dark matter searches operate at ranges of low temperature \(<\) 100 \(\mathrm {mK}\) and electric field \(\sim \) 1 \(\mathrm {V/cm}\) such that charge trapping in the bulk of the detector plays a significant role in the net charge collected following a particle interaction. It is shown that in EDELWEISS FID800 detectors, these trapped charges induce residual charge signals that perturb the measurement of the total charge, significantly degrading the energy resolution at high energy. It is also shown that, by reading out the signal on all the electrodes, it is possible to clearly identify these effects and correct the total charge measurement accordingly, resulting in a \(\sim \) 30 % improvement of the resolution at high energy. This effect is demonstrated with data. A simple analytical model based on Shockley-Ramo’s theorem is presented, whereby this effect is due to the position dependence of signals induced by trapped charges. 相似文献
82.
Jonas Croissant Arnaud Chaix Olivier Mongin Miao Wang Sébastien Clément Laurence Raehm Jean‐Olivier Durand Vincent Hugues Mireille Blanchard‐Desce Marie Maynadier Audrey Gallud Magali Gary‐Bobo Marcel Garcia Jie Lu Fuyuhiko Tamanoi Daniel P. Ferris Derrick Tarn Jeffrey I. Zink 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(9):1752-1755
83.
Arthur Levy Steven Le Corre Arnaud Poitou 《International Journal of Material Forming》2014,7(1):39-51
Ultrasonic continuous welding of thermoplastic composite plates is a very promising process of particular interest for the assembly of aeronautics large parts. Its modeling and simulation however suffers from the difficulty of accounting for the very different time scales that rule the thermo-mechanical phenomena at the level of the adhesion zone. This problem was addressed in our previous works and led to an original simulation tool presented in Levy et al. (Eur J Mech A, Solids 30(4):501–509, 2011a). In this paper, the adopted time-homogenized multiphysical modeling of the flow at the mesoscopic scale of the energy directors is first presented. Then, using the numerical software in a 2D approach, an extensive numerical parametric study of the process is presented. The phenomena allowing welding are confirmed to be an initial strain concentration in the energy director, and the formation of a flowing fold. The influence of the following process parameters are finally investigated: amplitude of vibrations, holding force of the sonotrode, thickness of the plates, radius of curvature at the tip of the director, angle of the director. Process efficiency and weld quality is evaluated through simple indicators such as the equivalent stiffness analysis, the healing degree and the risk of porosity entrapment. The present study, carried at the mesoscopic scale, provides a better understanding of the complex interactions between physical and process parameters and enables to draw important technological conclusions for the design of energy directors. 相似文献
84.
Arnaud Delcorte Barbara J. Garrison 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(14):1572-1577
This contribution focuses on the conditions required to desorb a large hydrocarbon molecule using light-element clusters. The test molecule is a 7.5 kDa coil of polystyrene (PS61). Several projectiles are compared, from C60 to 110 kDa organic droplets and two substrates are used, amorphous polyethylene and mono-crystalline gold. Different aiming points and incidence angles are examined. Under specific conditions, 10 keV nanodrops can desorb PS61 intact from a gold substrate and from a soft polyethylene substrate. The prevalent mechanism for the desorption of intact and ‘cold’ molecules is one in which the molecules are washed away by the projectile constituents and entrained in their flux, with an emission angle close to ∼70°. The effects of the different parameters on the dynamics and the underlying physics are discussed in detail and the predictions of the model are compared with other published studies. 相似文献
85.
J L Willems P Arnaud J H van Bemmel P J Bourdillon R Degani B Denis F M Harms P W Macfarlane G Mazzocca J Meyer 《Computers and biomedical research》1985,18(5):439-457
As a result of an international cooperative project entitled "Common Standards for Quantitative Electrocardiography" (CSE), an ECG reference data base has been established with the aim of standardizing computer-derived ECG measurements. The objective of the project is to reduce the wide variation in wave measurements currently obtained by ECG analysis programs. A library of 250 ECGs with selective ECG abnormalities was established and a comprehensive reviewing scheme was devised for the visual determination of the onsets and offsets of P, QRS, and T. This task was performed by a board of cardiologists on highly amplified, selected complexes from the library. A subset was examined in order to study beat-to-beat and intraobserver variability. By using a modified Delphi approach, individual outlying point estimates were eliminated in four successive rounds. In this way final referee estimates were obtained which proved to be highly reproducible and precise. A reference library has thereby been developed which allows testing of the performance of ECG measurement programs and is a useful instrument in establishing recommendations for more precise measurement rules and definitions. 相似文献
86.
The success of several constraint-based modeling languages such as OPL, ZINC or COMET, appeals for better software engineering
practices, particularly in the testing phase. This paper introduces a testing framework enabling automated test case generation
for constraint programming. We propose a general framework of constraint program development which supposes that a first declarative
and simple constraint model is available from the problem specifications analysis. Then, this model is refined using classical
techniques such as constraint reformulation, surrogate, redundant, implied, global constraint and symmetry-breaking to form
an improved constraint model that must be thoroughly tested before being used to address real-sized problems. We think that
most of the faults are introduced in this refinement step and propose a process which takes the first declarative model as
an oracle for detecting non-conformities and derive practical test purposes from this process. We implemented this approach
in a new tool called CPTEST that was used to automatically detect non-conformities on classical benchmark programs, such as the Golomb rulers, n-queens,
social golfer and the car-sequencing problems. 相似文献
87.
OBJECTIVE: The purpose of our prospective study was to evaluate the contribution of follow-up in resected colorectal cancer. METHODS: One-thousand patients with colorectal adenocarcinoma who underwent radial resection from January 1975 to January 1990 were prospectively divided into two groups: the first group (n = 442, 42%) entered a 5-year follow-up protocol and the second group (n = 558, 56%) was free to make unscheduled visits in case of symptoms. RESULTS: Recurrence was found in 31.5% of the patients in the first group compared with 33% in the second group. Chorioembryonic antigen was the most accurate test detecting recurrence: 77% of the cases (97% for hepatic metastasis). Surgical resection of recurrent tumors was performed in 37% of the group 1 patients (curative resection in 15%) and in 9% (curative resection in 1.5%) of the group 2 patients (p < 0.001). 5-year survival after recurrence in group 1 was 11.5% versus 1% in group 2 (p < 0.01). CONCLUSION: These results emphasize the rational for a follow-up program in patients undergoing surgery for colorectal cancer. 相似文献
88.
The operation of graded-index fibres can be optimised in the neighbourhood of some wavelength whenever two dopants are available. Under the assumption that the index is a linear function of the dopant concentrations, a class of relations between dopants is found, which is related to that given by Olshansky.4 The case of a fibre doped with germanium and fluorine is treated. 相似文献
89.
It is shown experimentally that short samples (about 1 m) of multimode optical fibres can be characterised by measuring the times of flight of tubular modes. There is fair agreement between measured and calculated values. 相似文献
90.
A closed-form expression for pulse broadening in graded-index fibres that have small and circularly symmetric, but otherwise arbitrary, deviations from a square-law, and arbitrary dn/d?, is applied to germania-doped fibres. The range of validity of the theoretical expression is defined by comparison with the results of numerical integration. 相似文献