全文获取类型
收费全文 | 1269篇 |
免费 | 41篇 |
专业分类
电工技术 | 127篇 |
综合类 | 2篇 |
化学工业 | 372篇 |
金属工艺 | 33篇 |
机械仪表 | 48篇 |
建筑科学 | 23篇 |
能源动力 | 86篇 |
轻工业 | 95篇 |
水利工程 | 2篇 |
无线电 | 73篇 |
一般工业技术 | 273篇 |
冶金工业 | 29篇 |
原子能技术 | 41篇 |
自动化技术 | 106篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 25篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 43篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 89篇 |
2012年 | 77篇 |
2011年 | 74篇 |
2010年 | 76篇 |
2009年 | 65篇 |
2008年 | 64篇 |
2007年 | 64篇 |
2006年 | 61篇 |
2005年 | 52篇 |
2004年 | 40篇 |
2003年 | 40篇 |
2002年 | 38篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 22篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 22篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 5篇 |
1987年 | 17篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 15篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1971年 | 3篇 |
排序方式: 共有1310条查询结果,搜索用时 15 毫秒
91.
Yoshihiro Kanno 《Optimization and Engineering》2016,17(4):861-896
It is classical that, when the small deformation is assumed, the incremental analysis problem of an elastoplastic structure with a piecewise-linear yield condition and a linear strain hardening model can be formulated as a convex quadratic programming problem. Alternatively, this paper presents a different formulation, an unconstrained nonsmooth convex optimization problem, and proposes to solve it with an accelerated gradient-like method. Specifically, we adopt an accelerated proximal gradient method, that has been developed for a regularized least squares problem. Numerical experiments show that the presented algorithm is effective for large-scale elastoplastic analysis. Also, a simple warm-start strategy can speed up the algorithm when the path-dependent incremental analysis is carried out. 相似文献
92.
Yoshihiro Maruyama Takumi Hamaguchi Tien-Hsiu Tsai 《Journal of Nuclear Science and Technology》2018,55(2):199-208
A new ‘transXend’ detector system has been developed for energy-resolved computed tomography (CT). It consists of several segmented detectors that measure X-rays as electric currents. Response functions of segmented detectors are estimated using component materials of a body under inspection to unfold X-ray spectra. To avoid material-dependent measurements, response functions inherent to segmented detectors are evaluated by Monte Carlo calculations. CT was performed for a phantom consisting of five resins and was analyzed by the estimated response functions. The linear attenuation coefficients for the five resins have excellent agreement with database values. 相似文献
93.
Amorphous and crystallized poly(L -lactic acid) (PLLA) films were prepared and the hydrolytic degradation of the ultraviolet (UV)-treated and UV-nontreated films was investigated. This study reveals that the combination of UV and thermal treatments can produce the PLLA materials having different hydrolytic degradation profiles and that the UV-irradiation in the environment will affect the design of recycling process for PLLA articles. In an early stage, the degrees of hydrolytic degradation monitored by weight loss (Wloss), number-average molecular weight (M n), and melting temperature (T m) were higher for the UV-treated films than for the UV-nontreated films. In a late stage, the trend traced by Wloss was reversed, and the difference in the degrees of hydrolytic degradation between the UV-treated and UV-nontreated films monitored by M n and T m became smaller, with the exception of the degrees of hydrolytic degradation of the amorphous films traced by T m. Also, in the early stage, the degrees of hydrolytic degradation monitored by Wloss and M n were higher for the crystallized films than for the amorphous films. In the late stage, this trend was reversed, with the exception of the degrees of hydrolytic degradation of the UV-treated films monitored by M n. The main factors that determined the Wloss and T m were the molecular weight and initial crystallinty but not the molecular structures such as terminal CC double bonds and crosslinks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
94.
2-n-Butylaminonaphthazarin (2) absorbs at 499 and 532 nm in ethanol but at 539 and 577 nm in alkali solution, while 2, 6-bis(n-butylamino)naphthazarin (3) absorbs at 461, 500 and 540 nm in ethanol but at 511 and 545 nm in alkali solution, with only a small bathochromic shift of 5 nm. The absorption curve of 3 was changed by addition of alkali and the λDmax at around 461 nm completely disappeared. In the case of 2-bromo-3, 6-bis(n-butylamino)naphthazarin (4), tautomerism between the 1, 4-quinone and 1, 5-quinone forms was observed and the isosbestic point was observed at 480 nm. Dye 2 easily deprotonated to give the 1, 4-dianion, but dyes 3 and 4 existed as tautomeric mixtures in solution and shifted to 1, 5-quinone forms in alkali solution. 相似文献
95.
Kholid Akhmad Hiroaki Okamoto Akio Kitamura Hiromu Matsuda Fumio Yamamoto Yoshihiro Hamakawa 《Solar Energy Materials & Solar Cells》1997,47(1-4)
The experiments investigated phenomena related to direct contact between the DC output of a PV array and the AC power from the utility grid. The results show that the DC power flows through the distribution transformers (DC-injection) saturating their magnetic circuits. The saturation of magnetic circuits makes peak currents, incorporating a large portion of even harmonics, flow through the high-voltage side of the distribution transformer, adding the level of harmonic distortion of its exciting current. With the increase of injecting DC-current to the utility grid, peak currents at the primary side of distribution transformer increases the most, and even among the same effective (rms) values, the increase of primary side current is larger than that of the secondary side current. 相似文献
96.
Yoshihiro Imai Tadashi Tokumasu Hidehiro Nagamura Kiyoshi Miyaike Hisakazu Matsumoto Hiroshi Hasegawa Hiroshi Kusafuka Masatoyo Shibuya Ryukichi Takahashi 《Electrical Engineering in Japan》2007,160(2):30-38
In the combined‐cycle power plant generators are started by using the igniting arrangement up to the ignition rotational speed of the gas turbine. On the other hand, in the case of using the superconducting generator, it is difficult to apply the igniting arrangement used to generate electricity on the combined cycle for the structure as is. We examined the induction motor starting method for the superconducting generator by using the 70‐MW‐class quick‐response excitation superconducting model generator and the VVVF power supply. From the examination, we confirmed the ability to raise the rotational speed from 6 to 360 rpm. Moreover, it was found to be able to start 200‐MW‐class superconducting generators by the induction motor starting method with the analysis. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(2): 30– 38, 2007; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20283 相似文献
97.
Shigeki Tasaka Yoshihiro Sato Nobuhito Tateyama Hisahiko Sugimoto Fumihito Fumuro Kaoru Hoshino 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,236(2):400-409
A new multiple scanning method is developed and applied to detect cosmic heavy nuclei. The plastic track detectors CR-39 exposed to cosmic heavy nuclei are over-etched in 8.0N NaOH for 94 h at 80°C. We found that the etched cones can easily be scanned on the plastic plates without using an optical microscope. The trajectories of heavy nuclei can be reconstructed with the naked eyes by superposing four or more over-etched plates. The charge detection threshold is obtained by this method, and appears to be 10. The charge resolution is estimated to be 1.0 charge units for iron nuclei. By adopting this method, the scanning time is much shortened and CR-39 plastic chamber size can easily be scaled up. The method is very useful for detecting particles with low flux intensity, like for searching magnetic monopoles or for measuring the high energy spectra of cosmic heavy nuclei. 相似文献
98.
99.
Ryo Watada Makoto Ohsaki Yoshihiro Kanno 《Structural and Multidisciplinary Optimization》2011,43(4):459-471
Uniqueness and symmetry of solution are investigated for topology optimization of a symmetric continuum structure subjected
to symmetrically distributed loads. The structure is discretized into finite elements, and the compliance is minimized under
constraint on the structural volume. The design variables are the densities of materials of elements, and intermediate densities
are penalized to prevent convergence to a gray solution. A path of solution satisfying conditions for local optimality is
traced using the continuation method with respect to the penalization parameter. It is shown that the rate form of the solution
path can be formulated from the optimality conditions, and the uniqueness and bifurcation of the path are related to eigenvalues
and eigenvectors of the Jacobian of the governing equations. This way, local uniqueness and symmetry breaking process of the
solution are rigorously investigated through the bifurcation of a solution path. 相似文献
100.