全文获取类型
收费全文 | 2313篇 |
免费 | 34篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 99篇 |
综合类 | 1篇 |
化学工业 | 424篇 |
金属工艺 | 48篇 |
机械仪表 | 36篇 |
建筑科学 | 32篇 |
能源动力 | 59篇 |
轻工业 | 115篇 |
水利工程 | 4篇 |
无线电 | 450篇 |
一般工业技术 | 433篇 |
冶金工业 | 460篇 |
原子能技术 | 59篇 |
自动化技术 | 129篇 |
出版年
2022年 | 27篇 |
2021年 | 20篇 |
2020年 | 11篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 27篇 |
2015年 | 24篇 |
2014年 | 31篇 |
2013年 | 60篇 |
2012年 | 64篇 |
2011年 | 80篇 |
2010年 | 43篇 |
2009年 | 76篇 |
2008年 | 83篇 |
2007年 | 67篇 |
2006年 | 65篇 |
2005年 | 57篇 |
2004年 | 68篇 |
2003年 | 92篇 |
2002年 | 74篇 |
2001年 | 77篇 |
2000年 | 56篇 |
1999年 | 66篇 |
1998年 | 204篇 |
1997年 | 126篇 |
1996年 | 108篇 |
1995年 | 89篇 |
1994年 | 58篇 |
1993年 | 57篇 |
1992年 | 39篇 |
1991年 | 46篇 |
1990年 | 30篇 |
1989年 | 48篇 |
1988年 | 40篇 |
1987年 | 20篇 |
1986年 | 29篇 |
1985年 | 36篇 |
1984年 | 32篇 |
1983年 | 21篇 |
1982年 | 20篇 |
1981年 | 27篇 |
1980年 | 16篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 15篇 |
1976年 | 17篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有2349条查询结果,搜索用时 15 毫秒
31.
Itoh K. Watanabe W. Arimoto H. Isobe K. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2006,94(3):608-628
The basics of three-dimensional (3-D) and spectral imaging techniques that are based on the detection of coherence functions and other related techniques are reviewed. The principle of the 3-D source retrieval is based on understanding the propagation law of optical random field through the free space. The 3-D and spectral information are retrieved from the cross-spectral density function of optical random field or numerical calculation of the inverse propagation of the cross-spectral density. We will first introduce the coherence-based spectral tomography techniques with low-coherence light sources. These techniques limit their scheme of coherence detection only along the optical axis and some of them achieve simultaneously the high resolution and high speed of detection taking advantage of an imaging lens. We then provided explanations of the principle of 3-D source retrieval that is based on the propagation law of optical random field through the free space along with the introduction of the numerical holography and computed tomography techniques. We will lastly show 3-D spectral imaging schemes with the concurrent laser-scanning cross-sectioning techniques: one is the confocal laser scanning microscopy and the other is the two-photon laser-scanning fluorescence microscopy. 相似文献
32.
Effects of non-Gaussian concentration fluctuations in real time photon correlation spectroscopy were investigated with several sizes of mono-disperse polystyrene latex particles. The non-Gaussian correlation model for a full or a quasi-full (scaled) correlator showed good performance for particle sizing in the case of scaled correlation. The clipped correlation showed an equivalent performance with the scaled correlation except for the case of non-Gaussian fluctuation, where the measured diameter became inaccurate more rapidly with decreasing particle concentration in the scattering volume. The cause of such an instability of PCS in the clipped mode is attributed to baseline fluctuations of the correlogram induced by information loss of the clipped correlator. 相似文献
33.
Opportunistic infections are common and major causes of morbidity in patients with AIDS. Endemic mycoses pose serious risks for patients in certain parts of the world. Histoplasmosis occurs in 2-5% of patients with AIDS in the Ohio and Mississippi River valleys of the United States and in over 25% of patients from a few cities. Antigen testing has become a highly useful method for diagnosing histoplasmosis rapidly, evaluating the response to treatment and diagnosing relapse. Treatment with amphotericin B or itraconazole is effective (90% or higher) if the patient is not seriously ill at the time of diagnosis but the mortality approaches 50% for those with multiorgan failure. Itraconazole blood levels should be monitored and drugs that impair the absorption or accelerate the metabolism of itraconazole should be avoided. Prophylaxis with itraconazole may be appropriate in areas with an incidence of histoplasmosis. A recently completed study in cities which have unusually high rates of histoplasmosis will provide greater insight into the role of prophylactic antifungal therapy. 相似文献
34.
35.
Yasushi Nagato Seiji Higashitani Kotaro Yamada Katsuhiko Nagai 《Journal of Low Temperature Physics》1996,103(1-2):1-22
We present a Green's function theory of the rough surface effects on the anisotropic BCS states using the formulation developed in the randomly rippled wall model. It is shown that the randomly rippled wall formulation is general enough to treat rough surface effects from the specular limit to the diffusive limit. We propose a statistical wall configuration such that gives the diffusive limit in the normal state. Within the weak coupling theory, we give a formal solution of the quasi-classical Green's function in a slab geometry and in a semi-infinite geometry with arbitrarily rough surfaces. The formal solution already satisfies the boundary condition. In the diffusive limit, the present theory correctly recovers the linearized gap equation obtained by Kjäldman et al. for the p-wave state in a slab geometry. 相似文献
36.
Yasuyuki Itoh Tohru Sugawara 《Journal of Infrared, Millimeter and Terahertz Waves》1996,17(2):465-475
This paper describes a quasi-optical method for the conversion of modes transmitted through highly oversized circular waveguides. A waveguide-mode is radiated once from a waveguide cut in the form of a radiation beam, which is then properly shaped by two curved mirrors and directed back into the waveguide. The curved mirror shapes are iteratively and automatically determined for given propagation distances using the design technique for phase correction mirrors. The proposed method gives favorable results in designing a waveguide expander/reducer, a TE01-TE02 mode converter, and a TE01-HE11 mode converter. 相似文献
37.
Jing-Feng Li Ryuzo Watanabe Bo-Ping Zhang Katsuhiko Asami Koji Hashimoto 《Journal of the American Ceramic Society》1996,79(12):3109-3112
2 mol% Y2 O3 -ZrO2 polycrystals were annealed in water and under vacuum to highlight the effect of the presence of H2 O on the low-temperature degradation transformation. The specimen surfaces with monoclinic phases transformed during annealing in the different environments were analyzed by X-ray photoelectron spectroscopy with special interest on the electron binding energy change of the constituent ions of the 2 mol% Y2 O3 -ZrO2 ceramics after the degradation transformation. It was found that no change occurred for the electron-bonding energies of core levels of zirconium ions after the transformation, whereas Y-OH bonds were formed during annealing in water. This result suggested a possibility that the preferred hydration of yttrium took place at the surface of Y2 O3 -partially-stabilized ZrO2 , which is likely to be the reason for the low-temperature degradation accelerated by the presence of H2 O. 相似文献
38.
K. Nakano S. Tomiya M. Ukita H. Yoshida S. Itoh E. Morita M. Ikeda A. Ishibashi 《Journal of Electronic Materials》1996,25(2):213-216
Using electroluminescence (EL) topography and transmission electron microscopy (TEM), we investigated the nonluminescent regions
which form while current is being injected into ZnMgSSe/ZnSSe/ZnCdSe-based blue light emitters. Small dark spots were observed
just after turn-on and spread out forming rough nonluminescent triangles in the <100> directions in the EL image of the active
region. TEM studies showed that the small dark spots are pre-existing stacking faults originating at the substrate/epitaxial
layer interface. The nonluminescent triangles were found to be a dense region of dislocation dipoles and dislocation loops.
Each dipole was aligned along two <110> directions in the {111} planes. The Burgers vectors were of the type a/2<011> inclined
at 45° to the (001) junction plane. 相似文献
39.
Masaru Itoh 《The Structural Design of Tall and Special Buildings》1992,1(2):119-132
This paper summarizes the results of the wind design carried out for the Act Tower building in Japan. Wind tunnel tests were performed in order to estimate the building response for different wind directions. Undesirable building motion perceived by building occupants is also studied and antivibration systems have been installed to solve this problem. 相似文献
40.
Masahiro Baba Goh Itoh Haruhiko Okumura 《Journal of the Society for Information Display》2007,15(3):205-211
Abstract— In this paper, a software‐processed edge‐ and level‐adaptive overdrive (SELAO) method, which is a novel overdrive technique that utilizes not only a temporal change of gray levels but also a spatial edge intensity of motion pictures, is proposed. The SELAO method is a software video‐processing technology to improve motion‐picture quality rendered on LCDs more than is possible with a conventional SLAO method without edge‐adaptive overdrive, and it works in real time on commonly used personal computers (PCs). 相似文献