全文获取类型
收费全文 | 2442篇 |
免费 | 47篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 83篇 |
综合类 | 5篇 |
化学工业 | 575篇 |
金属工艺 | 113篇 |
机械仪表 | 75篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 67篇 |
轻工业 | 124篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 251篇 |
一般工业技术 | 356篇 |
冶金工业 | 632篇 |
原子能技术 | 52篇 |
自动化技术 | 131篇 |
出版年
2023年 | 9篇 |
2022年 | 31篇 |
2021年 | 40篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 25篇 |
2017年 | 11篇 |
2016年 | 27篇 |
2015年 | 24篇 |
2014年 | 39篇 |
2013年 | 90篇 |
2012年 | 53篇 |
2011年 | 98篇 |
2010年 | 70篇 |
2009年 | 94篇 |
2008年 | 100篇 |
2007年 | 78篇 |
2006年 | 62篇 |
2005年 | 80篇 |
2004年 | 65篇 |
2003年 | 67篇 |
2002年 | 62篇 |
2001年 | 64篇 |
2000年 | 51篇 |
1999年 | 67篇 |
1998年 | 222篇 |
1997年 | 168篇 |
1996年 | 120篇 |
1995年 | 68篇 |
1994年 | 64篇 |
1993年 | 66篇 |
1992年 | 37篇 |
1991年 | 32篇 |
1990年 | 30篇 |
1989年 | 29篇 |
1988年 | 22篇 |
1987年 | 27篇 |
1986年 | 12篇 |
1985年 | 26篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 26篇 |
1981年 | 23篇 |
1980年 | 23篇 |
1979年 | 28篇 |
1978年 | 8篇 |
1977年 | 21篇 |
1976年 | 38篇 |
1975年 | 12篇 |
1966年 | 6篇 |
排序方式: 共有2498条查询结果,搜索用时 15 毫秒
101.
S.T. Nakagawa H. Hashimoto H. Kanda A. Okamoto M. Ohishi H. Saito G. Betz 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1226-1228
In order to advance quantum computer after successful synthesis of a qubit (quantum-bit) using a NV (nitrogen-vacancy) center in diamond crystal, the innovation of a NOT processor is strongly demanded. A candidate of it can be one NV center associated with an additional N atom, which is called a NV–N center. Making use of a classical molecular dynamics simulation of N ion implantation into pure diamond with an energy of 200 eV, we have examined the crystallographic structure of “NV–N” centers. However, at low temperature of 30 K, most implanted N atoms became interstitials, thus it was difficult to identify even NV centers. 相似文献
102.
103.
Preparation of sharp-melting hard palm midfraction and its use as hard butter in chocolate 总被引:1,自引:0,他引:1
Satsuki Hashimoto Toru Nezu Hiroshi Arakawa Tomonori Ito Shoji Maruzeni 《Journal of the American Oil Chemists' Society》2001,78(5):455-460
Preparation of hard palm midfractions (PMF) and its use as a cocoa butter equivalent ingredient were studied. Hard PMF is
obtained by multistep fractionation of palm oil involving dry fractionation (DF) and/or solvent fractionation (SF), usually
using hexane or acetone. From our experience, in acetone, a polar solvent, symmetrical 1,3-disaturated triacylglycerols tend
to selectively crystallize more than nonsymmetrical 1,2- or 2,3-disaturated triacylglycerols, making it suitable for obtaining
the solid midfraction. Unfortunately, triacylglycerols are very soluble in hexane, and temperatures at least 15 degrees lower
than those required for acetone must be used for equivalent crystal yields. On the other hand, DF is a less expensive and
safer process. Thus, multistep fractionation combining DF and SF using acetone was developed to achieve sufficient removal
of high-melting components, and further enrichment of 1,3-dipalmitoyl-2-oleoylglycerol and the hard PMF was obtained by triple-step
fractionation of palm olein or double-step fractionation of soft PMF. Compared to conventional hard PMF, this hard PMF had
a steeper melting curve and better snapping and sharp-melting qualities when used in chocolate. Heat resistance of the hard
PMF chocolate was similar to the conventional hard PMF chocolate, and its bloom resistance could be improved by adding polyglycerol
fatty acid esters. 相似文献
104.
Alkhateib Y. Gaafar Hirofumi Yamashita Indah Istiqomah Yasuhiko Kawato Kanae Ninomiya Abdelgayed Younes Toshihiro Nakai 《Microscopy research and technique》2020,83(8):979-987
The practical difficulty of parenteral application of fish vaccines against devastating fish diseases diverted the interest toward oral vaccination. Search for effective methods to enhance the oral uptake of viral and bacterial vaccines is continuing. The current research focus on a new role of mucosal fish vaccine adjuvants inducing the antigen uptake by enhancing vascularity or increasing intestinal permeability. Some inflammatory substances cause reversible pathology to the intestinal epithelium, which could be employed for the transepithelial passage of vaccine particles. The natural inflammatory substances used were capsaicin, piperine, and okadaic acid as 1 mg, 2 mg, and 1 μg/fish, respectively. Two inactivated vaccines were used as antigens to test the effect of these inflammatory substances in two different fish hosts. Tested vaccines were inactivated redspotted grouper nervous necrosis virus vaccine in sevenband grouper (Epinephelus septemfasciatus) and inactivated Edwardsiella tarda vaccine in red sea bream (Pagrus major) fish models. The inflammatory substances and each vaccine were anally intubated to fish. Capsaicin proved to be effectively aiding the transepithelial passage of vaccine particles more than piperine, while okadaic acid had no detectable effect. 相似文献
105.
For a better understanding of the atmospheric rusting of iron and steels, the present work is aimed to explore the mechanism of formation of green rusts, Fe3O4, α-FeOOH, β-FeOOH, γ-FeOOH, δ-FeOOH and amorphous ferric oxyhydroxide in aqueous solution at room temperature. The formation processes on which end products are determined are strongly affected by the oxidation rate, pH and the structure and composition of initial and intermediate species of iron. The systematic diagram of formation processes of iron oxide and oxyhydroxides has been presented, in which both dissolved and solid species of iron are included. 相似文献
106.
Atmospheric rusting of mild and low alloy steels was studied by means of infra-red and far infra-red spectrophotometries, X-ray and electron diffraction methods and scanning electron microscopy. The rusting process can be interpreted on the basis of a previously reported diagram for rust formation in aqueous solution.A large amount of amorphous matter in rust formed in semi-rural atmosphere was identified by infra-red and far infra-red spectra as amorphous ferric oxyhydroxide, FeOx (OH)8–2x. The amorphous ferric oxyhydroxide rust on low alloy steel was dense and uniform, and contained a considerable amount of bound water. From these results it can be concluded that the amorphous ferric oxyhydroxide rust acts as a protective barrier against atmospheric rusting of the steels. Cu, P and Cr in low-alloy steels are inferred to favour the formation of crack-free, uniform rust layer and help to produce uniform amorphous ferric oxyhydroxide. 相似文献
107.
As a standard for identification of iron oxides by X-ray photoelectron spectroscopy, Fe2+ spectra are extracted from mixed Fe 2p3/2 spectra of Fe3+, Fe3+ and metallic states. The peaks of Fe2+ spectra are all located at binding energy of 708·5 eV. The width of Fe2+ spectrum seems to be dependent on crystallinity, and is 2·2 eV for a bulk crystalline oxide and 2·9 eV for an amorphous thin film under instrumental condition with FWHM of 1·3 eV for Au 4f7/2. 相似文献
108.
Hashimoto A Mitsuishi K Shimojo M Zhu Y Takeguchi M 《Journal of electron microscopy》2011,60(3):227-234
We experimentally examined the characteristics of bright-field (BF) scanning confocal electron microscopy (SCEM) images by changing the observation conditions and comparing the images with those obtained by BF transmission electron microscopy (TEM) and BF scanning TEM (STEM) modes. The observation of 5-nm-diameter Au nanoparticles demonstrated that BF-SCEM produces object elongation of more than 2000?nm along the optical axis, as do BF-TEM and BF-STEM. We demonstrated the relationship between elongation length and geometric effects such as convergence and collection angles of a probe and the lateral size of an object; the relationship is consistent with previous theoretical prediction. Further, we observed interesting features that are seen only in the BF-SCEM images; the film contrast was strongly enhanced, compared with that of BF-STEM. In addition, a bright contrast appeared around the object position in the elongated images. Using this characteristic, we could determine the object position and structure. 相似文献
109.
Toshihiko Kuwabara Kazuma Hashimoto Eiji Iizuka 《Journal of Materials Processing Technology》2011,211(3):475-481
The deformation behavior of 780 MPa grade dual-phase steel sheet subjected to hole expansion is investigated both experimentally and analytically to clarify the effect of the material model (anisotropic yield function) on the predictive accuracy of finite element analysis of hole expansion. Biaxial tensile tests of the material were conducted; contours of plastic work and the directions of plastic strain rates are precisely measured and are in good agreement with those predicted from the Yld2000-2d yield function with an exponent of 4 (
[Barlat et al., 2003] and [Yoon et al., 2004]). Finite element and experimental analyses on the hole expansion of the material were conducted. The Yld2000-2d yield function with an exponent of 4 provides closer agreement with the experimental results than other yield functions. Consequently, the anisotropic yield functions significantly affect the predictive accuracy of the deformation behavior of the steel sheet subjected to hole expansion, and the biaxial tensile test is effective for identification of the appropriate anisotropic yield function to be used for hole expansion simulation. 相似文献
110.
Shinobu Mukasa Tsunehiro Maehara Shinfuku Nomura Hiromichi Toyota Ayato Kawashima Yoshiaki Hattori Yukio Hashimoto Hiroshi Yamashita 《International Journal of Heat and Mass Transfer》2010,53(15-16):3067-3074
Plasma was generated in water by irradiation at high frequency of 13.56 MHz, and the behavior of bubbles including the plasma was observed by a high-speed camera. The generation pattern of the bubbles was classified into four types according to liquid temperature and supplied power. Conducting the simulation, the maximum temperature in the bubble was found to be from 3500 K to 4300 K, and the decomposition of water molecule occurred. The gas in the bubble was found to become high ratio of hydrogen. The phenomenon can be regarded as a film boiling of exceptionally high heat flux. 相似文献