全文获取类型
收费全文 | 2897篇 |
免费 | 51篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 133篇 |
综合类 | 2篇 |
化学工业 | 862篇 |
金属工艺 | 63篇 |
机械仪表 | 56篇 |
建筑科学 | 41篇 |
矿业工程 | 1篇 |
能源动力 | 93篇 |
轻工业 | 145篇 |
水利工程 | 6篇 |
石油天然气 | 4篇 |
无线电 | 223篇 |
一般工业技术 | 498篇 |
冶金工业 | 591篇 |
原子能技术 | 62篇 |
自动化技术 | 171篇 |
出版年
2023年 | 10篇 |
2022年 | 19篇 |
2021年 | 30篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 27篇 |
2017年 | 29篇 |
2016年 | 34篇 |
2015年 | 18篇 |
2014年 | 40篇 |
2013年 | 97篇 |
2012年 | 64篇 |
2011年 | 130篇 |
2010年 | 89篇 |
2009年 | 111篇 |
2008年 | 99篇 |
2007年 | 82篇 |
2006年 | 95篇 |
2005年 | 84篇 |
2004年 | 74篇 |
2003年 | 71篇 |
2002年 | 74篇 |
2001年 | 64篇 |
2000年 | 48篇 |
1999年 | 74篇 |
1998年 | 258篇 |
1997年 | 152篇 |
1996年 | 109篇 |
1995年 | 70篇 |
1994年 | 83篇 |
1993年 | 83篇 |
1992年 | 48篇 |
1991年 | 42篇 |
1990年 | 42篇 |
1989年 | 41篇 |
1988年 | 28篇 |
1987年 | 18篇 |
1986年 | 32篇 |
1985年 | 47篇 |
1984年 | 35篇 |
1983年 | 48篇 |
1982年 | 46篇 |
1981年 | 45篇 |
1980年 | 28篇 |
1979年 | 38篇 |
1978年 | 31篇 |
1977年 | 34篇 |
1976年 | 40篇 |
1975年 | 9篇 |
1974年 | 9篇 |
排序方式: 共有2951条查询结果,搜索用时 15 毫秒
1.
Ryo Hashikawa Yasuhiro Fujii Atsushi Kinomura Takeshi Saito Arifumi Okada Takashi Wakasugi Kohei Kadono 《Journal of the American Ceramic Society》2019,102(4):1642-1651
Radiophotoluminescence phenomena have been widely investigated on various types of materials for dosimetry applications. We report that an aluminoborosilicate glass containing 0.005 mol% copper exhibits intense photoluminescence in the visible region induced by X-ray and γ-ray irradiation. The luminescence is assigned to the 3d94s1 → 3d10 transition of Cu+. The proportionality of the intensity of the induced photoluminescence to the irradiation dose was confirmed up to 0.5 kGy using 60Co γ-ray irradiation. Based on the spectroscopic results, a potential mechanism was proposed for the enhancement of the photoluminescence. The exposure to the ionizing radiation generates electron-hole pairs in the glass, and the electrons are subsequently captured by the Cu2+ ions, which are converted to Cu+ and emit the luminescence. For the glass containing 0.01 mol% copper, the pronounced enhancement of the photoluminescence was not observed because the reverse reaction, ie, the capture of the holes by the Cu+ ions, becomes prominent. The photoluminescence induced by the irradiation was stably observed for the glasses kept at room temperature and even for the glasses heat-treated at 150°C. However, the induced photoluminescence could be eliminated by the heat treatment at a temperature at 500°C, and the glass returned to the initial pre-irradiation state. The Cu-doped aluminoborosilicate glass is a potential candidate for use in dosimetry applications. 相似文献
2.
H. Kanebako Y. Okada 《Mechatronics, IEEE/ASME Transactions on》2003,8(1):111-119
A new structure of hybrid (HB)-type self-bearing motor is proposed for miniature spindle motors. The proposed design combines the HB-type self-bearing motor and HB active magnetic bearing in the common stator and rotor pair to generate large radial forces. First, the principle and theoretical background are introduced. Then, the air gap flux is analyzed by the finite element method, and radial forces for the proposed and standard-type HB self-bearing motors are compared. Finally, experiments are conducted to confirm the performance of the proposed motor. The motor can run at relatively high rotating speed with relatively high torque compared with its small size. The levitation is very stable and the motor indicates good performance for practical application. 相似文献
3.
N Okada S Sato T Sasou M Aoyama K Nishida K Yoshikawa 《Canadian Metallurgical Quarterly》1993,129(4):403-407
Ambiguous abdominal situs, asplenia/polysplenia and severe cardiac malformations characterize heterotaxy in humans. These anomalies result from the inability of the developing embryo to establish normal left-right asymmetry. We have studied an interesting family in which the heterotaxy phenotype segregates as an X-linked recessive trait. In order to map the heterotaxy locus (HTX), we have analysed 39 family members using highly-polymorphic microsatellite markers from the X chromosome. One of these markers, DXS994, shows no recombination with the disease locus in 20 informative meioses. Linkage analysis results in a maximum lod score of 6.37. Current genetic and physical mapping data assign the order of loci in Xq24-q27.1 as cen-DXS1001-(DXS994, HTX)-DXS984-tel. These results establish the first mapping assignment of situs abnormalities in humans. 相似文献
4.
N Usui S Kamata S Ishikawa T Sawai H Okuyama K Imura A Okada 《Canadian Metallurgical Quarterly》1996,31(2):258-262
Bone marrow examination revealed a lipid-laden histiocytosis in seven patients undergoing long-term total parenteral nutrition necessitated by extensive short-bowel surgical resection. Clinical abnormalities occurred during this treatment which required bone marrow examination. These included hepatosplenomegaly and peripheral blood cytopenia; the median time to the detection of these abnormalities was 64 months. The most striking change within the bone marrow was the presence of many pigment-laden histiocytes which had the typical morphology of sea-blue histiocytes seen in the so-called idiopathic sea-blue histiocyte syndrome. The occurrence of sea-blue histiocytosis in the bone marrow in association with long-term parenteral nutrition for short-bowel syndrome has not, to our knowledge, been reported previously and should now be considered in the differential diagnosis of bone marrow sea-blue histiocytosis. 相似文献
5.
6.
The copreheat-treatment of non-fusible and slightly fusible coals with A240 and hydrogenated A240 under high temperature-short contact-time conditions around 500 °C has been examined in an attempt to produce a formed coke with better anisotropic development. These conditions shortened the copreheat-treatment time and provided better anisotropic development in the resultant coke after carbonization. Effectiveness of short contact-time has been discussed in terms of the extent of depolymerization of coal molecules suitable for anisotropic development, this being related to coal liquefaction under similar conditions. 相似文献
7.
Tsukada T. Hashimoto Y. Sakata K. Okada H. Ishibashi K. 《Solid-State Circuits, IEEE Journal of》2005,40(1):67-79
A decoupling circuit using an operational amplifier is proposed to suppress substrate crosstalk in mixed-signal system-on-chip (SoC) devices. It overcomes the parasitic inductance problem of on-chip capacitor decoupling. The effect of the proposed decoupling circuit is not limited by parasitic fine impedance. A 0.13-/spl mu/m CMOS test chip showed that substrate noise at frequencies from 40 MHz to 1 GHz was incrementally suppressed by sequentially activating three of the proposed circuits in parallel. The power dissipation of each circuit was 3.3 mW at a 1.0-V power supply. The test chip measurement showed that the proposed decoupling reduced crosstalk by 31% at 200 MHz, whereas it was reduced by 4.4% with capacitor decoupling. This 7:1 ratio, or 17 dB, corresponds to the gain of the opamp. Design of the opamp and its feedback loop for active decoupling is simple, making the opamp useful for SoC applications. 相似文献
8.
The diffusional behavior of multi-arm star-shaped p(tBMA) was investigated in a concentration range from dilute to semidilute region with 1H pulsed field gradient spin-echo NMR (PFGSE-NMR). An 142-arm star-shaped p(tBMA) showed two diffusional mode, which reflected the coexistence of liquid ordering phase and liquid phase near the ordering transition. On the other hand, for star-shaped p(tBMA) with 55 arms showed a single diffusional relaxation in all concentration ranges during observation time. In the semidilute region, the relationship between the diffusion coefficient against the polymer concentration was affected strongly not only the arm number but also liquid ordering structure. 相似文献
9.
Mitsuo Miyazawa Tomohiko Takahashi Kazuki Sakata Isao Horibe 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(7):1006-1011
BACKGROUND: The biotransformation of sesquiterpenoids, which are a large class of naturally occurring compounds, using microorganisms as a biocatalyst to produce useful novel organic compounds was investigated. The biotransformation of sesquiterpenoids, (+)‐aromadendrene ( 1 ), (−)‐alloaromadendrene ( 2 ) and (+)‐ledene ( 3 ) has been investigated using Aspergillus wentii as a biocatalyst. Results: Compound 1 was converted to (−)‐(10S,11S)‐10,13,14‐trihydroxyaromadendrane ( 4 ). Compound 2 was converted to (+)‐(1S,11S)‐1,13‐dihydroxyaromadendrene ( 5 ) and (−)‐5,11‐epoxycadin‐1(10)‐en‐14‐ol ( 6 ). Compound 3 was converted to compound 6 , (+)‐(10R,11S)‐10,13‐dihydroxyaromadendr‐1‐ene ( 7 ) and (+)‐(10S,11S)‐10,13‐dihydroxyaromadendr‐1‐ene ( 8 ). The structure of the metabolic products has been elucidated on the basis of their spectral data. CONCLUSION: Compound 1 gave only one product that was hydroxylated at C‐10, C‐13 and C‐14. By contrast, compounds 2 and 3 gave a number of products, one of which was common. The differences in oxidation of 1–3 are due to the configuration of the C‐1 position. Compounds 4–8 were new compounds. Copyright © 2008 Society of Chemical Industry 相似文献
10.
Inertinite concentrates from three Australian bituminous coals were hydrogenated at various temperatures ranging from 350 to 475 °C in the presence of tetralin without any added catalyst. Both conversion yields and microscopic observations of the benzene-extracted hydrogenation residues have revealed that the hydrogenation of the inertinite macerals becomes significant only > 400 °C, whereas the dissolution-hydrogenation of the accompanying vitrinite macerals occurs mainly between 350 and 400 °C. The major reaction pathway for the inertinite particles in the hydrogenation process appears to be one of initial mild carbonization followed by hydrogenation. A simplified reaction scheme is proposed which describes the reaction pathway involved in the hydrogenation of inertinite. 相似文献