全文获取类型
收费全文 | 169篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 39篇 |
金属工艺 | 4篇 |
机械仪表 | 3篇 |
建筑科学 | 14篇 |
能源动力 | 15篇 |
轻工业 | 9篇 |
水利工程 | 1篇 |
无线电 | 17篇 |
一般工业技术 | 30篇 |
冶金工业 | 9篇 |
原子能技术 | 9篇 |
自动化技术 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 7篇 |
2011年 | 11篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有178条查询结果,搜索用时 8 毫秒
171.
A novel technique of lidar for atmospheric gas detection by use of stimulated Raman gain spectroscopy without any tunable laser is proposed. Detection sensitivity and detectable range are estimated on the basis of the lidar equation for CO2, CH4, and H2 in the atmosphere. The feasibility study clearly shows that the technique has a potential for application to lidar and that, in addition, the construction of the system is simpler than those of traditional differential absorption lidars. 相似文献
172.
TE0-TM0 mode conversion by acousto-optic effects has been demonstrated using an amorphous-tellurium-dioxide optical waveguide and ? quartz substrate. An acoustic surface wave with a frequency of 160 MHz was used to induce photoelastic coupling in the waveguide. The incident angle of the optical beam with respect to the acoustic wavefront for obtaining TE0-TM0 crosscoupling agrees well with the value predicte from abnormal Bragg diffraction. 相似文献
173.
Rice as the most influential source of cadmium intake among general Japanese population 总被引:9,自引:0,他引:9
Tsukahara T Ezaki T Moriguchi J Furuki K Shimbo S Matsuda-Inoguchi N Ikeda M 《The Science of the total environment》2003,305(1-3):41-51
The objective of the present study is to examine whether rice is still a leading source of cadmium (Cd) burden among general populations in Japan. For this purpose, 10 prefectures were selected from all over Japan (including the northern- and southern-most Hokkaido and Okinawa prefecture, respectively). Cadmium levels in urine of never-smoking women (corrected for creatinine; Cd-Ucr) were compared with the rice- and wheat product-based Cd intake, which were estimated from Cd contents in rice and wheat (in the forms of bread, noodle and flour) consumed by residents in the areas, and per-capita daily consumption of rice and wheat. Stepwise multiple regression analysis taking Cd-Ucr as a dependent variable and rice- or wheat product-based Cd intakes as independent variables showed that rice was the most influential and almost exclusive variable with a partial correlation coefficient of 0.770-0.832, explaining 59-69% of total variation in Cd-Ucr. The effects of other sources including wheat were essentially negligible. 相似文献
174.
TiN film is often coated on alumina rf windows to suppress multipactor due to high secondary electron emission (SEE) coefficients. In this paper, SEE coefficients of alumina ceramics and sapphire coated with TiN films of various thicknesses are investigated. The SEE coefficients were measured using a scanning electron microscope with a single-pulse electron beam (100 pA, 1 ms). The SEE coefficients of TiN-coated alumina ceramics were lower than those of uncoated ones and nearly unity for TiN thickness of more than 1 nm, even with incident energy of 1 keV. To emulate multipactor-induced surface heating, the SEE coefficients were also measured at high temperature. The results showed a decrease in the SEE coefficients with temperature for TiN thickness of more than 0.5 nm. TiN coating on an rf window should be as thin as possible, and 0.5-1 nm may be the optimum thickness for suppressing multipactor. 相似文献
175.
High-power piezoelectric characteristics of textured bismuth layer structured ferroelectric ceramics
Ogawa H Kawada S Kimura M Shiratsuyu K Sakabe Y 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(12):2500-2504
Abstract-The high-power piezoelectric characteristics in h001i oriented ceramics of bismuth layer structured ferroelectrics (BLSF), SrBi(2)Nb(2)O(9) (SBN), (Bi,La)(4)Ti(3)O(12) (BLT), and CaBi(4)Ti(4)O(15) (CBT), were studied by a constant voltage driving method. These textured ceramics were fabricated by a templated grain growth (TGG) method, and their Lotgering factors were 95%, 97%, and 99%, respectively. The vibration velocities of the longitudinal mode (33-mode) increased proportionally to an applied electric field up to 2.5 m/s in these textured BLSF ceramics, although, the vibration velocity of the 33-mode was saturated at more than 1.0 m/s in the Pb(Mn,Nb)O(3)-PZT ceramics. The resonant frequencies were constant up to the vibration velocity of 2.5 m/s in the SBN and CBT textured ceramics; however, the resonant frequency decreased with increasing over the vibration velocity of 1.5 m/s in the BLT textured ceramics. The dissipation power density of the BLT was almost the same as that of the Pb(Mn,Nb)O(3)-PZT ceramics. However, the dissipation power densities of the SBN and CBT were lower than those of the BLT and Pb(Mn,Nb)O(3)-PZT ceramics. The textured SBN and CBT ceramics are good candidates for high-power piezoelectric applications. 相似文献
176.
Yutaka Kishida Naohiko Imaizumi Hirohisa Tanimura Shinichiro Kashiwamura Toru Kashiwagi 《International journal of molecular sciences》2016,17(3)
The restoration of innate immune responses has potential as a novel therapeutic strategy for chronic hepatitis C (CHC). We compared the efficacy and safety of induction therapy (IT) with natural interferon-β (n-IFN-β) followed by pegylated-IFN-α/ribavirin (PR) alone (group A, n = 30) and IT with a protease inhibitor (PI) (simeprevir or vaniprevir)/PR (group B, n = 13) in CHC patients with genotype 1b and high viral loads. During IT with nIFN-β, virologic response rates in group A and group B were 10% and 8% (p = 0.6792) at week 4, 30% and 16% (p = 0.6989) at week 12 and 47% and 20% (p = 0.0887) at week 24 respectively. During and after the treatment with PR alone or PI/PR, virologic response rates in groups A and B were 50% and 82% (p = 0.01535) at week 4, 53% and 91% (p = 0.006745) at week 8, 57% and 91% (p = 0.001126) at week 12, 57% and 100% (p < 0.001845) at the end of the treatment and 57% and 80% (p < 0.005166) after treatment cessation. IT with PI/PR linked to the restoration of innate immune response was tolerated well, overcame virological breakthrough, enhanced early virologic responses, and resulted in a sustained virologic response in difficult-to-treat CHC patients. IT with PI/PR is beneficial for treating difficult-to-treat CHC patients. 相似文献
177.
The phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends was studied in relation to the molecular weight. The samples were prepared by both solution blends, which showed two glass‐transition temperatures (Tg), and melt blends (MQ), which showed a single Tg, depending on the composition of the blends. The Tg of the MQ series was independent of the molecular weight of the homopolymer, although the degree of transesterification in the blends was affected by the molecular weight. The MQ series showed two exotherms during the heating process of a differential scanning calorimetry scan. The peak temperature and the heat flow of the exotherms were affected by the molecular weight of the homopolymers. The strain‐induced crystallization of the MQ series suggested the independent crystallization of PET and PEN. Based on the results, a microdomain structure of each homopolymer was suggested. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2428–2438, 2005 相似文献
178.
The stress relaxation behaviour of liquid crystal-forming ethyl celllulose (EC) solutions in m-cresol was determined by means of a cone-plate type viscometer at 30°C. The effect of molecular weight (MW) on the behaviour was also determined. The relaxation behaviour could be fitted with the following equation: where σi and σf are steady-state shear stresses at shear rate $\dot \gamma _{\rm i}$ and $\dot \gamma _{\rm f}$, σ(t) is time- dependent stress, A1 and A2 are constants, τ1 and τ2 are relaxation times, t is time, and tc is a characteristic time. When log σ* was plotted against time, one straight line was obtained for isotropic solutions, whereas anisotropic solutions yielded two straight lines. This suggests that the liquid crystalline solutions have two separate relaxation processes: Process 1 has a relatively short relaxation time, and process 2 has a long one. The parameters τ1, τ2, and A2 were greatly dependent on polymer concentration, combination of $\dot \gamma _{\rm i}$ and $\dot \gamma _{\rm f}$, and MW, whereas A1 was independent thereof and was close to unity. The process 1 was supposed to be valid for individual molecules, and process 2 for liquid crystalline domains or randomly aggregated or entangled molecules. 相似文献