全文获取类型
收费全文 | 171篇 |
免费 | 30篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 44篇 |
金属工艺 | 7篇 |
机械仪表 | 15篇 |
建筑科学 | 2篇 |
能源动力 | 2篇 |
轻工业 | 43篇 |
无线电 | 31篇 |
一般工业技术 | 35篇 |
冶金工业 | 3篇 |
原子能技术 | 2篇 |
自动化技术 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 16篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2006年 | 2篇 |
2005年 | 10篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1989年 | 3篇 |
排序方式: 共有201条查询结果,搜索用时 15 毫秒
81.
Hemoglobin (Hb) is a member of the hemeprotein family that undergoes non-specific catalytic chain reactions in the presence of hydrogen peroxide (H2O2). The catalytic ability of Hb to degrade the carcinogenic polycyclic aromatic hydrocarbon pyrene was demonstrated using soil contaminated with 14C pyrene. Three bench-scale laboratory tests were performed using 14C pyrene in the presence of a buffer, H2O2, and a combination of Hb and H2O2. The initial pyrene concentration of the contaminated soil was set to 11 mg/kg, with 5,500,000 dpm of 14C pyrene. After a catalytic reaction for 24 h, the results showed that 17% of pyrene was degraded by H2O2, 38% of pyrene was degraded by Hb in combination with H2O2, and 0.13 and 1.2% of 14C pyrene were mineralized by H2O2 and Hb in combination with H2O2, respectively. An analysis of the products from the reaction involving Hb in combination with H2O2 revealed that 15.9% of the 14C intermediates in the acetonitrile fraction were polar products. After the catalytic reaction, 21 intermediate compounds were found via fraction analysis. The results suggested that Hb catalysis could be used to treat pyrene-contaminated soil as a novel catalytic technology for the remediation of hazardous materials in soil. 相似文献
82.
This paper describes a delay‐range‐dependent local state feedback controller synthesis approach providing estimation of the region of stability for nonlinear time‐delay systems under input saturation. By employing a Lyapunov–Krasovskii functional, properties of nonlinear functions, local sector condition and Jensen's inequality, a sufficient condition is derived for stabilization of nonlinear systems with interval delays varying within a range. Novel solutions to the delay‐range‐dependent and delay‐dependent stabilization problems for linear and nonlinear time‐delay systems, respectively, subject to input saturation are derived as specific scenarios of the proposed control strategy. Also, a delay‐rate‐independent condition for control of nonlinear systems in the presence of input saturation with unknown delay‐derivative bound information is established. And further, a robust state feedback controller synthesis scheme ensuring L2 gain reduction from disturbance to output is devised to address the problem of the stabilization of input‐constrained nonlinear time‐delay systems with varying interval lags. The proposed design conditions can be solved using linear matrix inequality tools in connection with conventional cone complementary linearization algorithms. Simulation results for an unstable nonlinear time‐delay network and a large‐scale chemical reactor under input saturation and varying interval time‐delays are analyzed to demonstrate the effectiveness of the proposed methodology. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
83.
The objective of this study was to evaluate the beneficial effect of α‐linolenic acid‐rich black raspberry seed (BRS) oil on lipid metabolism in high‐fat diet (HFD)‐induced obese and db/db mice. Five‐week‐old C57BL/6 mice were fed diets consisting of 50% calories from lard, 5% from soybean, and 5% from corn oil (HFD), or 50% calories from lard and 10% from BRS oil (HFD + BRS oil diet) for 12 weeks. Six‐week‐old C57BL/KsJ‐db/db mice were fed diets consisting of 16% calories from soybean oil (standard diet), 8% from soybean, and 8% from BRS oil, or 16% from BRS oil for 10 weeks. The BRS oil diets lowered the levels of triacylglycerol, nonesterified fatty acids, and total cholesterol in serum and liver of both of the obese and db/db mice as compared with the HFD and standard diet, respectively. mRNA levels of lipogenesis markers including cluster of differentiation 36, fatty‐acid‐binding protein 1, sterol regulatory element binding protein 1c, fatty‐acid synthase, and solute carrier family 25 member 1 in the liver of the BRS oil groups were lower than those in the liver of the HFD and standard groups in the obese and db/db mice, respectively. On the other hand, fatty‐acid oxidation markers including carnitine palmitoyltransferase 1A, acyl‐CoA dehydrogenase, hydroxylacyl‐CoA dehydrogenase α, and acyl‐CoA oxidase in the liver of the BRS oil groups were higher than those in the liver of the HFD and standard groups in the obese and db/db mice, respectively. Peroxisome proliferator‐activated receptor α mRNA and protein levels increased in the liver and epididymal adipose tissue of the obese and db/db mice fed BRS oil compared with HFD and standard diet, respectively. BRS oil might improve lipid metabolism by inhibiting lipogenesis and promoting fatty‐acid oxidation in HFD‐induced obese and db/db mice. 相似文献
84.
We investigated the ferroelectric switching dynamics as well as the multiferroic and piezoelectric properties of highly a-oriented epitaxial Bi5Ti3FeO15 (BTFO) thin films on Nb-doped SrTiO3 single crystal substrates. The BTFO thin films favored highly a-oriented crystallinity because c-oriented crystallinity decreased under deposition conditions in which substrate temperature and thin film deposition rate were simultaneously lowered. The highly a-oriented epitaxial BTFO thin films showed the best ferroelectric properties, whereas the highly c-oriented epitaxial BTFO thin films showed the best ferromagnetic properties. In particular, the BTFO thin films in which a- and c-oriented crystallinity were properly mixed showed the best piezoelectric properties. 相似文献
85.
Chung-Kyun Park Dong-Kwon Keum Pil-Soo Hahn 《Korean Journal of Chemical Engineering》1995,12(4):428-435
A stochastic model for the calculation of flow and contaminant transport in a single fracture with variable apertures was
presented. The spatially varying apertures of the fracture were generated using a geostatistical method, based on a given
aperture probability density distribution and a specified spatial correlation length. Fluid flowed between two points in the
fracture plane. The fluid potential at each node of the discretization mesh was computed and the steady state flow rates between
all the nodes were obtained. Then the contaminant transport was calculated using a particle tracking method. The migration
plumes of contaminant between the inlet and the outlet were displayed in contour plots and contaminant elution profiles were
also plotted. Calculations showed that fluid flow occured predominantly in a few preferred paths. Hence, the large range of
apertures in the fracture gives rise to flow channeling. Simulation results were correlated with the basic input parameters:
standard deviation of a lognormal aperture distribution function and the spatial correlation length. 相似文献
86.
Dong‐Yong Shin Jong‐Kwan Woo Yongtaek Hong Keum‐Nam Kim Do‐Ik Kim Myoung‐Hwan Yoo Hye‐Dong Kim Suhwan Kim 《Journal of the Society for Information Display》2009,17(9):705-713
Abstract— Early loss of image uniformity has been a critical drawback of active‐matrix organic light‐emitting‐diode (AMOLED) displays operated in time‐ratio gray‐scale mode. This problem is addressed with an analog calibration technique which measures the voltage across each OLED for a given current and subsequently controls the supply voltage of pixels and the voltage drop across the driving th in‐film transistor (TFT) of each OLED. The uniformity of test cells, which were aged to produce image sticking in a chessboard pattern, were improved. A measure of image sticking, called the extracted image‐sticking value (EISV), was formulated, which is developed and used for the quantitative evaluation of the calibration method. OLED voltages over a range of about 0.35 V were compensated to produce more uniform OLED currents than those before aging. The variation of luminance associated with image sticking was reduced by about 40% for a full‐white image after between 2 and 10 hours of accelerated aging with a constant voltage of 8 V across an OLED. 相似文献
87.
Jung Wook Kim Heun Park Geumbee Lee Yu Ra Jeong Soo Yeong Hong Kayeon Keum Junyeong Yoon Min Su Kim Jeong Sook Ha 《Advanced functional materials》2019,29(50)
The facile fabrication of thin and foldable self‐healing electronics on a poly(vinyl alcohol)/cellulose nanocrystal (PVA/CNC) composite film is reported. The self‐healing property of the PVA/CNC nanocomposite film can be activated by spraying water on the film surface, via dynamic formation of hydrogen bonding. The self‐healing efficiency of PVA/CNC is influenced by the content of CNC in the film, pH of the spraying solution, and the temperature. Via vacuum filtration and pattern transfer techniques, both a supercapacitor and a temperature sensor are fabricated on the same PVA/CNC film using gold nanosheet (AuNS) and polyaniline/multiwalled nanotube (PANI/MWCNT) electrodes. The fabricated supercapacitor with a gel‐type electrolyte exhibits a high electrochemical performance, and the thermoresistive temperature sensor shows a linear sensitivity with a fast response. Both devices exhibit superior mechanical stability and self‐healing property over 100 repetitive folding and five repetitive healing cycles, respectively, retaining the device performance owing to the percolated network of the conductive materials. This work demonstrates that our paper‐like thin PVA/CNC film‐based self‐healable devices can serve as highly durable and deformable electronics with longevity. 相似文献
88.
Hanchan Lee Gyusung Jung Kayeon Keum Jung Wook Kim Hyein Jeong Yong Hui Lee Dong Sik Kim Jeong Sook Ha 《Advanced functional materials》2021,31(50):2106491
Among the extensive development of wearable electronics, which can be implanted onto bodies or embedded in clothes, textile-based devices have gained significant attention. For daily basis applications, wearable energy storage devices are required to be stable under harsh environmental conditions and different deformational conditions. In this study, a textile-based stretchable supercapacitor with high electrochemical performance, mechanical stability, and temperature tolerance over a wide temperature range is reported. It exhibits high areal capacitances of 28.0, 30.4, and 30.6 mF cm−2 at −30, 25, and 80 °C, respectively, while the capacitance remains stable over three repeated cycles of cooling and heating from −30 to 80 °C. The supercapacitor is stable under stretching up to 50% and 1000 repetitive cycles of stretching. A temperature sensor and an liquid-crystal display are simultaneously driven at temperatures between −20 and 80 °C by the supercapacitors. The supercapacitors are woven into a nylon glove power a micro-light-emitting diode stably regardless of the bending of the index finger. Furthermore, the encapsulated supercapacitors retain the capacitance during being immersed in water for a few days. This study demonstrates the potential application of the fabricated supercapacitor as a wearable energy storage device that works under extreme temperature variations, high humidity, and body movements. 相似文献
89.
The objective of this study was to evaluate the status of the markers related to inflammation in db/db mice fed black raspberry seed (BRS) oil, which is rich in α‐linolenic acid. Mice were divided into four groups: (1) C57BL/6 mice fed 16 % calories from soybean oil (normal CON); (2) C57BL/KsJ‐db/db mice fed 16 % calories from soybean oil (CON); (3) C57BL/KsJ‐db/db mice fed 8 % calories from soybean and 8 % calories from BRS oil (BRS 50 %); and (4) C57BL/KsJ‐db/db mice fed 16 % calories from BRS oil (BRS 100 %). After 10 weeks, n‐6/n‐3 fatty acid ratios were significantly (P < 0.05) lower in the livers and epididymal adipose tissues of the BRS 50 % and BRS 100 % mice than in the CON. Serum TNFα and IL‐6 were significantly (P < 0.05) lower in the BRS 50 % and BRS 100 % than in the CON. Serum IL‐10 was significantly (P < 0.05) higher in the BRS 100 % than the CON. In the liver and epididymal adipose tissue, mRNA levels of pro‐inflammatory markers in the BRS 50 % and BRS 100 % were lower than in the CON. Anti‐inflammatory markers were higher in the epididymal adipose tissues of the BRS 50 % and BRS 100 % than in the CON. In the epididymal adipose tissue, macrophage infiltration markers (F4/80 and CD68) and leptin mRNA were significantly (P < 0.05) lower in the BRS 50 % and BRS 100 % than in the CON. Results of this study suggest that BRS oil may have anti‐inflammatory effects in obese diabetic mice by ameliorating inflammatory responses. 相似文献
90.
DaeJin Kim Dongyi Seo Seong-Woong Kim SeungEon Kim DongYeop Keum JaeKeun Hong 《Oxidation of Metals》2016,86(5-6):417-430
For this study, several TiAl–Nb–Si-based alloys were designed for a ductility improvement, whereby the high-temperature strength and oxidation resistance were not sacrificed. The environmental properties under the cyclic oxidation behaviors of the TiAl alloys were evaluated at 900 °C for up to 360 cycles. The compositions of the as-cast alloys determined their microstructures, and the cyclic oxidation behavior of the selected alloy was relatively comparable to that of a commercial TiAl alloy that is currently used in automotive engines. 相似文献