全文获取类型
收费全文 | 99篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 20篇 |
机械仪表 | 3篇 |
建筑科学 | 4篇 |
矿业工程 | 1篇 |
能源动力 | 5篇 |
轻工业 | 9篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 15篇 |
一般工业技术 | 12篇 |
冶金工业 | 12篇 |
自动化技术 | 13篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2019年 | 2篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 6篇 |
2004年 | 1篇 |
2002年 | 1篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有101条查询结果,搜索用时 15 毫秒
1.
2.
Su-Khiong Yong Chia-Chin Chong Geza Kolumbán 《International Journal of Wireless Information Networks》2007,14(2):121-131
The requirements of low cost, low power and longer operation range for low-rate wireless personal area network (LR-WPAN) applications
has driven the utilization of non linear communication approach. In this paper, a combined ultra-wideband (UWB) and chaotic
communication technologies is proposed to meet these challenging demands. Among the candidates, the differential chaos shift
keying (DCSK) modulation appears to be a very promising solution. The DCSK is a family of transmit reference (TR) system where
a correlator based receiver is used to demodulate the received signal. However, this is not very well understood in the literature
and therefore we will exemplify this issue in terms of noise performance. Furthermore, the feasibility study of the proposed
DCSK is presented through the scalability and link budget analysis in two different operation modes. The system performance
in both additive white Gaussian noise (AWGN) channel and standardized IEEE 802.15.4a UWB multipath channels are provided in
order to further demonstrate the capability of the proposed system. 相似文献
3.
Torsional interactions encountered with series compensated transmission lines are due to the negative damping effect of subsynchronous frequency currents induced by rotor oscillations. Methods of controlling these currents have appeared in the literature, however, this paper offers an alternative scheme based on enhancing the supersynchronous currents associated with positive damping. This results in cancellation of the negative electrical damping at the mechanical resonant frequency. The countermeasure consists of a passive shunt device connected at the generator terminals and tuned to the proper resonant frequency. The operating principle and design considerations are discussed and the effectiveness of the scheme is demonstrated. 相似文献
4.
Prediction of ring crack initiation in ceramics and glasses using a stress–energy fracture criterion
Roman Papšík Oldřich Ševeček Éric Martin Raúl Bermejo 《Journal of the American Ceramic Society》2023,106(7):4329-4342
Crack initiation in brittle materials upon spherical indentation is associated with the tensile radial stresses during loading. However, location of crack onset often differs (offset) from the site of maximal stress. In addition, experiments reveal a strong dependency of crack initiation forces on geometrical parameters as well as the surface condition of the sample. In this work, a coupled stress–energy fracture criterion is introduced to describe the initiation of ring cracks in brittle materials, which takes into account the geometry of the contact and the inherent strength and fracture toughness of the material. Several experiments reported in literature are evaluated and compared. The criterion can explain the location offset of the ring crack upon loading, as observed in various ceramics and glasses. It also predicts the ring crack initiation force upon contact loading, provided that surface compressive stresses, introduced during grinding or polishing processes, are taken into account. Furthermore, the stress–energy criterion may be employed to estimate the surface residual stress of ceramic parts, based on simple contact damage experiments. 相似文献
5.
Iulian Zoltan Boboescu Vasile Daniel Gherman Ion Mirel Bernadett Pap Roland Tengölics Gábor Rákhely Kornél L. Kovács Éva Kondorosi Gergely Maróti 《International Journal of Hydrogen Energy》2014
Biohydrogen production from synthetic wastewater as substrate was studied in anaerobic small scale batch reactors. Enriched anaerobic mixed consortia sampled from various environments were used as parent inocula to start the bioreactors. Selective enrichments were achieved by various physical and chemical pretreatments and changes in the microbial communities were monitored by metagenomic and molecular diagnostics approaches. Experimental data showed the feasibility of biohydrogen production using synthetic wastewater as substrate. The hydrogen generation capability of the different mixed consortia is clearly dependent on the pretreatment methods. The described approach opens the possibility for an alternative way towards simultaneous wastewater treatment and renewable energy generation. 相似文献
6.
7.
Due to the worldwide energy crisis, research and development activities in the field of renewable energy have been considerably increased in many countries. In Germany, wind energy is becoming particularly important. Although considerable progress has already been achieved, the available technical design is not yet adequate to develop reliable wind energy converters for conditions corresponding to low wind speeds and urban areas. The Savonius turbine appears to be particularly promising for such conditions, but suffers from a poor efficiency. The present study considers a considerably improved design in order to increase the output power of a Savonius turbine with either two or three blades. In addition, the improved design leads to a better self-starting capability. To achieve these objectives, the position of an obstacle shielding the returning blade of the Savonius turbine and possibly leading to a better flow orientation toward the advancing blade is optimized. This automatic optimization is carried out by coupling an in-house optimization library (OPAL) with an industrial flow simulation code (ANSYS-Fluent). The optimization process takes into account the output power coefficient as target function, considers the position and the angle of the shield as optimization parameters, and relies on Evolutionary Algorithms. A considerable improvement of the performance of Savonius turbines can be obtained in this manner, in particular a relative increase of the power output coefficient by more than 27%. It is furthermore demonstrated that the optimized configuration involving a two-blade rotor is better than the three-blade design. 相似文献
8.
Gerlinde Rusu Nicolas Joly Geza Bandur Ionel Manoviciu Patrick Martin Lucian Rusnac 《Journal of Polymer Research》2011,18(6):2495-2504
New inulin-based materials were obtained by graft-copolymerization of inulin (poly-β(1 → 2)-fructoside) with 2-ethyl-hexyl
acrylate. Inulin mixed esters were first synthesized by acylation using methacryloyl and palmitoyl chlorides. Further, these
esters were copolymerized with 2-ethyl-hexyl acrylate in order to obtain bio-based crosslinked materials that could be used
as commodity plastics and that would have biodegradable properties. The obtained products were characterized using FT-IR and
1H NMR spectroscopies, thermogravimetry; differential scanning calorimetry, and activation energy for the degradation processes
(using Kissinger method) was calculated. These biomaterials were also subjected to density measurement, tensile and torsion
tests to evaluate their mechanical properties. 相似文献
9.
Circulatory consequences of cardiac arrhythmias are not always evident. Proper interpretation of the clinical symptoms in certain cases requires assessment of the patients' other hemodynamic characteristics. The authors present the case of a patient with left ventricular hypertrophy, who developed severe circulatory failure at the time of artrioventricular dyssynchrony in association with junctional rhythm. Analogy between the circulatory consequences of the junctional rhythm and ventricular pacing was documented by hemodynamic measurements. The patient was subsequently treated by implanting an atrioventricular pacemaker. 相似文献
10.
V Balgha L Topa K Simon I Gál L Flautner A Pap 《Canadian Metallurgical Quarterly》1997,138(22):1387-1391
Benign and malignant tumors of papilla Vateri are rare diagnoses in the endoscopic practice. Sixteen patients with benign and 22 cases of malignant tumors are presented. In all of them endoscopic cholangiopancreatography with or without papillotomy followed by biopsy and operation in 13 cases was performed. Biopsy confirmed the endoscopy in 71%. Adenomyosis, supposed by endoscopy was proved by repeated histology in only 2/9 cases although invasive component of the tumor was found in 3/9 patients at operation underlying precancerous nature of this entity. Among 5 cases of villous adenoma one developed malignant alterations during 4 years of follow-up. Biopsy was not more effective after papillotomy than without it, and 5-7 days of delay for recovery of thermic lesion did not ameliorate success rate of histology. For malignant diseases surgical therapy should be considered if staging of tumor and general condition of the patient permits. In unresectable cases endoscopic palliation (papillotomy or polypectomy with or without drainage) can increase survival. In patients with benign tumors operative endoscopy followed by regular ultra-sonography and endoscopy seems to be necessary. 相似文献