首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   127篇
  免费   8篇
电工技术   3篇
化学工业   30篇
金属工艺   14篇
机械仪表   2篇
建筑科学   4篇
能源动力   6篇
轻工业   8篇
水利工程   2篇
无线电   17篇
一般工业技术   18篇
冶金工业   14篇
原子能技术   3篇
自动化技术   14篇
  2024年   1篇
  2023年   2篇
  2022年   7篇
  2021年   3篇
  2020年   5篇
  2019年   7篇
  2018年   7篇
  2017年   8篇
  2016年   4篇
  2015年   6篇
  2014年   7篇
  2013年   6篇
  2012年   5篇
  2011年   9篇
  2010年   10篇
  2009年   6篇
  2008年   4篇
  2007年   5篇
  2006年   10篇
  2005年   4篇
  2004年   3篇
  2003年   1篇
  2002年   1篇
  2000年   1篇
  1998年   3篇
  1997年   4篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1988年   2篇
  1978年   1篇
排序方式: 共有135条查询结果,搜索用时 15 毫秒
81.
Little is known about the interactions of single nucleotide polymorphisms (SNPs) and overweight/obesity on blood pressure levels. The present study was undertaken to detect 10 lipid-related gene SNPs and their interactions with overweight/obesity on blood pressure levels. Genotyping of ATP-binding cassette transporter A1 (ABCA-1) V825I, acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) rs1044925, low density lipoprotein receptor (LDL-R) AvaII hepatic lipase gene (LIPC) −250G > A, endothelial lipase gene (LIPG) 584C > T, methylenetetrahydrofolate reductase (MTHFR) 677C > T, the E3 ubiquitin ligase myosin regulatory light chain-interacting protein (MYLIP) rs3757354, proprotein convertase subtilisin-like kexin type 9 (PCSK9) E670G, peroxisome proliferator-activated receptor delta (PPARD) +294T > C, and Scavenger receptor class B type 1 (SCARB1) rs5888 was performed in 978 normal weight and 751 overweight/obese subjects. The interactions were detected by factorial regression analysis. The genotypes of ACAT-1 AC, LIPC GA and AA, and SCARB1 TT; LDL-R A-A- and LIPC GA; and SCARB1 TT were interacted with overweight/obesity to increase systolic, diastolic blood pressure (SBP, DBP) and pulse pressure (PP) levels; respectively. The genotypes of ACAT-1 CC; ACAT-1 AA and CC were interacted with overweight/obesity to decrease SBP, PP levels (p < 0.01–0.001); respectively. The differences in blood pressure levels between normal weight and overweight/obese subjects might partly result from different interactions of several SNPs and overweight/obesity.  相似文献   
82.
83.
The integration of the Internet of Vehicles (IoV) in future smart cities could help solve many traffic-related challenges, such as reducing traffic congestion and traffic accidents. Various congestion pricing and electric vehicle charging policies have been introduced in recent years. Nonetheless, the majority of these schemes emphasize penalizing the vehicles that opt to take the congested roads or charge in the crowded charging station and do not reward the vehicles that cooperate with the traffic management system. In this paper, we propose a novel dynamic traffic congestion pricing and electric vehicle charging management system for the internet of vehicles in an urban smart city environment. The proposed system rewards the drivers that opt to take alternative congested-free ways and congested-free charging stations. We propose a token management system that serves as a virtual currency, where the vehicles earn these tokens if they take alternative non-congested ways and charging stations and use the tokens to pay for the charging fees. The proposed system is designed for Vehicular Ad-hoc Networks (VANETs) in the context of a smart city environment without the need to set up any expensive toll collection stations. Through large-scale traffic simulation in different smart city scenarios, it is proved that the system can reduce the traffic congestion and the total charging time at the charging stations.  相似文献   
84.
85.
A new iterative algorithm is proposed to improve the detection of dim stellar objects that are in the neighbourhood of a bright object, using short-exposure images. This method separates data functions into the primary bright object function, the neighbourhood system function, and the background function. This approach uses the principles of the Expectation-Maximization algorithm with the Gerchberg-Saxton phase retrieval algorithm to overcome the image degradation caused by the photon counting noise from the charge-coupled devices and the turbulent atmospheric conditions. The performance of this new neighbourhood system algorithm is compared with that of the multiframe blind deconvolution algorithm, using laboratory data and computer-simulated data. This paper provides an improved technique to image closely spaced dim objects.  相似文献   
86.
Thermal desorption was used to study the behavioral particulars of the ion-implanted at 20 and 650°C helium in reactor ferrite-martensite EP-450, Eurofer-97, dispersion-hardened EP-450, Eurofer-97, and EK-164 austenitic steel. It is established that compared with the thermal desorption spectrum of EP-450 and Euroffer-97 steel the temperature interval for helium release from dispersion-hardened EP-450 and Eurofer 97 steels is wider for helium implantation at room temperature and especially at 650°C. In steel hardened by disperse oxides Y2O3, a substantial amount of helium is released at high temperatures after the main maximum in the thermal desorption spectrum as a result of the formation at the incoherent particle–matrix boundary of bubbles with high bonding energy with particles. In contrast to the ferrite-martensite steel irradiated in the temper state, the thermal desorption spectrum of EK-164 austenitic steel is more complex because of the multiple stage helium release due to the structural defects introduced by cold deformation.  相似文献   
87.
This paper presents a robust phase watermarking scheme for still digital images based on the sequency-ordered complex Hadamard transform (SCHT). The transform matrix of the SCHT exhibits sequency ordering which is analogous to frequency in the discrete Fourier transform (DFT). Hence, sequency-based image analysis can be performed for image watermarking while providing simple implementation and with less computational complexity for computation of the transform. As the SCHT coefficients are complex numbers which consist of both magnitudes and phases, they are suited to adopt phase modulation techniques to embed the watermark. In this proposed scheme, the phases of the SCHT coefficients in the sequency domain are altered to convey the watermark information using the phase shift keying (PSK) modulation. Low amplitude block selection (LABS) is used to enhance the imperceptibility of digital watermark, and amplitude boost (AB) method is employed to improve the robustness of the watermarking scheme. Spread spectrum (SS) technique is adopted to increase the security of watermark against various unintentional or intentional attacks. In order to demonstrate the effectiveness of the proposed watermarking scheme, simulations are conducted under various kinds of attacking operations. The results show that the proposed scheme is able to sustain a series of attacks including common geometric transformations such as scaling, rotating, cropping, painting, and common image-processing operations such as JPEG compression, low-pass filtering, sharpening, noising and phase perturbation, etc. Comparisons of the simulation results with the other schemes are also mentioned and the results reveal that the proposed scheme shows better robustness.  相似文献   
88.
An electrochemically integrated multi-electrode system namely the wire beam electrode (WBE) has been applied for the first time to study the effects of the transportation of electrochemically active species on the process, rate and pattern of electrochemical corrosion. The objective of this work is to demonstrate the applicability of the WBE method for investigating ion transportation related corrosion processes. A series of experiments have been carried out using WBEs made from mild steel and stainless steel wires. The WBE working surfaces were exposed to simulated diffusion-controlled corrosion environments where there were diffusion induced ions concentration gradients (termed diffusion-corrosion environment). Corrosion potential and current distribution maps (CPCD maps) were measured from WBE surfaces in continuous bases. Typical patterns have been identified from CPCD maps and the characteristics of these patterns have been found to depend heavily upon the type of electrode material and the type of corrosive ion. For mild steel WBE surface exposed to a diffusion-corrosion environment containing NiSO4 or FeCl3, the characteristic pattern in CPCD maps was found to emulate NiSO4 or FeCl3 concentration gradients, suggesting an ion-concentration controlled corrosion behaviour. However, when the mild steel WBE surface was exposed to a diffusion-corrosion environment containing NaCl, the characteristic pattern was found to show higher cathodic currents along the WBE edges with the magnitude decreasing in a contour-like manner towards the centre of the WBE surface, suggesting an oxygen concentration-controlled corrosion behaviour. When a stainless steel (SS316L) WBE surface was exposed to a diffusion-corrosion environment containing NiSO4 or NaCl, the corrosion pattern appeared to be mainly determined by the random distribution of weak sites in passive film. When the SS316L WBE was exposed to a diffusion-corrosion environment containing FeCl3, the CPCD map revealed a characteristic pattern that shows localised damage to passive film. This work demonstrates that the recognition and analysis of characteristic maps from WBE measurements can be used as a means of studying diffusion, migration and other forms of mass transportation related electrochemical corrosion processes.  相似文献   
89.
In an array of closely spaced magnetic islands as in patterned media, magnetostatic interactions play a major role in widening the switching field distribution and reducing the thermal stability. Patterned antiferromagnetically coupled (AFC) media provide interesting systems for studying the effect of magnetostatic interactions on the reversal of closely spaced AFC bits in an array, as AFC structure helps to reduce the remanent magnetization (M(r)), leading to reduced magnetostatic interactions. Here, we study the magnetic reversal of single domain-patterned AFC CoCrPt:oxide bilayer system with perpendicular magnetic anisotropy, by imaging the remanence state of the bits after the application of a magnetic field with magnetic force microscopy (MFM). The influence of magnetostatic fields from the neighboring bits on the switching field distribution (SFD) for an entity in a patterned media is studied by varying the stabilizing layer thickness of the AFC structure and bit spacing. We observe a distinct increase in stability and coercivity with an increase in stabilizing layer thickness for the 40 nm spaced bits. This demonstrates the effectiveness of the AFC structure for reducing magnetostatic interactions in patterned media, such that high thermal stability can be achieved by the reduced M(r), without writability issues.  相似文献   
90.
An effective technique for measuring the drag force on a solar concentrator in a subsonic wind tunnel with a simply-fabricated, low-cost force sensing mechanism is described. The measurement uncertainty was reduced by ensuring operation near full scale of the load sensor employed, and by averaging a large number of samples to reduce chance variations due to turbulent fluctuations in the system. The resulting drag coefficients from our apparatus successfully duplicated previously published experimental data from a geometrically-similar, parabolic trough style solar collector.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号