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21.
Traffic Volume Time-Series Analysis According to the Type of Road Use   总被引:2,自引:0,他引:2  
Problems related to highway traffic operation and congestion management can be alleviated with the use of modern intelligent transportation systems (ITSs). Advanced Traveler Information Systems (ATIS) is one of the emerging technologies that will help travelers plan routes and schedules of their trips so as to redistribute the traffic over the highway network. Such redistribution will try to maximize the use of available highway capacity. Collections of real-time data and short-term predictions of traffic volumes are among the critical needs of an ATIS. This article studies characteristics of different traffic volume time series. In particular, time-series analysis is applied to the prediction of daily traffic volumes. The daily traffic volume is estimated by using the previous 13 daily traffic volumes. The study involves a comparison of statistical and neural network techniques for time series analysis. The analysis is applied to different types of road groups according to the trip purpose and trip length distribution. It is hoped that this study will provide a better understanding of various issues involved in the short-term prediction of traffic volumes on different types of highways.  相似文献   
22.
Over the last decade, driver distractions, such as cell phone use and texting, have become a significant contributor to roadway crashes. Some states now have legislation that severely restricts or bans driver activities deemed distracting. However, many policies and engineered countermeasures are based on self-reported crash data. This raises the issue of potential bias and when not controlled for in analysis supporting policy decisions, can lead to poor allocation of public resources. This study explores the impact of self-reporting driver distraction on the likelihood estimates of the injury severity category of vehicle crashes. Using a two-step correction technique, the presence of bias is tested, when present corrected, and its impact is interpreted. The findings show that self-reporting bias is present in the national database, a database often used to help evaluate policy and engineering options, self-reporting bias understates the true effect of driver distraction on injury severity, and it is not uniform across injury categories. As a result, the forecast of potential savings of countermeasure policies or in-vehicle devices will be distorted leading to inefficient allocation of public resources.  相似文献   
23.
24.
An HPLC method is presented for the separation of doxycycline HC1 from its analogs. The method, employing on line U.V. detection allows separation and quantitative estimation of doxycycline HC1 when its analogs are present upto 1% w/w. By this method doxycycline HC1 powder and tablets were analysed  相似文献   
25.
3D hierarchical structures are reported based on graphene–nickel encapsulated nitrogen‐rich aligned bamboo like carbon nanotubes, which show not only high‐performance supercapacitance behavior but also a great robust cyclic stability. A facile synthesis route is developed of 2D nickel oxide decorated functionalized graphene nanosheets (2D‐NiO‐f:GNSs) hybrids and 3D nitrogen doped bamboo‐shaped carbon nanotubes (NCNTs) vertically standing on the functionalized graphene nanosheets (3D‐NCNT@f:GNSs) by using a thermal decomposition method. The chemical reduction and morphology‐dependent electrochemical response are investigated. The enhanced specific capacitance of 3D‐NCNT@f:GNSs as compared to that of 2D‐NiO‐f:GNSs suggests the synergistic effects and indicates the importance of energy storage and superior long‐term cycling performance that are achieved. This 3D‐NCNT@f:GNSs hybrid shows a remarkable cycling stability with a maximum power density of 12.32 kW kg−1 and maximum energy density of 109.13 Wh kg−1 due to the good connection of NCNT and f:GNSs. This unique 3D nano network architecture enables the availability of large surface areas of NCNT, thus endowing the nanohybrids with high specific capacitance and excellent reusability.  相似文献   
26.
Helicopter radar return analysis: Estimation and blade number selection   总被引:2,自引:0,他引:2  
The problem of helicopter parameter estimation and blade number selection is addressed. The parameters are estimated based on Maximum Likelihood methods and the corresponding Cramér-Rao bounds are derived. To avoid ambiguities in blade number estimation, we apply information theoretic criteria for blade number selection incorporating alternate penalty functions. We assume that a clutter filter essentially removes all of the clutter and also part of the signal returns, lowering the effective signal-to-noise-ratio. The fractional Fourier transform is used to separate the combined tail and main rotor signals into two different returns, allowing initial estimates of their corresponding rotor parameters. The proposed technique is validated by using returns from a helicopter observed experimentally with a pulse-Doppler radar.  相似文献   
27.
Pawan Tyagi 《Thin solid films》2011,519(7):2355-2361
Application of the economical metal oxide thin-film photovoltaic devices is hindered by the poor energy efficiency. This paper investigates the photovoltaic effect with an ultrathin tantalum oxide (TaOx) tunnel barrier, formed by the plasma oxidation of a pre-deposited tantalum (Ta) film. These ~ 3 nm TaOx tunnel barriers showed approximately 160 mV open circuit voltage and 3-5% energy efficiency, for varying light intensity. The ultrathin TaOx (~ 3 nm) could absorb approximately 12% of the incident light radiation in 400-1000 nm wavelength range; this strong light absorbing capability was found to be associated with the dramatically large extinction coefficient. Spectroscopic ellipsometry revealed that the extinction coefficient of 3 nm TaOx was ~ 0.2, two orders higher than that of tantalum penta oxide (Ta2O5). Interestingly, refractive index of this 3 nm thick TaOx was comparable with that of stochiometeric Ta2O5. However, heating and prolonged high-intensity light exposure deteriorated the photovoltaic effect in TaOx junctions. This study provides the basis to explore the photovoltaic effect in a highly economical and easily processable ultrathin metal oxide tunnel barrier or analogous systems.  相似文献   
28.
An Integrated program PEELFIT is reported for the Apple IIe microcomputer, which performs pharmacokinetic analysis for intravenous and first order absorption (oral or intramuscular) data. PEELFIT, written in basic language, uses plasma concentration and time for input. Upon the user's choice, it carries out non-linear regression on the data for curve fitting, according to a one or two compartment model. the curve fitting can be done with three weighting schemes. Parameters of the plasma concentration equations are obtained from the regression analysis and further, these are employed to calculate the relevant pharmacokinetic parameters. Finally, the percentage of dose absorbed (absorbable fraction) is calculated as a function of time. various known data were analysed with PEELFIT and the results obtained confirmed its accuracy.  相似文献   
29.
A walkdown of Zion Unit 2 was performed in May 1987 to verify the seismic adequacy of mechanical and electrical equipment required for hot safe shutdown. This was the first pilot walkdown performed under the SQUG guidelines. Draft Generic Implementation Procedures developed by SQUG were used by the three Seismic Review Teams to walkdown 159 pieces of equipment. Based on the walkdown, 118 pieces of equipment were found to be adequate and the remaining 41 pieces were classified as outliers. Seven of these 41 outliers were further verified by subsequent walkdown and 17 were verified by additional calculations. Anchorage repairs/improvements and minor field adjustments due to seismic interaction concerns resolved the remaining 17 cases. A trend analysis of the outliers was also performed to see if other safety-related equipment, outside the scope of SQUG, should be addressed for any shortcomings. Two trends were identified, one for the anchorage of shop fabricated instrument racks, and another for bracing of HVAC duct system supplying intake air to the diesel generators. Appropriate repairs were issued for all safety-related items affected by these trends.  相似文献   
30.
Nickel nanorods with diameters ranging from 5 to 10 nm, encapsulated inside the carbon nanotubes, are prepared using microwave plasma chemical vapor deposition. High-resolution transmission electron microscopy (HRTEM) studies reveal the perfect crystalline nature of the rods with d-spacing closely matching the (111) interplanar spacing of Ni. The (111) planes of the Ni nanorods are always aligned at 39.6 degrees with respect to the graphite planes of the nanotubes. The cosine component of the d-spacing along the direction of the graphite planes is found to be 1.6 A; exactly half the d-spacing between the graphite planes. The electron diffraction pattern shows clear spots corresponding to Ni structure. The field cooled and zero field cooled magnetization data reveal the reversibility of the magnetization of the Ni nanorods and show a blocking temperature of 195 K, which correspond to energy barrier of 0.4 eV/(V).  相似文献   
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