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241.
刺桐(泉州)是中世纪各大宗教之家,有着丰富的宗教遗存,其中以石刻为多,引起中外学者的浓厚兴趣。澳大利亚研究团多次造访泉州,对泉州的宗教石刻(主要是基督教石刻)进行详尽的考证。研究团成员刘南强教授首先对泉州宗教石刻存在的历史背景和收藏保护情况做了简要概述,重点介绍访问的成果主要是碑文的解读与译释情况。 相似文献
242.
填土速率对软土路基变形影响的数值分析 总被引:2,自引:0,他引:2
基于plaxis软件针对新建彭湖高速K41+200软土路堤建立有限元分析模型,并开展有限元数值计算。通过分析不同填土速率、不同填土间隔时间工况下该断面的稳定与变形情况,得出该断面施工中与工后的沉降变化,并比较在不同填筑速率下施工过程以及工后的沉降变化,论证填土速率对路基施工质量的影响。 相似文献
243.
通过力学分析与室内试验研究了各种夹层用于半刚性基层反射裂缝的防裂情况,结果表明ISAC复合夹层有着较好的防裂效果。采取复合夹层下面的基层埋设位移计和测缝计,上面的沥青混合料面层埋设应变计的方法对试验路段复合夹层的防裂情况进行了测试。振弦式测缝计的试验测定结果的线性关系稳定.能较好地反映路面基层预切缝在温度变化情况下的实际缝隙变化规律。铺设聚酯玻纤布ISAC复合夹层的预切缝2和采用玻纤格栅作为上层应变吸收层的预切缝4的测试结果表明,两者具有基本一致的缝隙张开量变化规律。两者都有着较好的抗裂效果。在较高温度下。采用玻纤格栅ISAC复合夹层的防裂效果优于聚酯玻纤布ISAC复合夹层。但低温情况下的防裂效果还有待于后续的测试。 相似文献
244.
245.
Fault detection method for electric parking brake (EPB) systems with sensorless estimation using current ripples 总被引:1,自引:0,他引:1
C. W. Lee H. B. Chung Y. O. Lee C. C. Chung Y. S. Son P. Yoon 《International Journal of Automotive Technology》2010,11(3):387-394
A fault detection method with parity equations is proposed in this paper. Due to its low cost implementation, the velocity
of the motor is not measurable in electric parking brake (EPB) systems. Therefore, residuals are not reliable when estimating
the motor velocity with a low-resolution encoder. In this paper, we propose a fault detection method with sensorless estimation
using current ripples that estimates the position and velocity of the motor by detecting periodical oscillations of the armature
current caused by rotor slots. In addition, this method can estimate the position and velocity of the motor with less computational
effort than a state observer. Moreover, the method is less sensitive to motor parameters than model-based estimation methods.
The effectiveness of this method is validated with experimental data, and the simulation results show that various faults
have their own residual patterns. Therefore, we can detect the presence of faults by monitoring the residual signals. 相似文献
246.
Pacejka’s tire model is widely used and well-known by the automotive engineering community. The magic formula describes the
brake force, side force and self-aligning torque in terms of the longitudinal slip and slip angle, plus several corrections.
This paper uses approximation theory to obtain different types of approximations to the magic formula: rational functions
(RA) resulting from the Remez algorithm, expansions in a series of Chebyshev polynomials (ACh), a series of Chebyshev rational
polynomials (ARChPs), a series of rational orthogonal functions (ORF) and a series of ARChPs that result from grade-1 ORFs.
The last expansion shows the fastest convergence and most effective computation. Jacobi rational polynomials can also be obtained
to complement this expansion and facilitate fine-tuning in specific areas of the error curve. This work is complemented by
obtaining the original rational approximations to the inverse tangent function, which take advantage of the curve symmetry
to reduce the computation load and provide models that include the influence of the vertical load. The convergence properties
of the development in series and the error values resulting from numeric examples for the three types of stress are shown.
The proposed final ARChP expressions show very low error (1%) compared to the original magic formula. They can be computed
20 times faster; they can be evaluated, derived and integrated analytically easily; and their coefficients can be obtained
from tests using common least-squares algorithms. 相似文献
247.
A. López J. Serrat C. Cañero F. Lumbreras T. Graf 《International Journal of Automotive Technology》2010,11(3):395-407
Detection of lane markings based on a camera sensor can be a low-cost solution to lane departure and curve-over-speed warnings.
A number of methods and implementations have been reported in the literature. However, reliable detection is still an issue
because of cast shadows, worn and occluded markings, variable ambient lighting conditions, for example. We focus on increasing
detection reliability in two ways. First, we employed an image feature other than the commonly used edges: ridges, which we
claim addresses this problem better. Second, we adapted RANSAC, a generic robust estimation method, to fit a parametric model
of a pair of lane lines to the image features, based on both ridgeness and ridge orientation. In addition, the model was fitted
for the left and right lane lines simultaneously to enforce a consistent result. Four measures of interest for driver assistance
applications were directly computed from the fitted parametric model at each frame: lane width, lane curvature, and vehicle
yaw angle and lateral offset with regard the lane medial axis. We qualitatively assessed our method in video sequences captured
on several road types and under very different lighting conditions. We also quantitatively assessed it on synthetic but realistic
video sequences for which road geometry and vehicle trajectory ground truth are known. 相似文献
248.
We investigated the effects of injection parameters such as injection pressure, ambient pressure, and ambient temperature
on spray characteristics. We calculated the turbulence occurring point (t
c
), defined as the time required to generate a vortex, and the deceleration point (t
b
), defined as the time when spray penetration begins to decelerate, to elucidate the breakup mechanism of the test injectors.
The spray velocity coefficient (Cv) was obtained to evaluate the spray characteristics. As the ambient pressure increases in the case of a slit injector, Cv decreases. We investigated the effects of nozzle tip shape according to injection pressure, ambient pressure, and fuel properties
on spray characteristics and provide a Cv value of 0.38 for the swirl injector with a spray angle of 60° and the slit injector under atmospheric conditions. The value
of Cv in the case of a slit injector was reduced by increasing the ambient pressure. Our results suggest that Cv of a swirl injector is constant regardless of changes in ambient pressure, injection pressure, and fuel properties. On the
other hand, Cv of a slit injector is altered by changes in ambient pressure. 相似文献
249.
D. Danardono K. S. Kim E. Roziboyev C. U. Kim 《International Journal of Automotive Technology》2010,11(3):323-330
A roller vane type liquefied petroleum gas (LPG) pump was developed for a liquid phase LPG injection (LPLi) engine. Most of
the LPG pumps used in the current LPLi engines are installed inside of the LPG tank, but this pump is intended to be installed
outside of the LPG tank to overcome the difficulty of fixing an in-tank pump. Because LPG has a low boiling point and high
vapor pressure, it usually causes cavitation in the pump and consequently deteriorates the flow rate of the pump. The purpose
of this work is to optimize the design of the roller vane pump in order to suppress cavitation and increase the fuel flow
rate by using a computational fluid dynamics (CFD) analysis. In order to achieve these goals, the intake port configuration
and the rotor of the roller vane pump were redesigned and simulated using STAR-CD code. Computation was performed for six
different models to obtain the optimized design of the roller vane pump at a constant speed of 2600 rpm and a constant pressure
difference between the inlet and outlet of 5 bar. The computation results show that an increased intake port cross-section
area can suppress cavitation, and the pump can achieve a higher flow rate when the rotor configuration is changed to increase
its chamber volume. When the inlet pressure difference is 0.1 bar higher than the fluid saturation pressure, the pump reaches
its maximum flow rate. 相似文献
250.