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961.
U. B. Azimov E. A. Roziboyev K. S. Kim D. S. Jeong Y. G. Lee J. E. Yun 《International Journal of Automotive Technology》2008,9(5):523-534
In this study, a visual investigation of sprays and flames is performed, and soot formation in Diesel-GTL fuel blends is studied
in a specially designed quiescent constant-volume chamber under various ambient gas temperatures and O2 concentrations. Similar to the case of soot formation during diesel fuel combustion, the sooting zone during the mixing-controlled
combustion of Diesel-GTL blends is located in the leading portion of the jet boundaries. Auto-ignition delay and soot concentration
decrease with an increase of GTL content in the fuel blend. Soot also decreases with lower O2 concentration, higher injection pressure, and lower ambient gas temperature. The lack of soot formation at lower O2 concentrations and lower temperatures suggests that Diesel-GTL fuel blends can be successfully utilized in low-temperature
diesel combustion technologies that are currently being developed. Furthermore, this mixing controlled combustion method with
Diesel-GTL blends can be used to modulate various engine operation parameters, and therefore to simultaneously reduce the
formation of soot and NOx within a wide range of diesel engine loads. 相似文献
962.
The need for the unmanned ground combat vehicle (UGCV), which is used for the surveillance, reconnaissance and targeting during
extremely dangerous condition on the battlefield, has steadily increased, and the transition from manned ground combat vehicles
to unmanned ground combat vehicles is expected to reduce the loss of lives during battle. The UGCV needs many types of capabilities
to achieve satisfactory performance. This paper focuses on the modeling and control of the power system of the UGCV, and proposes
the fuel cell hybrid system (FCHS) for the power system of the UGCV. The fuel cell hybrid system has many advantages in stealth
drive and the system efficiency. In addition, the FCHS is much quieter than the engine generator and generates much less heat.
The benefits of the FCHS are advantageous for use in Army operations, which require ‘silent watch’ capability and the ability
to operate without showing up on an enemy’s radar screen. The FCHS has a fuel cell and uses an energy storage system (ESS)
as a power source. The ESS (e.g., batteries or ultracapacitors) helps the fuel cell supply power to the electric drive system
and also recovers energy during deceleration. The ESS makes it possible to improve the efficiency and dynamic characteristic
of the power system. In this paper, the FCHS is composed of different combinations of component models. The component sizes
are chosen to satisfy performance requirements. In order to determine the power distribution between the fuel cell and the
ESS, a power management strategy based on the required power and the SOC (state of charge) of the ESS is proposed. Batteries
and ultracapacitor, components of the ESS, have different characteristics. Accordingly, varying the combination of ESS components
can change the performance of the power system. The performance of the FCHS with respect to different combinations of ESS
is analyzed using simulated results. 相似文献
963.
A robust H
∞ preview control is investigated for an active suspension system with look-ahead sensors. The uncertain system is described
by a state-space model with linear nominal parts and additional nonlinear time-varying norm-bounded uncertainties. Proof of
robust stability and a feedback-type robust H
∞ preview controller are derived by augmenting the dynamics of the original system and previewed road input. As, however, the
augmented previewed road input gives the system a much larger dimension than the original system, much more computation time
is required for solving of Riccati equations. To resolve this problem, a decomposed robust H
∞ preview controller is proposed. Robust stability and performance variations for system uncertainties are shown using a numerical
example of a quarter-car model. 相似文献
964.
Y. S. Pyoun H. T. Kim Y. C. Lee A. Gafurov H. Kim D. H. Jung 《International Journal of Automotive Technology》2008,9(1):61-70
Surface topology, cone angle and the forces acting on the cone of the clutch type limited slip differential (LSD) are major
design parameters for the bias ratio and the noise condition. Therefore much research has been dedicated to these developments
but the results have been used to submit patents. A new cone type limited slip differential for sport utility vehicles and
recreational vehicles, which has a very simple structure and easy compliance with the vehicle performance, has been developed
by the axiomatic approach and the ultrasonic nano crystal surface modification (UNSM) technology. The design criteria and
optimal value of the design parameters are determined by the axiomatic approach utilizing CAE tools. Test methodologies in
a test rig and in a vehicle were also developed. Test results showed good performance of bias ratio and noise level but durability
is still under testing. This study is an extension of F2006P266, FISITA 2006. 相似文献
965.
T. H. Hwang K. Park S. -J. Heo S. H. Lee J. C. Lee 《International Journal of Automotive Technology》2008,9(1):17-27
The performance of most electronic chassis control systems in the past has been optimized individually. Recently, a great
research effort has been dedicated to the integration of chassis control systems in an effort to improve the vehicle performance.
This involves orchestration of individual control modules so that they can jointly contribute to the enhancement of their
control effect. In this research, two integrated control logics for AFS (Active Front Steering) and ESP (Electronic Stability
Program) have been developed. Of the two logics, one uses a supervisor that rules over the individual modules. The other logic
uses a CL (Characteristic Locus) method, which is a frequency-domain multivariable control technique. The two logics have
been tested under various driving conditions to investigate their control effects. The results indicate that the proposed
integrated control logics can yield vehicle performance that is superior to that of the individual control modules without
any integration scheme. 相似文献
966.
S. J. Lee S. J. Jeong W. S. Kim C. B. Lee 《International Journal of Automotive Technology》2008,9(6):659-670
The use of a diesel particulate filter (DPF) in a diesel aftertreatment system has proven to be an effective and efficient
method for removing particulate matter (PM) in order to meet more stringent emission regulations without hurting engine performance.
One of the favorable PM regeneration technologies is the NO2-assisted regeneration method due to the capability of continuous regeneration of PM under a much lower temperature than that
of thermal regeneration. In the present study, the thermal behavior of the monolith during regeneration and the conversion
efficiency of NO2 from NO with an integrated exhaust system of a diesel oxidation catalyst (DOC) and DPF have been predicted by one-channel
numerical simulation. The simulation results of the DOC, DPF, and integrated DOC-DPF models are compared with experimental
data to verify the accuracy of the present model for the integrated DOC and DPF modeling. The effects of catalyst loading
inside the DOC and the volume ratio between the DOC and DPF on the pressure drop, the conversion efficiency, and the oxidation
rate of PM, have been numerically investigated. The results indicate that the case of the volume ratio of ‘DOC/DPF=1.5’ within
the same diameter of both monoliths produced close to the maximum conversion efficiency and oxidation rate of PM. Under the
engine operating condition of 175 kW at 2200 rpm, 100% load with a displacement of 8.1, approximately 55 g/ft3 of catalyst (Pt) loading inside the DOC with the active Pt surface of 5.3 m2/gpt was enough to maximize the conversion efficiency and oxidation rate of PM. 相似文献
967.
C. Oh Y. S. Kang Y. Youn A. Konosu 《International Journal of Automotive Technology》2008,9(2):191-196
Pedestrian-related accidents are considered to be the most serious of traffic accidents due to the associated high fatality
rates. In Korea, pedestrian fatalities accounted for approximately 40% of all traffic-related fatalities in 2004. Significant
efforts have been made to develop effective countermeasures for pedestrian-vehicle collisions. A basis for devising such countermeasures
is to understand the characteristics of pedestrian-vehicle collisions. This study develops a pedestrian fatality model capable
of predicting the probability of fatality in pedestrian-vehicle collisions. Binary logistic regression and a probabilistic
neural network (PNN) are employed to estimate the probability of pedestrian fatality. Pedestrian age, vehicle type and collision
speed are used as independent variables of the fatality model. The models developed herein are valuable tools that can be
used to direct safety policies and technologies associated with pedestrian safety. 相似文献
968.
Inconsistent choices in Stated Choice data;Use of the logit scaling approach to handle resulting variance increases 总被引:2,自引:0,他引:2
The scaling approach is a statistical estimation method that allows for differences in the amount of unexplained variation in different types of data, which can then be used together in the analysis. This approach has been mostly used in context of combining Stated Preference and Revealed Preference data, but has also been used as a method of identifying systematic differences in the variance of choices within a single Stated Preference data set, e.g. for investigation of learning and fatigue effects. This paper investigates whether a scaling approach is suitable for handling inconsistencies in Stated Choice data. Both the number of inconsistent choices, based on a test of violations of the transitivity axiom, and education are used as scaling variables. Scaling effects appear to exist due to inconsistent choices, and the amount of unexplained variance is shown to increase as the number of inconsistent choice increase. Scaling due to inconsistencies significantly improves the models and reduces the valuations of travel time. In addition, the scaling approach makes the valuations of travel time from the Stated Choice data more consistent with the valuations from Contingent Valuation data included in the same study. In spite of the fact that education is the only significant explanatory variable for the number of inconsistent choices, scaling due to education gives no significant improvement in the model. 相似文献
969.
The early warning of incidents on urban arterial roads in a congested city can reduce delay, accidents and pollutant emission. Freeway incident detection systems implemented in recent years may not be suitable for arterial incidents. Arterial incident detection is more difficult. The traffic flow on an arterial road is not conserved from the upstream end of a road link to the downstream end because urban traffic does turn in and out of side‐streets, car‐parks and local residences. Roadside friction such as kerbside parking and shopping traffic also tends to create apparent incidents which are in fact frequent and normal events. This paper develops a definition for an arterial incident and describes a case study on an arterial road in Melbourne, Australia. The study shows that detectors upstream of an incident are more useful for incident detection than downstream detectors. It also identifies occupancy and speed as the appropriate parameters to characterise and detect arterial incidents. 相似文献
970.
Taek S. Jang Hang S. Choi Takeshi Kinoshita 《Journal of Marine Science and Technology》2000,5(3):107-111
For a given velocity distribution around a hydrofoil, the inverse problem of the hydrofoil is studied. The inverse problem
is formulated by representing the hydrofoil in terms of vortices within the framework of linear potential theory. From the
mathematical formulation, it is known that the inverse problem turns out to be ill-posed in the usual topology. In this paper,
iterative and noniterative regularizations are applied to solve the problem and to find their suitability for the two-dimensional
inverse hydrofoil problem. Numerical experiments demonstrate that the regularization methods are accurate and suitable for
the inverse mathematical formulation for a given velocity distribution around a hydrofoil.
Received: June 6, 2000 / Accepted: December 8, 2000 相似文献