全文获取类型
收费全文 | 14704篇 |
免费 | 773篇 |
专业分类
公路运输 | 4394篇 |
综合类 | 3705篇 |
水路运输 | 2826篇 |
铁路运输 | 4074篇 |
综合运输 | 478篇 |
出版年
2024年 | 57篇 |
2023年 | 116篇 |
2022年 | 286篇 |
2021年 | 445篇 |
2020年 | 499篇 |
2019年 | 303篇 |
2018年 | 257篇 |
2017年 | 329篇 |
2016年 | 332篇 |
2015年 | 457篇 |
2014年 | 1040篇 |
2013年 | 744篇 |
2012年 | 1349篇 |
2011年 | 1276篇 |
2010年 | 1026篇 |
2009年 | 964篇 |
2008年 | 945篇 |
2007年 | 1258篇 |
2006年 | 1125篇 |
2005年 | 785篇 |
2004年 | 490篇 |
2003年 | 334篇 |
2002年 | 233篇 |
2001年 | 212篇 |
2000年 | 130篇 |
1999年 | 100篇 |
1998年 | 74篇 |
1997年 | 68篇 |
1996年 | 40篇 |
1995年 | 28篇 |
1994年 | 35篇 |
1993年 | 44篇 |
1992年 | 20篇 |
1991年 | 17篇 |
1990年 | 20篇 |
1989年 | 22篇 |
1988年 | 13篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
191.
192.
193.
194.
195.
随着社会科技发展,对车辆智能化配置需求越来越强烈,面对日趋复杂的车门电子控制设计,新增一个功能就增加一个控制器的方式,不但增加了控制的复杂程度,整车线束也更加复杂,同时由于负载受限制,功能上无法做到多样化。故而国内外主机厂已经将分布式控制方式作为整车架构首选。文章采用左、右前门控制模块分别控制该侧车门上各种功能需求的控制方案,通过对模块的电源及信号采集硬件设计、软件系统架构及车窗防夹的软件设计方案,构建分布式控制方式,实现在提升整车性能的同时,达到有效降低整车成本的目标。 相似文献
196.
道路运输车辆达标车型的实施,有效提升了道路运输车辆的安全性能。文章主要从电子稳定性控制系统、车道偏离预警系统、前向碰撞预警系统、自动紧急制动系统四个整车主动安全测试项目对道路运输车辆达标车型相应标准进行介绍,为道路运输车辆达标车型相关从业人员提供了主动安全整车项目试验参考。 相似文献
197.
This paper investigates the function of doubly-fed asynchronous machine(DASM)with emphasis placed on its ability to the stabilization of the power system including wind generators.P(active power)and Q(reactive power)compensation from DASM can be regulated independently through secondary-excitation controlling.Simulation results by power system computer aided design(PSCAD)show that DASM can restore the wind-generator system to a normal operating condition rapidly even following severe transmission-line failures.Comparison studies have also been performed between wind turbine pitch control and proposed method. 相似文献
198.
A new passive wheel type of biped ice-skating robot(BISR)which was able to imitate human skating motion was developed. Firstly, the characteristics of two types of human skating gait were introduced; secondly, after simplifying the kinematical model, the BISR's motion principle was presented; then the construction and control system of BISR were proposed; at last, the skating experiment of the BISR in a symmetric gait mode was conducted and some conclusions were drawn. 相似文献
199.
Development of an Autonomous Flight Control System for Small Size Unmanned Helicopter Based on Dynamical Model 总被引:1,自引:0,他引:1
WANG Geng Kondak Konstantin Marek Musial SHENG Huan-ye LU Tian-sheng Hommel Günter 《上海交通大学学报(英文版)》2007,12(6):744-752
It is devoted to the development of an autonomous flight control system for small size unmanned helicopter based on dynamical model. At first, the mathematical model of a small size helicopter is described. After that simple but effective MTCV control algorithm was proposed. The whole flight control algorithm is composed of two parts: orientation controller based on the model for rotation dynamics and a robust position controller for a double integrator. The MTCV block is also used to achieve translation velocity control. To demonstrate the performance of the presented algorithm, simulation results and results achieved in real flight experiments were presented. 相似文献
200.
The eigenvector of a module with six adjacent module's state was constructed according to self-reconfigurable robot M-Cubes and the configuration of system was expressed with the eigenvectors of all modules.According to the configuration and motion characteristics of the modules,a 3-dimension motion rule set was provided.The rule sets of each module was run according to eigenvector of the module after the motion direction of system decided and motion rules were selected.At last,the rapid and effective motion and metamorphosis were realized in system.The rule sets are operated on three systems and the distributed motion of system is fully realized.The result of simulation shows that the 3-dimension motion rule sets has perfect applicability and extensibility.The motion steps and communication load of the modules increase with the module number in linear. 相似文献