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191.
为研究抽水蓄能电站不同机组间同发同抽运行时的岔管水力特性,基于某抽水蓄能电站岔管的体型及设计参数,采用水动力模型对抽水蓄能电站同一水力单元内同发同抽等流量运行时的岔管段水力特性进行数值模拟研究。结果表明:研究范围内,同发同抽运行时岔管段水流会发生回流及低压区,最大的水头损失系数为0.5;与常规的运行工况相比,同一水力单元中进行同发同抽等流量运行时岔管内的水流流态会发生恶化、水头损失增大的现象,但从水力学的角度没有产生非常不良的流态。 相似文献
192.
为解决含风电互联电网中风功率预测与实际风功率之间存在的风功率偏差,以及负荷突增所造成的电网负荷频率波动的问题,研究并比较了现有解决方案,提出了一种干扰观测器与反馈控制器复合控制算法.该算法将风功率偏差以及负荷突增等视为集总干扰,设计干扰观测器估计集总干扰,并通过反馈控制器的设计抵消集总干扰的影响,并基于分离原理与线性矩阵不等式求取了观测器以及控制器设计参数,提出了算法定理并验证了稳定性.将所提算法与常用的比例积分微分(proportion intergration differentiation,PID)控制算法进行仿真比较,负荷控制算法对风功率偏差与负荷突增构成的集总干扰有着较强的抑制作用,且收敛速度更快,表现出较强的控制性能与鲁棒性.最后通过半物理实验进一步验证了所提算法的有效性与实用性. 相似文献
193.
针对传统正则匹配性能低下的问题,设计了基于多GPU的正则表达式匹配引擎,并采用折半分组优化算法解决了有限状态自动机在大规模正则集合情况下由于空间爆炸无法使用的问题,并做了相关的优化,提升了数据匹配速度.实验结果表明:基于多GPU的正则表达式匹配性能较CPU提升了61倍,其数据吞吐率远优于其他加速方式. 相似文献
194.
游车制动产生的动载荷是造成修井机井架振动冲击甚至过载失效的根源,针对制动特性与制动性能关系的研究有待深入。目前对修井机制动性能的研究多为基于单个零部件的摩擦分析,难以完全满足制动系统性能优化、评价的需要。以油田小修作业机制动系统为研究对象,基于刚体动力学理论研究不同制动特性对整机制动性能的影响,利用正交试验法分析不同工况下制动参数与制动性能的关系。研究发现:采用正矢制动特性时游车大钩制动加速度曲线优化明显,制动力矩增长率及最大制动力矩是影响制动性能的关键因素,因此正常制动力矩增长率控制在2000-3000N·m·s-1,最大制动力矩取15-20kN·m时,能满足现场制动时间与效率的最优解。 相似文献
195.
<正>The paper introduces the business-based interorganizational information platform(IOP) and analyzes the feasibility and mechanism of business-based IOP governing global supply chains vulnerability,and then aims to develop a risk evaluation software under reliable algorithm to appraise the capability of an interorganizational information platform resisting to global supply chains risks that supports platform users and providers to make decisions.The paper respectively starts with a basic conceptual model of global supply chains vulnerability and a conceptual model of global supply chains vulnerability in business-based IOP,and then gives the simulation model of governance of global supply chain vulnerability in business-based IOP;then has a discussion with the beneficial model of governing global supply chains vulnerability by using business-based IOP or not.The results of research:(1) If given the ratio of expense per income on global supply chains using business-based IOP, we can estimate the costs to take precautions against risks that decides to the maximum value of the average income of per transaction on global supply chains using business-based IOP.(2) If given total income of transaction on global supply chains using business-based IOP,we can estimate the maximum value of the ratio of expense per income on global supply chains using business-based IOP, which would help to make pricing policy for IOP service provider. 相似文献
196.
197.
一种迭代有序k最邻近距离实现数字图像特征点匹配的算法 总被引:1,自引:0,他引:1
方壮 《湖北民族学院学报(自然科学版)》2013,31(1):36-37,46
待配准图像和源图像之间具有自相似性或镜像关系时,SIFT特征匹配算法不能实现两幅图像特征点的正确匹配,针对这一问题,提出了一种通过dpk实现特征点正确匹配的迭代算法,在Matlab仿真实验中表明该算法能较好解决上述问题. 相似文献
198.
针对城市交通管理中的交通红绿灯计算机监控系统采用地埋感应线圈来识别红灯禁行区车辆的缺陷,描述在该计算机监控系统中如何采用视频移动侦测技术(VMD),取代地埋感应线圈来识别道路红灯禁区中行使的车辆,减少安置地埋线圈时对路面造成的损坏.分析应用该技术的可行性,硬件的可实现性.阐述如何通过计算机程序荻取摄相机自动抓拍的交通红绿灯路口上行驶的机动车的违章行使照片和道路交通状况信息的方法. 相似文献
199.
Estimation of wind erosion rates by using 137Cs tracing technique: A case study in Tariat-Xilin Gol transect, Mongolian Plateau 总被引:2,自引:0,他引:2
Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we established the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the 137Cs tracing technique and examined their spatial dynamics. Our results showed that the 137Cs inventories of sampling sites ranged from 265.63=44.91 to 1279.54=166.53 Bq. m-2, and the wind erosion rates varied from 64.58 to 419.63 t. km-2. a-~ accordingly. In the Mongolia section of the transect (from Tariat to Sainshand), the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect (Inner Mongolia), the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia. 相似文献
200.
Direct assimilation of satellite radiance data in GRAPES variational assimilation system 总被引:7,自引:3,他引:4
GuoFu Zhu JiShan Xue Hua Zhang ZhiQuan Liu ShiYu Zhuang LiPing Huang PeiMing Dong 《科学通报(英文版)》2008,53(22):3465-3469
Variational method is capable of dealing with observations that have a complicated nonlinear relation with model variables representative of the atmospheric state, and so make it possible to directly assimilate such measured variables as satellite radiance, which have a nonlinear relation with the model variables. Assimilation of any type of observations requires a corresponding observation operator, which establishes a specific mapping from the space of the model state to the space of observation. This paper presents in detail how the direct assimilation of real satellite radiance data is implemented in the GRAPES-3DVar analysis system. It focuses on all the components of the observation operator for direct assimilation of real satellite radiance data, including a spatial interpolation operator that transforms variables from model grid points to observation locations, a physical transformation from model variables to observed elements with different choices of model variables, and a data quality control. Assimilation experiments, using satellite radiances such as NOAA17 AMSU-A and AMSU-B (Advanced Microwave Sounding Unit), are carried out with two different schemes. The results from these experiments can be physically understood and clearly reflect a rational effect of direct assimilation of satellite radiance data in GRAPES-3DVar analysis system. 相似文献