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排序方式: 共有357条查询结果,搜索用时 140 毫秒
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针对视觉测量在轨道交通隧道大范围轮廓测量上的问题,研究设计一种大型多阵列圆标定板进行系统标定工作,提出区域生长重心法实现对标定图像上基准点的提取。即将区域生长法和灰度重心法相结合,通过粗定位寻找每个基准圆的种子点,考虑种子点像素的4邻域像素进行区域生长,然后利用灰度重心法提取生长区域的重心作为基准点。将非线性变化的基准点替代线性提取的基准圆的种子点,消除了图像畸变的影响,保证了特征检测过程的可靠性和鲁棒性,达到对于多阵列圆大型标定板基准点的提取。通过搭载鱼眼镜头拍摄6m的模拟隧道横断面轮廓,进行轮廓测量与还原。实验表明该方法提取的基准点像素坐标误差可达到2pixel以内,系统测量精度能够达到±5mm以内,完全满足轨道交通隧道横断面轮廓测量误差标准。 相似文献
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Wojciech P. Adamczyk ;Gabriel Wecel ;Marcin Klajny ;Pawet Kozolub ;Adam Klimanek ;Ryszard A. Biatecki 《Particuology》2014,(5):29-40
The constantly developing fiuidized combustion technology has become competitive with a conventional pulverized coal (PC) combustion. Circulating fluidized bed (CFB) boilers can be a good alternative to PC boilers due to their robustness and lower sensitivity to the fuel quality. However, appropriate engineering tools that can be used to model and optimize the construction and operating parameters of a CFB boiler still require development. This paper presents the application of a relatively novel hybrid Euler-Lagrange approach to model the dense gas-solid flow combined with a combustion process in a large-scale indus- trial CFB boiler. In this work, this complex flow has been resolved by applying the ANSYS FLUENT 14.0 commercial computational fluid dynamics (CFD) code. To accurately resolve the multiphase flow, the original CFD code has been extended by additional user-defined functions. These functions were used to control the boiler mass load, particle recirculation process (simplified boiler geometry), and interphase hydrodynamic properties. This work was split into two parts. In the first part, which is referred to as pseudo combustion, the combustion process was not directly simulated. Instead, the effect of the chemi- cal reactions was simulated by modifying the density of the continuous phase so that it corresponded to the mean temperature and composition of the flue gases, In this stage, the particle transport was simu- lated using the standard Euler-Euler and novel hybrid Euler-Lagrange approaches, The obtained results were compared against measured data, and both models were compared to each other. In the second part, the numerical model was enhanced by including the chemistry and physics of combustion. To the best of the authors' knowledge, the use of the hybrid Euler-Lagrange approach to model combustion is a new engineering application of this model, In this work, the combustion process was modeled for air-fuel combustion. The simulation results were compared with experimental data. 相似文献
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大型粮仓温度分布反演数学模型的研究 总被引:3,自引:0,他引:3
采用有限元数值模拟方法,以响应面模型RSM(Response surface model)理论为基础对大型粮仓冬、夏两季的温度分布进行了深入分析,推导了粮仓温度反演数学模型。将采集的温度值导入RSM模型中,并结合单因素轮换法、正交实验和统计方法,通过构造一个具有明确表达形式的多项式来预测粮仓温度分布反演数学模型。在数学模型的基础上给出各因子交互作用下的设计空间、各因素对粮温影响的主效应及交互效应。实验证明该数学模型误差小,精度高,具有良好的计算性能,在大型粮仓温度监控系统中采用该模型能够解决布线少、预测空间范围广的问题。 相似文献
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This paper extends Le van's work to the case of nonlinear problem and the complicated configuration. The wrinkling stress distribution and the pressure effects are also included in our analysis. Pseudo-beam method is presented based on the inflatable beam theory to model the inflatable structures as a set of inflatable beam elements with a prestressed state. In this method, the discretized nonlinear equations are given based upon the virtual work principle with a 3-node Timoshenko's beam model. Finite element simulation is performed by using a 3-node BEAM189 element incorporating ANSYS nonlinear program. The pressure effect is equivalent included in our method by modifying beam element cross-section parameters related to pressure. A benchmark example, the bending case of an inflatable cantilever beam, is performed to verify the accuracy of our proposed method. The comparisons reveal that the numerical results obtained with our method are close to open published analytical and membrane finite element results. The method is then used to evaluate the whole buckling and the loadcarrying characteristics of an inflatable support frame subjected to a compression force. The wrinkling stress and region characteristics are also shown in the end. This method gives better convergence characteristics, and requires much less computation time. It is very effective to deal with the whole load-carrying ability analytical problems for large scale inflatable structures with complex configuration. 相似文献
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锦屏一级水电站2#尾水调压室所处位置地质条件复杂,在桩号0+320°~0+360°和0+0°~0+120°之间开挖时局部掉块严重。本文综合分析后,提出了2#尾调室顶拱未开挖域产生大型不稳定块体的必要条件是:(1)由节理①④F183组结构面和开挖临空面切割产生;(2)块体大小主要取决于节理组①和④的延伸长度;(3)较大不稳定块体的产生区域,必然位于F18断层带下盘。对2#尾调室顶拱进行搜索预测,预测结果表明该潜在块体位于未开挖区域桩号0+180°~0+260°之间,规模约为50m3,重达133.5t。根据块体理论分析,其稳定性系数为1.052,处于临界状态,应采取相应的应急支护补强措施。 相似文献
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象山港潮间带大型底栖动物次级生产力初探 总被引:2,自引:0,他引:2
通过2006~2007年对象山港滩涂潮间带大型底栖动物春、夏、秋、冬的4次调查,利用Brey经验公式进行了大型底栖动物栖息丰度、生物量、次级生产力和P/B值的研究.结果表明:该海域年平均栖息丰度为680.2ind m-2;年平均生物量(以去灰干重计)为16.82g m-2;年平均次级生产力(以去灰干重计)为17.26g (m2 a)-1;P/B值为0.91~1.18a-1.由此得出象山港大型底栖动物次级生产力湾口和湾底大于湾中,这与象山港是一个深入内陆的半封闭狭长型海湾有关;P/B值从湾口到湾底依次升高,说明象山港湾口的大型底栖动物群落中个体小、生活史短、代谢快,湾底的大型底栖动物群落生活史较长,且物种组成基本稳定. 相似文献