首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   481篇
  免费   30篇
  国内免费   9篇
电工技术   9篇
综合类   14篇
化学工业   86篇
金属工艺   15篇
机械仪表   25篇
建筑科学   15篇
矿业工程   8篇
能源动力   12篇
轻工业   52篇
水利工程   2篇
石油天然气   29篇
无线电   33篇
一般工业技术   88篇
冶金工业   51篇
原子能技术   24篇
自动化技术   57篇
  2024年   3篇
  2023年   4篇
  2022年   5篇
  2021年   14篇
  2020年   13篇
  2019年   17篇
  2018年   23篇
  2017年   14篇
  2016年   17篇
  2015年   16篇
  2014年   23篇
  2013年   37篇
  2012年   18篇
  2011年   37篇
  2010年   24篇
  2009年   20篇
  2008年   18篇
  2007年   17篇
  2006年   17篇
  2005年   15篇
  2004年   15篇
  2003年   15篇
  2002年   8篇
  2001年   4篇
  2000年   8篇
  1999年   6篇
  1998年   10篇
  1997年   18篇
  1996年   13篇
  1995年   11篇
  1994年   4篇
  1993年   6篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1984年   4篇
  1983年   4篇
  1982年   2篇
  1981年   4篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1977年   3篇
  1976年   6篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1971年   1篇
  1906年   5篇
  1905年   1篇
排序方式: 共有520条查询结果,搜索用时 15 毫秒
1.
2.
Summary In this paper a new high efficiency C-O grid coupled with the potential flow solver based on the finite volume technique is given. It significantly reduces the CPU time and increases the computational efficiency. In order to improve the accuracy of traditional potential method a shock point operator is used to account for entropy correction. Some calculated results of 2D inviscid, viscous/inviscid interaction and 3D inviscid flow indicate that nonisentropic potential method produces results closer to Euler solution as well as experimental data, while its computational efforts are nearly the same as the usual isentropic potential method.With 9 Figures  相似文献   
3.
In this paper, some biparametric models for an elastic foundation are proposed. It is assumed that the foundation has the shape of the wedge. The modeling procedure starts from the linear elasticity equations into which we introduce some simplifying assumptions based on the conceptions of decay functions. The simplified models are described by the ordinary differential equations. Stationary and nonstationary Green’s functions for the foundation considered are obtained by applying the Hankel and Laplace transform methods. An example of the interaction between the rigid plate and the elastic wedge foundation is studied.  相似文献   
4.
We present a study of magneto-thermal instabilities in polycrystalline MgB2 superconductor, by magnetic hysteresis loop measurements and by investigations of magnetic flux dynamics with a miniature Hall probe. Temperature and magnetic field ranges where the flux jumps may be observed have been determined. On the basis of measurements of the magnetic flux dynamics, an average magnetic diffusivity describing the process of the flux jump is estimated. This parameter is compared with the thermal and magnetic diffusivities calculated on the basis of available data for thermal conductivity, heat capacity and resistivity. It is shown that the estimated value of the field of the first flux jump is influenced significantly by the field dependence of specific heat. In order to explain the observed phenomenon, the temperature reached by the sample during the flux jump at different magnetic fields is calculated.  相似文献   
5.
众所周知,2008年以来,由美国的次贷危机引发的全球性金融风暴,也很快波及到远在万里之外的中国。我国的金融、制造、建筑及服务等各行各业都受到了很大的影响,工程咨询行业也不例外。所谓国难兴邦,困境兴企,越是在危机的时候越要用更长远的眼光来审视全行业的发展。中咨协会2009年年会的主题是“应对金融危机挑战,提供可持续解决方案”,可以看出整个行业已经在进行深层次的思考——我们不仅要在“危机”中求发展,而且还要“可持续”的发展,要为咨询行业开辟一个健康的未来。  相似文献   
6.
基于流形学习的人体动作识别   总被引:5,自引:2,他引:3       下载免费PDF全文
目的 提出了一个基于流形学习的动作识别框架,用来识别深度图像序列中的人体行为。方法 从Kinect设备获得的深度信息中评估出人体的关节点信息,并用相对关节点位置差作为人体特征表达。在训练阶段,利用LE(Lalpacian eigenmaps)流形学习对高维空间下的训练集进行降维,得到低维隐空间下的运动模型。在识别阶段,用最近邻差值方法将测试序列映射到低维流形空间中去,然后进行匹配计算。在匹配过程中,通过使用改进的Hausdorff距离对低维空间下测试序列和训练运动集的吻合度和相似度进行度量。结果 用Kinect设备捕获的数据进行了实验,取得了良好的效果;同时也在MSR Action3D数据库上进行了测试,结果表明在训练样本较多情况下,本文方法识别效果优于以往方法。结论 实验结果表明本文方法适用于基于深度图像序列的人体动作识别。  相似文献   
7.
In this paper we consider robust stabilization of the class of nonlinear plants of the form $$\dot x = f(x) + \sum\limits_{i = 1}^m {g_i } (x)u_i (t),$$ which are equivalent, under smooth state space coordinate transformations and nonlinear state feedback, to controllable systems. This approach is very sensitive for unknown parameters' values. Parameter adaptation may be used as a technique to robustify minimum-phase systems [3]. We give an example of a locally stable adaptive tracking system in which the last assumption is weakened. The minimum-phase plant considered in the paper is a current-controlled squirrel cage induction motor.  相似文献   
8.
In metastatic breast cancer the goal to reach must be the best possible palliation with minimum discomfort for the patient. We reviewed our experience with radiotherapy (20 or 30 Gy), systemic therapy and brace. Among 2200 breast cancer patients, we extracted 28 potential candidates for resection. All of them developed new metastases outside the treated field within one year. Local control was achieved in 68%, and 80% of them had stable or better performance status at 3 months. From our analysis, even patients with a so called "solitary lesion" do not seem to have a better prognosis than others. We conclude that radiotherapy (with systemic therapy and a brace) is still first-choice treatment for vertebral metastases; CT-guided percutaneous biopsy can avoid worthless major operations. The role of surgery should be limited to neurological compression, severe mechanical instability and to salvage the failures of conservative treatment.  相似文献   
9.
A home-use device that allows rapid and quantitative sperm quality analysis is desirable but not yet fully realized. To aid this effort, this article presents a microfluidic device capable of quantifying sperm quality in terms of two critical fertility-related parameters—motile sperm concentration and motility. The microdevice produces flow field for sperms to swim against, and sperms that overcame the flow within a specified time are propelled along in a separate channel and counted via resistive pulse technique. Data are compared to two control methods clinically utilized for sperm quality exam—hemocytometer and the sperm quality analyzer. Results reveal the numbers of pulses generated by passage of sperms correlates strongly with the two control methods: pulse number from 0 to 335 corresponds to progressively motile sperm concentrations from 0 to 19 × 106/ml (hemocytometer) and Sperm Motility Index from 0 to 204 (sperm quality analyzer). The microdevice should be applicable to facilitate self-assessment of sperm quality at home.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号