全文获取类型
收费全文 | 7825篇 |
免费 | 990篇 |
国内免费 | 609篇 |
专业分类
电工技术 | 676篇 |
技术理论 | 2篇 |
综合类 | 1162篇 |
化学工业 | 764篇 |
金属工艺 | 233篇 |
机械仪表 | 614篇 |
建筑科学 | 735篇 |
矿业工程 | 383篇 |
能源动力 | 254篇 |
轻工业 | 267篇 |
水利工程 | 247篇 |
石油天然气 | 518篇 |
武器工业 | 111篇 |
无线电 | 505篇 |
一般工业技术 | 849篇 |
冶金工业 | 248篇 |
原子能技术 | 47篇 |
自动化技术 | 1809篇 |
出版年
2024年 | 11篇 |
2023年 | 86篇 |
2022年 | 188篇 |
2021年 | 211篇 |
2020年 | 259篇 |
2019年 | 264篇 |
2018年 | 244篇 |
2017年 | 255篇 |
2016年 | 331篇 |
2015年 | 323篇 |
2014年 | 424篇 |
2013年 | 514篇 |
2012年 | 569篇 |
2011年 | 559篇 |
2010年 | 426篇 |
2009年 | 453篇 |
2008年 | 447篇 |
2007年 | 528篇 |
2006年 | 471篇 |
2005年 | 423篇 |
2004年 | 338篇 |
2003年 | 283篇 |
2002年 | 302篇 |
2001年 | 244篇 |
2000年 | 175篇 |
1999年 | 160篇 |
1998年 | 171篇 |
1997年 | 122篇 |
1996年 | 132篇 |
1995年 | 102篇 |
1994年 | 85篇 |
1993年 | 56篇 |
1992年 | 60篇 |
1991年 | 36篇 |
1990年 | 30篇 |
1989年 | 33篇 |
1988年 | 16篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1961年 | 2篇 |
1956年 | 2篇 |
排序方式: 共有9424条查询结果,搜索用时 93 毫秒
61.
62.
In this paper, we discuss a loop transformation framework that is based on integer non-singular matrices. The transformations
included in this framework are called Λ-transformations and include permutation, skewing and reversal, as well as a transformation
calledloop scaling. This framework is more general than existing ones; however, it is also more difficult to generate code in our framework.
This paper shows how integer lattice theory can be used to generate efficient code. An added advantage of our framework over
existing ones is that there is a simple completion algorithm which, given a partial transformation matrix, produces a full
transformation matrix that satisfies all dependences. This completion procedure has applications in parallelization and in
the generation of code for NUMA machines.
This work was supported by the Cornell Theory Center, NSF Presidential Young Investigator award #CCR-8958543. by NSF Grant
#CCR-9008526, and by a grant from the Hewlett-Packard Company. 相似文献
63.
This study considers a flowshop type production system consisting of m machines. A material handling robot transports the parts between the machines and loads and unloads the machines. We consider the sequencing of the robot moves and determining the speeds of these moves simultaneously. These decisions affect both the robot’s energy consumption and the production speed of the system. In this study, these two objectives are considered simultaneously. We propose a second order cone programming formulation to find Pareto efficient solutions. We also develop a heuristic algorithm that finds a set of approximate Pareto efficient solutions. The conic formulation can find robot schedules for small cells with less number of machines in reasonable computation times. Our heuristic algorithm can generate a large set of approximate Pareto efficient solutions in a very short computational time. Proposed solution approaches help the decision-maker to achieve the best trade-off between the throughput of a cell and the energy efficiency of a material handling robot. 相似文献
64.
A reduced order model predictive control (MPC) is discussed for constrained discrete‐time linear systems. By employing a decomposition method for finite‐horizon linear systems, an MPC law is obtained from a reduced order optimization problem. The decomposition enables us to construct pairs of initial state and control sequence which have large influence on system responses, and it also characterizes the standard LQ control. The MPC law is obtained based on a combination of the LQ control and dominant input sequences over the prediction horizon. The proposed MPC method is illustrated with numerical examples. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
65.
66.
A normal mode analysis is presented and numerical tests are performed to assess the effectiveness of a new time-splitting algorithm proposed recently in Karniadakiset al. (1990) for solving the incompressible Navier-Stokes equations. This new algorithm employs high-order explicit pressure boundary conditions and mixed explicit/implicit stiffly stable time-integration schemes, which can lead to arbitrarily high-order accuracy in time. In the current article we investigate both the time accuracy of the new scheme as well as the corresponding reduction in boundary-divergence errors for two model flow problems involving solid boundaries. The main finding is that time discretization errors, induced by the nondivergent splitting mode, scale with the order of the accuracy of the integration rule employed if a proper rotational form of the pressure boundary condition is used; otherwise a first-order accuracy in time similar to the classical splitting methods is achieved. In the former case the corresponding errors in divergence can be completely eliminated, while in the latter case they scale asO(vt)1/2. 相似文献
67.
68.
针对风电和电热负荷不确定的问题,提出计及源荷不确定性的旋转备用容量的优化方法,建立考虑电热备用耦合影响的调度模型。在日前阶段,以能源与负荷的预测量制定机组的出力方案,风电由于其预测精度较低,利用Beta概率密度函数来拟合风电出力,从而确定风电的不确定性带来的旋转备用容量,利用机会约束规划来处理不确定问题;负荷有较高的预测精度,但其波动性较强,使用概率场景生成和削减的方法制定不同场景下负荷备用需求的调整量,以日运行成本最低建立目标函数,运用改进的粒子群算法在IEEE30节点系统上验证了所提模型的经济性和鲁棒性。 相似文献
69.
针对块对角表示(block diagonal representation, BDR)子空间聚类算法在对子空间重叠的高维数据聚类时效果较差的问题,提出成对约束的块对角子空间聚类(constrained subspace clustering with block diagonal representation, CBDR)算法,设计主动式学习策略,获取用户提供的少量数据点成对信息,以改进BDR算法的性能,给出CBDR算法的目标函数和求解过程。在测试集上的试验结果表明,CBDR算法的聚类错误率和归一化互信息指标比BDR和SBDR(structured block diagonal representation)算法好,而且主动式选取点对方法优于随机选取点对方法,使用少于5‰的约束信息可降低BDR的聚类错误率达到5%以上。 相似文献
70.
在能源互联网和低碳背景下,提出一种考虑需求侧管理(demand side management, DSM)和碳交易的电-气互联网络分散式低碳经济调度模型。首先,根据碳交易市场的实际情况建立阶梯型碳交易机制,并利用电转气(power to gas, P2G)的低碳特性,得到P2G参与碳交易市场的激励机制;其次,由现有DSM的机理与实现方式,在负荷侧考虑不同的DSM来最大化地协调网络的低碳性与经济性;然后,根据所建模型的非凸特性,对气网潮流进行二阶锥松弛且采用连续锥规划算法对松弛间隙进行检验,逐步缩小气潮流的仿真误差,保证松弛的严格性。为了满足不同决策主体的分散自治权与信息私密性,在上述基础上建立分散式优化模型并引入基于嵌套连续锥规划的同步交替方向乘子法(synchronous-alternating direction method of multipliers, S-ADMM)进行求解;最后,通过算例仿真对不同场景下网络的调度结果及不同的调度策略下的运行结果进行比较分析。结果表明,在阶梯型碳交易机制下,虽然总碳交易成本增加了0.02%,但碳排量、运行成本分别减少了4.53%和3.74%;DSM参与到所提模型中使碳排量、弃风量分别降低了9.87%和75.4%,进而有效地提升了电-气互联网络的低碳经济性。 相似文献