全文获取类型
收费全文 | 3201篇 |
免费 | 351篇 |
国内免费 | 158篇 |
专业分类
电工技术 | 226篇 |
综合类 | 198篇 |
化学工业 | 677篇 |
金属工艺 | 189篇 |
机械仪表 | 199篇 |
建筑科学 | 244篇 |
矿业工程 | 107篇 |
能源动力 | 82篇 |
轻工业 | 254篇 |
水利工程 | 50篇 |
石油天然气 | 265篇 |
武器工业 | 16篇 |
无线电 | 297篇 |
一般工业技术 | 382篇 |
冶金工业 | 145篇 |
原子能技术 | 63篇 |
自动化技术 | 316篇 |
出版年
2024年 | 25篇 |
2023年 | 66篇 |
2022年 | 131篇 |
2021年 | 170篇 |
2020年 | 142篇 |
2019年 | 102篇 |
2018年 | 92篇 |
2017年 | 132篇 |
2016年 | 91篇 |
2015年 | 152篇 |
2014年 | 161篇 |
2013年 | 184篇 |
2012年 | 182篇 |
2011年 | 191篇 |
2010年 | 164篇 |
2009年 | 123篇 |
2008年 | 169篇 |
2007年 | 194篇 |
2006年 | 178篇 |
2005年 | 158篇 |
2004年 | 102篇 |
2003年 | 74篇 |
2002年 | 84篇 |
2001年 | 76篇 |
2000年 | 79篇 |
1999年 | 91篇 |
1998年 | 49篇 |
1997年 | 72篇 |
1996年 | 58篇 |
1995年 | 54篇 |
1994年 | 38篇 |
1993年 | 33篇 |
1992年 | 19篇 |
1991年 | 20篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有3710条查询结果,搜索用时 15 毫秒
21.
针对某双列直插式(DIP)封装器件在整机温循试验中出现的失效现象,分析在器件与电路板焊接环节、电路板与整机装配环节和整机温循试验环节3个工况下可能的失效原因,对原因分别进行单工况和多工况的失效仿真分析。针对不同仿真模型在不同工况下的叠加仿真难题,提出基于ANSYS Workbench有限元软件的多应力叠加仿真方法,对比单一工况和多种工况下的仿真结果。结果表明,DIP封装器件失效是器件在焊接尺寸不匹配、过定位装配和温循试验三种工况下,机械应力和热应力的叠加使玻璃绝缘子产生裂纹导致的,有限元仿真结果与实验结果基本吻合,为DIP封装器件在多工况下应力叠加失效的故障机理研究提供一种可参考的仿真方法。 相似文献
22.
23.
Consumers are susceptible to reference price effects when they make purchase decisions for a certain product. Meanwhile, the sales price and advertisement are the determinable factors that have impact on consumers’ reference price which are also fundamental marketing strategies. Therefore, how to determine an appropriate sales price and advertising effort level to maximise firms’ profits is an essential task. A joint pricing and advertising problem for a monopolistic firm with consideration of reference price effect is investigated, where consumer demand rate is price-sensitivity and depends on the gap between the sales price and the reference price in consumers’ mind. An optimisation model is established to maximise the firm’s total profit by making a joint pricing and advertising strategy. The static and dynamic joint strategies are obtained by applying Pontryagin’s maximum principle. Results show that the dynamic strategies dominate the static ones. Furthermore, the dynamic pricing and dynamic advertising strategies are strategic complements. Additionally, the length of the sales period plays a key role in determining the superiority of the two dynamic strategies. Specifically, a relatively short sales period highlights the value of the dynamic advertising while a long sales period strengthens the function of the dynamic pricing. 相似文献
24.
25.
TreeNetViz: revealing patterns of networks over tree structures 总被引:1,自引:0,他引:1
Network data often contain important attributes from various dimensions such as social affiliations and areas of expertise in a social network. If such attributes exhibit a tree structure, visualizing a compound graph consisting of tree and network structures becomes complicated. How to visually reveal patterns of a network over a tree has not been fully studied. In this paper, we propose a compound graph model, TreeNet, to support visualization and analysis of a network at multiple levels of aggregation over a tree. We also present a visualization design, TreeNetViz, to offer the multiscale and cross-scale exploration and interaction of a TreeNet graph. TreeNetViz uses a Radial, Space-Filling (RSF) visualization to represent the tree structure, a circle layout with novel optimization to show aggregated networks derived from TreeNet, and an edge bundling technique to reduce visual complexity. Our circular layout algorithm reduces both total edge-crossings and edge length and also considers hierarchical structure constraints and edge weight in a TreeNet graph. These experiments illustrate that the algorithm can reduce visual cluttering in TreeNet graphs. Our case study also shows that TreeNetViz has the potential to support the analysis of a compound graph by revealing multiscale and cross-scale network patterns. 相似文献
26.
Multimedia Tools and Applications - Sparse representation based classification (SRC) and collaborative representation based classification (CRC) are two well-known methods in representation-based... 相似文献
27.
An automatic, adaptive, spectrogram-based algorithm for picking the arrival time of microseismic data is proposed. The algorithm provides a significant improvement in the ratio of detected events to false triggers and in the resolution of the microseismic structure. It mainly addresses the problem of automatic picking when the signal-to-noise ratio (S/N) is low and so false and missed triggers frequently occur. It combines the short time average/long time average (STA/LTA) algorithm with an envelope algorithm. It also constructs an envelope from a time-frequency representation of the signal. The threshold is set dynamically, according to the existing noise level and the S/N ratio. The algorithm also uses the fixed LTA value to represent the noise level for a seismic record. It is applied to pick the arrival times of P-waves of local events recorded at eight stations. 相似文献
28.
基于IMAN的产品数据管理的实现 总被引:4,自引:0,他引:4
该文首先提出了上海家化包装部对 PDM的应用需求,在此基础上讨论了包装部 PDM系统的功能要求、体系结构、硬件配置和开发技术。最后,根据PDM实施的具体实践,分析了 PDM实施的效益和障碍。 相似文献
29.
30.
Xin Luo Huijun Liu Gaopeng Gou Yunni Xia Qingsheng Zhu 《Engineering Applications of Artificial Intelligence》2012,25(7):1403-1412
Collaborative Filtering (CF) can be achieved by Matrix Factorization (MF) with high prediction accuracy and scalability. Most of the current MF based recommenders, however, are serial, which prevent them sharing the efficiency brought by the rapid progress in parallel programming techniques. Aiming at parallelizing the CF recommender based on Regularized Matrix Factorization (RMF), we first carry out the theoretical analysis on the parameter updating process of RMF, whereby we can figure out that the main obstacle preventing the model from parallelism is the inter-dependence between item and user features. To remove the inter-dependence among parameters, we apply the Alternating Stochastic Gradient Solver (ASGD) solver to deal with the parameter training process. On this basis, we subsequently propose the parallel RMF (P-RMF) model, of which the training process can be parallelized through simultaneously training different user/item features. Experiments on two large, real datasets illustrate that our P-RMF model can provide a faster solution to CF problem when compared to the original RMF and another parallel MF based recommender. 相似文献