全文获取类型
收费全文 | 70290篇 |
免费 | 6843篇 |
国内免费 | 4108篇 |
专业分类
电工技术 | 4167篇 |
技术理论 | 5篇 |
综合类 | 5297篇 |
化学工业 | 11699篇 |
金属工艺 | 4068篇 |
机械仪表 | 4363篇 |
建筑科学 | 4998篇 |
矿业工程 | 1857篇 |
能源动力 | 1666篇 |
轻工业 | 6788篇 |
水利工程 | 1464篇 |
石油天然气 | 3307篇 |
武器工业 | 584篇 |
无线电 | 8146篇 |
一般工业技术 | 8282篇 |
冶金工业 | 2953篇 |
原子能技术 | 796篇 |
自动化技术 | 10801篇 |
出版年
2024年 | 367篇 |
2023年 | 1191篇 |
2022年 | 2128篇 |
2021年 | 2830篇 |
2020年 | 2187篇 |
2019年 | 1905篇 |
2018年 | 2113篇 |
2017年 | 2338篇 |
2016年 | 2141篇 |
2015年 | 2936篇 |
2014年 | 3642篇 |
2013年 | 4464篇 |
2012年 | 5014篇 |
2011年 | 5506篇 |
2010年 | 5040篇 |
2009年 | 4979篇 |
2008年 | 4711篇 |
2007年 | 4464篇 |
2006年 | 4156篇 |
2005年 | 3522篇 |
2004年 | 2495篇 |
2003年 | 2051篇 |
2002年 | 1995篇 |
2001年 | 1659篇 |
2000年 | 1360篇 |
1999年 | 1264篇 |
1998年 | 882篇 |
1997年 | 734篇 |
1996年 | 643篇 |
1995年 | 546篇 |
1994年 | 471篇 |
1993年 | 347篇 |
1992年 | 266篇 |
1991年 | 220篇 |
1990年 | 141篇 |
1989年 | 152篇 |
1988年 | 92篇 |
1987年 | 64篇 |
1986年 | 45篇 |
1985年 | 27篇 |
1984年 | 24篇 |
1983年 | 16篇 |
1982年 | 23篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
This paper addresses the food distribution decision from a wholesaler's perspective, as the wholesalers are often faced with thorny issues such as when, where, how to deliver products at the lowest costs to best satisfy the retailers’ changing needs. This research relies on a distribution problem encountered at Northern Grocery Company in Beijing as an example to develop a two-stage solution procedure and subsequent computer-enabled programs for identifying efficient vehicle routing alternatives. The solution process, which integrates heuristic search algorithms and an integer programming model, can be applied to a wide range of distribution problems with specified route durations and a circular transportation network structure as exemplified by City of Beijing. 相似文献
102.
103.
Jianjun Lei Cuicui Zhang Min Wu Lei You Kefeng Fan Chunping Hou 《Multimedia Tools and Applications》2017,76(6):7661-7676
Large holes are unavoidably generated in depth image based rendering (DIBR) using a single color image and its associated depth map. Such holes are mainly caused by disocclusion, which occurs around the sharp depth discontinuities in the depth map. We propose a divide-and-conquer hole-filling method which refines the background depth pixels around the sharp depth discontinuities to address the disocclusion problem. Firstly, the disocclusion region is detected according to the degree of depth discontinuity, and the target area is marked as a binary mask. Then, the depth pixels located in the target area are modified by a linear interpolation process, whose pixel values decrease from the foreground depth value to the background depth value. Finally, in order to remove the isolated depth pixels, median filtering is adopted to refine the depth map. In these ways, disocclusion regions in the synthesized view are divided into several small holes after DIBR, and are easily filled by image inpainting. Experimental results demonstrate that the proposed method can effectively improve the quality of the synthesized view subjectively and objectively. 相似文献
104.
Hu Changhui Lu Xiaobo Ye Mengjun Zeng Weili Du Yijun 《Multimedia Tools and Applications》2017,76(24):26523-26550
Multimedia Tools and Applications - The extended sparse representation classifier (ESRC) is one of the state-of-the-art solutions for single sample face recognition, but it performs... 相似文献
105.
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
106.
In this work, we aim to discover real-world events from Flickr data by devising a three-stage event detection framework. In the first stage, a multimodal fusion (MF) model is designed to deal with the heterogeneous feature modalities possessed by the user-shared data, which is advantageous in computation complexity. In the second stage, a dual graph regularized non-negative matrix factorization (DGNMF) model is proposed to learn compact feature representations. DGNMF incorporates Laplacian regularization terms for the data graph and base graph into the objective, keeping the geometry structures underlying the data samples and dictionary bases simultaneously. In the third stage, hybrid clustering algorithms are applied seamlessly to discover event clusters. Extensive experiments conducted on the real-world dataset reveal the MF-DGNMF-based approaches outperform the baselines. 相似文献
107.
Universal Access in the Information Society - Helping blind people to build cognitive maps of an environment is one of the aims of several assistive systems. In order to evaluate such assistive... 相似文献
108.
Opportunistic routing is a candidate for multihop wireless routing where the network topology and radio channels vary rapidly. However, there are not many opportunistic routing algorithms that can be implemented in a real multihop wireless network while exploiting the node mobility. It motivates us to implement an opportunistic routing, random basketball routing (BR), in a real multi-robot network to see if it can enhance the capacity of the multihop network as mobility increases. For implementation purposes, we added some features, such as destination RSSI measuring, a loop-free procedure and distributed relay probability updating, to the original BR. We carried out the experiments on a real multi-robot network and compared BR with AODV combined with CSMA/CA (routing + MAC protocol). We considered both static and dynamic scenarios. Our experiments are encouraging in that BR outperforms AODV + CSMA/CA, particularly in dynamic cases; the throughput of BR is 6.6 times higher than that of AODV + CSMA/CA. BR with dynamic networks shows 1.4 times higher throughput performance than BR with static networks. We investigate the performance of BR in the large-scale network using NS-2 simulation. We verify the effect of node density, speed, destination beacon signal and loop-free procedure. According to the large-scale simulation, the end-to-end throughput grows with the node speed. 相似文献
109.
We propose a new approximate numerical algorithm for the steady-state solution of general structured ergodic Markov models. The approximation uses a state-space encoding based on multiway decision diagrams and a transition rate encoding based on a new class of edge-valued decision diagrams. The new method retains the favorable properties of a previously proposed Kronecker-based approximation, while eliminating the need for a Kronecker-consistent model decomposition. Removing this restriction allows for a greater utilization of event locality, which facilitates the generation of both the state-space and the transition rate matrix, thus extends the applicability of this algorithm to larger and more complex models. 相似文献
110.
基于Linux的实时音频与视频传输 总被引:1,自引:0,他引:1
讨论了多媒体会议中音频与视频的传输特性、要求和协议标准。并给出了程序实现。 相似文献