全文获取类型
收费全文 | 2572篇 |
免费 | 279篇 |
国内免费 | 230篇 |
专业分类
电工技术 | 125篇 |
综合类 | 128篇 |
化学工业 | 152篇 |
金属工艺 | 77篇 |
机械仪表 | 86篇 |
建筑科学 | 54篇 |
矿业工程 | 21篇 |
能源动力 | 32篇 |
轻工业 | 77篇 |
水利工程 | 26篇 |
石油天然气 | 20篇 |
武器工业 | 63篇 |
无线电 | 470篇 |
一般工业技术 | 244篇 |
冶金工业 | 124篇 |
原子能技术 | 43篇 |
自动化技术 | 1339篇 |
出版年
2024年 | 4篇 |
2023年 | 37篇 |
2022年 | 64篇 |
2021年 | 40篇 |
2020年 | 53篇 |
2019年 | 83篇 |
2018年 | 74篇 |
2017年 | 86篇 |
2016年 | 93篇 |
2015年 | 116篇 |
2014年 | 165篇 |
2013年 | 182篇 |
2012年 | 186篇 |
2011年 | 195篇 |
2010年 | 137篇 |
2009年 | 157篇 |
2008年 | 191篇 |
2007年 | 163篇 |
2006年 | 166篇 |
2005年 | 132篇 |
2004年 | 89篇 |
2003年 | 99篇 |
2002年 | 76篇 |
2001年 | 62篇 |
2000年 | 78篇 |
1999年 | 45篇 |
1998年 | 57篇 |
1997年 | 48篇 |
1996年 | 42篇 |
1995年 | 20篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 16篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1966年 | 1篇 |
1955年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有3081条查询结果,搜索用时 156 毫秒
41.
42.
In this paper,a TPP(Task-based Parallelization and Pipelining)scheme is proposed to implement AVS(Audio Video coding Standard)video decoding algorithm on REMUS(REconfigurable MUltimedia System),which is a coarse-grained reconfigurable multimedia system.An AVS decoder has been implemented with the consideration of HW/SW optimized partitioning.Several parallel techniques,such as MB(Macro-Block)-based parallel and block-based parallel techniques,and several pipeline techniques,such as MB level pipeline and block level pipeline techniques are adopted by hardware implementation,for performance improvement of the AVS decoder.Also,most computation-intensive tasks in AVS video standards,such as MC(Motion Compensation),IP(Intra Prediction),IDCT(Inverse Discrete Cosine Transform),REC(REConstruct)and DF(Deblocking Filter),are performed in the two RPUs(Reconfigurable Processing Units),which are the major computing engines of REMUS.Owing to the proposed scheme,the decoder introduced here can support AVS JP(Jizhun Profile)1920×1088@39fps streams when exploiting a 200 MHz working frequency. 相似文献
43.
目的 视觉检索需要准确、高效地从大型图像或者视频数据集中检索出最相关的视觉内容,但是由于数据集中图像数据量大、特征维度高的特点,现有方法很难同时保证快速的检索速度和较好的检索效果。方法 对于面向图像视频数据的高维数据视觉检索任务,提出加权语义局部敏感哈希算法(weighted semantic locality-sensitive hashing, WSLSH)。该算法利用两层视觉词典对参考特征空间进行二次空间划分,在每个子空间里使用加权语义局部敏感哈希对特征进行精确索引。其次,设计动态变长哈希码,在保证检索性能的基础上减少哈希表数量。此外,针对局部敏感哈希(locality sensitive hashing, LSH)的随机不稳定性,在LSH函数中加入反映参考特征空间语义的统计性数据,设计了一个简单投影语义哈希函数以确保算法检索性能的稳定性。结果 在Holidays、Oxford5k和DataSetB数据集上的实验表明,WSLSH在DataSetB上取得最短平均检索时间0.034 25 s;在编码长度为64位的情况下,WSLSH算法在3个数据集上的平均精确度均值(mean average precision,mAP)分别提高了1.2%32.6%、1.7%19.1%和2.6%28.6%,与几种较新的无监督哈希方法相比有一定的优势。结论 通过进行二次空间划分、对参考特征的哈希索引次数进行加权、动态使用变长哈希码以及提出简单投影语义哈希函数来对LSH算法进行改进。由此提出的加权语义局部敏感哈希(WSLSH)算法相比现有工作有更快的检索速度,同时,在长编码的情况下,取得了更为优异的性能。 相似文献
44.
45.
齐齐哈尔工业区春季大气中PBDEs的污染及气粒分配 总被引:1,自引:0,他引:1
齐齐哈尔富拉尔基区为典型的国家重工业集中区域,为研究其大气中多溴联苯醚(PBDEs)的质量浓度水平、污染特征和气/粒分配规律,分别在其下风向和上风向采集大气颗粒相和气相样品,对PBDEs的质量浓度进行测定.结果表明,大气中PBDEs总质量浓度为13.9~102 pg·m-3,平均值为53.6 pg·m-3,BDE-209是质量浓度最高的同系物.来源分析表明,PBDEs主要来源于商用五溴联苯醚和十溴联苯醚的使用.由log KP和log poL线性回归得到的斜率均高于平衡状态理论值-1,说明大气中的PBDEs气粒分配未达到平衡状态.采用Junge-Pankow吸附模型和Harner-Bidleman吸收模型对PBDEs颗粒态百分比(φ)进行了模拟,结果均高于实际值. 相似文献
46.
The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation achieved. Meanwhile, it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation, as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles burst. This causes the increased concentration in the froth compared to the bulk concentration, named as frother partitioning. Partitioning reflects the adsorption of frother on bubbles and how to influence bubble size is not known. There currently exists no such a topic aiming to link these two key parameters. To fill this vacancy, the correspondence between bubble size and frother partitioning was examined. Bubble size was measured by sampling-for-imaging (SFI) technique. Using total organic carbon (TOC) analysis to measure the frother partitioning between froth and bulk phases was determined. Measurements have shown, with no exceptions including four different frothers, higher frother concentration is in the bulk than in the froth. The results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two, represented byCFroth/CBulk andD32. TheCFroth/CBulk andD32 curves show similar exponential decay relationships as a function of added frother in the system, strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction. 相似文献
47.
The challenges of machining, particularly milling, glass fibre-reinforced polymer (GFRP) composites are their abrasiveness (which lead to excessive tool wear) and susceptible to workpiece damage when improper machining parameters are used. It is imperative that the condition of cutting tool being monitored during the machining process of GFRP composites so as to re-compensating the effect of tool wear on the machined components. Until recently, empirical data on tool wear monitoring of this material during end milling process is still limited in existing literature. Thus, this paper presents the development and evaluation of tool condition monitoring technique using measured machining force data and Adaptive Network-Based Fuzzy Inference Systems during end milling of the GFRP composites. The proposed modelling approaches employ two different data partitioning techniques in improving the predictability of machinability response. Results show that superior predictability of tool wear was observed when using feed force data for both data partitioning techniques. In particular, the ANFIS models were able to match the nonlinear relationship of tool wear and feed force highly effective compared to that of the simple power law of regression trend. This was confirmed through two statistical indices, namely r2 and root mean square error (RMSE), performed on training as well as checking datasets. 相似文献
48.
LTE-A是一种4G移动通信标准,可满足移动数据业务对传输带宽的要求。为解决移动通信网络中室内信号质量较差的问题,LTE-A标准采用飞蜂窝技术作为室内无线接入解决方案。针对LTE-A飞蜂窝网络的时延边界问题,运用随机网络演算方法分析业务流的自相似性质和MIMO信道的时变特性,构建了LTE-A飞蜂窝网络中自相似业务流的随机到达与随机服务模型。围绕所构建的到达与服务模型,运用有效带宽理论和chernoff界方法,给出了自相似业务流的端到端时延边界。NS3仿真验证表明,在信道带宽和业务流优先级等指标不同的情形下,所给出的理论端到端时延边界与仿真时延的偏差在2ms以内,较为准确有效,可为确保LTE-A飞蜂窝网络的服务质量提供依据。 相似文献
49.
50.
A new algorithm, dubbed memory-based adaptive partitioning (MAP) of search space, which is intended to provide a better accuracy/speed ratio in the convergence of multi-objective evolutionary algorithms (MOEAs) is presented in this work. This algorithm works by performing an adaptive-probabilistic refinement of the search space, with no aggregation in objective space. This work investigated the integration of MAP within the state-of-the-art fast and elitist non-dominated sorting genetic algorithm (NSGAII). Considerable improvements in convergence were achieved, in terms of both speed and accuracy. Results are provided for several commonly used constrained and unconstrained benchmark problems, and comparisons are made with standalone NSGAII and hybrid NSGAII-efficient local search (eLS). 相似文献