全文获取类型
收费全文 | 604952篇 |
免费 | 94464篇 |
国内免费 | 58262篇 |
专业分类
电工技术 | 50274篇 |
技术理论 | 65篇 |
综合类 | 45464篇 |
化学工业 | 93604篇 |
金属工艺 | 44919篇 |
机械仪表 | 33612篇 |
建筑科学 | 45719篇 |
矿业工程 | 26003篇 |
能源动力 | 20319篇 |
轻工业 | 45439篇 |
水利工程 | 14329篇 |
石油天然气 | 37567篇 |
武器工业 | 6924篇 |
无线电 | 76376篇 |
一般工业技术 | 78773篇 |
冶金工业 | 29596篇 |
原子能技术 | 5572篇 |
自动化技术 | 103123篇 |
出版年
2024年 | 4070篇 |
2023年 | 10334篇 |
2022年 | 15871篇 |
2021年 | 20981篇 |
2020年 | 20316篇 |
2019年 | 26952篇 |
2018年 | 29900篇 |
2017年 | 32281篇 |
2016年 | 30810篇 |
2015年 | 34088篇 |
2014年 | 37498篇 |
2013年 | 41201篇 |
2012年 | 41788篇 |
2011年 | 41387篇 |
2010年 | 36261篇 |
2009年 | 32292篇 |
2008年 | 30222篇 |
2007年 | 28579篇 |
2006年 | 28781篇 |
2005年 | 25679篇 |
2004年 | 20811篇 |
2003年 | 17811篇 |
2002年 | 16233篇 |
2001年 | 14875篇 |
2000年 | 14928篇 |
1999年 | 16242篇 |
1998年 | 14019篇 |
1997年 | 11963篇 |
1996年 | 11276篇 |
1995年 | 9905篇 |
1994年 | 8181篇 |
1993年 | 6488篇 |
1992年 | 5607篇 |
1991年 | 4248篇 |
1990年 | 3366篇 |
1989年 | 2937篇 |
1988年 | 2347篇 |
1987年 | 1213篇 |
1986年 | 931篇 |
1985年 | 669篇 |
1984年 | 454篇 |
1983年 | 357篇 |
1982年 | 394篇 |
1981年 | 304篇 |
1980年 | 258篇 |
1978年 | 155篇 |
1976年 | 323篇 |
1975年 | 233篇 |
1972年 | 252篇 |
1960年 | 207篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
丙烯腈装置回收塔内聚合物生成原因的分析 总被引:2,自引:0,他引:2
针对丙烯腈生产过程中回收塔内聚合物堵塞降液管造成回收塔运行周期短的问题,通过对丙烯腈回收塔内各组分分布的模拟计算,直观显示了回收塔内各组分的浓度分布,发现了回收塔的聚合段与丙烯醛的富集段相吻合的现象,初步得出了回收塔内局部聚合的原因;通过对塔内聚合物的特性分析和评判,进一步证实了“回收塔内局部聚合严重是由于在聚合段丙烯醛聚集引起”这一现象;根据模拟计算结果和实际运行经验,提出了预防聚合物堵塞降液管的措施,并进行了部分生产验证,为丙烯腈生产企业延长装置运行周期提供了理论指导。 相似文献
32.
Analysis and architecture design of variable block-size motion estimation for H.264/AVC 总被引:1,自引:0,他引:1
Ching-Yeh Chen Shao-Yi Chien Yu-Wen Huang Tung-Chien Chen Tu-Chih Wang Liang-Gee Chen 《IEEE transactions on circuits and systems. I, Regular papers》2006,53(3):578-593
Variable block-size motion estimation (VBSME) has become an important video coding technique, but it increases the difficulty of hardware design. In this paper, we use inter-/intra-level classification and various data flows to analyze the impact of supporting VBSME in different hardware architectures. Furthermore, we propose two hardware architectures that can support traditional fixed block-size motion estimation as well as VBSME with less chip area overhead compared to previous approaches. By broadcasting reference pixel rows and propagating partial sums of absolute differences (SADs), the first design has the fewer reference pixel registers and a shorter critical path. The second design utilizes a two-dimensional distortion array and one adder tree with the reference buffer that can maximize the data reuse between successive searching candidates. The first design is suitable for low resolution or a small search range, and the second design has advantages of supporting a high degree of parallelism and VBSME. Finally, we propose an eight-parallel SAD tree with a shared reference buffer for H.264/AVC integer motion estimation (IME). Its processing ability is eight times of the single SAD tree, but the reference buffer size is only doubled. Moreover, the most critical issue of H.264 IME, which is huge memory bandwidth, is overcome. We are able to save 99.9% off-chip memory bandwidth and 99.22% on-chip memory bandwidth. We demonstrate a 720-p, 30-fps solution at 108 MHz with 330.2k gate count and 208k bits on-chip memory. 相似文献
33.
Wu-An Kuo TingTing Hwang Wu A.C.-H. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2006,14(1):81-85
This paper presents a novel power-driven multiplication instruction-set design method for application-specific instruction-set processors (ASIPs). Based on a dual-and-configurable-multiplier structure, our proposed method devises a multiplication instruction set for low-power ASIPs. Our method exploits the execution sequences of multiplication instructions and effective bit widths of variables to reduce power consumed by redundant multiplication bits while minimizing the multiplication execution time. Experimental results on a set of DSP programs demonstrate that our proposed method achieves significant power reduction (up to 18.53%) and execution time improvement (up to 10.43%) with 18% area overhead. 相似文献
34.
35.
根据Flether等人的研究,基于感知独立性假设的子带识别方法被用于抗噪声鲁棒语音识别。本文拓展子带方法,采用基于噪声污染假定的多带框架来减少噪声影响。论文不仅从理论上分析了噪声污染假定多带框架在识别性能上的潜在优势,而且提出了多带环境下的鲁棒语音识别算法。研究表明:多带框架不仅回避了独立感知假设要求,而且与子带方法相比,多带方法能更好的减少噪声影响,提高系统识别性能。 相似文献
36.
A new detection algorithm (NDA) based on fuzzy cellular neural networks for white blood cell detection. 总被引:1,自引:0,他引:1
White blood cell detection is one of the most basic and key steps in the automatic recognition system of white blood cells in microscopic blood images. Its accuracy and stability greatly affect the operating speed and recognition accuracy of the whole system. But there are only a few methods available for cell detection or segmentation due to the complexity of the microscopic images. This paper focuses on this issue. Based on the detailed analysis of the existing two methods--threshold segmentation followed by mathematical morphology (TSMM), and the fuzzy logic method--a new detection algorithm (NDA) based on fuzzy cellular neural networks is proposed. NDA combines the advantages of TSMM and the fuzzy logic method, and overcomes their drawbacks. With NDA, we can detect almost all white blood cells, and the contour of each detected cell is nearly complete. Its adaptability is strong and the running speed is expected to be comparatively high due to the easy hardware implementation of FCN. Experimental results show good performance. 相似文献
37.
以2个小水电站径流计算为实例,分析移用降雨径流关系和参证站选择的教训,对改进小水电站径流计算方法提出了建议。表4个。 相似文献
38.
A locomotive cabin adsorption air‐conditioner has been equipped in #DF4B‐2369 locomotive; and has been successfully run for 2 years. It is powered by waste heat from the exhaust of the diesel engine. The influence on heat transfer is described by the equivalent heat transfer coefficient or thermal resistance of components inside the adsorber. The variation of adsorption capacity is expressed by a non‐equilibrium adsorption function. The dynamic heat transfer process of adsorption air‐conditioning system is treated with the lumped parameter method. Some typical running experimental results are present. The diesel engine rotating speed and locomotive speed influenced on the refrigeration system are discussed. The maximum mean refrigeration power is regarded as an objective function. Based on experiments and theoretical analysis, the running characteristics of the air‐conditioning system are optimized. Some techniques of performance improvement are suggested as well. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
39.
21世纪是信息的时代,信息时代又被称为数字化时代,在新形势、新任务下,房产管理部门和房产档案部门传统的以手工处理为主的管理方式将不能适应新形势和信息时代发展的需要。笔者认为,在新形势下,解放思想,加快房地产信息化建设步伐,积极实施房地产权属档案微机数字化管理是当前构建和谐房地产行政管理的重要举措和任务。 相似文献
40.
在对企业虚拟人力资源管理内涵及特征进行阐述的基础上,分析了虚拟人力资源在信息技术、时间和空间上的柔性特征,会对员工工作模式、员工职业生涯等方面产生影响,从而产生了诸如员工利益、企业安全、多头领导、有效沟通等问题,并提出了建议和对策。 相似文献