全文获取类型
收费全文 | 1983篇 |
免费 | 89篇 |
国内免费 | 67篇 |
专业分类
电工技术 | 37篇 |
综合类 | 184篇 |
化学工业 | 557篇 |
金属工艺 | 89篇 |
机械仪表 | 30篇 |
建筑科学 | 15篇 |
矿业工程 | 6篇 |
能源动力 | 219篇 |
轻工业 | 89篇 |
水利工程 | 8篇 |
石油天然气 | 4篇 |
武器工业 | 2篇 |
无线电 | 156篇 |
一般工业技术 | 248篇 |
冶金工业 | 32篇 |
原子能技术 | 6篇 |
自动化技术 | 457篇 |
出版年
2024年 | 1篇 |
2023年 | 160篇 |
2022年 | 47篇 |
2021年 | 66篇 |
2020年 | 109篇 |
2019年 | 122篇 |
2018年 | 36篇 |
2017年 | 82篇 |
2016年 | 92篇 |
2015年 | 106篇 |
2014年 | 145篇 |
2013年 | 108篇 |
2012年 | 132篇 |
2011年 | 179篇 |
2010年 | 134篇 |
2009年 | 138篇 |
2008年 | 93篇 |
2007年 | 123篇 |
2006年 | 78篇 |
2005年 | 38篇 |
2004年 | 19篇 |
2003年 | 25篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 18篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
排序方式: 共有2139条查询结果,搜索用时 62 毫秒
71.
本文对Linux裁剪进行了基本的阐述和说明,对文件系统的裁剪提出了具体的思路,取消预先分配策略和使用B+树的查找算法来提高文件系统的性能。 相似文献
72.
Zhengmao Liu Xianguo Lu Sun Yonghe Chen Zhike Haitao Wu Yanbo Zhao 《Water Resources Management》2012,26(6):1455-1475
Naoli river basin(NRB), with an area of 24,863 km2, is the largest basin and also the largest marsh distribution area in Sanjiang Plain, Heilongjiang, China. The hydrological
evolution process of wetland in NRB has made a marked ecological responses for anthropic activities, also reflects the drying
trend of the Sanjiang Plain, Northeast China. Global climate warming also contributes to the hydrological evolution process.
The following key research results are obtained: (1) The monthly average water level of Naoli river at Caizuizi hydrological
station in different ages showed a marked decline tendency, the annual mean water level dropped from 96.63 m during 1960–1969
to 95.59 m during 2000–2005, the water level drawdown is 1.04 m; (2) The annual runoff flowing into wetlands in NRB decreased.
Duration of Naoli river and its tributaries being thoroughly frozen from riverbed to river-water-surface showed an prolonged
trend, and the water level drawdown in frozen seasons increased. The water storage capacities of wetlands in NRB declined.
(3) The interactions between ground water and surface water in wetland areas are close. The ground water level variation span
is bigger than that of surface water level in wetland areas of NRB. The drawdown of ground water level promotes the surface
water level to decline, correspondingly. In recent 20 years, the cultivated area extension of rice field in upstream NRB has
made an adverse influence on the hydrological processes of wetlands. (4) The wetland area decrease and farmland area increase
significantly contribute to the runoff depth decrease of wetlands in NRB. The runoff depth variability has been mostly posed
by anthropic activities. (5) Reservoirs, ditches and dykes in NRB have greatly changed the runoff generation processes. Thickness
of the seasonal frozen soil layer becoming thinner and the evaporation potential becoming bigger also contribute to the runoff
depth reduction and the water level drawdown of rivers. The present study results will provide a scientific basic for developing
an integrated watershed management program for NRB, especially, restoring the wetland hydrological processes, maintaining
or improving the wetland structure and enhancing the wetland service functions. 相似文献
73.
This paper made major research on the target representation problem, which plays a significant role in visual tracking, but has received little attention in most researches. In order to fulfill the requirements of tracking robustness and effectiveness in practical conditions, a dynamic appearance model is constructed. Due to particle filter's excellent characteristics, it is employed in this paper not only to estimate target's state, but also to construct the dynamic observation model integrated by multiple cues. In the proposed method, a dynamic multi-cue integration model is constructed for particle filter framework. And a systematic study is done on evaluating cue's weight. Specially, a particle filter based weight tracker is designed to update multi-cue's integrating manner online, so as to adapt the observation model to target's appearance changes. In such a way, a double-particle-filter based tracking framework is formed, and it is field tested on a variety of videos in different tracking conditions. In the experiments and comparisons, the applicable conditions of the proposed dynamic model are discussed, and its robustness and effectiveness are demonstrated. 相似文献
74.
75.
Bioflocculant-producing bacteria Agrobacterium tumefaciens F2 and Bacillus sphaeicus F6 were immobilized onto mycelial pellets to investigate the bioflocculant-producing potential of this combined organism and the corresponding flocculating efficiency. The atomic force microscope (AFM) images of mycelial surface indicate that the mycelia pellet can immobilize bioflocculant-producing bacteria F2 and F6 as a biomass carrier. The flocculating efficiency of bioflocculant produced by this combined organism was studied under the optimum flocculating conditions obtained by Response Surface Methodology (RSM). The fermentation yield of the combined mycelial pellet is about 2.6 g/L, which is higher than that of the free bacteria (only 2.2 g/L). Flocculating efficiency of the combined mycelial pellet was comparable with that of bioflocculant generated by the free bacteria. The bioflocculant yield is enhanced and the flocculating efficiency of the co-culture is uninfluenced after immobilized with mycelial pellet as a carrier. In conclusion, the mycelial pellet is feasible as a biomass carrier for the immobilization of bioflocculant-producing bacteria. 相似文献
76.
针对几种经典算法的效率问题,提出了一种最近点对求解算法:算法预先找到X、Y坐标轴最大、最小坐标值,将点集按某坐标轴排序,并根据鸽巢原理计算最近点对i间距离的上限,由此上限将整个点集分割成不同的区域,最后在每个区域中通过动态缩小每个点的矩形窗减少了算法的计算次数.通过理论证明和实际验证得出:初始点集有序时算法的时间复杂度为O(n);无序时在一般情况下为O(n),最坏情况下为O(nlogn);算法的时间复杂度和运行时间明显优于经典分治算法和基于底函数的算法. 相似文献
77.
WordNet中的综合概念语义相似度计算方法 总被引:1,自引:0,他引:1
作为语义异构问题的基础,概念间语义相似度计算已成为研究热点,对此,提出一种基于WordNet的综合概念语义相似度计算方法. 该方法不仅集成了传统的基于语义距离的算法和基于信息内容的算法,而且引入了深度、密度因子和语义重合度来进行综合分析,并针对综合算法中权值难以确定的问题,引入主成分分析改进权值分配方法. 实验结果表明,改进后的方法计算的相似度与人工判断的相似度相关性较高,有效改善了概念语义相似度计算的准确性. 相似文献
78.
存款保险制度在国际上已经得到了广泛的实行,因其在保护银行业稳定以及安全性等多方面的优势。但因为保险容易间接促成银行从事更高风险的投资行为,反过来又影响了银行的稳定性和金融安全,从而引起了很多争议。任何市场化国家(我国也不例外)都不能回避存款保险制度,所以中国建成何种存款保险制度模式将直接影响到银行行为和金融系统的稳定。面对制度本身所蕴含的道德风险以及逆向选择等问题,需要在制度本身的建设、外界监管以及额度确定等方面做出充分的考虑。 相似文献
79.
近年来的研究表明,自然界中能够为人们所理解的信号都具有稀疏的性质。利用信号的稀疏性,提出了一种基于被擦除信号重要子空间匹配追踪的擦除补偿方法。首先,在给定错误率的基础上定义了信号稀疏性的度量方法。然后,依据被擦除信号的有效部分基于正交匹配追踪方法来寻找信号的重要子空间。最后,基于迭代方程在信号的重要子空间中获得信号的近似表示,并将其作为被擦除信号的补偿信号。模拟实验结果显示了所提出方法补偿被擦除信号的有效性。 相似文献
80.
Jingquan Sha Cheng Wang Jun Peng Aixiang Tian Jing Chen Pengpeng Zhang 《Inorganic chemistry communications》2007,10(12):1469-1472
A novel two-dimensional molybdenum oxide polymer, [Mo4O13]n · 2nH3O, has been prepared under specific hydrothermal conditions and characterized by IR spectroscopy and TG analysis. Single-crystal X-ray diffraction analysis reveals that compound 1 exhibits a (3, 4, 5, 6)-connected 2D layer structure with (32·4)(32·53·8)(3·42·54·6·82)(34·43·54·64) topology, which is constructed by two parallel molybdenum oxide dimeric chains (Mo2O10)n bound together by the dimer of Mo2O9 subunits via the sharing of corners. Additionally, the electrochemistry activity of compound 1 is also reported. 相似文献