全文获取类型
收费全文 | 21448篇 |
免费 | 3040篇 |
国内免费 | 1976篇 |
专业分类
电工技术 | 2354篇 |
综合类 | 2554篇 |
化学工业 | 1290篇 |
金属工艺 | 227篇 |
机械仪表 | 1071篇 |
建筑科学 | 703篇 |
矿业工程 | 372篇 |
能源动力 | 422篇 |
轻工业 | 292篇 |
水利工程 | 361篇 |
石油天然气 | 364篇 |
武器工业 | 447篇 |
无线电 | 5771篇 |
一般工业技术 | 1589篇 |
冶金工业 | 348篇 |
原子能技术 | 118篇 |
自动化技术 | 8181篇 |
出版年
2024年 | 161篇 |
2023年 | 375篇 |
2022年 | 575篇 |
2021年 | 668篇 |
2020年 | 728篇 |
2019年 | 717篇 |
2018年 | 664篇 |
2017年 | 919篇 |
2016年 | 953篇 |
2015年 | 975篇 |
2014年 | 1372篇 |
2013年 | 1585篇 |
2012年 | 1507篇 |
2011年 | 1734篇 |
2010年 | 1286篇 |
2009年 | 1302篇 |
2008年 | 1385篇 |
2007年 | 1583篇 |
2006年 | 1222篇 |
2005年 | 1098篇 |
2004年 | 836篇 |
2003年 | 746篇 |
2002年 | 636篇 |
2001年 | 517篇 |
2000年 | 406篇 |
1999年 | 379篇 |
1998年 | 306篇 |
1997年 | 290篇 |
1996年 | 236篇 |
1995年 | 226篇 |
1994年 | 184篇 |
1993年 | 129篇 |
1992年 | 140篇 |
1991年 | 96篇 |
1990年 | 93篇 |
1989年 | 61篇 |
1988年 | 50篇 |
1987年 | 36篇 |
1986年 | 24篇 |
1985年 | 33篇 |
1984年 | 49篇 |
1983年 | 21篇 |
1982年 | 38篇 |
1981年 | 36篇 |
1980年 | 23篇 |
1979年 | 15篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1957年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
对高层建筑设计而言,设计前期的初步结构方案需通过结构软件的计算分析,判断该方案是否正确与合理,从而对其进行有针对性的修改和优化。文章结合具体实例,介绍了分析判断计算结果的主要几项内容及可采取的相应优化措施,从而可以提高设计的准确性和工作效率。 相似文献
72.
论述了重构轮式工程机械轮边减速器优化设计数学模型的必要性,给出了精确化的目标函数,全面化和准确化的设计变量、基于并行设计的约束条件;介绍了对优化解适用性评价的方法和手段。巧妙地解决了优化解中离散变量的圆整问题,提供了基于MATLAB的求解反渐开线函数的M文件。 相似文献
73.
In their comments on the authors' article (see record 2003-10163-009), R. C. Serlin, B. E. Wampold, and J. R. Levin (see record 2003-10163-011) and P. Crits-Christoph, X. Tu, and R. Gallop (see record 2003-10163-010) took issue with the authors' suggestion to evaluate therapy studies with nested providers with a fixed model approach. In this rejoinder, the authors' comment on Serlin et al's critique by showing that their arguments do not apply, are based on misconceptions about the purpose and nature of statistical inference, or are based on flawed reasoning. The authors also comment on Crits-Christoph et al's critique by showing that the proposed approach is very similar to, but less inclusive than, their own suggestion. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
Motion picture films are susceptible to local degradations such as dust spots. Other deteriorations are global such as intensity
and spatial jitter. It is obvious that motion needs to be compensated for before the detection/correction of such local and
dynamic defects. Therefore, we propose a hierarchical motion estimation method ideally suited for high resolution film sequences.
This recursive block-based motion estimator relies on an adaptive search strategy and Radon projections to improve processing
speed. The localization of dust particles then becomes straightforward. Thus, it is achieved by simple inter-frame differences
between the current image and motion compensated successive and preceding frames. However, the detection of spatial and intensity
jitter requires a specific process taking advantage of the high temporal correlation in the image sequence. In this paper,
we present our motion compensation-based algorithms for removing dust spots, spatial and intensity jitter in degraded motion
pictures. Experimental results are presented showing the usefulness of our motion estimator for film restoration at reasonable
computational costs.
Received: 9 July 2000 / Accepted: 13 January 2002
Correspondence to:S. Boukir 相似文献
75.
A generalisation of the Burg algorithm to vector spaces is described. This can be used to subsample time series that have narrow frequency bandwidth, thereby reducing the computation time and the complexity of the autoregressive model required. The technique is preferable to conventional subsampling. 相似文献
76.
基于Legendre多项式的随机连续系统的Markov参数估计 总被引:3,自引:3,他引:0
本文在讨论连续Wisenr过程的Legendre多项式逼近值的相关性和Wiener过程扰动下连续线性系统基于该正交多项的最小二乘估计有偏性后,提出了无偏一致的且数估计误差方差最小的Markov估计(最小方差估计)算法,并给出本文方法的仿真结果。 相似文献
77.
78.
Yan Shuicheng Wang Huan Liu Jianzhuang Tang Xiaoou Thomas S. Huang 《Frontiers of Computer Science in China》2007,1(4):407-412
The techniques for image analysis and classification generally consider the image sample labels fixed and without uncertainties.
The rank regression problem studied in this paper is based on the training samples with uncertain labels, which often is the
case for the manual estimated image labels. A core ranking model is designed first as the bilinear fusing of multiple candidate
kernels. Then, the parameters for feature selection and kernel selection are learned simultaneously by maximum a posteriori
for given samples and uncertain labels. The provable convergency Expectation Maximization (EM) method is used for inferring
these parameters in an iterative manner. The effectiveness of the proposed algorithm is finally validated by the extensive
experiments on age ranking task and human tracking task. The popular FG-NET and the large scale Yamaha aging database are
used for the age estimation experiments, and our algorithm outperforms those state-of-the-art algorithms ever reported by
other interrelated literatures significantly. The experiment result of human tracking task also validates its advantage over
conventional linear regression algorithm.
A short version of this paper appeared in ICME07. 相似文献
79.
80.
Abstract. Large sample properties of the least‐squares and weighted least‐squares estimates of the autoregressive parameter of the explosive random‐coefficient AR(1) process are discussed. It is shown that, contrary to the standard AR(1) case, the least‐squares estimator is inconsistent whereas the weighted least‐squares estimator is consistent and asymptotically normal even when the error process is not necessarily Gaussian. Conditional asymptotics on the event that a certain limiting random variable is non‐zero is also discussed. 相似文献