全文获取类型
收费全文 | 392386篇 |
免费 | 13387篇 |
国内免费 | 6137篇 |
学科分类
工业技术 | 411910篇 |
出版年
2022年 | 4140篇 |
2021年 | 6812篇 |
2020年 | 5235篇 |
2019年 | 5088篇 |
2018年 | 6847篇 |
2017年 | 7472篇 |
2016年 | 7109篇 |
2015年 | 7092篇 |
2014年 | 9972篇 |
2013年 | 18618篇 |
2012年 | 14417篇 |
2011年 | 17586篇 |
2010年 | 14427篇 |
2009年 | 15306篇 |
2008年 | 15432篇 |
2007年 | 15143篇 |
2006年 | 14080篇 |
2005年 | 12718篇 |
2004年 | 10915篇 |
2003年 | 10208篇 |
2002年 | 9737篇 |
2001年 | 9607篇 |
2000年 | 9383篇 |
1999年 | 9859篇 |
1998年 | 18905篇 |
1997年 | 13804篇 |
1996年 | 10966篇 |
1995年 | 8612篇 |
1994年 | 7440篇 |
1993年 | 7077篇 |
1992年 | 5226篇 |
1991年 | 4832篇 |
1990年 | 4556篇 |
1989年 | 4477篇 |
1988年 | 4091篇 |
1987年 | 3615篇 |
1986年 | 3539篇 |
1985年 | 3826篇 |
1984年 | 3514篇 |
1983年 | 3252篇 |
1982年 | 3083篇 |
1981年 | 3074篇 |
1980年 | 3059篇 |
1979年 | 2839篇 |
1978年 | 2872篇 |
1977年 | 3122篇 |
1976年 | 4079篇 |
1975年 | 2407篇 |
1974年 | 2366篇 |
1973年 | 2377篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Traditionally, in supervised machine learning, (a significant) part of the available data (usually 50%-80%) is used for training and the rest—for validation. In many problems, however, the data are highly imbalanced in regard to different classes or does not have good coverage of the feasible data space which, in turn, creates problems in validation and usage phase. In this paper, we propose a technique for synthesizing feasible and likely data to help balance the classes as well as to boost the performance in terms of confusion matrix as well as overall. The idea, in a nutshell, is to synthesize data samples in close vicinity to the actual data samples specifically for the less represented (minority) classes. This has also implications to the so-called fairness of machine learning. In this paper, we propose a specific method for synthesizing data in a way to balance the classes and boost the performance, especially of the minority classes. It is generic and can be applied to different base algorithms, for example, support vector machines, k-nearest neighbour classifiers deep neural, rule-based classifiers, decision trees, and so forth. The results demonstrated that (a) a significantly more balanced (and fair) classification results can be achieved and (b) that the overall performance as well as the performance per class measured by confusion matrix can be boosted. In addition, this approach can be very valuable for the cases when the number of actual available labelled data is small which itself is one of the problems of the contemporary machine learning. 相似文献
62.
Journal of Communications Technology and Electronics - Abstract—The two-dimensional diffraction problem of a plane polarized TM-wave on two identical solid silver nanocylinders is considered.... 相似文献
63.
Metallurgical and Materials Transactions B - The process of obtaining titanium tetrachloride (TiCl4) from the quartz-leucoxene concentrate (QLC) from the Yaregskoe oil-titanium field was studied.... 相似文献
64.
The existing analytical average bit error rate (ABER) expression of conventional generalised spatial modulation (CGSM) does not agree well with the Monte Carlo simulation results in the low signal‐to‐noise ratio (SNR) region. Hence, the first contribution of this paper is to derive a new and easy way to evaluate analytical ABER expression that improves the validation of the simulation results at low SNRs. Secondly, a novel system termed CGSM with enhanced spectral efficiency (CGSM‐ESE) is presented. This system is realised by applying a rotation angle to one of the two active transmit antennas. As a result, the overall spectral efficiency is increased by 1 bit/s/Hz when compared with the equivalent CGSM system. In order to validate the simulation results of CGSM‐ESE, the third contribution is to derive an analytical ABER expression. Finally, to improve the ABER performance of CGSM‐ESE, three link adaptation algorithms are developed. By assuming full knowledge of the channel at the receiver, the proposed algorithms select a subset of channel gain vector (CGV) pairs based on the Euclidean distance between all CGV pairs, CGV splitting, CGV amplitudes, or a combination of these. 相似文献
65.
66.
67.
Wesley P. Chan Hiroto Mizohana Xiangyu Chen Yasuto Shiigi Yoshiyuki Yamanoue Masaki Nagatsuka Masayuki Inaba 《野外机器人技术杂志》2019,36(1):17-33
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition. 相似文献
68.
69.
70.