全文获取类型
收费全文 | 1381篇 |
免费 | 181篇 |
国内免费 | 124篇 |
学科分类
数理化 | 1686篇 |
出版年
2024年 | 4篇 |
2023年 | 22篇 |
2022年 | 54篇 |
2021年 | 97篇 |
2020年 | 81篇 |
2019年 | 56篇 |
2018年 | 48篇 |
2017年 | 45篇 |
2016年 | 66篇 |
2015年 | 62篇 |
2014年 | 66篇 |
2013年 | 100篇 |
2012年 | 62篇 |
2011年 | 63篇 |
2010年 | 51篇 |
2009年 | 86篇 |
2008年 | 78篇 |
2007年 | 64篇 |
2006年 | 68篇 |
2005年 | 67篇 |
2004年 | 50篇 |
2003年 | 50篇 |
2002年 | 50篇 |
2001年 | 36篇 |
2000年 | 30篇 |
1999年 | 34篇 |
1998年 | 20篇 |
1997年 | 24篇 |
1996年 | 31篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 2篇 |
1989年 | 8篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 1篇 |
1984年 | 12篇 |
1979年 | 1篇 |
1959年 | 1篇 |
1957年 | 4篇 |
排序方式: 共有1686条查询结果,搜索用时 15 毫秒
101.
102.
103.
GA-BP嵌套算法的理论及应用 总被引:2,自引:0,他引:2
分析了BP算法、遗传算法以及GA-BP-APARTING算法的特点,提出了GA-BP-NESTING算法.在人工神经网络的在线学习和离线学习方式下,分别对BP算法、GA算法、GA-BP-APARTING算法和GA-BP-NESTING算法进行了比较研究,研究发现:第一,网络初始权值的赋值对人工神经网络训练影响很大;第二,离线学习方式下GA-BP-NESTING算法效果最佳. 相似文献
104.
105.
Artificial intelligence is one of the fastest-developing areas of science that covers a remarkably wide range of problems to be solved. It has found practical application in many areas of human activity, also in medicine. One of the directions of cooperation between computer science and medicine is to assist in diagnosing and proposing treatment methods with the use of IT tools. This study is the result of collaboration with the Children’s Memorial Health Institute in Warsaw, from where a database containing information about patients suffering from Bruton’s disease was made available. This is a rare disorder, difficult to detect in the first months of life. It is estimated that one in 70,000 to 90,000 children will develop Bruton’s disease. But even these few cases need detailed attention from doctors. Based on the data contained in the database, data mining was performed. During this process, knowledge was discovered that was presented in a way that is understandable to the user, in the form of decision trees. The best models obtained were used for the implementation of expert systems. Based on the data introduced by the user, the system conducts expertise and determines the severity of the course of the disease or the severity of the mutation. The CLIPS language was used for developing the expert system. Then, using this language, software was developed producing six expert systems. In the next step, experimental verification was performed, which confirmed the correctness of the developed systems. 相似文献
106.
扫描隧道显微镜原子操纵技术是指利用扫描探针在特定材料表面以晶格为步长搬运单个原子或分子的技术.它是纳米尺度量子物理与器件研究领域一种独特而有力的研究手段.利用这种手段,人们能够以原子或分子为单元构筑某些常规生长或微加工方法难以制备的人工量子结构,通过对格点原子、晶格尺寸、对称性、周期性的高度控制,实现对局域电子态、自旋序、以及能带拓扑特性等量子效应的设计与调控.原子操纵技术与超快测量及自动控制技术的结合,使得人们能够进一步研究原子级精准的量子器件,因而该技术成为探索未来器件新机理、新工艺的重要工具.本文首先简介原子操纵方法的发展过程和技术要点,然后分别介绍人工电子晶格、半导体表面人工量子点、磁性人工量子结构、人工结构中的信息存储与逻辑运算、单原子精度原型器件等方面的最新研究进展,以及单原子刻蚀和自动原子操纵等方面的技术进展,最后总结并展望原子操纵技术的应用前景和发展趋势. 相似文献
107.
Yury Rodimkov Evgeny Efimenko Valentin Volokitin Elena Panova Alexey Polovinkin Iosif Meyerov Arkady Gonoskov 《Entropy (Basel, Switzerland)》2021,23(1)
When entering the phase of big data processing and statistical inferences in experimental physics, the efficient use of machine learning methods may require optimal data preprocessing methods and, in particular, optimal balance between details and noise. In experimental studies of strong-field quantum electrodynamics with intense lasers, this balance concerns data binning for the observed distributions of particles and photons. Here we analyze the aspect of binning with respect to different machine learning methods (Support Vector Machine (SVM), Gradient Boosting Trees (GBT), Fully-Connected Neural Network (FCNN), Convolutional Neural Network (CNN)) using numerical simulations that mimic expected properties of upcoming experiments. We see that binning can crucially affect the performance of SVM and GBT, and, to a less extent, FCNN and CNN. This can be interpreted as the latter methods being able to effectively learn the optimal binning, discarding unnecessary information. Nevertheless, given limited training sets, the results indicate that the efficiency can be increased by optimizing the binning scale along with other hyperparameters. We present specific measurements of accuracy that can be useful for planning of experiments in the specified research area. 相似文献
108.
Stanisaw Kozdrowski Pawe Cichosz Piotr Paziewski Sawomir Sujecki 《Entropy (Basel, Switzerland)》2021,23(1)
Increasing demand in the backbone Dense Wavelength Division (DWDM) Multiplexing network traffic prompts an introduction of new solutions that allow increasing the transmission speed without significant increase of the service cost. In order to achieve this objective simpler and faster, DWDM network reconfiguration procedures are needed. A key problem that is intrinsically related to network reconfiguration is that of the quality of transmission assessment. Thus, in this contribution a Machine Learning (ML) based method for an assessment of the quality of transmission is proposed. The proposed ML methods use a database, which was created only on the basis of information that is available to a DWDM network operator via the DWDM network control plane. Several types of ML classifiers are proposed and their performance is tested and compared for two real DWDM network topologies. The results obtained are promising and motivate further research. 相似文献
109.
Stephen Fox 《Entropy (Basel, Switzerland)》2021,23(2)
Active inference is a physics of life process theory of perception, action and learning that is applicable to natural and artificial agents. In this paper, active inference theory is related to different types of practice in social organization. Here, the term social organization is used to clarify that this paper does not encompass organization in biological systems. Rather, the paper addresses active inference in social organization that utilizes industrial engineering, quality management, and artificial intelligence alongside human intelligence. Social organization referred to in this paper can be in private companies, public institutions, other for-profit or not-for-profit organizations, and any combination of them. The relevance of active inference theory is explained in terms of variational free energy, prediction errors, generative models, and Markov blankets. Active inference theory is most relevant to the social organization of work that is highly repetitive. By contrast, there are more challenges involved in applying active inference theory for social organization of less repetitive endeavors such as one-of-a-kind projects. These challenges need to be addressed in order for active inference to provide a unifying framework for different types of social organization employing human and artificial intelligence. 相似文献
110.
Jon Mallatt 《Entropy (Basel, Switzerland)》2021,23(6)
This paper assesses two different theories for explaining consciousness, a phenomenon that is widely considered amenable to scientific investigation despite its puzzling subjective aspects. I focus on Integrated Information Theory (IIT), which says that consciousness is integrated information (as ϕMax) and says even simple systems with interacting parts possess some consciousness. First, I evaluate IIT on its own merits. Second, I compare it to a more traditionally derived theory called Neurobiological Naturalism (NN), which says consciousness is an evolved, emergent feature of complex brains. Comparing these theories is informative because it reveals strengths and weaknesses of each, thereby suggesting better ways to study consciousness in the future. IIT’s strengths are the reasonable axioms at its core; its strong logic and mathematical formalism; its creative “experience-first” approach to studying consciousness; the way it avoids the mind-body (“hard”) problem; its consistency with evolutionary theory; and its many scientifically testable predictions. The potential weakness of IIT is that it contains stretches of logic-based reasoning that were not checked against hard evidence when the theory was being constructed, whereas scientific arguments require such supporting evidence to keep the reasoning on course. This is less of a concern for the other theory, NN, because it incorporated evidence much earlier in its construction process. NN is a less mature theory than IIT, less formalized and quantitative, and less well tested. However, it has identified its own neural correlates of consciousness (NCC) and offers a roadmap through which these NNCs may answer the questions of consciousness using the hypothesize-test-hypothesize-test steps of the scientific method. 相似文献