全文获取类型
收费全文 | 266381篇 |
免费 | 30224篇 |
国内免费 | 18289篇 |
专业分类
电工技术 | 27965篇 |
技术理论 | 20篇 |
综合类 | 29723篇 |
化学工业 | 19720篇 |
金属工艺 | 8840篇 |
机械仪表 | 20457篇 |
建筑科学 | 25307篇 |
矿业工程 | 8951篇 |
能源动力 | 9548篇 |
轻工业 | 13844篇 |
水利工程 | 9276篇 |
石油天然气 | 9847篇 |
武器工业 | 2932篇 |
无线电 | 30217篇 |
一般工业技术 | 20271篇 |
冶金工业 | 8100篇 |
原子能技术 | 2744篇 |
自动化技术 | 67132篇 |
出版年
2024年 | 675篇 |
2023年 | 3880篇 |
2022年 | 7634篇 |
2021年 | 9090篇 |
2020年 | 9302篇 |
2019年 | 7277篇 |
2018年 | 6666篇 |
2017年 | 8166篇 |
2016年 | 9443篇 |
2015年 | 10414篇 |
2014年 | 17591篇 |
2013年 | 16690篇 |
2012年 | 20436篇 |
2011年 | 21984篇 |
2010年 | 16320篇 |
2009年 | 16816篇 |
2008年 | 16354篇 |
2007年 | 19114篇 |
2006年 | 16355篇 |
2005年 | 14067篇 |
2004年 | 11784篇 |
2003年 | 10234篇 |
2002年 | 8157篇 |
2001年 | 6741篇 |
2000年 | 5494篇 |
1999年 | 4476篇 |
1998年 | 3579篇 |
1997年 | 2966篇 |
1996年 | 2458篇 |
1995年 | 2049篇 |
1994年 | 1725篇 |
1993年 | 1262篇 |
1992年 | 1075篇 |
1991年 | 774篇 |
1990年 | 635篇 |
1989年 | 550篇 |
1988年 | 439篇 |
1987年 | 291篇 |
1986年 | 257篇 |
1985年 | 245篇 |
1984年 | 270篇 |
1983年 | 256篇 |
1982年 | 215篇 |
1981年 | 104篇 |
1980年 | 97篇 |
1979年 | 73篇 |
1978年 | 55篇 |
1977年 | 49篇 |
1976年 | 43篇 |
1959年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
5G蜂窝网络发展迅猛,其覆盖面积将逐渐增大,因此使用5G蜂窝网络进行定位是有研究潜力的研究方向。本文提出一种新的深度学习技术来实现高效、高精度和低占用的定位,以代替传统指纹定位过程中繁重的指纹库生成以及距离计算。该方法建立了一个特殊的卷积神经网络,并根据5G天线信号的接收信号强度指示、相位和到达角等特征量,选择合适的输入数据格式构造样本组建训练集,对该卷积神经网络进行训练。训练得到的卷积神经网络可以替代指纹定位中的庞大指纹库,非常有利于直接在5G移动设备端实现定位。虽然卷积神经网络在训练过程中需要大量时间,但在训练完毕后直接进行分类定位的速度非常快,可以保障定位实现的实时性。本文所实现的卷积神经网络权重与偏置所占内存不到0.5 MB,且能够在实际应用环境中以95%的定位准确率以及0.1 m的平均定位精度实现高精度定位。 相似文献
63.
本文主要总结了新冠疫情期间作者的电磁场理论课程在线教学经验。对比分析了录播和直播的优缺点后,选择录播教学方式。基于超星网络教学平台,展示了录播网络教学的具体措施,包括网上答疑和学习效果检查以及在线批改作业等。给出了网络教学可以为线下教学继续使用的方法和手段,为疫情结束后的正常教学提供了新的网络教学补充措施。 相似文献
64.
摘 要:核心网业务模型的建立是5G网络容量规划和网络建设的基础,通过现有方法得到的理论业务模型是静态不可变的且与实际网络存在偏离。为了克服现有5G核心网业务模型与现网模型适配性较差以及规划设备无法满足用户实际业务需求的问题,提出了一种长短期记忆(long short-term memory,LSTM)网络与卷积LSTM (convolution LSTM,ConvLSTM)网络双通道融合的 5G 核心网业务模型预测方法。该方法基于人工智能(artificial intelligence,AI)技术以实现高质量的核心网业务模型的智能预测,形成数据反馈闭环,实现网络自优化调整,助力网络智能化建设。 相似文献
65.
66.
In this paper, we strive to propose a self-interpretable framework, termed PrimitiveTree, that incorporates deep visual primitives condensed from deep features with a conventional decision tree, bridging the gap between deep features extracted from deep neural networks (DNNs) and trees’ transparent decision-making processes. Specifically, we utilize a codebook, which embeds the continuous deep features into a finite discrete space (deep visual primitives) to distill the most common semantic information. The decision tree adopts the spatial location information and the mapped primitives to present the decision-making process of the deep features in a tree hierarchy. Moreover, the trained interpretable PrimitiveTree can inversely explain the constituents of the deep features, highlighting the most critical and semantic-rich image patches attributing to the final predictions of the given DNN. Extensive experiments and visualization results validate the effectiveness and interpretability of our method. 相似文献
67.
针对光谱反射率研究中因训练样本数据量大造成的冗杂等问题,提出了一种基于RGB信息进行聚类的样本分类方法。首先对颜色进行聚类并确定聚类个数,后对每一类光谱反射率使用BP神经网络分别进行重建。对于实验结果,使用ΔE00、均方根误差(RMSE)以及适应度系数等标准进行评价,同时与主成分分析算法进行对比。从实验分析可得出,在聚类数目为7时光谱反射率重建效果最好,这时的平均CIE2000的色差为0.836,平均RMSE为0.0149,平均适应度系数为99.82%,并且,在最后对重建色差较大的色块进行了优化处理。实验证明,颜色聚类方法可以很好的应用于光谱反射率重建。 相似文献
68.
《International Journal of Hydrogen Energy》2022,47(45):19718-19731
Metals and alloys forming reversible hydrides with hydrogen gas are potential building blocks for compact, solid state hydrogen storage systems. Based on the materials’ thermodynamic characteristics, their use as temperature-swing gas compression and delivery systems in the hydrogen economy is also possible. Given the wide variety of materials developed and tested at laboratory and pilot scales, a harmonized method of selecting the feasible material(s) for a particular real-life application is required. This study proposes a system selection framework based on a normalized, multi-criteria metric. Using calculated values of multi-criteria metric, multi-criteria screening and ranking of potential materials has been demonstrated for a particular use case. It is found that the alloy TiMn1.52 having value of additive metric between 0.25 and 0.35 represents the best material for a single stage system. The alloy pair CaNi5–Ti1.5CrMn represents the best alternative for a two-stage system with additive metric values between 0.63 and 0.82. Energy and economic characteristics of the metal hydride gas compression and delivery systems are evaluated and compared with an equivalent mechanical compression system producing the same final effect (i.e., delivery of a given quantity of gas at a defined pressure). 相似文献
69.
《International Journal of Hydrogen Energy》2022,47(100):42280-42292
In this study, the separation of hydrogen from gas mixtures using a palladium membrane coupled with a vacuum environment on the permeate side was studied experimentally. The gas mixtures composed of H2, N2, and CO2 were used as the feed. Hydrogen permeation fluxes were measured with membrane operating temperature in the range of 320–380 °C, pressures on the retentate side in the range of 2–5 atm, and vacuum pressures on the permeate side in the range of 15–51 kPa. The Taguchi method was used to design the operating conditions for the experiments based on an orthogonal array. Using the measured H2 permeation fluxes from the Taguchi approach, the stepwise regression analysis was also employed for establishing the prediction models of H2 permeation flux, followed by the analysis of variance (ANOVA) to identify the significance and suitability of operating conditions. Based on both the Taguchi approach and ANOVA, the H2 permeation flux was mostly affected by the gas mixture composition, followed by the retentate side pressure, the vacuum degree, and the membrane temperature. The predicted optimal operating conditions were the gas mixture with 75% H2 and 25% N2, the membrane temperature of 320 °C, the retentate side pressure of 5 atm, and the vacuum degree of 51 kPa. Under these conditions, the H2 permeation flux was 0.185 mol s?1 m?2. A second-order normalized regression model with a relative error of less than 7% was obtained based on the measured H2 permeation flux. 相似文献
70.
Shu-Hung Yang Yi-Nan Lin Cheng-Ying Yang Ming-Kuen Chen Victor R. L. Shen Yu-Wei Lin 《电子科技学刊:英文版》2022,20(2):209-223
An increasing number of social media and networking platforms have been widely used. People usually post the online comments to share their own opinions on the networking platforms with social media. Business companies are increasingly seeking effective ways to mine what people think and feel regarding their products and services. How to correctly understand the online customers’ reviews becomes an important issue. This study aims to propose a method with the aspect-oriented Petri nets (AOPN) to improve the examination correctness without changing any process and program. We collect those comments from the online reviews with Scrapy tools, perform sentiment analysis using SnowNLP, and examine the analysis results to improve the correctness. In this paper, we apply our method for a case of the online movie comments. The experimental results have shown that AOPN is helpful for the sentiment analysis and verifying its correctness. 相似文献