全文获取类型
收费全文 | 78619篇 |
免费 | 6159篇 |
国内免费 | 3131篇 |
专业分类
电工技术 | 5329篇 |
技术理论 | 1篇 |
综合类 | 8088篇 |
化学工业 | 4665篇 |
金属工艺 | 2647篇 |
机械仪表 | 3896篇 |
建筑科学 | 12174篇 |
矿业工程 | 2167篇 |
能源动力 | 1231篇 |
轻工业 | 12854篇 |
水利工程 | 3649篇 |
石油天然气 | 2571篇 |
武器工业 | 499篇 |
无线电 | 5995篇 |
一般工业技术 | 3593篇 |
冶金工业 | 3699篇 |
原子能技术 | 350篇 |
自动化技术 | 14501篇 |
出版年
2024年 | 183篇 |
2023年 | 881篇 |
2022年 | 1549篇 |
2021年 | 2103篇 |
2020年 | 2037篇 |
2019年 | 1693篇 |
2018年 | 1497篇 |
2017年 | 1912篇 |
2016年 | 2120篇 |
2015年 | 2570篇 |
2014年 | 5447篇 |
2013年 | 4333篇 |
2012年 | 5686篇 |
2011年 | 6242篇 |
2010年 | 4865篇 |
2009年 | 5073篇 |
2008年 | 4803篇 |
2007年 | 5725篇 |
2006年 | 5103篇 |
2005年 | 4295篇 |
2004年 | 3681篇 |
2003年 | 3407篇 |
2002年 | 2877篇 |
2001年 | 2191篇 |
2000年 | 1745篇 |
1999年 | 1299篇 |
1998年 | 881篇 |
1997年 | 715篇 |
1996年 | 614篇 |
1995年 | 527篇 |
1994年 | 394篇 |
1993年 | 314篇 |
1992年 | 244篇 |
1991年 | 174篇 |
1990年 | 111篇 |
1989年 | 120篇 |
1988年 | 89篇 |
1987年 | 78篇 |
1986年 | 46篇 |
1985年 | 48篇 |
1984年 | 44篇 |
1983年 | 46篇 |
1982年 | 29篇 |
1981年 | 18篇 |
1980年 | 25篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 14篇 |
1976年 | 6篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
31.
通过有限元仿真软件Autoform分析了热冲压过程中工艺参数的变化对22MnB5马氏体钢B柱起皱、回弹、减薄、马氏体量以及强度的影响。结果表明:22MnB5马氏体钢B柱热冲压最优化工艺参数为加热温度930 ℃,冷却速率80 ℃/s。该工艺参数下,热冲压过程各处均完成马氏体转变,硬度分布均匀,材料减薄率较低,热冲压成形效果好,尺寸精度高,冲压件强度均大于1400 MPa。 相似文献
32.
Deep learning has gained a significant popularity in recent years thanks to its tremendous success across a wide range of relevant fields of applications, including medical image analysis domain in particular. Although convolutional neural networks (CNNs) based medical applications have been providing powerful solutions and revolutionizing medicine, efficiently training of CNNs models is a tedious and challenging task. It is a computationally intensive process taking long time and rare system resources, which represents a significant hindrance to scientific research progress. In order to address this challenge, we propose in this article, R2D2, a scalable intuitive deep learning toolkit for medical imaging semantic segmentation. To the best of our knowledge, the present work is the first that aims to tackle this issue by offering a novel distributed versions of two well-known and widely used CNN segmentation architectures [ie, fully convolutional network (FCN) and U-Net]. We introduce the design and the core building blocks of R2D2. We further present and analyze its experimental evaluation results on two different concrete medical imaging segmentation use cases. R2D2 achieves up to 17.5× and 10.4× speedup than single-node based training of U-Net and FCN, respectively, with a negligible, though still unexpected segmentation accuracy loss. R2D2 offers not only an empirical evidence and investigates in-depth the latest published works but also it facilitates and significantly reduces the effort required by researchers to quickly prototype and easily discover cutting-edge CNN configurations and architectures. 相似文献
33.
当今的多相催化研究需要新的技术和方法从原子尺度上表征活性中心结构和反应中间体。本文作者课题组近期开发了理论模拟新技术来探索催化剂活性位点结构,即基于神经网络势函数的大规模原子模拟(LASP)软件中实现的全局神经网络势函数计算方法。本文介绍了该方法可以显著降低催化体系的计算代价,而维持与密度泛函理论同一级别的计算精度,从而解决多相催化中的许多复杂问题。本文对神经网络势函数方法的实现细节和目前已实现的应用场景进行了详细介绍。神经网络势函数可以用来预测材料晶体结构,理解高压氢化条件下TiO2表面的结构演化和确定三元氧化物ZnCrO晶相中合成气制甲醇活性位点。最后文章分析了神经网络势函数的局限性和今后可能的三个研究方向,即材料性质预测、多元素体系神经网络势函数构造和化学反应拟合。 相似文献
34.
薛元昕 《上海第二工业大学学报》2018,(4):292-296
将习近平总书记“精准扶贫” 的重要思想应用于高等学校教学辅导答疑工作中, 明确了高校教师辅导答疑工
作的目的、内容和措施。针对大学生在学习、生活过程中遇到的各种问题以及个性化需求, 将辅导答疑的类型分成
5 种形式, 实施精准辅导答疑, 提高人才培养质量。 相似文献
35.
针对无人机控制站难以与多型无人机互联互通的问题,从通用控制软件的角度开展研究,分析了设计需求,提出了一种采用平台+插件的软件架构,并分析了软件架构、基于XML技术的帧格式信号和参数信息描述、动态报文解析和组包、软件界面定制等关键技术。在车载控制站和便携控制站的工程验证表明,所提解决方案实现了对多型无人机的控制,具有良好的通用性、扩展性,并支持用户自定义对外通信协议和人机交互功能、界面。 相似文献
36.
37.
为实现对干湿联合冷却塔冷却特性、节水特性的综合分析,编制干湿联合冷却塔校核计算流程,基于Visual Studio开发平台,本文开发了干湿联合冷却塔冷却节水特性分析优化软件。通过对某在运干湿联合冷却塔进行冷却节水特性计算,验证了所开发软件计算结果的准确性;在消雾节水计算结果基础上,对标干湿联合消雾冷却塔验收测试规程,生成其成雾频率曲线、耗水量曲线、塔雾指数、冷却特性曲线,综合分析其消雾特性、节水特性及冷却特性,从而确定了干湿联合冷却塔的最佳运行工况。同时运用所开发软件对比分析了某冷却塔设计干段散热面积对其消雾特性、节水特性及冷却特性的耦合影响,并分析了百叶窗开度对干湿联合冷却塔性能的影响,为干湿联合冷却塔的运行优化和设计优化提供了工具性软件支持。 相似文献
38.
Simulation of multi-engineering systems typically requires many issues to be solved, which are to be addressed by developing appropriate modeling and simulation programming techniques. In the last years, the authors have participated in several studies in which they analyzed in detail electrified railway systems and simulated them using Modelica language. After a few years of study, despite the huge complexity of these systems, it has appeared evident that Modelica language is very well suited and able to effectively solve the typical issues they present. While specific railway system simulations have already been discussed in specific papers, whose focus was on application and actual results, in this paper, the authors show how to use Modelica language to solve specific modeling issues through suitable programming techniques. Moreover, the issues to be solved and the conceived techniques may be interpreted in a general way and to be applied also in different engineering domains. Finally, this paper briefly recalls the principal results obtained in previous specific papers, in which these techniques were fully implemented. 相似文献
39.
40.
The rapid development of the construction industry in China has introduced unprecedented quality-related problems in the country’s building industry. In response to this issue, the government has established various complaint channels to report quality problems. Therefore, building quality complaints (BQCs) need to be classified and solved by respective agencies or departments rapidly for avoiding adverse impact on the safety, health, and well-being of people. However, the current process of classifying BQCs is labor intensive, time consuming, and error prone. An automatic complaint classification is required to improve the effectiveness and efficiency of complaint handling, but studies on this issue are limited. Prevailing text classification research in construction has focused on utilizing conventional shallow machine learning. By contrast, this study explores a novel convolutional neural network (CNN)-based approach that incorporates a deep-learning method to automatically classify the short texts contained within BQCs. The presented approach enables capturing the semantic features in BQC texts and automatic classification of the BQCs into predefined categories. After the model optimization, tests are conducted to examine the practical application of the text classification approach compared with Bayes-based and support vector machine classifiers. Results indicate that the developed CNN-based approach performs well in the Chinese BQC classification with limited manual intervention and few complicated feature engineering. 相似文献