全文获取类型
收费全文 | 50861篇 |
免费 | 4815篇 |
国内免费 | 2665篇 |
专业分类
电工技术 | 2794篇 |
技术理论 | 6篇 |
综合类 | 3487篇 |
化学工业 | 8416篇 |
金属工艺 | 3098篇 |
机械仪表 | 3069篇 |
建筑科学 | 3913篇 |
矿业工程 | 1409篇 |
能源动力 | 1573篇 |
轻工业 | 4159篇 |
水利工程 | 1069篇 |
石油天然气 | 2799篇 |
武器工业 | 417篇 |
无线电 | 5859篇 |
一般工业技术 | 6104篇 |
冶金工业 | 2356篇 |
原子能技术 | 633篇 |
自动化技术 | 7180篇 |
出版年
2024年 | 260篇 |
2023年 | 881篇 |
2022年 | 1567篇 |
2021年 | 2149篇 |
2020年 | 1735篇 |
2019年 | 1426篇 |
2018年 | 1655篇 |
2017年 | 1751篇 |
2016年 | 1602篇 |
2015年 | 2099篇 |
2014年 | 2538篇 |
2013年 | 3357篇 |
2012年 | 3472篇 |
2011年 | 3552篇 |
2010年 | 3292篇 |
2009年 | 3172篇 |
2008年 | 3025篇 |
2007年 | 2965篇 |
2006年 | 2853篇 |
2005年 | 2359篇 |
2004年 | 1691篇 |
2003年 | 1603篇 |
2002年 | 1643篇 |
2001年 | 1423篇 |
2000年 | 1094篇 |
1999年 | 1033篇 |
1998年 | 798篇 |
1997年 | 628篇 |
1996年 | 578篇 |
1995年 | 479篇 |
1994年 | 381篇 |
1993年 | 263篇 |
1992年 | 233篇 |
1991年 | 158篇 |
1990年 | 122篇 |
1989年 | 93篇 |
1988年 | 81篇 |
1987年 | 61篇 |
1986年 | 40篇 |
1985年 | 42篇 |
1984年 | 38篇 |
1983年 | 26篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1978年 | 6篇 |
1973年 | 5篇 |
1959年 | 10篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Homogeneous and nano-sized BPNT [(Ba1-xPbx)Nd2Ti5O14] powders were prepared under various hydrothermal conditions. Crystallinity and homogeneity of the synthetic powders were
investigated. The microwave dielectric properties of the filters prepared with hydrothermal powders were compared with those
of the filters prepared with conventional powders. The microwave dielectric properties of the filter prepared with the hydrothermal
powders were also better than those of the filter manufactured with the conventional powders. The dielectric constant, quality
constant and temperature coefficient of resonance frequency of hydrothermally prepared filter under optimum condition and
measured at 3.5 GHz around were about 93, 6067 and 0 ppm/°C, respectively. 相似文献
82.
Sangseok Yun Bongjin Jun Daijin Kim Jaewoong Kim Sukhan Lee Mun-Taek Choi Munsang Kim Joong-Tae Park Jae-Bok Song 《Journal of Intelligent and Robotic Systems》2012,67(2):79-99
This paper describes a scheme for proactive human search for a designated person in an undiscovered indoor environment without human operation or intervention. In designing and developing human identification with prior information a new approach that is robust to illumination and distance variations in the indoor environment is proposed. In addition, a substantial exploration method with an octree structure, suitable for path planning in an office configuration, is employed. All these functionalities are integrated in a message- and component-based architecture for the efficient integration and control of the system. This approach is demonstrated by succeeding human search in the challenging robot mission of the 2009 Robot Grand Challenge Contest. 相似文献
83.
With the development of cloud environments serving as a unified infrastructure, the resource management and energy consumption issues become more important in the operations of such systems. In this paper, we investigate adaptive model-free approaches for resource allocation and energy management under time-varying workloads and heterogeneous multi-tier applications. Specifically, we make use of measurable metrics, including throughput, rejection amount, queuing state, and so on, to design resource adjustment schemes and to make control decisions adaptively. The ultimate objective is to guarantee the summarized revenue of the resource provider while saving energy and operational costs. To validate the effectiveness, performance evaluation experiments are performed in a simulated environment, with realistic workloads considered. Results show that with the combination of long-term adaptation and short-term adaptation, the fluctuation of unpredictable workloads can be captured, and thus the total revenue can be preserved while balancing the power consumption as needed. Furthermore, the proposed approach can achieve better effect and efficiency than the model-based approaches in dealing with real-world workloads. 相似文献
84.
85.
赵云 《徐州建筑职业技术学院学报》2013,13(1):71-72
以实用英语教材中的课文为例,分析了语篇模式在高职英语教学中的应用.在此基础上阐释了语篇模式教学在高职英语教学中的优势,即有利于把握篇彰结构,理解篇章内容,认识词汇变化形态,进而有效提取关键信息,不断提高写作水平. 相似文献
86.
The work presented in this paper focuses on improving coal loading performance of shear drum.Employing the similarity theory,we carried out a dimensional analysis of the correlation parameters which in... 相似文献
87.
玻璃网格板是一种相互垂直的纵、横刻线的二维线纹标准器,用来检测航测仪器、遥感仪器和各类二维坐标测量仪器的精度,因此,它的精度直接影响待检仪器的精度。结合计量圆光栅的制作工艺,详细介绍了基于光刻胶的玻璃网格板新型制作工艺,检验结果表明该种工艺制作的玻璃网格板线条均匀,280mm内刻线间距精度小于1μm。 相似文献
88.
通过分析霍桑短篇小说《自我主义;或心底之蛇》中"蛇"的隐喻义,聚焦于作者的罪恶观,并阐释这种罪恶存在的根源、危害及其救赎良方。 相似文献
89.
陆韵 《吉林化工学院学报》2012,29(4):64-66
校园文化是思想政治教育重要的载体,具有育人导向、渗透和熏陶、约束、规范和传承、融合、创新文化等功能,本文依据时代的特征,从"两课"进网络文化、加强对校园文化活动的思想导向;结合本院社团文化活动的实际,阐述了对校园文化思想政治功能实现问题的看法。 相似文献
90.
SungHoo Choi Jong Pil Yun Keunhwi Koo Sang Woo Kim 《Expert systems with applications》2012,39(9):7621-7636
This paper deals with algorithms for text localization and character segmentation in images for process automation in the steel-making industry. Each character which comprises slab identification numbers may be corrupted severely before it is captured by network cameras. Therefore, proper processing is required to localize the target texts successfully. In this paper, we propose (1) a method to evaluate the closeness of an edge patch to the form of a closed contour, (2) an edge inspection method to determine character colors and estimate font thickness, and (3) three reasonable binarization methods to increase the performance of the algorithm for the detection of the left and right boundaries of the text rectangle. The experimental results show that the proposed algorithms are reliable. 相似文献