全文获取类型
收费全文 | 59418篇 |
免费 | 5565篇 |
国内免费 | 3058篇 |
专业分类
电工技术 | 4198篇 |
技术理论 | 5篇 |
综合类 | 4164篇 |
化学工业 | 9209篇 |
金属工艺 | 3538篇 |
机械仪表 | 3482篇 |
建筑科学 | 5209篇 |
矿业工程 | 1564篇 |
能源动力 | 1776篇 |
轻工业 | 3791篇 |
水利工程 | 1067篇 |
石油天然气 | 3162篇 |
武器工业 | 502篇 |
无线电 | 7297篇 |
一般工业技术 | 7310篇 |
冶金工业 | 2553篇 |
原子能技术 | 770篇 |
自动化技术 | 8444篇 |
出版年
2024年 | 314篇 |
2023年 | 1101篇 |
2022年 | 1762篇 |
2021年 | 2576篇 |
2020年 | 1848篇 |
2019年 | 1529篇 |
2018年 | 1734篇 |
2017年 | 1934篇 |
2016年 | 1716篇 |
2015年 | 2344篇 |
2014年 | 2823篇 |
2013年 | 3471篇 |
2012年 | 3755篇 |
2011年 | 3989篇 |
2010年 | 3618篇 |
2009年 | 3357篇 |
2008年 | 3479篇 |
2007年 | 3319篇 |
2006年 | 3337篇 |
2005年 | 2816篇 |
2004年 | 1993篇 |
2003年 | 1802篇 |
2002年 | 1897篇 |
2001年 | 1689篇 |
2000年 | 1468篇 |
1999年 | 1561篇 |
1998年 | 1153篇 |
1997年 | 1015篇 |
1996年 | 994篇 |
1995年 | 811篇 |
1994年 | 667篇 |
1993年 | 490篇 |
1992年 | 437篇 |
1991年 | 322篇 |
1990年 | 216篇 |
1989年 | 181篇 |
1988年 | 158篇 |
1987年 | 100篇 |
1986年 | 65篇 |
1985年 | 56篇 |
1984年 | 34篇 |
1983年 | 23篇 |
1982年 | 32篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1959年 | 2篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
大脑神经元的活动是在复杂的生理学环境下工作的,而生理学环境中的噪声来源于多个方面.如何定量地正确评估神经系统中的噪声环境是神经信息处理的基本问题.本文通过神经能量的计算给出了噪声对神经元膜电位及对应的能量波形产生显著影响的临界值的估计范围,从而定义了神经元赖以活动的生理学意义上的噪声环境. 相似文献
942.
传统的C/S结构DCS火电控制系统设计方法,上位机与服务器通信中,服务器需要与多个操作员站通信,造成负荷过高;为解决这一问题,以和利时第五代DCS为基础,设计新一代基于B/S模式的DCS数据监控系统,以点对点模式完成通信;新一代系统中,服务器相对于每个操作员站都是独立的,克服当前系统同时通信高负荷的弊端;给出了关键的底层控制站信息采集模块和DP总线信息传递模块的详细设计方案以及相关的软件设计方案,并给出了关键的B/S结构的详细设计方案;实验结果表明,以B/S结构为基础的DCS数据监控系统测量结果误差小,上位机通信的时长不超过1s,服务器冗余重启切换不超过1.2s,优化效果较为明显。 相似文献
943.
944.
Qunfeng Zeng Zhao Wang Wanjun He Zeming Pang Zekun Ning Ruiquan Chen Chenjie Zheng Chao Yan Leilei Guo 《Advanced Engineering Materials》2023,25(17):2300228
Ti6Al4V alloy has good corrosion resistance due to the formation of the passive oxide films on the surface of Ti6Al4V alloy. However, Ti6Al4V alloy has poor tribocorrosion resistance in the seawater environment. Herein the present work, plasma electrolytic oxidation (PEO) with the electrolyte of glycerol and sodium borate is used to generate PEO coatings on the surface of Ti6Al4V alloy to improve its tribocorrosion properties. The microstructure and tribocorrosion properties of PEO coatings are investigated by using scanning electron microscopy, X-ray diffraction, and tribometer, respectively. The growth kinetics and the tribocorrosion mechanisms of PEO coatings are discussed in detail. It is shown in the results that PEO coatings deposited on the surface of Ti6Al4V alloy are composed of rutile and anatase phases. The surface hardness and thickness of PEO coatings are enhanced with the increase of the voltage and time. The wear rate of Ti6Al4V alloy with PEO coatings is significantly reduced in artificial seawater. 相似文献
945.
Driven by the visions of the Internet of Things (IoT), Artificial Intelligence (AI), and 5G communications, the Internet of Cultural Things (IoCT) realize the comprehensive interconnection among cultural products, cultural services, cultural resources, and cultural platforms, bringing individuals with richer humanistic experience, increasing economic benefits for the cultural sector, and promoting the development of cultural heritage protection and education. At present, IoCT has received widespread attention in both industry and academia. To explore new research opportunities and assist users in constructing suitable IoCT systems for specific applications, this survey provides a comprehensive overview of the IoCT components and key technologies. A comparison study of representative IoCT systems is presented according to their applicability. A general platform architecture of IoCT is proposed to link cultural objects with the internet and human. Finally, open issues for research challenges and future opportunities of IoCT are also studied in this paper. 相似文献
946.
Chenhui Zhang Chen Liu Junwei Zhang Youyou Yuan Yan Wen Yan Li Dongxing Zheng Qiang Zhang Zhipeng Hou Gen Yin Kai Liu Yong Peng Xi-Xiang Zhang 《Advanced materials (Deerfield Beach, Fla.)》2023,35(1):2205967
Room-temperature magnetic skyrmion materials exhibiting robust topological Hall effect (THE) are crucial for novel nano-spintronic devices. However, such skyrmion-hosting materials are rare in nature. In this study, a self-intercalated transition metal dichalcogenide Cr1+xTe2 with a layered crystal structure that hosts room-temperature skyrmions and exhibits large THE is reported. By tuning the self-intercalate concentration, a monotonic control of Curie temperature from 169 to 333 K and a magnetic anisotropy transition from out-of-plane to the in-plane configuration are achieved. Based on the intercalation engineering, room-temperature skyrmions are successfully created in Cr1.53Te2 with a Curie temperature of 295 K and a relatively weak perpendicular magnetic anisotropy. Remarkably, a skyrmion-induced topological Hall resistivity as large as ≈106 nΩ cm is observed at 290 K. Moreover, a sign reversal of THE is also found at low temperatures, which can be ascribed to other topological spin textures having an opposite topological charge to that of the skyrmions. Therefore, chromium telluride can be a new paradigm of the skyrmion material family with promising prospects for future device applications. 相似文献
947.
Yahuan Huan Tiantian Luo Xiaocang Han Jun Ge Fangfang Cui Lijie Zhu Jingyi Hu Feipeng Zheng Xiaoxu Zhao Lili Wang Jian Wang Yanfeng Zhang 《Advanced materials (Deerfield Beach, Fla.)》2023,35(1):2207276
Exploring new-type 2D magnetic materials with high magnetic transition temperature and robust air stability has attracted wide attention for developing innovative spintronic devices. Recently, intercalation of native metal atoms into the van der Waals gaps of 2D layered transition metal dichalcogenides (TMDs) has been developed to form 2D non-layered magnetic TMDs, while only succeeded in limited systems (e.g., Cr2S3, Cr5Te8). Herein, composition-controllable syntheses of 2D non-layered iron selenide nanosheets (25% Fe-intercalated triclinic Fe5Se8 and 50% Fe-intercalated monoclinic Fe3Se4) are firstly reported, via a robust chemical vapor deposition strategy. Specifically, the 2D Fe5Se8 exhibits intrinsic room-temperature ferromagnetic property, which is explained by the change of electron spin states from layered 1T'-FeSe2 to non-layered Fe-intercalated Fe5Se8 based on density functional theory calculations. In contrast, the ultrathin Fe3Se4 presents novel metallic features comparable with that of metallic TMDs. This work hereby sheds light on the composition-controllable synthesis and fundamental property exploration of 2D self-intercalation induced novel TMDs compounds, by propelling their application explorations in nanoelectronics and spintronics-related fields. 相似文献
948.
郑靖波 《安徽工业大学学报》1998,(1)
考虑的是拟线性退化抛物型方程组解的存在性和唯一性.对解的存在性证明,首先构造所研究问题的正则化问题,再对正则化问题的解进行一系列估计,利用Arzda-Ascoli定理证明原问题解的存在性.用能量方法证明解的唯一性. 相似文献
949.
证明断裂力学L积分方程的被积函数的散度等于零,将面积分转化为线积分,使求解问题的维数降低两维。利用边界轮廓法的结果,使平面断裂问题L积分的求解转化为边界点的位移和面力线性迭加,避免了求解数值积分。 相似文献
950.
依据GB7714-87《文后参考文献著录规则》,对390篇来稿所引用的参考文献进行统计,分析了几种不规范的著录方式,并给出正确的表达方法,可为科技论文写作者及科技期刊编缉提供参考。 相似文献