全文获取类型
收费全文 | 11470篇 |
免费 | 892篇 |
国内免费 | 538篇 |
专业分类
电工技术 | 667篇 |
技术理论 | 1篇 |
综合类 | 723篇 |
化学工业 | 1912篇 |
金属工艺 | 547篇 |
机械仪表 | 754篇 |
建筑科学 | 759篇 |
矿业工程 | 410篇 |
能源动力 | 301篇 |
轻工业 | 694篇 |
水利工程 | 192篇 |
石油天然气 | 853篇 |
武器工业 | 92篇 |
无线电 | 1255篇 |
一般工业技术 | 1412篇 |
冶金工业 | 629篇 |
原子能技术 | 125篇 |
自动化技术 | 1574篇 |
出版年
2024年 | 62篇 |
2023年 | 212篇 |
2022年 | 344篇 |
2021年 | 490篇 |
2020年 | 390篇 |
2019年 | 362篇 |
2018年 | 359篇 |
2017年 | 367篇 |
2016年 | 337篇 |
2015年 | 446篇 |
2014年 | 553篇 |
2013年 | 633篇 |
2012年 | 763篇 |
2011年 | 746篇 |
2010年 | 681篇 |
2009年 | 678篇 |
2008年 | 608篇 |
2007年 | 608篇 |
2006年 | 657篇 |
2005年 | 510篇 |
2004年 | 364篇 |
2003年 | 304篇 |
2002年 | 300篇 |
2001年 | 260篇 |
2000年 | 266篇 |
1999年 | 289篇 |
1998年 | 236篇 |
1997年 | 213篇 |
1996年 | 187篇 |
1995年 | 157篇 |
1994年 | 130篇 |
1993年 | 82篇 |
1992年 | 74篇 |
1991年 | 57篇 |
1990年 | 52篇 |
1989年 | 34篇 |
1988年 | 21篇 |
1987年 | 19篇 |
1986年 | 20篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
利用GPRS和Internet技术,在μC/OS-Ⅱ嵌入式实时操作系统环境下,实现船载远程监控系统中船载监控终端的设计.主要介绍系统总体和功能设计,详细介绍船载监控系统终端的软、硬件设计及调试,验证基于GPRS的船载远程监控系统的可行性,为船舶远程作业的实时控制提供一种有效的方法. 相似文献
992.
制作了反向饱和电流为5.5×10-14 A/cm2,势垒高度为1.18eV的GaN肖特基势垒紫外探测器.测量了探测器分别在零偏压及反向偏压下的光谱响应度,响应度随反向偏压无显著变化,零偏压下峰值响应度在波长358.2nm处达到了0.214A/W.利用波长359nm光束横向扫描探测器的光敏面,测量了探测器在不同偏压下的空间响应均匀性,相应偏压下的光响应在光敏面中央范围内响应幅值变化不超过0.6%.光子能量在禁带边沿附近的光束照射下,GaN肖特基势垒紫外探测器存在势垒高度显著降低现象,这种现象在肖特基透明电极边沿及其压焊电极附近表现得更为突出.探测器在368和810nm波长光一起照射时的开路电压比只有368nm光照射时的开路电压大,而零偏压下两者的光电流近似相等.利用这种开路电压变化效应估算了探测器在368nm光照射下,表面被俘获空穴的面密度变化量约为8.4×1010 cm-2. 相似文献
993.
994.
The fabrication of hierarchically structured Ni(OH)2 monolayer hollow‐sphere arrays with the shell composed of building blocks of nanoflakelets is reported on p. 644 by Weiping Cai and co‐workers. The morphology can be easily controlled by the synthesis parameters, and the arrays show a tunable optical transmission stop band. Tuning can be achieved by changing the size or morphology of the hollow spheres. Such arrays may have potential applications in optical devices, photonic crystals, and as sensors for gas detection. The fabrication of a hierarchically structured Ni(OH)2 monolayer hollow‐sphere array with the shell composed of building blocks of nanoflakelets is demonstrated based on a colloidal monolayer and electrochemical deposition. The morphology can be easily controlled by the colloidal monolayer and deposition parameters. Importantly, such monolayer hollow‐sphere array shows a morphology‐ and size‐dependent tunable optical transmission stop band. This stop band can be easily tuned from 455–1855 nm by changing the size of the hollow spheres between 1000 and 4500 nm, and also fine‐adjusted by changing the deposition time. The array exhibits a nearly incident‐angle‐independent position of the stop band that 3D photonic crystals do not possess. This structure may have potential applications in optical devices, photonic crystals, and sensors for gas detection. 相似文献
995.
In this paper, explicit parametric solutions to the generalized Sylvester matrix equation AX ‐ XF = BY and the regulator matrix equation AX ‐ XF = BY + R are proposed without any transformation and factorization. The proposed solutions are presented in terms of the Krylov matrix of matrix pair (A, B), a symmetric operator and the generalized observability matrix of matrix pair (Z, F) where Z is an arbitrary matrix and is used to denote the degree of freedom in the solution. Due to its elegant form and convenient computation, these proposed solutions will play an important role in solving and analyzing these types of equations in control systems theory. 相似文献
996.
Electric Potential in a Dielectric Sphere Head Produced by a Time-Harmonic Equivalent Current Dipole
Xiao-Yong Duan Shi-Zheng Peng Long-Wu Li Xiao-Chun Liu Rong Xin 《中国电子科技》2007,5(3):268-271
A time-harmonic equivalent current dipole model is proposed to simulate EEG source which deals with the problem concerning the capacitance effect. The expressions of potentials in both homogeneous infinite dielectric medium and dielectric sphere on the electroquasistatic condition are presented. The potential in a 3-layer inhomogeneous spherical head is computed by using this model. The influences on potential produced by time-harmonic character and permittivity are discussed. The results show that potentials in dielectric sphere are affected by frequency and permittivity. 相似文献
997.
998.
Metal‐Organic Frameworks: Bimetallic Metal‐Organic Frameworks: Probing the Lewis Acid Site for CO2 Conversion (Small 17/2016) 下载免费PDF全文
999.
This article addresses an iterative learning control (ILC) design for a class of linear discrete-time systems with multiple time delays. In order to improve the tracking performance, we introduce a P-type high-order iterative learning algorithm that makes use of information from several previous iterations. An initial state learning scheme is proposed to eliminate the effect of the initialization error on the final tracking error. Furthermore, we establish a sufficient condition to ensure asymptotic convergence. A simulation example is also provided to illustrate the effectiveness of the proposed result. 相似文献
1000.