全文获取类型
收费全文 | 11460篇 |
免费 | 852篇 |
国内免费 | 519篇 |
专业分类
电工技术 | 665篇 |
技术理论 | 1篇 |
综合类 | 719篇 |
化学工业 | 1907篇 |
金属工艺 | 546篇 |
机械仪表 | 751篇 |
建筑科学 | 759篇 |
矿业工程 | 405篇 |
能源动力 | 300篇 |
轻工业 | 685篇 |
水利工程 | 192篇 |
石油天然气 | 851篇 |
武器工业 | 92篇 |
无线电 | 1249篇 |
一般工业技术 | 1393篇 |
冶金工业 | 628篇 |
原子能技术 | 125篇 |
自动化技术 | 1563篇 |
出版年
2024年 | 61篇 |
2023年 | 210篇 |
2022年 | 344篇 |
2021年 | 491篇 |
2020年 | 390篇 |
2019年 | 359篇 |
2018年 | 355篇 |
2017年 | 364篇 |
2016年 | 336篇 |
2015年 | 441篇 |
2014年 | 551篇 |
2013年 | 627篇 |
2012年 | 763篇 |
2011年 | 745篇 |
2010年 | 675篇 |
2009年 | 675篇 |
2008年 | 605篇 |
2007年 | 606篇 |
2006年 | 653篇 |
2005年 | 507篇 |
2004年 | 362篇 |
2003年 | 299篇 |
2002年 | 298篇 |
2001年 | 256篇 |
2000年 | 264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 | 1篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 8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
61.
Simplified Perovskite Solar Cell with 4.1% Efficiency Employing Inorganic CsPbBr3 as Light Absorber 下载免费PDF全文
Jialong Duan Yuanyuan Zhao Benlin He Qunwei Tang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(20)
Perovskite solar cells with cost‐effectiveness, high power conversion efficiency, and improved stability are promising solutions to the energy crisis and environmental pollution. However, a wide‐bandgap inorganic–semiconductor electron‐transporting layer such as TiO2 can harvest ultraviolet light to photodegrade perovskite halides, and the high cost of a state‐of‐the‐art hole‐transporting layer is an economic burden for commercialization. Here, the building of a simplified cesium lead bromide (CsPbBr3) perovskite solar cell with fluorine‐doped tin oxide (FTO)/CsPbBr3/carbon architecture by a multistep solution‐processed deposition technology is demonstrated, achieving an efficiency as high as 4.1% and improved stability upon interfacial modification by graphene quantum dots and CsPbBrI2 quantum dots. This work provides new opportunities of building next‐generation solar cells with significantly simplified processes and reduced production costs. 相似文献
62.
Mingjiang Xie Zhicheng Xu Shuyi Duan Zhengfang Tian Yu Zhang Kun Xiang Ming Lin Xuefeng Guo Weiping Ding 《Nano Research》2018,11(1):216-224
The growth of a Ni(OH)2 coating on conductive carbon substrates is an efficient way to address issues related to their poor conductivity in electrochemical capacitor applications. However, the direct growth of nickel hydroxide coatings on a carbon substrate is challenging, because the surfaces of these systems are not compatible and a preoxidation treatment of the conductive carbon substrate is usually required. Herein, we present a facile preoxidation-free approach to fabricate a uniform Ni(OH)2 coating on carbon nanosheets (CNs) by an ion-exchange reaction to achieve the in situ transformation of a MgO/C composite to a Ni(OH)2/C one. The obtained Ni(OH)2/CNs hybrids possess nanosheet morphology, a large surface area (278 m2/g), and homogeneous elemental distributions. When employed as supercapacitors in a three-electrode configuration, the Ni(OH)2/CNs hybrid achieves a large capacitance of 2,218 F/g at a current density of 1.0 A/g. Moreover, asymmetric supercapacitors fabricated with the Ni(OH)2/CNs hybrid exhibit superior supercapacitive performances, with a large capacity of 198 F/g, and high energy density of 56.7 Wh/kg at a power density of 4.0 kW/kg. They show excellent cycling stability with 93% capacity retention after 10,000 cycles, making the Ni(OH)2/CNs hybrid a promising candidate for practical applications in supercapacitor devices. 相似文献
63.
Daojin Zhou Zhao Cai Yongmin Bi Weiliang Tian Ma Luo Qian Zhang Qian Zhang Qixian Xie Jindi Wang Yaping Li Yun Kuang Xue Duan Michal Bajdich Samira Siahrostami Xiaoming Sun 《Nano Research》2018,11(3):1358-1368
Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotential of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. This increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process. 相似文献
64.
Shuangfei Cai Wei Xiao Haohong Duan Xixi Liang Chen Wang Rong Yang Yadong Li 《Nano Research》2018,11(12):6304-6315
When the dimensionality of layered compounds decreases to the physical limit, ultimate two-dimensional (2D) anisotropy and/or quantum confinement effects may lead to extraordinary physicochemical attributes. Here, we report single-layer Rh nanosheets (NSs) exhibiting ultrahigh peroxidase-like activity, far exceeding that of horseradish peroxidase (HRP) and of most known layered nanomaterial-based peroxidase mimics. Considering per NS as an active subunit, the Rh NSs displayed a catalytic rate constant (Kcat) as high as 4.45 × 105 s–1 to H2O2, two orders of magnitude higher than those of HRP and Rh nanoparticles. The high atom efficiency of the Rh NSs can be attributed to the full exposure of surface-active Rh atoms, which greatly facilitates electron transfer and formation of superoxide anions, representing reactive oxygen species in the catalytic process. As a proof-of-concept application, the Rh NSs were successfully used as peroxidase mimics for the colorimetric detection of H2O2 and xanthine, with high sensitivity and selectivity. Moreover, a simple, rapid, and sensitive Rh-based paper sensor for ascorbic acid was also developed. In summary, this work provides a novel example of single-layer metallic NSs for biosensing. 相似文献
65.
66.
Chun-Xia Dou Zhi-Sheng Duan Xing-Bei Jia Pei-Feng Niu 《International Journal of Control, Automation and Systems》2011,9(3):478-488
This study introduces delay independent decentralized guaranteed cost control design method based on two controller structures
for nonlinear uncertain interconnected large scale systems with time delays. First, a set of equivalent Takagi-Sugeno (T-S)
fuzzy models are extended to represent the systems. Then a decentralized state-feedback guaranteed cost performance controller
is proposed for the fuzzy systems. Based on delay independent Lyapunov functional approach, some sufficient conditions for
the existence of the controller can be cast into the feasible problem of LMIs irrespective of the sizes of the time delays
so that the system can be asymptotically stabilized for all considered uncertainties whose sizes are not larger than their
bounds. Finally, the minimizing approach is proposed to search the suboptimal upper bound value of guaranteed cost function.
Moreover, the corresponding conditions are extended into the generalized dynamic output-feedback close-loop system. Finally,
the better control performances of the proposed methods are shown by the simulation examples. 相似文献
67.
针对采用低成本惯性元件的MEMS-IMU/GPS组合导航系统在GPS信号长时间失效后系统趋于发散的问题,在研究捷联航姿解算算法、加速计测量姿态角算法和磁传感器解算航向角算法的基础上,提出将航姿辅助修正算法引入组合导航系统中,一旦系统检测到无效信号出现,则能自动切换到辅助修正状态,使导航结果被抑制在0.5°左右;通过半实物仿真实验,证明了该方法能够有效解决GPS信号长时间失效后系统发散问题,满足了在低成本MEMS惯性元件基础上的高精度导航要求。 相似文献
68.
This paper studies the problem of stabilizing a linear system with delayed and saturating feedback. It is known that the eigenstructure assignment‐based low‐gain feedback law (globally) stabilizes a linear system in the presence of arbitrarily large delay in its input, and semi‐globally stabilizes it when the input is also subject to saturation, as long as all its open‐loop poles are located in the closed left‐half plane. Based on a recently developed parametric Lyapunov equation‐based low‐gain feedback design method, this paper presents alternative, but simpler and more elegant, feedback laws that solve these problems. The advantages of this new approach include its simplicity, the capability of giving explicit conditions to guarantee the stability of the closed‐loop system, and the ease in scheduling the low‐gain parameter on line to achieve global stabilization in the presence of actuator saturation. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
69.
Bin Zhou Zhi-Bin Yan Guang-Ren Duan 《International Journal of Control, Automation and Systems》2010,8(1):29-35
The polynomial Diophantine matrix equation and the generalized Sylvester matrix equation are important for controller design
in frequency domain linear system theory and time domain linear system theory, respectively. By using the so-called generalized
Sylvester mapping, right coprime factorization and Bezout identity associated with certain polynomial matrices, we present
in this note a unified parametrization for the solutions to both of these two classes of matrix equations. Moreover, it is
shown that solutions to the generalized Sylvester matrix equation can be obtained if solutions to the Diophantine matrix equation
are available. The results disclose a relationship between the polynomial Diophantine matrix equation and generalized Sylvester
matrix equation that are respectively studied and used in frequency domain linear system theory and time domain linear system
theory. 相似文献
70.
提出了一种可重用的VXI系统的实现方法;该系统的硬件结构是使用PPC405GP和FPGA来实现,并采用了一种简单且通用的总线和功能模块进行通信;这种系统结构使得该系统的功能升级和扩展变得非常容易,接口电路的设计也很简单;基于该平台,开发人员只需将接口定义了解清楚,就可以进行VXI产品的开发设计,而不需要花费大量的时间和精力来学习CPU系统以及VXI总线;该设计方法已成功应用于产品开发,应用结果表明,该设计方法的引入极大地提高了VXI产品的开发效率。 相似文献