全文获取类型
收费全文 | 11200篇 |
免费 | 2218篇 |
国内免费 | 567篇 |
专业分类
电工技术 | 1689篇 |
技术理论 | 1篇 |
综合类 | 934篇 |
化学工业 | 813篇 |
金属工艺 | 300篇 |
机械仪表 | 1293篇 |
建筑科学 | 550篇 |
矿业工程 | 232篇 |
能源动力 | 208篇 |
轻工业 | 311篇 |
水利工程 | 140篇 |
石油天然气 | 194篇 |
武器工业 | 117篇 |
无线电 | 2664篇 |
一般工业技术 | 2834篇 |
冶金工业 | 148篇 |
原子能技术 | 80篇 |
自动化技术 | 1477篇 |
出版年
2024年 | 85篇 |
2023年 | 411篇 |
2022年 | 351篇 |
2021年 | 551篇 |
2020年 | 638篇 |
2019年 | 567篇 |
2018年 | 550篇 |
2017年 | 590篇 |
2016年 | 609篇 |
2015年 | 615篇 |
2014年 | 801篇 |
2013年 | 711篇 |
2012年 | 770篇 |
2011年 | 817篇 |
2010年 | 614篇 |
2009年 | 648篇 |
2008年 | 595篇 |
2007年 | 645篇 |
2006年 | 660篇 |
2005年 | 550篇 |
2004年 | 425篇 |
2003年 | 325篇 |
2002年 | 247篇 |
2001年 | 214篇 |
2000年 | 168篇 |
1999年 | 151篇 |
1998年 | 125篇 |
1997年 | 108篇 |
1996年 | 83篇 |
1995年 | 76篇 |
1994年 | 65篇 |
1993年 | 41篇 |
1992年 | 46篇 |
1991年 | 29篇 |
1990年 | 32篇 |
1989年 | 25篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1959年 | 1篇 |
1955年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 612 毫秒
1.
针对常见泥石流防治结构被冲击破坏的问题,基于“柔性消能”理念,结合张弦梁结构和竖向预应力锚杆技术,提出一种既能改善结构受力性能、增加结构整体抗冲击能力、保证结构安全可靠,又能减小结构构件截面尺寸、节约成本、便于现场施工组装和后期运营维护的新型地锚张弦梁式泥石流格栅坝,并阐述其技术原理。根据泥石流荷载分布和新型地锚张弦梁式泥石流格栅坝的受力特征,给出其简化的内力计算方法;并利用SAP2000建立新结构有限元模型,分析了结构的整体受力,验证了构件简化计算方法的合理性;结合Python语言和Qt De? signer软件开发了相应的设计计算软件,对新型地锚张弦梁式泥石流格栅坝的内力进行求解。结果表明:提出的新结构抗冲击性能好,构件受力均匀;以后设计中应关注竖杆的剪切脆性破坏和立柱偏心受力情况,保证结构安全;变形协调仅使底层张弦梁与竖杆内力偏大,实际工程应用时,应着重验算底层构件,防止其破坏;文中提出的简化计算方法能较准确的反映结构的受力特性,具有一定的合理性,研究可为新型地锚张弦梁式泥石流格栅坝的设计计算和推广应用提供理论依据和技术支持。 相似文献
2.
Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films are attracting famous applications in antistatic coating, energy storage and conversion, printed electronics, and biomedical fields due to their conductivity, optical transparency and flexibility. However, PEDOT:PSS has poor dispersion stability during long-term storage and transport. Moreover, the dried PEDOT:PSS films are insoluble in any solvent and cannot be redispersed again. In comparison to bake drying, here, a feasible strategy to achieve mechanically redispersed PEDOT:PSS with the help of freeze-drying process was reported. The redispersed PEDOT:PSS can recover not only the initial characters such as pH, chemical composition, viscosity, and particle size under similar solid contents, but also conductivity and surface morphology of treated films. In addition, the treated film exhibits self-healing properties similar to pristine film in terms of mechanical and electrical properties. This technology enables reuse and overcomes the technical problems of PEDOT:PSS dispersion, realizing real-time processing to meet variable applications. 相似文献
3.
Zenan Yu Julian Moore Jean Calderon Lei Zhai Jayan Thomas 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(39):5289-5295
Cable‐shaped supercapacitors (SCs) have recently aroused significant attention due to their attractive properties such as small size, lightweight, and bendability. Current cable‐shaped SCs have symmetric device configuration. However, if an asymmetric design is used in cable‐shaped supercapacitors, they would become more attractive due to broader cell operation voltages, which results in higher energy densities. Here, a novel coil‐type asymmetric supercapacitor electrical cable (CASEC) is reported with enhanced cell operation voltage and extraordinary mechanical‐electrochemical stability. The CASECs show excellent charge–discharge profiles, extraordinary rate capability (95.4%), high energy density (0.85 mWh cm−3), remarkable flexibility and bendability, and superior bending cycle stability (≈93.0% after 4000 cycles at different bending states). In addition, the CASECs not only exhibit the capability to store energy but also to transmit electricity simultaneously and independently. The integrated electrical conduction and storage capability of CASECS offer many potential applications in solar energy storage and electronic gadgets. 相似文献
4.
The top illuminated organic photodetectors (OPDs) with a Dielectric/Metal/Dielectric (DMD) transparent anode are fabricated. The transparent electrode is composed of molybdenum trioxide (MoO3)/silver (Ag)/MoO3 layers and zinc oxide (ZnO)/aluminum (Al) is used for bottom cathode. The optimized DMD electrode has an optical transmittance of 85.7% at the wavelength of 546 nm and sheet resistance of ∼6 Ω/sq. The fabricated OPDs exhibit a high detectivity and wide range linearity. 相似文献
5.
Adaptive robust boundary control of shaft vibrations under perturbations with unknown upper bounds 下载免费PDF全文
This paper presents robust and adaptive boundary control designs to stabilize the two‐dimensional vibration of hybrid shaft model. The hybrid shaft is mathematically represented by a set of partial differential equations, governing the shaft vibrations, coupled to ordinary differential equations, describing rigid body spinning and dynamic boundary conditions. The control objective is to stabilize the transverse vibrations of the perturbed shaft while regulating the spinning rate. To achieve this, the paper first establishes robust boundary control laws that fulfil the control objective in the presence of modeling uncertainties and external disturbances operating over the shaft domain and boundary. Lyapunov‐based analyses show that the proposed robust control exponentially stabilizes the shaft with vanishing distributive perturbations, while assuring ultimately bounded vibrations in the case of nonvanishing perturbations. Then, adaptive control philosophy is utilized to achieve redesigned robust controllers that only use online adaptation of control gains without acquiring the knowledge of bounds on perturbations, as well as dynamic parameters. An advantage of this design is avoiding an overconservative robust control law, which may induce poor stability and chattering in tackling system perturbations with unknown upper bounds. Simulations through finite element method illustrate the results. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
7.
James E. Tyrrell Martyn G. Boutelle Alasdair J. Campbell 《Advanced functional materials》2021,31(1):2007086
Biological environments use ions in charge transport for information transmission. The properties of mixed electronic and ionic conductivity in organic materials make them ideal candidates to transduce physiological information into electronically processable signals. A device proven to be highly successful in measuring such information is the organic electrochemical transistor (OECT). Previous electrophysiological measurements performed using OECTs show superior signal-to-noise ratios than electrodes at low frequencies. Subsequent development has significantly improved critical performance parameters such as transconductance and response time. Here, interdigitated-electrode OECTs are fabricated on flexible substrates, with one such state-of-the-art device achieving a peak transconductance of 139 mS with a 138 µs response time. The devices are implemented into an array with interconnects suitable for micro-electrocorticographic application and eight architecture variations are compared. The two best-performing arrays are subject to the full electrophysiological spectrum using prerecorded signals. With frequency filtering, kHz-scale frequencies with 10 µV-scale voltages are resolved. This is supported by a novel quantification of the noise, which compares the gate voltage input and drain current output. These results demonstrate that high-performance OECTs can resolve the full electrophysiological spectrum and suggest that superior signal-to-noise ratios could be achieved in high frequency measurements of multiunit activity. 相似文献
8.
目前需求预测在整个印制电路板产业的生产活动控制中正扮演着越来越重要的角色。分析了影响印制电路板需求的因素和现有的预测方法,提出了一种适用于PCB产业需求预测的有效方法——遗传/BP—神经网络。实验表明该方法能够进一步改善印制电路板预测的准确度和减少生产成本的消耗。 相似文献
9.
10.
对微波陶瓷基印制板的制造工艺流程进行了简单的介绍,对所采用的工艺技术的有效性进行了较为详细的论述。 相似文献