首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   13550篇
  免费   1060篇
  国内免费   559篇
电工技术   717篇
技术理论   1篇
综合类   910篇
化学工业   2503篇
金属工艺   693篇
机械仪表   848篇
建筑科学   909篇
矿业工程   373篇
能源动力   387篇
轻工业   957篇
水利工程   241篇
石油天然气   672篇
武器工业   92篇
无线电   1504篇
一般工业技术   1853篇
冶金工业   628篇
原子能技术   159篇
自动化技术   1722篇
  2024年   59篇
  2023年   238篇
  2022年   335篇
  2021年   516篇
  2020年   433篇
  2019年   340篇
  2018年   404篇
  2017年   449篇
  2016年   370篇
  2015年   509篇
  2014年   645篇
  2013年   821篇
  2012年   782篇
  2011年   787篇
  2010年   771篇
  2009年   693篇
  2008年   653篇
  2007年   708篇
  2006年   708篇
  2005年   581篇
  2004年   412篇
  2003年   459篇
  2002年   536篇
  2001年   429篇
  2000年   356篇
  1999年   369篇
  1998年   321篇
  1997年   283篇
  1996年   246篇
  1995年   193篇
  1994年   165篇
  1993年   113篇
  1992年   100篇
  1991年   82篇
  1990年   63篇
  1989年   48篇
  1988年   41篇
  1987年   24篇
  1986年   31篇
  1985年   10篇
  1984年   16篇
  1983年   9篇
  1982年   9篇
  1981年   11篇
  1980年   13篇
  1979年   6篇
  1978年   3篇
  1977年   3篇
  1976年   8篇
  1959年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
分析了GB/T20109-2006所述全新风除湿机节能的5个方面:1)冷凝热回收.2)室内回风热回收.3)冷凝水冷回收.4)处理后新风冷回收.5)新风热回收.通过对典型案例做深入探讨发现:采用板翅式热回收器或热管换热器对新风处理后新风进行冷回收预冷新风,能够降低制冷系统冷负荷20%~30%,显著提高全新风除湿机的单位输入功率除湿量.  相似文献   
102.
A successful design for a UWB (ultra-wideband antennas) antenna based on NRD-guide (nonradiative dielectric waveguide) with small side-leakage is presented. The rule of the theoretical selection of its parameters, if NRD-guide is used as the UWB antennas, is studied firstly, then the temporal propagation characteristics of the NRD-guide and the radiation characteristics for an tapered open-ended NRD-guide are calculated by FDTD (finite-difference time-domain) method.  相似文献   
103.
Traditionally, we use a slab to mimic a surface and we constrain the slab to have the bulk-terminated 2D lattice constants. Here we propose a different model in which we impose no constraints, allowing all coordinates including the 2D slab itself to relax. We perform DFT calculations on both models. We find that the unconstrained slabs yield better agreement with experimental results and they have lower total energies. The optimized 2D lattice constants of the unconstrained slabs eventually converge to the attached bulk value. The total energy difference reveals that, with odd number trilayers, the unconstrained slab is much closer to the corresponding constrained slab. The surface energies both converge to the individual values with the number of atomic layers.  相似文献   
104.
万璐  刘阳 《电子科技》2007,(1):17-19
无线信道在实际中难以测试,但信道仿真可以解决这一问题。文中给出了一种灵活且适应性强的无线移动信道模型,并给出了该模型中的衰落信道模型及算法,运用该算法对衰落信道进行仿真,给出衰落信号的仿真结果以及输入信号经衰落信道处理后的结果。  相似文献   
105.
针对内核态驱动开销大,而用户态驱动可以消除系统调用及数据包拷贝等高额开销的特点,文章将一个内核态的网卡驱动程序移植到了用户态。文章分析了内核态驱动与用户态驱动的软件框架特点,给出了移植用户态驱动需要解决的问题及相应的技术方案,并给出了移植实现的要点及性能优化措施。实验表明,经移植和优化的用户态驱动程序可以达到10Gbps的数据包输入/输出速度,从而可以应用于各种高速流量监视系统中。  相似文献   
106.
万芳 《电子质量》2012,(5):36-39
该文阐述了电压、功率、电压电平、功率电平的基本概念和它们之间的互换及其应用。  相似文献   
107.
Tendon–bone interface is prevalent in the human body. It is divided into four zones: tendon (soft tissue), unmineralized fibrocartilage, mineralized fibrocartilage, and bone (hard tissue). Tendon–bone interface is characterized by a cell phenotype gradient that appears in the different zones. The cell phenotype gradients at the tendon–bone interface are orchestrated by specific intracellular molecular mechanisms, extracellular factors, immune signals, and neurovascular factors. These features have inspired scientists to design systems that mimic natural cell phenotype gradients. These biomimetic systems include the construction of cell sheets, regulation of cellular microenvironments, and the design of gradient functional scaffolds. Exploration of methods to mimic cell phenotype gradients is instructional for future clinical applications in reconstituting the tendon–bone interface. The present review elucidates the gradient composition of the tendon–bone interface. The associated regulatory mechanisms and applications are discussed, with the anticipation of creating a mise en scène for future research in interface tissue engineering.  相似文献   
108.
The practicality of aqueous zinc ion batteries (AZIBs) for large-scale energy storage is hindered by challenges associated with zinc anodes. In this study, a low-cost and multi-function electrolyte additive, cetyltrimethyl ammonium bromide (CTAB), is presented to address these issues. CTAB adsorbs onto the zinc anode surface, regulating Zn2+ deposition orientation and inhibiting dendrite formation. It also modifies the solvation structure of Zn2+ to reduce water reactivity and minimize side reactions. Additionally, CTAB optimizes key physicochemical parameters of the electrolyte, enhancing the stability of the electrode/electrolyte interface and promoting reversibility in AZIBs. Theoretical simulations combined with operando synchrotron radiation-based in situ Fourier transform infrared spectra and in situ electrochemical impedance spectra further confirm the modified Zn2+ coordination environment and the adsorption effect of CTAB cations at the anode/electrolyte interface. As a result, the assembled Zn-MnO2 battery demonstrates a remarkable specific capacity of 126.56 mAh g−1 at a high current density of 4 A g−1 after 1000 cycles. This work highlights the potential of CTAB as a promising solution for improving the performance and practicality of AZIBs for large-scale energy storage applications.  相似文献   
109.
Conductive polymer/sulfur composite materials were prepared by heating the mixture of polyacrylonitrile (PAN) and sublimed sulfur. During the heating process, PAN was dehydrogenated by sulfur, forming a conductive main chain similar to polyacetylene. At the same time, the high‐polarity functional group –CN cyclized at the melt state, forming a thermally stable heterocyclic compound in which sulfur was embedded. The nanodispersed composites showed excellent electrochemical properties. Tested as cathode material in a non‐aqueous lithium cell based on poly(vinylidene fluoride) (PVDF) gel electrolyte at room temperature, the composite exhibited a specific capacity up to 850 mA h g–1 in the initial cycle. Its specific capacity remained above 600 mA h g–1 after 50 cycles, about five times that of LiCoO2, and recovered partly after replacement of the anode with a fresh lithium sheet. The utilization of the electrochemically active sulfur was about 90 % assuming a complete reaction to the product, Li2S.  相似文献   
110.
刘翠香 《电子质量》2005,(3):6-7,12
介绍了GPIB通用接口母线的特点及其优势,将其应用于单片机USB-GPIB框架的数据传输系统,其中USB部分Cypress公司基于2.0协议的CY68013控制芯片,GPIB协议部分采用NI公司的NAT9914控制芯片。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号