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   8655篇
  免费   762篇
  国内免费   401篇
电工技术   492篇
综合类   686篇
化学工业   1354篇
金属工艺   490篇
机械仪表   571篇
建筑科学   703篇
矿业工程   217篇
能源动力   246篇
轻工业   731篇
水利工程   185篇
石油天然气   378篇
武器工业   67篇
无线电   957篇
一般工业技术   943篇
冶金工业   391篇
原子能技术   74篇
自动化技术   1333篇
  2024年   47篇
  2023年   159篇
  2022年   227篇
  2021年   369篇
  2020年   298篇
  2019年   215篇
  2018年   251篇
  2017年   265篇
  2016年   245篇
  2015年   331篇
  2014年   408篇
  2013年   500篇
  2012年   571篇
  2011年   592篇
  2010年   535篇
  2009年   508篇
  2008年   528篇
  2007年   417篇
  2006年   463篇
  2005年   381篇
  2004年   300篇
  2003年   364篇
  2002年   359篇
  2001年   312篇
  2000年   191篇
  1999年   223篇
  1998年   140篇
  1997年   129篇
  1996年   110篇
  1995年   86篇
  1994年   79篇
  1993年   51篇
  1992年   47篇
  1991年   31篇
  1990年   25篇
  1989年   17篇
  1988年   14篇
  1987年   7篇
  1986年   6篇
  1985年   6篇
  1984年   4篇
  1981年   4篇
  1980年   2篇
  1959年   1篇
排序方式: 共有9818条查询结果,搜索用时 15 毫秒
101.
以词汇主义形式语法为基础,建立了链接文法与合一理论相结合的句法分析新方法.在封闭测试中,基于合一的链接文法句法分析精确率和召回率相比传统链接文法分别提高了9.6%和14.1%.实验表明方法具有一定独创性和高效性.  相似文献   
102.
Chemotherapy-induced enteritis is one of the side effects associated with cancer therapy, which significantly affects the treatment effect, but there is no effective clinical detection method that can early diagnose its occurrence and progression. Here, a series of second near-infrared window (NIR-II) hybrid nanosensors are designed that consisted of lanthanide nanoparticles and β-Mo2C-derived polymetallic oxomolybdate nanoclusters (Ln@POM). Based on the high sensitivity of POM to reactive oxygen species (ROS) closely related to chemotherapy-induced enteritis, the NIR-II luminescence intensity and lifetime of Ln@POM (Ln: Yb3+, Nd3+, Ho3+, Tm3+, Er3+) show excellent responsiveness to H2O2 and HClO with the detection limit down to 0.15 and 0.14 µm , respectively. Utilizing Nd@POM as a ROS-activated NIR-II nanosensor, the chemotherapeutic enteritis is successfully detected within 7 h after induction of chemotherapy drugs, which is significantly earlier than the gold standard method (immunohistochemistry, 24 h). These results demonstrate that the designed hybrid nanosensors are promising optical tools for the early diagnosis of ROS-related diseases.  相似文献   
103.
Liquid crystalline polymers (LCPs), especially liquid crystalline elastomers (LCEs) can generate ultrahigh shape change amplitude but has lower mechanical strength. Although some attempts have been tried to improve the mechanical performance of LCE, there are still limitations including complicated fabrication and high actuation temperature. Here, a versatile method is reported to fabricate light-driven actuator by covalently cross-linking polyurethane (PU) into LCP networks (PULCN). This new scheme is distinct from the previous interpenetrating network strategy, the hydrogen bonds and covalent bonds are used in this study to improve the miscibility of non-liquid-crystalline PU and LCP materials and enhance the stability of the composite system. This material not only possesses the shape memory properties of PU but shows shape-changing behavior of LCPs. With a shrinkage ratio of 20% at the phase transition temperature, the prepared materials reached a maximum mechanical strength of 20 MPa, higher than conventional LCP. Meanwhile, the resulting film shows diverse and programmable initial shapes by constructing crosslinking density gradient across the thickness of the film. By integration of PULCN with near-infrared light-responsive polydopamine, local and sequential light control is achieved. This study may provide a new route for the fabrication of programmable and mechanically robust light-driven soft actuator.  相似文献   
104.
Ferromagnetic materials with a strong spin-orbit coupling (SOC) have attracted much attention in recent years because of their exotic properties and potential applications in energy-efficient spintronics. However, such materials are scarce in nature. Here, a proximity-induced paramagnetic to ferromagnetic transition for the heavy transition metal oxide CaRuO3 in (001)-(LaMnO3/CaRuO3) superlattices is reported. Anomalous Hall effect is observed in the temperature range up to 180 K. Maximal anomalous Hall conductivity and anomalous Hall angle are as large as ∼15 Ω−1 cm−1 and ∼0.93%, respectively, by one to two orders of magnitude larger than those of the typical 3d ferromagnetic oxides such as La0.67Sr0.33MnO3. Density functional theory calculations indicate the existence of avoid band crossings in the electronic band structure of the ferromagnetic CRO layer, which enhances Berry curvature thus strong anomalous Hall effects. Further evidences from polarized neutron reflectometry show that the CaRuO3 layers are in a fully ferromagnetic state (∼0.8 μB/Ru), in sharp contrast to the proximity-induced canted antiferromagnetic state in 5d oxides SrIrO3 and CaIrO3 (∼0.1 μB/Ir). More than that, the magnetic anisotropy of the (001)-(LaMnO3/CaRuO3) superlattices is eightfold symmetric, showing potential applications in the technology of multistate data storage.  相似文献   
105.
A polarization modulated directional backlight autostereoscopic display is proposed and demonstrated. The system consists of the orthogonally polarized backlight, the Fresnel lens array, a light shaping diffuser film, and a liquid crystal display (LCD) with a microphase retardation film. The autostereoscopic image pair carried by the directional light with different polarization directions is simultaneously projected to different spatial directions. The simulation and experimental results show that the directional projection of parallax images is realized for a high-quality autostereoscopic display with large viewing angle and continuous viewing volume, hence making it suitable for practical applications.  相似文献   
106.
Metalenses are two-dimensional planar metamaterial lenses, which have the advantages of high efficiency and easy integration. Based on the method of spatial multiplexing, a metalens with a wide working waveband is designed by arranging TiO2 nanopillars under the resonance phase regulation. In addition, choosing an assistant metalens with optimized heights is effective to enhance metalens’s focusing, which is also illustrated in this paper. The metalens, designed with numerical aperture (NA) of 0.72 and center working wavelength of 600 nm, achieves the working waveband of 550—660 nm, the focus point’s size of below 420 nm, and the focusing efficiency of more than 30%.  相似文献   
107.
With the rapid development of mobile devices and deep learning, mobile smart applications using deep learning technology have sprung up. It satisfies multiple needs of users, network operators and service providers, and rapidly becomes a main research focus. In recent years, deep learning has achieved tremendous success in image processing, natural language processing, language analysis and other research fields. Despite the task performance has been greatly improved, the resources required to run these models have increased significantly. This poses a major challenge for deploying such applications on resource-restricted mobile devices. Mobile intelligence needs faster mobile processors, more storage space, smaller but more accurate models, and even the assistance of other network nodes. To help the readers establish a global concept of the entire research direction concisely, we classify the latest works in this field into two categories, which are local optimization on mobile devices and distributed optimization based on the computational position of machine learning tasks. We also list a few typical scenarios to make readers realize the importance and indispensability of mobile deep learning applications. Finally, we conjecture what the future may hold for deploying deep learning applications on mobile devices research, which may help to stimulate new ideas.  相似文献   
108.
Liang  Likeng  Hao  Tianyong  Zhan  Choujun  Qiu  Hong  Wang  Fu Lee  Yan  Jun  Weng  Heng  Qu  Yingying 《Neural computing & applications》2022,34(19):16311-16324
Neural Computing and Applications - Medical concept normalization aims to construct a semantic mapping between mentions and concepts and to uniformly represent mentions that belong to the same...  相似文献   
109.
Zhan  Baoqiang  Zhang  Shu  Du  Helen S.  Yang  Xiaoguang 《Computational Economics》2022,60(3):861-882
Computational Economics - Arbitrage opportunity exploration is important to ensure the profitability of statistical arbitrage. Prior studies that concentrate on cointegration model and other...  相似文献   
110.
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