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   4742篇
  免费   353篇
  国内免费   13篇
电工技术   52篇
综合类   4篇
化学工业   1213篇
金属工艺   204篇
机械仪表   323篇
建筑科学   70篇
矿业工程   3篇
能源动力   228篇
轻工业   432篇
水利工程   13篇
石油天然气   10篇
武器工业   2篇
无线电   775篇
一般工业技术   1046篇
冶金工业   206篇
原子能技术   47篇
自动化技术   480篇
  2024年   7篇
  2023年   81篇
  2022年   118篇
  2021年   188篇
  2020年   134篇
  2019年   158篇
  2018年   183篇
  2017年   168篇
  2016年   197篇
  2015年   138篇
  2014年   208篇
  2013年   287篇
  2012年   347篇
  2011年   422篇
  2010年   292篇
  2009年   278篇
  2008年   237篇
  2007年   197篇
  2006年   175篇
  2005年   136篇
  2004年   139篇
  2003年   117篇
  2002年   117篇
  2001年   104篇
  2000年   96篇
  1999年   81篇
  1998年   93篇
  1997年   56篇
  1996年   64篇
  1995年   48篇
  1994年   21篇
  1993年   32篇
  1992年   25篇
  1991年   13篇
  1990年   14篇
  1989年   12篇
  1988年   14篇
  1987年   14篇
  1986年   13篇
  1985年   16篇
  1984年   12篇
  1983年   3篇
  1982年   5篇
  1981年   7篇
  1980年   7篇
  1979年   4篇
  1978年   3篇
  1977年   7篇
  1976年   12篇
  1967年   2篇
排序方式: 共有5108条查询结果,搜索用时 15 毫秒
31.
Abstract— A touch‐screen‐panel (TSP) embedded 12.1‐in. LCD employing a standard existing a‐Si:H TFT‐LCD process has been successfully developed. Compared with conventional external touch‐screen panels, which use additional components to detect touch events, the new internal TSP exhibits a clearer image and improved touch feeling, as well as increased sensing speed using discrete sensing lines to enable higher‐speed sensing functions including handwriting. The new internal digital switching TSP can be fabricated with low cost because it does not require any additional process steps compared to a standard a‐Si:H TFT‐LCD.  相似文献   
32.
Abstract— A flexible fluorescent lamp that utilizes the same plasma discharge mode as in PDPs has been manufactured. The structure of the flexible lamp is simple and easy to manufacture. All‐plastic materials including plastic substrates, barrier ribs (spacers), and sealants for low‐temperature manufacturing processing have been adopted except for the phosphor and MgO thin film. The MgO thin films were coated on the plastic substrates as a protection layer against the plasma discharge. The adhesion and biaxial texture of MgO thin film deposited on the plastic substrates, poly‐ethyle‐nenaphthalate (PEN) and polycarbonate (PC), at low temperature (100–180°C) has been characterized. The MgO film on PEN shows good adhesion under a repeated bending test. The manufactured flexible lamp consists of two plastic substrates of about 3 in. on the diagonal, barrier rib (spacer), and external ITO electrodes. The Ne‐Xe (5%) gas mixture at 100–200 Torr was used for the discharge gas. A maximum surface luminance of about 100 cd/m2 was achieved for a 1 ‐kHz AC pulse.  相似文献   
33.
In a highly competitive market, customers' product affection is a critical factor to product success. However, understanding customers' affective needs is difficult to grasp; product design practitioners often misunderstand what customers really want. In this study we report our experience in developing and using an affective design framework that identified critical affective features customers have on products and are systematically incorporated into product design attributes. To identify key affective features such as luxuriousness, we utilized the Kansei engineering methodology. This approach consists of three steps: (1) selecting related affective features and product design attributes through a comprehensive literature survey, expert panel opinion, and focus group interviews; (2) conducting evaluation experiments; and (3) developing Kansei models using multivariate statistical analysis and analyzing critical product design attributes. To demonstrate applicability of the proposed affective design framework, 30 customers and 30 product design practitioners participated in an evaluation experiment for car crash pads, and 44 customers and 20 designers participated in an evaluation experiment for two interior room products (wallpapers and flooring materials). The evaluation experiments were conducted via systematically developed questionnaires consisting of a 7‐point semantic differential scale and a 100‐point magnitude estimation scale. The results of the experiments were analyzed using principal component regression and quantification theory type I method. Using the analyzed survey data, the relationship between luxuriousness and related affective features and product design attributes were identified. This relationship indicated that there was a significant difference in the perception of luxuriousness between customers and designers. Consequently, it is expected that the results of this study could provide a foundation for developing affective products. © 2009 Wiley Periodicals, Inc.  相似文献   
34.
Probabilistic structural design deals with uncertainties in response (e.g. stresses) and capacity (e.g. failure stresses). The calculation of the structural response is typically expensive (e.g., finite element simulations), while the capacity is usually available from tests. Furthermore, the random variables that influence response and capacity are often disjoint. In previous work we have shown that this disjoint property can be used to reduce the cost of obtaining the probability of failure via Monte Carlo simulations. In this paper we propose to use this property for an approximate probabilistic optimization based on exact capacity and approximate response distributions (ECARD). In Approximate Probabilistic Optimization Using ECARD, the change in response distribution is approximated as the structure is re-designed while the capacity distribution is kept exact, thus significantly reducing the number of expensive response simulations. ECARD may be viewed as an extension of SORA (Sequential Optimization and Reliability Assessment), which proceeds with deterministic optimization iterations. In contrast, ECARD has probabilistic optimization iterations, but in each iteration, the response distribution is approximated so as not to require additional response calculations. The use of inexpensive probabilistic optimization allows easy incorporation of system reliability constraints and optimal allocation of risk between failure modes. The method is demonstrated using a beam problem and a ten-bar truss problem. The former allocates risk between two different failure modes, while the latter allocates risk between members. It is shown that ECARD provides most of the improvement from risk re-allocation that can be obtained from full probabilistic optimization.  相似文献   
35.
Reversible metal-filamentary mechanism has been widely investigated to design an analog resistive switching memory (RSM) for neuromorphic hardware-implementation. However, uncontrollable filament-formation, inducing its reliability issues, has been a fundamental challenge. Here, an analog RSM with 3D ion transport channels that can provide unprecedentedly high reliability and robustness is demonstrated. This architecture is realized by a laser-assisted photo-thermochemical process, compatible with the back-end-of-line process and even applicable to a flexible format. These superior characteristics also lead to the proposal of a practical adaptive learning rule for hardware neural networks that can significantly simplify the voltage pulse application methodology even with high computing accuracy. A neural network, which can perform the biological tissue classification task using the ultrasound signals, is designed, and the simulation results confirm that this practical adaptive learning rule is efficient enough to classify these weak and complicated signals with high accuracy (97%). Furthermore, the proposed RSM can work as a diffusive-memristor at the opposite voltage polarity, exhibiting extremely stable threshold switching characteristics. In this mode, several crucial operations in biological nervous systems, such as Ca2+ dynamics and nonlinear integrate-and-fire functions of neurons, are successfully emulated. This reconfigurability is also exceedingly beneficial for decreasing the complexity of systems—requiring both drift- and diffusive-memristors.  相似文献   
36.
Development of multifunctional electrocatalysts with high efficiency and stability is of great interest in recent energy conversion technologies. Herein, a novel heteroelectrocatalyst of molecular iron complex (FeMC)-carbide MXene (Mo2TiC2Tx) uniformly embedded in a 3D graphene-based hierarchical network (GrH) is rationally designed. The coexistence of FeMC and MXene with their unique interactions triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy for excellent trifunctional catalytic activities. Meanwhile, the highly porous GrH effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Therefore, the FeMC–MXene/GrH results in superb performances towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The practical tests indicate that Zn/Al–air batteries derived from FeMC–MXene/GrH cathodic electrodes produce high power densities of 165.6 and 172.7 mW cm−2, respectively. Impressively, the liquid-state Zn–air battery delivers excellent cycling stability of over 1100 h. In addition, the alkaline water electrolyzer induces a low cell voltage of 1.55 V at 10 mA cm−2 and 1.86 V at 0.4 A cm−2 in 30 wt.% KOH at 80 °C, surpassing recent reports. The achievements suggest an exciting multifunctional electrocatalyst for electrochemical energy applications.  相似文献   
37.
The conventional hospital environment is transformed into digital transformation that focuses on patient centric remote approach through advanced technologies. Early diagnosis of many diseases will improve the patient life. The cost of health care systems is reduced due to the use of advanced technologies such as Internet of Things (IoT), Wireless Sensor Networks (WSN), Embedded systems, Deep learning approaches and Optimization and aggregation methods. The data generated through these technologies will demand the bandwidth, data rate, latency of the network. In this proposed work, efficient discrete grey wolf optimization (DGWO) based data aggregation scheme using Elliptic curve Elgamal with Message Authentication code (ECEMAC) has been used to aggregate the parameters generated from the wearable sensor devices of the patient. The nodes that are far away from edge node will forward the data to its neighbor cluster head using DGWO. Aggregation scheme will reduce the number of transmissions over the network. The aggregated data are preprocessed at edge node to remove the noise for better diagnosis. Edge node will reduce the overhead of cloud server. The aggregated data are forward to cloud server for central storage and diagnosis. This proposed smart diagnosis will reduce the transmission cost through aggregation scheme which will reduce the energy of the system. Energy cost for proposed system for 300 nodes is 0.34μJ. Various energy cost of existing approaches such as secure privacy preserving data aggregation scheme (SPPDA), concealed data aggregation scheme for multiple application (CDAMA) and secure aggregation scheme (ASAS) are 1.3 μJ, 0.81 μJ and 0.51 μJ respectively. The optimization approaches and encryption method will ensure the data privacy.  相似文献   
38.
A solid-state drawing and winding process was done to create thin aligned carbon nanotube (CNT) sheets from CNT arrays. However, waviness and poor packing of CNTs in the sheets are two main weaknesses restricting their reinforcing efficiency in composites. This report proposes a simple press-drawing technique to reduce wavy CNTs and to enhance dense packing of CNTs in the sheets. Non-pressed and pressed CNT/epoxy composites were developed using prepreg processing with a vacuum-assisted system. Effects of pressing on the mechanical properties of the aligned CNT sheets and CNT/epoxy composites were examined. Pressing with distributed loads of 147, 221, and 294 N/m showed a substantial increase in the tensile strength and the elastic modulus of the aligned CNT sheets and their composites. The CNT sheets under a press load of 221 N/m exhibited the best mechanical properties found in this study. With a press load of 221 N/m, the pressed CNT sheet and its composite, respectively, enhanced the tensile strength by 139.1 and 141.9%, and the elastic modulus by 489 and 77.6% when compared with non-pressed ones. The pressed CNT/epoxy composites achieved high tensile strength (526.2 MPa) and elastic modulus (100.2 GPa). Results show that press-drawing is an important step to produce superior CNT sheets for development of high-performance CNT composites.  相似文献   
39.
The silver‐embedded gelatin (AgG) thin film produced by the solution method of metal salts dissolved in gelatin is presented. Its simple fabrication method ensures the uniform distribution of Ag dots. Memory devices based on AgG exhibit good device performance, such as the ON/OFF ratio in excess of 105 and the coefficient of variation in less of 50%. To further investigate the position of filament formation and the role of each element, current sensing atomic force microscopy (CSAFM) analysis as well as elemental line profiles across the two different conditions in the LRS and HRS are analyzed. The conductive and nonconductive regions in the current map of the CSAFM image show that the conductive filaments occur in the AgG layer around Ag dots. The migration of oxygen ions and the redox reaction of carbon are demonstrated to be the driving mechanism for the resistive switching of AgG memory devices. The results show that dissolving metal salts in gelatin is an effective way to achieve high‐performance organic–electronic applications.  相似文献   
40.
Diamond films 60 and 170 µm in thickness were grown by PACVD (plasma-assisted chemical vapor deposition) under similar conditions. The thermal diffusivity of these freestanding films was measured between 100 and 300 K using AC calorimetry. Radiation heat loss from the surface was estimated by analyzing both the amplitude and the phase shift of a lock-in amplifier signal. Thermal conductivity was calculated using the specific heat data of natural diamond. At room temperature, the thermal conductivity of the 60 and 170 m films is 9 and 16 W-cm–1. K–1 respectively, which is 40–70% that of natural diamond, The temperature dependence of thermal conductivity of the CVD diamond films is similar to that of natural diamond, Phonon scattering processes are considered using the Debye model, The microsize of the grain boundary has a significant effect on the mean free path of phonons at low temperatures. The grain in CVD diamond film is grown as a columnar structure, Thus, the thicker film has the larger mean grain size and the higher thermal conductivity. Scanning electron microscopy (SEM) and Raman spectroscopy were used to study the microstructure of the CVD diamond films. In this experiment, we evaluated the quality of CVD diamond film of the whole sample by measuring the thermal conductivity.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.  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