全文获取类型
| 收费全文 | 2881篇 |
| 免费 | 83篇 |
| 国内免费 | 85篇 |
专业分类
| 电工技术 | 105篇 |
| 综合类 | 98篇 |
| 化学工业 | 205篇 |
| 金属工艺 | 220篇 |
| 机械仪表 | 657篇 |
| 建筑科学 | 109篇 |
| 矿业工程 | 14篇 |
| 能源动力 | 119篇 |
| 轻工业 | 37篇 |
| 水利工程 | 12篇 |
| 石油天然气 | 21篇 |
| 武器工业 | 34篇 |
| 无线电 | 304篇 |
| 一般工业技术 | 383篇 |
| 冶金工业 | 33篇 |
| 原子能技术 | 7篇 |
| 自动化技术 | 691篇 |
出版年
| 2025年 | 16篇 |
| 2024年 | 30篇 |
| 2023年 | 55篇 |
| 2022年 | 70篇 |
| 2021年 | 108篇 |
| 2020年 | 66篇 |
| 2019年 | 70篇 |
| 2018年 | 55篇 |
| 2017年 | 93篇 |
| 2016年 | 84篇 |
| 2015年 | 83篇 |
| 2014年 | 135篇 |
| 2013年 | 164篇 |
| 2012年 | 146篇 |
| 2011年 | 216篇 |
| 2010年 | 151篇 |
| 2009年 | 174篇 |
| 2008年 | 118篇 |
| 2007年 | 144篇 |
| 2006年 | 148篇 |
| 2005年 | 119篇 |
| 2004年 | 104篇 |
| 2003年 | 78篇 |
| 2002年 | 87篇 |
| 2001年 | 71篇 |
| 2000年 | 62篇 |
| 1999年 | 77篇 |
| 1998年 | 80篇 |
| 1997年 | 44篇 |
| 1996年 | 56篇 |
| 1995年 | 40篇 |
| 1994年 | 25篇 |
| 1993年 | 15篇 |
| 1992年 | 11篇 |
| 1991年 | 8篇 |
| 1990年 | 8篇 |
| 1989年 | 7篇 |
| 1988年 | 3篇 |
| 1987年 | 1篇 |
| 1986年 | 4篇 |
| 1985年 | 7篇 |
| 1984年 | 4篇 |
| 1983年 | 3篇 |
| 1982年 | 6篇 |
| 1981年 | 1篇 |
| 1973年 | 2篇 |
排序方式： 共有3049条查询结果，搜索用时 15 毫秒
991.
We fabricated solution-processed flexible inverted organic solar cell (IOSC) modules (10 cm × 10 cm) on roll-to-roll (RTR) sputtered ITO/Ag/ITO multilayer cathodes. By using a pilot-scale RTR sputtering system equipped with mid-range frequency power for dual ITO targets and direct current power for the Ag target, we were able to continuously deposit a high-quality ITO/Ag/ITO multilayer on PET substrate with a width of 700 mm and length of 20,000 mm as a function of Ag thickness. At the Ag thickness of 12 nm, the ITO/Ag/ITO multilayer had a very low sheet resistance of 3.03 Ohm/square and high transmittance of 88.17%, which are better values than those of amorphous ITO film. A strip-type ITO/Ag/ITO cathode was successfully patterned using a RTR wet etching process. Successful operation of flexible IOSC modules on RTR sputtered ITO/Ag/ITO cathodes indicate that the RTR sputtering technique is a promising coating process for fabrication of high-quality transparent and flexible cathodes and can advance the commercialization of cost-efficient flexible IOSCs. 相似文献
992.
《低温学》2016
The transfer of liquid helium (LHe) into mobile dewars or transport vessels is a common and unavoidable process at LHe decant stations. During this transfer reasonable amounts of LHe evaporate due to heat leak and pressure drop. Thus generated helium gas needs to be collected and reliquefied which requires a huge amount of electrical energy. Therefore, the design of transfer lines used at LHe decant stations has been optimised to establish a LHe transfer with minor evaporation losses which increases the overall efficiency and capacity of LHe decant stations. This paper presents the experimental results achieved during the thermohydraulic optimisation of a flexible LHe transfer line. An extensive measurement campaign with a set of dedicated transfer lines equipped with pressure and temperature sensors led to unique experimental data of this specific transfer process. The experimental results cover the heat leak, the pressure drop, the transfer rate, the outlet quality, and the cool-down and warm-up behaviour of the examined transfer lines. Based on the obtained results the design of the considered flexible transfer line has been optimised, featuring reduced heat leak and pressure drop. 相似文献
993.
This article presents a novel and unifying method for routing of flexible one-dimensional components such as cables, hoses and pipes with geometric design constraints. A deterministic and resolution complete grid search is used to find a nominal configuration of the component that is collision-free and satisfies functional and manufacturing constraints. Local refinement is done in tandem with a computationally efficient and physically accurate simulation model based on Cosserat rod theory to ensure that the deformed configuration still satisfies functional constraints when influenced by gravity. Test results show that the method is able to solve industrial scenarios involving complex geometries and real constraints with different objectives in mere seconds. 相似文献
994.
《Displays》2016
A new method is developed for the preparation of a transparent electrically conductive hybrid polymer films which maintain their electrical conductivity when subjected to deformation in two and three dimensions including bending, stretching and twisting. These films are made by a hybrid roll to roll (R2R) process where electrically conductive nanofibers are partially embedded in solution cast dielectric polymer films such as poly(methyl methacrylate) (PMMA), polyimide (PI) or polyurethanes (PU). Nanofibers partially embedded in films can be laser ablated to obtain in-plane anisotropic electrical conductivity created in the form of parallel conductive lines separated by non-conductive spaces on the film surface. The patterned films can be used for high resolution pixel addressable liquid crystal displays. There are several situations, such as wearable sensors, curved displays and advanced flexible OLED lightings, where elastic extensibility and/or permanent deformability are desired without significant loss of electrical conductivity. To satisfy this demand, the multifunctional films can be made elastic, thermally deformable with the judicious choice of materials comprising the nanofibers and the matrix they are embedded in. The multifunctional transparent conductive films are easily manufactured through a low-cost continuous hybrid roll to roll process. Furthermore, they can be used in future displays, solar cells, wearable electronics and skin attached sensors requiring flexibility as well as stretchability and more desirably subsequent recovery after cessation of stress and strains without any loss of electrical conductivity. 相似文献
995.
This paper presents an electromagnetic conveyance system called electromagnetic modular Smart Surface (emSS) permitting to move pallets on a planar surface in a microfactory context. The proposed surface concept allows flexibility in reconfiguring the system layout along with product routing. The possibilities of accurate positioning of the moving pallet and controlling multiple pallets on the surface make the emSS suitable for reconfigurable and flexible manufacturing systems. However, the emSS control needs to be robust and scalable to adapt the changes in manufacturing systems. A framework is therefore defined to monitor and control the emSS by simulation or in-line. It allows to define product routing on the emSS by satisfying numerous requirements such as reduction in energy consumption, collision avoidance, etc., and to minimize the human interventions by changing product routing when emSS component failures occur. A first experiment realized on an emSS prototype, allowed to compare two paths strategies regarding cost function linked to energy consumption and velocities. Two other studies exploit the emSS modeling in terms of pallet path generation and simulation of collision avoidance. 相似文献
996.
The U.S. Naval shipbuilding industry faces significant challenges to build ships on-time and within budgeted cost. To achieve greater efficiency and timeliness in shipbuilding, we developed a flexible two-stage queueing model under a CONWIP job release policy to enhance the planning and control of the outfitting process, one of the key processes in shipbuilding. The model is formulated using Markov Decision Processes which can provide (1) the optimal dynamic control policy and (2) the optimal cost. The numerical results showed that the optimal control policy is a state dependent threshold type policy and very complex to analyze. Therefore, we developed a static model to simplify the dynamic model and used Mean Value Analysis to gain insights. Using both data from the dynamic model and the static model, we developed a regression model to calculate a threshold policy heuristic. Testing reveals that the performance of this heuristic is very close to the optimal. 相似文献
997.
This paper addresses the stable scheduling of multi-objective problem in flexible job shop scheduling with random machine breakdown. Recently, numerous studies are conducted about robust scheduling; however, implementing a scheme which prevents a tremendous change between scheduling and after machine breakdown (preschedule and realized schedule, respectively) can be critical for utilizing available resources. The stability of the schedule can be detected by a slight deviation of start and completion time of each job between preschedule and realized schedule under the uncertain conditions. In this paper, two evolutionary algorithms, NSGA-II and NRGA, are applied to combine the improvement of makespan and stability simultaneously. A simulation approach is used to evaluate the state and condition of the machine breakdowns. After the introduction of the evaluation criteria, the proposed algorithms are tested on a variety of benchmark problems. Finally, through performing statistical tests, the algorithm with higher performance in each criterion is identified. 相似文献
998.
《Ceramics International》2017,43(5):4536-4544
Al-doped zinc oxide (AZO) thin films were deposited onto flexible ultra-thin glass substrates by using a direct current (DC) magnetron sputtering process. The effects of sputtering power, working pressure and substrate temperature on the morphology and optoelectronic performances of AZO films were investigated. The optimal sputtering power, working pressure and substrate temperature for AZO film were determined to be 100 W, 0.9 Pa and 150 ℃, respectively. Further increasing or decreasing the sputtering power, working pressure and substrate temperature degrades the quality of AZO films. XRD patterns show all as-sputtered AZO thin films are preferred to grow along <0002> direction. Moreover, the largest grain size, which depicts the best microstructure of AZO films, matches with the smallest stress value. It can be seen from SEM images that the surface is smooth and dense. The smallest value of the resistivity is 1.784×10−3 Ω cm and the average transmittance of all AZO films in the visible range is about 80%. The X-ray photoelectron spectroscopy spectra show that the amount of Al element in the AZO film is very small. 相似文献
999.
《Ceramics International》2017,43(6):4803-4806
Recently, flexible nanogenerators have attracted much attention due to the continuous demand of portable electronic devices. Thus, in our present work, a flexible piezoelectric nanogenerator (pNG) was fabricated by mixing 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 nanoparticles (BCTZ NPs) and a PDMS polymer matrix. The flexible device exhibited excellent performance with maximum open-circuit voltage of 0.6 V and short-circuit current of 7.5 nA. BCTZ NPs were prepared by a reaction between a metallic salt and a metallic oxide in a solution of composite-hydroxide eutectic. XRD pattern showed BCTZ NPs to have pure perovskite structure. In this paper, the structure, morphology of the BCTZ NPs, and electric property of the BCTZ-based pNG were systematically studied. With the advantages of small-size, environmentally friendly, high flexibility, and high-sensitivity to external vibration, BCTZ will open up a range of new applications. 相似文献
1000.
The assembly of electronic components on printed circuit boards is performed in a line of automated placement machines, each equipped with a feeder unit that contains the component reels required for a product type. Assembling multiple product types by a single machine requires the replacement of certain components in the feeder unit. Increasingly, assembly machines are equipped with modular feeder units, enabling the replacement of a larger group of component reels. To minimize the machine setup time, component reel modules can be preassigned with the necessary component types, thus requiring only the loading of a suitable module set for each product. This work introduces and analyzes the problem of constructing the minimum number of component reel modules, with the objective that a set of jobs can be manufactured without individual component reel changes. We show that the problem is NP-hard and provide an integer programming formulation for it. We also introduce two heuristics based on job grouping, and analyze the results. 相似文献