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   98332篇
  免费   8404篇
  国内免费   3988篇
电工技术   6327篇
技术理论   3篇
综合类   6917篇
化学工业   14940篇
金属工艺   6207篇
机械仪表   8127篇
建筑科学   8393篇
矿业工程   4607篇
能源动力   2958篇
轻工业   8563篇
水利工程   2759篇
石油天然气   7707篇
武器工业   652篇
无线电   8505篇
一般工业技术   7223篇
冶金工业   4036篇
原子能技术   929篇
自动化技术   11871篇
  2025年   4篇
  2024年   1054篇
  2023年   1493篇
  2022年   2533篇
  2021年   3401篇
  2020年   2842篇
  2019年   2281篇
  2018年   2217篇
  2017年   2427篇
  2016年   2071篇
  2015年   2971篇
  2014年   3699篇
  2013年   4328篇
  2012年   4595篇
  2011年   6086篇
  2010年   5042篇
  2009年   5150篇
  2008年   5238篇
  2007年   5083篇
  2006年   5373篇
  2005年   4825篇
  2004年   4348篇
  2003年   4223篇
  2002年   4692篇
  2001年   4519篇
  2000年   3854篇
  1999年   3924篇
  1998年   2888篇
  1997年   2528篇
  1996年   1944篇
  1995年   1499篇
  1994年   1042篇
  1993年   751篇
  1992年   467篇
  1991年   343篇
  1990年   262篇
  1989年   200篇
  1988年   137篇
  1987年   87篇
  1986年   63篇
  1985年   42篇
  1984年   34篇
  1983年   29篇
  1982年   27篇
  1981年   16篇
  1980年   23篇
  1979年   18篇
  1976年   6篇
  1973年   5篇
  1951年   6篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Zhou  Hongtao  Xia  Liang  Su  Housheng 《Neural computing & applications》2022,34(19):16463-16472
Neural Computing and Applications - A new iterative method based on the event-triggered strategy for finding a solution to a mixed equilibrium problem (MEP) is introduced in this paper. The target...  相似文献   
72.
In electronic systems, dynamic random access memory (DRAM) is one of the core modules in the modern silicon computer. As for a bio‐computer, one would need a mechanism for storage of bio‐information named ‘data’, which, in binary logic, has two levels, logical high and logical low, or in the normalised form, ‘1’ and ‘0’. This study proposes a possible genetic DRAM based on the modified electronic configuration, which uses the biological reaction to fulfil an equivalent RC circuit constituting a memory cell. The authors implement fundamental functions of the genetic DRAM by incorporating a genetic toggle switch for data hold. The results of simulation verify that the basic function can be used on a bio‐storage module for the future bio‐computer.Inspec keywords: DRAM chips, genetic engineering, biocomputers, bioinformatics, equivalent circuits, RC circuitsOther keywords: dynamic genetic memory design, electronic systems, dynamic random access memory, modern silicon computer, biocomputer, bioinformation, binary logic, logical high level, logical low level, normalised form, genetic DRAM, modified electronic configuration, biological reaction, equivalent RC circuit, memory cell, fundamental functions, genetic toggle switch, data hold, biostorage module  相似文献   
73.
The issues of hydrogen generation and storage have hindered the widespread use and commercialization of hydrogen fuel cell vehicles.It is thus highly attractive,but the design and development of highly active non-noble-metal catalysts for on-demand hydrogen release from alkaline NaBH4 solution under mild conditions remains a key challenge.Herein,we describe the use of CoP nanowire array integrated on a Ti mesh (CoP NA/Ti) as a three-dimensional (3D) monolithic catalyst for efficient hydrolytic dehydrogenation of NaBH4 in basic solutions.The CoP NA/Ti works as an on/off switch for on-demand hydrogen generation at a rate of 6,500 mL/(min.g) and a low activation energy of 41 kJ/mol.It is highly robust for repeated usage after recycling,without sacrificing catalytic performance.Remarkably,this catalyst also performs efficiently for the hydrolysis of NH3BH3.  相似文献   
74.
75.
The mechanism of radiation-induced detwinning is different from that of deformation detwinning as the former is dominated by supersaturated radiation-induced defects while the latter is usually triggered by global stress. In situ Kr ion irradiation was performed to study the detwinning mechanism of nanotwinned Cu films with various twin thicknesses. Two types of incoherent twin boundaries (ITBs), so-called fixed ITBs and free ITBs, are characterized based on their structural features, and the difference in their migration behavior is investigated. It is observed that detwinning during radiation is attributed to the frequent migration of free ITBs, while the migration of fixed ITBs is absent. Statistics shows that the migration distance of free ITBs is thickness and dose dependent. Potential migration mechanisms are discussed.  相似文献   
76.
The solvent‐engineering method is widely used to fabricate top‐performing perovskite solar cells, which, however, usually exhibit inferior reproducibility. Herein, a two‐stage annealing (TSA) strategy is demonstrated for processing of perovskite films, namely, annealing the intermediate phase at 60 °C for the first stage then at 100 °C for the second stage. Compared to conventional direct annealing temperature (DHA) at 100 °C, using this strategy, MAPbI3 films become more controllable, leading to superior film uniformity and device reproducibility with the champion device efficiency reaching 19.8%. More specifically, the coefficient of variation of efficiency for 49 cells is reduced to 5.9%, compared to 9.8% for that using DHA. The TSA process is carefully studied using Fourier transform infrared spectroscopy, X‐ray diffraction, and UV–vis absorption spectroscopy. It is found that in comparison with DHA the formation of hydrogen bonding and crystallization of perovskite are much slower and can be better controlled when using TSA. The improvements in film uniformity and device reproducibility are attributed to: 1) controllable MAPbI3 crystal growth stemming from the progressive formation of hydrogen bonding between methylammonium and halide; 2) suppression of intermediate phase film dewetting, which is believed to be due to its decreased mobility at the initial low‐temperature annealing stage.  相似文献   
77.
78.
Mixed transition metal oxides (MTMOs) have received intensive attention as promising anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). In this work, we demonstrate a facile one-step water-bath method for the preparation of graphene oxide (GO) decorated Fe2(MoO4)3 (FMO) microflower composite (FMO/GO), in which the FMO is constructed by numerous nanosheets. The resulting FMO/GO exhibits excellent electrochemical performances in both LIBs and SIBs. As the anode material for LIBs, the FMO/GO delivers a high capacity of 1,220 mAh·g–1 at 200 mA·g–1 after 50 cycles and a capacity of 685 mAh·g–1 at a high current density of 10 A·g–1. As the anode material for SIBs, the FMO/GO shows an initial discharge capacity of 571 mAh·g–1 at 100 mA·g–1, maintaining a discharge capacity of 307 mAh·g–1 after 100 cycles. The promising performance is attributed to the good electrical transport from the intimate contact between FMO and graphene oxide. This work indicates that the FMO/GO composite is a promising anode for high-performance lithium and sodium storage.
  相似文献   
79.
开采沉陷信息处理软件系统模块划分方法的探讨   总被引:2,自引:1,他引:1  
对开采沉陷信息处理软件系统各个模块间的关系及设计原则进行了探讨.利用文中讨论的设计划分方法开发的“地表移动与三下采煤数据管理及处理”软件收到了良好的运行效果  相似文献   
80.
An experiment on fitness of one-piece casting osseointegrated implant frameworks was performed among three fixture abument positions where other conditions were controlled. The result revealed that there was statistically significant differences in dimensional change among the three fixture abument positions. In terms of the relation between abument position and fitness, the more backward the abument position was, the worse the osseointegrated framework fitness was. The frameworks showed deformations in "arch form" and "warp" in three dimensions.  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