首页 | 官方网站   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   27758篇
  免费   2498篇
  国内免费   1380篇
工业技术   31636篇
  2024年   60篇
  2023年   480篇
  2022年   774篇
  2021年   1165篇
  2020年   871篇
  2019年   740篇
  2018年   840篇
  2017年   908篇
  2016年   815篇
  2015年   1094篇
  2014年   1473篇
  2013年   1796篇
  2012年   1892篇
  2011年   2163篇
  2010年   1844篇
  2009年   1780篇
  2008年   1806篇
  2007年   1622篇
  2006年   1551篇
  2005年   1386篇
  2004年   922篇
  2003年   761篇
  2002年   719篇
  2001年   630篇
  2000年   608篇
  1999年   575篇
  1998年   445篇
  1997年   411篇
  1996年   343篇
  1995年   283篇
  1994年   251篇
  1993年   165篇
  1992年   146篇
  1991年   83篇
  1990年   65篇
  1989年   33篇
  1988年   44篇
  1987年   28篇
  1986年   16篇
  1985年   7篇
  1984年   10篇
  1983年   6篇
  1982年   8篇
  1981年   7篇
  1980年   5篇
  1979年   2篇
  1959年   2篇
  1951年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
赵勤  回璇 《包装工程》2021,42(10):323-333
目的 赣傩艺术元素内容丰富并保存完整,是研究我国古代赣傩地区文化与艺术的珍贵史料.研究赣傩艺术元素的提取及衍生图案的设计方法,在设计应用中表达赣傩傩面具、选取傩舞形和构筑傩庙魂,能给当代赣傩艺术元素的产品设计以指引.方法 通过直接引用、形意结合和局部强化的设计方法,增厚其丰富内涵、设计个性和主题意蕴.通过现代化审美中"绿色化、感性化、地域化"的要求,遵循"以退为进,化繁为简""多元并存,个性体现"的原则,强化赣傩艺术元素的独特风格.结论 用现代的手法,将特色的赣傩艺术元素植入到理性的产品设计中去,使赣傩艺术元素与现代设计思想有机结合.在继承传统文化与现代流行中找到契合点,深入挖掘赣傩艺术元素蕴含的文化精神、文化胸怀和文化自信,使中华传统文化在现代审美下进行创新再现.  相似文献   
12.
In the present research,nutrient broth(NB)medium was identified to be able to neutralize the antibac-terial activity of chitosan and its derivatives.Therefore,an improved test method independent of NB medium was proposed to precisely quantify the antibacterial effectiveness and efficiency of chitosan.The minimum bactericidal concentration(MBC)of chitosan was 60 μg mL-1 against S.aureus and E.coli,and 0.01%(w/v)chitosan could kill 100%of bacteria within 3 min.From another point of view,the neutralizing efficiency of NB could be tripled by adding 25 g L-1 of sodium chloride.Then the neutraliz-ing mechanism of NB medium was ascribed to flocculation between chitosan and protein.Adding extra sodium chloride could significantly reduce the size of floccules,and smaller floccules would lose the ability of binding with bacteria directly,showing higher neutralizing rate on the macro scale.  相似文献   
13.
Organic solar cells (OSCs) have recently reached a remarkably high efficiency and become a promising technology for commercial application. However, OSCs with top efficiency are mostly processed by halogenated solvents and with additives that are not environmentally friendly, which hinders large-scale manufacture. In this study, high-performance tandem OSCs, based on polymer donors and two small-molecule acceptors with different bandgaps, are fabricated by solution processing with non-halogenated solvents without additive. Importantly, the two active layers developed from non-halogenated solvents show better phase segregation and charge transport properties, leading to superior performance than halogenated ones. As a result, a tandem OSC with high efficiency of up to 16.67% is obtained, showing unique advantages in future massive production.  相似文献   
14.
Yang  Kai  Yan  Xiao  Wang  Qian  Qin  Kaiyu 《Wireless Networks》2021,27(6):4051-4064
Wireless Networks - This paper considers the performance of non-orthogonal multiple-access (NOMA) with full-duplex (FD) relaying system in the presence of two practical undesirable defects, namely...  相似文献   
15.
The strengthening method of multi-element M-site solid solution is a common approach to improve mechanical properties of MAX phase ceramic. However, the research on capability of multi-element A-site solid solution to improve mechanical properties has rarely been reported. Thereupon, quasi-high-entropy MAX phase ceramic bulks of Ti2(Al1?xAx)C and Ti3(Al1?xAx)C2 (A = Ga, In, Sn, x = 0.2, 0.3, 0.4) were successfully synthesized by in situ vacuum hot pressing via multi-elements solid solution. The multi-elements solid solution in single-atom thick A layer was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy as well as by energy dispersive X-ray spectroscopy mappings. Effects of doped multi-elements contents on the phase, microstructure, mechanical properties, and high temperature tribological behaviors were studied. Results demonstrated that the Vickers hardness, anisotropic flexural strength, fracture toughness, and tribological properties of Ti–Al–C based MAX ceramics could be remarkably improved by constitution of quasi-high-entropy MAX phase in A layers. Moreover, the strengthening and wear mechanisms were also discussed in detail. This method of multi-element solid solution at A-site provides new way to enhance mechanical properties of other MAX phase ceramics.  相似文献   
16.
目的是利用高维量子纠缠态为量子信道,讨论未知单粒子态的受控隐形传输问题。以三维量子纠缠态为信道,提出一个二维任意单粒子态的受控隐形传输协议。提出了以任意[d]-维量子纠缠态为量子信道,[t]-维任意单粒子态的隐形传输协议[(t相似文献   
17.
18.
大型货物的装填过程中影响载荷的因素较多,其中对中精度对装填载荷影响较为明显。通过动力学仿真软件ADAMS对装填过程中载荷进行模拟,并对各影响因素进行定量分析,得到对中偏差与装填载荷的关系。将仿真结果与试验数据进行对比,验证该仿真方法的正确性,可作为后续研究装填载荷的一种方法,为结构设计提供指导。  相似文献   
19.
20.
Tritium management is one of the most critical issues that limit the development of fluoride‐salt‐cooled high‐temperature reactor (FHR); therefore, it is important to figure out the tritium transport characteristics in FHRs. In this paper, 3 works concerning about tritium in FHR are conducted: first, the tritium transport characteristics in the primary loop of FHRs are introduced, including tritium production and speciation, the absorption and desorption by graphite, dissolution and diffusion in molten salt, and permeation through structural materials. Second, the physical and mathematical models are established for tritium transport characteristic analysis in a transportable FHR (TFHR). The tritium transport characteristic analysis code (TAPAS) for TFHR is developed and benchmarked. The results prove the fidelity and accuracy of TAPAS. Finally, the tritium transport characteristics in the TFHR are analyzed systematically by TAPAS. Three conclusions are obtained: (1) tritium in the primary coolant loop is mainly in the form of T2; (2) when TFHR operates at steady state, the permeation rate of T2 can be regarded as a constant (9.03 × 109 Bq ? EFPD?1 ); and (3) 7Li enrichment and redox potential of molten salt have great influence on the tritium distribution. This work might provide contribution to the tritium control in FHRs.  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-23

京公网安备 11010802026262号