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   5959篇
  免费   670篇
  国内免费   299篇
电工技术   350篇
综合类   414篇
化学工业   1039篇
金属工艺   348篇
机械仪表   401篇
建筑科学   470篇
矿业工程   169篇
能源动力   204篇
轻工业   393篇
水利工程   124篇
石油天然气   266篇
武器工业   74篇
无线电   716篇
一般工业技术   703篇
冶金工业   376篇
原子能技术   82篇
自动化技术   799篇
  2024年   50篇
  2023年   129篇
  2022年   248篇
  2021年   381篇
  2020年   254篇
  2019年   190篇
  2018年   240篇
  2017年   225篇
  2016年   233篇
  2015年   281篇
  2014年   377篇
  2013年   372篇
  2012年   472篇
  2011年   430篇
  2010年   389篇
  2009年   328篇
  2008年   267篇
  2007年   244篇
  2006年   247篇
  2005年   201篇
  2004年   169篇
  2003年   144篇
  2002年   133篇
  2001年   111篇
  2000年   112篇
  1999年   117篇
  1998年   101篇
  1997年   96篇
  1996年   66篇
  1995年   60篇
  1994年   57篇
  1993年   38篇
  1992年   32篇
  1991年   19篇
  1990年   20篇
  1989年   17篇
  1988年   14篇
  1987年   6篇
  1986年   8篇
  1985年   4篇
  1984年   5篇
  1982年   7篇
  1981年   6篇
  1980年   5篇
  1979年   4篇
  1978年   2篇
  1976年   5篇
  1975年   3篇
  1974年   2篇
  1973年   3篇
排序方式: 共有6928条查询结果,搜索用时 0 毫秒
91.
Whelk‐like polypyrrole (PPy) arrays film is successfully prepared by electropolymerization of pyrrole in the presence of low‐surface‐energy tetraethylammonium perfluorooctanesulfonate (TEAPFOS) as dopant. The underwater wettability of PPy whelk‐like arrays can be successfully tuned by electrical doping/dedoping of PFOS ions. Interestingly, CCl4 droplets with microliter‐size as a representative sample are gathered together to form a larger droplet underwater at the potential of +0.8 V (vs Ag/AgCl), because PPy is in its PFOS‐doped states. Note that CCl4 droplet can climb uphill successfully on the inclined whelk‐like arrays PPy film under the applied potential of ?1.0 V (vs Ag/AgCl), which may be attributed to wettability gradient derived from different oxidation states of PPy induced by electrochemical potential. These results may provide a simple strategy for on‐demand manipulation of organic droplets underwater at low voltage.  相似文献   
92.
93.
Teng Long  Di Wu  Xin Chen  Xiaosong Guo  Li Liu 《工程优选》2016,48(6):1019-1036
Space-filling and projective properties of design of computer experiments methods are desired features for metamodelling. To enable the production of high-quality sequential samples, this article presents a novel deterministic sequential maximin Latin hypercube design (LHD) method using successive local enumeration, notated as sequential-successive local enumeration (S-SLE). First, a mesh-mapping algorithm is proposed to map the positions of existing points into the new hyper-chessboard to ensure the projective property. According to the maximin distance criterion, new sequential samples are generated through successive local enumeration iterations to improve the space-filling uniformity. Through a number of comparative studies, several appealing merits of S-SLE are demonstrated: (1) S-SLE outperforms several existing LHD methods in terms of sequential sampling quality; (2) it is flexible and robust enough to produce high-quality multiple-stage sequential samples; and (3) the proposed method can improve the overall performance of sequential metamodel-based optimization algorithms. Thus, S-SLE is a promising sequential LHD method for metamodel-based optimization.  相似文献   
94.
95.
交互性在提升电商网站用户忠诚中的应用策略分析   总被引:1,自引:1,他引:0  
苗秀  韩冬楠  王腾 《包装工程》2016,37(12):143-148
目的对电商网站的交互性进行分析。方法通过文献调研划分交互行为,在竞品分析和深度访谈等定性研究的基础上,编撰调查问卷并开展大规模调查,回收定量数据,结合电商网站的特性,运用SPSS主成分分析法对交互因子进行提取研究。结论电商网站的交互因子可以概括为相关性、真实性和关系性3个方向,从信息交互和社会交互两个维度有针对性地探索各交互因子的应用策略,可以有效提升电商网站的用户忠诚。  相似文献   
96.
The main objective of this work was to investigate the uptake channels of skin cells through which coumarin 6, transported by deoxycholate‐mediated liposomes (DOC‐LS), was internalised; this was also compared against the action of conventional LS. Coumarin 6‐loaded DOC‐LS and LS were characterised for size distribution, zeta potential, and shape, and analysed in vitro in human epidermal immortal keratinocyte (HaCaT) (epidermal) and human embryonic skin fibroblast (CCC‐ESF‐1) (dermal) cell lines. Various endocytosis inhibitors were incubated with cells treated with the nanocarriers. Flow cytometry results indicated that HaCaT and CCC‐ESF‐1 cells internalise the tested preparations through pinocytotic vesicles, macropinocytosis, clathrin‐mediated endocytic pathways, and via lysosomes, which consume a considerable amount of energy. The endocytosis pathways of DOC‐LS and LS showed no difference. This study provides a basis for the application of LS being combined with a microneedle system for efficient intracellular drug delivery, targeting cutaneous histocyte disorders.Inspec keywords: drugs, nanoparticles, lipid bilayers, nanomedicine, biomedical materials, electrokinetic effects, biomembrane transport, drug delivery systems, skin, organic compoundsOther keywords: dermal delivery, CCC‐ESF‐1 cells, skin cells, deoxycholate‐mediated liposomes, coumarin 6‐loaded DOC‐LS, endocytosis inhibitors, clathrin‐mediated endocytic pathways, endocytosis pathways, HaCaT cell lines, size distribution, zeta potential, nanocarriers, flow cytometry, pinocytotic vesicles, macropinocytosis, microneedle system, efficient intracellular drug delivery, targeting cutaneous histocyte disorders  相似文献   
97.
本文通过对CAI电磁学实验预习系统的具体开发过程的介绍,在分析其可行性与优越性的基础上,对如何进行此项工作进行初步探讨。  相似文献   
98.
提出了一种NURBS曲面的显示算法,该算法在通常参数曲面以网格形式显示的基础上,用小曲面片代替小平面片,利用曲线上部分点的切矢来决定显示曲线的点密度,同时增加了精度和速度控制的参数,使得显示的曲面更加光滑、流畅且易于控制。  相似文献   
99.
A. Chamoli and C.M. Bhandari presented a secure direct communication based on ping-pong protocol[Quantum Inf. Process. 8, 347 (2009)]. M.Naseri analyzed its security and pointed out that in this protocol any dishonest party can obtain all the other one’s secret message with zero risk of being detected by using fake entangled particles (FEP attack) [M. Naseri, Quantum Inf. Process. online]. In this letter, we reexamine the protocol’s security and discover that except the FEP attack, using a special property of GHZ states, any one dishonest party can also take a special attack, i.e., double-CNOT(Controlled NOT) attack. Finally, a denial-of-service attack is also discussed.  相似文献   
100.
RS485总线是工业中常用的通讯总线,相比RS232总线,其具有传输距离远、成本低等优势;以太网是互联网中最主流的组网方式。通过RS485总线与以太网混合,构建物联网系统,可低成本高效率地整合校园内各末端设备和设施。  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