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   1093篇
  免费   275篇
  国内免费   13篇
电工技术   3篇
综合类   26篇
化学工业   619篇
金属工艺   8篇
机械仪表   15篇
矿业工程   3篇
能源动力   1篇
轻工业   17篇
石油天然气   11篇
武器工业   2篇
无线电   212篇
一般工业技术   445篇
冶金工业   6篇
原子能技术   5篇
自动化技术   8篇
  2024年   10篇
  2023年   70篇
  2022年   39篇
  2021年   70篇
  2020年   97篇
  2019年   71篇
  2018年   96篇
  2017年   67篇
  2016年   70篇
  2015年   78篇
  2014年   91篇
  2013年   94篇
  2012年   85篇
  2011年   87篇
  2010年   38篇
  2009年   54篇
  2008年   41篇
  2007年   36篇
  2006年   34篇
  2005年   33篇
  2004年   16篇
  2003年   12篇
  2002年   9篇
  2001年   12篇
  2000年   7篇
  1999年   12篇
  1998年   6篇
  1997年   5篇
  1996年   5篇
  1995年   5篇
  1994年   3篇
  1993年   6篇
  1992年   4篇
  1991年   2篇
  1990年   3篇
  1989年   3篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1983年   1篇
  1982年   2篇
  1979年   1篇
  1951年   1篇
排序方式: 共有1381条查询结果,搜索用时 31 毫秒
61.
在水热法条件下,以N,N-二甲基甲酰胺(DMF)和水(VDMF∶VH2O=2∶1)为溶剂,基于1,2,4,5-苯四甲酸(H4BTA)、咪唑(Im)和氯化钴(CoCl2.6H2O)合成了一维链状配合物[Co(Im)2(H4BTA)0.5]n(1)。晶体结构分析表明:该配合物属于三斜晶系,P1空间群,在不对称结构单元中一个钴原子与两个咪唑中的两个氮原子、H4BTA中的一个氧原子配位。同时,配合物(1)通过分子间和一维链间氢键作用形成三维超分子。  相似文献   
62.
为提高飞机起落架载荷实测精度,以支柱式起落架结构为研究对象,探讨处理其载荷标定数据的工程方法。首先,对实际受载情况和单向加载工况标定数据的分析,挖掘出三向载荷、缓冲支柱压缩行程与应变码值间的数学关系,将预测的数学关系代入到多向工况的标定数据中,验证了它们的准确性;其次,根据两种标定数据回归方法,提出了对应使用的支柱式起落架载荷-应变标定方程的数学模型;最后,将两种标定方程代回到标定数据中,计算起落架三向载荷,所有反算载荷的误差均在可控范围内,表明标定方程满足精度要求。将标定方程代入实测数据中,实测曲线符合变化规律。该处理方法的应用能有力提高支柱式起落架的起飞-着陆载荷实测和载荷谱编制的准确度。  相似文献   
63.
64.
The fabrication of chiral nanostructures gives rise to characteristic chiroptical activity, which can be used for chirality‐based biosensors. Great progress is made in the use of nanoassemblies for the construction of chiral nanoparticle dimers, pyramids, helices, and twisted structures, and their chiroptical activities correlate with diverse structural geometries and enantiomeric configurations. In DNA‐hybridization‐based chiral nanoassemblies, the assembly parameters, such as the components, gaps, multicomponents, and the aftergrowth of metal, can result in multiple bands and enhanced chiroptical effects. Based on known chiral nanostructures, the existing chiral nanoassembly‐based biosensors together with their targets and signal amplification strategies are reviewed. Chirality involves multiple signals, and multitarget biosensors are introduced with newly developed chiral architectures for the accurate and reliable monitoring of biomarkers in living cells. The interactions between chiral nanoarchitectures and biosystems are also highlighted, which are important not only in the chiral dynamic switching of nano‐objects for biomonitoring, but also in manipulating cell growth, proliferation, and adhesion. The future perspectives on chiral fabrication and its use in biosensors are also comprehensively discussed.  相似文献   
65.
Efforts to further extend the range of applications of polymer based materials have resulted in the recent production of healable polymers that can regain their strength after damage. Within this field of healable materials, supramolecular polymers have been subject to extensive investigation. By virtue of their reversible non‐covalent interactions, cracks and fractures in such polymers can be readily and repeatedly healed in order to regain key physical properties. However, many supramolecular polymers are relatively weak and elastomeric in nature, which renders them unsuitable for high strength structural applications. To overcome these deficiencies, preliminary studies have shown that it is possible to reinforce supramolecular polymers with microscale and nanoscale fillers to afford composites that are not only stronger and stiffer compared with the polymers alone but also retain their healing abilities. In this minireview we discuss the evolution of these supramolecular composites and their advantages over more conventional, covalent polymeric materials. © 2014 Society of Chemical Industry  相似文献   
66.
A macroporous silica‐based 1,3‐[(2,4‐diethyl‐heptylethoxy)oxy]‐2,4‐crown‐6‐calix[4]arene (Calix[4]arene‐R14) supramolecular recognition polymeric composite, (Calix[4]+Oct)/SiO2‐P, was synthesized. It was performed by impregnating and immobilizing Calix[4]arene‐R14 and n‐octanol into the pores of the macroporous SiO2‐P particles support. n‐Octanol was used to modify Calix[4]arene‐R14 through hydrogen bonding. The effect of eight typical fission products contained in highly active liquid waste (HLW) on the adsorption of Cs(I), one of the heat generators, was investigated at 298 K by examining the effect of contact time and the HNO3 concentration in a range of 0.3–7.0 M. (Calix[4]+Oct)/SiO2‐P showed excellent adsorption ability and high selectivity for Cs(I) at 4.0 M HNO3 over the tested elements. The partitioning of Cs(I) from a simulated HLW was operated by (Calix[4]+Oct)/SiO2‐P packed column. Cs(I) was able to be effectively eluted by water and separated from the tested metals. It is demonstrated that (Calix[4]+Oct)/SiO2‐P is promising to apply in chromatographic separation of Cs(I) from HLW. © 2010 American Institute of Chemical Engineers AIChE J, 2010  相似文献   
67.
68.
A new nanoparticle/block copolymer (NP/BCP) hybrid material combining the unique properties of BCP poly(styrene)‐b‐poly(d ‐lactide) (PS‐b‐PDLA) and inorganic NP quantum dots CdSe was developed. A systematic study on the microphase separation of a series of PS‐b‐PDLAs by small‐angle X‐ray scattering showed that the degree of order of the separated microdomains depended on the initial state of the BCP and the measurement temperature and can be improved through isothermal crystallization of PDLA, thermal annealing and shear field etc. Incorporating a small amount of NPs into the BCP matrix can improve the mobility of the polymer chains and thus promote self‐assembly of the BCP, which leads to hierarchically ordered structures. Excess NPs, however, cannot be completely incorporated into the PDLA domains, resulting in the phase transformation of the BCP, destruction of the ordered structure and even macroscopic phase separation due to the aggregation of NPs. An important observation is that stereocomplexation between PDLA and poly(l ‐lactide) could provide a driving force to promote microphase separation of the BCP. The strategy presented in the current work has potential applications for developing highly ordered NP/BCP hybrid materials. © 2014 Society of Chemical Industry  相似文献   
69.
70.
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