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   268篇
  免费   5篇
  国内免费   1篇
化学   151篇
晶体学   2篇
力学   7篇
数学   17篇
物理学   97篇
  2023年   1篇
  2022年   6篇
  2021年   4篇
  2020年   2篇
  2019年   6篇
  2018年   7篇
  2017年   2篇
  2016年   19篇
  2015年   2篇
  2014年   5篇
  2013年   16篇
  2012年   19篇
  2011年   10篇
  2010年   6篇
  2009年   2篇
  2008年   20篇
  2007年   16篇
  2006年   9篇
  2005年   20篇
  2004年   14篇
  2003年   5篇
  2002年   11篇
  2001年   8篇
  2000年   3篇
  1999年   8篇
  1998年   4篇
  1997年   4篇
  1996年   1篇
  1995年   1篇
  1994年   4篇
  1993年   5篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1977年   3篇
  1973年   2篇
  1962年   1篇
  1958年   1篇
  1955年   1篇
  1937年   2篇
排序方式: 共有274条查询结果,搜索用时 31 毫秒
51.
A numerical approach based on a recently proposed discretization technique and suitable for molecular weight calculation in emulsion polymerization is presented. The main features of this approach are (i) the direct evaluation of the complete chain length distribution without the need of predefined model distributions (as in the case of moment based methods), (ii) the large flexibility when defining the computational grid, (iii) the capability of evaluating with accuracy two integral properties of the distribution no matter how coarse the grid is and (iv) the limited computational effort required. Selected applicative examples are reported with emphasis on cases where other computational approaches give unreliable or less detailed results.  相似文献   
52.
Let (X,?) be a partially ordered set and d be a complete metric on X. Let F,G be two set-valued mappings on X. We obtained sufficient conditions for the existence of common fixed point of F and G satisfying an implicit relation in partially ordered set X.  相似文献   
53.
Functional electrode materials play an increasingly important role in the advancement of energy conversion and storage technologies used in batteries, electrolyzers, supercapacitors, fuel cells, and other electrochemical devices. To address the problems related to accelerating demand for the so-called renewable energy, which are simultaneously coupled with environmental concerns, new generations of materials, engineering methodologies, and innovative techniques are necessary. Among many synthetic methods, microwave-assisted synthesis becomes nowadays a very popular approach to efficiently control both the composition and morphology of solids. In this review, we focus on its applications to create new advanced energy electrode materials.
Graphical abstract A schematic illustration of microwave-assisted synthesis process for making functional electrode materials
  相似文献   
54.
The hierarchical self‐assembly of an amphiphilic block copolymer, poly(N,N‐dimethylacrylamide)‐block‐polystyrene with a very short hydrophilic block (PDMA10b‐PS62), in large granular nanoparticles is reported. While these nanoparticles are stable in water, their disaggregation can be induced either mechanically (i.e., by applying a force via the tip of the cantilever of an atomic force microscope (AFM)) or by partial hydrolysis of the acrylamide groups. AFM force spectroscopy images show the rupture of the particle as a combination of collapse and flow, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of partly hydrolyzed nanoparticles provide a clear picture of the granular structure.

  相似文献   

55.
We report on the versatile effect of weak red laser light impinging on diblock copolymer [poly(isoprene-b-styrene)] dispersions in two selective solvents for each block. In the strongly scattering but transparent micellar solutions in hexane (a good solvent for polyisoprene), higher refractive index copolymer-rich fibers were formed. In the turbid dispersions of the same copolymer in ethyl acetate (a good solvent for polystyrene), the effect of self-induced transparency was observed. A two-step patterning mechanism caused the generation of a transparent microchannel, increasing light transmission. The analogy between the current effect and that observed in homopolymer polyisoprene solutions in different solvents is discussed toward an understanding of the unanticipated light-soft-matter interaction.  相似文献   
56.
The present study deals with the electrochemical investigation of seven different phenols through cyclic voltammetry (CV). Phenols can be partly eliminated from aqueous solutions by electrochemically initiated polymerization. Thus, the basic CV behavior was studied under the optimized conditions such as; pH of the medium, concentration of the analyte, the supporting electrolyte, potential window, and scan rate. The CV curves of all of the phenols showed that the electro-polymerization phenomenon on the electrode surface causes surface fouling for further electrooxidation of these compounds. The influence of substituents in the ring was especially noted in terms of their tendency to foul the electrode surface. The formation of new intermediates during the electrooxidation was observed whose nature was found to be highly dependent on the type and position of the substituent. As far as the influence of pH is concerned, phenols in basic medium were electrooxidized earlier but with low current. Difference in CV response because of the substituent attached under varied pH was also noted. From the diffusion coefficient (D) and heterogeneous rate constant (k sh) mixed nature of electron transfer process was proposed.  相似文献   
57.
The phase separation of the polymer blend polystyrene/poly(methyl phenyl siloxane) (PS/PMPS) is studied in situ by laser scanning confocal microscopy (LSCM) and by fluorescence correlation spectroscopy (FCS) at macroscopic and microscopic length scales, respectively. It is shown for the first time that FCS when combined with LSCM can provide independent information on the local concentration within the phase‐separated domains as well as the interfacial width.  相似文献   
58.
Fusion cross-sections for the 7Li + 12C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections due to the breakup of 7Li may not be significant for 7Li + 12C reaction at energies around the barrier.  相似文献   
59.
Dual detection systems are of interest for rapid, accurate data collection in sensing systems and in vitro testing. We introduce an IrIII complex with a boronic acid receptor site attached to the 2-phenylpyridine ligand as an ideal probe with photo- and electrochemical signals that is sensitive to monosaccharide binding in aqueous solution. The complex displays orange luminescence at 618 nm, which is reduced by 70 and 40 % upon binding of fructose and glucose, respectively. The electro-chemiluminescent signal of the complex also shows a direct response to monosaccharide binding. The IrIII complex shows the same response upon incorporation into hydrogel matrices as in solution, thus demonstrating the potential of its integration into a device, as a nontoxic, simple-to-use tool to observe sugar binding over physiologically relevant pH ranges and saccharide concentrations. Moreover, the complex's luminescence is responsive to monosaccharide presence in cancer cells.  相似文献   
60.
Tattooing is a ubiquitous body modification involving the injection of ink and/or dye pigments into the dermis. Biosensors in the form of tattoos can be used to monitor metabolites in interstitial fluid. Here, minimally invasive, injectable dermal biosensors were developed for measuring pH, glucose, and albumin concentrations. The dermal pH sensor was based on methyl red, bromothymol blue, and phenolphthalein, which responded to a pH range from 5.0 to 9.0. The dermal glucose sensor consisted of glucose oxidase, 3,3′,5,5′‐tetramethylbenzidine, and peroxidase that detected concentrations up to 50.0 mmol L?1. The dermal albumin sensor consisted of 3′,3′′,5′,5′′‐tetrachlorophenol‐3,4,5,6‐tetrabromosulfophthalein to measure concentrations up to 5.0 g L?1. The sensors were multiplexed in ex vivo skin tissue and quantitative readouts were obtained using a smartphone camera. These sensors can be used to manage of acid–base homeostasis, diabetes, and liver failure in point‐of‐care settings.  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