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   1595篇
  免费   217篇
  国内免费   479篇
化学   1033篇
晶体学   31篇
力学   24篇
综合类   12篇
数学   533篇
物理学   658篇
  2023年   14篇
  2022年   21篇
  2021年   26篇
  2020年   37篇
  2019年   30篇
  2018年   41篇
  2017年   45篇
  2016年   66篇
  2015年   95篇
  2014年   104篇
  2013年   157篇
  2012年   195篇
  2011年   234篇
  2010年   155篇
  2009年   194篇
  2008年   141篇
  2007年   153篇
  2006年   127篇
  2005年   71篇
  2004年   63篇
  2003年   50篇
  2002年   45篇
  2001年   41篇
  2000年   35篇
  1999年   47篇
  1998年   27篇
  1997年   17篇
  1996年   18篇
  1995年   7篇
  1994年   10篇
  1993年   8篇
  1992年   4篇
  1991年   5篇
  1990年   4篇
  1986年   1篇
  1936年   3篇
排序方式: 共有2291条查询结果,搜索用时 234 毫秒
91.
正There is currently considerable interest in the development of fluorescent molecular probes for use in sensitive sensing and imaging applications.The design,synthesis and application of fluorescent molecular probes that selectively and specifically respond to the presence of a specific analyte is a multidisciplinary research area involving numerous fields of modern science and medicine,including molecular biology,chemical biology,biophysics,clinical diagnosis and analytical/environmental chemistry,etc.For sensing application,advances in the understanding of molecular probe structure  相似文献   
92.
For grafting polypyrrole layers on oxidic substrates, the synthesis and characterization of a new adhesion promoter 11‐(pyrrol‐3‐yl) undecyl trimethoxysilane (PyTMS) were described in this article. The oxidation potential of PyTMS was determined by cyclic voltammetry. The grafting behavior of such an adhesion promoter on oxidized surface and chemical deposition of polypyrrole over the modified oxidized surface were studied. The adsorbed layer on the oxidized substrates thus formed was determined by both contact angle measurements and X‐ray photoelectron spectroscopy. Chemical polymerization of terminal pyrrole moieties on such substrates yielded adhesive polypyrrole films, and SEM image showed that the morphology of the polypyrrole films was influenced by the experimental conditions.  相似文献   
93.
The bottom‐up filling capabilities of electroless copper plating bath with an addition of additives, such as polyethylene glycol (PEG), polypropylene glycol (PPG) and triblock copolymers of PEG and PPG with ethylene oxide terminal blocks termed EPE, were investigated by the cross‐sectional scanning electron microscopy (SEM) observation of sub‐micrometer trenches. Though three additives had inhibition for electroless copper deposition, the suppression degrees of three additives were different. EPE‐2000 had the strongest suppression for electroless copper deposition, and the suppression of PEG‐2000 was the weakest. The bottom‐up filling capability of electroless copper was investigated in a plating bath containing different additives with the concentration of 2.0 mg/L. The cross‐sectional SEM observation indicated the trenches with the width of 280 nm and the depth of 475 nm were all completely filled by the plating bath with an addition of EPE‐2000, but the trenches were not completely filled by the plating bath with an addition of PEG‐2000 or PPG‐2000, and some voids appeared. Linear sweep voltammetry measurement indicated that three additives all inhibited the cathodic reduction reaction and the anodic oxidation reaction, and the inhibition of EPE‐2000 was the strongest among three additives, which agreed with that of the deposition rate of electroless copper. Significant differences in surface roughness of deposited copper film were observed by UV‐visible near‐infrared for different suppressors, and the bright and smooth of deposited copper film were in accordance with the inhibition of three additives.  相似文献   
94.
In this note, the relationships between the expectation and variance in operator probability theory and numerical range of operators are considered.  相似文献   
95.
A noncentral ring-shaped potential is proposed in which the noncentral electric dipole and a novel angle-dependent component are included, the radial part is selected as the Coulomb potential or the harmonic oscillator potential. The exact solution of the Schr?dinger equation with this potential is investigated by working in a complete square integrable basis that supports a tridiagonal matrix representation of the wave operator. The resulting three-term recursion relation for the expansion coefficients of the wavefunctions (both angular and radial) are presented. The angular/radial wavefunction is written in terms of the Jacobi/Laguerre polynomials. The discrete spectrum of the bound states is obtained by diagonalization of the radial recursion relation.  相似文献   
96.
This paper continues the analysis on the Lengyel–Epstein reaction- diffusion system of the chlorite-iodide-malonic acid-starch (CIMA) reaction for the rich Turing structures. The steady state structures, especially the double bifurcation one, and their stability and multiplicity are studied by the use of Lyapunov–Schmidt reduction technique and singularity theory. Numerical simulations are presented to support our theoretical studies. The results show that the richer stationary Turing patterns heavily rely both on the size of the reactor and on the effective diffusion rate in the CIMA reaction.  相似文献   
97.
An efficient and reusable heterogeneous catalytic assembly of PdCl2 held in ionic liquid brushes has been synthesized and an environmentally‐friendly procedure was developed for coupling aryl iodides with acrylic acid. These reactions were conducted in water under aerobic conditions with water‐insoluble or even solid aryl iodides and they proceeded smoothly and cleanly without any organic co‐solvent or other additives. A 0.5 mol% (based on Pd atom) dose of the catalyst was found to be sufficient for Mizoroki–Heck reaction. The catalyst is easily recovered post reaction, via simple filtration, and reused at least eight times without a noticeable loss of activity. The protocol has the advantages of excellent yield, environmental friendliness, and catalyst recyclability. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
98.
In this paper, the structure of Jordan higher derivable maps on triangular algebras by commutative zero products is given. As an application, the form of Jordan higher derivable maps of nest algebras by commutative zero products is obtained.  相似文献   
99.
Multi‐analyte real‐time interrogation of cellular activity allows for the potential discovery of novel insights into disease. In this report, the addition of electrochemical biosensors to a previously developed platform utilizing Au microfabricated electrodes was explored. Glucose oxidase was immobilized at the electrode surface with an osmium redox polymer, using hand‐casting and electrodeposition techniques, allowing for the first comparison of deposition techniques at a Au microfabricated array. This preliminary work is the first step toward the goal of creating a multi‐analyte array for cellular analysis.  相似文献   
100.
《中国化学快报》2022,33(9):4380-4384
Carbon dioxide electrochemical reduction (CO2RR) has been recognized as an efficient way to mitigate CO2 emissions and alleviate the pressure on global warming and associated environmental consequences. Gold (Au) is reported as stable and active electrocatalysts to convert CO2 to CO at low overpotential due to its moderate adsorption strength of *COOH and *CO. The request for improved catalytic performance, however, is motivated by current unsatisfied catalytic selectivity because of the side hydrogen evolution reaction. In this context, the design of Au based binary catalysts that can boost CO selectivity is of great interest. In the present work, we report that Au nanoparticles can be feasibly dispersed and anchored on silicon nanowires to form Au-Si binary nanomaterials. The Au-Si may stably drive CO2RR with a CO Faraday efficiency of 95.6% at ?0.6 V vs. RHE in 0.5 mol/L KHCO3 solution. Such selectivity outperforms Au particles by up to 61%. Controlled experiments illustrate that such catalytic enhancement can chiefly be ascribed to electronic effects of binary catalysts. Theoretical calculations reveal that spontaneously produced silicon oxide may not only inhibit hydrogen evolution reaction, but also stabilize the key intermediate *COOH in CO formation.  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