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   409篇
  免费   206篇
  国内免费   185篇
化学   379篇
晶体学   12篇
力学   60篇
综合类   20篇
数学   6篇
物理学   323篇
  2024年   3篇
  2023年   5篇
  2022年   20篇
  2021年   8篇
  2020年   7篇
  2019年   5篇
  2018年   9篇
  2017年   10篇
  2016年   9篇
  2015年   6篇
  2014年   126篇
  2013年   47篇
  2012年   27篇
  2011年   36篇
  2010年   60篇
  2009年   52篇
  2008年   19篇
  2007年   28篇
  2006年   19篇
  2005年   28篇
  2004年   31篇
  2003年   63篇
  2002年   29篇
  2001年   33篇
  2000年   17篇
  1999年   5篇
  1998年   15篇
  1997年   11篇
  1996年   7篇
  1995年   8篇
  1994年   13篇
  1993年   7篇
  1992年   4篇
  1991年   11篇
  1990年   7篇
  1989年   9篇
  1988年   3篇
  1987年   2篇
  1985年   1篇
排序方式: 共有800条查询结果,搜索用时 31 毫秒
111.
徐香玉  王浩  杜中玉  毛旭艳  姜靓  孙德志 《化学通报》2016,79(3):279-282,231
通过化学还原法合成了球形银纳米颗粒,并利用电子显微镜方法对其形貌进行了表征;利用紫外可见吸收光谱法(UV)、荧光光谱法(FL) 以及扫描电子显微镜(SEM) 研究了球形纳米银与人血清白蛋白(HSA) 的结合反应。随着纳米银溶液浓度的增加,混合溶液的紫外吸收峰强度增加,但荧光强度则发生了明显的猝灭。光谱学实验结果表明,球形纳米银与人血清白蛋白在溶液中发生了相互作用,此结果也通过扫描电子显微镜实验得到了验证。由荧光实验还可获得纳米银与HSA 相互作用的结合常数、结合位点数以及吉布斯自由能变,由这些热力学数据可知纳米银与人血清白蛋白可以自发结合发生反应,并形成缔合物。  相似文献   
112.
王震遐  竺建康  任翠兰  张伟 《物理学报》2009,58(7):5046-5050
通过溶解C60的CCl4溶液在大气中的慢蒸发可以合成C59N和C19N晶体,这项实验结果为CnN(n≤59)晶体研究开辟了一种简单而有效的途径. 关键词: 富勒烯晶体 飞行时间质谱 透射电子显微镜 X射线光电子能谱  相似文献   
113.
As a component of near-field scanning optical microscope (NSOM), optical fiber probe is an important factor influncing the equipment resolution. Electroless nickel plating is introduced to metallize the optical fiber probe. The optical fibers are etched by 40% HF with Turner etching method. Through pretreatment, the optical fiber probe is coated with Ni-P film by electroless plating in a constant temperature water tank. Atomic absorption spectrometry (AAS), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDXS) are carried out to characterize the deposition on fiber probe. We have reproducibly fabricated two kinds of fiber probes with a Ni-P film: aperture probe and apertureless probe. In addition, reductive particle transportation on the surface of fiber probe is proposed to explain the cause of these probes.  相似文献   
114.
By combining nano-technology with fiber technology, an optical fiber doped with semiconductor nano-particles as InP is fabricated by using the modified chemical vapor deposition (MCVD) method. Proved by experiment, the fiber has excellent waveguide characteristics, and the concentration of InP is approximately 0.1~o. By using a scanning electron microscope, a stereo-scan photograph of the fiber is obtained, and based on the graph, presentations of the fiber under both magnetic and electronic fields are simulated, the effective core area Aeff≈ 10μm^2 is calculated, and so is the nonlinear index γ = 10.53 W^-1/Km of the fiber. This research leads a new method of high nonlinearity fiber fabrication.  相似文献   
115.
Zn1-xMgxO (x = 0, 0.18) thin films were fabricated on the copper substrates by radiofrequency magnetron sputtering using the high pure argon as a sputtering gas. The Zn1-xMgxO films were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and galvanostatic tests. The electrochemical test showed an improved electrochemical performance of Zn0.82EMg0.18O thin film as an anode material for lithium ion batteries.  相似文献   
116.
Three kinds of Ni-P electroless coatings were prepared in nickel sulphate solution at different pH values of 4.5,5.5 and 6.5 with the purpose of ascertaining the influence of pH value on microstructure,internal stress statue and thermal stability of the coatings.Laser curvature(LC) method was used to measure the residual stress level in the coatings.Scanning electronic microscopy(SEM) and transmission electronic microscopy with energy dispersive spectrum(TEM/EDS) were used to examine the surface morpholo...  相似文献   
117.
This article presents a facile approach to preparation of polystyrene/silver (PS/Ag) asymmetric hybrid par- ticles. In this method, polystyrene/polyglycidyl methacrylate (PS/PGMA) Janus particles were synthesized via internal phase separation triggered by evaporation of dichloromethane (DCM) from PS/PGMA/DCM- in water emulsion droplets. Then, the Janus particles were aminated and sequentially carboxylated to obtain PS/PGMA-NH2 and PS/PGMA-COOH particles. Ag+ self-assembled on the surface of PGMA hemi- sphere of the functionalized PS/PGMA particles by coordinating with amine/carboxyl. PS/Ag asymmetric hybrid particles with 7.29 wt% of Ag were obtained by reduction of Ag+, Scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy results confirmed that Ag was asymmetrically distributed on the surface of polymer particles.  相似文献   
118.
Novel organic and inorganic hybrid photovoltaic devices were thbricated by in-situ electrochemical copolymerization of 3-methylthiophene(3MT) and bithiophene(BT) into the pores of nanostructured TiO2 sintered on fluorine-doped tin oxide(FTO) substrate. The photoactive layer was investigated by Fourier transform infrared(FTIR) spectroscopy, ultraviolet-visable(UV-Vis) spectrometer, scanning electron microscope(SEM) and cyclic voltammo- gram characterization. Device efficiency based on different molar feed ratios of 3MT and BT during electrochemical polymerization, and the effect of in-situ copolymer state(doped by electrolyte and de-doped) were measured and compared. Under the solar illumination of 100 mW/cm2(AM 1.5), an optimized device efficiency of 0.938% was obtained when the molar ratio of 3MT to BT was 500:1, polymerization time was 500 s and the system was in doped copolymer state, respectively. The mechanism of overall photovoltaic parameter improvement was discussed.  相似文献   
119.
Molecularly imprinted polymer(MIP) films for hemoglobin detection were prepared onto the Au/Cr coated surface plasmon resonance(SPR) sensor chips by the in situ electropolymerization of 3-aminophenylboronic acid(3-APBA).The formation of the films and rebinding processes of hemoglobin were monitored by in situ electrochemical-SPR(EC-SPR) spectroscopy,with allowed real-time observation of the simultaneous changes in electrochemical and optical properties of the films.Scanning electron microscopy(SEM) and atomic force microscopy(AFM)were used to characterize the surface morphologies of the MIP films.The effects of pH,ion strength,different metal ions on rebinding Hb,the specific binding and the selective recognition were investigated.The results obtained with the molecular imprinted SPR chips indicate a good adsorption of Hb in a range of 0.0005-5 mg/mL in 0.05 mol/L sodium phosphate buffer at pH=7.0.A linear calibration curve(R2=0.94) of the SPR sensor for Hb detection was obtained in a range of 0.05-5 mg/mL.The detection limit for hemoglobin by this method was 0.000435 mg/mL(S/N=3).Interference studies indicate that the MIP films have a good selectivity compared with the referenced proteins.The stability of the sensor was also established.Results indicate that the SPR sensor chip keeps 87.6% of its original response after 14 d of storage under dry and ambient conditions.  相似文献   
120.
Poly(n-alkyl acrylate) with long side groups,namely,poly(lauryl acrylate)(PLA) was synthesized by reversible addition-fragmentation chain transfer(RAFT) polymerization,and the trithioester terminal groups were converted to thiol by reducing reaction.Grafting of the obtained polymer onto nano-silica modified with 3-(methacryloxy)propyl-trimethoxysilane(SiO2-MPS) was conducted by thiol-ene ‘click chemistry'.PLA was characterized by proton nuclear magnetic resonance(1H NMR) and gel permeation chromatography(GPC).Fourier transform infrared(FTIR) spectrometry and thermogravimetric analysis(TGA) were used to demonstrate the grafting reaction,and the grafted hairy nano-silica(SiO2-g-PLA) was viewed under a transmission electron microscope(TEM).According to TGA,grafting ratio and grafting density of SiO2-g-PLA are 30.27% and 0.013 chain/nm2,respectively.The static water contact angle of SiO2-g-PLA is (80.10±2.97)°,which ensures its hydrophobicity.Dispersion experiment was carried out to confirm its dispersibility in mixed solvents,indicating its potential application in coatings or composites.  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