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821.
基于最近实验工作的结果(2010 Nat.Phys.6 265)即Danzl等在五能级M型级联系统中分别利用连续型和四光子型受激拉曼绝热通道(stimulated Raman adiabatic passage,STIRAP)实现了将Feshbach态上弱束缚的Cs2有效转移到其振转基态,本文理论研究了两种STIRAP方案实施的基本条件,解析推导系统的准暗态、绝热参数的具体形式并分析其存在的必要性,详细讨论布居转移效率对相关参量的依赖关系.通过比较激光脉冲的时序、中间能级的失谐量和自发辐射率、光场脉冲的幅值等诸多参量的不同影响,讨论方案各自的优缺点,找到了参量优化的方法以实现最高效的粒子布居数转移.与前人的实验结果相比,本文研究表明,实验观测值(约0.60)均低于理论预估最佳值(约0.97)的主要原因是受限于激发态能级的自发辐射率过大.该理论方案还可用于制备量子纠缠态,在量子逻辑门操控、量子信息传输等领域都有潜在的应用. 相似文献
822.
介绍贝壳的艺术美和它带给人类的创造灵感,介绍贝壳在材料强韧化方面所创造的力学奇迹:利用95%左右的原始低强度碳酸钙,加上少量蛋白质和多糖有机胶,建造了精巧的分级嵌套微结构,使韧性比组分材料提高了3个数量级,成为超级生物材料.接下来将继续介绍分级嵌套微结构强韧化的力学机制、连接不同尺度微结构的矿物桥和人类在贝壳仿生方面的进展. 相似文献
823.
采用非线性偏振旋转锁模,构建了一种全正色散掺Yb3+光纤环形激光器.在该激光腔内采用了10 nm带宽的光纤滤波器提供附加的自振幅调制.通过改变滤波器在腔内的位置,实验证明了滤波器位置对高啁啾脉冲的整形过程起到重要的作用.在320 mW的抽运功率下,最终获得平均功率为922 mW,脉冲重复频率为266 MHz,脉冲宽度为62 ps的稳定脉冲输出,单脉冲能量达35 nJ的优化结果.通过数值模拟与实验结果的验证表明,两者相符很好.
关键词:
锁模光纤激光器
全正色散
滤波效应
高啁啾脉冲 相似文献
824.
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826.
Alver B Back BB Baker MD Ballintijn M Barton DS Betts RR Bindel R Busza W Chai Z Chetluru V García E Gburek T Gulbrandsen K Hamblen J Harnarine I Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Kane JL Kulinich P Kuo CM Li W Lin WT Loizides C Manly S Mignerey AC Nouicer R Olszewski A Pak R Reed C Richardson E Roland C Roland G Sagerer J Sedykh I Smith CE Stankiewicz MA Steinberg P Stephans GS Sukhanov A Szostak A Tonjes MB Trzupek A van Nieuwenhuizen GJ Vaurynovich SS Verdier R 《Physical review letters》2006,96(21):212301
We present transverse momentum distributions of charged hadrons produced in Cu + Cu collisions at square root of SNN = 62.4 and 200 GeV. The spectra are measured for transverse momenta of 0.25 < pT < 5.0 GeV/c at square root of SNN = 62.4 GeV and 0.25 < pT < 7.0 GeV/c at square root of SNN = 200 GeV, in a pseudorapidity range of 0.2 < eta < 1.4. The nuclear modification factor R(AA) is calculated relative to p + p data at both collision energies as a function of collision centrality. At a given collision energy and fractional cross section, R(AA) is observed to be systematically larger in Cu + Cu collisions compared to Au + Au. However, for the same number of participating nucleons, R(AA) is essentially the same in both systems over the measured range of pT, in spite of the significantly different geometries of the Cu + Cu and Au + Au systems. 相似文献
827.
Kulatilaka WD Chai N Naik SV Laurendeau NM Lucht RP Kuehner JP Roy S Gord JR 《Optics letters》2006,31(22):3357-3359
We have measured nitric oxide (NO) concentrations in flames by using electronic-resonance-enhanced coherent anti-Stokes Raman spectroscopy (ERE-CARS). Visible pump and Stokes beams were tuned to a Q-branch vibrational Raman resonance of NO. A UV probe beam was tuned into resonance with specific rotational transitions in the (v"=1,v'=0) vibrational band in the A(2)Sigma(+)-X(2)Pi electronic transition, thus providing a substantial electronic-resonance enhancement of the resulting CARS signal. NO concentrations were measured at levels down to 50 parts in 10(6) in H(2)/air flames at atmospheric pressure. NO was also detected in heavily sooting C(2)H(2)/air flames at atmospheric pressure with minimal background interference. 相似文献
828.
Wen-Xian Li Yu-Shan Zheng Xiao-Jun Sun Xiao-Yan Shi Wen-Juan Chai Tie Ren 《Journal of fluorescence》2010,20(1):235-241
A ligand with double sulfinyl groups, naphthyl-naphthalinesulphonylpropyl sulfoxide(dinaphthyl disulfoxide, L), was synthesized
by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity,
coordination titration analysis, IR, TG-DTA, 1HNMR and UV spectra. The composition of these complexes, were RE2(ClO4)6·(L)5·nH2O (RE = La, Nd, Eu, Tb, Yb, n = 2 ∼ 6, L = C10H7SOC3H6SOC10H7). The fluorescent spectra illustrated that the Eu (III) complex had an excellent luminescence. It was supposed that the ligand
was benefited for transferring the energy from ligand to the excitation state energy level (5D0) of Eu (III). The Tb (III) complex displayed weak luminescence, which attributed to low energy transferring efficiency between
the average triplet state energy level of ligand and the excited state (5D4) of Tb (III). So the Eu (III) complex displayed a good antenna effect for luminescence. The phosphorescence spectra and the
relationship between fluorescence lifetime and fluorescence intensity were also discussed. 相似文献
829.
Toxicity of zinc oxide nanoparticles to zebrafish embryo: a physicochemical study of toxicity mechanism 总被引:1,自引:0,他引:1
Wei Bai Zhiyong Zhang Wenjing Tian Xiao He Yuhui Ma Yuliang Zhao Zhifang Chai 《Journal of nanoparticle research》2010,12(5):1645-1654
The biological impact of engineered nanomaterials released into the aquatic environment is a major concern. In this work, the properties of ZnO nanoparticles (nano-ZnO, 30 nm) were characterized in a water suspension (E3 medium), and a zebrafish 96-h post fertilization (hpf) embryo–larval test was performed to assess the toxicity of nano-ZnO suspension. Nano-ZnO was found to readily form aggregates with different sizes; small aggregates (142.4–517.7 nm) were still suspended in E3 medium, but large aggregates (>1 μm) quickly deposited on the bottom of 24-well plates; nano-ZnO was partially dissolved to Zn species (Zn(dis)) in E3 medium. In the nano-ZnO suspension, small aggregates, Zn(dis), and large aggregates might jointly exert influence on the development of zebrafish embryos. The embryo toxicity test revealed that nano-ZnO killed zebrafish embryos (50 and 100 mg/L), retarded the embryo hatching (1–25 mg/L), reduced the body length of larvae, and caused tail malformation after the 96 hpf exposure. Zn(dis) only partially contributed to the toxicity of nano-ZnO. This research highlights the need to further investigate the ecotoxicity of nano-ZnO in the water environment. 相似文献
830.
Journal of Solid State Electrochemistry - SnO2/Fe2O3 composites with a novel heterojunction nanostructure are successfully prepared via a facile two-step hydrothermal method. Fe2O3 nanoparticles... 相似文献