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691.
We argue that a pseudo-one-dimensional electron gas is magnetized when a voltage bias is applied with the Fermi level tuned to be in the energy gap generated by a spin-orbit interaction. The magnetization is an indication of spin-carrying currents due to the spin-orbit interaction. The origin of the magnetization, however, is essentially different from the “spin accumulation” in two-dimensional systems with spin-orbit interactions. 相似文献
692.
Dielectric properties and substitution preference of yttrium doped barium zirconium titanate ceramics 总被引:1,自引:0,他引:1
The dielectric properties of Ba(Zr0.25Ti0.75)O3+xY 2O3 ceramics are investigated. We believe that, integrating with the lattice parameters, there is an alternation of substitution preference of yttrium ions for the host cations in perovskite lattice that is responsible for the Curie point. The Tc rises with the increase of Y 3+ doping when the doping content is less than 0.05 at%, owing to the replacement of Y 3+ ions for Ba2+ ions at the A-site; when the Y 3+ content is more than 0.05 at%, Y 3+ ions tend to occupy the B-site in perovskite lattice, causing a drop of Tc. Owing to the modifications of Y 3+ doping, the loss tangent of BZT ceramics is depressed remarkably, making it a superior candidate to replace widely used lead-contained ceramics. 相似文献
693.
Synthesis and magnetic properties of Mn doped ZnO nanowires 总被引:1,自引:0,他引:1
Sasanka Deka 《Solid State Communications》2007,142(4):190-194
Mn doped ZnO nanowires have been synthesized using a simple autocombustion method. The as-synthesized Mn doped ZnO nanowires were characterized by X-ray diffraction and transmission electron microscopy. An increase in the hexagonal lattice parameters of ZnO is observed on increasing the Mn concentration. Optical absorption studies show an increment in the band gap with increasing Mn content, and also give evidence for the presence of Mn2+ ions in tetrahedral sites. All Zn1−xMnxO (0≤x≤0.25) samples are paramagnetic at room temperature. However, a large increase in the magnetization is observed below 50 K. This behavior, along with the negative value of the Weiss constant obtained from the linear fit to the susceptibility data below room temperature, indicate ferrimagnetic behavior. The origin of ferrimagnetism is likely to be either the intrinsic characteristics of the Mn doped samples, or due to some spinel-type impurity phases present in the samples that could not be detected. 相似文献
694.
F. Russo G. Carapella V. Granata N. Martucciello G. Costabile 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(1):61-66
The magnetoresistance of several Ferromagnet/Normal
metal/Ferromagnet spin-valve type structures has been investigated using Al
as normal spacer layer. A magnetoresistance ratio up to 4.1% at room
temperature and 5.7% at 0.3 K is found for the sandwich with both Co
layers, while slightly lower signals are found for the structures involving
CoFe and NiFe layers. The magnetoresistance dependence for Co/Al/Co,
Co/Al/CoFe and Co/Al/NiFe on the spacer layer thickness exhibits the
familiar non monotonic behaviour with second peak slightly larger than the
one reported for Cu based pseudo spin valves. At cryogenic temperatures,
preliminary results on the onset of spin switch effects in Co/Al/Co and the
full spin switch effect in Co/Nb/Co are also reported here. 相似文献
695.
Lamellar systems are self-assemblies of surfactant molecules forming planar bilayers separated by layers of solvent. At sufficiently
high shear rates, they are known to form spherical objects often referred to as onions. In this paper, we are concerned with the effect of shear on those multi-lamellar vesicles. We measure solvent diffusion
by nuclear magnetic resonance (NMR) using a method which is sensitive to the time dependence of mean-squared displacements.
This method, combined with NMR velocimetry, allows us to infer onion structure as a function of shear rate, identifying different
regimes in which local viscosity is related to the onion size. The role of slip is examined and the stress dependence of wall
slip velocities is determined. 相似文献
696.
设计合成了对称型菲并咪唑荧光探针PIP-ph-PIP, 并对其结构进行了表征和确认. 随着探针溶液中水体积分数的增加, 探针的聚集程度逐渐增加, 荧光强度先增强后猝灭. 荧光光谱测试结果表明, 在水相体系中探针PIP-ph-PIP能以ON-OFF-ON的方式分别对Ag+和SCN-, Cu2+和PO34 -进行连续识别, 且连续识别效果可通过裸眼比色观察, 其中对Ag+识别具有超低检出限(6.1 nmol/L). 结果表明, 探针PIP-ph-PIP可应用于活体HeLa细胞中Ag+和Cu2+的定性分析及实际水样中Ag+和Cu2+的定量检测. 相似文献
697.
The crystal structure of the title compound 1-(4-fluorophenyl) -2-hexylthio-benzo [4,5]furo[3,2-d]-1,2,4-triazolo[1,5-a]pyrimidin-5(1H) -one(C23H21FN4O2S,Mr = 436.5) has been prepared and determined by single-crystal X-ray diffraction. The crystal is of monoclinic,space group P21/n with a = 13.9854(3) ,b = 17.2678(4) ,c = 18.1828(5) ,β = 99.364(2) °,V = 4332.58(18) 3,Z = 4,Dc = 1.338,F(000) =1824,μ = 0.185 mm-1,MoKa radiation(λ = 0.71073) ,R = 0.0538 and wR = 0.1162 for 4728 observed reflections with I > 2σ(I) . X-ray diffraction analysis reveals the fused rings of benzo[4,5]furo[3,2-d]-1,2,4-triazolo[1,5-a] pyrimidin-5(1H) -one system are nearly coplanar. The crystal packing is mainly stabilized by weak intermolecular C-H···O hydrogen bond and π-π interactions. 相似文献
698.
Arivazhagan M Senthil kumar J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,82(1):228-234
The FTIR and Laser Raman spectra of 4-amino pyrazolo (3,4-d) pyrimidine have been measured in the regions 4000–400 cm−1 and 3500–100 cm−1, respectively. Utilizing the observed FTIR and Laser Raman data, a complete vibrational assignment and analysis of the fundamental modes of the title compound were carried out. The vibrational frequency which were determined experimentally are compared with those theoretically from force field calculation based on ab initio HF/6−311+G**(d,p) and standard B3LYP/6−311+G**(d,p) methods and basis set combinations for optimized geometries. The observed FTIR and Laser Raman vibrational frequencies were analysed and compared with the theoretically predicted vibrational frequencies. The assignments of bands to various normal modes of the molecules were also carried out. A detailed interpretation of the infrared and Raman spectra of 4-amino pyrazolo (3,4-d) pyrimidine [4AP(3,4-D)P] is also reported based on total energy distribution (TED). The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The theoretical FT-IR and FT-Raman spectra for the title molecule have also been constructed. 相似文献
699.
The title compound (C21H24N4O4, Mr = 396.44) has been synthesized by the func- tionalized ethyl 4-chloro-6-methyl-2-arylamino-furo[2,3-d]pyrimidine-5-carboxylates and mor- pholine. Its structure was confirmed by means of 1H NMR IR, MS and elemental analysis. The crystal structure of the title compound was determined by X-ray single-crystal diffraction. The compound crystallizes in triclinic system, space group P1, a = 7.9919(8), b = 9.9312(1), c = 12.9380(13) A, aα = 86.987(2), β = 83.604(2), γ = 89.641(2)°, V = 1019.08(18) A3, Z = 2, F(000) = 420, Dc = 1.292 g/cm3,μ = 0.091 mm-1, R = 0.0602 and wR = 0.1548 for 3943 independent (Rint = 0.0639) and 3414 observed (I 〉 2σ(I)) reflections, lntermolecular N-H…O and π-π stacking interactions contributed to the stability of the structure. The preliminary biological test indicated the title compound exhibited cytotoxicity against human lung cancer cell lines. 相似文献
700.
Qing-Shan Du Yan-Xia Shi Peng-Fei Li Zhen-Jiang Zhao Wei-Ping Zhu Xu-Hong Qian Bao-Ju Li Yu-Fang Xu 《中国化学快报》2013,24(11):967-969
The 1,2,3-thiadiazole-carboxylate moiety was reported to be an important pharmacophore of plant activators.In this study,a series of novel plant activators based on thieno[2,3-d]-1,2,3-thiadiazole-6-carboxylate were designed and synthesized and their biological activity as plant activators was studied.The structures of the novel compounds were identifed by1H NMR,19F NMR and HRMS.The in vivo bioassay showed that these novel compounds had good effcacy against seven plant diseases.Especially,compounds 1a and 1c were more potent than the commercialized plant activator BTH.Almost no fungicidal activity was observed for the active compounds in the in vitro assay,which matched the requirements as plant activators. 相似文献