全文获取类型
收费全文 | 245篇 |
免费 | 7篇 |
国内免费 | 1篇 |
专业分类
化学 | 115篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 18篇 |
物理学 | 115篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 3篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 15篇 |
2012年 | 16篇 |
2011年 | 13篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 9篇 |
2007年 | 13篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 11篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有253条查询结果,搜索用时 0 毫秒
51.
52.
Optical array‐based sensors are attractive candidates for the detection of various bio‐analytes due to their convenient fabrication and measurements. For array‐based sensors, multichannel arrays are more advantageous and used frequently in many electronic sensors. But most reported optically array based sensors are constructed on a single channel array. This difficulty is mainly instigated from the overlap in optical responses. In this report we have used nano‐graphene oxide (nGO) and suitable fluorophores as sensor elements to construct a multichannel sensor array for the detection of protein analytes. By using the optimized multichannel array we are able to detect different proteins and mixtures of proteins with 100 % classification accuracy at sub‐nanomolar concentration. This modified method expedites the sensing analysis as well as minimizes the use of both analyte and sensor elements in array‐based protein sensing. We have also used this system for the single channel array‐based sensing to compare the sensitivity and the efficacy of these two systems for other applications. This work demonstrated an intrinsic trade‐off associated with these two methods which may be necessary to balance for array‐based analyte detections. 相似文献
53.
The literature on inorganic open-framework materials abounds in the synthesis and characterization of metal silicates, phosphates and carboxylates. Most of these materials have an organic amine as the template. In the last few years, it has been shown that anions such as sulfate, selenite and selenate can also be employed to obtain organically templated open-framework materials. This tutorial review provides an up-to-date survey of organically templated metal sulfates, selenites and selenates, prepared under hydrothermal conditions. The discussion includes one-, two-, and three-dimensional structures of these materials, many of which possess open architectures. The article should be useful to practitioners of inorganic and materials chemistry, besides students and teachers. The article serves to demonstrate how most oxy-anions can be used to build complex structures with metal-oxygen polyhedra. 相似文献
54.
P. Mallick D.C. Agarwal Chandana Rath D. Behera D.K. Avasthi D. Kanjilal N.C. Mishra 《Radiation Physics and Chemistry》2012,81(6):647-651
NiO thin films grown on Si (100) substrate by electron beam evaporation method and sintered at 700 °C were irradiated with 200 MeV Au15+ ions. The fcc structure of the sintered films was retained up to the highest fluence (1×1013 ions cm?2) of irradiation. However the microstructure of the pristine film underwent a considerable modification with increasing ion fluence. 200 MeV Au ion irradiation led to compressive stress generation in NiO medium. The diameter of the stressed region created by 200 MeV Au ions along the ion path was estimated from the variation of stress with ion fluence and found to be ~11.6 nm. The film surface started cracking when irradiated at and above the fluence of 3×1012 ions cm?2. Ratio of the fractal dimension of the cracked surface obtained at 200 MeV and 120 MeV (Mallick et al., 2010a) Au ions was compared with the ratio of the radii of ion tracks calculated based on Coulomb explosion and thermal spike models. This comparison indicated applicability of thermal spike model for crack formation. 相似文献
55.
SR Rout B Behera TK Maiti S Mohapatra 《Dalton transactions (Cambridge, England : 2003)》2012,41(35):10777-10783
Magnetic mesoporous amorphous calcium phosphate nanoparticles with a size of 62 nm and abundant -COOH groups on the surface have been prepared by a simple method. The particles show excellent aqueous dispersion stability in physiological pH without any deterioration in hydrodynamic size and zetapotential. By virtue of the carboxylate groups on the surface, the platinum pharmacophore cis-diaquadiamine platinum(ii), folic acid and rhodamine isothiocyanate were conjugated on these magnetic calcium phosphate nanoparticles. The cytotoxicity and internalization efficiency of these nanocarriers have been evaluated on folate receptor overexpressed HeLa cells. These drug loaded nanoagents exhibit elevated cytotoxicity and induce apoptosis in HeLa cells. 相似文献
56.
Simple one-step synthesis of highly luminescent carbon dots from orange juice: application as excellent bio-imaging agents 总被引:2,自引:0,他引:2
S Sahu B Behera TK Maiti S Mohapatra 《Chemical communications (Cambridge, England)》2012,48(70):8835-8837
Highly photoluminescent carbon dots with a PL quantum yield of 26% have been prepared in one step by hydrothermal treatment of orange juice. Due to high photostability and low toxicity these carbon dots are demonstrated as excellent probes in cellular imaging. 相似文献
57.
Using density functional theory and hybrid B3LYP exchange-correlation energy functional we have studied the structure, stability, and spectroscopic properties of singly and doubly charged anions composed of simple metal atoms (Na, Mg, Al) decorated with halogens such as Cl and pseudohalogens such as CN. Since pseudohalogens mimic the chemistry of halogen atoms, our objective is to see if pseudohalogens can also form superhalogens much as halogens do and if the critical size for a doubly charged anion depends upon the ligand. The electron affinities of MCl(n) (M = Na, Mg, Al) exceed the value of Cl for n ≥ (k + 1), where k is the normal valence of the metal atom. However, for M(CN)(n) complexes this is only true when n = k + 1. In addition, while the electron affinities and vertical detachment energies of MCl(n) complexes are close to each other, they are markedly different when Cl is replaced by pseudohalogen, CN. The origin of these anomalous results is found to be due to the large binding energy of cyanogen, (NCCN) molecule. Because of the tendency of CN molecules to dimerize, the ground state geometries of the neutral and anionic M(CN)(n) complexes are very different when their number exceed the normal valence of the metal atom. While our calculations support the conclusion of Skurski and co-workers that pseudohalogens can form the building blocks of superhalogens, we show that there is a limitation on the number of CN moieties where this is true. Equally important, we find large differences between the ground state geometries of the neutral and anionic M(CN)(n) complexes for n ≥ (k + 2) which could play an important role in interpreting future experimental data on M(CN)(n) complexes. This is because the electron affinity defined as the energy difference between the ground states of the anion and neutral can be very different from the adiabatic detachment energy defined as the energy difference between the ground state of the anion and its structurally similar neutral isomer. 相似文献
58.
The phonon response of a spin density wave superconductor (SDW-SC) is calculated. The phonon self energy due to electron-phonon interaction, which involves the electronic density response function, is evaluated explicitly for the coexistent SDW-SC state. It has a square-root singularity at a frequency corresponding to the superconducting gap 2Δ. As a consequence, the spectral density function of the SDW-phonon will show a peak at 2Δ The possibility of observing the 2Δ-peak by Raman scattering is discussed. The relevance of the results to high-temperature superconductors is pointed out. The available Raman data for YBa2Cu3O7-δare compared with the results of the calculation. 相似文献
59.
60.
Zinc oxide (ZnO) and Cu-doped ZnO (CZO) thin films were prepared on borosilicate glass substrates by spray pyrolysis technique. The X-ray diffraction study revealed that Cu doping caused a reduction in crystallite size. AFM study showed an increase in roughness with doping. This is attributed to the aggregation of particles to form clusters. From transmission electron microscopy analysis, the particle size is measured to be in the range 30–65 nm (average particle size 48 nm) for undoped ZnO, whereas it is in the range 24–56 nm (average particle size 40 nm) for CZO film. The electrical resistivity of the thin films was investigated in the presence of air as well as N2 mixed air at different temperatures in the range 30–270 °C. The change in resistivity properties was explained on the basis of conduction phenomena within the grain along with the grain boundaries as well as Cu- and N2-induced defect states. The thermal activation energy of ZnO was found to be in the range 0.04–0.7 eV and dependent on Cu doping and N2 level in air. 相似文献