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951.
Biju Basumatary Dr. R. V. Ramana Reddy Rahul Prof. Dr. Jeyaraman Sankar 《Angewandte Chemie (International ed. in English)》2018,57(18):5052-5056
An expanded porphyrinoid has been obtained by a simple ring expansion from a contracted porphyrinoid, namely corrole. Spectroscopic, structural, and computational investigations reveal peculiar π‐conjugation and geometry. The effect of extended π‐conjugation is evident from perturbed redox behavior and photophysical properties. Owing to the strong diatropic ring current of the corrole and cross‐conjugation, the molecule exhibits a non‐aromatic nature for the expanded π‐circuit, as evident from NMR studies. 相似文献
952.
Boron trifluoride–etherate (BF3·OEt2) in 2,2,2‐trifluoroethanol (TFE) was found to be a highly efficient promoter system for the intramolecular alkyne–aldehyde metathesis of o-(3-arylpropargyloxy)benzaldehydes. The reaction produces the corresponding 3-aroyl-2H-chromenes in excellent yields under metal-free conditions. 相似文献
953.
Gauri Sankar Datta Rahul Mukerjee 《Annals of the Institute of Statistical Mathematics》2003,55(1):1-6
In a Bayesian setup, we consider the problem of predicting a dependent variable given an independent variable and past observations
on the two variables. An asymptotic formula for the relevant posterior predictive density is worked out. Considering posterior
quantiles and highest predictive density regions, we then characterize priors that ensure approximate frequentist validity
of Bayesian prediction in the above setting. Application to regression models is also discussed. 相似文献
954.
A detailed theoretical study of the phonon and thermal properties of achiral single wall carbon nanotubes has been carried out using force constant model considering up to third nearest-neighbor interactions. We have calculated the phonon dispersions, density of states, radial breathing modes (RBM) and the specific heats for various zigzag and armchair nanotubes, with radii ranging from 2.8 Å to 11.0 Å. A comparative study of phonon spectrum with measured Raman data reveals that the number of Raman active modes for a tube does not depend on the number of atoms present in the unit cell but on its chirality. Calculated phonon modes at the zone center more or less accurately predicted the Raman active modes. The radial breathing mode is of particular interest as for a specific radius of a nanotube it is found to be independent of its chirality. We have also calculated the variation of RBM and G-band modes for tubes of different radii. RBM shows an inverse dependence on the radius of the tube. Finally, the values of specific heat are calculated for various nanotubes at room temperature and it was found that the specific heat shows an exponential dependence on the diameter of the tube. 相似文献
955.
Construction of modified inorganic mineral with controlled mineralization analogues of those produced by nature is now of
current interest for understanding the mechanism of thein vivo biomineralization processes, as well as looking for fresh industrial and technological applications. Low-molecular-weight
chiral poly-carboxylate ligands derived from naturally occurring L-α-amino acids have been used as model systems to study
the effect of molecular properties on crystal growth modification. 相似文献
956.
Properties of steady state ion sheath formed in front of a negatively biased metal plate under the influence of negative ions
have been investigated in collisionless argon/SF6 plasma. This experiment is carried out at a fixed discharge voltage and fixed filament heating power. In this experiment,
the decrement in plasma pre-sheath potential drop as well as positive ion drift velocity toward the plate is experimentally
recorded in the presence of negative ions. It is also found that the plasma positive ion density and plasma electron temperature
decrease in the presence of negative ions. These factors attribute to the decrease of ion current toward the plate. Hence
the usual ion sheath expands.
Article presented at the International Conference on the Frontiers of Plasma Physics and Technology, 9–14 December 2002, Bangalore,
India. 相似文献
957.
meso-Tetra (2′- and 3′-thienyl)porphyrins and their Zn(II)-complexes were examined by steady-state fluorescence measurements. These
molecules exhibit significant bathochromic shift in their emission bands with decreased quantum yields relative to their correspondingmeso-tetraphenylporphyrin derivatives. The crystal structure of 5,10,15,20-tetrakis(3′-thienyl)porphinato zinc(II) shows planar and nonplanar stereochemical features of the macrocycle. One of the macrocycle
shows nearly planar while the other exhibited predominantly saddle-shaped geometry. The extent of displacement of the Β-pyrrole
carbons in the nonplanar (saddle) conformation is as high as ± 0·422 ?. 相似文献
958.
Vellaisamy P. Sankar S. Taniguchi M. 《Methodology and Computing in Applied Probability》2003,5(1):85-108
We consider the problem of designing single and the double sampling plans for monitoring dependent production processes. Based on simulated samples from the process, Nelson proposed a new approach of estimating the characteristics of single sampling plans and, using these estimates, designing optimal plans. In this paper, we extend his approach to the design of optimal double sampling plans. We first propose a simple methodology for obtaining the unbiased estimators of various characteristics of single and double sampling plans. This is achieved by defining the various characteristics of sampling plans as explicit random variables. Some of the important properties of the double sampling plans are established. Using these results, an efficient algorithm is developed to obtain optimal double sampling plans. A comparison with a crude search shows that our algorithm leads to about 90% savings, on the average, in computational timings. The procedure is also explained through a suitable example for the ARMA(1,1) model. It is observed, for instance, that an optimal double sampling plan leads to about 23% reduction in average sample number, compared to an optimal single sampling plan. Tables for choosing the optimal plans for certain auto regressive moving average processes at some practically useful values of acceptable quality level and rejectable quality level are also presented. 相似文献
959.
Birinchi Kumar Das Sanchay Jyoti Bora Monideepa Chakrabortty Laksheswar Kalita Rajesh Chakrabarty Ramakanta Barman 《Journal of Chemical Sciences》2006,118(6):487-494
Molecules in metal isonicotinate tetrahydrates, M(NC5H4-p-CO2)2.4H2O with M = Mn, Fe, Co, Ni, Cu, Zn, consisting of the hexacoordinate complexestrans-[M(NC5H4-p-CO2)(OH2)4], participate in exhaustive hydrogen-bond formation among themselves to lead to a robust 3D supramolecular network in the
solid state. Solid-state diffuse reflectance UV-Vis-NIR spectra of the complexes have been assigned to ligand field and charge
transfer transitions. Sharp weight loss due to dehydration, as shown by TGA of Cu(NC5H4-p-CO2)2.4H2O, suggests the suitability of this complex for the gravimetric estimation of copper. 相似文献
960.
Cracks are one of the common defects in structural components that may ultimately lead to failure of structures if not detected. Generally, most of the vibration based crack detection methods transform measured vibration responses from time-domain into frequency-domain using Fourier or wavelet transform for damage detection. However, it would be more convenient if the vibration responses could be analysed in their original time-domain. Therefore, a practical method based on probability distribution function is proposed which performs all the data processing in time-domain for the purpose of crack detection in beam-like structures. The application of the proposed method to both numerical and experimental examples and their results are presented. 相似文献