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971.
Confinement effects on the electronic structure of M‐shell atoms: A study with explicitly correlated wave functions 下载免费PDF全文
Francisco J. Gálvez Enrique Buendía Antonio Sarsa 《International journal of quantum chemistry》2017,117(19)
The ground and some excited states of Na and Mg atoms confined at the center of a spherical box with impenetrable walls are studied. Variational wave functions including dynamic correlations and configuration mixing have been obtained. Level crossings induced by confinement have been analyzed in terms of the energy of the occupied orbitals of the M shell and the weight of the different configurations. Confinement effects on the correlation energy have been studied. The parameterized optimized effective potential and the variational Monte Carlo methods have been employed. A cut off‐factor has been included to account for the hard wall confinement. 相似文献
972.
Structures,stabilities, and electronic properties of fullerene C36 with endohedral atomic Sc,Y, and La: A dispersion‐corrected DFT study 下载免费PDF全文
The M@C36 compounds form a family of small endohedral metallofullerenes. Recently, these have been detected as the smallest endohedral compounds formed with Sc, Y, and La. For the first time, these compounds are studied theoretically. Calculations obtained at the dispersion‐corrected DFT level PBE‐D3(BJ)/def2‐TZVP agree admirably with experimental results. The zero‐point energy corrected binding energies can explain the lower abundance of La@C36 in comparison with Sc@C36 and Y@C36. Their small HOMO‐LUMO gaps denote high reactivity. The bond between Y and Sc with the cage is mostly covalent. In contrast, La is located at the fullerene's center with an ionic interaction; all metals transferred charge to the cage. Furthermore, La@C36 was found in doublet state and the others preferred the quartet state. To conclude, according to the analysis of aromaticity performed by the NICS(0)iso index, the insertion of none of these metals increase the aromaticity. 相似文献
973.
974.
《Journal of computational chemistry》2017,38(11):842-853
A new hardware‐agnostic contraction algorithm for tensors of arbitrary symmetry and sparsity is presented. The algorithm is implemented as a stand‐alone open‐source code libxm . This code is also integrated with general tensor library libtensor and with the Q‐Chem quantum‐chemistry package. An overview of the algorithm, its implementation, and benchmarks are presented. Similarly to other tensor software, the algorithm exploits efficient matrix multiplication libraries and assumes that tensors are stored in a block‐tensor form. The distinguishing features of the algorithm are: (i) efficient repackaging of the individual blocks into large matrices and back, which affords efficient graphics processing unit (GPU)‐enabled calculations without modifications of higher‐level codes; (ii) fully asynchronous data transfer between disk storage and fast memory. The algorithm enables canonical all‐electron coupled‐cluster and equation‐of‐motion coupled‐cluster calculations with single and double substitutions (CCSD and EOM‐CCSD) with over 1000 basis functions on a single quad‐GPU machine. We show that the algorithm exhibits predicted theoretical scaling for canonical CCSD calculations, O (N 6), irrespective of the data size on disk. © 2017 Wiley Periodicals, Inc. 相似文献
975.
《Journal of computational chemistry》2017,38(29):2475-2480
Cerium intermetallic compounds exhibit anomalous physical properties such as heavy fermion and Kondo behaviors. Here, an ab initio study of the electronic structure, magnetic properties, and mixed valence character of Ce2Ni3Si5 using density functional theory (DFT) is presented. Two theoretical methods, including pure Perdew–Burke–Ernzerhof (PBE) and PBE + U , are used. In this study, Ce3+ and Ce4+ are considered as two different constituents in the unit cell. The formation energy calculations on the DFT level propose that Ce is in a stable mixed valence of 3.379 at 0 K. The calculated electronic structure shows that Ce2Ni3Si5 is a metallic compound with a contribution at the Fermi level from Ce 4f and Ni 3d states. With the inclusion of the effective Hubbard parameter (U eff), the five valence electrons of 5 Ce3+ ions are distributed only on Ce3+ 4f orbitals. Therefore, the occupied Ce3+ 4f band is located in the valence band (VB) while Ce4+ 4f orbitals are empty and Located at the Fermi level. The calculated magnetic moment in Ce2Ni3Si5 is only due to cerium (Ce3+) in good agreement with the experimental results. The U eff value of 5.4 eV provides a reasonable magnetic moment of 0.981 for the unpaired electron per Ce3+ ion. These results may serve as a guide for studying present mixed valence cerium‐based compounds. © 2017 Wiley Periodicals, Inc. 相似文献
976.
Electronic-speckle-pattern interferometry and moiré interferometry have been used to calculateK
1 andJ for compact tension specimens. Automated-fringe-pattern analysis enables the full-field of data to be used with the minimum
of operator intervention. Measurements are shown to be accurate to within 10 percent. TheJ-measurement procedure employed could form the basis of an automatic-fault detection system. 相似文献
977.
华南典型电子垃圾拆解区土壤中十溴联苯醚的分布特征及迁移特性 总被引:1,自引:0,他引:1
十溴联苯醚(BDE-209)是电子垃圾拆解处置地区最主要的持久性有机污染物之一。采集了华南某电子垃圾拆解处置场地及其周边村镇18个采样点的表层土壤样品和其中11个采样点垂直尺度的土壤样品,利用高效液相色谱(HPLC)分析测定了BDE-209的含量。结果表明,该区域及周边农田土壤中BDE-209的浓度范围为未检出至5.47 mg·kg~(-1),在该区域的检出率达到了90%以上,BDE-209已经从电子垃圾拆解处置场所迁移到附近及周边的农田土壤中。土壤中BDE-209的垂直分布数据显示,在0~10 cm层面相对含量最高,而在50 cm以下层面均未检出,BDE-209在土壤中的浓度随深度的增加而减少,输入强度影响BDE-209在垂直方向的迁移能力。 相似文献
978.
Yaping He Prof. Dr. Jianbin Zheng Kuangtian Li Qinglin Sheng Ningqiang Qiao 《中国化学》2010,28(12):2507-2512
A room temperature ionic liquid (IL) 1‐butyl‐3‐methylimidazolium hexafluorophosphate functionalized graphene (GE) was prepared and a hydrogen peroxide (H2O2) biosensor was fabricated by immobilizing hemoglobin (Hb) into the IL‐GE composite film. UV‐visible and Fourier transform infrared spectra of the composite film indicated that Hb retained its native structure in the film. Electrochemical investigation of the biosensor showed a pair of well‐defined, quasi‐reversible redox peaks with Epa=?0.209 V and Epc= ?0.302 V (vs. SCE) in pH 7.0 phosphate buffer solution at the scan rate of 100 mV/s. To the reduction of H2O2, the biosensor had a good linear range from 8.0×10?7 to 1.8×10?4 mol/L with a detection limit of 3.0×10?7 mol/L. The apparent Michaelis‐Menten constant KappM was estimated to be 3.4×10?5 mol/L. 相似文献
979.
980.