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991.
In this paper, we introduce a new implicit iterative algorithm for finding a common element of a countable family of continuous pseudocontractions in a uniformly smooth Banach space. We obtain some strong convergence theorems under suitable conditions. Our results extend the recent results announced by many others. 相似文献
992.
993.
Guo Ping LI Wei Ren XU Xian Jie LIN Cheng Bu LIU 《中国化学快报》2006,17(3):423-426
Nitrones are useful in the preparation of many interesting compounds such as amino aldehydes, aminosugars, aza sugars, amino acids, aminoalcohols, peptide isosteres and nucleoside analogs. Nitrones are generally prepared by the condensation reactions of c… 相似文献
994.
An LD-pumped Nd:YVO4 passively Q-switched by V:YAG and intracavity frequency doubled by LBO red pulse laser at 671 nm was presented. With 1.6 W incident pump power, average output power of 53 mW, pulse duration (FWHM) of 29.5 ns, pulse repetition rate of 37.2 kHz, peak power of 48.3 W and single-pulse energy of 1.43 μJ were obtained. The stability of pulse energy and repetition rate was better than 3% for 4 h. 相似文献
995.
996.
Xiu R Bu Donald Vanderveer Javier Santos Fu-Lian Hsu Jie Wang Kofi Bota 《Analytical sciences》2003,19(3):469-470
A nonlinear optical chromophore, 4,5-bis(4-dimethylaminophenyl)-2-(4-nitrophenyl)imidazole, was investigated by X-ray crystallography. The study focused on coplanarity among several aromatic rings, including phenyls and imidazole. Two phenyl rings with NMe2 groups are twisted by 46.39(3) degrees from each other. However, they are twisted by 23.05(5) degrees and 46.84(3) degrees from the imidazole, respectively. These unequal twists were elucidated by different conjugation pathways from the donors to the acceptor. The phenyl ring with the NO2 group is twisted by only 6.76(6) degrees from the imidazole. 相似文献
997.
Xiao Gang ZHANG Guang Ying YANG Bu Xing HAN* Xi Feng ZHANG Hai Ke YAN Center for Molecular Sciences Institute of Chemistry the Chinese Academy of Sciences Beijing 《中国化学快报》2001,(1)
Supercritical fluids (SCFs) have some unique properties1 It has been known that SCFs have very strong ability to dissolve low volatile compounds, which is the basis of SCF technology. However, the mechanism of SCFs to dissolve solutes is not very clear. Enthalpy of solution of solutes in SCFs can provide useful information for studying the mechanism. In this work, we built a calorimeter and ΔH for the dissolution of naphthalene in supercritical CO2 was determined. This kind of work wa… 相似文献
998.
Xian-feng Li Huai-tian Bu De-lu Zhao State Key Laboratory of Polymer Physics Chemistry Center for Molecular Science Institute of Chemistry Chinese Academy of Sciences Beijing China 《高分子科学》2001,(4):377-384
This paper is concerned with the numerical simulation of the transient effect of an inertialess Boger flow past aconfined circular cylinder and the comparison of predictions with particle image velocimetry (PIV) measurements given byShiang et al., Dynamic simulation based on the Oldroyd-B constitutive model was carried out using a Lagrangian-Eulerianalgorithm. The evolution of velocity field was obtained for the flow at two Deborah (De) numbers, i.e. De = 1.2 and 3.0. Atlow De, the flow reached steady state rapidly, and showed a symmetric flow regime. However, at high De, the time requiredto reach steady flow behind the cylinder increased significantly, and the distribution of the velocity field appears to beasymmetric with respect to the stagnation line. Fairly good agreement between the numerical results and the experimentalobservations is reported. It can be concluded that both the experimental measurements and the present simulations indicatethat the elasticity of the polymeric flow strongly affect the flow regime of viscoelastic flow around a confined cylinder. 相似文献
999.
1000.
Zhang Zhi Hui Bu Xian He Cao Xi Chuan Ma Shu Ying Zhu Zhi Ang Chen Yun Ti 《Transition Metal Chemistry》1997,22(5):479-482
Two new macrocyclic dioxotetraamine ligands, 1-(2-methylthiophene)-1,4,8,11-tetraazacyclotetradecane-5,7-dione (H2L1) and 1,11-bis(2-methylthiophene)-1,4,8,11-tetraazacyclotetradecane-5,7-dione (H2L2), have been synthesized and characterized. The resulting dioxocyclams readily coordinate to CuII. The CuII complex of H2L2 has been isolated as a single crystal and the structure determined by X-ray diffraction analysis. The copper atom is in a square-planar environment with four basal nitrogen atoms. The solution behaviour of the CuII complexes, CuL1 and CuL2, has been further studied by e.s.r., u.v.–vis. and cyclic voltammetric techniques. A remarkable redshift has been observed for the maximum absorption band in the electronic spectra of CuL1 or CuL2 compared with that of the unsubstituted copper species (CuL). Electrochemical studies suggest that the introduction of thiophene pendant(s) to the macrocycle destabilizes the CuIII ion compared with the unsubstituted dioxocyclam, and the reason for this is discussed. 相似文献