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971.
Xu J Jang K Choi J Jin J Park JH Kim HJ Oh DH Ahn JR Son SU 《Chemical communications (Cambridge, England)》2012,48(50):6244-6246
Through an organometallic approach, ultrathin SnO(x)Fe(y)S(z) plates with ~2 nm single layer-thicknesses were obtained and their graphene composites showed very promising discharge capacities of up to 736 mA h g(-1) and excellent stabilities as anode materials in lithium ion batteries. 相似文献
972.
Kim JH Lee E Park JS Kataoka K Jang WD 《Chemical communications (Cambridge, England)》2012,48(30):3662-3664
Dendritic-linear block copolymers that have pH responsive poly(benzyl ether) dendrons and temperature responsive PiPrOx chains have been designed by copper-mediated click reactions. These copolymers exhibit sharp thermal transitions with a wide range of pH-dependent thermal transition temperatures. 相似文献
973.
Pang SC Hyun H Lee S Jang D Lee MJ Kang SH Ahn KH 《Chemical communications (Cambridge, England)》2012,48(31):3745-3747
A new diarylethene-derived photochromic compound, with little cytotoxicity, plasma membrane-permeability, and efficient photoswitchability in cells upon alternative UV and visible light irradiation, was synthesized and applied to live cell imaging. 相似文献
974.
Jang YJ Syu SE Jhang YW Lee YT Lee CJ Chen KW Das U Lin W 《Molecules (Basel, Switzerland)》2012,17(3):2529-2541
A new highly efficient three-component reaction of alkyl acrylate, aldehyde and dialkyl malonate using ethyl diphenylphosphine as organocatalyst has been described. Various highly functional compounds bearing hydroxyl groups and the ester functions can be easily prepared in moderate to good yields according to our one-step procedure. The reactions are believed to proceed via Morita-Baylis-Hillman reactions of alkyl acrylate and aldehydes, followed by the Michael addition reactions of dialkyl malonates. Our reactions indicated that the intermediate species formed in the phosphine-catalyzed MBH reaction are an effective organic base to catalyze the Michael addition reactions of dialkyl malonates to the preformed MBH adducts. 相似文献
975.
Eun Hye Na Jung-Hoon Lee Suk-Jin Ahn Kun-Pyo Hong Yang Mo Koo Hyun Myung Jang 《Journal of magnetism and magnetic materials》2012
We have studied magnetic structure and properties of Ga-substituted Pb-hexaferrites having the stoichiometry of PbFe12−xGaxO19 with x=6 (i.e., Fe:Ga=1:1). According to the neutron diffraction results, this compound is characterized by a collinear spin structure below its Curie temperature (∼325 K). Analysis of the neutron diffraction patterns further indicates that the magnetic-moment direction of Fe3+ ions located at the octahedral 2a sublattice is downward while that of the unsubstituted PbFe12O19 is upward at room temperature. With decreasing temperature, the Fe3+ magnetic moment at the octahedral 2a sublattice undergoes a reorientation to the upward direction while that of the unsubstituted PbFe12O19 remains upward down to 5 K. This selective local spin reversal at the 2a sublattice of PbFe6Ga6O19 was attributed to the weakening of the superexchange interaction between the octahedral 2a site and the tetrahedral 4fIV site upon the preferential substitution of Ga ions for Fe ions at these two neighboring sites. Comparison of the neutron diffraction results with dc magnetization responses and ac susceptibilities further indicates that the paramagnetic–ferrimagnetic transition at ∼325 K (Tc) is followed by the local spin reversal at lower temperatures. 相似文献
976.
Nam TS Choi SH Rah SY Kim SY Jang W Im MJ Kwon HJ Kim UH 《Experimental & molecular medicine》2006,38(6):718-726
ADP-ribosyl cyclase (ADPR-cyclase) produces a Ca2+-mobilizing second messenger, cyclic ADP- ribose (cADPR), from beta-NAD+. A prototype of mammalian ADPR-cyclases is a lymphocyte antigen CD38. Accumulating evidence indicates that ADPR-cyclases other than CD38 are expressed in various cells and organs. In this study, we discovered a small molecule inhibitor of kidney ADPR-cyclase. This compound inhibited kidney ADPR-cyclase activity but not CD38, spleen, heart or brain ADPR-cyclase activity in vitro. Characterization of the compound in a cell-based system revealed that an extracellular calcium-sensing receptor (CaSR)- mediated cADPR production and a later long-lasting increase in intracellular Ca2+ concentration ([Ca2+]i) in mouse mesangial cells were inhibited by the pre-treatment with this compound. In contrast, the compound did not block CD3/TCR-induced cADPR production and the increase of [Ca2+]i in Jurkat T cells, which express CD38 exclusively. The long-lasting Ca2+ signal generated by both receptors was inhibited by pre-treatment with an antagonistic cADPR derivative, 8-Br-cADPR, indicating that the Ca2+ signal is mediated by the ADPR-cyclase metabolite, cADPR. Moreover, among structurally similar compounds tested, the compound inhibited most potently the cADPR production and Ca2+ signal induced by CaSR. These findings provide evidence for existence of a distinct ADPR-cyclase in the kidney and basis for the development of tissue specific inhibitors. 相似文献
977.
A branching DOS strategy for an unbiased natural product-like library with embedded privileged benzopyran motif was established to provide complexity and diversity of resulting heterocycles with desired drug-likeness. The importance of skeletal diversity conducted on a privileged substructure was demonstrated through the biological evaluation of a small molecule library representing 22 unique core skeletons via in vitro cytotoxicity assay. 相似文献
978.
A novel method of preparing thermally stable zirconia-based mesoporous materials was developed. The zirconia-based mesoporous materials of 2D-hexagonal structure were prepared using zirconium sulfate as the zirconium precursor and cetyltrimethylammonium (CTMA) as the pore-directing agent with the aid of salt in the synthesis solution to reduce the sulfate content in the final product and significantly improve the crystallographic ordering. Post-treatment of the mesoporous material with NaCl solution and lowering the ramping rate to less than 0.2 degrees C/min during the calcination process, however, were the key steps to hinder the growth of the dense zirconia phase and to retain the ordered mesostructure up to 600 degrees C. It was found that a portion of the surfactant (8.9-17.4 wt %) and sulfate ions (0.5-1.2 wt %) were removed during the post-treatment, which prevented the remaining sulfate groups from being reduced by the hydrogen-rich surfactant during the calcination process as confirmed by sulfur K-edge X-ray absorption near edge structure (XANES) and infrared spectroscopy. The maintenance of sulfur in the sulfate state seemed to be important in stabilizing the mesoporous structure of zirconia materials. The mesoporous zirconia materials after extraction with NaCl solution three times and calcination at 550-600 degrees C had the composition ZrO(2-x)(SO4)x with x = 0.10-0.27. The material possesses high surface area (approximately 200 m2/g), large pore volume (approximately 0.10 cm3/g), and wormlike mesopores. In comparison with the mesoporous zirconia materials stabilized by chemical treatment, the present route was simpler and more environmentally friendly and resulted in mesoporous zirconia materials of better thermal stability. 相似文献
979.
Fabrication of nanorattles with passive shell 总被引:1,自引:0,他引:1
Chen HM Liu RS Asakura K Lee JF Jang LY Hu SF 《The journal of physical chemistry. B》2006,110(39):19162-19167
This investigation describes the formation of a metal nanorattle with a pure metal shell by varying experimental parameters. The galvanic replacement reaction between silver and chloroauric acid was adopted to prepare hollow metal nanoparticles. This approach is extended to produce nanorattles of Au cores and Au shells by starting with Au(core)Ag(shell) nanoparticles as templates. The effect of temperature on the nanostructure of the final product is also considered. The composition of the shell in nanorattles can be controlled by varying the reaction temperature (to form pure gold or gold-silver alloy, for example). X-ray absorption fine structure spectroscopy is conducted to elucidate the fine structure of these nanoparticles. Partial alloying between the Au core and the Ag shell is observed by extended X-ray absorption fine structure (EXAFS). 相似文献
980.
Yun Jung Jang Byung-Sik Moon Min Sun Park Ji Young Kwon Yeo Joon Yoon Juyoung Yoon 《Tetrahedron letters》2006,47(16):2707-2710
New cavitand derivatives (1, 2) bearing four coumarin groups were synthesized, and the binding properties of these cavitands towards metal ions were examined through their fluorescent changes. Cavitand 1 effectively recognized the Cu2+ ions among the metal ions examined. The recognition of cavitand 1-Cu2+ with dicarboxlyates is also described. 相似文献