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排序方式: 共有749条查询结果,搜索用时 500 毫秒
741.
Sandip Saha Debabrata Biswas Partha Pratim Chakrabarty Atish Dipankar Jana Athanassios K. Boudalis Saikat Kumar Seth Tanusree Kar 《Polyhedron》2010
The reaction of ethylene diamine with Cu(NO3)2·3H2O and an excess of NaN3 (1:2:4 molar ratio) lead to the formation of copper-azido based polymer [Cu4(N3)8(en)2]n (1), which has been successfully characterized by elemental analyses, IR spectroscopy, single-crystal X-ray diffraction and variable temperature magnetic study. X-ray crystal structure determination of 1 reveals that the structure consists of 1D chains of a centrosymmetric tetranuclear copper(II)-azido cluster, connected through double azido end-to-end bridges. Variable-temperature magnetic studies (between 2 and 300 K) suggest dominant antiferromagnetic interactions in this complex, although ferromagnetic interactions have been observed in all other copper-azido based polymers produced with ethylene diamine reported so far. 相似文献
742.
743.
Mahendra Varne Vaishali Samant Dr. Jahur A. Mondal Dr. Sandip K. Nayak Dr. Hirendra N. Ghosh Dr. Dipak K. Palit Dr. 《Chemphyschem》2009,10(17):2979-2994
The dynamics of the excited states of 1‐aminofluoren‐9‐one (1AF) and 1‐(N,N‐dimethylamino)‐fluoren‐9‐one (1DMAF) are investigated by using steady‐state absorption and fluorescence as well as subpicosecond time‐resolved absorption spectroscopic techniques. Following photoexcitation of 1AF, which exists in the intramolecular hydrogen‐bonded form in aprotic solvents, the excited‐state intramolecular proton‐transfer reaction is the only relaxation process observed in the excited singlet (S1) state. However, in protic solvents, the intramolecular hydrogen bond is disrupted in the excited state and an intermolecular hydrogen bond is formed with the solvent leading to reorganization of the hydrogen‐bond network structure of the solvent. The latter takes place in the timescale of the process of solvation dynamics. In the case of 1DMAF, the main relaxation pathway for the locally excited singlet, S1(LE), or S1(ICT) state is the configurational relaxation, via nearly barrierless twisting of the dimethylamino group to form the twisted intramolecular charge‐transfer, S1(TICT), state. A crossing between the excited‐state and ground‐state potential energy curves is responsible for the fast, radiationless deactivation and nonemissive character of the S1(TICT) state in polar solvents, both aprotic and protic. However, in viscous but strong hydrogen‐bond‐donating solvents, such as ethylene glycol and glycerol, crossing between the potential energy surfaces for the ground electronic state and the hydrogen‐bonded complex formed between the S1(TICT) state and the solvent is possibly avoided and the hydrogen‐bonded complex is weakly emissive. 相似文献
744.
Dy3+ and Eu2+ activated triple phosphate NaBa0.45Sr0.55PO4 phosphors were prepared by facile combustion synthesis. Excellent emission observed when NaBa0.45Sr0.55PO4:Dy3+ and NaBa0.45Sr0.55PO4:Eu2+ excited at 348 nm and 354 nm wavelength respectively. From a powder X-ray diffraction (XRD) analysis, the formation of compound with a trigonal–hexagonal scalenohedral structure was confirmed. In the photoluminescence spectra, the NaBa0.45Sr0.55PO4:Dy3+ phosphor emits two distinctive colours: a blue band centred at 482 nm and a yellow band at 576 nm originating from Dy3+ whereas NaBa0.45Sr0.55PO4:Eu2+ emits blue colour at 470 nm. Also, surface morphology has been studied by scanning electron microscope (SEM). Phosphors exhibit a strong absorption in the range of 340–400 nm and chromatic properties indicated that present phosphor is a hopeful candidate for near ultra violet light emitting diodes (nUV LEDs). 相似文献
745.
Amol H. Kategaonkar Rajkumar U. Pokalwar Sandip A. Sadaphal Pravin V. Shinde Bapurao B. Shingate Murlidhar S. Shingare 《Heteroatom Chemistry》2009,20(7):436-441
A simple and convenient method is developed for the synthesis of new O,O‐diethyl O‐(substituted tetrazolo[1,5‐a]quinolin‐4‐yl)methyl phosphorothioates, which has been synthesized for the first time from tetrazolo[1,5‐a] quinolines via tetrazolo[1,5‐a]quinolin‐4‐ylmethanol derivatives. The structures of the all newly synthesized compounds were elucidated by analytical and spectral methods. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:436–441, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20570 相似文献
746.
Sandip Chattopadhayay Anupam Ghosh Dr. Titas Kumar Mukhopadhyay Rashmi Sharma Prof. Ayan Datta Prof. Pinaki Talukdar 《Angewandte Chemie (International ed. in English)》2023,62(46):e202313712
The structural tropology and functions of natural cation-anion symporting channels have been continuously investigated due to their crucial role in regulating various physiological functions. To understand the physiological functions of the natural symporter channels, it is vital to develop small-molecule-based biomimicking systems that can provide mechanistic insights into the ion-binding sites and the ion-translocation pathways. Herein, we report a series of bis((R)-(−)-mandelic acid)-linked 3,5-diaminobenzoic acid based self-assembled ion channels with distinctive ion transport ability. Ion transport experiment across the lipid bilayer membrane revealed that compound 1 b exhibits the highest transport activity among the series, and it has interesting selective co-transporting functions, i.e., facilitates K+/ClO4− symport. Electrophysiology experiments confirmed the formation of supramolecular ion channels with an average diameter of 6.2±1 Å and single channel conductance of 57.3±1.9 pS. Selectivity studies of channel 1 b in a bilayer lipid membrane demonstrated a permeability ratio of , , and indicating the higher selectivity of the channel towards KClO4 over KCl salt. A hexameric assembly of a trimeric rosette of 1 b was subjected to molecular dynamics simulations with different salts to understand the supramolecular channel formation and ion selectivity pattern. 相似文献
747.
Gadge Sandhya Tamboli Ashif Shinde Manish Fouad Hassan Terashima Chiaki Chauhan Ratna Gosavi Suresh 《Journal of Solid State Electrochemistry》2023,27(8):2005-2015
Journal of Solid State Electrochemistry - The industrial revolution has raised major concern of environmental pollution, due to excess release of hazardous chemical, dyes, etc. into water bodies.... 相似文献
748.
A quantum pumping protocol through which the quasiparticles of Weyl/multi-Weyl and nodal-line semimetals are subjected to a time-periodic rectangular potential well is considered. The presence of an oscillating potential of frequency ω creates equispaced Floquet side-bands with spacing . As a result, a Fano resonance is observed when the difference in the Fermi energy (i.e., the energy of the incident quasiparticle), and the energy of one of the (quasi)bound state levels of the well, coincides with the energy of an integer number of photons (each carrying energy quantum ). Using the Floquet theory and the scattering matrix approach in the zero-temperature non-adiabatic pumping limit, characteristic Fano resonance patterns are found in the transmission coefficients. The inflection points in the pumped shot noise spectra also serve as a proxy for the corresponding Fano resonances. Therefore, the pumped shot noise is also numerically evaluated. Finally, the existence of the Fano resonance points is correlated to the (quasi)bound states of the well, by explicitly calculating the bound states of the static well (which are a subset of the bound states of the driven system). Since semimetals with anisotropic dispersions are considered, all the features observed depend on the orientation of the potential well. 相似文献
749.