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141.
142.
Stereospecific conversion of 9,19-cyclo-4,4,14α-trimethyl-3β-acetoxy-5α,9β-pregnan-20-one, readily accessible from cycloartenol/cyclolaudenol, into three closely related Buxus alkaloids—buxandonine, cyclo-protobuxine-F and cycloprotobuxine-A—is described. 相似文献
143.
Debajyoti Choudhury Rahul Sinha S Arunagiri Gautam Bhattacharyya Debrupa Chakraverty Debajyoti Choudhury Amitava Datta Anindya Datta Aseskrishna Datta Amol Dighe Dilip Kumar Ghosh Anjan Giri Stephen King Anirban Kundu Rukmani Mohanta Biswarup Mukhopadhyaya Sreerup Raychaudhuri Saurabh Rindani Probir Roy DP Roy Sourov Roy AI Sanda Nita Sinha Rahul Sinha K Sridhar H Yamamoto 《Pramana》2000,55(1-2):335-345
This report summarises the work done during WHEPP-6 (Institute of Mathematical Sciences, Chennai, India, Jan 3–15, 2000) in
Working group on ‘B and collider physics’. 相似文献
144.
Iodine–ammonium acetate–mediated annealation of dimedone with aldehydes led to facile formation of spirodihydrofuran in good yields through tandem Knoevenagel–Michael iodonation and cyclodehydroiodonation reactions in a single pot. 相似文献
145.
Pabitra Kumar Kalita Susanta Kumar Borthakur Runumi Das Chandan Jyoti Choudhury 《合成通讯》2013,43(21):2444-2453
This paper describes a general method for the synthesis of homoallylic alcohols and amines by nucleophilic addition reaction of allyltributylstannane to carbonyl compounds and aldimines where iodine acts as a catalyst in H2O/acetic acid (1:1) medium. Only 10 mol% of I2 is required for various organic transformations. By using this process, various homoallylic alcohols and amines are produced in good to excellent yields. 相似文献
146.
Chandan Sahu Kaushik Sen Srimanta Pakhira Bhaskar Mondal Abhijit K. Das 《Journal of computational chemistry》2013,34(22):1907-1916
The binding properties of a series of benzenesulfonamide inhibitors (4‐substituted‐ureido‐benzenesulfonamides, UBSAs) of human carbonic anhydrase II (hCA II) enzyme with active site residues have been studied using a hybrid quantum mechanical/molecular mechanical (QM/MM) model. To account for the important docking interactions between the UBSAs ligand and hCA II enzyme, a molecular docking program AutoDock Vina is used. The molecular docking results obtained by AutoDock Vina revealed that the docked conformer has root mean square deviation value less than 1.50 Å compared to X‐ray crystal structures. The inhibitory activity of UBSA ligands against hCA II is found to be in good agreement with the experimental results. The thermodynamic parameters for inhibitor binding show that hydrogen bonding, hydrophilic, and hydrophobic interactions play a major role in explaining the diverse inhibitory range of these derivatives. Additionally, natural bond orbital analysis is performed to characterize the ligand–metal charge transfer stability. The insights gained from this study have great potential to design new hCA‐II inhibitor, 4‐[3‐(1‐p‐Tolyl‐4‐trifluoromethyl‐1H‐pyrazol‐3‐yl)‐ureido]‐benzenesulfonamide, which belongs to the family of UBSA inhibitors and shows similar type of inhibitor potency with hCA II. This work also reveals that a QM/MM model and molecular docking method are computationally feasible and accurate for studying substrate–protein inhibition. © 2013 Wiley Periodicals, Inc. 相似文献
147.
Novel epoxy-based polymer 2-bearing activated azo dye, 4-(4-sulphophenylazo)-N,N-dimethylaniline (methyl orange), moieties were synthesised by post-azo-coupling reaction of poly(hydroxy ether amine) 1 and investigated sensory responses towards amines. The reversible protonation–deprotonation chemistry of activated azobenzene moiety makes it of potential use as a colorimetric indicator for amines. 相似文献
148.
Structure, frequencies, H–H stretching frequency shifts, interaction energy, depth of the potential well and dissociation energy of the light cation–dihydrogen (M+–H2, where M = Li, Na, B, and Al) van der Waals complexes have been studied in detail using dispersion corrected double-hybrid and gradient-corrected density functional methods in conjunction with correlation consistent valence triple-ζ basis set. Equilibrium bond distance and dissociation energy agree very well with the experimental and theoretical values wherever available. The dissociation energies of Li+–H2, B+–H2, Na+–H2, and Al+–H2 van der Waals complexes calculated from the potential energy curves at mPW2PLYP-D/cc-pVTZ level are 4.83, 3.68, 2.42, and 1.25 kcal/mol, respectively, at a distances of 1.95, 2.25, 2.40, and 2.95 Å. Among all these complexes, Al+–H2 complex is comparatively less stable, as their dissociation energy as well as depth of the potential well are smaller compared to others complexes. The symmetry-adapted perturbation theory (SAPT) has been applied to quantify the nature of interactions. The SAPT results show that the contribution of dispersion and induction are significant, although electrostatic dominates. 相似文献
149.
A. BhattacharyyaS. Giri S. Majumdar 《Journal of magnetism and magnetic materials》2011,323(11):1484-1489
Magnetic properties of rare-earth intermetallics RE2Ni7 (RE=Dy, Ho) are reported. Both the samples undergo two successive magnetic transitions at Th (paramagnetic to ferromagnetic) and Tl (spin reorientation) below 100 K. The transitions are found to be second order in nature as evident from the Arrot plot analysis. Large reversible magnetocaloric effect (MCE) was observed at low temperature in the studied samples. The maximum value of the magnetic entropy change in Ho2Ni7 is found to be −12.5 J/kg K (for 0 to 50 kOe of field change) around 25 K with a high relative cooling power (RCP) of 534 J/kg. The Dy counterpart also shows moderately large values of MCE (−7.3 J/kg K) and RCP (475 J/kg) around the magnetic transition region for similar change in the magnetic field. RE2Ni7 compounds can be promising materials for magnetic refrigeration in the temperature range of helium and hydrogen liquefaction. 相似文献
150.
Using first‐principles calculations with predictive capability we show that organic molecules having negative electron affinity can be transformed to superhalogens with electron affinities far exceeding that of chlorine, once its core and ligand atoms are suitably replaced. The discovery of organic superhalogens could have significant impact in chemistry, allowing the synthesis of new materials and compounds. 相似文献