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11.
Monitoring of ethanol during fermentation using a microbial biosensor with enhanced selectivity 总被引:1,自引:0,他引:1
Tkac J Vostiar I Gemeiner P Sturdik E 《Bioelectrochemistry (Amsterdam, Netherlands)》2002,56(1-2):127-129
The present study is concerning the construction of ferricyanide-mediated Gluconobacter oxydans cell ethanol biosensor. The size exclusion effect of a cellulose acetate membrane was used for elimination of glucose interferences during ethanol assays in real samples. A typical response time of the biosensor was 13 s with a high sensitivity of 3.5 microA mM(-1). The microbial biosensor exhibits a very low detection limit of 0.85 microM and a wide linear range from 2 to 270 microM. The operational stability was excellent. During 8.5 h of repetitive ethanol assays, no decrease in the sensor sensitivity was observed. The biosensor was successfully used in the off-line monitoring of ethanol fermentation with a good agreement with HPLC measurements (R(2)=0.998). 相似文献
12.
Peter Graf Ekkehard Kaempf Klaus Reichlmeier Karl Bernhard 《Helvetica chimica acta》1977,60(7):2151-2154
Metabolism of Acetylenic Monocarboxylic and Dicarboxylic Acids Feeding of acetylenic monoacids with chain length of 11 to 18 C-atoms to rats led to excretion of dicarboxylic acids with retained triple bonds. 10-Octadecynoic acid led to the formation of metabolites with even and odd number of C-atoms, suggesting in addition to established ω- and β-oxidation an α-oxidative pathway. 相似文献
13.
R. Imhof Frl. E. Gssinger W. Graf W. Schnüriger H. Wehrli 《Helvetica chimica acta》1971,54(8):2775-2785
The preparation of the title compounds 11 , 37 , and 39 is described. 37 will serve as starting material for a partial synthesis of the steroidal alkaloid batrachotoxinin A ( 1 ). 相似文献
14.
Starting from 3-oxo-17β-hydroxy-Δ1-5α-androstene (2b) the preparation of 1-oxo-2-methoxy-4α-methyl-17β-hydroxy-Δ2-5α-androstene (9), a compound with the ring A structure of quassine (1) is described. The key problem of the reaction sequence is shown to be the monomethylation at C(4). 相似文献
15.
Effects of a nonzero mass for the tau neutrinov τ as well as a right-handed charged-current contribution to the τ?v τ coupling are discussed. Angular correlations of the decay products of τ+τ? ine + e ? annihilation are calculated as functions of \(m_{v_\tau } \) and the relative amount of right-handed τ?v τ coupling. 相似文献
16.
17.
Cárdenas F Caba JM Feliz M Lloyd-Williams P Giralt E 《The Journal of organic chemistry》2003,68(25):9554-9562
Aplidine (dehydrodidemnin B), a natural product with potent antitumor activity currently in multicenter phase II clinical trials, exists in DMSO as a mixture of four slowly interconverting conformations in a ratio of 47:33:13:7. NMR spectroscopy shows that these arise as a consequence of cis/trans isomerization about the NMe-Leu(7)-Pro(8) and Pro(8)-Pyr amide bonds of the molecule's side chain. Two major conformations account for 47% and 33% of the total population, a ratio of 60:40 between the two. They correspond to the cis- and trans-isomers, respectively, about the Pro(8)-Pyr amide bond. Two minor conformers arise as a consequence of similar isomerism about the Pro(8)-Pyr amide bond, but in structures in which the NMe-Leu(7)-Pro(8) amide bond is cis rather than trans. These account for approximately 13% and 7% of the total population, corresponding to a ratio of 65:35 cis/trans, respectively. Molecular dynamics simulations show that the three-dimensional structures of all four conformational isomers are similar in the macrocycle and that all are essentially unchanged with respect to the macrocycle of didemnin B. Significant differences in the conformation of the molecule's side chain are, however, observed between major and minor pairs. Analysis of hydrogen-bonding patterns shows that each major conformer exhibits a beta-turn like structure and is stabilized by hydrogen bonding between a different carbonyl group of the pyruvyl unit of the molecule's side chain and the NH of the Thr(6) residue. The minor isomers have a cis-amide bond between the NMe-Leu(7) and Pro(8) residues that obliges the side chain to adopt an extended disposition where hydrogen bonding to the macrocycle is absent. These results suggest that the ability of the molecule's side chain to adopt a beta-turn-like conformation may not be a prerequisite for biological activity in the didemnins and that conformations having an extended side-chain may play a role in the biological activity of aplidine. 相似文献
18.
Acylation of diene Fe(CO)3 complexes using the Perrier complexes RCOCl/AlCl3 in methylene chloride at 0°C gives dienone complexes in high yield. Substitution occurs only at unsubstituted terminal carbons of the diene unit. Quenching the reaction mixtures in cold aqueous ammonia gives cis dienone complexes only. Trans dienone complexes are prepared by subsequent isomerization in methanolic sodium methoxide. Formylation of diene Fe(CO)3 complexes proceeds in modest yield using dichloromethylmethyleter/AlCl3 in methylene chloride to give trans-dienal complexes. Reduction of the dienone and dienal complexes as well as those of dienols and dienoic esters with 4 : 1 AlCl3/LiAlH4 results in complete removal of the oxygen function to give trans-diene complexes in good yield. 相似文献
19.
A Review of: “Aquatic Chemistry (An Introduction Emphasizing Chemical Equilibria in Natural Waters)”
Ernest Merian 《International journal of environmental analytical chemistry》2013,93(3-4):317-318
Abstract 2nd Edition, by Prof. Dr. Werner Stumm, Swiss Federal Institute of Technology, Zurich, and Prof. Dr. James J. Morgan, California Institute of Technology, Pasadena, 780 pages (including 97 tables, 167 figures, an appendix of 8 pages “Thermodynamic Properties of Common Chemical Species in Aquatic Systems”, an author index of 10 pages, and a subject index of 14 pages), stiff paper cover, format 234 ± 161 mm, ISBN 0-471-04831-3, John Wiley & Sons, New York (1981) 相似文献
20.
Dr. Carlo Fasting Prof. Christoph A. Schalley Dr. Marcus Weber Prof. Oliver Seitz Prof. Stefan Hecht Prof. Beate Koksch Dr. Jens Dernedde Prof. Christina Graf Prof. Ernst‐Walter Knapp Prof. Rainer Haag 《Angewandte Chemie (International ed. in English)》2012,51(42):10472-10498
Multivalent interactions can be applied universally for a targeted strengthening of an interaction between different interfaces or molecules. The binding partners form cooperative, multiple receptor–ligand interactions that are based on individually weak, noncovalent bonds and are thus generally reversible. Hence, multi‐ and polyvalent interactions play a decisive role in biological systems for recognition, adhesion, and signal processes. The scientific and practical realization of this principle will be demonstrated by the development of simple artificial and theoretical models, from natural systems to functional, application‐oriented systems. In a systematic review of scaffold architectures, the underlying effects and control options will be demonstrated, and suggestions will be given for designing effective multivalent binding systems, as well as for polyvalent therapeutics. 相似文献