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991.
Akira Kitani Masanori Kaya Syo-Ichi Tsujioka Kazuo Sasaki 《Journal of polymer science. Part A, Polymer chemistry》1988,26(6):1531-1539
Flexible polyaniline having excellent mechanical properties (e.g., elongation at break = 41% and tensile strength = 1.8 kg cm?2) was prepared by electrochemical reduction of ordinary polyaniline in organic solvents. The flexibility is directly related with the polymer morphology which was definitely affected by the nature of electrolyte anion. Perchlorate or tetrafluoroborate anion were found suitable to obtain flexible polyaniline. At the same time, it is essential that the polymer so prepared should be reduced (undoped) in some suitable organic solvents before making a flexible free standing film. 相似文献
992.
Rafael E. Vasquez Masaya Hono Akira Kitani Kazuo Sasaki 《Journal of Electroanalytical Chemistry》1985,196(2):397-415
The contribution of the heterogeneous (involving non-adsorbed solution species) and surface path (involving adsorbed species) to the electrode processes of aromatic nitro compounds has been studied as a function of the surface conditions of glassy carbon (GC-20) by linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The influence of adsorption was negligible at the freshly polished electrodes. Oxidative electrochemical pretreatment led to the formation of active sites at which the adsorption of the reactant resulted in enhanced electron-transfer rates. The nature of the adsorption process and the characteristics of the electrode reaction in the adsorbed state were studied in detail for p-nitrotoluene. The adsorption followed the Frumkin isotherm with an interaction parameter of 1.2, indicating moderate attractive interactions between the adsorbed molecules. The rate constant for the adsorbed species was of the order of 105, higher than the apparent heterogeneous rate constant of p-nitrotoluene in the solution phase. The magnitude of the potential shift and the strength of adsorption varied with the relative position and electron-withdrawing power of the substituent in the aromatic ring of nitrobenzene. Free radical coupling was selectively catalysed at electrochemically pretreated electrodes. 相似文献
993.
Nerol is cyclized to terpinyl chloride or bromide in the presence of TiX4-PhNHMe (1:1) complex in dichloromethane at ?23 °C, while cyclization of ()-allylic alcohols CH2=CR-CH2CH2CMe=CHCH2OH (R = H, Me, Cl) produces seven-membered ring products in fair yields. 相似文献
994.
Me2AlSPh or Me2AlSeMe adds to α,β-unsaturated carbonyl compounds in 1,4-fashion. The resulting aluminium enolates react with aldehydes effectively to afford the adducts of the title anion after formal PhSH (or MeSeH)-elimination. 相似文献
995.
William R. Dolbier Jr. Samia Aït-Mohand Tatiana A. Sergeeva Akira Mitani Rolf W. Winter 《Journal of fluorine chemistry》2006,127(10):1302-1310
Both SF5Cl and SF5Br undergo smooth, high yield addition to alkenes and alkynes under the mild free radical chain reaction conditions of triethylborane initiation at low temperature, although the SF5Br chemistry is somewhat limited by its competing high electrophilic reactivity with electron rich alkenes. The SF5Cl addition reaction is relatively insensitive to a wide variety of non-allylic functionalities. 相似文献
996.
Akira Miyashita Mayumi Ohyoshi Hiroaki Shitara Hiroyuki Nohira 《Journal of organometallic chemistry》1980,338(1):103-111
Bis(phosphine)-3,3-dimethylnickela- and palladacyclobutanes have been prepared by intramolecular C-H insertion reaction of the corresponding dineopentyl metal complexes. Nickelacyclobutane complexes decompose when heated thereby undergoing competitive carbon-carbon bond cleavage to give isobutene and ethylene, with reductive elimination affording 1,1-dimethylcyclopropane and skeletal isomeri-zation of the metallacyclic ring yielding 3-methyl-1-butene, whereas the palladium analog gave no significant amounts of CC bond cleavage products.Added phos-phine was seen to have an effect on CC bond scission of nickelacyclobutane complexes. Nickelacyclobutane complexes in solution are thought to be in equilibrium with olefin-coordinated nickel-carbene complex on the basis of available experimental evidence from hydrogenolysis, carbene-trap reactions with olefins and reaction with carbon monoxide 相似文献
997.
Youichi Nakayama Takayuki Takahagi Fusami Soeda Kenji Hatada Shoji Nagaoka Jirou Suzuki Akira Ishitani 《Journal of polymer science. Part A, Polymer chemistry》1988,26(2):559-572
Gas phase chemical modification (GCM) is found to be more preferable as a pretreatment for the XPS surface analysis of polymer materials than the conventional liquid phase treatment because it can circumvent problems such as solvent contamination and swelling. We have tried the quantification of the surface composition successfully by estimating the yield of the reaction from model samples. GCM was then applied to correlate the surface composition of NH3 plasma-treated polystyrene films with their cell-affinity. The amount of primary-amine and that of carboxylic acid were directly determined by GCM. Although the amount of primary-amine, 15–20% of total nitrogen, did not depend on the treatment intensity, the total amine content for the treated samples increased with the plasma treatment intensity. The quantity of carboxylic acid generated was found to be very small. All treated samples had better cell-affinity than the control. The sample N2 (of medium treatment) showed the best cell-affinity. The most strongly treated sample N3, with larger amine content than N2, showed worse cell-affinity because of the interference by the sputtered SiO2 on the surface. 相似文献
998.
Yoshinori Tominaga Yasumasa Honkawa Mayumi Hara Akira Hosomi 《Journal of heterocyclic chemistry》1990,27(3):775-783
The cyclization of 5-amino-3-methylthiopyrazole-4-carbonitriles or 4-carboxamides 3a-j , which were prepared by the reaction of ketene dithioacetals 1a,b [1a : bis(methylthiomethylenemalononitrile; 1b : bis(methylthio)methylenecyanoacetamide] with hydrazines (hydrazine hydrate, phenylhydrazine, p-chlorophenylhydrazine, p-nitrophenylhydrazine), with formamide or carbon disulfide proceeded to give the corresponding 4-amino- or 4-hydroxy-3-methylthiopyrazolo[3,4-d]pyrimidines 6a-h in good yields. 3-Aminopyrazolo[3,4-d]pyrimidine derivatives 6i-1 were also obtained by the application of the cyclization reaction of 3,5-diaminopyrazoles with formamide. 相似文献
999.
Otaka A Katagiri F Kinoshita T Odagaki Y Oishi S Tamamura H Hamanaka N Fujii N 《The Journal of organic chemistry》2002,67(17):6152-6161
Proline dipeptides (Xaa-Pro) exist as an equilibrium mixture of cis- and trans-rotamers, which depends on the energy barriers for imide isomerization. This conformation mixture contributes to both structure and function of proline-containing peptides and proteins. Structural motifs resembling these cis- or trans-conformers have served as useful tools for elucidating contributions of proline residues in the physicochemical and biological profiles of structures which contain them. Among such motifs are alkene dipeptide isosteres which mimic cis- or trans-imide using (Z)- or (E)-alkene, respectively. In this report, the first regio- and stereoselective syntheses of (E)-alkene dipeptide isosteres (20, 31, and 35) corresponding to trans-proline dipeptides are described. Key to the synthesis of these mimetics is the anti-S(N)2' reaction of vinyl aziridines such as 15 or vinyl oxazolidinones such as 28 and 32 with organocopper reagents "RCu" (R = CH(2)SiMe(2)(Oi-Pr)). Reaction of cis-vinylaziridine 15 derived from L-serine with organocopper reagent gave a precursor of the trans-L-Ser-D-Pro type alkene isosteres 20, accompanied by an S(N)2 side product. One limitation with the use of such aziridine-mediated methodology is formation of the corresponding trans-aziridine 22, which leads to L-L type isosteres, that is unstable and obtainable only in low yield. On the other hand, both isomers of oxazolidinone derivatives can be easily obtained from N-Boc-protected amino alcohols. The reaction of trans- 28 or cis-oxazolidinone derivative 32 with organocopper reagents proceeds quantitatively with high regio- and diastereoselectivities in anti-S(N)2' fashion. Subsequent oxidative treatment of the newly introduced isopropoxydimethylsilylmethyl group yields trans-L-Ser-L-Pro 31 or trans-L-Ser-D-Pro type isosteres 35, respectively. Of note, synthesized isostere 31 can also be converted to trans-phosphoSer-Pro 42 and trans-Cys-Pro mimetics 44. The present synthetic methodology affords trans-Xaa-Pro alkene-type dipeptide isosteres in high yield with relatively simple manipulation. 相似文献
1000.
Toyofumi Nakanishi Akira Shimizu Nobuhiko Okamoto Arnd Ingendoh Michiko Kanai 《Journal of the American Society for Mass Spectrometry》1995,6(9):854-859
Serum transferrin precipitated with specific antisera was analyzed by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF-MS) and electrospray ionization-mass spectrometry (ESI-MS). When analyzed by MALDI, transferrin showed signal peaks that clearly could be separated from ions of IgG present in the immunoprecipitate. By ESI-MS, when the immunoprecipitates were loaded through a microcapillary polymeric reversed-phase column connected to the electrospray ionization probe, the mass spectra of transferrin were observed with a high signal-to-noise ratio and good resolution. By MALDI/TOF-MS, the observed molecular weight of normal transferrin was ~ 1.2 ku smaller when analyzed in the reflectron mode than in the linear mode. The observed molecular weight of transferrin treated with sialidase was approximately the same in both modes. A comparison between the results obtained in both modes may help to estimate the number of sialic acids on the protein molecule. A transferrin isoform with a molecular weight of ~2.2 ku less than the normal species was identified in the serum of patients with a carbohydrate-deficient glycoprotein syndrome as well as in heavy alcohol consumers. 相似文献