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41.
Morita Y Nishida S Kobayashi T Fukui K Sato K Shiomi D Takui T Nakasuji K 《Organic letters》2004,6(9):1397-1400
[structure: see text] A bowl-shaped neutral radical with a corannulene system has been designed and synthesized for the first time as a stable solid in air. An unequivocal characterization of the electronic properties of the radical shows that an appreciable amount of spin delocalization extends onto the corannulene unit's curved surface. 相似文献
42.
Gajare AS Toyota K Yoshifuji M Ozawa F 《Chemical communications (Cambridge, England)》2004,(17):1994-1995
1,2-Diphenyl-3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutene was used as an additive ligand in copper-catalysed amination reactions of halobenzenes with amines in the presence of base to afford the corresponding secondary or tertiary amines in good to excellent yields. 相似文献
43.
The electrophilic cyclization of propargylic aziridines is described. 3-Iodopyrroles having a variety of substituents were conveniently synthesized by the reaction of propargylic aziridines with iodine. The resulting substituted 3-iodopyrrole was further functionalized to the tri-substituted pyrroles with high efficiency. 相似文献
44.
Loftus N Miseki K Iida J Gika HG Theodoridis G Wilson ID 《Rapid communications in mass spectrometry : RCM》2008,22(16):2547-2554
High mass accuracy electrospray ionisation multistage tandem mass spectrometry (MS(n)) was applied to metabolite profiling studies on plasma samples derived from two strains of rat (the Zucker (fa/fa) obese strain and the normal wild type). Using a quadrupole ion trap time-of-flight (QIT-TOF) mass spectrometer, metabolite profiling software was applied to locate components of biological significance that could account for the differences between the two strains of rat and a formula prediction software tool was used to help identify individual components. The primary factor discriminating between the two populations was the concentration of endogenous lipids. In the Zucker (fa/fa) obese strain, the dominant ion signals and MS(n) spectra were in agreement with lysoglycerophosphocholine components such as palmitoyllysophosphatidylcholine, 1-oleoylglycerophosphocholine, 1-octadecyl-sn-glycero-3-phosphocholine and 1-stearoylglycerophosphocholine and these were found in relatively higher concentrations compared to the normal wild type. Components were identified using high mass accuracy MS(n) data, formula prediction software and by agreement with published mass spectra through internet databases, rather than using a conventional approach with authentic standards. This application shows that the use of high mass accuracy electrospray ionisation MS(n) together with a software tool can be used effectively to detect and characterise unknown analytes in complex matrices, and represents a promising approach for future profiling studies. 相似文献
45.
T. Kondow A. Matsushita K. Kuchitsu K. Nishiyama Y. Morozumi K. Nagamine 《Hyperfine Interactions》1986,32(1-4):807-812
Surface muons produced in UT-MSL were introduced into argon gas of 4.0±0.2 atm with NO2 (0–30 ppm), and muonium signals were detected in the presence of a transverse (1.7–3.4 G) and a longitudinal magnetic field
(0–3.5 kG) at 295±1 K. The cross section for the transverse relaxation was (11.0±1.0)×10−16 cm2. The relaxation rates in different longitudinal magnetic fields show that the rate does not follow the conventional equation
which assumes that the relaxation occurs mainly by spin-exchange interaction. Similar measurements were performed for the
Mu+O2 system. These findings indicate that chemical reactions contribute to these relaxation rates. 相似文献
46.
47.
48.
Frans C. Mijlhoff Gerrit H. Renes Kunio Kohata Kazuko Oyanagi Kozo Kuchitsu 《Journal of Molecular Structure》1977,39(2):241-252
The structure of 1,1-difluoroethylene was determined, from gas phase electron diffraction data obtained independently in Leiden and Tokyo and the rotational constants of F2CCH2, F2CCHD and F2CCD2 derived from the microwave study by Chauffoureaux. The two electron diffraction data agreed without significant discrepancy. From a joint least squares analysis of the diffraction and microwave data, the following rg bond distances and rz bond angles were derived: CC = 1.340 ± 0.006 Å, C-F = 1.315 ± 0.003 Å, C-H = 1.091 ± 0.010 Å, ∠C-C-F = 124.7 ± 0.3°, ∠C-C-H = 119.0 ± 0.4°, where the uncertainties represent estimated limits of error. 相似文献
49.
Toshifumi Yui Kiego Miyawaki Yoshinobu Kawano Kozo Ogawa 《Journal of carbohydrate chemistry》2013,32(8):905-914
ABSTRACT Miniature crystal models of six small carbohydrates were examined using the PM3 semiempirical quantum mechanics method. The minicrystal structures, consisting of 27 sugar residues, were optimized by the combined procedure of partial optimization and reconstruction of the model, while maintaining the original crystal symmetries. All of the minicrystals were successfully optimized without exhibiting a great increase in an energy at any reconstruction step. Some minicrystals showed a prolonged behavior of optimization cycles. A major source of structure change appeared to arise from hydroxyl group rotations wherein the largest movements mostly occurred in an early optimization stage. No significant deformations in geometry of either residues or hydrogen bonds were observed in the final minicrystal structures. The thermodynamic values calculated for the optimized minicrystals were in reasonably good agreement with the literature data. The present study indicated that the PM3 semiempirical method successfully predicted the basic features of intermolecular hydrogen bonding involved in a condensed system. 相似文献
50.