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41.
Contrary to the general assumption that photoreactions in crystals may not proceed with large molecular motions, a pedal-like motion prompted by electronic excitation is believed to be involved during the beta-dimer formation from the crystals of the diamine double salt of trans-2,4-dichlorocinnamic acid and trans-1,2-diaminocyclohexane. 相似文献
42.
Nikolaev S Nilsson P Nishimura S Nomokonov P Nystrand J Obenshain FE Oskarsson A Otterlund I Pachr M Pavliouk S Peitzmann T Petracek V Pinganaud W Plasil F Poblotzki U Purschke ML Rak J Raniwala R Raniwala S Ramamurthy VS Rao NK Retiere F Reygers K Roland G Rosselet L Roufanov I 《Physical review letters》2000,85(17):3595-3599
A measurement of direct photon production in 208Pb+208Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5
1.5 GeV/c. The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation. 相似文献
43.
44.
Raju Suresh Kumar Stephen Michael Rajesh Subbu Perumal Perumal Yogeeswari Dharmarajan Sriram 《Tetrahedron: Asymmetry》2010,21(11-12):1315-1327
Enantiomerically pure (R)-(1-phenylethyl)-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones were synthesized for the first time, and their 1,3-dipolar cycloaddition with nitrile oxides affording di- and trispiroheterocycles regio- and stereoselectively in moderate yields was investigated. These compounds were evaluated against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug-resistant M. tuberculosis (MDR-TB). Among the compounds screened, the dispiroheterocycle, namely, (5R,6R,10S)-3,9-bis(4-chlorophenyl)-10-(2,4-dichlorophenyl)-14-[(E)-(2,4-dichlorophenyl)methylidene]-12-[(R)-1-phenylethyl]-1,4,7-trioxa-2,8,12-tri-azadispiro[4.0.4.4]tetradeca-2,8-diene 5m was found to possess the maximum activity with MIC of 0.49 μM against MTB, being 9.6 and 15.6 times more potent than ciprofloxacin and ethambutol, respectively. Against MDR-TB, 5m displayed maximum activity with an MIC of 0.49 μM, with it thus being more active than rifampicin, isoniazid, ciprofloxacin and ethambutol by 7.8, 23, 77 and 124 times, respectively. 相似文献
45.
46.
Brajesh Pandey M. P. C. Kalita A. Perumal A. Srinivasan H. C. Verma 《Hyperfine Interactions》2008,183(1-3):147-153
Iron nitrides are attractive as they show excellent magnetic properties which can be utilized as recording and permanent magnetic materials for potential applications. Due to the high saturation magnetization and chemical stability, γ ′-Fe4N compound is widely investigated as a promising high density magnetic recording material. γ ′-Fe4N particles were synthesized by conventional gaseous nitriding in a heated atmosphere containing ammonia as a source of nitrogen. X-ray diffraction, 57Fe Mössbauer spectroscopy, vibrating sample magnetometer, scanning electron microscopy and transmission electron microscopy are used for the characterization of the as prepared sample. 相似文献
47.
Alfi Khatib Vikneswari Perumal Qamar Uddin Ahmed Bisha Fathamah Uzir Faridah Abas Suganya Murugesu 《Analytical letters》2017,50(12):1977-1991
Momordica charantia is widely consumed edible fruit. The food and pharmaceutical industries use it as a natural antioxidant. However, the quality control of M. charantia-based medicinal products is questionable due to the complexity of metabolites in this fruit. Hence, this study has developed a statistical model in predicting the antioxidant value through the 2, 2-diphenyl-1 picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power based on infrared spectroscopy with attenuated total reflectance. This technique was reliably used for quality control. Six ethanol extracts (0, 20, 40, 60, 80, and 100% in water) of this plant’s fruit were prepared. The radical scavenging and ferric reducing antioxidant power activities were measured and the chemical profiling of the extracts was fingerprinted by infrared spectroscopy between 4,000 and 600?cm?1 at a resolution of 4?cm?1. Statistical analysis was developed by correlating the bioactivity and infrared spectra of each extract using orthogonal partial least square discriminant analysis. The C–N, C?O, C–O, C–H, and OH infrared signals were positively correlated with biological activity. The antioxidant activity of the fruit of M. charantia may be due to the presence of several antioxidants that work synergistically. 相似文献
48.
K. Swarnalatha E. Rajkumar S. Rajagopal R. Ramaraj I. Sadhiya Banu P. Ramamurthy 《Journal of Physical Organic Chemistry》2011,24(1):14-21
The reaction of phenols with the excited state, *[Ru(bpy)3]2+ (E0 = 0.76 V) and *[Ru(H2dcbpy)3]2+, (dcbpy = 4,4′‐dicarboxy‐2,2′‐bipyridine) (E0 = 1.55 V vs. SCE) complexes in CH3CN has been studied by luminescence quenching technique and the quenching is dynamic. The formation of phenoxyl radical as a transient is confirmed by its characteristic absorption at 400 nm. The kq value is highly sensitive to the change of pH of the medium and ΔG0 of the reaction. Based on the treatment of kq data in terms of energetics of the reaction and pH of the medium, proton coupled electron transfer (PCET) mechanism has been proposed for the reaction. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
49.
Methods to generate triplets of organic molecules within zeolites have been established by employing the Zimmerman rearrangement of barrelenes, oxa-di-π-methane rearrangement of β,γ-unsaturated ketones and photodimerization of acenaphthylene as probe reactions. The two methods, heavy cation effect and triplet sensitization, are well established solution techniques and these work well within zeolites. The Zimmerman rearrangement of dibenzobarrelene is enhanced even within Li+ and Na+ exchanged zeolites and these are believed to be the result of slowing of the rearrangement to dibenzocyclooctatetraene from S1 through cation-π interaction. The methods described here provide an opportunity to explore the control afforded by the zeolite environment on triplet reactions. 相似文献
50.
Syntheses of several new 3,4‐dihydropyrimidinones (DHPMs) on sodium sulfate solid support have been reported. The microwave enhanced rapid synthesis of the title compounds yielded a good percentage of the DHPMs. The catalytic activity of indium triflate enables to prepare a wide range of DHPMs. Syntheses of 2‐hydroxyphenyl, 2‐hydroxy‐4‐methoxyphenyl pendant groups on DHPMs scaffold are advantages of the present method, which are rather prone towards cyclization and the presence of free hydroxyl groups on the phenyl ring is confirmed via D2O exchange study. The mechanism of the reaction is expected to proceed via absorption of substrates on the solid support followed by promotion of the reaction by In(OTf)3 coupled with microwave irradiation. 相似文献