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41.
Ray A Chattopadhyay S Bhattacharya S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1435-1442
The photo-physical aspects of non-covalently linked assemblies of a series of fullerenes, namely, C60, C70, tert-butyl-(1,2-methanofullerene)-61-carboxylate (1) and [6,6]-phenyl C70 butyric acid methyl ester (2) with a designed zinc phthalocyanine (ZnPc), viz., zinc-1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (3) in toluene medium are studied employing absorption spectrophotometric, steady state and time resolved fluorescence spectroscopic measurements. Of central interest in these investigations is the preferential binding of various fullerenes with ZnPc in toluene. The ground state interaction between fullerenes and 3 is first evidenced from UV-Vis measurements. Steady state fluorescence experiment reveals efficient quenching of the excited singlet state of 3 in presence of both underivatized and derivatized fullerenes. K values for the complexes of C60, C70, 1 and 2 with 3 are determined to be 6500, 22,230, 47,800 and 54,770 dm3 mol(-1), respectively. The magnitude of K suggests that 3 preferentially binds C70 and derivatized C70 in comparison to C60 and 1. Time resolved emission measurements establish that C(70)-3 and 2-3 complexes are stabilized much more in comparison to C(60)-3 and 1-3 systems in terms of charge separation process. Semi empirical calculations employing third parametric method substantiate the strong binding of C70 and its derivative with 3 in terms of heat of formation values of the respective complexes, and at the same time, determine the orientation of bound guest (here fullerenes) with the molecular plane of 3. 相似文献
42.
Dipravath Kumar SethSamaresh Bhattacharya 《Polyhedron》2011,30(15):2438-2443
The reactions of N-(aryl)pyridine-2-aldimines (L-R; R = OCH3, CH3, H, Cl and NO2), derived from pyridine-2-aldehyde and para-substituted anilines, with CuI in methanol under ambient conditions afford a series of brown complexes of the type [{Cu(L-R)I}2]. The structure of the [{Cu(L-OCH3)I}2] complex has been determined by X-ray crystallography. In these dimeric complexes the two copper centers are linked through an iodo-bridge, and the L-R ligands are coordinated to the metal center through the pyridine-nitrogen and imine-nitrogen. All the complexes show characteristic 1H NMR signals and intense MLCT transitions in the visible region. These complexes also show an emission near 465 nm, whilst they are excited at 340 nm, with relatively poor quantum yields (φ ∼0.002 at 298 K). Cyclic voltammetry on all the complexes shows two successive Cu(I)-Cu(II) oxidations on the positive side of SCE, and a reduction of the coordinated imine ligand on the negative side. These copper(I) complexes are found to efficiently catalyze Suzuki type C-C coupling reactions. 相似文献
43.
Tiwari AD Mishra AK Mishra SB Mamba BB Maji B Bhattacharya S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1050-1056
The thiocarbohydrazone Schiff-base ligand with a nitrogen and sulphur donor was synthesized through condensation of pyridine-2-carbaldehyde and thiocarbohydrazide. Schiff-base ligands have the ability to conjugate with metal salts. A series of metal complexes with a general formula [MCl2(H2L)]·nH2O (MNi, Co, Cu and Zn) were synthesized by forming complexes of the N1,N5-bis[pyridine-2-methylene]-thiocarbohydrazone (H2L) Schiff-base ligand. These metal complexes and ligand were characterized by using ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FT-IR), 1H and 13C NMR spectroscopy and mass spectroscopy, physicochemical characterization, CHNS and conductivity. The biological activity of the synthesized ligand was investigated by using Escherichia coli DNA as target. The DNA interaction of the synthesized ligand and complexes on E. coli plasmid DNA was investigated in the aqueous medium by UV-Vis spectroscopy and the binding constant (Kb) was calculated. The DNA binding studies showed that the metal complexes had an improved interaction due to trans-geometrical isomers of the complexes than ligand isomers in cis-positions. 相似文献
44.
We introduce a method of characterization of non-Markovianity using coherence of a system interacting with the environment. We show that under the allowed incoherent operations, monotonicity of a valid coherence measure is affected due to non-Markovian features of the system–environment evolution. We also define a measure to quantify non-Markovianity of the underlying dynamics based on the non-monotonic behavior of the coherence measure. We investigate our proposed non-Markovianity marker in the behavior of dephasing and dissipative dynamics for one and two qubit cases. We also show that our proposed measure captures the back-flow of information from the environment to the system and compatible with well known distinguishability criteria of non-Markovianity. 相似文献
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47.
Prabuddha Bhattacharya Monisha Singha Eshani Das Arundhoti Mandal Manasi Maji Amit Basak 《Tetrahedron letters》2018,59(32):3033-3051
Garratt-Braverman cyclization has emerged as one of the simplest synthetic tool to construct two consecutive CC bonds leading to the formation of various important structural scaffolds having significance in the field of therapeutics and material science. The strategic design of suitable precursor for this cycloaromatization reaction involves the deep understanding of reaction pathways involving diradicals and ions. On the other hand, the reaction offers an unprecedented mechanistic paradox for the chemists to solve. This report aims at outlining the recent mechanistic and synthetic developments with special emphasis on the research outcomes from our laboratory. 相似文献
48.
Summary Mixed ligand complexes of the type [VOLA]ClO4 where L=5-bromosalicylaldehyde (L) or 5-nitrosalicylaldehyde (L) and A=2, 2-dipyridyl (A) or 1, 10-phenanthroline (A) have been prepared. Treatment of the mononuclear complexes, [VOLA]ClO4, withp-phenylenediamine (ppd) orm-phenylenediamine (mpd) yielded homobinuclear [VOLA-NC6H4N-LAVO](ClO4)2, complexes, which were characterised by elemental analyses, spectra, magnetic susceptibility and molar conductance measurements. 相似文献
49.
Priya Budhani Sayed Aftab Iqbal Suman Malik Mamta Bhattacharya Liviu Mitu 《Journal of Saudi Chemical Society》2010,14(3):281-285
The present paper deals with the synthesis and characterization of Schiff base complexes of pyrazinamide an antitubercular drug. Metals selected for complexation are copper, silver, gold, zinc, mercury, iron and cobalt. The complexes have been suitably synthesized and isolated in pure powdered form. Analytical data agrees with the compositions M(L), M′(L)2 and M″(L)2·2H2O, respectively where M = Ag, M′ = Cu, Au, Zn and Hg and M″ = Fe and Co, ligand metal ratios were also confirmed by monovariation method and Job’s method of continuous variation. Molar conductance values suggest the non ionic nature of the complexes. The tentative structure assigned to the complexes on the basis of stoichiometry and analytical data were further supported by spectral studies viz; IR, NMR, magnetic susceptibility and electronic spectra. A preliminary attempt has also been made to compare the potencies of metal complexes with parent drug. The Cu and Ag complexes are giving encouraging results. Particle size studies further suggest that the drug molecule undergoes reduction in size on complexation. 相似文献
50.
We study spectral distortions of diffuse ultra-high energy (UHE) neutrino flavour fluxes resulting due to physics beyond the Standard Model (SM). Even large spectral differences between flavours at the source are massaged into a common shape at earth by SM oscillations, thus, any significant observed spectral differences are an indicator of new physics present in the oscillation probability during propagation. Lorentz symmetry violation (LV) and neutrino decay are examples, and result in significant distortion of the fluxes and of the well-known bounds on them, which may allow UHE detectors to probe LV parameters, lifetimes and the mass hierarchy over a broad range. 相似文献