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71.
A simple liquid chromatographic method was developed for the determination of sennosides B and A in leaves of Cassia angustifolia. These compounds were extracted from leaves with a mixture of methanol-water (70 + 30, v/v) after defatting with hexane. Analyte separation and quantitation were achieved by gradient reversed-phase liquid chromatography and UV absorbance at 270 nm using a photodiode array detector. The method involves the use of an RP-18 Lichrocart reversed-phase column (5 microm, 125 x 4.0 mm id) and a binary gradient mobile-phase profile. The various other aspects of analysis, namely, peak purity, similarity, recovery, repeatability, and robustness, were validated. Average recoveries of 98.5 and 98.6%, with a coefficient of variation of 0.8 and 0.3%, were obtained by spiking sample solution with 3 different concentration solutions of standards (60, 100, and 200 microg/mL). Detection limits were 10 microg/mL for sennoside B and 35 microg/mL for sennoside A, present in the sample solution. The quantitation limits were 28 and 100 microg/mL. The analytical method was applied to a large number of senna leaf samples. The new method provides a reliable tool for rapid screening of C. angustifolia samples in large numbers, which is needed in breeding/genetic engineering and genetic mapping experiments. 相似文献
72.
The ring-opening addition of methyl 2,3-dimethoxy-6-iodobenzoate to oxabenzonorbornadienes followed by cyclization in the presence of NiBr2(dppe) and Zn metal powder in acetonitrile at 80 degrees C to give the corresponding benzocoumarin derivatives is described. This methodology was then applied to the synthesis of natural product arnottin I, first isolated from Xanthoxylum arnottianum Maxim, using protecting group chemistry. After deprotection and subsequent ring closure, arnottin I was obtained in 21% overall yield after six steps starting from catechol. 相似文献
73.
Madan Lal Mittal 《Journal of Mathematical Analysis and Applications》2006,314(1):75-84
In this note, a sufficient condition for summability of Fourier series has been obtained which in conjunction with the author's Tauberian theorem [M.L. Mittal, A Tauberian theorem on strong Nörlund summability, J. Indian Math. Soc. 44 (1980) 369-377] on strong Nörlund summability gives a sufficient condition for summability [C,1,2] of a Fourier series. This generalizes results due to Prasad [G. Prasad, On strong Nörlund summability of Fourier series, Univ. Roorkee Res. J. 9 (1966-1967) 1-10] and Varshney [O.P. Varshney, Note on H2 summability of Fourier series, Boll. Un. Mat. Ital. 16 (1961) 383-385]. 相似文献
74.
We present results on filtering events having nonstatistical charged neutral fluctuations using Discrete Wavelet Transforms(DWT).
Pb-Pb 105 events at 158 AGeV were generated using VENUS event generator and charged neutral fluctuations were injected event-by-event
using simple DCC modeling. We also filtered events using DWT along with Sliding Window Method. The efficiencies and purities
of samples extracted having nonstatistical charged neutral fluctuations using DWT and sliding DWT are presented. 相似文献
75.
We consider perturbed empirical distribution functions
, where {Ginn, n1} is a sequence of continuous distribution functions converging weakly to the distribution function of unit mass at 0, and {X
i, i1} is a non-stationary sequence of absolutely regular random variables. We derive the almost sure representation and the law of the iterated logarithm for the statistic
whereU
n
is aU-statistic based onX
1,...,X
n
. The results obtained extend or generalize the results of Nadaraya,(7) Winter,(16) Puri and Ralescu,(9,10) Oodaira and Yoshihara,(8) and Yoshihara,(19) among others.Research supported by the Office of Naval Research Contract N00014-91-J-1020. 相似文献
76.
Rajaram Mahalakshmy Rangarajan Venkatesan Pillutla Sambasiva Rao Ramu Kannappan Thekkel Madan Rajendiran 《Transition Metal Chemistry》2004,29(6):623-629
Two new unsymmetrical binucleating ligands, 2-[bis(3-N, N-dimethylaminopropyl)-aminomethyl]-6-[prolin-1-yl)methyl]-4-bromophenol [H 2L1] and 2-[bis(3-N, N -dimethylaminopropyl)aminomethyl]-6-[prolin-1-yl)methyl]-4-methylphenol [H2L2], and their dicopper(II) complexes with different exogenous bridging motifs (OAc, Br and Cl) have been prepared and characterized by spectral, electrochemical, magnetic and e.p.r. studies. Electrochemical studies indicate the presence of two irreversible reduction peaks in the cathodic region. Variable temperature magnetic susceptibility studies of the complexes show that the extent of antiferromagnetic coupling increases in the order: OAc–< Cl–< Br–. Broad isotropic or axial symmetric spectral features are observed in powder e.p.r. spectra of the complexes at 77K. A comparison of the electrochemical and magnetic behaviour of the complexes derived from the ligands is discussed on the basis of an exogenous bridge as well as the substituent at the para position of the phenolic ring. 相似文献
77.
Summary Some copper(II) complexes of the types: Cu(HPPK)-(PPK)X, Cu(HMPK)(MPK)X (where HPPK = syn-phenyl-2-pyridylketoxime, HMPK = syn-methyl-2-pyridylketoxime and X = Cl–, Br–, I–, NO3
–, SCN– or SeCN–) Cu(HPPK)2SO4 3 H2O and Cu(HMPK)2SO4 · 3 H2O were synthesized and characterized by analysis, magnetic susceptibility, e.s.r., reflectance and i.r. spectral measurements. The spectral data suggest that Cu(HPPK)(PPK)X and Cu(HMPK)(MPK)X containcis square-coplanar [Cu(HPPK)(PPK)]+ and [Cu(HMPK)(MPK)]+ units respectively, linked by weakly coordinated anions, giving infinite polymeric highly distorted octahedral chain structures, whereas Cu(HPPK)2SO4 · 3H2O and Cu(HMPK)2SO4 · 3 H2O have acis distorted octahedral structure containing two ligand molecules of ketoxime and a bidentate sulphate group. The polycrystalline e.s.r. spectra suggest a distorted octahedral stereochemistry for the CuII ion involving a
ground-state. By using e.s.r. and reflectance spectral data, the orbital reduction parameters, k11 and k1 were calculated and interpreted in terms of molecular orbital coefficients. 相似文献
78.
Relationship between topochemical indices and inhibition of CDK2/cyclin A by 3-aminopyrazoles was investigated using a data set comprising of 42 3-aminopyrazoles. Three topochemical indices--the Wiener's topochemical index--a distance based topochemical index, atomic molecular connectivity index--an adjacency based topochemical index and superadjacency topochemical index--an adjacency-cum-distance based topochemical index were used for the present investigations. The values of Wiener's topochemical index, atomic molecular connectivity index and superadjacency topochemical index for each of the 42 compounds comprising the data set were computed using an in-house computer program. Resultant data was subsequently analyzed and suitable models were developed after identification of the active ranges. Subsequently, a biological activity was assigned to each of the compounds using these models, which was then compared with the reported CDK2/cyclin A inhibitory activity. High accuracy of prediction ranging from 86 to 89% was observed using these models. 相似文献
79.
80.
Madan Mohan Shri G. Mittal Harish C. Khera Anant K. Sirivastava 《Monatshefte für Chemie / Chemical Monthly》1980,111(1):63-79
Complexes of pyridine-2-aldoxime (Hpox) with iron(II) and chromium(III) of type, [Fe(Hpox)2
X
2] (X=Cl, Br, I or NCS); [Cr(Hpox)3]Cl3·3 H2O; [Cr(Hpox)2
X
2]ClO4 (X=F, Cl or Br) and [Cr(Hpox)2(H2O)2]Br3·H2O were prepared and characterized by analytical X-ray powder diffraction, magnetism, vibrational (conventional and far-infrared) and electronic spectroscopy techniques. X-ray and electronic spectral data indicate that all the complexes except [Cr(Hpox)3]Cl3·3 H2O havetrans-pseudo-octahedral microsymmetry around the metal ion. Infrared spectral data indicate that the ligand, Hpox, behaves like a neutral ligand and coordinates to the metal ion through pyridine nitrogen atom and oxime nitrogen atom in all these complexes. The magnetic susceptibilities of chromium(III) complexes, measured over a temperature range 300–78 K, are independent of temperature whereas the magnetic moments of iron(II) complexes over a temperature range 300–20 K are dependent of temperature. The observed temperature dependence of magnetic moments of iron(II) complexes was used to evaluate the magnitude of orbital reduction factor,k, the low-symmetry distortion parameter, , and the extent of reduction in spin-orbital coupling, . In all these iron(II) complexes the magnetic results indicate the presence of an orbitally non-degenerate,5B2g, ground state. Magnetically unperturbed and perturbedMössbauer spectra of iron(II) complexes at various temperatures have also been reported. Magnetically perturbedMössbauer spectra of iron(II) complexes at 4.2 K in an axial field of 60kGauss indicate that the principal component of electric field gradient tensor is positive and consistent with5B2g ground electronic state in a tetragonal (D
4h) local site symmetry.
Übergangsmetallkomplexe mit Oxim-enthaltenden Liganden, VII. Elektronische und strukturelle Eigenschaften vonFe(II)-undCr(III)-Komplexen mit Pyridin-2-aldoxim
Zusammenfassung Es wurden Komplexe von Pyridin-2-aldoxim (Hpox) mit Fe(II) und Cr(III) vom Typ [Fe(Hpox)2 X 2] (X=Cl, Br, I, NCS), [Cr(Hpox)3]Cl3·3 H2O, [Cr(Hpox)2 X 2]ClO4 (X=F, Cl, Br) und [Cr(Hpox)2(H2O)2]Br3·H2O hergestellt. Charakterisierung und Diskussion von Geometrie und Bindungsverhalten in den Komplexen erfolgte auf Grund von analytischen Daten, Röntgen-Pulveraufnahmen, Elektronenanregungsspektroskopie, Infrarotspektroskopie, magnetischen Messungen undMössbauer-Spektroskopie.相似文献