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281.
A Novel Synthetic Protocol for the Heteroannulation of Oxocarbazole and Oxoazacarbazole Derivatives through Corresponding Oxoketene Dithioacetals
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Ruchi Tyagi Navjeet Kaur Bhawani Singh Dharma Kishore 《Journal of heterocyclic chemistry》2014,51(1):18-23
An efficient novel strategy for the heteroannulation of 6,7‐dihydropyrazolo[3,4‐b]carbazol‐8(1H,5H,9H)‐one 4 and 5‐N‐benzyl‐6,7‐dihydropyrazolo[3,4‐b]carbazol‐8(1H,9H)‐one 5 has been developed to allow the incorporation of pyrazole, isoxazole, pyrimidine, benzodiazepine, and benzothiazepine rings through their corresponding oxoketene dithioacetal derivatives 6 and 7 , respectively. 相似文献
282.
283.
A series of bis-sulfosuccinate anionic gemini surfactants were synthesized from meristyl alcohol (BSGSMA1,4; BSGSMA1,6, and BSGSMA1,8) containing 4, 6, and 8 methylene chains as different flexible spacer lengths. The chemical structures of synthesized geminis were confirmed by using spectroscopic analytical techniques, viz., elemental analysis, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy(NMR). Investigations were carried out to examine the effect of different spacer length and different salts (organic and inorganic) on surface and fluorescence properties of prepared gemini surfactants. The results of surface properties shown that surface tension at CMC (?CMC) and critical micelle concentration (CMC) were reduced and pC20 value was enhanced with increased spacer length. Fluorescence investigations were also revealed the significance of longer spacer with the concluded remarks of higher aggregation number and reduced micropolarity for BSGSMA1,8 having elongated flexible spacer. The results of salts studies had shown the better results for organic salts as compared to inorganic salts. 相似文献
284.
The mechanism of 1,4 alkyl group migration in hypervalent halonium ylides: the stereochemical course
Moriarty RM Tyagi S Ivanov D Constantinescu M 《Journal of the American Chemical Society》2008,130(24):7564-7565
Rhodium(II)-acetate-catalyzed decomposition of either 1,3-cyclohexanedione phenyliodonium ylide or 5,5-dimethyl-1,3-cyclohexanedione phenyliodonium ylide in the presence of alkyl halides yields the corresponding 3-alkoxy-2-halocyclohex-2-enones via a 1,4 alkyl group migration shown to be concerted and intramolecular. In the case of (S)-alpha-phenethyl chloride, the rearrangement proceeds with essentially 88.6% retention of configuration. Theoretical calculations at the B3LYP/6-31G level reveal an activation energy of 5.4 kcal/mol for the process. A Claisen-like rearrangement occurs in the case where allylic halides, such as dimethylallyl or methallyl chorides, are used. The mechanistic pathway proposed for these processes involves addition of the halogen atom of the alkyl or allyl halide to the rhodium carbenoid from the iodonium ylide to yield a halonium intermediate that undergoes halogen to oxygen group migration. Aryl halides, such as chloro-, bromo-, iodo-, and fluorobenzene, behave differently under the same reaction conditions, yielding the product of electrophilic aromatic substitution, namely, the 2-(4-halophenyl) 1,3-cyclohexanedione. 相似文献
285.
Chandra S Raizada S Tyagi M Sharma PK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(3):816-821
Ni(II) and Cu(II) complexes having the general composition [M(L)(2)X(2)] [where L=2-pyridinecarboxaldehyde thiosemicarbazone, M=Ni(II) and Cu(II), X=Cl(-), NO(3)(-) and 1/2 SO(4)(2-)] have been synthesized. All the metal complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, EPR and electronic spectral studies. The magnetic moment measurements of the complexes indicate that all the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry has been assigned for Ni(II) complexes whereas tetragonal geometry for Cu(II) except [Cu(L)(2)SO(4)] which posseses five coordinated geometry. The ligand and its metal complexes were screened against phytopathogenic fungi and bacteria in vitro. 相似文献
286.
Anil Kumar R. Rajesh Gaurav Singhal R.K. Tyagi 《Applied physics. B, Lasers and optics》2007,89(2-3):385-394
Singlet oxygen generated by optical pumping in liquid oxygen/air medium has recently been reported as a potential gain medium
for high power lasers at 1580 nm, by USA’s defense agency DARPA. However, the details with reference to the underlying physics
of this laser and the potential pumping techniques for achieving lasing are still unclear. The present paper investigates
numerically the population kinetics of both upper and lower lasing levels viz. O2
and O2
states in liquid oxygen and discusses the criticality involved in obtaining lasing with this medium. Isotopic liquid oxygen
and liquid air medium where improved conditions for lasing are anticipated, as compared to that in natural liquid oxygen,
have also been considered in the present study. The studies have been carried out for optical pumping by both continuous and
pulsed mode lasers at 1064 nm and 634 nm wavelengths. The temporal variation of small signal gain in each case has been investigated
along with limitations of the same from point of view of lasing. The available and extractable power from all three medium
for an optimum pumping case has also been discussed. The studies reveal that liquid air has high potential for very high power
lasers as compared to both natural and isotopic liquid oxygen.
PACS 31.15.ag 相似文献
287.
A series of compositions having the general formula Nd2−yYyZr2O7 have been synthesized by heating of mixtures of oxides of the components cation and characterized by X-ray diffraction and Raman spectroscopy. Rietveld analysis on the XRD data of all the compositions has been performed which revealed a decrease in lattice parameter as a function of y in the series Nd2−yYyZr2O7 (y=0.0-0.8). Subsequently, a biphasic region starts which continues for y=1.2 and 1.6. The other end member, i.e. Y2Zr2O7 is found to be defect fluorite. On the other hand, Nd3+ has been used as surrogate material for Am3+, which is a minor actinide found in spent nuclear fuel. In the pyrochlore range, the increasing trend of the x-parameter of 48f oxygen indicates the enhancement of disorder in the system. Raman spectroscopy has been employed to validate the data obtained from XRD. The involvement of 48f oxygen in disorder has also been verified by Raman spectroscopic investigation. 相似文献
288.
Rohini Mani Keka R. Chakraborty Joby E. Joy J. Gopalakrishnan A.K. Tyagi 《Journal of solid state chemistry》2010,183(6):1380-1387
We describe an investigation of the structure and dielectric properties of MM′O4 and MTiM′O6 rutile-type oxides for M=Cr, Fe, Ga and M′=Nb, Ta and Sb. All the oxides adopt a disordered rutile structure (P42/mnm) at ambient temperature. A partial ordered trirutile-type structure is confirmed for FeTaO4 from the low temperature (17 K) neutron diffraction studies. While both the MM′O4 oxides (CrTaO4 and FeTaO4) investigated show a normal dielectric property MTiM′O6 oxides for M=Fe, Cr and M′=Nb/Ta/Sb display a distinct relaxor/relaxor-like response. Significantly the corresponding gallium analogs, GaTiNbO6 and GaTiTaO6, do not show a relaxor response at T<500 K. 相似文献
289.
A novel macrocyclic tetradentate ligand 1,5,8,12-tetraaza-2,4,9,11-tetraphenyl-6,7:13,14-dibenzocyclohexadeca- 1,4,8,11-tetraene
(L) has been synthesized. Cobalt(II), nickel(II), and copper(II) complexes of this ligand have been prepared and characterized
by elemental analysis, molar conductance measurements, magnetic susceptibitity measurements, and mass, IR, electronic, and
ESR spectral studies. The molar conductance measurements correspond to a nonelectrolytic nature for all the complexes, which
can be formulated as [M(L)X2] (where M = Co(II), Ni(II), and Cu(II); X = Cl− and NO3−). On the basis of IR, electronic, and ESR spectral studies, an octahedral geometry has been assigned to the Co(II) and Ni(II)
complexes, whereas a tetragonal geometry was found for the Cu(II) complexes. The investigated compounds and uncomplexed metal
salts and the ligands were tested against bacterial species like Sarcina lutea, Escherchia coli, and Staphylococcus aureus. The metal complexes have higher activity than the free ligand and metal salts.
The text was submitted by the authors in English. 相似文献
290.
Manganese(II), cobalt(II), nickel(II) and copper(II) complexes with 1,5,11,15-tetraaza-21,22-dioxo-tricyclo [19,3,1,I6,10]-5,10,15-20-dicosatetraene (L), as a new macrocyclicligand, have been synthesized with and characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, IR, electronic and EPR spectral studies. The molar conductance measurements of the complexes in DMF correspond to non-electrolytic nature of Mn(II), Co(II) and Cu(II) complexes, while showing a 1:2 electrolyte for thew Ni(II) complexe. Thus, these complexes may be formulated as [M(L)X2] and [Ni(L)]X2 (where M = Mn(II), Co(II) and Cu(II) and X = Cl- and NO3 -). On the basis of IR, electronic and EPR spectral studies, an octahedral geometry has been assigned for Mn(II) and Co(II), a square planar for Ni(II) and tetragonal for Cu(II) complexes. In vitro ligand and its metal complexes were also screened against the growth of some fungal and bacterial species in order to assess their antimicrobial properties. 相似文献