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101.
Mitsuko Masutani Tadashige Nozaki Hiroki Sasaki Tesshi Yamada Takashi Kohno Kimiko Shimizu Masahiro Gotoh Masahiko Shiraishi Jun Yokota Setsuo Hirohashi Hitoshi Nakagama Takashi Sugimura 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2004,80(2):114
Poly(ADP-ribose) polymerase-1 (Parp-1) is involved in DNA repair and cell-death induction after DNA damage. Parp-1−/− mice show higher susceptibility to the carcinogenic effects of nitrosamine and azoxymethane. To elucidate the role of alterations of the PARP-1 gene in human carcinogenesis, we examined the expression level of PARP-1 gene in various human tumor cell lines. The presence of gross rearrangement of PARP-1 gene in these cell lines was also examined by Southern blot hybridization analysis. The expression levels of PARP-1 gene in several cell lines, including T-cell leukemia cell lines (Molt-4 and CCRF-CEM), colon cancer cell line (WiDr), and gastric cancer cell lines (KATOIII, OKAJIMA, and MKN45) was substantially lower than in other cancer cell lines. Among the 85 analyzed cell lines, structural alteration of PARP-1 gene was detected in a gastric cancer cell line, MKN28. A low level of PARP-1 expression in human cancer could potentially influence cancer cell growth, differentiation and cancer development by affecting genomic instability, as well as the response of tumors to chemo- and radiotherapy. 相似文献
102.
Estradiol extracted with an ODS minicolumn from serum (500 μl) is derivatized with 5-dimethylamino-1-naphthalenesulfonyl (dansyl) chloride at room temperature for 80 min, purified on the ODS minicolumn, separated on silica gel columns (150 × 1.9 mm i.d. and 100 × 1.9 mm i.d.) with n-hexane/chloroform/ethanol (70:30:0.1) as eluent at 3 ml min?1 and detected by the chemiluminescence emission produced in a post-column reaction with bis-(2,4,6-trichlorophenyl) oxalate (8 mM in chloroform containing 100 mM triethylamine) and hydrogen peroxide (600 mM in methanol containing 6% (v/v) sodium acetate buffer at pH 4.0). The overall recovery of estradiol from serum is ca. 90% and the detection limit is ca. 50 pg. 相似文献
103.
Acid catalyzed cyclization of ()-HCO-(CH2)-4-CH=C(Me)-CH(SPh)SiMe3 affords -2-substituted cyclohexanol, while () compound affords the isomer. Those cyclized products are transformed to the corresponding α-methyl γ-lactones. 相似文献
104.
[Pt(0)(binap)(2)] (binap = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) is found to exhibit a luminescence from metal-to-ligand charge transfer state (MLCT) with a quantum yield of 0.12 and a lifetime of 1.2 micros in toluene at an ambient temperature. Prompt fluorescence with a quantum yield of 1.6 x 10(-)(4) is observed by means of a picosecond time-correlated single photon counting technique. The spectrum of the steady-state luminescence is almost identical to that of the prompt fluorescence, indicating that the intense luminescence is mainly delayed fluorescence from thermally activated (1)MLCT. The analysis of the temperature-dependent emission indicates that the energy difference between the (1)MLCT and (3)MLCT is 1.15 x 10(3) cm(-)(1). The lifetime of the prompt fluorescence is determined to be 3.2 ps from the decay of stimulated emission overlapped on subpicosecond transient absorption spectra. The lifetime of the (1)MLCT is much longer than expected from the large spin-orbit coupling constant of 5d (Pt) electrons (4000 cm(-)(1)). Theoretical analysis based on density functional theory reveals that structural distortion in the MLCT states causes large energy splitting between HOMO and HOMO - 1, which prevents a very fast ISC induced by strong spin-orbit interactions between these orbitals. The relatively slow ISC is therefore induced by weak spin-orbit interactions (ca. 50 cm(-)(1)) between ligand-centered molecular orbitals. Theoretical calculations indicate that the phosphorescence observed at lower temperatures is due to intensity borrowing from 4(1)B(2) --> GS transition. However, the large energy difference between HOMO and HOMO - 2 reduces the extent of mixing between the lowest (3)MLCT and 4(1)B(2) due to spin-orbit interaction, thereby decreasing the radiative rate of the phosphorescence. 相似文献
105.
Di(2-pyridyl)ketone dimethylplatinum(ii), (dpk)PtII(CH3)2, reacts with CD3OD at 25 °C to undergo complete deuteration of Pt–CH3 fragments in ∼5 h without loss of methane to form (dpk)PtII(CD3)2 in virtually quantitative yield. The deuteration can be reversed by dissolution in CH3OH or CD3OH. Kinetic analysis and isotope effects, together with support from density functional theory calculations indicate a metal–ligand cooperative mechanism wherein DPK enables Pt–CH3 deuteration by allowing non-rate-limiting protonation of PtII by CD3OD. In contrast, other model di(2-pyridyl) ligands enable rate-limiting protonation of PtII, resulting in non-rate-limiting C–H(D) reductive coupling. Owing to its electron-poor nature, following complete deuteration, DPK can be dissociated from the PtII-centre, furnishing [(CD3)2PtII(μ-SMe2)]2 as the perdeutero analogue of [(CH3)2PtII(μ-SMe2)]2, a commonly used PtII-precursor.Di(2-pyridyl)ketone dimethylplatinum(ii), (dpk)PtII(CH3)2, reacts with CD3OD at 25 °C to undergo complete deuteration of Pt–CH3 fragments in ∼5 h without loss of methane to form (dpk)PtII(CD3)2 in virtually quantitative yield. 相似文献
106.
Kiitiro Utimoto Michio Obayashi Yuho Shishiyama Masaharu Inoue Hitosi Nozaki 《Tetrahedron letters》1980,21(35):3389-3392
Triethylaluminium-mediated reaction of cyanotrimethylsilane with 6-methylbicyclo[4.4.0]dec-1-en-3-one affords a mixture of diastereomeric 1,4-adducts. The reaction is kinetically controlled in toluene, whereas thermodynamically in refluxing THF. 4-Methyl-3-penten-2-one and carvone analogously give the respective 1,4-adducts and a conjugated dienone addords the 1,6-adduct in good yield. 相似文献
107.
Yasuhiro Okuda Yoshitomi Morizawa Koichiro Oshima Hitosi Nozaki 《Tetrahedron letters》1984,25(23):2483-2486
Whereas CuI catalyzed silylmagnesation of the tosylate of 5- hexyn-l-ol with the title reagent affords dimethylphenylsilylmethylenecyclopentane exclusively, the mesylate of 3-butyn-l-ol gives a mixture of unexpected silylcyclobutene and cyclopropylidene derivative. 相似文献
108.
Thermal or photochemical decomposition of ethyl diazoacetate in 2-phenyloxirane gave a complex mixture, the analysis of which indicated that the reaction of carbethoxycarbene had proceeded according to the scheme summarized in Fig. 1. The reaction probably involves intermediate formation of an oxygen-ylide (IV), thus accounting for the observed oxygen-transfer and oxetane formation. Copper-catalysed thermal decomposition resulted in a more selective distribution of products, secondary reactions as well as the tar-formation being drastically reduced. The action of other carbenes such as dihalo-, phenyl- and diphenyl-carbene yielded less or no oxygen-transfer products and the formation of oxetane was not observed. In some cases, especially in the reaction of bis(benzene-sulphonyl)carbene, the major product was cyclic dimers of 2-phenyloxirane.
2-Phenyloxetane reacts more selectively with carbethoxycarbene to produce a mixture of cis and trans isomers of 2-carbethoxy-3-phenyltetrahydrofuran in 72–80% yield. 相似文献
109.
Jun-ichi Hibino Seijiro Matsubara Yoshitomi Morizawa Koichiro Oshima Hitosi Nozaki 《Tetrahedron letters》1984,25(20):2151-2154
The reaction of terminal acetylenes with Bu3SnMgMe, Bu3SnA1Et2, or (Bu3Sn)2Zn in the presence of various transition-metal catalysts provides vinylstannanes in good yields. Whereas copper catalysed stannylmagnesation of 4-benzyloxy-1-butyne gives (E)-4-benzyloxy-1-tributylstannyl-1-butene exclusively, palladium catalysed stannylzincation affords 4-benzyloxy-2-tributylstannyl-1-butene preferentially. 相似文献
110.
The novel, bridged bromocycloheptatriene (4) is obtained by the thermolysis of a tricyclo[6.4.1.01,8]tridecane derivative (6), and the observed anti stereochemistry of the Br atom on C(13) is accounted for by assuming the suprafacial [1,5] hydrogen shift in the intermediate 7. The mother hydrocarbon (8) and syn-methyltropylidene (9), as well as tropone (10), are derived from 4, and the structures of these products are examined spectrometrically. The covalent CBr bond of 4 remains intact under various reaction conditions of nucleophilic substitution, and this is ascribed to the conformational rigidity constrained by the short hexamethylene bridge. The attempted transformation of 4 or 10 to the corresponding tropyllium ion 12 or 14 fails to success and this is again attributed to the bridge effect. 相似文献