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241.
Yasumitsu Tamura Takayuki Yakura Jun-ichi Haruta Yasuyuki Kita 《Tetrahedron letters》1985,26(32):3837-3840
A short and efficient synthesis of dihydroxyacetone groups from keto groups involving the oxidation of ethynylcarbinol intermediates with [bis(trifluoroacetoxy) iodo] benzene (PIFA), is described. 相似文献
242.
243.
Abe K Amako K Arai Y Asano Y Chiba M Chiba Y Daigo M Emura T Endo I Fukawa M Fukui T Fukushima Y Haba J Haidt D Hayashibara I Hemmi Y Higuchi M Hirose T Hojyo Y Homma Y Hoshi Y Ikegami Y Ishihara N Kamitani T Kanematsu N Kanzaki J Kikuchi R Kondo T Koseki T Kubo K Kurashige H Matsui T Minami M Miyake K Mori S Nagashima Y Nakamura T Nakano I Odaka S Ogawa K Ohama T Ohsugi T Ono A Osabe H Saito H Sakae H Sakamoto H Sakamoto S Sakano M Sakuda M Sasao N Sato M Shioden M Shirai J Suekane F 《Physical review letters》1988,61(8):915-918
244.
245.
Tetsuya Tsujihara Sayaka Endo Tsunayoshi Takehara Takeyuki Suzuki Satoru Tamura Tomikazu Kawano 《Tetrahedron letters》2018,59(25):2450-2453
The synthesis of helically chiral [6]helicene-based sulfonic acid and sulfonamide from enantiomerically pure 1-acetylthio-5,6,9,10-tetrahydro[6]helicene is reported. The first helically chiral disulfonimides were developed as a synthetic application of [6]helicene-based sulfonamide. This new class of organocatalysts was tested in an asymmetric Mukaiyama aldol reaction to obtain up to quantitative yields and enantioselectivities up to 24%. 相似文献
246.
The fundamental properties and extraction capability of an ionic liquid (IL), trioctylammonium nitrate ([HTOA][NO3]), for PdII and PtIV, are investigated. At room temperature, [HTOA][NO3] is a solid (melting point: 30.7 °C), but it becomes a liquid (melting point: 16.7 °C) when saturated with water. Water-saturated [HTOA][NO3] exhibits a viscosity of 267.1 mPa·s and an aqueous solubility of 2.821?×?10?4 mol·dm?3 at 25 °C, and can be used as an extraction solvent without dilution. [HTOA][NO3] exhibits an extremely high extraction capability for PdII and PtIV in dilute hydrochloric acid (0.1–2 mol·dm?3 HCl); the distribution ratio reaches 3 × 104 for both the metals. From electrospray ionization mass spectrometry analysis, the species extracted in the IL phase are [PdCl3]? and [PdCl2(NO3)]? for PdII and [PtCl6]2? and [PtCl5]? for PtIV. A majority of the other transition metals are considerably less or marginally extracted into [HTOA][NO3] from a 0.1 mol·dm?3 hydrochloric acid solution. The extraction capacity of [HTOA][NO3] is greater than that of other hydrophobic ILs such as [HTOA]Cl and bis(trifluoromethanesulfonyl)imide-based ILs. The metals extracted into the IL phase are quantitatively back-extracted using an aqueous solution containing thiourea and nitric acid. By controlling the thiourea concentration and shaking time, PdII and PtIV are mutually separated to some extent in the back extraction process. The IL phase used for the back extraction can be reused for the forward extraction of these metals after scrubbing it with an aqueous nitric acid solution. 相似文献
247.
Taniyuki Furuyama Daichi Tamura Hajime Maeda Masahito Segi 《Tetrahedron letters》2018,59(30):2913-2916
In this study, indolo-naphthyridine-6,13-diones (5a–d) with four different peripheral substituents were prepared via bay-annulation reactions of indigo. The resulting compounds (5a–d) exhibited fluorescence in the red to near-IR region, while the parent indigo molecule showed no fluorescence. Although the peripheral substituents were oriented to the exterior of the π-conjugated system, the electronic structure affected the absorption and fluorescence spectra. Moreover, calculated molecular orbitals and absorption spectra successfully reproduced the experimental absorption spectra and cyclic voltammograms. 相似文献
248.
T. Takeda M. Fujiwara M. Kurosawa N. Takahashi M. Tamura T. Kawabata Y. Fujikawa K. N. Suzuki N. Abe T. Kubota T. Takahashi 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):811-824
In this paper, cheap liquorice residue was used to prepare activated carbon (AC), thioacetamide (TAA) was used to modify the AC, and the adsorption experiments were conducted in the simulated acid radioactive wastewater with low uranium concentration to study the adsorption behavior and mechanism for uranium by TAA modified AC (TAA–AC). The removal efficiency by TAA–AC was 92.1–98.2% from the 1 mg L?1 uranium solution at pH 2–6. The adsorption equilibrium data were well fitted by Dubinin–Radushkevich model, and the maximum adsorption capacity was estimated to be 340 mg g?1. TAA–AC showed an enhanced selectivity for uranium in the presence of competitive ions. Furthermore, the adsorption experiments were conducted in the actual acid radioactive wastewater with low uranium concentration from an in situ leach uranium mine. The high adsorption rate (98.3%) and selectivity (Kd?=?3.78×104 mL g?1) for uranium were observed in the actual acid radioactive wastewater, and the adsorption rate was found to maintain 96.2% over six cycles of adsorption–desorption. 相似文献
249.
250.
Yoshikata Koga Katsutoshi Tamura Sachio Murakami 《Journal of solution chemistry》1995,24(11):1125-1133
Speeds of sound were measured at 25°C in the water-rich region of aqueous 2-butoxyethanol (BE) and 2-butanone (BUT). Density, heat capacity, and thermal expansivity data available in literature were used to calculate isothermal compressibilities,
T
. The composition derivative, N (
T/nB), a third derivative of Gibbs free energy, showed a peak anomaly atx
BE=0.0175 for BE-H2O, and a bend atx
BUT=0.033 for BUT-H2O. nB (nBE or nBUT) is the amount of the solute andx
BE andx
BUT are the respective mole fractions. The location of these anomalies were the same as those of other third derivatives found earlier for the same aqueous solutions. These anomalies were shown earlier to mark the transition point across which the mixing scheme changes in a qualitative fashion. 相似文献