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891.
Mori M Ikedo M Hu W Helaleh MI Xu Q Itabashi H Tanaka K 《Journal of chromatography. A》2005,1092(2):250-253
The high-speed ion-exclusion chromatographic determination of dissolved carbon dioxide, i.e., carbonic acid, hydrogencarbonate or carbonate, with conductivity detection was obtained using a small column packed with a weakly acidic cation-exchange resin in the H+-form (40 mm long x 4.6 mm i.d., 3 microm-particle and 0.1 meq./ml-capacity). Two different ion-exchange resin columns, which were a strongly acidic cation-exchange resin in the K+-form and a strongly basic anion-exchange resin in the OH- -form, were connected after the separation column. The sequence of columns could convert dissolved carbon dioxide to KOH having high conductivity response. The enhancement effect for dissolved carbon dioxide could retain even on the vast chromatographic runs, by using the enhancement columns with high ion-exchange capacity above 1.0 meq./ml. The retention time was in 60 s at flow-rate of 1.2 ml/min. The calibration graph of dissolved carbon dioxide estimated as H2CO3- was linear in the range of 0.005-10 mM. The detection limit at signal to noise of 3 was 0.15 microM as H2CO3-. This method was applicable to several rainwater and tap water samples. 相似文献
892.
The mixed-metal cubane-type clusters [(Cp*Mo)3(mu3-S)4RuH2(PR3)][PF(6)] [Cp* = eta5-C5Me5; R = Ph (2), Cy (5)] were effective for the N-N bond cleavage of hydrazine and phenylhydrazine via a disproportionation reaction. The ammonia cluster [(C*Mo)3(mu3-S)4Ru(NH3)(PPh3)][PF6] (3) and/or the unprecedented double-cubane-type cluster with bridging nitrogenous ligands [{(Cp*Mo)3(mu3-S)4Ru}2(mu2-NH2)(mu2-NHNH2)][PF6]2 (4) were isolated from the reaction mixtures, and their structures were determined by X-ray diffraction studies. 相似文献
893.
Shuichi Naito 《Catalysis Surveys from Asia》2005,9(4):243-258
The support effects (SiO2, TiO2, Al2O3, MgO, CeO2 and ZrO2) as well as addition effect of group 6b and 7b elements were studied over various supported group 8–10 metal catalysts. Basic
oxide support improved the selectivity to CO2 and acidic support suppressed the catalytic activity and selectivity. Among the investigated catalysts Pt–Mo/TiO2 was the most active catalysts, whereas Ir–Re/SiO2 was the most selective catalysts for H2 and CO2 formation.
The mechanism of the liquid phase methanol reforming reaction over silica supported Pt–Ru catalyst was studied by kinetic
investigations. The rate of H2 formation over Pt–Ru/SiO2 catalysts was more than 20 times faster than that over Pt/SiO2 catalysts with high selectivity for CO2 (72.3%), indicating a marked addition effect of Ru. In the case of HCHO–H2O reaction over Pt–Ru/SiO2, the H2 formation rate was five times larger than that in the CH3OH–H2O reaction but selectivity to CO2 was only 4%. On the contrary, in the HCOOCH3–H2O and HCOOH–H2O reactions, both high activity and selectivity were observed over Pt–Ru/SiO2. These results clearly indicate that the CO2 formation does not proceed via HCHO decomposition and following water gas shift reaction. 相似文献
894.
Manabu Naito 《Czechoslovak Mathematical Journal》1998,48(3):419-432
The neutral differential equation
is considered under the following conditions: n 2, > 0, = ±1, F(t, u) is nonnegative on [t
0, ) × (0, ) and is nondecreasing in u (0, infin;), and lim g(t) = as t . It is shown that equation (1.1) has a solution x(t) such that
0}}{\text{.}} \hfill \\ \end{gathered} $$
" align="middle" border="0">
Here, k is an integer with 0 k n–1. To prove the existence of a solution x(t) satisfying (1.2), the Schauder-Tychonoff fixed point theorem is used. 相似文献
895.
896.
897.
898.
Hisanao Hazama Hirofumi Nagao Ren Suzuki Michisato Toyoda Katsuyoshi Masuda Yasuhide Naito Kunio Awazu 《Rapid communications in mass spectrometry : RCM》2008,22(10):1461-1466
The mass spectra of peptides obtained with different matrices were compared using a matrix-assisted laser desorption/ionization (MALDI) ion source and a multi-turn time-of-flight (TOF) mass spectrometer, MULTUM-IMG, which has been developed at Osaka University. Two types of solid matrices, alpha-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB), and a liquid matrix made from a mixture of 3-aminoquinoline and CHCA were used. When measuring the peak signal intensity of human angiotensin II [M+H]+ from a fixed sample position, the liquid matrix produced a stable signal over 1000 laser shots, while the signal obtained with CHCA and DHB decayed after about 300 and 100 shots, respectively. Significant differences in the mass resolving power were not observed between the spectra obtained with the three matrices. Signal peak areas were measured as a function of the cycle number in a multi-turn ion trajectory, i.e., the total flight time over a millisecond time scale. For both [M+H]+ of human angiotensin II and bovine insulin, the decay of the signal peak area was the most significant with CHCA, while that measured with DHB was the smallest. The results of the mean initial ion velocity measurements suggested that the extent of metastable decomposition of the analyte ions increased in order of DHB, the liquid matrix, and CHCA, which is consistent with the difference in the decay of the signal peak area as the total flight time increased. 相似文献
899.
900.
Extraction of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion was carried out using 14 kinds of alcohols and 1-octanol/octane mixed solvents as a solvent at 25 degrees C. Alcohols are 1-pentanol, 1-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, 2-octanol, 3-octanol, 1-nonanol, 2-nonanol, 3-nonanol, 5-nonanol and 1-decanol. Among them, 1-octanol was found to be extremely high in extractability for 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with hydroxonium cation. The extraction equilibrium for the systems using 1-octanol/octane mixed solvents was analyzed in detail in order to examine the extraction mechanism for these extraction systems. 2-(2-Pyridylazo)-1-naphthol-4-sulfonate anion was found to be extracted with the hydroxonium ion solvated by three 1-octanol molecules as an ion-pair. The extraction and partition constants of the ion-pair of 2-(2-pyridylazo)-1-naphthol-4-sulfonate anion with solvated hydroxonium ion were estimated in the 1-octanol/octane mixed solvent systems. 相似文献