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131.
Kanai A Takeda Y Kuramochi K Nakazaki A Kobayashi S 《Chemical & pharmaceutical bulletin》2007,55(3):495-499
The synthesis of the key intermediate (4) in the proposed route to D8646-2-6 is described. The aldol reaction of the carbohydrate-containing pyrone 7 with the aldehyde 6 was accomplished by using LiHMDS and Sc(OTf)3 or Sn(OTf)2. The stepwise dehydration reaction of the aldol adduct 14, followed by Stille coupling with vinyl stannane 5 which contained phosphonate gave the desired 4. 相似文献
132.
133.
Spatial light modulator with an over-two-octave bandwidth from ultraviolet to near infrared 总被引:1,自引:0,他引:1
We developed a 1-pixel ultraviolet-to-near-infrared (UV-to-NIR) liquid-crystal spatial light modulator (LC-SLM) and clarified its phase modulation properties in detail, for the first time to our knowledge. The employed liquid crystal is transparent over 260-1100 nm. A phase modulation capability of 55.8 rad at 305 nm and 14.0 rad at 1000 nm is enough to compensate for UV-to-NIR nonlinear chirped pulses. The LC-SLM driving parameters of a period T=13 ms and an applied voltage V(DD)=7.0 V were determined. The 648-pixel extension of this new device will permit us to realize the high-power generation of single subcycle optical pulses and the direct UV-to-NIR pulse shaping. 相似文献
134.
The mechanical properties, such as Young's modulus, yield strength, and the elongation at breakage, were investigated for several sulfur-containing biopolymers P(3HB-co-3MP). A series of P(3HB-co-3MP) samples with 3MP unit content ranging from 6.6 to 39.1 mol-% was biosynthesized by fermentation using the PHA-synthesizing bacteria Cupriavidus necator. For comparison, the bacterially synthesized P(3HB) and P(3HB-co-3HP) with the 3HP unit content ranging from 13.1 to 21.1 mol-% were also investigated. It was found that the sulfur-containing P(3HB-co-3MP) is much more durable to stretching. Notably, P(3HB-co-3MP) with the 3MP unit content of only 6.6 mol-% was found to show excellent mechanical properties. 相似文献
135.
Shinichi Yamabe Shoko Yamazaki Shigeyoshi Sakaki 《International journal of quantum chemistry》2015,115(21):1533-1542
Hydride‐transfer reactions between benzylic substrates and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) were investigated by DFT (density functional theory) calculations. The lowest unoccupied molecular orbital of DDQ has the largest extension on two carbonyl oxygens, which comes from two‐step mixing of antisymmetric orbitals of fragment π MOs. Transition‐state (TS) geometries and activation energies of reactions of four benzylic substrates R2? CH2‐para‐C6H4? R1 (R1, R2 = H and/or OCH3) with DDQ were calculated. M06‐2X/6‐311(+*)G* was found to be a practical computational method, giving energies and geometries similar to those of M06‐2X/6‐311++G(3df,2pd) and wB97xD/6‐311++G(3df,2pd). For toluene (R1 = R2 = H), an initiation‐propagation model was suggested, and the calculated kinetic isotope effect k(H)/k(D) = 5.0 with the tunnel correction at the propagating step is in good agreement with the experimental value 5.2. A reaction of para‐MeO? C6H4? CH2(OMe) + DDQ + (H2O)14 → para‐MeO? C6H4? C(?O)H + HOMe + DDQH2 + (H2O)13 was investigated by M06‐2X/6‐311(+*)G*. Four elementary processes were found and the hydride transfer (TS1) is the rate‐determining step. The hydride transfer was promoted by association with the water cluster. The size of the water cluster, (H2O)n, at TS1 was examined. Three models of n = 14, 20, and 26 were found to give similar activation energies. Metal‐free neutral hydride transfers from activated benzylic substrates to DDQ were proposed to be ready processes both kinetically and thermodynamically. © 2015 Wiley Periodicals, Inc. 相似文献
136.
Atmospheric pressure chemical ionization of explosives using alternating current corona discharge ion source
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Dilshadbek Tursunbaevich Usmanov Lee Chuin Chen Zhan Yu Shinichi Yamabe Shigeyoshi Sakaki Kenzo Hiraoka 《Journal of mass spectrometry : JMS》2015,50(4):ii-ii
The high‐sensitive detection of explosives is of great importance for social security and safety. In this work, the ion source for atmospheric pressure chemical ionization/mass spectrometry using alternating current corona discharge was newly designed for the analysis of explosives. An electromolded fine capillary with 115 µm inner diameter and 12 mm long was used for the inlet of the mass spectrometer. The flow rate of air through this capillary was 41 ml/min. Stable corona discharge could be maintained with the position of the discharge needle tip as close as 1 mm to the inlet capillary without causing the arc discharge. Explosives dissolved in 0.5 µl methanol were injected to the ion source. The limits of detection for five explosives with 50 pg or lower were achieved. In the ion/molecule reactions of trinitrotoluene (TNT), the discharge products of NOx? (x = 2,3), O3 and HNO3 originating from plasma‐excited air were suggested to contribute to the formation of [TNT ? H]? (m/z 226), [TNT ? NO]? (m/z 197) and [TNT ? NO + HNO3]? (m/z 260), respectively. Formation processes of these ions were traced by density functional theory calculations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
137.
Akihiro Sasoh Tatsuya Harasaki Takuya Kitamura Daisuke Takagi Shigeyoshi Ito Atsushi Matsuda Kouji Nagata Yasuhiko Sakai 《Shock Waves》2014,24(5):489-500
When a shock wave ejected from the exit of a 5.4-mm inner diameter, stainless steel tube propagated through grid turbulence across a distance of 215 mm, which is 5–15 times larger than its integral length scale \(L_{u}\) , and was normally incident onto a flat surface; the peak value of post-shock overpressure, \(\Delta P_{\mathrm{peak}}\) , at a shock Mach number of 1.0009 on the flat surface experienced a standard deviation of up to about 9 % of its ensemble average. This value was more than 40 times larger than the dynamic pressure fluctuation corresponding to the maximum value of the root-mean-square velocity fluctuation, \(u^{\prime }= 1.2~\hbox {m}/\hbox {s}\) . By varying \(u^{\prime }\) and \(L_{u}\) , the statistical behavior of \(\Delta P_{\mathrm{peak}}\) was obtained after at least 500 runs were performed for each condition. The standard deviation of \(\Delta P_{\mathrm{peak}}\) due to the turbulence was almost proportional to \(u^{{\prime }}\) . Although the overpressure modulations at two points 200 mm apart were independent of each other, we observed a weak positive correlation between the peak overpressure difference and the relative arrival time difference. 相似文献
138.
Abstract By making use of the time delayed double excitation spectroscopy, transient absorption spectra just after the excitation of self-trapped excitons (STE) from the lowest triplet state to higher excited states have been observed to find the transient F-H center pair [F-H]. Absorption bands due to transient [F-H] appeared as a doublet peaking at 2.70eV and 2.86eV (NaCl), at 2.25eV and 2.38eV (KCl) and at 1.97eV and 2.09eV (RbCl) at 108ps after the excitation. The ratio of peak heights between bands at low and high energy sides was 2:1 in all crystals. The results were tentatively understood by a recent theory for the STE by Song et al. (1987). 相似文献
139.
The intermetallic compound Pr(5)Ni(19), which is not shown in the Pr-Ni binary phase diagram, was synthesized, and the crystal structure was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Two superlattice reflections with the Sm(5)Co(19)-type structure (002 and 004) and the Pr(5)Co(19)-type structure (003 and 006) were observed in the 2θ region between 2° and 15° in the XRD pattern using Cu Kα radiation. Rietveld refinement provided the goodness-of-fit parameter S = 6.7 for the Pr(5)Co(19)-type (3R) structure model and S = 1.7 for the Sm(5)Co(19)-type (2H) structure model, indicating that the synthesized compound has a Sm(5)Co(19) structure. The refined lattice parameters were a = 0.50010(9) nm and c = 3.2420(4) nm. The high-resolution TEM image also clearly revealed that the crystal structure of Pr(5)Ni(19) is of the Sm(5)Co(19) type, which agrees with the results from Rietveld refinement of the XRD data. The P-C isotherm of Pr(5)Ni(19) in the first absorption was clearly different from that in the first desorption. A single plateau in absorption and three plateaus in desorption were observed. The maximum hydrogen storage capacity of the first cycle reached 1.1 H/M, and that of the second cycle was 0.8 H/M. The 0.3 H/M of hydrogen remained in the metal lattice after the first desorption process. 相似文献
140.