全文获取类型
收费全文 | 730篇 |
免费 | 41篇 |
国内免费 | 4篇 |
专业分类
化学 | 613篇 |
晶体学 | 6篇 |
力学 | 2篇 |
数学 | 44篇 |
物理学 | 110篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 18篇 |
2019年 | 15篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 20篇 |
2015年 | 25篇 |
2014年 | 24篇 |
2013年 | 23篇 |
2012年 | 62篇 |
2011年 | 65篇 |
2010年 | 18篇 |
2009年 | 27篇 |
2008年 | 50篇 |
2007年 | 45篇 |
2006年 | 47篇 |
2005年 | 44篇 |
2004年 | 34篇 |
2003年 | 30篇 |
2002年 | 24篇 |
2001年 | 21篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 9篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1985年 | 7篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1968年 | 3篇 |
1963年 | 2篇 |
1961年 | 3篇 |
1959年 | 2篇 |
排序方式: 共有775条查询结果,搜索用时 15 毫秒
111.
Zhang X Kobayashi N Jiang J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(2):526-531
Nuclear magnetic shielding tensors of porphine have been calculated at density functional B3LYP and PBE level using the gauge independent atomic orbital (GIAO) method. The geometries used were optimized using the 6-31G(d) basis set and the NMR calculations were performed using 6-31G(d) and 6-311G(d,p) basis sets, respectively. The calculated NMR shielding tensors and chemical shifts of porphine are compared with previous calculations as well as experimental data and satisfying results are obtained. Further NMR calculations are extended to metal-free and metallo-porphyrazine, -phthalocyanine, and -naphthalocyanine for the first time and the results are compared with experimental data available. The chemical shifts of the atoms in these compounds are assigned according to the experimental data available. 相似文献
112.
Hiyoshi RI Kohno Y Takahashi O Nakamura J Yamaguchi Y Matsumoto S Azuma N Ueda K 《The journal of physical chemistry. A》2006,110(32):9816-9827
The Raman spectra of alpha form 5-nitro-2,4-dihydro-1,2,4-triazole-3-one (alpha-NTO, space group P) were measured in a high-pressure vessel diamond anvil cell (DAC). The pressure was increased to 27.6 GPa. In general, Raman bands show a blue shift because of the nature of the molecule packing as a high-pressure effect, but some particular bands exhibited a red shift, disappearance, split, or slight shifting in our experiments. Those red-shifting bands concerning hydrogen bonds, i.e., carbonyl and amino groups, are likely to work as a stabilizer against stimuli to the molecule or crystal. This stabilizing nature might characterize the insensitivity of NTO. Molecular dynamic (MD) calculations were performed to reveal the high-pressure effect of the alpha-NTO crystal. The coordinates of individual atoms in the crystal structure were obtained using X-ray diffraction analysis. The pressure dependence of the power spectra of the correlation functions of the C=O bond length in NTO was calculated. A unique high-pressure effect of the alpha-NTO crystal was found on the power spectra. The peak frequency in the power spectrum of the C=O stretching vibration exhibited a red shift with an increase in pressure to 10.0 GPa, while the peak intensity considerably decreased under the same pressure process, because this bond length increased with an increase in pressure to 10.0 GPa. At a pressure of >20.0 GPa, a blue shift appeared. These results of the MD calculations are in good agreement with our experimental data. 相似文献
113.
114.
115.
C. Kimura B. Beckford T. Fujibayashi T. Fujii Y. Fujii K. Futatsukawa T. Gogami O. Hashimoto Y. C. Han K. Hirose R. Honda K. Hosomi A. Iguchi T. Ishikawa H. Kanda Y. Kaneko M. Kaneta Y. Kasai T. Kawasaki S. Kiyokawa T. Koike K. Maeda N. Matsubara K. Miwa Y. Miyagi S. Nagao S. N. Nakamura A. Okuyama H. Shimizu T. Tamae H. Tamura N. Terada K. Tsukada F. Yamamoto T. O. Yamamoto H. Yamazaki 《Few-Body Systems》2013,54(7-10):1319-1322
Double charged pion photoproductions from the deuteron have been studied at Research Center for Electron Photon Science (ELPH), Tohoku University. Tagged photon beams in an energy range of 0.67 ≤ E γ ≤ 1.08 GeV were impinged on the liquid deuteron target. Produced charged particles were observed with the Neutral Kaon Spectrometer2 (NKS2). The γ d → π + π ? d process was clearly separated among the three charged tracks. We obtained the photon energy dependence of the normalized yields of this process. 相似文献
116.
Hiroki Kanda Brian Beckford Takeji Fujibayashi Takao Fujii Yu Fujii Kenta Futatsukawa Toshiyuki Gogami Yun-Cheng Han Osamu Hashimoto Kentaro Hirose Ryotaro Honda Kenji Hosomi Alan Iguchi Takatsugu Ishikawa Yusuke Kaneko Masashi Kaneta Yuma Kasai Daisuke Kawama Taito Kawasaki Chigusa Kimura Shogo Kiyokawa Takeshi Koike Kazushige Maeda Tomofumi Maruta Nayuta Maruyama Masao Matsubara Koji Miwa Yohei Miyagi Sho Nagao Satoshi N. Nakamura Akira Okuyama Kotaku Suzuki Tadaaki Tamae Hirokazu Tamura Nobuhiro Terada Kyo Tsukada Tie-Shang Wang Fumiya Yamamoto Takeshi O. Yamamoto Hirohito Yamazaki 《Few-Body Systems》2013,54(7-10):1175-1178
Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K 0 with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K 0 + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K 1, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K + Λ. 相似文献
117.
Seto H Yamada NL Nagao M Hishida M Takeda T 《The European physical journal. E, Soft matter》2008,26(1-2):217-223
Membrane fluctuations of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) were investigated by neutron spin echo spectroscopy. The intermediate structure factor was analyzed in terms of the model proposed by Zilman and Granek (Phys. Rev. Lett. 77, 4788 (1996)), and the bending modulus of lipid bilayers was derived. The hardening of a lipid bilayer upon approaching the main transition point in the anomalous swelling regime was observed, which naturally connects the bending modulus in the gel phase below the main transition temperature. 相似文献
118.
119.
Prof. Dr. Masaki Shimizu Sho Nagano Takumi Kinoshita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5162-5167
Fluorescence–phosphorescence dual-emissive compounds are valuable tools for ratiometric luminescence sensing. Herein, it is reported that 2,5-bis(phenylsulfonyl)- and 2,5-bis[bis(4-methoxyphenyl)phosphinyl]-1,4-disiloxybenzenes exhibit dual emission with emission peaks that were easily identified without performing time-gated measurement. The disiloxybenzenes in powder simultaneously fluoresced and phosphoresced at 358–374 and 457–470 nm, respectively, under vacuum. The intensity ratios of the phosphorescence/fluorescence maxima of the disiloxybenzenes in powder and in a thin film of poly(methyl methacrylate) were sensitive to temperature and molecular oxygen, respectively. The plots of the relative intensity versus temperature or partial pressure of molecular oxygen were well fitted with calibration curves defined by an exponential approximation with excellent correlation coefficients R2 (0.9708–0.9921), demonstrating the high potential of the disiloxybenzenes as precious metal-free probes applicable to ratiometric luminescence sensing. 相似文献
120.
Sho Ikeda Ryo Shintani 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5790-5794
A new mode of polymerization, rhodium‐catalyzed stitching polymerization, has been developed for the synthesis of π‐conjugated polymers with bridged repeating units from nonconjugated 1,5‐hexadiynes containing both terminal and internal alkyne moieties as monomers. The polymerization proceeded smoothly with a high degree of stitching efficiency under mild conditions, and 1,5,9‐decatriyne and 1,5,9,13‐tetradecatetrayne monomers could also be employed. The present polymerization strategy would be particularly beneficial for the synthesis of polymers consisting of a repeating unit that is difficult to prepare as a stable monomer because it does not require the use of a preformed bridged π‐conjugated monomer. 相似文献