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71.
Ray L. Frost Silmarilly Bahfenne Jií ejka Jií Sejkora Sara J. Palmer Radek koda 《Journal of Raman spectroscopy : JRS》2010,41(6):690-693
Raman spectroscopy has been used to study the arsenate minerals haidingerite Ca(AsO3OH)·H2O and brassite Mg(AsO3OH)·4H2O. Intense Raman bands in the haidingerite spectrum observed at 745 and 855 cm−1 are assigned to the (AsO3OH)2−ν3 antisymmetric stretching and ν1 symmetric stretching vibrational modes. For brassite, two similarly assigned intense bands are found at 809 and 862 cm−1. The observation of multiple Raman bands in the (AsO3OH)2− stretching and bending regions suggests that the arsenate tetrahedrons in the crystal structures of both minerals studied are strongly distorted. Broad Raman bands observed at 2842 cm−1 for haidingerite and 3035 cm−1 for brassite indicate strong hydrogen bonding of water molecules in the structure of these minerals. OH···O hydrogen‐bond lengths were calculated from the Raman spectra based on empirical relations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
72.
We have used vibrational spectroscopy to study the formula and molecular structure of the mineral penkvilksite Na 2TiSi 4O 11·2H 2O. Penkvilksite is a mineral which may be used in the uptake of radioactive elements. Both Raman and infrared spectroscopies identify a band at ~3638 cm?1 attributed to an OH-stretching vibration of hydroxyl units. The inference is that OH units are involved in the structure of penkvilksite. The formula may be well written as Na 2TiSi 4O 10(OH)2·H 2O. The mineral is characterised by a very intense Raman band at 1085 cm?1 and a broad infrared band at 1080 cm?1 assigned to SiO-stretching vibrations. Raman bands at 620, 667 and 711 cm?1 are attributed to SiO and TiO chain bonds. Water-stretching vibrations are observed as Raman bands at 3197, 3265, 3425 and 3565 cm?1. Vibrational spectroscopy enables aspects of the molecular structure of the mineral penkvilksite to be ascertained. Penkvilksite is a mineral which can incorporate actinides and lanthanides from radioactive waste. 相似文献
73.
Abstract The molybdate‐bearing mineral szenicsite, Cu3(MoO4)(OH)4, has been studied by Raman and infrared spectroscopy. A comparison of the Raman spectra is made with those of the closely related molybdate‐bearing minerals, wulfenite, powellite, lindgrenite, and iriginite, which show common paragenesis. The Raman spectrum of szenicsite displays an intense, sharp band at 898 cm?1, attributed to the ν1 symmetric stretching vibration of the MoO4 units. The position of this particular band may be compared with the values of 871 cm?1 for wulfenite and scheelite and 879 cm?1 for powellite. Two Raman bands are observed at 827 and 801 cm?1 for szenicsite, which are assigned to the ν3(E g ) vibrational mode of the molybdate anion. The two MO4 ν2 modes are observed at 349 (B g ) and 308 cm?1 (A g ). The Raman band at 408 cm?1 for szenicsite is assigned to the ν4(E g ) band. The Raman spectra are assigned according to a factor group analysis and are related to the structure of the minerals. The various minerals mentioned have characteristically different Raman spectra. 相似文献
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76.
Sara J. Palmer Ray L. Frost Godwin Ayoko Tai Nguyen 《Journal of Raman spectroscopy : JRS》2008,39(3):395-401
Raman spectroscopy has been used to characterise synthetic mixed carbonate and molybdate hydrotalcites of formula Mg6Al2(OH)16((CO3)2−,(MoO4)2−)·4H2O. The spectra have been used to assess the molecular assembly of the cations and anions in the hydrotalcite structure. The spectra may be conveniently subdivided into spectral features on the basis of the carbonate anion, the molybdate anion, the hydroxyl units and water units. Bands are assigned to the hydroxyl stretching vibrations of water. Three types of carbonate anions are identified: (1) carbonate hydrogen‐bonded to water in the interlayer, (2) carbonate hydrogen‐bonded to the hydrotalcite hydroxyl surface, (3) free carbonate anions. It is proposed that the water is highly structured in the hydrotalcite, as it is hydrogen bonded to both the carbonate and the hydroxyl surface. The spectra have been used to assess the contamination of carbonate in an open reaction vessel in the synthesis of a molybdate hydrotalcite of formula Mg6Al2(OH)16((CO3)2−, (MoO4)2−)·4H2O. Bands are assigned to carbonate and molybdate anions in the Raman spectra. Importantly, the synthesis of hydrotalcites from solutions containing molybdate provides a mechanism for the removal of this oxy‐anion. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
77.
Raman spectroscopy at both 298 and 77 K has been used to study a series of selected natural smithsonites from different origins. An intense sharp band at 1092 cm−1 is assigned to the CO32− symmetric stretching vibration. Impurities of hydrozincite are identified by a band around 1060 cm−1. An additional band at 1088 cm−1 which is observed in the 298 K spectra but not in the 77 K spectra is attributed to a CO32− hot band. Raman spectra of smithsonite show a single band in the 1405–1409 cm−1 range assigned to the ν3 (CO3)2− antisymmetric stretching mode. The observation of additional bands for the ν3g modes for some smithsonites is significant in that it shows distortion of the ZnO6 octahedron. No ν2 bending modes are observed for smithsonite. A single band at 730 cm−1 is assigned to the ν4 in phase bending mode. Multiple bands be attributed to the structural distortion are observed for the carbonate ν4 in phase bending modes in the Raman spectrum of hydrozincite with bands at 733, 707 and 636 cm−1. An intense band at 304 cm−1 is attributed to the ZnO symmetric stretching vibration. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
78.
Ray L. Frost Jií Sejkora Jií ejka Jakub Plil Silmarilly Bahfenne Elloise C. Keeffe 《Journal of Raman spectroscopy : JRS》2011,42(3):534-539
Raman spectra of two well‐defined types of koritnigite crystals from the Jáchymov ore district, Czech Republic, were recorded and interpreted. No substantial differences were observed between both crystal types. The observed Raman bands were attributed to the (AsO3OH)2− stretching and bending vibrations as well as stretching and bending vibrations of water molecules and hydroxyl ions. The non‐interpreted Raman spectra of koritnigite from the RRUFF database and the published infrared spectra of cobaltkoritnigite were used for comparison. The O H···O hydrogen bond lengths in the crystal structure of koritnigite were inferred from the Raman spectra and compared with those derived from the X‐ray single‐crystal refinement. The presence of (AsO3OH)2− units in the crystal structure of koritnigite was proved from the Raman spectra, which supports the conclusions of the X‐ray structure analysis. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
79.
Ray L. Frost 《Journal of Raman spectroscopy : JRS》2011,42(3):540-543
The Raman spectra of a series of related minerals of the pinakiolité group have been collected and the spectra related to the mineral structure. These minerals are based upon an isolated BO33− ion. The site symmetry is reduced from D3h to C1. Intense Raman bands are observed for the minerals takeuchiité, pinakiolité, fredrikssonité and azoproité at 1084, 1086, 1086 and 1086 cm−1. These bands are assigned to the ν1 BO33− symmetric stretching mode. Low‐intensity Raman bands are observed for the minerals at 1345, 1748; 1435, 1748; 1435, 1750; and 1436, 1749 cm−1, respectively. One probable assignment is to ν3 BO33− antisymmetric stretching mode. Intense Raman bands of the studied minerals at 712 cm−1 are attributed to the ν2 out‐of‐plane bending mode. Importantly, through the comparison of the Raman spectra, the molecular structure of borate minerals with ill‐defined structures can be obtained. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
80.
Ray L. Frost Sara J. Palmer Jií ejka Jií Sejkora Jakub Plil Silmarilly Bahfenne Eloise C. Keeffe 《Journal of Raman spectroscopy : JRS》2011,42(8):1701-1710
Raman spectroscopy has been used to study vanadates in the solid state. The molecular structure of the vanadate minerals vésigniéite [BaCu3(VO4)2(OH)2] and volborthite [Cu3V2O7(OH)2·2H2O] have been studied by Raman spectroscopy and infrared spectroscopy. The spectra are related to the structure of the two minerals. The Raman spectrum of vésigniéite is characterized by two intense bands at 821 and 856 cm−1 assigned to ν1 (VO4)3− symmetric stretching modes. A series of infrared bands at 755, 787 and 899 cm−1 are assigned to the ν3 (VO4)3− antisymmetric stretching vibrational mode. Raman bands at 307 and 332 cm−1 and at 466 and 511 cm−1 are assigned to the ν2 and ν4 (VO4)3− bending modes. The Raman spectrum of volborthite is characterized by the strong band at 888 cm−1, assigned to the ν1 (VO3) symmetric stretching vibrations. Raman bands at 858 and 749 cm−1 are assigned to the ν3 (VO3) antisymmetric stretching vibrations; those at 814 cm−1 to the ν3 (VOV) antisymmetric vibrations; that at 508 cm−1 to the ν1 (VOV) symmetric stretching vibration and those at 442 and 476 cm−1 and 347 and 308 cm−1 to the ν4 (VO3) and ν2 (VO3) bending vibrations, respectively. The spectra of vésigniéite and volborthite are similar, especially in the region of skeletal vibrations, even though their crystal structures differ. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献