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991.
Henning Hopf Stephen A. Matlin Goverdhan Mehta Alain Krief 《Angewandte Chemie (International ed. in English)》2020,59(6):2150-2154
In chemistry and other sciences, hype has become commonplace, compounded by the hypocrisy of those who tolerate or encourage it while disapproving of the consequences. This reduces the credibility and trust upon which all science depends for support. Hype and hypocrisy are but first steps down a slippery slope towards falsification of results and dissemination of fake science. Systemic drivers in the contemporary structure of the science establishment encourage exaggeration and may lure the individual into further steps along the hype‐hypocrisy‐falsification‐fakery continuum. Collective, concerted intervention is required to effectively discourage entry to this dangerous pathway and to restore and protect the probity and reputation of the science system. Chemists must play and active role in this effort. 相似文献
992.
993.
Peter Gross Prof. Dr. Henning A. Höppe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(63):14366-14376
The crystal structure of biuret was elucidated by means of XRD analysis of single crystals grown through slow evaporation from a solution in ethanol. It crystallises in its own structure type in space group C2/c (a=15.4135(8) Å, b=6.6042(3) Å, c=9.3055(4) Å, Z=8). Biuret decomposition was studied in situ by means of temperature-programmed powder XRD and FTIR spectroscopy, to identify a co-crystalline biuret–cyanuric acid phase as a previously unrecognised reaction intermediate. Extensive thermogravimetric studies of varying crucible geometry, heating rate and initial sample mass reveal that the concentration of reactive gases at the interface to the condensed sample residues is a crucial parameter for the prevailing decomposition pathway. Taking these findings into consideration, a study on the optimisation of carbon nitride synthesis from urea on the gram scale, with standard solid-state laboratory techniques, is presented. Finally, a serendipitously encountered self-coating of the crucible inner walls by graphite during repeated synthetic cycles, which prove to be highly beneficial for the obtained yields, is reported. 相似文献
994.
Freitod in Dahlem (1915): Unveröffentlichte Briefe von Edith Hahn und Lise Meitner über Dr. Clara Haber geb. Immerwahr
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Eckart Henning 《无机化学与普通化学杂志》2016,642(6):432-436
The present contribution contains previously unpublished letters by Clara Haber's contemporaries Edith Hahn and Lise Meitner that were written within two weeks of Clara Haber′s tragic suicide. It also contains a commentary about the circumstances of obtaining these letters as well as notes concerning their interpretation. 相似文献
995.
996.
997.
Frank Seela Xiaohua Peng Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o94-o97
The structures of the isomeric nucleosides 4‐nitro‐1‐(β‐d ‐ribofuranosyl)‐1H‐indazole, C12H13N3O6, (I), and 4‐nitro‐2‐(β‐d ‐ribofuranosyl)‐2H‐indazole, C12H13N3O6, (II), have been determined. For compound (I), the conformation of the glycosylic bond is anti [χ = −93.6 (6)°] and the sugar puckering is C2′‐exo–C3′‐endo. Compound (II) shows two conformations in the crystalline state which differ mainly in the sugar pucker; type 1 adopts the C2′‐endo–C3′‐exo sugar puckering associated with a syn base orientation [χ = 43.7 (6)°] and type 2 shows C2′‐exo–C3′‐endo sugar puckering accompanied by a somewhat different syn base orientation [χ = 13.8 (6)°]. 相似文献
998.
Glasses with the base compositions xNa2O · 15Al2O3 · (85 ? x)SiO2 (x = 8.5, 11 and 16) doped with 0.5 mol% SnO2 were investigated by both square-wave voltammetry and impedance spectroscopy in the temperature range from 1300 to 1600 °C. Each recorded square-wave voltammogram exhibits a well pronounced peak attributed to the Sn2+/Sn4+-redox pair. Impedance spectra were measured in a frequency range from 0.1 to 105 s?1 as a function of the superimposed dc-potential and were simulated using an equivalent circuit taking into account the resistivity of the melt, the electrochemical double layer, a resistor attributed to a kinetically hindered electron transfer and a Warburg parameter which accounts for the diffusion process of Sn4+ and Sn2+ to and from the electrode. Additionally, two impedance elements, a resistor and a capacitance both attributed to adsorption processes were necessary to fit the impedance spectra. 相似文献
999.
Hagen Grossholz Ingo Hartenbach Gunter Kotzyba Rainer Pttgen Henning Trill Bernd D. Mosel Thomas Schleid 《Journal of solid state chemistry》2009,182(11):3071-3075
Using the method to synthesize rare-earth metal(III) fluoride sulfides MFS (M=Y, La, Ce–Lu), in some cases we were able to obtain mixed-valent compounds such as Yb3F4S2 instead. With Eu3F4S2 another isotypic representative has now been synthesized. Eu3F4S2 (tetragonal, I4/mmm, a=400.34(2), c=1928.17(9) pm, Z=2) is obtained from the reaction of metallic europium, elemental sulfur, and europium trifluoride in a molar ratio of 5:6:4 within seven days at 850 °C in silica-jacketed gas-tightly sealed platinum ampoules. The single-phase product consists of black plate-shaped single crystals with a square cross section, which can be obtained from a flux using equimolar amounts of NaCl as fluxing agent. The crystal structure is best described as an intergrowth structure, in which one layer of CaF2-type EuF2 is followed by two layers of PbFCl-type EuFS when sheeted parallel to the (001) plane. Accordingly there are two chemically and crystallographically different europium cations present. One of them (Eu2+) is coordinated by eight fluoride anions in a cubic fashion, the other one (Eu3+) exhibits a monocapped square antiprismatic coordination sphere with four F− and five S2− anions. Although the structural ordering of the different charged europium cations is plausible, a certain amount of charge delocalization with some polaron activity has to take place, which is suggested by the black color of the title compound. Temperature dependent magnetic susceptibility measurements of Eu3F4S2 show Curie–Weiss behavior with an experimental magnetic moment of 8.19(5) μB per formula unit and a paramagnetic Curie temperature of 0.3(2) K. No magnetic ordering is observed down to 4.2 K. In accordance with an ionic formula splitting like (EuII)(EuIII)2F4S2 only one third of the europium centers in Eu3F4S2 carry permanent magnetic moments. 151Eu-Mössbauer spectroscopic experiments at 4.2 K show one signal at an isomer shift of −12.4(1) mm/s and a second one at 0.42(4) mm/s. These signals occur in a ratio of 1:2 and correspond to Eu2+ and Eu3+, respectively. The spectra at 78 and 298 K are similar, thus no change in the Eu2+/Eu3+ fraction can be detected. 相似文献
1000.
Anna Evans Anja Bieberle-Hütter Henning Galinski Jennifer L. M. Rupp Thomas Ryll Barbara Scherrer René T?lke Ludwig J. Gauckler 《Monatshefte für Chemie / Chemical Monthly》2009,16(3):975-983