全文获取类型
收费全文 | 2373篇 |
免费 | 3篇 |
国内免费 | 14篇 |
专业分类
化学 | 1018篇 |
晶体学 | 50篇 |
力学 | 75篇 |
数学 | 362篇 |
物理学 | 885篇 |
出版年
2018年 | 12篇 |
2017年 | 10篇 |
2016年 | 21篇 |
2015年 | 14篇 |
2014年 | 28篇 |
2013年 | 81篇 |
2012年 | 33篇 |
2011年 | 63篇 |
2010年 | 59篇 |
2009年 | 83篇 |
2008年 | 73篇 |
2007年 | 95篇 |
2006年 | 68篇 |
2005年 | 58篇 |
2004年 | 57篇 |
2003年 | 70篇 |
2002年 | 81篇 |
2001年 | 69篇 |
2000年 | 50篇 |
1999年 | 74篇 |
1998年 | 66篇 |
1997年 | 53篇 |
1996年 | 58篇 |
1995年 | 55篇 |
1994年 | 47篇 |
1993年 | 64篇 |
1992年 | 55篇 |
1991年 | 49篇 |
1990年 | 51篇 |
1989年 | 34篇 |
1988年 | 38篇 |
1987年 | 41篇 |
1986年 | 47篇 |
1985年 | 39篇 |
1984年 | 76篇 |
1983年 | 49篇 |
1982年 | 35篇 |
1981年 | 48篇 |
1980年 | 32篇 |
1979年 | 33篇 |
1978年 | 34篇 |
1977年 | 50篇 |
1976年 | 33篇 |
1975年 | 30篇 |
1974年 | 29篇 |
1973年 | 27篇 |
1972年 | 17篇 |
1971年 | 16篇 |
1970年 | 12篇 |
1963年 | 9篇 |
排序方式: 共有2390条查询结果,搜索用时 0 毫秒
41.
J. -P. Wintenberger 《Inventiones Mathematicae》1995,120(1):215-240
Résumé Soit
:G
E
H(Q
) un système de représentations galoisiennes -adiques associées à un motif sur un corps de nombresE et à valeurs dans un groupe algébriqueH. SoitHH une isogénie centrale telle que la structure de Hodge complexe se relève àH. Nous prouvons, au moins dans certains cas, que, après restriction à une extension finieE deE, le système de représentations galoisiennes se relève àH.
Oblatum 1-VIII-1993 @ 10-X-1994 相似文献
Let :G E H(Q ) be a system of -adic Galois representations associated to a motive over a number fieldE with values in the algebraic groupH. LetHH be a central isogeny such that the complex Hodge structure lifts toH. The main result is that, under some convenient hypothesis, and after restriction to a finite extension, the system of Galois representations lifts toH.
Oblatum 1-VIII-1993 @ 10-X-1994 相似文献
42.
We experimentally demonstrate vector phase conjugation in Cr4+:YAG saturable absorber at 1.06m with nanosecond pulses using degenerate four-wave mixing with linearly-polarized pump beams of arbitrary strengths. The experimental results show that the phase conjugate wave produced by this method can correct depolarisation induced by a birefringent medium. 相似文献
43.
C. Illgner K. -P. Lieb P. Schaaf H. Köster K. Mann G. Marowsky 《Applied Physics A: Materials Science & Processing》1996,62(3):231-236
Laser nitriding of Armco iron in nitrogen was studied for KrF-excimer-laser irradiation. The influence of the energy density and number of pulses on the nitrogen take-up and the nitride phases formed was investigated using Resonant Nuclear Reaction Analysis (RNRA) and Mössbauer spectroscopy. Besides the original a-iron, austenite-Fe(N), martensite-Fe(N),-Fe2+N, and-Fe16N2 were identified. The fraction of the e-phase was found to increase with the number of pulses and the energy density. A threshold energy density of 1.8(2) J/cm2 for the laser nitriding process was found. 相似文献
44.
J. W. G. Bentz H. -P. Ewinger J. Goschnick G. Kannen H. J. Ache 《Fresenius' Journal of Analytical Chemistry》1993,346(1-3):123-127
Summary Previous work on the quantification and localization of organically bound elements with plasma-based SNMS for the characterization of microparticles has been continued. Relative detection factors for 10 elements have been determined. Except for lead and bromine a principle proportionality to atomic ionization probabilities is shown. A moderate matrix dependence of less than 40% variation was found even when inorganic and organic materials are included. For depth calibration, erosion rates of organic materials were determined from the time interval necessary to sputter through planar single-layers and Langmuir-Blodgett multi-layer systems with known thickness, as well as from gravimetric powder measurements. Depth propagation rates were 0.7 nm·sec–1 for polymers and 2.3 nm·sec–1 for aromatic compounds, when 400 eV argon ion bombardment with 0.7 mA·cm–2 was used. A depth resolution of 30 nm has been obtained. Model particles of 5 m size have been coated with fluoranthene. Inspection with SNMS revealed an incomplete coating covering only 20% of the microparticle surface with an average thickness of the partial coating of 300 nm. Subsequent characterization using laser-induced fluorimetry confirmed the amount of fluoranthene coating measured by SNMS. 相似文献
45.
46.
E. Blasius K.-P. Janzen W. Adrian W. Klein H. Klotz H. Luxenburger E. Mernke V.B. Nguyen T. Nguyen-Tien R. Rausch J. Stockemer A. Toussaint 《Talanta》1980,27(2):127-141
Exchangers with cyclic polyethers as anchor groups have a large range of applications such as separations of cations with a common anion, of anions with a common cation, and of neutral organic compounds, and the determination of water by elution chromatography. Some crown ether monomers, especially 4- and 4,4′-alkyl-substituted benzo-derivatives are suitable for extractions and their adducts with heteropoly acids are used as liquid ion-exchangers. The exchangers are also applied in thin-layer chromatography and thin-layer electrophoresis. Furthermore the exchangers are successfully used in preparative chemistry, e.g., in salt conversions in order to isolate salts which are difficult to prepare by other means, in isolation and purification of organic compounds, and for anion activation in organic reactions. 相似文献
47.
Zusammenfassung In der vorliegenden Arbeit wird das Sedimentations-gleichgewicht des Systems Na6[H2W12O40]-NaClO4-H2O bei 25 °C untersucht. Die scheinbare Ladungszahl des Natriummetawolframats wird als Funktion der NaClO4-MolalitätmNaClO4 ermittelt. Aus dieser Abhängigkeit kann für die summarische Dissoziation des NatriummetawolframatsNa2[H2W12O4o] 6Na+ + [H2W12O40]6– die DissoziationskonstanteK in Gegenwart von NaClO4 als Fremdelektrolyt zuK=0,08 mol6·kg–6 bestimmt werden.Der Kreuzdifferentialquotient
(
PXz
, ist der Trace-Aktivitätskoeffizient des Natriummetawolframats) wird ebenfalls als Funktion der NaClO4-Molalität ermittelt.Die Konzentrationsabhängigkeit des Trace-Aktivitätskoeffizienten zeigt einen Verlauf, wie er unseres Wissens nach noch nicht von anderen Autoren beobachtet wurde.
Mit 5 Abbildungen und 1 Tabelle 相似文献
Summary An ultracentrifugal study of the sedimentation equilibrium of the system Na2[H2W12O40]-NaClO4-H2Oat 25 °C is presented. The dependency of the apparent charge of the sodium metatungstate on NaClO4-molality is investigated. From these data the dissociation constant for the dissociation of the sodium metatungstate in the presence of NaClO4 according to the equationNa[H2W12O40] 6Na+ + [H2W12O40]6– is calculated toK=0.08 mol6·kg–6. The cross differential quotient ( PXz is the trace activity coefficient of the sodium metatungstate) shows a behavior in its dependence on NaClO4-molality which to our knowledge has not yet been reported by other authors.
Mit 5 Abbildungen und 1 Tabelle 相似文献
48.
Reactivity of Monophosphine Platinum(0) Complexes with SO2 . The addition reaction of (PPh3)Pt(ViSi) (ViSi = {η2-H2C?CHSiMe2}2O) ( 1 ) with SO2 gives within 30 min the red SO2 complex (PPh3)Pt(η2-H2C?CHSiMe2- OSiMe2CH?CH2)(SO2) ( 2 ). A reaction time of 24 h with SO2 leads to the elimination of the ViSi ligand, and the unstable monomeric intermediate (PPh3)Pt(SO2) cyclo- trimerizes to the stable cluster [Pt(PPh3)(SO2)]3 ( 3 ). 3 is also obtained within 30 min by the reaction of (PPh3)Pt(C2H4)2 ( 4 ) with SO2. The crystal structure of 3 has been determined; space group P21/n, Z = 4, a = 1 606.1(3), b = 1 019.3(1), c = 3 624.6(5) pm, β = 93.67°, R/Rw = 0.102/0.121. 相似文献
49.
50.
Aqueous nitrosation of primary α-carbonyl diazo compounds (ethyl diazoacetate, diazoacetone, diazoacetophenones) yields α-carbonyl nitrile oxides, R? CO? CNO; their formation is demonstrated by 1,3-dipolar addition reactions. 相似文献