全文获取类型
收费全文 | 124篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 58篇 |
力学 | 1篇 |
数学 | 26篇 |
物理学 | 41篇 |
出版年
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2013年 | 6篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1962年 | 1篇 |
1944年 | 2篇 |
1943年 | 1篇 |
1939年 | 1篇 |
1935年 | 1篇 |
1931年 | 2篇 |
1930年 | 1篇 |
排序方式: 共有126条查询结果,搜索用时 718 毫秒
41.
The peak absorption coefficients for two near-infrared absorptions of monomethylhydrazine, CH3-N2H3, (MMH) were measured. Absorption bands located at 1.524 μm (6560 cm-1), 1.557 μm (6423 cm-1), and 1.583 μm (6316 cm-1) are assigned to the υ = 2 overtones of the infrared N-H stretching fundamentals at 3317, 3245 and 3177 cm-1. An absorption band located at 1.04 μm (9620±100 cm-1) is assigned to the υ = 3 overtone of one of these fundamentals. The peak absorption coefficients (10) at 1.524 μm (6560±20 cm-1) and 1.04 μm (9620±100 cm-1) are 31 × 10-3 and 0.97 × 10-3 (cm atm)-1, respectively. Uncertainties in these coefficients were estimated to be less than ±20% due primarily to uncertainties in the partial vapor pressure of MMH. 相似文献
42.
43.
44.
In the isostructural cyanobridged chain compounds N(CH3)4MnIIMIII(CN)6 · 8H2O high spin Mn(II) ions couple antiferromagnetically to low spin Mn(III) of Fe(III) ions. The MnII–MnIII compound orders ferrimagnetically below TN = 28.5 ± 1 K. The tetragonal a and b axes are easy ones for the magnetic moments. In the MnII–FeIII compound antiferromagnetic order occurs below TN = 9.3 K, with spins aligned along the tetragonal c axis. The compound undergoes a meta-magnetic transition from the antiferromagnetic to a ferrimagnetic phase. This occurs at 2 K for a field Hcrit ≈ 1.2 T. The temperature dependence of Hcrit, which vanishes at TN, is followed. The tricritical temperature T1 is ~ 5 K. 相似文献
45.
46.
Embedded-atom method potentials and atomistic models of coherent (010) interfaces were used to study slip across interfaces in cube-on-cube oriented Cu/Ni nanolayered materials. (111) disconnections form during slip across Cu–Ni interfaces and become significant barriers to continued deformation. A significant barrier exists for the flat coherent interface owing to the large coherency stresses in the Cu/Ni layers that must be overcome by applied stresses but, once these have been overcome, interface transection occurs readily. A disconnection adds an additional barrier because of a residual dislocation with a Burgers vector magnitude equal to the difference between b Cu and b Ni. This barrier depends on the position of the disconnection relative to the glide plane of the transecting glide dislocation and on the disconnection height. Disconnections cause work hardening that prevents shear band formation during deformation and encourages homogeneous shear processes. Disconnection energies are shown to be relatively small and to depend on the disconnection type and size. 相似文献
47.
Design and specifications of a 4-channel logging tool for simultaneous measurement of natural gamma-radiation, caliper and scattered gamma-radiation from a 137Cs source spaced 15 and 35 cm from detectors are described. The sonde has a diameter of 60 mm and can be applied in wells with diameters of 76 to 350 mm. It is pressed to the sidewall during measurement. The determination of formation density from data measured with the two spacings is demonstrated by two examples considering perturbation parameters as borehole diameter, mud density, and the medium between tool and borehole wall. Es werden die Konstruktionsprinzipien und die Einsatzparameter einer 4kanaligen Bohrlochmeβsonde zur gleichzeitigen Messung der natürlichen radioaktiven γ-Strahlung, des Kalibers der Bohrung und der rückgestreuten γ-Strahlung einer 137Cs-Strahlungsquelle mit 15 und 35 cm Abstand zwischen Quelle und Deteklor vorgestellt. Mit 60 mm-Auβendurchmesser ist die Sonde in Bohrungen von 76 bis 350 mm Durchmesser einsetzbar; sie wird während der Meβfahrt an die Bohrlochwand angedrückt. Die Auswertemöglichkeiten der beiden Sondenlängen zur Bestimmung der Gebirgsdichte unter dem Einfluβ von Störparametern wie Bohrlochdurchmesser, Spülungsdichte und Zwischenmedium zwischen Bohrlochsonde und Bohrlochwand werden dargestellt und an zwei Meβbeispielen erläutert. 相似文献
48.
Hayashi T Caranto JD Matsumura H Kurtz DM Moënne-Loccoz P 《Journal of the American Chemical Society》2012,134(15):6878-6884
Flavodiiron proteins (FDPs) play important roles in the microbial nitrosative stress response in low-oxygen environments by reductively scavenging nitric oxide (NO). Recently, we showed that FMN-free diferrous FDP from Thermotoga maritima exposed to 1 equiv NO forms a stable diiron-mononitrosyl complex (deflavo-FDP(NO)) that can react further with NO to form N(2)O [Hayashi, T.; Caranto, J. D.; Wampler, D. A; Kurtz, D. M., Jr.; Mo?nne-Loccoz, P. Biochemistry 2010, 49, 7040-7049]. Here we report resonance Raman and low-temperature photolysis FTIR data that better define the structure of this diiron-mononitrosyl complex. We first validate this approach using the stable diiron-mononitrosyl complex of hemerythrin, Hr(NO), for which we observe a ν(NO) at 1658 cm(-1), the lowest ν(NO) ever reported for a nonheme {FeNO}(7) species. Both deflavo-FDP(NO) and the mononitrosyl adduct of the flavinated FPD (FDP(NO)) show ν(NO) at 1681 cm(-1), which is also unusually low. These results indicate that, in Hr(NO) and FDP(NO), the coordinated NO is exceptionally electron rich, more closely approaching the Fe(III)(NO(-)) resonance structure. In the case of Hr(NO), this polarization may be promoted by steric enforcement of an unusually small FeNO angle, while in FDP(NO), the Fe(III)(NO(-)) structure may be due to a semibridging electrostatic interaction with the second Fe(II) ion. In Hr(NO), accessibility and steric constraints prevent further reaction of the diiron-mononitrosyl complex with NO, whereas in FDP(NO) the increased nucleophilicity of the nitrosyl group may promote attack by a second NO to produce N(2)O. This latter scenario is supported by theoretical modeling [Blomberg, L. M.; Blomberg, M. R.; Siegbahn, P. E. J. Biol. Inorg. Chem. 2007, 12, 79-89]. Published vibrational data on bioengineered models of denitrifying heme-nonheme NO reductases [Hayashi, T.; Miner, K. D.; Yeung, N.; Lin, Y.-W.; Lu, Y.; Mo?nne-Loccoz, P. Biochemistry 2011, 50, 5939-5947 ] support a similar mode of activation of a heme {FeNO}(7) species by the nearby nonheme Fe(II). 相似文献
49.
Peter L. Lee Deming Shu Mohan Ramanathan Curt Preissner Jun Wang Mark A. Beno Robert B. Von Dreele Lynn Ribaud Charles Kurtz Sytle M. Antao Xuesong Jiao Brian H. Toby 《Journal of synchrotron radiation》2008,15(5):427-432
A dedicated high‐resolution high‐throughput X‐ray powder diffraction beamline has been constructed at the Advanced Photon Source (APS). In order to achieve the goals of both high resolution and high throughput in a powder instrument, a multi‐analyzer detector system is required. The design and performance of the 12‐analyzer detector system installed on the powder diffractometer at the 11‐BM beamline of APS are presented. 相似文献
50.