全文获取类型
收费全文 | 131篇 |
免费 | 0篇 |
专业分类
化学 | 72篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 12篇 |
物理学 | 43篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有131条查询结果,搜索用时 15 毫秒
41.
Bhagat Singh 《Journal of Mathematical Analysis and Applications》1980,78(2):640-647
For the system T′(t) + p(t) T(t) + q(t) T(t ? τ) = ∝0tK(t ? μ) T(μ) dμ for t ? 0, T(t) = g(t) for t ∈ [?τ, 0], conditions have been obtained which ensure that a solution of this system is dominated by a nonoscillatory solution in the interval ¦τ, ∞). 相似文献
42.
We present spin resonance measurements on amorphous Y1?xFex alloys using both bulk (a-YFe2) and thin film (x = 0.70, 0.77, 0.83) samples. At 300 K, in every sample, we have found one strong line (S1) whose frequency and angular dependances imply that it is a uniform mode ferromagnetic resonance in a very thin (≈20–40 nm) surface layer. Previous static measurements indicate that these alloys have no long range order at 300 K. The effective magnetization of the surface layer is a non-monotonic function of the Fe content. Rutherford back scattering experiments on bulk samples are used to demonstrate that there is no significant variation in composition, with depth. We show that S1 cannot be attributed to segregation, surface contamination or crystallinity. We propose that the surface layer is another amorphous phase of the alloy. A second resonance (S3) has been ascribed to some of the superparamagnetic spin clusters known to be present in these systems. As reported earlier, we observe other resonances whose origin is not fully understood. 相似文献
43.
Ajay K. Bose Bhagat Ram W. A. Hoffman A. J. Hutchison M. S. Manhas 《Journal of heterocyclic chemistry》1979,16(7):1313-1316
The strategy used for the stereospecific synthesis of benzofused octams as cepham analogs was the conversion of a 3,4-dihydrothioisocarbostyril to a thioimidate, cycloaddition reaction to form a fused β-lactam and subsequent removal of the alkylthio group by Raney nickel hydrogenolysis. Using azidoacetyl chloride for forming the β-lactam and following known procedures, an amido side chain was generated. Two of the carba analogs of cephalosporin so produced showed low levels of antibacterial activity against a number of gram positive and gram negative organisms. 相似文献
44.
Barry Schneider Bhagat S. Yarlagadda Howard S. Taylor Robert Yaris 《Chemical physics letters》1973,22(2):381-383
The many-body Green's function technique, developed by Schneider, Taylor and Yaris for electron scattering problems, is applied to the calculation of ab-initio effective potentials (pseudo-potentials) in atoms and molecules. Computational results on the ionization potentials, excitation energies and bound-bound oscillator strengths in lithium show quantitative agreement with experiment and contain all the heuristically expected physical effects. 相似文献
45.
Kumar Nitish Gulati Harmandeep Kaur Sharma Aakriti Heer Shilpa Jassal Anupmjot Kaur Arora Lovenish Kaur Simranpreet Singh Atamjit Bhagat Kavita Kaur Arshmeet Singh Harbinder Singh Jatinder Vir Bedi Preet Mohinder Singh 《Molecular diversity》2021,25(1):603-624
Molecular Diversity - Breast cancer is the most prominent, frequently diagnosed and leading cause of death among women. Estrogen is an agonist of estrogen receptor alpha (ER-α), expressed in... 相似文献
46.
Impedance matching in an indigenously developed 2 kW RF-excited fast axial flow (RF-FAF) CO2 laser was seen to be significantly influenced by the capacitance formed between the laser head and the electrodes. We find in the published literature that this capacitance is generally assumed to be negligible while designing the matching network in the RF-FAF CO2 lasers. It is shown that this capacitance could have a significant value and consequently would modify the design of the matching network remarkably for a specific laser design studied in the present case. The widely used discharge load model for capacitively coupled RF (CCRF) discharge excited CO2 laser plasma is extended to include this capacitance. The method of measurement of this capacitance using a bridge and the ANSYS software based simulation of its formation due to the laser head structure are discussed. 相似文献
47.
48.
Parasuraman Karthikeyan Sythana Suresh Kumar Aswar Sachin Arunrao Muskawar Prashant Narayan Pundlik Rambhau Bhagat 《Research on Chemical Intermediates》2013,39(3):1335-1342
An environmentally benign, cheap and reusable L-amino acid functionalized ionic liquid [L-AAIL]/AlCl3 was found to be an effective catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-thione derivatives in good to excellent yield under solvent-free condition. Compared with the classical Biginelli reactions, this method consistently enjoys the advantages of mild reaction conditions, easy work-up, and short reaction time. These one-pot three-component Biginelli products could be separated easily from the catalyst–water system, and the catalyst could be reused at least five times without noticeably reducing catalytic activity. 相似文献
49.
Wright AC Lemdiasov R Connick TJ Bhagat YA Magland JF Song HK Toddes SP Ludwig R Wehrli FW 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,210(1):113-122
A Helmholtz-pair local transmit RF coil with an integrated four-element receive array RF coil and foot immobilization platform was designed and constructed for imaging the distal tibia in a whole-body 7T MRI scanner. Simulations and measurements of the B(1) field distribution of the transmit coil are described, along with SAR considerations for operation at 7T. Results of imaging the trabecular bone of three volunteers at 1.5T, 3T and 7T are presented, using identical 1.5T and 3T versions of the 7T four-element receive array. The spatially registered images reveal improved visibility for individual trabeculae and show average gains in SNR of 2.8× and 4.9× for imaging at 7T compared to 3T and 1.5T, respectively. The results thus display an approximately linear dependence of SNR with field strength and enable the practical utility of 7T scanners for micro-MRI of trabecular bone. 相似文献
50.
We report EPR measurements on amorphous FexNi80-xP14B6 alloys for concentrations less than that required for ferromagnetism. Measurements were made at microwave frequencies between 10 and 35 GHz and at temperatures between 2 and 150 K. We find i) at high temperatures the alloys are simple paramagnets with ? ≈ 2.14 and a relaxation rate (linewidth) increasing linearly with temperature, ii) the linewidth increases at low T and follows an empirical form proposed earlier, iii) as the temperature is decreased, the susceptibility (measured by reference to the line intensities) increases, iv) in order to account for the frequency dependence of the resonance field we must introduce an anisotropy energy with uniaxial symmetry; the “hard axis” being normal to the sample plane. The associated anisotropy constant K' appears at several times the spin glass transition temperature TSG, v) at still lower temperatures ( < 2TSG) another type of anisotropy field appears. The corresponding anisotropy energy is similar to that introduced to explain data on the reentrant alloys of this system and the archetypal spin glasses CuMn and AgMn and the anisotropy constant K has the same type of temperature dependence. However, the frequency dependence of K is different. 相似文献