全文获取类型
收费全文 | 489篇 |
免费 | 17篇 |
国内免费 | 1篇 |
专业分类
化学 | 296篇 |
晶体学 | 11篇 |
力学 | 21篇 |
数学 | 52篇 |
物理学 | 127篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 16篇 |
2019年 | 22篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 16篇 |
2015年 | 17篇 |
2014年 | 15篇 |
2013年 | 45篇 |
2012年 | 29篇 |
2011年 | 27篇 |
2010年 | 14篇 |
2009年 | 15篇 |
2008年 | 20篇 |
2007年 | 22篇 |
2006年 | 15篇 |
2005年 | 10篇 |
2004年 | 13篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1963年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有507条查询结果,搜索用时 46 毫秒
61.
62.
T. Aziz S. Ahmad H. Ahrar S. B. Beri V. S. Bhatia S. N. Ganguli S. K. Gupta V. K. Gupta A. Gurtu G. L. Kaul Manjit Kaur A. R. Khan S. Kumar P. K. Malhotra L. K. Mangotra I. S. Mittra Y. Prakash N. K. Rao M. Shafi M. Shyam G. Singh S. K. Tuli Aligharh Collaboration Bombay Collaboration Chandigarh Collaboration Jammu Collaboration Varanasi Collaboration 《Zeitschrift fur Physik C Particles and Fields》1985,27(3):325-328
63.
Giuseppe Giordano Krishnamurthy Shyam Alan C. Sartorelli Walter J. McMurray 《Journal of mass spectrometry : JMS》1992,27(5):633-635
Several 1,2,2-tris(sulfonyl)hydrazines, conceived as prodrugs of 1,2-bis(sulfonyl)hydrazines and synthesized as potential antineoplastic and trypanocidal drugs, were analyzed by mass Spectrometry as part of the confirmation of the structure of these compounds. Since these compounds showed activity against several transplanted animal tumors, an understanding of the mass spectral behavior of these agents is important to gain information should clinical trials and metabolic studies be undertaken. In all spectra, protonated molecular ions were observed. Collision activation resulted in considerable fragmentation in the fast atom bombardment spectra. Rearrangement ions formed by elimination of substituted diimides from the middle of the molecule were observed. Other rearrangements involving the alkyl substituent and sulfonyl oxygen also occurred. 相似文献
64.
Technique and instrumentation to detect reliably, multiplicity of neutrons emitted in sharp bursts (≤100 μs) has been developed
where a burst of as low as 15 neutrons and continuous emission of ⋍10−1 neutron/s may be detected. Using this technique, attempts were made to detect neutron emission from various experiments in
which anomalous nuclear effects (or what is commonly referred to as cold fusion) may be expected to occur. No neutrons, above
our detection threshold, were detected in the recent series of experiments. 相似文献
65.
Numerical differentiation can uncover hidden features in chemical data, but the limitations of the technique used should be understood. A method based on fitting data to a quadratic polynomial gives good signal-to-noise ratios, but systematically low derivative intensities. Central difference methods are more accurate but less tolerant of noise. 相似文献
66.
R.M. Mehra P.C. Mathur A.K. Kathuria Radhey Shyam 《Journal of Physics and Chemistry of Solids》1978,39(3):295-298
D.C. conductivity measurements have been made as a function of temperature and external electric field on bulk amorphous selenium. A decrease in the activation energy with increase of electric field has been observed. This has been interpreted in terms of a mixed, thermally activated and trap limited conduction process. 相似文献
67.
68.
O. S. Narayanaswamy Shyam K. Samanta 《Journal of the mechanics and physics of solids》1982,30(6):427-445
Springback of rectangular bars under combined torsion and tension is investigated. A theoretical model for springback is developed and evaluated by comparing calculated and experimental results. It is concluded that springback is analytically predictable. Both analysis and test data show that an axial tension always reduces angular springback in a twisted bar. The order of plastic deformation is found to be important : twist followed by pull produces smaller angular springback upon release of torque and force than does a deformation in the reverse order. 相似文献
69.
ESR spectra of Cu2+ in LiKSO4 have been studied at different temperatures. The measured g-values suggest a rhombic field for Cu2+ ion in the lattice. Optical absorption spectra of the crystal have been studied at room and liquid nitrogen temperatures. From the nature and position of the observed bands, they have been attributed to Cu2+ ions in D2h symmetry. The orbital reduction parameters obtained indicate a substantial degree of covalency in the bonding of the copper ion. 相似文献
70.
Magnetization and magneto-resistance experiments have been carried out on well characterized samples of the GdBaCo2−xFexO5.5 series. Zero field cooled magnetization measurements in the low concentration Fe samples suggest, that the low temperature anti-ferromagnetic phase transforms sequentially to several ferromagnetic phases, before transforming to a paramagnetic state with increase in temperature. The anti-ferromagnetic to the first ferromagnetic phase transition is associated with a large negative magneto-resistance for Fe fractions upto x=0.075. Isothermal magnetization measurements in the ferromagnetic like region of the samples, suggests the presence of mixtures of two ferromagnetic phases. Similar measurements performed at low temperatures where anti-ferromagnetic-like phase is stabilised suggest the presence of a mixture of anti-ferromagnetic and ferromagnetic phases. Magnetization and magneto-resistance are seen to collapse for Fe fractions, x>0.1. Based on these studies a plausible scenario of the evolution of magnetism with Fe substitution in GdBaCo2O5.5, is suggested. 相似文献