全文获取类型
收费全文 | 224013篇 |
免费 | 2743篇 |
国内免费 | 1340篇 |
专业分类
化学 | 124574篇 |
晶体学 | 3249篇 |
力学 | 8954篇 |
综合类 | 61篇 |
数学 | 24922篇 |
物理学 | 66336篇 |
出版年
2020年 | 1797篇 |
2019年 | 1931篇 |
2018年 | 2502篇 |
2017年 | 2549篇 |
2016年 | 3683篇 |
2015年 | 2467篇 |
2014年 | 3575篇 |
2013年 | 9011篇 |
2012年 | 7815篇 |
2011年 | 9544篇 |
2010年 | 6737篇 |
2009年 | 6520篇 |
2008年 | 8919篇 |
2007年 | 9050篇 |
2006年 | 8535篇 |
2005年 | 7849篇 |
2004年 | 7007篇 |
2003年 | 6177篇 |
2002年 | 6092篇 |
2001年 | 6763篇 |
2000年 | 5142篇 |
1999年 | 3711篇 |
1998年 | 3092篇 |
1997年 | 3054篇 |
1996年 | 3068篇 |
1995年 | 2670篇 |
1994年 | 2761篇 |
1993年 | 2649篇 |
1992年 | 2865篇 |
1991年 | 2932篇 |
1990年 | 2745篇 |
1989年 | 2653篇 |
1988年 | 2593篇 |
1987年 | 2537篇 |
1986年 | 2558篇 |
1985年 | 3352篇 |
1984年 | 3400篇 |
1983年 | 2835篇 |
1982年 | 3077篇 |
1981年 | 2842篇 |
1980年 | 2639篇 |
1979年 | 2813篇 |
1978年 | 3023篇 |
1977年 | 3062篇 |
1976年 | 3096篇 |
1975年 | 2833篇 |
1974年 | 2935篇 |
1973年 | 2991篇 |
1972年 | 2332篇 |
1971年 | 1851篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
N. A. Borisevich S. L. Dziarzhytski V. A. Povedailo D. L. Yakovlev 《Optics and Spectroscopy》2004,96(6):819-823
The spectra of the fluorescence excitation within the rotational contours of the bands of the pure electronic long-wavelength S 0-S 1 transitions of jet-cooled indole and carbazole molecules and their complexes with water are measured. For the carbazole-water complex, a contour with three maxima is registered, which is possibly related to the occurrence of two isomers, differing in a slight displacement of hydrogen between the nitrogen atom of the imine group of carbazole and the oxygen atom of the water molecule. The degrees of polarization of integral fluorescence upon excitation within the rotational contours of the S 0-S 1 electronic transition bands of the above molecules and their complexes with water are determined for the first time. The coincidence of the calculated (7.7%) and measured (7.3%) values of the degree of polarization upon excitation in the rotational Q branch of the b L 1-A electronic transition of indole confirms the accepted intramolecular orientation of the transition dipole moment at an angle of 38.3° with respect to the principal axis of inertia A. Upon excitation of indole, its complex with water, and carbazole into the P and R branches, the measured and calculated degrees of polarization are also close to each other and amount to 2–3%. This confirms the occurrence of contributions to the fluorescence polarization due to the rotations of the indole molecules around the principal axes of inertia A and C. 相似文献
142.
143.
144.
The logarithmic decrement and shear modulus of a bulk amorphous Zr52.5Ti5Cu17.9Ni14.6Al10 alloy were studied with an inverse torsion pendulum in the range from room temperature to the crystallization temperature and in the frequency range 5–40 Hz. The activation energy spectra of reversible and irreversible structural relaxation were estimated. The results obtained are discussed in the context of a two-energy-level model. 相似文献
145.
146.
The general theory on the transformation of elastic waves at a rigid nodal junction of an arbitrary number of thin plates is considered. The notion of transformation marix is introduced, and a way for computing it and numerical examples are given. Properties of the transformation matrix resulted from the reciprocity principle and the energy conservatin law are studied. In particular, a new relation that expresses the energy conservation low for the case where a wave damped in the direction of the joint of plates is a source of a field is obtained. Bibliography: 18 titles. 相似文献
147.
V. L. Tsymbalenko 《JETP Letters》2003,78(8):493-496
The kinetics of formation of an anomalous phase from a solution with a small 3He impurity was studied in the temperature range 0.2–0.7 K up to a supersaturation of ~30 mbar. The phase diagram was determined for normal and anomalous growths. It is found that, in the presence of impurities, the formation of a fast-growing state is retarded. This experimental fact indicates that the dissipative processes in fluids have an appreciable effect on the phase formation kinetics. The retardation is, possibly, caused by the direct interaction of an impurity with the crystal surface. 相似文献
148.
149.
150.
Makarov V. L. Khlobystov V. V. Kashpur E. F. Mikhal'chuk B. R. 《Ukrainian Mathematical Journal》2003,55(6):942-955
We construct an integral Newton-type interpolation polynomial with a continual set of nodes. This interpolant is unique and preserves an operator polynomial of the corresponding degree. 相似文献