全文获取类型
收费全文 | 315583篇 |
免费 | 2008篇 |
国内免费 | 655篇 |
专业分类
化学 | 159701篇 |
晶体学 | 4743篇 |
力学 | 15841篇 |
综合类 | 10篇 |
数学 | 36179篇 |
物理学 | 101772篇 |
出版年
2020年 | 2806篇 |
2019年 | 3281篇 |
2018年 | 5367篇 |
2017年 | 5590篇 |
2016年 | 6594篇 |
2015年 | 3439篇 |
2014年 | 5683篇 |
2013年 | 12486篇 |
2012年 | 10465篇 |
2011年 | 12061篇 |
2010年 | 9193篇 |
2009年 | 9467篇 |
2008年 | 11244篇 |
2007年 | 11014篇 |
2006年 | 10294篇 |
2005年 | 11850篇 |
2004年 | 11272篇 |
2003年 | 9300篇 |
2002年 | 7997篇 |
2001年 | 9762篇 |
2000年 | 7189篇 |
1999年 | 5509篇 |
1998年 | 4460篇 |
1997年 | 4361篇 |
1996年 | 4057篇 |
1995年 | 3709篇 |
1994年 | 3657篇 |
1993年 | 3517篇 |
1992年 | 4008篇 |
1991年 | 4388篇 |
1990年 | 4149篇 |
1989年 | 4162篇 |
1988年 | 4052篇 |
1987年 | 4072篇 |
1986年 | 3750篇 |
1985年 | 4690篇 |
1984年 | 4728篇 |
1983年 | 3942篇 |
1982年 | 3994篇 |
1981年 | 3760篇 |
1980年 | 3566篇 |
1979年 | 4134篇 |
1978年 | 4318篇 |
1977年 | 4374篇 |
1976年 | 4423篇 |
1975年 | 4114篇 |
1974年 | 4029篇 |
1973年 | 4226篇 |
1972年 | 3152篇 |
1971年 | 2778篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Sanzharov N. A. Yarovoi A. T. Bekhtereva E. S. Ulenikov O. N. 《Russian Physics Journal》2002,45(10):1024-1031
Analytical formulas are derived that describe the dependences of the transition probabilities in vibrational-rotational spectra of XY3-type molecules with C
3v
symmetry on the rotational quantum numbers. 相似文献
72.
73.
74.
75.
76.
Results of an experiment on investigating the fluctuations of a sound signal with a frequency of 295 Hz on a stationary 32-km-long acoustic path in a shallow sea are presented. Hydrological conditions on the path were characterized by the presence of a weak thermocline and a frequent occurrence of intense internal wave trains. The space-time characteristics of these internal waves were measured in detail. Experimental evidence of the repetition of the forms of internal solitons in the variations of the amplitude and phase of an acoustic signal was obtained. 相似文献
77.
78.
A systematic study on the electrochemical behavior of diosmin in Britton-Robinson buffer (pH 2.0-10.0) at a glassy carbon electrode (GCE) was made. The oxidation process of the drug was found to be quasi-reversible with an adsorption-controlled step. The adsorption stripping response was evaluated with respect to various experimental conditions, such as the pH of the supporting electrolyte, the accumulation potential and the accumulation time. The observed anodic peak current at +0.73 V vs. Ag/AgCl reference electrode increased linearly over two orders of magnitude from 5.0x10(-8) M to 9.0x10(-6) M. A limit of detection down to 3.5x10(-8) M of diosmin at the GCE was achieved with a mean recovery of 97+/-2.1%. Based on the electrochemical data, an open-circuit accumulation step in a stirred sample solution of BR at pH 3.0 was developed. The proposed method was successfully applied to the determination of the drug in pharmaceutical formulations. The results compared favorably with the data obtained via spectrophotometric and HPLC methods. 相似文献
79.
S. Meenakshi B.K. Godwal I. Orgzall S. Tkachev 《Journal of Physics and Chemistry of Solids》2006,67(8):1660-1667
We report the results of an X-ray diffraction study of CdAl2Se4 and of Raman studies of HgAl2Se4 and ZnAl2Se4 at room temperature, and of CdAl2S4 and CdAl2Se4 at 80 K at high pressure. The ambient pressure phase of CdAl2Se4 is stable up to a pressure of 9.1 GPa above which a phase transition to a disordered rock salt phase is observed. A fit of the volume pressure data to a Birch-Murnaghan type equation of state yields a bulk modulus of 52.1 GPa. The relative volume change at the phase transition at ∼9 GPa is about 10%. The analysis of the Raman data of HgAl2Se4 and ZnAl2Se4 reveals a general trend observed for different defect chalcopyrite materials. The line widths of the Raman peaks change at intermediate pressures between 4 and 6 GPa as an indication of the pressure induced two stage order-disorder transition observed in these materials. In addition, we include results of a low temperature Raman study of CdAl2S4 and CdAl2Se4, which shows a very weak temperature dependence of the Raman-active phonon modes. 相似文献
80.
Analytical expressions are obtained that describe the changes in the degree of coherence and in the thickness of the coherence layers occurring upon propagation of a dispersed broadband laser beam. It is found that the greater the tilting of the coherence layers with respect to the phase fronts, the more rapidly the spatial coherence is violated with increasing distance. A comparison with the case of an undispersed beam is performed. It is shown that, as the beam propagates, the decrease in the degree of coherence is accompanied by the appearance of spatial fluctuations of this parameter. The degree of mutual coherence of intersecting dispersed beams with parallel correlated coherence layers, which determines the efficiency of their coherent interaction, is investigated. The existence of spatial fluctuations of the degree of mutual coherence is established. 相似文献