全文获取类型
收费全文 | 108566篇 |
免费 | 6983篇 |
国内免费 | 6510篇 |
专业分类
化学 | 63431篇 |
晶体学 | 1445篇 |
力学 | 6190篇 |
综合类 | 469篇 |
数学 | 13123篇 |
物理学 | 37401篇 |
出版年
2023年 | 961篇 |
2022年 | 2104篇 |
2021年 | 2517篇 |
2020年 | 2743篇 |
2019年 | 2937篇 |
2018年 | 3254篇 |
2017年 | 3212篇 |
2016年 | 4008篇 |
2015年 | 2938篇 |
2014年 | 4038篇 |
2013年 | 5704篇 |
2012年 | 5790篇 |
2011年 | 6156篇 |
2010年 | 4863篇 |
2009年 | 4818篇 |
2008年 | 5106篇 |
2007年 | 4713篇 |
2006年 | 4297篇 |
2005年 | 3810篇 |
2004年 | 3401篇 |
2003年 | 3022篇 |
2002年 | 3188篇 |
2001年 | 2833篇 |
2000年 | 2254篇 |
1999年 | 1822篇 |
1998年 | 1703篇 |
1997年 | 1449篇 |
1996年 | 1435篇 |
1995年 | 1182篇 |
1994年 | 1281篇 |
1993年 | 1191篇 |
1992年 | 1132篇 |
1991年 | 1214篇 |
1990年 | 1205篇 |
1989年 | 1079篇 |
1988年 | 956篇 |
1987年 | 941篇 |
1986年 | 915篇 |
1985年 | 958篇 |
1984年 | 930篇 |
1983年 | 840篇 |
1982年 | 807篇 |
1979年 | 804篇 |
1978年 | 812篇 |
1977年 | 806篇 |
1976年 | 919篇 |
1975年 | 812篇 |
1974年 | 844篇 |
1973年 | 847篇 |
1972年 | 752篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Some possible errors in determining the gravity anomalies are discussed. Such errors may be caused by an inaccurate calibration of the gravimeter used in an airborne survey system. An approach based on wavelet decompositions is proposed for its additional calibration with the use of flight data obtained during repeated flights. 相似文献
92.
The aim of this study is to construct a quantitative characteristic for the degree of gaze stabilization on a visual target with consideration of physiological constraints. A quality criterion for visual tracking during optokinetic vestibulocervical nystagmus is proposed. The index of imaginary tracking during rotation in the dark allows one to speak of a difference in the image stabilization quality between a healthy person and a patient. Experimental nystagmus data are used to calculate the quality index of visual tracking and the index of imaginary tracking. 相似文献
93.
Chengzhi Qi Mingyang Wang Qihu Qian Jianjie Chen 《Moscow University Mechanics Bulletin》2008,63(5):113-121
The formation mechanisms for the structural hierarchy in geological media are discussed. It is shown that the formation of such a hierarchy is caused by certain external and internal circumstances. The first ones consist in the fact that, because of external actions, the Earth’s poles continuously execute the translational and rotational motions responsible for a regular structure of rock fracture and for the appearance of the scale factor √2. The second ones consist in the fact that, under the action of many random factors and because of external actions, during the formation of geological media there appear dissipative structures and, hence, some self-similar fractal structures are formed. 相似文献
94.
A. V. Ivanov M. Yu. Tsentalovich E. G. Kogan L. G. Tomilova N. S. Zefirov 《Russian Chemical Bulletin》2008,57(8):1676-1679
The chlorination of benzene, toluene, and o-xylene with molecular chlorine in the presence of the phthalocyanine complexes of different structures was studied. The transformations
of the catalysts during the reaction were investigated.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1644–1647, August, 2008. 相似文献
95.
96.
M. K. Bratenko Yu. V. Kadel’nik V. A. Chornous M. V. Vovk 《Russian Journal of Organic Chemistry》2008,44(2):247-250
Oximes of 4-(4-pyrazolyl)-3-buten-2-onees obtained by successive reaction of 3-aryl-4-formylpyrazoles with acetone and hydroxylamine at the treatment with iodine suffered an oxidative cyclization yielding 3-aryl-4-(5-isoxazolyl)pyrazoles. 相似文献
97.
98.
M. P. Nosov V. A. Smirnova Yu. F. Zabashta A. Ya. Fridman M. P. Mokhnach 《Mechanics of Composite Materials》1989,25(1):8-12
Conclusion A method was proposed which makes it possible to study the low-frequency internal friction of complex fibers. This method was used to study the internal friction of complex composite fibers based on PCA and PE. We observed a relaxation process which is typical of the composite and is absent in the pure materials.Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 11–15, January–February, 1989. 相似文献
99.
激光晶体YAG中Er3+的辐射跃迁 总被引:2,自引:0,他引:2
本文讨论和分析了激光晶体YAG中Er3+离子的激光上能级的4S3/2、4I11/2和4I13/2辐射跃迁的有关因素。 相似文献
100.
D. B. Kayumova Yu. P. Syrnikov N. V. Penkina M. N. Rodnikova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(10):1634-1635
The structural relaxation time for series of various liquids (alkanes, aliphatic alcohols, and diols) are calculated from published data on the shear viscosity and the heat of evaporation per unit volume. Liquids having a 3D H-bond network (diols) are characterized by relaxation times one to two orders of magnitudes longer than those typical of liquids without such a network (alkanes and aliphatic alcohols). 相似文献