全文获取类型
收费全文 | 9679篇 |
免费 | 751篇 |
国内免费 | 421篇 |
专业分类
化学 | 6016篇 |
晶体学 | 90篇 |
力学 | 413篇 |
综合类 | 45篇 |
数学 | 1954篇 |
物理学 | 2333篇 |
出版年
2023年 | 122篇 |
2022年 | 202篇 |
2021年 | 296篇 |
2020年 | 307篇 |
2019年 | 345篇 |
2018年 | 322篇 |
2017年 | 291篇 |
2016年 | 435篇 |
2015年 | 359篇 |
2014年 | 509篇 |
2013年 | 689篇 |
2012年 | 713篇 |
2011年 | 716篇 |
2010年 | 448篇 |
2009年 | 444篇 |
2008年 | 544篇 |
2007年 | 457篇 |
2006年 | 404篇 |
2005年 | 338篇 |
2004年 | 307篇 |
2003年 | 245篇 |
2002年 | 271篇 |
2001年 | 223篇 |
2000年 | 153篇 |
1999年 | 120篇 |
1998年 | 107篇 |
1997年 | 81篇 |
1996年 | 104篇 |
1995年 | 91篇 |
1994年 | 91篇 |
1993年 | 89篇 |
1992年 | 79篇 |
1991年 | 85篇 |
1990年 | 69篇 |
1989年 | 46篇 |
1988年 | 52篇 |
1987年 | 61篇 |
1986年 | 53篇 |
1985年 | 59篇 |
1984年 | 50篇 |
1983年 | 33篇 |
1982年 | 58篇 |
1981年 | 49篇 |
1980年 | 41篇 |
1979年 | 57篇 |
1978年 | 38篇 |
1977年 | 35篇 |
1976年 | 35篇 |
1975年 | 29篇 |
1974年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
952.
Improvements of a method for measurement of continuous displacements and deformations with digital phase shifting speckle pattern interferometry are presented. The method is based on an algorithm that, with the knowledge of the initial phase, only needs one image at a time to evaluate continuos phase changes due to object deformations. In the improved method, the initial random phase of the speckle pattern is evaluated using a number of phase-shifted images before the deformation under study. This is used for increasing the accuracy of the initial phase estimation and reducing influences from image noise and other measurement disturbances. The phase-shifted speckle patterns are used as references for comparison with the speckle patterns of the deformed object, thereby increasing the reliability and accuracy of the phase estimations of the deformed patterns. The technique can be used for measuring deformations such as transients and other dynamic events, heat expansion as well as other phenomena where it is difficult to accomplish phase shifting during deformation. 相似文献
953.
In this paper we establish some implicit function theorems for a class of locally Lipschitz set-valued maps and then apply them to investigate some questions concerning the stability of optimization problems with inclusion constraints. In consequence we have an extension of some of the corresponding results of Robinson, Aubin, and others. 相似文献
954.
Nguyen To Nhu Jose M. R. Sanjurjo Tran Van An 《Proceedings of the American Mathematical Society》1997,125(10):3089-3098
In this second part of our paper, we apply the result of Part 1 to show that the compact convex set with no extreme points, constructed by Roberts (1977), is an AR.
955.
Nguyen Buong 《Ukrainian Mathematical Journal》1997,49(5):697-707
The purpose of this paper is to investigate an operator version of Tikhonov regularization for a class of ill-posed variational
inequalities under arbitrary perturbation operators. Aspects of convergence rate and finite-dimensional approximations are
considered. An example in the theory of generalized eigenvectors is given for illustration.
Institute of Information Technology, Vietnam. Published in Ukrainskii Matematicheskii Zhunal, Vol. 49, No. 5, pp. 629–637,
May, 1997. 相似文献
956.
基于遗传算法的静态Ad-hoc拓扑结构控制 总被引:2,自引:0,他引:2
将遗传算法引入到了静态Ad—hoc无线网络的拓扑结构控制中,突破了网络中所有节点辐射半径都相同的固有思路,通过调节各无线节点的辐射半径,在相邻节点对之间形成有向路径,从而达到节省节点能源消耗和网络拓扑结构优化的目的,并取得了较好的实验结果。 相似文献
957.
New, bent-core, polycatenar pyridine mesogens are described. Binding to silver(I) leads to complexes properly described as discotic. 相似文献
958.
K.M. Lee K.W. Cheah B.L. An M.L. Gong Y.L. Liu 《Applied Physics A: Materials Science & Processing》2005,80(2):337-339
A white-light light-emitting diode (LED) was successfully fabricated by converting near-UV LED emission (390–420 nm) with a new inorganic/organic hybrid phosphor. This new white-light phosphor consisted of three fluorescence materials; two strontium aluminates based with lanthanide oxides, SrAl2O4:Eu2+ (for green (520 nm) emission) and Sr4Al14O25:Eu2+ (for blue (490 nm) emission) and a new organic Eu metal complex, Eu(BTFA)3phen (for red (614 nm) emission). These materials have good absorption in the 300–500-nm range and have high quantum efficiencies (4.7–24.5%). The white phosphor has a CIE value of (0.321, 0.365). PACS 42.70.-aj; 78.40.-q; 78.55.-m; 81.05.Lg 相似文献
959.
The domain structures in NiFe elements were studied by magnetic force microscopy measurement and micromagnetic modeling. The remanent states in the elements were dependent on the direction of the saturation field. The “S” and “U” states were observed at remanence by applying the saturation field at different directions. The “S” and “U” states are metastable: magnetic force microscopy tip field-induced switching from the “S” and “U” states to the flux closure configuration was observed. 相似文献
960.
本文合成了四种新配合物:二氯化双苯甲醛缩氮基硫脲合铜(Ⅱ)(Cu~Ⅱ(Betsc—H)_2Cl_2),三氯化水杨醛缩氨基硫脲合铁(Ⅲ)(Fe~Ⅲ(Satsc—H_2)Cl_3,二氯化双对二甲氨基苯甲醛缩氨基硫脲合钴(Ⅱ)(Co~Ⅱ(Dmabtsc—H)_2Cl_2·H_2O)及双对硝基苯甲醛缩氨基硫脲合钴(Ⅱ)醋酸盐(Co~Ⅱ(Nitsc—H)(Nitsc)(Ac))。用元素分析和IR测定了化合物的组成,并进行了吸放O_2和CO的试验。 相似文献