全文获取类型
收费全文 | 13412篇 |
免费 | 2653篇 |
国内免费 | 2255篇 |
学科分类
数理化 | 18320篇 |
出版年
2024年 | 37篇 |
2023年 | 289篇 |
2022年 | 455篇 |
2021年 | 623篇 |
2020年 | 714篇 |
2019年 | 701篇 |
2018年 | 580篇 |
2017年 | 590篇 |
2016年 | 759篇 |
2015年 | 804篇 |
2014年 | 997篇 |
2013年 | 1236篇 |
2012年 | 1407篇 |
2011年 | 1445篇 |
2010年 | 1048篇 |
2009年 | 946篇 |
2008年 | 1074篇 |
2007年 | 847篇 |
2006年 | 744篇 |
2005年 | 566篇 |
2004年 | 460篇 |
2003年 | 327篇 |
2002年 | 271篇 |
2001年 | 220篇 |
2000年 | 191篇 |
1999年 | 178篇 |
1998年 | 124篇 |
1997年 | 89篇 |
1996年 | 112篇 |
1995年 | 74篇 |
1994年 | 74篇 |
1993年 | 66篇 |
1992年 | 50篇 |
1991年 | 51篇 |
1990年 | 30篇 |
1989年 | 32篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 27篇 |
1985年 | 18篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1959年 | 1篇 |
1957年 | 5篇 |
1937年 | 1篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
91.
Y. H. Zhang X. H. Zhou Q. Z. Zhao X. F. Sun X. G. Lei Y. X. Guo Z. Liu X. F. Chen Y. T. Zhu S. X. Wen G. J. Yuan X. A. Liu 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):335-336
High spin states of the odd-odd162Lu nucleus have been studied via147Sm(19F,4nγ)162Lu reaction at 95 MeV beam energy. Level scheme for yrast band based onπ[h11/2 v[i13/2] quasiparticle configuration was established up to I π = (23?) for the first time. This band shows the signature inversion in energy before backbending generally appeared in this mass region. It is stressed that the signature splitting in162Lu is larger than that in the160Tm nucleus. 相似文献
92.
93.
注入控制铜蒸气激光方向性时间过程测量 总被引:1,自引:0,他引:1
实验研究了注入控制对铜蒸气激光非稳腔输出光束质量的影响,从输出光发散角时间分辨过程的测量结果说明注入加速被注入腔内激光发散角的减小过程。由于被注入腔内放大自发辐射的存在,为得到较好的注入控制效果,注入光的脉宽和进入被注入腔的延时必须恰当。 相似文献
94.
95.
96.
97.
We reported controllable synthesis of ZnS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as
a polymer matrix. In a typical run, the appropriate amounts of zinc chloride (ZnCl2) and sodium sulfide (Na2S) in the presence of 2-mercaptoethanol (ME) as the organic ligand were well dispersed in H2O/dimethylformamide solution without any aggregation. In addition, the Mn-doped ZnS nanocrystals (NCs) were synthesized with
similar method. Then, ZnS-PMMA hybrids were obtained via free radical polymerization in situ by using ZnS NCs functionalized
with methacryloxypropyltrimethoxysilane (MPS). FT-IR characterization indicates the formation of robust bonding between ZnS
NCs and the organic ligand. The TEM images show that ZnS NCs are well dispersed in PMMA matrix, and particle size of as-prepared
ZnS NCs is about 2.6 nm, in agreement with the computing results of Brus’s model and Debye–Scherrer formula. The photoluminescence
measurements present that ZnS NCs, Mn-doped ZnS NCs, and ZnS/PMMA hybrid show good optical properties. 相似文献
98.
99.
Suoyuan Lian Lei Gao Zhenhui Kang Di Wu Yang Lan Lin Xu 《Solid State Communications》2004,132(6):375-378
Single-crystal magnetite nanowires with average diameter of ca. 20 nm and length of up to several micrometers were prepared by a simple alkaline surfactant-free hydrothermal process. The crystallinity, purity, morphology, and structural features of the as-prepared magnetite nanowires were investigated by powder X-ray diffraction, transmission electron microscopy (TEM) and selected area electron diffraction. The composition and length of nanowires depends on the pH, with higher pH favoring longer nanowires composed entirely of Fe3O4. A mechanism for nanowire growth is proposed. 相似文献
100.
THE NECESSARY AND SUFFICIENT CONDITIONS FOR THE SOLVABILITY OF A CLASS OF THE MATRIX INVERSE PROBLEM
Censider the solutions of the matrix inverse problem, which are symmetric positive semide finite on a subspace. Necessary and sufficient conditions for the solvability, as well as the general solution are obtained. The best approximate solution by the above solution set is given. Thus the open problem in [1] is solved. 相似文献