全文获取类型
收费全文 | 54250篇 |
免费 | 8618篇 |
国内免费 | 11586篇 |
专业分类
化学 | 38882篇 |
晶体学 | 1104篇 |
力学 | 3683篇 |
综合类 | 947篇 |
数学 | 7467篇 |
物理学 | 22371篇 |
出版年
2024年 | 155篇 |
2023年 | 759篇 |
2022年 | 1601篇 |
2021年 | 1599篇 |
2020年 | 1793篇 |
2019年 | 1790篇 |
2018年 | 1520篇 |
2017年 | 1702篇 |
2016年 | 2122篇 |
2015年 | 2300篇 |
2014年 | 2812篇 |
2013年 | 3671篇 |
2012年 | 3978篇 |
2011年 | 5159篇 |
2010年 | 3870篇 |
2009年 | 3867篇 |
2008年 | 3735篇 |
2007年 | 3459篇 |
2006年 | 3234篇 |
2005年 | 3142篇 |
2004年 | 3218篇 |
2003年 | 2463篇 |
2002年 | 2509篇 |
2001年 | 2209篇 |
2000年 | 1686篇 |
1999年 | 1278篇 |
1998年 | 1015篇 |
1997年 | 829篇 |
1996年 | 774篇 |
1995年 | 658篇 |
1994年 | 634篇 |
1993年 | 873篇 |
1992年 | 891篇 |
1991年 | 657篇 |
1990年 | 584篇 |
1989年 | 594篇 |
1988年 | 260篇 |
1987年 | 155篇 |
1986年 | 159篇 |
1985年 | 145篇 |
1984年 | 127篇 |
1983年 | 108篇 |
1982年 | 87篇 |
1981年 | 46篇 |
1980年 | 44篇 |
1979年 | 27篇 |
1978年 | 22篇 |
1977年 | 26篇 |
1976年 | 15篇 |
1974年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Wuqing Ning 《Journal of Mathematical Analysis and Applications》2007,327(2):1396-1419
In this paper, an algorithm is established to reconstruct an eigenvalue problem from the given data satisfying certain conditions. These conditions are proved to be not only necessary but also sufficient for the given data to coincide with the spectral characteristics corresponding to the reconstructed eigenvalue problem. 相似文献
92.
吴臻 《数学物理学报(B辑英文版)》2004,24(1):91-99
The existence and uniqueness results of fully coupled forward-backward stochastic differential equations with stopping time (unbounded) is obtained. One kind of comparison theorem for this kind of equations is also proved. 相似文献
93.
94.
Qing Shi Dong Yang Yanlei Su Jian Li Zhongyi Jiang Yanjun Jiang Weikang Yuan 《Journal of nanoparticle research》2007,9(6):1205-1210
Lipase from Candida rugosa was covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a self-catalytic mechanism. A variety
of characterization techniques including FTIR, Raman spectroscopy, and XPS were employed to demonstrate the formation of the
ester linkage between lipase and MWNTs. The MWNTs-lipase biocomposites showed significantly increased solubility in some common-used
organic solvents, such as THF, DMF and chloroform. This study may offer a novel and facile route for covalent modification
of carbon nanotubes, and expand the potential utilization of both lipases and MWNTs in the fields of biocatalyst and biosensor. 相似文献
95.
The main aim of this paper is to provide convergence analysis of Quasi-Wilson nonconforming finite element to Maxwell's equations under arbitrary quadrilateral meshes.The error estimates are derived,which are the same as those for conforming elements under conventional regular meshes. 相似文献
96.
97.
CAI Guang-Yu LlU Zhong-Min SHI Ren-Min HE Chang-Qing YANG Li-Xin SUN Cheng-LinDalian Institute of Chemical Physics Acadernia Sinica Dalian Iiaorting 《天然气化学杂志》1995,(2)
A new route named as SDTO method for the synthesis of lightolefins from syngas has been proposed.That is to convert syngas todimethylether and then to convert dimethylether to light olefins.The catalystsfor the two conversion reactions have been developed.For the first reaction,the catulySt was synthesized by the combination of methanol synthesis catalystwith γ-Al_2O_3or zeolites which possesses both metallic and acidic functions.Thecatalyst for the second reaction was modified SAPO-34 molecular sieve.Thevariables of the reactions have also been investigated.The results from theserial connection of the two conversion steps without any separation show thatthe yield of C_2~-C_4~- olefins Could be>100g/(m~3 syngas). 相似文献
98.
Hua Jin Zhuangqi Hu Qingmin Liu Yunlong Ge Changxu Shi 《Applied Physics A: Materials Science & Processing》1992,54(5):399-403
A crystallization study has been carried out for rapidly solidified Bi2Pb0.5Sr2Ca4Cu5Ox glass. Glass transition temperature T
g, crystallized superconducting phases and microstructural changes were measured and analysed by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The crystallization mechanism of the three superconducting phases — (2201) 20 K phase, (2212) 80 K phase, and (2223) 110 K phase — has been discussed, and a time-temperature-transformation diagram for the glass has been constructed. 相似文献
99.
100.
超软X射线流气式正比计数管 总被引:2,自引:0,他引:2
介绍了一种用于测量183~933eV超软X射线的圆柱形、侧窗式、流气式正比计数管,工作气体是0.11MPa的P-10气体或氦气-丙烷混合气体。计数管内径为φ25mm,直径为φ0.3mm的入射窗是由厚度80~90μgcm~2聚乙烯甲醛制成的。该计数管的特点:(1)薄窗,对软X射线透过率高。(2)流气式,工作寿命长。(3)能量分辨率好。(4)计数率高(1×10~(14)个/s)。(5)可测能区宽(0.183~10keV)。(6)可以方便更换窗膜材料、厚度及窗口直径。近几年来该计数管已经为高强度低能X光源提供较好监测。 相似文献