全文获取类型
收费全文 | 14258篇 |
免费 | 2626篇 |
国内免费 | 1694篇 |
专业分类
化学 | 11109篇 |
晶体学 | 263篇 |
力学 | 760篇 |
综合类 | 207篇 |
数学 | 1344篇 |
物理学 | 4895篇 |
出版年
2024年 | 44篇 |
2023年 | 308篇 |
2022年 | 483篇 |
2021年 | 585篇 |
2020年 | 778篇 |
2019年 | 711篇 |
2018年 | 599篇 |
2017年 | 557篇 |
2016年 | 827篇 |
2015年 | 890篇 |
2014年 | 991篇 |
2013年 | 1219篇 |
2012年 | 1334篇 |
2011年 | 1366篇 |
2010年 | 992篇 |
2009年 | 864篇 |
2008年 | 897篇 |
2007年 | 779篇 |
2006年 | 659篇 |
2005年 | 590篇 |
2004年 | 457篇 |
2003年 | 403篇 |
2002年 | 392篇 |
2001年 | 277篇 |
2000年 | 202篇 |
1999年 | 184篇 |
1998年 | 122篇 |
1997年 | 95篇 |
1996年 | 95篇 |
1995年 | 78篇 |
1994年 | 75篇 |
1993年 | 62篇 |
1992年 | 65篇 |
1991年 | 48篇 |
1990年 | 55篇 |
1989年 | 37篇 |
1988年 | 40篇 |
1987年 | 34篇 |
1986年 | 25篇 |
1985年 | 35篇 |
1984年 | 29篇 |
1983年 | 31篇 |
1982年 | 24篇 |
1981年 | 30篇 |
1980年 | 20篇 |
1979年 | 25篇 |
1978年 | 17篇 |
1977年 | 22篇 |
1974年 | 24篇 |
1972年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Fe2(CO)6(μ-S2) was used as a single source precursor in attempt to produce FeS film via MOCVD. Pyrolysis of Fe2(CO)6(μ-S2) at temperature below 500℃ produced Fe1-xS or Fe7S8 powder as indicated by its powder X-ray spectra. At 750 ℃, polycrystalline FeS powder was obtained. In film deposition, polycrystalline Fe1-xS or Fe7Ss films were obtained on Si(100) and Ag/Si(100) substrates below 500 ℃. SEM micrographs showed the film on Si(100) substrate containing whisker like grains. However, pillar like grains were obtained on Ag/Si(100) substrate.Deposition rates are also different for different substrates as evaluated by the thickness of the films, which were obtained by SEM micrographs of the cross section of the films. At 750℃, similar polycrystalline Fe1-xS or Fe7S8 film was obtained. 相似文献
32.
XiaoMinSUN DaChengFENG ZhengTingCAI 《中国化学快报》2004,15(6):749-752
For the Na I2 collision system, theoretical study is performed on the QCISD(T) level by using ab initio method. The ab initio potential energy surfaces are got and on them the long-lived complexes are found and optimized. These results verify the crossed molecule beam experimental phenomenon and the detailed geometry structures are given for the first time. The role of the complexes in the reaction path is also described in detail. 相似文献
33.
Direct Observation of Non-covalent Complexes for Phosphorylated Flavonoid-protein Interaction by ESI
XiaoLanCHEN TingZHANG HongXiaLIU LingBoQU YouZhuYU YuFenZHAO 《中国化学快报》2004,15(3):343-346
Diethyl flavon-7-yl phosphate was synthesized by modified Atheron-Todd reaction. The result of ESI shows that the phosphated flavonoids possess stronger binding affinities toward proteins such as myoglobin, insulin and lysozyme and are easier to form the non-covalent complexes with them. 相似文献
34.
合浦珠母贝(Pinctada martensii,Dunker)珍珠囊体外预培育的初步研究 总被引:1,自引:0,他引:1
0.3%胰蛋白酶液(25℃)消化外套膜组织的第5~15min时间段所收获的细胞产物中,表皮细胞具有最高的纯度和贴壁活性;细胞悬液的体外短期培养过程中小牛血清和珠母贝组织提取物对于细胞在体外的生长和在珠核表面的贴附具有促进作用. 相似文献
35.
B. Pignataro L. Chi S. Gao B. Anczykowski C. Niemeyer M. Adler H. Fuchs 《Applied Physics A: Materials Science & Processing》2002,74(3):447-452
Self-assembled oligomeric nanostructures consisting of bisbiotinylated DNA fragments connected by the protein streptavidin
(STV) are studied by dynamic scanning force microscopy (SFM) operating in air. A comparison of the images taken in repulsive
and attractive regimes is systematically made on DNA and STV structures. Stable and reproducible SFM images are obtained in
the attractive regime by using a special feedback circuit, called Q-control. On the other hand, when SFM is operating in the
repulsive regime, deformation of the structures that reduce the resolution and the image quality are clearly observable. The
heights of both DNA and STV have been measured as a function of the tip/molecule interaction forces. This study offers the
possibility to suggest a different mechanical behavior of DNA with respect to STV.
Received: 24 July 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献
36.
37.
A novel field emission pressure sensor has been achieved utilizing carbon nanotubes (CNTs) as the electron source. The sensor consists of the anode sensing film fabricated by wet etching process and multi-wall carbon nanotubes (MWNTs) cathode in the micro-vacuum chamber. MWNTs on the silicon substrate were grown by thermal CVD. The prototype pressure sensor has a measured sensitivity of about 0.17-0.77 nA/Pa (101-550 KPa). The work shows the potential use of CNTs-based field-emitter in microsensors, such as accelerometers and tactile sensors. 相似文献
38.
39.
The behavior of a two-level entangled atom in an optical field with circular polarization is studied in this paper. The interaction of an optical field and one of the entangled atoms is analyzed in detail. A general solution of the SchrAo¨Gdinger equation about the motion of the entangled atom is obtained. The properties of the action are dependent on the initial state of the atom. By detecting the entangled atom out of the field, we can obtain the state of the other atom moving in the field. It is shown that the state of the atom out of the field will influence the energies of the split-levels of the atom in the field. 相似文献
40.
In this note, we study convergence rates in the law of large numbers for independent and identically distributed random variables under sublinear expectations. We obtain a strong L^p-convergence version and a strongly quasi sure convergence version of the law of large numbers. 相似文献