全文获取类型
收费全文 | 24130篇 |
免费 | 2958篇 |
国内免费 | 1915篇 |
专业分类
化学 | 17614篇 |
晶体学 | 276篇 |
力学 | 1043篇 |
综合类 | 97篇 |
数学 | 2180篇 |
物理学 | 7793篇 |
出版年
2024年 | 32篇 |
2023年 | 314篇 |
2022年 | 571篇 |
2021年 | 730篇 |
2020年 | 808篇 |
2019年 | 800篇 |
2018年 | 714篇 |
2017年 | 602篇 |
2016年 | 1019篇 |
2015年 | 958篇 |
2014年 | 1182篇 |
2013年 | 1747篇 |
2012年 | 2078篇 |
2011年 | 2145篇 |
2010年 | 1390篇 |
2009年 | 1317篇 |
2008年 | 1660篇 |
2007年 | 1510篇 |
2006年 | 1367篇 |
2005年 | 1233篇 |
2004年 | 1007篇 |
2003年 | 836篇 |
2002年 | 890篇 |
2001年 | 608篇 |
2000年 | 466篇 |
1999年 | 432篇 |
1998年 | 317篇 |
1997年 | 297篇 |
1996年 | 296篇 |
1995年 | 243篇 |
1994年 | 213篇 |
1993年 | 167篇 |
1992年 | 167篇 |
1991年 | 148篇 |
1990年 | 120篇 |
1989年 | 90篇 |
1988年 | 65篇 |
1987年 | 42篇 |
1986年 | 44篇 |
1985年 | 60篇 |
1984年 | 38篇 |
1983年 | 33篇 |
1982年 | 32篇 |
1981年 | 33篇 |
1980年 | 22篇 |
1979年 | 15篇 |
1978年 | 18篇 |
1976年 | 17篇 |
1975年 | 16篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 293 毫秒
111.
Hyunkook Park Machiko Tsukiji Kazuaki Wagatsuma SangChun Lee 《Analytical sciences》2007,23(9):1133-1136
The emission characteristics of several Cu lines emitted from a Ne-Ar mixed gas glow discharge plasma were investigated. The addition of small amounts of Ar to a Ne plasma increases the sputtering rate of a Cu sample because Ar ions, which work as the impinging ions for cathode sputtering, are predominantly produced through Penning ionization collisions between Ne metastables and Ar atoms. Ar addition also elevates the number density of electrons in the plasma. These changes occurring in the Ne-Ar mixed gas plasma result in enhanced emission intensities of the Cu lines. The Cu II 270.10-nm and the Cu II 224.70-nm lines yield different intensity dependence on the Ar partial pressure added. This phenomenon is because these Cu II lines are excited principally through different charge transfer processes: collisions with Ne ions for the Cu II 270.10-nm line and collisions with Ar ions for the Cu II 224.70-nm line. The shape of sputtered craters in the Ne-Ar glow discharge plasma was measured. The depth resolution was improved when Ar was added to a Ne plasma because the crater bottoms were flatter with larger Ar partial pressures. 相似文献
112.
A systematic study of the upper semicontinuity and the lower semicontinuity of the solution map in parametric affine variational
inequalities is given in this paper. Several examples are constructed to analyze the results.
This work was supported by Korea Research Foundation Grant (KRF 2001-015-DP0049), the APEC Postdoctoral Fellowships Program,
and the KOSEF Brain Pool Program. 相似文献
113.
Dong Hwan Choi Yoshio Katakura Rieko Matsuda Yuzuru Hayashi Masato Hirobe Yasuhiro Goda Kazuaki Ninomiya Suteaki Shioya 《Analytical sciences》2007,23(2):215-218
The mathematical model for predicting the precision, limit of detection (LOD) and range of quantitation (ROQ) in a competitive enzyme-linked immunosorbent assay (ELISA) proposed by Hayashi et al. (Anal. Chem., 2004, 76, 1295) was validated. The model describes the relative standard deviation (RSD) of concentration estimates by the RSDs of pipetting volumes of analyte, enzyme-conjugated antigen, antibody and substrate solutions, and the standard deviation (SD) of inherent absorbances between the wells in an ELISA plate. For 6 kinds of direct competitive ELISA kits, the LOD and ROQ predicted by the model agreed well with those obtained by experiments with real samples. It was also confirmed that the model is applicable to the prediction of uncertainty that depends on the pipetting error of the viscous antiserum solution. The model was demonstrated to be useful for estimating the LOD and ROQ of competitive ELISA. 相似文献
114.
115.
Yunshan Dong 《Applied Surface Science》2006,252(14):5057-5062
A series of Zr-Si-N composite films with different Si contents were synthesized in an Ar and N2 mixture atmosphere by the bi-target reactive magnetron sputtering method. These films’ composition, microstructure and mechanical properties were characterized by energy dispersive spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy and nanoindentation. Experimental results revealed that after the addition of silicon, Si3N4 interfacial phase formed on the surface of ZrN grains and prevented them from growing up. Zr-Si-N composite films were strengthened at low Si content with the hardness and elastic modulus reaching their maximum values of 29.8 and 352 GPa at 6.2 at% Si, respectively. With a further increase of Si content, the crystalline Zr-Si-N films gradually transformed into amorphous, accompanied with a remarkable fall of films’ mechanical properties. This limited enhancement of mechanical properties in the Zr-Si-N films may be due to the low wettability of Si3N4 on the surface of ZrN grains. 相似文献
116.
Yong-Goo Yoo Seong-Gi Min Ho-Jun Ryu Nam-Seok Park Seong-Cho Yu 《Journal of magnetism and magnetic materials》2006
Exchange biased IrMn/NiFe/IrMn thin films were studied as a function of NiFe thickness. In plane angular dependence of a resonance field distribution which is measured by FMR was analyzed as a combined effect of an unidirectional anisotropy and an uniaxial anisotropy. The unidirectional anisotropic field and the uniaxial anisotropic field were linearly varied with NiFe thickness while the films with a thicker NiFe layer do not follow the linear variation. Resonance field and linewidth variations were also analysed with NiFe thickness. 相似文献
117.
Xun Dong 《Discrete and Computational Geometry》2006,35(3):457-471
We prove that the bounded complex of an affine oriented matroid is
pure and collapsible. We also generalize Zaslavsky's central
decomposition theorem for hyperplane arrangements to affine
oriented matroids. 相似文献
118.
119.
In this paper, we find some new explicit examples of Hamiltonian minimal Lagrangian submanifolds among the Lagrangian isometric immersions of a real space form in a complex space form. 相似文献
120.
In this note, the authors resolve an evolutionary Wente's problem associated to heat equation, where the special integrability of det▽u for u ∈ H1(R2,R2) is used. 相似文献