全文获取类型
收费全文 | 32566篇 |
免费 | 3551篇 |
国内免费 | 6260篇 |
专业分类
化学 | 18021篇 |
晶体学 | 1069篇 |
力学 | 2250篇 |
综合类 | 868篇 |
数学 | 4081篇 |
物理学 | 16088篇 |
出版年
2024年 | 45篇 |
2023年 | 215篇 |
2022年 | 781篇 |
2021年 | 695篇 |
2020年 | 625篇 |
2019年 | 634篇 |
2018年 | 705篇 |
2017年 | 1042篇 |
2016年 | 867篇 |
2015年 | 988篇 |
2014年 | 1346篇 |
2013年 | 1982篇 |
2012年 | 2128篇 |
2011年 | 2537篇 |
2010年 | 2259篇 |
2009年 | 2259篇 |
2008年 | 2621篇 |
2007年 | 2398篇 |
2006年 | 2483篇 |
2005年 | 2105篇 |
2004年 | 1674篇 |
2003年 | 1247篇 |
2002年 | 1216篇 |
2001年 | 1731篇 |
2000年 | 1424篇 |
1999年 | 995篇 |
1998年 | 609篇 |
1997年 | 557篇 |
1996年 | 492篇 |
1995年 | 392篇 |
1994年 | 393篇 |
1993年 | 317篇 |
1992年 | 363篇 |
1991年 | 273篇 |
1990年 | 275篇 |
1989年 | 229篇 |
1988年 | 201篇 |
1987年 | 211篇 |
1986年 | 153篇 |
1985年 | 139篇 |
1984年 | 135篇 |
1983年 | 103篇 |
1982年 | 77篇 |
1981年 | 72篇 |
1980年 | 47篇 |
1979年 | 50篇 |
1978年 | 34篇 |
1977年 | 28篇 |
1976年 | 31篇 |
1975年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
31.
32.
基于密度泛函理论(DFT),用完全势能线性缀加平面波方法(FPLAPW)计算模拟了MnO2的同质多相变体(金红石型结构、CaCl2型结构、黄铁矿型结构),通过计算,预测了β-MnO2在5 GPa时从金红石型结构转变为CaCl2型结构,在20 GPa时进一步转变为黄铁矿型结构。另外,还总结和比较了几种金红石型结构二氧化物的压致相变特点,得出第Ⅳ主族元素的金红石型结构氧化物有很好的规律性,发生的相变序列基本一致;并随着金属阳离子半径的增大,发生相变的压力值也相应地递减,各氧化物的体积模量值相应地减小。 相似文献
33.
单甲基原位改性SiO2疏水减反膜的制备与性能研究 总被引:1,自引:0,他引:1
在碱性条件下通过TEOS和MTES的共水解缩聚反应制备了单甲基原位改性的SiO2溶胶,并使用提拉法在K9玻璃基片上镀制了疏水减反膜。通过透射电镜(TEM)考察了镀膜溶胶的微结构,分别使用红外光谱(FTIR)分析了薄膜的组分,用原子力显微镜(AFM)观察了薄膜的表面形貌和起伏状况,用紫外可见光谱(UV-vis)考察了薄膜的减反射性能,用接触角仪测量了薄膜对水的接触角。并使用“R-on-1”的方式测量了薄膜在Nd:YAG激光(1 064 nm,1 ns)作用下的损伤阈值。结果表明,通过共水解缩聚反应可以把甲基引入镀膜溶胶簇团中,改善了溶胶簇团的网络结构,使薄膜得到相当好的疏水性能和更好的抗激光损伤性能,同时薄膜能保持较好的减反射性能。 相似文献
34.
35.
36.
The results of laser induced deposition of copper on polyimide substrate from copper electrolyte solution are reported. Unlike most work reported in the literatures where CW Ar+ lasers were used, a second harmonic (532 nm wavelength) Q-switch Nd:YAG laser was used for our experiments. The deposition process was conducted by laser-catalyzing of the polyimide surface and subsequent photothermal-accelerated reduction of copper-complex ions in an alkaline reducing environment. The characteristics of the deposited copper line were investigated in terms of laser beam scanning speed, and the number of scans. The surface morphology and chemical composition of the deposited copper were analyzed using field emission scanning electron microscope (FESEM) and energy dispersive spectrometer (EDX). The optimum processing conditions have been identified. The copper deposit was found to adhere well to the substrate. 相似文献
37.
38.
WU Jian-Jun GAO Zi-You SUN Hui-Jun 《理论物理通讯》2006,46(7)
In this paper, based on the utility preferential attachment, we propose a new unified model to generate different network topologies such as scale-free, small-world and random networks. Moreover, a new network structure named super scale network is found, which has monopoly characteristic in our simulation experiments. Finally, the characteristics ofthis new network are given. 相似文献
39.
The orientation-selective growth of LaNiO3 films on Si(100) by pulsed laser deposition using a MgO buffer 总被引:4,自引:0,他引:4
X.Y. Chen K.H. Wong C.L. Mak J.M. Liu X.B. Yin M. Wang Z.G. Liu 《Applied Physics A: Materials Science & Processing》2002,75(4):545-549
Highly (100)-oriented, (110)-oriented and polycrystalline LaNiO3 (LNO) films were successfully prepared on Si(100) using an oriented MgO film as a buffer. It was somewhat surprising to find
that that the orientation relation between the LNO film and the corresponding MgO buffer was: LNO(100)\MgO(110), LNO(110)\MgO(111)
and LNO(polycrystalline)\MgO(100). The crystalline quality of the LNO films was shown to be sensitive to the preparation conditions
of the MgO buffer. The film surface was very smooth, without micrometer-sized droplets being observed. All LNO films were
of metallic conductivity, with a room-temperature resistivities of approximately 250, 280 and 420 μΩ cm for the (110)-oriented,
(100)-oriented and polycrystalline LNO, respectively.
Received: 2 April 2001 / Accepted: 23 October 2001 / Published online: 3 June 2002 相似文献
40.
Based on the Collins formula and irradiance moments definition, the propagation of the kurtosis parameter of super-Gaussian beams through a spherically aberrated lens is studied. Detailed numerical results are given. It is shown that, as compared with aberration-free super-Gaussian beams, the profile of spherically aberrated super-Gaussian beams can be leptokurtic, mesokurtic or platykurtic, depending on the aberration and propagation distance. The results for the spherically aberrated Gaussian beams can be dealt with as a special case treated in this paper. Finally, the advantage of our method is pointed out. 相似文献