全文获取类型
收费全文 | 22501篇 |
免费 | 5055篇 |
国内免费 | 7731篇 |
专业分类
化学 | 14258篇 |
晶体学 | 525篇 |
力学 | 1019篇 |
综合类 | 405篇 |
数学 | 1218篇 |
物理学 | 17862篇 |
出版年
2024年 | 231篇 |
2023年 | 823篇 |
2022年 | 1055篇 |
2021年 | 1037篇 |
2020年 | 764篇 |
2019年 | 859篇 |
2018年 | 534篇 |
2017年 | 839篇 |
2016年 | 939篇 |
2015年 | 1066篇 |
2014年 | 2070篇 |
2013年 | 1668篇 |
2012年 | 1481篇 |
2011年 | 1630篇 |
2010年 | 1397篇 |
2009年 | 1638篇 |
2008年 | 1839篇 |
2007年 | 1542篇 |
2006年 | 1448篇 |
2005年 | 1404篇 |
2004年 | 1361篇 |
2003年 | 1198篇 |
2002年 | 1090篇 |
2001年 | 971篇 |
2000年 | 764篇 |
1999年 | 672篇 |
1998年 | 631篇 |
1997年 | 675篇 |
1996年 | 644篇 |
1995年 | 570篇 |
1994年 | 456篇 |
1993年 | 380篇 |
1992年 | 407篇 |
1991年 | 353篇 |
1990年 | 332篇 |
1989年 | 279篇 |
1988年 | 114篇 |
1987年 | 64篇 |
1986年 | 22篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 14篇 |
1982年 | 7篇 |
1981年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
33.
Exact Solution of an Extended Hubbard Model with Electron—Lattice Interaction for an Organic Ferromagnetic Polymer 下载免费PDF全文
Using an exact diagonalization method,we study an extended Hubbard model with an electron-lattice interaction for an organic ferromagnetic chain with radical coupling.The result shows that the ferromagnetic ground state originates from the antiferromagnetic correlation between adjoining sites,which is enhanced by the on-site e-e repulsion.The intersite e-e repulsion induces the inhomogeneous distribution of the charge density.The dimerization is decreased by the e-e interaction and the radical coupling.The electron-lattice interaction and the radical coupling can transfer the spin density and charge density between the main chain and the radicals. 相似文献
34.
35.
Jing Cheng 《量子光学学报》2006,12(B08):71-72
The effect of finite control beam on the transverse spatial profile of the slow light propagation in an electromagnetically induced transparency medium is studied. From the second-order wave equation and linear response of an EIT medium to the signal field, we find it is possible to produce an effective waveguide for the signal field. The existence and properties of a set of localized, stationary transverse modes are demonstrated. Especially, by carefully manipulating the profile of the control beam, we can realize single-mode propagation for the signal field, which may be important for potential applications. 相似文献
36.
The solid-liquid interface motion of NaBi(WO4)2 (NBWO) melt crystal growth is observed in an in situ system, in which the whole processes of interface transition from fiat interface and cellular to dendrite are visualized. The spacing of the dendrite under smaller temperature gradient turns out to be larger than that under larger temperature gradient, which is found to be sensitive to the temperature distribution. The mechanism of dendrite growth of NBWO is studied based on the model of the growth units of anion coordination polyhedra. The { 001} face has two apex links, so it shows higher stability and has high growth rate and forms the arm of dendrite, whereas the {010} face has only one apex link, and thus shows relative slower growth rate and firstly forms the branches. 相似文献
37.
The photoionization of H atoms irradiated by few-cycle laser pulses is studied numerically. The variations of the total ionization, the partial ionizations in opposite directions, and the corresponding asymmetry with the carrier-envelope phase in several pulse durations are obtained. We find that besides a stronger modulation on the partial ionizations, the change of pulse duration leads to a shift along carrier-envelope (CE) phase in the calculated signals. The phase shift arises from the nonlinear property of ionization and relates closely to the Coulomb attraction of the parent ion to the ionized electron. Our calculations show good agreement with the experimental observation under similar conditions. 相似文献
38.
39.
线阵CCD在双棱镜测光波波长中的应用 总被引:1,自引:0,他引:1
CCD是一种以电荷量表示光量的大小,用耦合方式传输电荷量的新型光电传感器件,其基本部分由MOS光敏元列阵和读出移位寄存器组成.具有体积小、重量轻、功耗低、光谱响应范围宽、分辨率高、精度高、稳定性能良好等一系列优点,与计算机配合使用,使得由CCD采集到的大量数据的处理变得非常容易.对测量数据的处理可以经过存储、自动补偿和校正,最后打印输出,现今已在航天、遥感、军事设备、自动控制、雷达、医学、生物、化学、颜色测量等方面得到了广泛的应用[1].我们将其用在实验教学中,取得了很好的效果. 相似文献
40.