全文获取类型
收费全文 | 7127篇 |
免费 | 231篇 |
国内免费 | 29篇 |
专业分类
化学 | 5494篇 |
晶体学 | 87篇 |
力学 | 122篇 |
数学 | 567篇 |
物理学 | 1117篇 |
出版年
2022年 | 45篇 |
2021年 | 58篇 |
2020年 | 82篇 |
2019年 | 101篇 |
2018年 | 65篇 |
2017年 | 45篇 |
2016年 | 124篇 |
2015年 | 121篇 |
2014年 | 159篇 |
2013年 | 344篇 |
2012年 | 383篇 |
2011年 | 426篇 |
2010年 | 235篇 |
2009年 | 235篇 |
2008年 | 455篇 |
2007年 | 466篇 |
2006年 | 464篇 |
2005年 | 394篇 |
2004年 | 358篇 |
2003年 | 329篇 |
2002年 | 299篇 |
2001年 | 113篇 |
2000年 | 102篇 |
1999年 | 82篇 |
1998年 | 61篇 |
1997年 | 92篇 |
1996年 | 95篇 |
1995年 | 48篇 |
1994年 | 65篇 |
1993年 | 63篇 |
1992年 | 63篇 |
1991年 | 64篇 |
1990年 | 38篇 |
1989年 | 43篇 |
1988年 | 52篇 |
1987年 | 44篇 |
1986年 | 42篇 |
1985年 | 87篇 |
1984年 | 100篇 |
1983年 | 52篇 |
1982年 | 91篇 |
1981年 | 87篇 |
1980年 | 76篇 |
1979年 | 77篇 |
1978年 | 82篇 |
1977年 | 64篇 |
1976年 | 67篇 |
1975年 | 48篇 |
1974年 | 52篇 |
1973年 | 69篇 |
排序方式: 共有7387条查询结果,搜索用时 281 毫秒
991.
992.
993.
994.
Yasuyo Maezawa Yoichiroh Hosokawa Kazunori Okano Mie Matsubara Hiroshi Masuhara 《Applied Physics A: Materials Science & Processing》2010,101(1):127-131
When a stress wave generated by focusing a femtosecond laser is loaded on an animal cell adhered on a substrate, the cell
is detached from the substrate. There are two possible mechanisms for the cell detachment: (a) The cell is detached from a
scaffold coated on a glass plate, and (b) the cell is detached from the glass plate with the scaffold. In this work, we have
studied the cell-detachment mechanism by visualizing the scaffold with a fluorescence probe of quantum dots. When the cell
was detached from the substrate, fluorescence from the scaffold simultaneously disappeared from the glass plate, although
the scaffold was not irradiated by the laser. This indicates that detachment due to the stress wave is attributed to mechanism (a).
On the other hand, when the cell was detached from the substrate by a trypsin treatment, the fluorescence from the scaffold
remained, suggesting mechanism (b). By comparing both results, it is considered that physiological damage of the cell membrane
during the detachment process by femtosecond laser-induced stress wave is less than that due to the trypsin treatment. 相似文献
995.
996.
Hisashi Yoshida Akinori Okamoto Seigi Mizuno Hiroshi Tochihara 《Surface science》2010,604(5-6):535-540
Low-energy electron diffraction (LEED) have been used to determine the Cu(0 0 1)–c(4 × 4)-Sn structure formed at 300 K. It is demonstrated that a structural model suggested by scanning tunneling microscopy observations is correct: The model consists of one substitutional Sn atom and four Sn adatoms in the unit cell. Optimum parameters of the determined c(4 × 4) structure reveal that Sn adatoms laterally are displaced by 0.30 Å away from ideal fourfold-hollow sites along the 〈100〉 directions. It is proposed that such displacements of the Sn adatoms cause the formation of a network of octagonal rings on Cu(0 0 1). The substitutional Sn atom is located at each center of the octagonal rings. The formation conditions of the network are discussed. 相似文献
997.
A TiO2(1 1 0)-(1 × 1) surface was prepared in an ultra-high vacuum, transported in laboratory air, and observed with a scanning tunneling microscope (STM) operated in a vacuum of 10−4 Pa. Empty state images showed atomically flat terraces separated by single-height steps, on which 5-fold-coordinated surface Ti atoms were observed as spots arranged in a rectangular lattice. The Ru(4,4′-dicarboxy-2,2′-bipyridine)2(NCS)2 (N3) dye was adsorbed on the TiO2 surface by immersing the TiO2 wafer into an acetonitrile solution of the dye. In the empty state images, individual N3 molecules were observed as oval particles protruding by 0.6 nm from the TiO2 surface. The oval shape elongated to the [1 0] directions was attributed to electron tunneling from tip to unoccupied states localized at the two carboxyl groups bound to the TiO2 surface. 相似文献
998.
Tokiyoshi Matsuda Mamoru Furuta Takahiro Hiramatsu Hiroshi Furuta Chaoyang Li Takashi Hirao 《Applied Surface Science》2010,256(21):6350-2485
Thermal stability of sputter deposited ZnO thin films was evaluated by thermal desorption spectroscopy (TDS). Desorption of Zn was mainly observed from the films deposited at low O2/Ar gas ratio and low RF power. In contrast, O2 desorption was mainly observed from the films deposited at high O2/Ar gas ratio and high RF power. The amount of desorbed O2 from the film increased with increasing the O2/Ar gas flow ratio and the RF power. Furthermore, the desorption temperature of O2 increased with increasing the RF power during the deposition. Thermal stability of the ZnO films was controlled not only by the O2/Ar gas flow ratio, but also applied RF power to the target. 相似文献
999.
1000.
Michiya Kobayashi Hiroshi Yabe 《Journal of Computational and Applied Mathematics》2010,234(2):375-397
In this paper, we deal with conjugate gradient methods for solving nonlinear least squares problems. Several Newton-like methods have been studied for solving nonlinear least squares problems, which include the Gauss-Newton method, the Levenberg-Marquardt method and the structured quasi-Newton methods. On the other hand, conjugate gradient methods are appealing for general large-scale nonlinear optimization problems. By combining the structured secant condition and the idea of Dai and Liao (2001) [20], the present paper proposes conjugate gradient methods that make use of the structure of the Hessian of the objective function of nonlinear least squares problems. The proposed methods are shown to be globally convergent under some assumptions. Finally, some numerical results are given. 相似文献