全文获取类型
收费全文 | 1351篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
化学 | 910篇 |
晶体学 | 18篇 |
力学 | 27篇 |
数学 | 76篇 |
物理学 | 344篇 |
出版年
2019年 | 14篇 |
2018年 | 12篇 |
2016年 | 15篇 |
2015年 | 16篇 |
2014年 | 18篇 |
2013年 | 48篇 |
2012年 | 61篇 |
2011年 | 54篇 |
2010年 | 38篇 |
2009年 | 38篇 |
2008年 | 58篇 |
2007年 | 60篇 |
2006年 | 48篇 |
2005年 | 59篇 |
2004年 | 54篇 |
2003年 | 47篇 |
2002年 | 50篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 27篇 |
1998年 | 18篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 17篇 |
1994年 | 23篇 |
1993年 | 18篇 |
1992年 | 29篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 19篇 |
1987年 | 15篇 |
1986年 | 19篇 |
1985年 | 16篇 |
1984年 | 31篇 |
1983年 | 20篇 |
1982年 | 23篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 28篇 |
1977年 | 20篇 |
1976年 | 21篇 |
1975年 | 24篇 |
1974年 | 20篇 |
1973年 | 17篇 |
1972年 | 19篇 |
1971年 | 10篇 |
1969年 | 9篇 |
1966年 | 10篇 |
1965年 | 12篇 |
排序方式: 共有1375条查询结果,搜索用时 31 毫秒
1.
2.
Takayuki Yamanaka Hideki Fukano Ken Tsuzuki Munehisa Tamura Ryuzo Iga Matsuyuki Ogasawara Yasuhiro Kondo Tadashi Saitoh 《光学学报》2003,23(Z1)
A comprehensive analysis of multi-quantum-well electroabsorption modulators buried with semi-insulating (SI)-InP is presented. We quantitatively demonstrate that suppression of Zn diffusion into the burying and optical core layers plays a key role in high-speed and high-extinction operation. 相似文献
3.
Takuya Hasegawa Hirotaka Matsuura Kazumi Inagaki Hiroki Haraguchi 《Analytical sciences》2003,19(1):147-150
The major-to-ultratrace elements in human bone-marrow fluid were determined by ICP-AES (inductively coupled plasma atomic emission spectrometry), and ICP-MS (inductively coupled plasma mass spectrometry). The bone-marrow fluid sample was centrifuged prior to acid digestion to exclude the bone piece from bone marrow, and then digested with nitric acid. As a result, 20 elements could be determined over the concentration range from 1610 microg g(-1) for Na to 0.00043 microg g(-1) for W. It was found that Fe, Zn and Sb were enriched by ca. 264-, 7- and 15-fold, respectively, in bone-marrow fluid, compared to those in human blood serum. Alkali metals (K, Rb, Cs), except for Na, were also significantly enriched in bone-marrow fluid. Furthermore, the concentrations of various elements, such as Fe, P, Al, Zn, Cu, Se, Zr, Sn, Ag and W, were significantly higher than those in open seawater. 相似文献
4.
Kazumi Tsukada 《Geometriae Dedicata》1997,68(1):61-71
We investigate holomorphic maps between compact generalized Hopf manifolds (i.e., locally conformal Kähler manifolds with parallel Lee form). We show that they preserve the canonical foliations. Moreover, we study compact complex submanifolds of g.H. manifolds and holomorphic submersions from compact g.H. manifolds. 相似文献
5.
Michiko Tamura 《Geometriae Dedicata》1992,42(3):311-315
LetM be a complete smooth surface of constant mean curvature in the Euclidean 3-space. If there exists two helical geodesics onM through each point ofM, thenM is either a plane, a sphere, or a circular cylinder. 相似文献
6.
A relativistic Green function formalism has been applied to calculate layer-projected densities of states on Pd(110). In particular, we obtained unoccupied surface states and their dispersion relations along two directions in the surface Brillouin zone. Good agreement with recent inverse photoemission data is reached by using an energy-dependent dynamical surface potential barrier, which is based on a simple electron-plasmon interaction model, instead of a static surface barrier. 相似文献
7.
Tadao Seguchi Naoyuki Tamura 《Journal of polymer science. Part A, Polymer chemistry》1974,12(9):1953-1964
The regions trapping allyl radicals in irradiated polyethylene and the reactivity of the radicals with various monomers have been studied by electron spin resonance. Most of the allyl radicals are trapped in defects or surfaces of the crystallite, and only 10% of the radicals are trapped inside the crystallites. Since the reactivity of the allyl radicals depends on whether they come in contact with reactive monomers, the rate of reaction is related to the concentration of the monomers. When grafting reactions are initiated by allyl radicals, the rate of initiation is rapid and the rate of termination at the initial stage is also very fast. Consequently the yield of grafting increases at the initial stage but soon levels off, which is in contrast to the grafting behavior with alkyl radicals. 相似文献
8.
An interesting transformation occurs during acylation of 4(R)-hydroxymethyl-3-methyl-1,3-thiazolidine when 4(R)-acylthiomethyl-3-methyl-1,3-oxazolidines are yielded: the reaction competing with O-acylation is controlled by the bulkiness of the acyl group. 相似文献
9.
Y. Sakaiguchi T. Shikata H. Urakami A. Tamura H. Hirata 《Colloid and polymer science》1987,265(8):750-753
Some cationic surfactants such as cetyltrimethylammonium bromide (CTAB) show a very spectacular viscoelasticity in solution, in even very diluted states, with some aromatic substances added, such as salicylic acid. Formerly, the authors established that the remarkable solution behaviour was the result of the entanglement of such enormously elongated giant micelles, based on recognition of the existence of large aggregates, through direct observation of them as substantial images under the electron microscope.In this report, we further confirm the relation between micelle length and solution viscoelasticity after arbitrarily obtaining different size aggregates by altering the media pH, or by admixing shorter chain length surfactants than CTAB, which alone did not induce viscoelasticity. 相似文献
10.