全文获取类型
收费全文 | 461篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
化学 | 342篇 |
晶体学 | 7篇 |
力学 | 5篇 |
数学 | 18篇 |
物理学 | 98篇 |
出版年
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 35篇 |
2012年 | 18篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 24篇 |
2007年 | 29篇 |
2006年 | 25篇 |
2005年 | 29篇 |
2004年 | 24篇 |
2003年 | 28篇 |
2002年 | 26篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有470条查询结果,搜索用时 109 毫秒
51.
M. Koizumi T. T. Inamura K. Morita M. Takami M. Wakasugi A. Yoshida M. Azuma H. Katsuragawa T. Horiguchi T. Ishizuka I. Nakamura M. Nakaoka A. Iivonen K. Valli S. Matsuki T. Murayama K. Shimomura T. Shinozuka I. Sugai Y. Tagishi 《Hyperfine Interactions》1992,74(1-4):181-191
We have constructed a fast atomic-beam collinear laser spectroscopy system connected to the on-line isotope separator facility
GARIS/IGISOL at RIKEN. This system is potentially powerful in studying refractory elements. To test the system, an off-line
collinear experiment was made on stable Hf isotopes produced by means of laser ablation technique. For production of radioactive
Hf isotopes, the use of the inverse kinematics of a fusion reaction,9Be(166Er,xn)175-x
Hf, was investigated. The radioactive isotope169Hf was successfully extracted from GARIS/IGISOL and accelerated up to 30 keV. 相似文献
52.
We studied, experimentally, the pattern dynamics and free surface deformation in Bénard–Marangoni convection, in a circular
container (aspect ratio = 6). The free surface deformation fields were visualized by interferometry and temperature fields
by infrared thermography. We considered the influence of the Marangoni (up to 2,623), Biot and Prandtl numbers. More dynamics
are induced by increasing the Biot number and transition to a time-dependent flow has been observed. Conversely, increasing
the Prandtl number reduces the dynamics. The deformation increases as a function of the Marangoni number until it reaches
asymptotic values, which are functions of the Biot and Prandtl numbers. 相似文献
53.
Fujimoto H Ogawa K Takarabe K Udono H Sugiyama H Azuma J Takahashi K Kamada M 《Dalton transactions (Cambridge, England : 2003)》2011,40(22):6023-6027
Resonant and constant-initial state photoemission spectroscopies using synchrotron radiation were applied to investigate the valence-band electronic structure of a semi-conducting β-type iron-disilicide (β-FeSi(2)) thin film. The results clearly indicated that the component elements, iron (Fe) and silicon (Si), contribute differently to the valence band features; the Fe 3d orbitals mainly concentrate in the top region of the valence band while the Si 3s and 3p orbitals spread over the wide region of the valence band. The β-FeSi(2) thin film showed a typical p-type semi-conducting nature with a work function of 4.78 eV. The β-FeSi(2) film showed the Fe M(1)VV Auger lines around the kinetic energy of 88 eV. It would be expected from these observations that there exist strong interactions between iron and silicon atoms in the β-FeSi(2) film resulting in orbital mixing and band formation. 相似文献
54.
A convenient synthesis of indole triflones is reported. N-Alkyl, aryl and N-H indole triflones were obtained in 82-96% yields by the Tf(2)O/TTBP System. Biindolyl triflones were accessed in 51-81% yields for the first time by simple treatment of the resulting indole triflones with a base and without any use of organometallic chemistry. An environmentally friendly solvent, Solkane 365/227, can be substituted for this process without any loss of efficiency. 相似文献
55.
We establish the Bäcklund transformation for the construction of time-like surfaces with positive Gaussian curvature and imaginary principal curvatures. The construction can be realized by algebraic algorithm via Darboux transformations. 相似文献
56.
Keisuke Yoshiki Hiroki Azuma Kazuhiko Yoshioka Mamoru Hashimoto Tsutomu Araki 《Optical Review》2005,12(5):415-419
We have investigated the fluorescence lifetime properties of 8 calcium ion probes, calcium-green-1, calcium green-2, calcium
green-5N, calcium orange, oregon green 488 BAPTA-6F, fluo-3, fluo-4, and fluo-5N. We found that the decay time of calcium
green-5N varied more sensitively with calcium concentration than calcium green-1 which was known to be a highly sensitive
probe. We have also found that the center of observable range of calcium concentration by fluorescence lifetime measurement
is lower than that by fluorescence intensity measurement. 相似文献
57.
58.
Koichiro Yonetake Kunio Maruyama Jun-Ichi Sugiyama Toru Masuko Mitsuru Ueda 《Journal of polymer science. Part A, Polymer chemistry》1994,32(8):1415-1421
Poly[4-(4-hydroxyphenoxy) benzoic acid] was prepared by the bulk polycondensation of 4-(4-acetoxyphenoxy) benzoic acid. Polycondensation was conducted at 350°C for 3 h under a reduced pressure of 0.1 mmHg and gave a polymer with X?n of 255. The polymer was characterized by elemental analysis, IR spectroscopy, differential scanning calorimetry, and wide-angle X-ray measurement. The crystal/nematic and nematic/isotropic phase transition temperatures of polymer, which depend on the molecular weight, were observed at about 300°C and 410°C, respectively. The polymers with low molecular weights showed nematic textures above 300°C. This nematic/isotropic phase transition temperature is lower than that of poly (4-hydroxybenzoic acid). This thermal behavior of polymer comes from ether units, which increase the flexibility (the rotation or torsion of skeletal bonds) of the polymer chain. © 1994 John Wiley & Sons, Inc. 相似文献
59.
60.
Such an asymmetric [2,3]-Wittig variant that is both highly enantio- and erythro-selective is described within the context of the chiral synthesis of the insect pheromones, (3, 4)-4-methyl-3-heptanol and ()-4-methyl-3-heptanone. 相似文献