全文获取类型
收费全文 | 4451篇 |
免费 | 124篇 |
国内免费 | 18篇 |
专业分类
化学 | 3156篇 |
晶体学 | 47篇 |
力学 | 107篇 |
数学 | 204篇 |
物理学 | 1079篇 |
出版年
2022年 | 17篇 |
2021年 | 47篇 |
2020年 | 43篇 |
2019年 | 53篇 |
2018年 | 33篇 |
2017年 | 31篇 |
2016年 | 79篇 |
2015年 | 74篇 |
2014年 | 89篇 |
2013年 | 202篇 |
2012年 | 223篇 |
2011年 | 273篇 |
2010年 | 135篇 |
2009年 | 116篇 |
2008年 | 215篇 |
2007年 | 210篇 |
2006年 | 244篇 |
2005年 | 204篇 |
2004年 | 218篇 |
2003年 | 193篇 |
2002年 | 199篇 |
2001年 | 137篇 |
2000年 | 110篇 |
1999年 | 74篇 |
1998年 | 57篇 |
1997年 | 58篇 |
1996年 | 60篇 |
1995年 | 49篇 |
1994年 | 58篇 |
1993年 | 60篇 |
1992年 | 66篇 |
1991年 | 40篇 |
1990年 | 45篇 |
1989年 | 50篇 |
1988年 | 45篇 |
1987年 | 42篇 |
1986年 | 43篇 |
1985年 | 87篇 |
1984年 | 82篇 |
1983年 | 31篇 |
1982年 | 39篇 |
1981年 | 36篇 |
1980年 | 40篇 |
1979年 | 65篇 |
1978年 | 50篇 |
1977年 | 56篇 |
1976年 | 48篇 |
1975年 | 31篇 |
1974年 | 24篇 |
1973年 | 18篇 |
排序方式: 共有4593条查询结果,搜索用时 31 毫秒
11.
Yukio Iida Masahiro Shibutani Katsuhiko Kobayashi Kazuhiko Ohnuma Yoichi Miyake Toru Noda 《Optical Review》2006,13(2):87-92
The double-pass method is thought to obtain the point spread function (PSF) in human eyes based on two techniques: the symmetric
double-pass method using the same pupil size and the asymmetric double-pass method using a different pupil size. The symmetric
double-pass method provides autocorrelation of the retinal PSF and, thus, the modulation transfer function. The asymmetric
double-pass method provides low-frequency partial-phase information and the partial phase-retrieval algorithm is applied to
obtain the complete-phase information, and to estimate the PSF. The partial phase-retrieval algorithm is based on the iteration
method proposed by Fineup and Kowalczyk and requires a lengthy computation. In this study, we propose a new high-speed phase-retrieval
algorithm based on the property that the real and imaginary parts of optical transfer functions (OTFs) continuously change
in value. 相似文献
12.
13.
14.
15.
Kobayashi H. Satou Y. Okuno Y. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2002,30(6):2152-2159
In an magnetohydrodynamic (MHD) generator using a frozen inert gas plasma (FIP), the availability of a frozen argon plasma, the influence of plasma uniformity at the generator inlet on the performance, and the feasibility of a large-scale generator are numerically examined by /spl gamma/-/spl theta/ two-dimensional simulation. The FIP is produced by pre-ionizing inert gas without an alkali metal seed at the generator inlet, then the ionization degree of the plasma is kept almost constant in the whole of the channel because of considerable slow recombination of the inert gas just like frozen reaction plasma. It is found that not only helium, but also argon frozen plasma MHD generation is realized, although highly accurate control of inlet ionization degree is necessary for argon. It is important to reduce the nonuniformity of plasma properties at the generator inlet in order to raise the maximum enthalpy extraction ratio. Even for the large-scale generator with 1000-MW thermal input, the ionization degree is kept almost constant in the whole of the channel and the high performance is obtainable. This result is extremely attractive for the FIP MHD generator. 相似文献
16.
Y. Fukuda T. Kobayashi H. Yoshida T. Sekizawa N. Sanada 《Applied Surface Science》2002,190(1-4):279-283
Adsorption and decomposition of triethylindium (TEI: (C2H5)3In) on a GaP(0 0 1)-(2×1) surface have been studied by low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). It is found from the TPD result that ethyl radical and ethylene are evolved at about 300–400 and 450–550 K, respectively, as decomposition products of TEI on the surface. This result is quite different from that on the GaP(0 0 1)-(2×4) surface. The activation energy of desorption of ethyl radical is estimated to be about 93 kJ/mol. It is suggested that TEI is adsorbed molecularly on the surface at 100 K and that some of TEI molecules are dissociated into C2H5 to form P–C2H5 bonds at 300 K. The vibration modes related to ethyl group are decreased in intensity at about 300–400 and 450–550 K, which is consistent with the TPD result. The TEI molecules (including mono- and di-ethylindium) are not evolved from the surface. Based on the TPD and HREELS results, the decomposition mechanism of TEI on the GaP(0 0 1)-(2×1) surface is discussed and compared with that on the (2×4) surface. 相似文献
17.
Midori Kobayashi Hitoshi Awoki Yoshimi Nakazaki Gisaku Nakamura 《Graphs and Combinatorics》1989,5(1):243-244
In this paper, a perfect one-factorization ofK
36 is given, which is factor-1-rotational. 相似文献
18.
Osamu Kobayashi 《Mathematische Zeitschrift》1989,200(2):273-277
Financial support from the FRD is gratefully acknowledged 相似文献
19.
Analysis of Spectral Reflectance Using Normalization Method from Endoscopic Spectroscopy System 总被引:2,自引:0,他引:2
Masao Sambongi Makoto Igarashi Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama Masahiko Kobayashi Yasushi Sano Shigeaki Yoshida Kazuhiro Gono 《Optical Review》2002,9(6):238-243
Objective assessment of gastrointestinal mucosal color is extremely important in the endoscopic diagnosis of digestive tract disease. In this paper, we propose a method to clarify the spectral characteristics of gastric and colon cancer. A large number of spectral reflectance data of mucous membrane are measured by the endoscopic spectroscopy system (ESS) in the National Cancer Center Hospital East, Kashiwa, Japan and the Department of Internal Medicine, Self-Defense Force Center Hospital, Tokyo, Japan. We assume that early cancer appears primarily in the spectral data of short wavelength, because it is usually present in a superficial cell where short wavelength light is scattered more strongly than long wavelength light. To identify the features in the short wavelength components, the spectral reflectance was divided by the reflectance of a long wavelength. We investigated the possibility of distinguishing early cancer from normal spectral data through statistical analysis, employing the projection axis as the mean difference between them. Early cancer and normal spectral data were projected on the projection axis, and the Student’s T-test was applied to evaluate the mean of the distribution between these data. 相似文献
20.
Toshiyuki Kobayashi 《Mathematische Annalen》1989,285(2):249-263
Partially supported by Grant-in-Aid for Scientific Research (No. 63740074) 相似文献