全文获取类型
收费全文 | 6412篇 |
免费 | 185篇 |
国内免费 | 25篇 |
专业分类
化学 | 4546篇 |
晶体学 | 79篇 |
力学 | 79篇 |
数学 | 293篇 |
物理学 | 1625篇 |
出版年
2022年 | 27篇 |
2021年 | 44篇 |
2020年 | 67篇 |
2019年 | 82篇 |
2018年 | 64篇 |
2017年 | 53篇 |
2016年 | 107篇 |
2015年 | 109篇 |
2014年 | 146篇 |
2013年 | 321篇 |
2012年 | 300篇 |
2011年 | 355篇 |
2010年 | 190篇 |
2009年 | 189篇 |
2008年 | 364篇 |
2007年 | 303篇 |
2006年 | 326篇 |
2005年 | 313篇 |
2004年 | 306篇 |
2003年 | 244篇 |
2002年 | 267篇 |
2001年 | 160篇 |
2000年 | 174篇 |
1999年 | 97篇 |
1998年 | 72篇 |
1997年 | 73篇 |
1996年 | 77篇 |
1995年 | 48篇 |
1994年 | 69篇 |
1993年 | 93篇 |
1992年 | 95篇 |
1991年 | 81篇 |
1990年 | 69篇 |
1989年 | 58篇 |
1988年 | 78篇 |
1987年 | 75篇 |
1986年 | 76篇 |
1985年 | 114篇 |
1984年 | 106篇 |
1983年 | 41篇 |
1982年 | 71篇 |
1981年 | 86篇 |
1980年 | 76篇 |
1979年 | 67篇 |
1978年 | 56篇 |
1977年 | 72篇 |
1976年 | 56篇 |
1975年 | 42篇 |
1974年 | 51篇 |
1973年 | 32篇 |
排序方式: 共有6622条查询结果,搜索用时 814 毫秒
991.
Motohiro Suzuki Yuichi Inubushi Makina Yabashi Tetsuya Ishikawa 《Journal of synchrotron radiation》2014,21(3):466-472
A diamond phase retarder was applied to control the polarization states of a hard X‐ray free‐electron laser (XFEL) in the photon energy range 5–20 keV. The horizontal polarization of the XFEL beam generated from the planar undulators of the SPring‐8 Angstrom Compact Free‐Electron Laser (SACLA) was converted into vertical or circular polarization of either helicity by adjusting the angular offset of the diamond crystal from the exact Bragg condition. Using a 1.5 mm‐thick crystal, a high degree of circular polarization, 97%, was obtained for 11.56 keV monochromatic X‐rays, whereas the degree of vertical polarization was 67%, both of which agreed with the estimations including the energy bandwidth of the Si 111 beamline monochromator. 相似文献
992.
993.
Maroni Fabio Bruni Pantaleone Suzuki Naoki Aihara Yuichi Croce Fausto 《Journal of Solid State Electrochemistry》2019,23(6):1697-1703
Journal of Solid State Electrochemistry - All-solid-state batteries represent the next generation of electrochemical energy storage systems. A tin-carbon nanocomposite material is prepared by the... 相似文献
994.
995.
996.
We study global dynamics of a mass conserved reaction–diffusion system. First, we show the global-in-time existence of the solution with compact orbit. Then the dynamical stability of local minima associated with a variational function is proven. 相似文献
997.
Masato Saito Dr. Yusuke Kobayashi Prof. Dr. Yoshiji Takemoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(44):10314-10318
The reactions of thioamides with ortho-nitro-substituted iodonium ylides proceeded under mild conditions to give enaminones or thiazoles, depending on the iodonium ylide used. This protocol allowed the use of protic solvents, including aqueous solutions, and therefore coupling reactions with complex molecules such as peptides or steroids were possible. A mild and efficient method for the synthesis of various iodonium ylides was established. DFT calculations suggested that the halogen bonding between a thioamide and iodonium ylide was important in this chemoselective coupling reaction. The potential use of enaminones conjugated with pharmaceuticals as prodrugs was also demonstrated. 相似文献
998.
999.
Aromaticity Relocation in Perylene Derivatives upon Two‐Electron Oxidation To Form Anthracene and Phenanthrene 下载免费PDF全文
Akinobu Matsumoto Dr. Mitsuharu Suzuki Dr. Hironobu Hayashi Dr. Daiki Kuzuhara Dr. Junpei Yuasa Prof. Dr. Tsuyoshi Kawai Prof. Dr. Naoki Aratani Prof. Dr. Hiroko Yamada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14462-14466
We prepared perylene dications 1 2+ and 2 2+ by using “capped” perylene derivatives, and for the first time, successfully obtained single crystals of a perylene dication 1 2+ that enabled us to perform its structural analysis. We realized that the substituted aryl groups on perylene control the positions of positive charges, thus the remaining electronic system satisfies Clar's sextet rule toward the highest number of localized sextets. Experimental and theoretical evidence proved that Clar's aromatic π‐sextet rule could be applied even for the dicationic perylenes in a very simple way. 相似文献
1000.
Yuto Kurasaki Yasuhito Suzuki Akikazu Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》2020,58(7):923-931
We carried out the thermal curing of the copolymers of N-allylmaleimide (AMI) and 2-ethylhexyl acrylate (2EHA) using 1,3,4,6-tetra(2-mercaproethyl)glycoluril ( G1 ), 1,3,4,6-tetra(3-mercaptopropyl)glycoluril ( G2 ), 1,3,4,6-tetraallylglycoluril ( G3 ), triallylisocyanurate (TAIC), and pentaerythritol tetrakis(3-mercaptobutyrate) (PEMB) as the crosslinkers. Based on the results for the analysis of thiol–ene reactions monitored by IR spectroscopy, it was confirmed that the curing rate significantly depended on the combination of the used crosslinkers. The insoluble fraction after curing was more than 90% for the systems using the glycoluril crosslinkers, while the conversion of the allyl groups was suppressed due to the rigid structure of these crosslinkers. The heat resistance and the mechanical properties of the crosslinked polymers were investigated by thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and mechanical tensile tests. For the products cured using the glycoluril crosslinkers, the glass transition temperature (Tg) and the maximum temperature of thermal decomposition (Tmax) were 54–59 °C and 395–409 °C, respectively, being higher than those for the cured product prepared with PEMB and TAIC as the conventional crosslinkers. The elasticity (75–139 MPa), the maximum strength (3.0–4.1 MPa), and the adhesion strength (6.7–10.7 MPa) for the polymers cured with the glycoluril crosslinkers, determined by the mechanical tensile and single lap-shear adhesion tests, were higher than those for cured materials produced with PEMB. Thus, the thermal and mechanical properties of the maleimide copolymers were efficiently enhanced by crosslinking using the rigid glycoluril compounds. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 923–931 相似文献