全文获取类型
收费全文 | 2756篇 |
免费 | 97篇 |
国内免费 | 11篇 |
专业分类
化学 | 2227篇 |
晶体学 | 27篇 |
力学 | 29篇 |
数学 | 196篇 |
物理学 | 385篇 |
出版年
2023年 | 19篇 |
2022年 | 12篇 |
2021年 | 22篇 |
2020年 | 44篇 |
2019年 | 43篇 |
2018年 | 29篇 |
2017年 | 23篇 |
2016年 | 56篇 |
2015年 | 55篇 |
2014年 | 89篇 |
2013年 | 185篇 |
2012年 | 144篇 |
2011年 | 178篇 |
2010年 | 120篇 |
2009年 | 107篇 |
2008年 | 181篇 |
2007年 | 162篇 |
2006年 | 185篇 |
2005年 | 186篇 |
2004年 | 166篇 |
2003年 | 137篇 |
2002年 | 104篇 |
2001年 | 30篇 |
2000年 | 28篇 |
1999年 | 13篇 |
1998年 | 22篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 27篇 |
1993年 | 14篇 |
1992年 | 21篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1986年 | 11篇 |
1985年 | 34篇 |
1984年 | 44篇 |
1983年 | 21篇 |
1982年 | 33篇 |
1981年 | 35篇 |
1980年 | 24篇 |
1979年 | 25篇 |
1978年 | 17篇 |
1977年 | 21篇 |
1976年 | 18篇 |
1975年 | 16篇 |
1974年 | 16篇 |
1973年 | 11篇 |
排序方式: 共有2864条查询结果,搜索用时 15 毫秒
1.
Masaharu Ueno Satoshi D. Ohmura Makoto Wada Norikazu Miyoshi 《Tetrahedron letters》2019,60(7):570-573
We developed an environmentally friendly method for aerobic oxidation of alcohols using a commercially available, relatively benign bismuth salt as a catalyst. We found that the catalytic combination of BiBr3 with nitric acid is key for enhancing the reactivity. The reaction proceeds well under air, making the use of pure oxygen unnecessary. Each of the primary or secondary alcohols tested was oxidized to the corresponding aldehydes or ketones using this protocol. 相似文献
2.
3.
Aoshima Makoto Yata Kazuyoshi 《Annals of the Institute of Statistical Mathematics》2019,71(3):473-503
Annals of the Institute of Statistical Mathematics - We consider classifiers for high-dimensional data under the strongly spiked eigenvalue (SSE) model. We first show that high-dimensional data... 相似文献
4.
Shigeaki Koike Takahiro Kosugi Makoto Naito 《Journal of Mathematical Analysis and Applications》2018,457(1):436-460
The rate of convergence of approximate solutions via penalization for free boundary problems are concerned. A key observation is to obtain global bounds of penalized terms which give necessary estimates on integrations by the nonlinear adjoint method by L.C. Evans. 相似文献
5.
6.
7.
8.
Naofumi Nishida Yuki Hori Akane Yamauchi Hazuki Fujiwara Makoto Sakurai Yuya Fujiwara Shin-ichi Honda Shunjiro Fujii Hiroyuki A. Sakaue Daiji Kato Tomohiro Yamaguchi Koji Ishibashi Toshifumi Terui Kuei-Yi Lee 《X射线光谱测定》2020,49(1):99-103
Interaction of highly charged ions (HCIs) with surfaces produce various specific phenomena as a consequence of the potential energy that HCI possesses. In the present study, we have observed photon emission, structural, magnetic, and electronic modification on various carbon-based materials such as carbon nanotube by the impact of HCIs using an electron beam ion source named Kobe EBIS installed at the Kobe University. In order to study the potential effect, HCIs of Arq+ (q = 6–16) with the intensity of 0.1–1 nA are projected on the surface with a constant kinetic energy (16 keV). For photon emission measurements, we observed spatial and spectral distribution of visible light emission from the surface during irradiation with HCIs. On the other hand, the structural modification of multi-walled carbon nanotubes (MWCNTs) irradiated with HCIs has been analyzed using a transmission electron microscopy and Raman spectroscopy. Irradiation effects on the resistivity of single MWCNT supported on micrometer scale bridge pattern were also measured. We have also measured magnetic structure of highly oriented pyrolytic graphite irradiated with HCIs using electron spin resonance at low temperature. At the present paper, we will review our recent experimental results on the interaction of HCI with various carbon-based materials. 相似文献
9.
Prof. Isao Fujii Dr. Makoto Hashimoto Kaori Konishi Akiko Unezawa Haruka Sakuraba Kenta Suzuki Harue Tsushima Miho Iwasaki Satsuki Yoshida Akane Kudo Rina Fujita Aika Hichiwa Koharu Saito Dr. Takashi Asano Dr. Jun Ishikawa Dr. Daigo Wakana Dr. Yukihiro Goda Ayumi Watanabe Mamoru Watanabe Yui Masumoto Dr. Junichiro Kanazawa Dr. Hajime Sato Prof. Masanobu Uchiyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8542-8548
Shimalactones A and B are neuritogenic polyketides possessing characteristic oxabicyclo[2.2.1]heptane and bicyclo[4.2.0]octadiene ring systems that are produced by the marine fungus Emericella variecolor GF10. We identified a candidate biosynthetic gene cluster and conducted heterologous expression analysis. Expression of ShmA polyketide synthase in Aspergillus oryzae resulted in the production of preshimalactone. Aspergillus oryzae and Saccharomyces cerevisiae transformants expressing ShmA and ShmB produced shimalactones A and B, thus suggesting that the double bicyclo-ring formation reactions proceed non-enzymatically from preshimalactone epoxide. DFT calculations strongly support the idea that oxabicyclo-ring formation and 8π-6π electrocyclization proceed spontaneously after opening of the preshimalactone epoxide ring through protonation. We confirmed the formation of preshimalactone epoxide in vitro, followed by its non-enzymatic conversion to shimalactones in the dark. 相似文献
10.
Ami Saito Dr. Tomohisa Sawada Prof. Dr. Makoto Fujita 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20547-20550
Porous metal complexes enable single-crystal X-ray crystallographic observation of included guests or reaction intermediates through simple soaking with the guests/substrates. Previous studies on this technique have often encountered difficulties in the observation of chiral structures because the host frameworks had no chirality. We synthesized a new metal–peptide porous complex through a folding-and-assembly strategy and utilized the chiral pore for trapping chiral guests. Chiral alcohols and ketones were successfully included within the pore. Crystallographic analyses clearly revealed not only their chemical structures but also chiral transformation events within the pore such as fixed conformations or an unstable hemiacetal formation. 相似文献