全文获取类型
收费全文 | 1804篇 |
免费 | 59篇 |
国内免费 | 6篇 |
专业分类
化学 | 1328篇 |
晶体学 | 24篇 |
力学 | 14篇 |
数学 | 128篇 |
物理学 | 375篇 |
出版年
2021年 | 13篇 |
2020年 | 23篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 11篇 |
2016年 | 40篇 |
2015年 | 44篇 |
2014年 | 44篇 |
2013年 | 65篇 |
2012年 | 87篇 |
2011年 | 98篇 |
2010年 | 64篇 |
2009年 | 49篇 |
2008年 | 89篇 |
2007年 | 107篇 |
2006年 | 87篇 |
2005年 | 91篇 |
2004年 | 103篇 |
2003年 | 86篇 |
2002年 | 85篇 |
2001年 | 43篇 |
2000年 | 37篇 |
1999年 | 15篇 |
1998年 | 19篇 |
1997年 | 11篇 |
1996年 | 24篇 |
1995年 | 22篇 |
1994年 | 24篇 |
1993年 | 17篇 |
1992年 | 19篇 |
1991年 | 26篇 |
1990年 | 27篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 25篇 |
1985年 | 26篇 |
1984年 | 26篇 |
1983年 | 18篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 14篇 |
1978年 | 16篇 |
1977年 | 24篇 |
1976年 | 10篇 |
1975年 | 16篇 |
1974年 | 12篇 |
1973年 | 15篇 |
1972年 | 6篇 |
排序方式: 共有1869条查询结果,搜索用时 15 毫秒
1.
2.
3.
Furuta Etsuko Akiyama Kazuhiko Inoue Hiroyoshi Kataoka Yasuhide Sensui Masaaki 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):109-122
Journal of Radioanalytical and Nuclear Chemistry - A new dipping method was studied for the measurement of radioactive solution using plastic scintillator sheets and pellets (PSs) and a liquid... 相似文献
4.
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
5.
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
6.
7.
High Catalytic Activity of Nitrogen and Sulfur Co‐Doped Nanoporous Graphene in the Hydrogen Evolution Reaction 下载免费PDF全文
Dr. Yoshikazu Ito Weitao Cong Dr. Takeshi Fujita Prof. Zheng Tang Prof. Mingwei Chen 《Angewandte Chemie (International ed. in English)》2015,54(7):2131-2136
Chemical doping has been demonstrated to be an effective way to realize new functions of graphene as metal‐free catalyst in energy‐related electrochemical reactions. Although efficient catalysis for the oxygen reduction reaction (ORR) has been achieved with doped graphene, its performance in the hydrogen evolution reaction (HER) is rather poor. In this study we report that nitrogen and sulfur co‐doping leads to high catalytic activity of nanoporous graphene in HER at low operating potential, comparable to the best Pt‐free HER catalyst, 2D MoS2. The interplay between the chemical dopants and geometric lattice defects of the nanoporous graphene plays the fundamental role in the superior HER catalysis. 相似文献
8.
Carbazole Dendrimers as Solution‐Processable Thermally Activated Delayed‐Fluorescence Materials 下载免费PDF全文
Assist. Prof. Ken Albrecht Assist. Prof. Kenichi Matsuoka Assoc. Prof. Katsuhiko Fujita Prof. Kimihisa Yamamoto 《Angewandte Chemie (International ed. in English)》2015,54(19):5677-5682
Recently, thermally activated delayed fluorescence (TADF) materials have received increasing attention as effective emitters for organic light‐emitting diodes (OLEDs). However, most of them are usually employed as dopants in a host material. In this report, carbazole dendrimers with a triphenyl‐s‐triazine core are reported, which are the first solution‐processable, non‐doped, high‐molecular‐weight TADF materials. The dendrimers were obtained by a new and facile synthetic route using the tert‐butyldimethylsilyl moiety as a protecting group. All dendrimers showed TADF in toluene. Measurements of the temperature‐dependent luminescence lifetime revealed that spin‐coated neat films also showed TADF with moderate quantum yields. OLED devices incorporating these dendrimers as spin‐coated emitting layers gave external quantum efficiencies of up to a 3.4 %, which suggests that this device is harvesting triplet excitons. This result indicates that carbazole dendrimers with attached acceptors are potential TADF materials owing to their polarized electronic structure (with HOMO–LUMO separation). 相似文献
9.
Hydrogen Production from a Methanol–Water Solution Catalyzed by an Anionic Iridium Complex Bearing a Functional Bipyridonate Ligand under Weakly Basic Conditions 下载免费PDF全文
Prof. Dr. Ken‐ichi Fujita Dr. Ryoko Kawahara Takuya Aikawa Prof. Dr. Ryohei Yamaguchi 《Angewandte Chemie (International ed. in English)》2015,54(31):9057-9060
An efficient catalytic system for the production of hydrogen from a methanol–water solution has been developed using a new anionic iridium complex bearing a functional bipyridonate ligand as a catalyst. This system can be operated under mild conditions [weakly basic solution (0.046 mol L?1 NaOH) below 100 °C] without the use of an additional organic solvent. Long‐term continuous hydrogen production from a methanol–water solution catalyzed by the anionic iridium complex was also achieved. 相似文献
10.
Dr. Yasuhide Akizuki Dr. Ikuya Yamada Dr. Koji Fujita Kazuya Taga Dr. Takateru Kawakami Dr. Masaichiro Mizumaki Prof. Katsuhisa Tanaka 《Angewandte Chemie (International ed. in English)》2015,54(37):10870-10874
Of particular interest is a peculiar motion of guest atoms or ions confined to nanospace in cage compounds, called rattling. While rattling provides unexplored physical properties through the guest–host interactions, it has only been observed in a very limited class of materials. Herein, we introduce an A‐site‐ordered quadruple perovskite, CuCu3V4O12, as a new family of cage compounds. This novel AA′3B4O12‐type perovskite has been obtained by a high‐pressure synthesis technique and structurally characterized to have cubic Im$\bar 3$ symmetry with an ionic model of Cu2+Cu2+3V4+4O12. The thermal displacement parameter of the A‐site Cu2+ ion is as large as Uiso≈0.045 Å2 at 300 K, indicating its large‐amplitude thermal oscillations in the oversized icosahedral cages. Remarkably, the presence of localized phonon modes associated with rattling of the A‐site Cu2+ ion manifests itself in the low‐temperature specific heat data. This work sheds new light on the structure–property relations in perovskites. 相似文献