全文获取类型
收费全文 | 1384篇 |
免费 | 53篇 |
国内免费 | 9篇 |
专业分类
化学 | 1070篇 |
晶体学 | 18篇 |
力学 | 13篇 |
数学 | 89篇 |
物理学 | 256篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 10篇 |
2020年 | 27篇 |
2019年 | 35篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 39篇 |
2015年 | 38篇 |
2014年 | 32篇 |
2013年 | 76篇 |
2012年 | 58篇 |
2011年 | 80篇 |
2010年 | 48篇 |
2009年 | 58篇 |
2008年 | 101篇 |
2007年 | 70篇 |
2006年 | 92篇 |
2005年 | 76篇 |
2004年 | 70篇 |
2003年 | 69篇 |
2002年 | 58篇 |
2001年 | 30篇 |
2000年 | 23篇 |
1999年 | 18篇 |
1998年 | 17篇 |
1997年 | 7篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有1446条查询结果,搜索用时 10 毫秒
41.
Tomohiro Seki Chi Feng Kentaro Kashiyama Shunichi Sakamoto Yuichi Takasaki Toshiyuki Sasaki Satoshi Takamizawa Hajime Ito 《Angewandte Chemie (International ed. in English)》2020,59(23):8839-8843
Ferroelasticity has been reported for several types of molecular crystals, which show mechanical‐stress‐induced shape change under twinning and/or spontaneous formation of strain. Aiming to create materials that exhibit both ferroelasticity and light‐emission characteristics, we discovered the first examples of ferroelastic luminescent organometallic crystals. Crystals of arylgold(I)(N‐heterocyclic carbene)(NHC) complexes bend upon exposure to anisotropic mechanical stress. X‐ray diffraction analyses and stress‐strain measurements on these ferroelastic crystals confirmed typical ferroelastic behavior, mechanical twinning, and the spontaneous build‐up of strain. A comparison with single‐crystal structures of related gold‐NHC complexes that do not show ferroelasticity shed light on the structural origins of the ferroelastic behavior. 相似文献
42.
Dr. Hikaru Sotome Dr. Hajime Okajima Tatsuhiro Nagasaka Yuka Tachii Prof. Akira Sakamoto Prof. Seiya Kobatake Prof. Masahiro Irie Prof. Hiroshi Miyasaka 《Chemphyschem》2020,21(14):1524-1530
The geometrical evolution of the reactant and formation of the photoproduct in the cycloreversion reaction of a diarylethene derivative were probed using time-resolved absorption spectroscopies in the visible to near-infrared and mid-infrared regions. The time-domain vibrational data in the visible region show that the initially formed Franck-Condon state is geometrically relaxed into the minimum in the excited state potential energy surface, concomitantly with the low-frequency coherent vibrations. Theoretical calculations indicate that the nuclear displacement in this coherent vibration is nearly parallel to that in the geometrical relaxation. Time-resolved mid-infrared spectroscopy directly detected the formation of the open-ring isomer with the same time constant as the decrease of the closed-ring isomer in the excited state minimum. This observation reveals that no detectable intermediate, in which the population is accumulated, is present between the excited closed-ring isomer and the open-ring isomer in the ground state. 相似文献
43.
Yulu Jiang Taro Ozaki Mei Harada Tadachika Miyasaka Hajime Sato Kazunori Miyamoto Junichiro Kanazawa Chengwei Liu Jun‐ichi Maruyama Masaatsu Adachi Atsuo Nakazaki Toshio Nishikawa Masanobu Uchiyama Atsushi Minami Hideaki Oikawa 《Angewandte Chemie (International ed. in English)》2020,59(41):17996-18002
Lolitrems are tremorgenic indole diterpenes that exhibit a unique 5/6 bicyclic system of the indole moiety. Although genetic analysis has indicated that the prenyltransferase LtmE and the cytochrome P450 LtmJ are involved in the construction of this unique structure, the detailed mechanism remains to be elucidated. Herein, we report the reconstitution of the biosynthetic pathway for lolitrems employing a recently established genome‐editing technique for the expression host Aspergillus oryzae. Heterologous expression and bioconversion of the various intermediates revealed that LtmJ catalyzes multistep oxidation to furnish the lolitrem core. We also isolated the key reaction intermediate with an epoxyalcohol moiety. This observation allowed us to establish the mechanism of radical‐induced cyclization, which was firmly supported by density functional theory calculations and a model experiment with a synthetic analogue. 相似文献
44.
Ying An Masahiro Suzuki Toshiki Koyama Kenji Hanabusa Hirofusa Shirai Mei-Yu Huang Ying-Jan Jiang 《先进技术聚合物》1996,7(8):652-656
The palladium cluster protected by silica-supported, crosslinking, partially phosphorylated poly(vinyl alcohol) (P-PVA) was prepared from a crosslinking P-PVA–Pd(II) complex by reduction in alcohol. The P-PVA–Pd complex and the palladium cluster protected by P-PVA were analyzed by electron spectroscopy, X-ray photoelectron spectrometry and transmission electron microscopy. The complex formation between the Pd(II) ion and phosphoric acid groups in P-PVA was important in the formation of a fine palladium cluster. Palladium clusters protected by silica-supported crosslinking P-PVA were used as catalysts for the hydrogenation of nitrobenzene or acrylic acid at 30°C under atmospheric pressure. The palladium cluster protected by crosslinking P-PVA supported on silica was the most active catalyst, was stable and had no by-products, compared with the palladium cluster protected by silica-supported noncrosslinking P-PVA or PVA. 相似文献
45.
Naoya Onishi Ryoichi Kanega Hajime Kawanami Yuichiro Himeda 《Molecules (Basel, Switzerland)》2022,27(2)
Recently, there has been a strong demand for technologies that use hydrogen as an energy carrier, instead of fossil fuels. Hence, new and effective hydrogen storage technologies are attracting increasing attention. Formic acid (FA) is considered an effective liquid chemical for hydrogen storage because it is easier to handle than solid or gaseous materials. This review presents recent advances in research into the development of homogeneous catalysts, primarily focusing on hydrogen generation by FA dehydrogenation. Notably, this review will aid in the development of useful catalysts, thereby accelerating the transition to a hydrogen-based society. 相似文献
46.
Hirofusa Shirai Kenji Hanabusa Toshiki Koyama Hisanaga Tsuiki Etsuko Masuda 《Macromolecular Symposia》1992,59(1):155-162
The oxidation of HO-CH2-CH2-SH (RSH) by molecular oxygen and Fe(III)- as well as Co(II)-multicarboxyphthalocyanine and the mechanism in homogeneous aqueous system were investigated. As application to enzyme-like heterogeneous catalysts, Fe(III)-as well as Co(II)-octacarboxyphthalocyanine were supported on amorphous enriched rayon staple fiber and their enzyme-like activities were estimated. These fibers were applicated to new odor-removers acting as artificial enzyme systems. 相似文献
47.
48.
Prof. Makoto Tadokoro Masaki Itoh Ryota Nishimura Kensuke Sekiguchi Dr. Norihisa Hoshino Dr. Hajime Kamebuchi Prof. Jun Miyazaki Dr. Fumiya Kobayashi Prof. Motohiro Mizuno Prof. Tomoyuki Akutagawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(47):e202201397
A new H-bonded crystal [RuIII(Him)3(Im)3] with three imidazole (Him) and three imidazolate (Im−) groups was prepared to obtain a higher-temperature proton conductor than a Nafion membrane with water driving. The crystal is constructed by complementary N−H⋅⋅⋅N H-bonds between the RuIII complexes and has a rare Icy-c* cubic network topology with a twofold interpenetration without crystal anisotropy. The crystals show a proton conductivity of 3.08×10−5 S cm−1 at 450 K and a faster conductivity than those formed by only HIms. The high proton conductivity is attributed to not only molecular rotations and hopping motions of HIm frameworks that are activated at ∼113 K, but also isotropic whole-molecule rotation of [RuIII(Him)3(Im)3] at temperatures greater than 420 K. The latter rotation was confirmed by solid-state 2H NMR spectroscopy; probable proton conduction routes were predicted and theoretically considered. 相似文献
49.
Application of digital image analysis (DIA) to polymer blends morphology is discussed with examples. Various operations in DIA including two-dimensional Fourier transformation (2DFT), intensity distribution, recursive region extraction, etc. are applied to morphology of polymer blends due to spinodal decomposition (SD), nucleation 6 growth (NG), and eutectic solidification (ES). Merits and drawbacks of DIA to study polymer blends morphology are discussed and the possibility of future development is presented. 相似文献
50.