全文获取类型
收费全文 | 2117篇 |
免费 | 64篇 |
专业分类
化学 | 1493篇 |
晶体学 | 33篇 |
力学 | 24篇 |
数学 | 74篇 |
物理学 | 557篇 |
出版年
2023年 | 13篇 |
2021年 | 12篇 |
2020年 | 23篇 |
2019年 | 28篇 |
2018年 | 22篇 |
2017年 | 18篇 |
2016年 | 40篇 |
2015年 | 44篇 |
2014年 | 38篇 |
2013年 | 107篇 |
2012年 | 86篇 |
2011年 | 100篇 |
2010年 | 54篇 |
2009年 | 55篇 |
2008年 | 111篇 |
2007年 | 105篇 |
2006年 | 108篇 |
2005年 | 106篇 |
2004年 | 107篇 |
2003年 | 84篇 |
2002年 | 77篇 |
2001年 | 62篇 |
2000年 | 42篇 |
1999年 | 18篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 30篇 |
1994年 | 20篇 |
1993年 | 21篇 |
1992年 | 27篇 |
1991年 | 29篇 |
1990年 | 26篇 |
1989年 | 27篇 |
1988年 | 26篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 47篇 |
1984年 | 36篇 |
1983年 | 30篇 |
1982年 | 27篇 |
1981年 | 34篇 |
1980年 | 24篇 |
1979年 | 41篇 |
1978年 | 33篇 |
1977年 | 17篇 |
1976年 | 31篇 |
1975年 | 20篇 |
1974年 | 15篇 |
1973年 | 13篇 |
1967年 | 13篇 |
排序方式: 共有2181条查询结果,搜索用时 44 毫秒
1.
Ryuto Yasui Dr. Daiki Shimizu Prof. Kenji Matsuda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(27):e202104242
The single-molecular conductance between two π-conjugated wires with and without a radical substituent has been compared. Specifically, methyl- and iminonitroxide-substituted 4-(biphenyl-4-yl)pyridine wires bound onto a porphyrin template were subjected to scanning tunneling microscopy (STM) apparent-height measurement at the interface between highly oriented pyrolytic graphite (HOPG) and octan-1-oic acid. Statistical analysis of the STM images revealed that the radical-substituted wire has 3.2±1.7-fold higher conductance than the methyl-substituted reference. Although density functional theory (DFT) calculation suggests that only 17 % of the SOMO is distributed on the wire moiety, the effect was significant. This study presents the potential of radical substituents to achieve high conductivity in molecular wires. 相似文献
2.
Rational Molecular Design towards Vis/NIR Absorption and Fluorescence by using Pyrrolopyrrole aza‐BODIPY and its Highly Conjugated Structures for Organic Photovoltaics 下载免费PDF全文
Prof. Dr. Soji Shimizu Taku Iino Prof. Dr. Akinori Saeki Prof. Dr. Shu Seki Prof. Dr. Nagao Kobayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2893-2904
Pyrrolopyrrole aza‐BODIPY (PPAB) developed in our recent study from diketopyrrolopyrrole by titanium tetrachloride‐mediated Schiff‐base formation reaction with heteroaromatic amines is a highly potential chromophore due to its intense absorption and fluorescence in the visible region and high fluorescence quantum yield, which is greater than 0.8. To control the absorption and fluorescence of PPAB, particularly in the near‐infrared (NIR) region, further molecular design was performed using DFT calculations. This results in the postulation that the HOMO–LUMO gap of PPAB is perturbed by the heteroaromatic moieties and the aryl‐substituents. Based on this molecular design, a series of new PPAB molecules was synthesized, in which the largest redshifts of the absorption and fluorescence maxima up to 803 and 850 nm, respectively, were achieved for a PPAB consisting of benzothiazole rings and terthienyl substituents. In contrast to the sharp absorption of PPAB, a PPAB dimer, which was prepared by a cross‐coupling reaction of PPAB monomers, exhibited panchromatic absorption across the UV/Vis/NIR regions. With this series of PPAB chromophores in hand, a potential application of PPAB as an optoelectronic material was investigated. After identifying a suitable PPAB molecule for application in organic photovoltaic cells based on evaluation using time‐resolved microwave conductivity measurements, a maximized power conversion efficiency of 1.27 % was achieved. 相似文献
3.
4.
Prof. Dr. Masaki Shimizu Sho Nagano Takumi Kinoshita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5162-5167
Fluorescence–phosphorescence dual-emissive compounds are valuable tools for ratiometric luminescence sensing. Herein, it is reported that 2,5-bis(phenylsulfonyl)- and 2,5-bis[bis(4-methoxyphenyl)phosphinyl]-1,4-disiloxybenzenes exhibit dual emission with emission peaks that were easily identified without performing time-gated measurement. The disiloxybenzenes in powder simultaneously fluoresced and phosphoresced at 358–374 and 457–470 nm, respectively, under vacuum. The intensity ratios of the phosphorescence/fluorescence maxima of the disiloxybenzenes in powder and in a thin film of poly(methyl methacrylate) were sensitive to temperature and molecular oxygen, respectively. The plots of the relative intensity versus temperature or partial pressure of molecular oxygen were well fitted with calibration curves defined by an exponential approximation with excellent correlation coefficients R2 (0.9708–0.9921), demonstrating the high potential of the disiloxybenzenes as precious metal-free probes applicable to ratiometric luminescence sensing. 相似文献
5.
Lars J. Wesenberg Erika Diehl Till J. B. Zähringer Carolin Dörr Dr. Dieter Schollmeyer Dr. Akihiro Shimizu Prof. Dr. Jun-ichi Yoshida Prof. Dr. Ute A. Hellmich Prof. Dr. Siegfried R. Waldvogel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17574-17580
The efficient production of many medicinally or synthetically important starting materials suffers from wasteful or toxic precursors for the synthesis. In particular, the aromatic non-protected primary amine function represents a versatile synthetic precursor, but its synthesis typically requires toxic oxidizing agents and transition metal catalysts. The twofold electrochemical amination of activated benzene derivatives via Zincke intermediates provides an alternative sustainable strategy for the formation of new C−N bonds of high synthetic value. As a proof of concept, we use our approach to generate a benzoxazinone scaffold that gained attention as a starting structure against castrate-resistant prostate cancer. Further improvement of the structure led to significantly increased cancer cell line toxicity. Thus, exploiting environmentally benign electrooxidation, we present a new versatile and powerful method based on direct C−H activation that is applicable for example the production of medicinally relevant compounds. 相似文献
6.
7.
8.
Noriko Shimizu Tomoji Ozeki Hideyasu Shikama Tsuneji Sano Masahiro Sadakane 《Journal of Cluster Science》2014,25(3):755-770
We found that three isomers of mono-Ru substituted Keggin-type germanotungstate with a dmso ligand, [GeW11O39RuII(dmso)]6?, could be formed by a reaction of α-Keggin-type mono-lacunary germanotungstate, [α-GeW11O39]8?, with Ru(dmso)4Cl2. The main isomer is an α-isomer, and the others are β2-isomer and β3-isomer, which were confirmed by 1H NMR, cyclic voltammetry, IR, and single crystal X-ray structure analysis. 相似文献
9.
Inside Cover: Lipid Nanotube Tailored Fabrication of Uniquely Shaped Polydopamine Nanofibers as Photothermal Converters (Chem. Eur. J. 13/2016) 下载免费PDF全文
10.
Yumiko Ohtsuka Prof. Takahiro Seki Prof. Yukikazu Takeoka 《Angewandte Chemie (International ed. in English)》2015,54(51):15368-15373
We report the preparation of thermally tunable hydrogels displaying angle‐independent structural colors. The porous structures were formed with short‐range order using colloidal amorphous array templates and a small amount of carbon black (CB). The resultant porous hydrogels prepared using colloidal amorphous arrays without CB appeared white, whereas the hydrogels with CB revealed bright structural colors. The brightly colored hydrogels rapidly changed hues in a reversible manner, and the hues varied widely depending on the water temperature. Moreover, the structural colors were angle‐independent under diffusive lighting because of the isotropic nanostructure generated from the colloidal amorphous arrays. 相似文献