全文获取类型
收费全文 | 458篇 |
免费 | 27篇 |
国内免费 | 6篇 |
专业分类
化学 | 324篇 |
晶体学 | 5篇 |
力学 | 11篇 |
数学 | 86篇 |
物理学 | 65篇 |
出版年
2024年 | 7篇 |
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 14篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 12篇 |
2016年 | 29篇 |
2015年 | 23篇 |
2014年 | 33篇 |
2013年 | 26篇 |
2012年 | 48篇 |
2011年 | 33篇 |
2010年 | 26篇 |
2009年 | 23篇 |
2008年 | 35篇 |
2007年 | 29篇 |
2006年 | 28篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1995年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有491条查询结果,搜索用时 31 毫秒
141.
Palladium‐Catalyzed Chain‐Growth Polycondensation of AB‐type Monomers: High Catalyst Turnover and Polymerization Rates
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Roman Tkachov Dr. Volodymyr Senkovskyy Dr. Tetyana Beryozkina Dr. Kseniya Boyko Prof. Dr. Vasiliy Bakulev Dr. Albena Lederer Dr. Karin Sahre Prof. Dr. Brigitte Voit Dr. Anton Kiriy 《Angewandte Chemie (International ed. in English)》2014,53(9):2402-2407
Chain‐growth catalyst‐transfer polycondensations of AB‐type monomers is a new and rapidly developing tool for the preparation of well‐defined π‐conjugated (semiconducting) polymers for various optoelectronic applications. Herein, we report the Pd/PtBu3‐catalyzed Negishi chain‐growth polycondensation of AB‐type monomers, which proceeds with unprecedented TONs of above 100 000 and TOFs of up to 280 s?1. In contrast, related AA/BB‐type step‐growth polycondensation proceeds with two orders of magnitude lower TONs and TOFs. A similar trend was observed in Suzuki‐type polycondensation. The key impact of the intramolecular (vs. intermolecular) catalyst‐transfer process on both polymerization kinetics and catalyst lifetime has been revealed. 相似文献
142.
143.
Direct Photocontrol of Peptidomimetics: An Alternative to Oxygen‐Dependent Photodynamic Cancer Therapy
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Oleg Babii Dr. Sergii Afonin Prof. Liudmyla V. Garmanchuk Dr. Viktoria V. Nikulina Tetiana V. Nikolaienko Olha V. Storozhuk Dmytro V. Shelest Dr. Olga I. Dasyukevich Prof. Liudmyla I. Ostapchenko Dr. Volodymyr Iurchenko Dr. Sergey Zozulya Prof. Anne S. Ulrich Prof. Igor V. Komarov 《Angewandte Chemie (International ed. in English)》2016,55(18):5493-5496
Conventional photodynamic treatment strategies are based on the principle of activating molecular oxygen in situ by light, mediated by a photosensitizer, which leads to the generation of reactive oxygen species and thereby causes cell death. A diarylethene‐derived peptidomimetic is presented that is suitable for photodynamic cancer therapy without any involvement of oxygen. This light‐sensitive molecule is not a mediator but is itself the cytotoxic agent. As a derivative of the cyclic amphiphilic peptide gramicidin S, the peptidomimetic exists in two thermally stable photoforms that are interconvertible by light of different wavelengths. The isomer generated by visible light shows much stronger toxicity against tumor cells than the UV‐generated isomer. First in vivo applications are demonstrated on a tumor animal model to illustrate how the peptidomimetic can be administered in the less toxic form and then activated locally in a solid tumor by visible light. 相似文献
144.
Viktoria S. Moskvina Olexander V. Turov Volodymyr P. Khilya Myroslav M. Garazd Ulrich M. Groth 《Monatshefte für Chemie / Chemical Monthly》2008,43(4):1391-1396
New functionalized derivatives of 8,8,10-trimethyl-4-phenyl-7,8-dihydro-2H,6H-pyrano[3,2-g]-chromene-2,6-dione – analogues of the natural compound graveolone – possessing hydrazine, hydroxylamine, and thiosemicarbazide
residues were synthesized and their reactions with acetic anhydride were studied. The structure of the obtained compounds
was confirmed by NMR spectroscopy. 相似文献
145.
Viktoria S. Moskvina Olexander V. Turov Volodymyr P. Khilya Myroslav M. Garazd Ulrich M. Groth 《Monatshefte für Chemie / Chemical Monthly》2008,139(11):1391-1396
New functionalized derivatives of 8,8,10-trimethyl-4-phenyl-7,8-dihydro-2H,6H-pyrano[3,2-g]-chromene-2,6-dione – analogues of the natural compound graveolone – possessing hydrazine, hydroxylamine, and thiosemicarbazide
residues were synthesized and their reactions with acetic anhydride were studied. The structure of the obtained compounds
was confirmed by NMR spectroscopy.
Correspondence: Viktoria Moskvina, Chemistry Department, Kyiv National Taras Shevchenko University, 60, ul. Vladimirskaya,
01033 Kyiv, Ukraine. 相似文献
146.
Volodymyr Smetana Volodymyr Babizhetskyy Arndt Simon Prof. Dr. Dr. h.c. 《无机化学与普通化学杂志》2008,634(4):629-632
Three new metal‐rich phases, Li4Na11Ba14LiN6, Li5Na10Ba14LiN6 and Na14Ba14LiN6 have been prepared and their crystal structure determined. According to single crystal and powder X‐ray diffraction data, all compounds crystallize with cubic unit cells (Li4Na11Ba14LiN6: , a = 17.874(2) Å, Z = 4, V = 5710(1) Å3; Li5Na10Ba14LiN6: , a = 17.799(1) Å, Z = 4, V = 5638.7(6) Å3; Na14Ba14LiN6: , a = 17.7955(5) Å, Z = 4, V = 5635.6(2) Å). The last mentioned compound crystallizes in the Na14Ba14CaN6 type, and both Li4Na11Ba14LiN6 and Li5Na10Ba14LiN6 have related structures. These compounds open a series of metal‐rich Ba nitrides, containing the new Ba14LiN6 cluster. 相似文献
147.
99Tc chemical shifts of TcO4(-), TcH9(2-), TcOF5, TcO2F4(-), TcOCl4(-), Tc2(CO)10, and Tc(CO)3L3(+) (L = CO, MeCN, H2O) are computed using geometries optimized with the gradient-corrected BP86 and hybrid B3P86 density functionals, at the gauge-including atomic orbitals (GIAO), -BPW91 and -B3LYP levels. For this set of compounds, substituent effects on delta(99Tc) are better described with the pure BPW91 functional than with B3LYP, in contrast to most other transition-metal chemical shifts studied so far. A rough, qualitative correlation is found between computed electric-field gradients at the Tc nuclei and the corresponding 99Tc NMR line widths. Thermal and solvation effects on magnetic shielding constants of aqueous TcO4(-), as assessed by averaging these properties over trajectories from Car-Parrinello molecular dynamics simulations, are indicated to be small and comparable to those of MnO4(-). Complexation to aqueous uranyl, UO2(2+), is predicted to affect delta(99Tc) of TcO4(-) only slightly; somewhat larger complexation shifts are obtained for the oxygen nuclei of pertechnetate, suggesting that 17O NMR could be a useful probe for the extent of association between both radionuclides in solution. 相似文献
148.
Volodymyr Pavlyuk Grygoriy Dmytriv Ivan Tarasiuk Hermann Pauly Helmut Ehrenberg 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(2):i15-i17
The new ternary lithium copper aluminide Li8Cu12+xAl6−x (x = 1.16) crystallizes in the P63/mmc space group with six independent atom positions of site symmetries m. (Al/Cu mixture), m2 (Li atoms), 3m. (Al/Cu mixture and Li atoms) and .m. (Cu atoms). The compound is a derivative of the K7Cs6 binary structure type and is related to the binary MgZn2 Laves phase and the LiCuAl2, MgCu1.07Al0.93 and Mg(Cu1−xAlx)2 (x = 0.465) ternary Laves phases. The coordination polyhedra of the atoms in this structure are icosahedra (Cu atoms), slightly distorted icosahedra and bicapped hexagonal antiprisms (Al/Cu statistical mixture), and Frank–Kasper and distorted Frank–Kasper polyhedra (Li atoms). All interatomic distances indicate metallic type bonding. 相似文献
149.
Excited-state intramolecular proton transfer distinguishes microenvironments in single- and double-stranded DNA 总被引:1,自引:0,他引:1
Klymchenko AS Shvadchak VV Yushchenko DA Jain N Mély Y 《The journal of physical chemistry. B》2008,112(38):12050-12055
Herein, the efficient interaction of an environment-sensitive fluorophore that undergoes excited-state intramolecular proton transfer (ESIPT) with DNA has been realized by conjugation of a 3-hydroxychromone (3HC) with polycationic spermine. On binding to a double-stranded DNA (dsDNA), the ratio of the two emission bands of the 3HC conjugates changes up to 16-fold, so that emission of the ESIPT product increases dramatically. This suggests an efficient screening of the 3HC fluorophore from the water molecules in the DNA complex, which is probably realized by its intercalation into dsDNA. In sharp contrast, the 3HC conjugates show only moderate changes in the dual emission on binding to a single-stranded DNA (ssDNA), indicating a much higher fluorophore exposure to water at the binding site. Thus, the 3-hydroxychromone fluorophore being conjugated to spermine discriminates the binding of this polycation to dsDNA from that to ssDNA. Consequently, ESIPT-based dyes are promising for monitoring the interaction of polycationic molecules with DNA and probing the microenvironment of their DNA binding sites. 相似文献
150.
The anomalous piezoelectric effect in GaAs nanowires was detected (the piezoelectric strain coefficient up to d33 ≈ 26 pC/N) that is 12 times larger than the theoretically estimated value. This result is explained by the dominant content of the phase with the wurtzite‐type crystal structure in GaAs nanowires and an increased pressing force by the contact layer on the nanowire. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献