全文获取类型
收费全文 | 831篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
化学 | 698篇 |
晶体学 | 3篇 |
力学 | 9篇 |
综合类 | 1篇 |
数学 | 54篇 |
物理学 | 97篇 |
出版年
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2016年 | 16篇 |
2015年 | 15篇 |
2014年 | 35篇 |
2013年 | 34篇 |
2012年 | 31篇 |
2011年 | 57篇 |
2010年 | 24篇 |
2009年 | 32篇 |
2008年 | 37篇 |
2007年 | 58篇 |
2006年 | 38篇 |
2005年 | 46篇 |
2004年 | 30篇 |
2003年 | 34篇 |
2002年 | 41篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 5篇 |
1991年 | 20篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1986年 | 15篇 |
1985年 | 2篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 3篇 |
1971年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有862条查询结果,搜索用时 31 毫秒
81.
Achiral and chiral cationic palladium catalysts, modified with atropisomeric P?N ligands with different steric and electronic properties, can efficiently produce poly(styrene‐alt‐CO) with essentially complete regioregularity and variable tacticity, depending on the ligand geometry; the electronic effect on catalytic activity depends on the geometry of the ligand. 相似文献
82.
83.
84.
85.
86.
We report on an 888 nm pumped passively mode-locked TEM(00)Nd:YVO(4) oscillator providing 56 W of average power at a repetition rate of 110 MHz with 33 ps pulse duration, further amplified to 111 W in a 52% optical efficiency single-pass amplifier stage, maintaining beam quality at M(2)=1.05. Frequency doubling in a LiB(3)O(5) crystal generated up to 87 W at 532 nm, while a third harmonic power of 35 W was achieved in a nonoptimized tripling configuration, corresponding to 80% and 33% conversion efficiency. 相似文献
87.
Regioselective Ring‐Opening Polymerization of a Polyhydroxycarboxylic Acid for the Synthesis of a Nanoscale Carrier Material with pH‐Dependent Stability and Sustained Drug Release 下载免费PDF全文
Dipl.‐Chem. Alexander Ewe Dr. Anita Jansen de Salazar Dipl.‐Phys. Katharina Lemmnitzer Michael Marsch Prof. Dr. Achim Aigner Prof. Dr. Armin Geyer 《Angewandte Chemie (International ed. in English)》2015,54(21):6364-6369
Synthetic polyesters are usually composed of monohydroxycarboxylic acids to avoid the problem of regioselectivity during ring‐opening polymerization. In contrast, the linear polyester BICpoly contains four secondary OH groups and is nevertheless esterified regioselectively at only one of these positions. Neither the synthesis of the tricyclic monomers nor the ring‐opening polymerization requires protecting groups, making BICpoly an attractive novel and biocompatible polymer. BICpoly nanoparticles can be loaded with low‐molecular weight drugs or coated onto surfaces as thin films. The release of loaded compounds makes BICpoly an attractive depot for drug release, as shown herein by loading BICpoly with dyes or the cytostatic drug doxorubicin. BICpoly is distinguishable from other polymers by its characteristic pH‐dependent degradation. 相似文献
88.
Dr. Thomas Lunkenbein Dr. Frank Girgsdies Anna Wernbacher Dr. Johannes Noack Dr. Gudrun Auffermann Akira Yasuhara Achim Klein‐Hoffmann Prof. Wataru Ueda Dr. Maik Eichelbaum Dr. Annette Trunschke Prof. Robert Schlögl Dr. Marc G. Willinger 《Angewandte Chemie (International ed. in English)》2015,54(23):6828-6831
Complex Mo,V‐based mixed oxides that crystallize in the orthorhombic M1‐type structure are promising candidates for the selective oxidation of small alkanes. The oxygen sublattice of such a complex oxide has been studied by annular bright field scanning transmission electron microscopy. The recorded micrographs directly display the local distortion in the metal oxygen octahedra. From the degree of distortion we are able to draw conclusions on the distribution of oxidation states in the cation columns at different sites. The results are supported by X‐ray diffraction and electron paramagnetic resonance measurements that provide integral details about the crystal structure and spin coupling, respectively. 相似文献
89.
Acceleration of Long‐Range Photoinduced Electron Transfer through DNA by Hydroxyquinolines as Artificial Base Pairs 下载免费PDF全文
Dr. Effi Bätzner Dr. Yu Liang Caroline Schweigert Dr. Andreas‐Neil Unterreiner Prof. Dr. Hans‐Achim Wagenknecht 《Chemphyschem》2015,16(8):1607-1612
The C‐nucleoside based on the hydroxyquinoline ligand (Hq) is complementary to itself and forms stable Hq–Hq pairs in double‐stranded DNA. These artificial Hq–Hq pairs may serve as artificial electron carriers for long‐range photoinduced electron transfer in DNA, as elucidated by a combination of gel electrophoretic analysis of irradiated samples and time‐resolved transient absorption spectroscopy. For this study, the Hq–Hq pair was combined with a DNA‐based donor–acceptor system consisting of 6‐N,N‐dimethylaminopyrene conjugated to 2′‐deoxyuridine as photoinducible electron donor, and methyl viologen attached to the 2′‐position of uridine as electron acceptor. The Hq radical anion was identified in the time‐resolved measurements and strand cleavage products support its role as an intermediate charge carrier. Hence, the Hq–Hq pair significantly enhances the electron hopping capability of DNA compared to natural DNA bases over long distances while keeping the self‐assembly properties as the most attractive feature of DNA as a supramolecular architecture. 相似文献