全文获取类型
收费全文 | 2709篇 |
免费 | 89篇 |
国内免费 | 9篇 |
专业分类
化学 | 1968篇 |
晶体学 | 7篇 |
力学 | 28篇 |
数学 | 414篇 |
物理学 | 390篇 |
出版年
2021年 | 21篇 |
2020年 | 41篇 |
2019年 | 44篇 |
2018年 | 21篇 |
2016年 | 62篇 |
2015年 | 64篇 |
2014年 | 75篇 |
2013年 | 93篇 |
2012年 | 126篇 |
2011年 | 139篇 |
2010年 | 91篇 |
2009年 | 61篇 |
2008年 | 103篇 |
2007年 | 129篇 |
2006年 | 141篇 |
2005年 | 129篇 |
2004年 | 85篇 |
2003年 | 79篇 |
2002年 | 89篇 |
2001年 | 56篇 |
2000年 | 40篇 |
1999年 | 41篇 |
1998年 | 38篇 |
1997年 | 28篇 |
1996年 | 26篇 |
1995年 | 35篇 |
1994年 | 38篇 |
1993年 | 34篇 |
1992年 | 50篇 |
1991年 | 30篇 |
1990年 | 29篇 |
1989年 | 31篇 |
1988年 | 40篇 |
1987年 | 45篇 |
1986年 | 32篇 |
1985年 | 43篇 |
1984年 | 31篇 |
1983年 | 23篇 |
1982年 | 22篇 |
1981年 | 29篇 |
1980年 | 33篇 |
1979年 | 22篇 |
1978年 | 31篇 |
1977年 | 25篇 |
1976年 | 29篇 |
1975年 | 32篇 |
1974年 | 34篇 |
1973年 | 33篇 |
1971年 | 21篇 |
1970年 | 17篇 |
排序方式: 共有2807条查询结果,搜索用时 15 毫秒
91.
92.
Elvira Welzig Harald Pichler Rudolf Krska Dietmar Knopp Reinhard Niessner 《International journal of environmental analytical chemistry》2013,93(3-4):279-288
Abstract The development of an indirect competitive enzyme immunoassay for the sulfonylurea herbicide metsulfuron-methyl (MSM) is described. In contrast to traditional antibody generation in mammals, this extremely sensitive method is based on chicken egg yolk antibodies (IgY). They were raised in laying hens using an MSM-derivative-BSA hapten as immunogen. With a 1:10000 dilution of the antibody solution and a coating antigen (MSM-derivative-KLH) concentration of 10 μg L?1 the IC50 value achieved for the target analyte was 0.4 μg L?1. The least detectable dose was established at 13 ng L?1. Cross-reactivity was tested with 5 structurally related compounds, where only sulfometuron showed a significant binding. The ELISA was tested with spiked tap and surface water samples. This paper, for the first time, demonstrates the production of high-affinity IgY antibodies for a herbicide compound. 相似文献
93.
Abstract The synthesis of a new disc-like mesogenic compound permitted, for the first time, ferroelectric electrooptical switching in a tilted columnar liquid crystal. The spontaneous molecular dipole moment is induced by the bend between the dibenzopyrene core and part of the eight O-hexyllactic acid chains attached to it. Two similar new compounds displayed a weak electrooptical effect in the columnar phase. 相似文献
94.
Bernd Tieke Volker Enkelmann Harald Kapp Günter Lieser Gerhard Wegner 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):1045-1058
Abstract The topochemical polymerization of diacetylenes and.the dimerization of cinnamic acid derivatives have been studied in Langmuir-Blodgett-multilayers. The resulting polymer films are of controlled thickness and morphology and exhibit excellent stability. Structure, morphology and phase changes occuring in monomer and polymer films have been investigated using spectroscopic methods, electron and x-ray diffraction. Possible applications of the polymer films are discussed. 相似文献
95.
96.
Dr. Peter Wick Dr. Anna E. Louw‐Gaume Dr. Melanie Kucki Prof. Harald F. Krug Prof. Kostas Kostarelos Prof. Bengt Fadeel Prof. Kenneth A. Dawson Dr. Anna Salvati Prof. Ester Vázquez Dr. Laura Ballerini Dr. Mauro Tretiach Dr. Fabio Benfenati Dr. Emmanuel Flahaut Dr. Laury Gauthier Prof. Maurizio Prato Dr. Alberto Bianco 《Angewandte Chemie (International ed. in English)》2014,53(30):7714-7718
97.
Özlem Usluer Christian Kästner Mamatimin Abbas Christoph Ulbricht Vera Cimrova Andreas Wild Eckhard Birckner Nalan Tekin Niyazi Serdar Sariciftci Harald Hoppe Silke Rathgeber Daniel A. M. Egbe 《Journal of polymer science. Part A, Polymer chemistry》2012,50(16):3425-3436
This article reports on the synthesis, characterization, and properties of various anthracene‐containing poly (p‐phenylene‐ethynylene)‐alt‐poly(p‐phenylene‐vinylene) (PPE‐PPV) polymers (AnE‐PVs) bearing statistical distributions of various side chains. Primarily, the ratio of linear octyloxy and branched 2‐ethylhexyloxy side chains at the poly(p‐phenylene vinylene) (PPV) parts was varied, leading to the polymers stat, stat1, and stat2. Furthermore, polymers also containing asymmetric substituted PPV and poly(p‐phenylene ethynylene) units (bearing methoxy and 2‐ethylhexyloxy side chains) were prepared yielding stat3, stat4, and stat5. These materials exhibit a broad variation in their photovoltaic properties. It is once more shown that side chains and their distribution can crucially affect the photovoltaic device performance. The introduction of units with asymmetric substitution into these systems seems to be harmful for their utilization in photovoltaic applications. Organic field‐effect transistors were fabricated to investigate hole mobilities in these new materials. Large variance was observed, falling in the range of almost two orders of magnitude, indicating rather different π–π stacking behavior of the polymer backbones owing to side‐chain modifications. Moreover, a selection of the new polymeric systems was investigated regarding their potential for light‐emitting diode (LED) applications. Polymer LEDs using the polymers AnE‐PVstat, ‐stat3, ‐stat4, and ‐stat5, as the active layer showed turn‐on voltage of ~2 V and exhibited red light emission. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
98.
99.
Dr. Marcel Sickert Dr. Harald Weinstabl Brendan Peters Xiao Hou Prof. Dr. Mark Lautens 《Angewandte Chemie (International ed. in English)》2014,53(20):5147-5151
A palladium‐catalyzed intermolecular cross‐coupling of two aryl iodides is reported, giving polycyclic ring systems with a high level of convergence and efficiency. 相似文献
100.