全文获取类型
收费全文 | 4948篇 |
免费 | 88篇 |
国内免费 | 9篇 |
专业分类
化学 | 3576篇 |
晶体学 | 10篇 |
力学 | 49篇 |
数学 | 803篇 |
物理学 | 607篇 |
出版年
2021年 | 30篇 |
2020年 | 32篇 |
2019年 | 31篇 |
2016年 | 90篇 |
2015年 | 66篇 |
2014年 | 88篇 |
2013年 | 182篇 |
2012年 | 165篇 |
2011年 | 172篇 |
2010年 | 109篇 |
2009年 | 102篇 |
2008年 | 142篇 |
2007年 | 161篇 |
2006年 | 166篇 |
2005年 | 167篇 |
2004年 | 159篇 |
2003年 | 117篇 |
2002年 | 121篇 |
2001年 | 84篇 |
2000年 | 56篇 |
1999年 | 70篇 |
1998年 | 82篇 |
1997年 | 88篇 |
1996年 | 91篇 |
1995年 | 74篇 |
1994年 | 86篇 |
1993年 | 84篇 |
1992年 | 91篇 |
1991年 | 65篇 |
1990年 | 81篇 |
1989年 | 84篇 |
1988年 | 80篇 |
1987年 | 89篇 |
1986年 | 114篇 |
1985年 | 124篇 |
1984年 | 91篇 |
1983年 | 80篇 |
1982年 | 78篇 |
1981年 | 75篇 |
1980年 | 98篇 |
1979年 | 56篇 |
1978年 | 86篇 |
1977年 | 76篇 |
1976年 | 72篇 |
1975年 | 44篇 |
1974年 | 63篇 |
1973年 | 57篇 |
1972年 | 53篇 |
1971年 | 42篇 |
1970年 | 49篇 |
排序方式: 共有5045条查询结果,搜索用时 0 毫秒
71.
Influence of higher harmonics of the undulator in X‐ray polarimetry and crystal monochromator design 下载免费PDF全文
Berit Marx‐Glowna Kai S. Schulze Ingo Uschmann Tino Kämpfer Günter Weber Christoph Hahn Hans‐Christian Wille Kai Schlage Ralf Röhlsberger Eckhart Förster Thomas Stöhlker Gerhard G. Paulus 《Journal of synchrotron radiation》2015,22(5):1151-1154
The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel‐cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs. 相似文献
72.
Excellent passivation of thin silicon wafers by HF‐free hydrogen plasma etching using an industrial ICPECVD tool 下载免费PDF全文
Muzhi Tang Jia Ge Johnson Wong Zhi Peng Ling Torsten Dippell Zhenhao Zhang Marco Huber Manfred Doerr Oliver Hohn Peter Wohlfart Armin Gerhard Aberle Thomas Mueller 《固体物理学:研究快报》2015,9(1):47-52
In this work, hydrogen plasma etching of surface oxides was successfully accomplished on thin (~100 µm) planar n‐type Czochralski silicon wafers prior to intrinsic hydrogenated amorphous silicon [a‐Si:H(i)] deposition for heterojunction solar cells, using an industrial inductively coupled plasma‐enhanced chemical vapour deposition (ICPECVD) platform. The plasma etching process is intended as a dry alternative to the conventional wet‐chemical hydrofluoric acid (HF) dip for solar cell processing. After symmetrical deposition of an a‐Si:H(i) passivation layer, high effective carrier lifetimes of up to 3.7 ms are obtained, which are equivalent to effective surface recombination velocities of 1.3 cm s–1 and an implied open‐circuit voltage (Voc) of 741 mV. The passivation quality is excellent and comparable to other high quality a‐Si:H(i) passivation. High‐resolution transmission electron microscopy shows evidence of plasma‐silicon interactions and a sub‐nanometre interfacial layer. Using electron energy‐loss spectroscopy, this layer is further investigated and confirmed to be hydrogenated suboxide layers. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
73.
74.
75.
76.
77.
78.
79.
Oskar Nuyken Gerhard Maier Michael Leitner Dazhong Yang Martin Wolf 《Macromolecular Symposia》1995,98(1):269-283
Cationic polymerisation of 1, 4-diisopropenyl benzene, 1, 4-(2-chloro-isopropyl)benzene and related compounds yields soluble polymers with repeating units of indan. High performance polymers with indan units are available via nucleophilic substitution of halogenated aromatic monomers containing a central indan element, which are synthesized from 1, 1, 3-trimethyl-3-phenylindan via Friedel-Crafts-reaction with corresponding halogenated acyl- and sulfonyl chlorides. 相似文献
80.
Gerhard Wegner 《Macromolecular Symposia》1995,98(1):541-541
Processing and performance of fiber reinforced polymers suffer from problems related to the heterogeneous nature of the composites. The strong impact of the nature of the interface between fibers and matrix adds to the complication of the field. Consequently many attempts have been made to reduce the cross-section of the reinforcing fibers to molecular dimensions and to increase the compatibility between the rod-like molecules or bundles of molecules and the isotropic matrix of ordinary flexible polymers. All such attempts have failed, mainly for reasons of thermodynamics which predict immiscibility of rods and coils on the molecular level. A possibility to create structures in which molecular rods are embedded in a continuous matrix of flexible chain segments exists nevertheless.1 Rod-like backbone structures decorated with a skin of flexible side chains of moderate length in terms of the number of carbon atoms (typically C6 - C18-side chains) have been synthesized and tested for the spontaneous formation of molecular composites. Some of the materials built along this principle can be processed by solution casting or even melt extrusion. The academically more interesting materials can be built up layerwise by a modified Langmuir-Blodgett technique. The latter process gives rise to monodomain textures which allow for straight-forward testing of the mechanical properties by optical means (Brillouin-spectroscopy) and by piezoquartz-techniques. Hairy-rod macromolecules can also be synthesized which contain crosslinkable side chains. Thus, after formation of layered, oriented structures, these can be crosslinked photochemically or by curing. The result is a network, which is unidirectionally reinforced by the rod-like macromolecules. These novel types of networks can serve as membranes by which size exclusion is achieved via control of the distance between adjacent backbone molecules in the matrix. Recent synthetic advances in the field have concentrated on hairy-rod macromolecules based on cellulose alkyl ethers and on derivatives of poly-(p-phenylene). The latter materials serve as examples of systems which can be processed by casting and extrusion processes. Due to their excellent thermal stability relevant data on the rheological and mechanical-dynamical data have become available. These data serve to document the unique behavior of the hairy-rod macromolecules as bulk materials. 相似文献