全文获取类型
收费全文 | 1611715篇 |
免费 | 32385篇 |
国内免费 | 8487篇 |
专业分类
化学 | 719003篇 |
晶体学 | 20731篇 |
力学 | 76351篇 |
综合类 | 108篇 |
数学 | 246929篇 |
物理学 | 389756篇 |
无线电 | 199709篇 |
出版年
2021年 | 14877篇 |
2020年 | 17482篇 |
2019年 | 17631篇 |
2018年 | 16485篇 |
2017年 | 14653篇 |
2016年 | 31077篇 |
2015年 | 22191篇 |
2014年 | 32974篇 |
2013年 | 78930篇 |
2012年 | 44504篇 |
2011年 | 45156篇 |
2010年 | 42973篇 |
2009年 | 47021篇 |
2008年 | 47126篇 |
2007年 | 45341篇 |
2006年 | 48726篇 |
2005年 | 42643篇 |
2004年 | 42177篇 |
2003年 | 38966篇 |
2002年 | 39206篇 |
2001年 | 39152篇 |
2000年 | 33970篇 |
1999年 | 30094篇 |
1998年 | 27873篇 |
1997年 | 27608篇 |
1996年 | 27119篇 |
1995年 | 24841篇 |
1994年 | 24336篇 |
1993年 | 23765篇 |
1992年 | 23962篇 |
1991年 | 24084篇 |
1990年 | 22908篇 |
1989年 | 22440篇 |
1988年 | 21700篇 |
1987年 | 20369篇 |
1986年 | 19219篇 |
1985年 | 25680篇 |
1984年 | 26674篇 |
1983年 | 22486篇 |
1982年 | 23804篇 |
1981年 | 23000篇 |
1980年 | 22255篇 |
1979年 | 22359篇 |
1978年 | 23462篇 |
1977年 | 23066篇 |
1976年 | 22694篇 |
1975年 | 21442篇 |
1974年 | 21043篇 |
1973年 | 21550篇 |
1972年 | 15723篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
811.
812.
813.
814.
815.
Facile non‐lithographic route to highly aligned silica nanopatterns using unidirectionally aligned polystyrene‐block‐polydimethylsiloxane films 下载免费PDF全文
Zhe Qiang Maurice L. Wadley Bryan D. Vogt Kevin A. Cavicchi 《Journal of Polymer Science.Polymer Physics》2015,53(15):1058-1064
Thin films (monolayer and bilayer) of cylinder forming polystyrene‐block‐polydimethylsiloxane (PS‐b‐PDMS) were shear aligned by the swelling and deswelling of a crosslinked PDMS pad that was physically adhered to the film during solvent vapor annealing. The nanostructures formed by self‐assembly were exposed to ultraviolet‐ozone to partially oxidize the PDMS, followed by calcination in air at 500 °C. In this process, the PS segments were fully decomposed, while the PDMS yielded silica nanostructures. The highly aligned PDMS cylinders were thus deposited as silica nanolines on the silicon substrate. Using a bilayer film, the center‐to‐center distance of these features were effectively halved from 38 to 19 nm. Similarly, by sequential shear‐alignment of two distinct layers, a rhombic array of silica nanolines was fabricated. This methodology provides a facile route to fabricating complex topographically patterned nanostructures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1058–1064 相似文献
816.
817.
Locke Davenport Huyer Serena Mandla Yufeng Wang Scott B. Campbell Bess Yee Christian Euler Benjamin F. Lai A. Dawn Bannerman Dawn S. Y. Lin Miles Montgomery Kayla Nemr Timothy Bender Slava Epelman Radhakrishnan Mahadevan Milica Radisic 《Advanced functional materials》2021,31(6):2003341
Itaconate (ITA) is an emerging powerhouse of innate immunity with therapeutic potential that is limited in its ability to be administered in a soluble form. A library of polyester materials that incorporate ITA into polymer backbones resulting in materials with inherent immunoregulatory behavior is developed. Harnessing hydrolytic degradation release from polyester backbones, ITA polymers result in the mechanism specific immunoregulatory properties on macrophage polarization in vitro. In a functional assay, the polymer-released ITA inhibits bacterial growth on acetate. Translation to an in vivo model of biomaterial associated inflammation, intraperitoneal injection of ITA polymers demonstrate a rapid resolution of inflammation in comparison to a control polymer silicone, demonstrating the value of sustained biomimetic presentation of ITA. 相似文献
818.
819.
Hideaki Murasugi Dr. Shohei Kumagai Dr. Hiroaki Iguchi Prof. Dr. Masahiro Yamashita Dr. Shinya Takaishi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(42):9885-9891
Crystal structures of a series of organic–inorganic hybrid gold iodide perovskites, formulated as A2[AuII2][AuIIII4] [A=methylammonium (MA) ( 1 ) and formamidinium (FA) ( 2 )], A′2[I3]1−x[AuII2]x[AuIIII4] [A′=imidazolium (IMD) ( 3 ), guanidinium (GUA) ( 4 ), dimethylammonium (DMA) ( 5 ), pyridinium (PY) ( 6 ), and piperizinium (PIP) ( 7 )], systematically changed depending on the cation size. In addition, triiodide (I3−) ions were partly incorporated into the AuI2− sites of 3 – 7 , whereas they were not incorporated into those of 1 and 2 . Such a difference comes from the size of the organic cation. Optical absorption spectra showed characteristic intervalence charge-transfer bands from AuI to AuIII species, and the optical band gap increased as the size of the cation became larger. 相似文献
820.
Minoru Koyama Dr. Takafumi Kawakami Dr. Takashi Okazoe Prof. Dr. Kyoko Nozaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(46):10913-10917
Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3CH2, and n-C6F13CH2CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6F13CH2CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4, with DBU in acetonitrile afforded deuterated MMA (MMA-d8) in 70 % yield. 相似文献