全文获取类型
收费全文 | 1150篇 |
免费 | 27篇 |
国内免费 | 3篇 |
专业分类
化学 | 913篇 |
晶体学 | 16篇 |
力学 | 24篇 |
数学 | 60篇 |
物理学 | 167篇 |
出版年
2023年 | 6篇 |
2021年 | 5篇 |
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 15篇 |
2015年 | 21篇 |
2014年 | 16篇 |
2013年 | 47篇 |
2012年 | 45篇 |
2011年 | 48篇 |
2010年 | 29篇 |
2009年 | 34篇 |
2008年 | 55篇 |
2007年 | 73篇 |
2006年 | 71篇 |
2005年 | 66篇 |
2004年 | 66篇 |
2003年 | 60篇 |
2002年 | 55篇 |
2001年 | 19篇 |
2000年 | 25篇 |
1999年 | 15篇 |
1998年 | 24篇 |
1997年 | 19篇 |
1996年 | 20篇 |
1995年 | 18篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 27篇 |
1984年 | 21篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 15篇 |
1977年 | 17篇 |
1976年 | 14篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1972年 | 4篇 |
排序方式: 共有1180条查询结果,搜索用时 15 毫秒
81.
Kun'ichi Miyazawa Takuro Nagai Koji Kimoto Masaru Yoshitake Yumi Tanaka 《Surface and interface analysis : SIA》2021,53(1):84-89
We analyzed the surface atomic structure of highly oriented pyrolytic graphite (HOPG) substrate exfoliated with adhesive tape, using high‐resolution transmission electron microscopy and scanning transmission electron microscopy‐electron energy‐loss spectroscopy (STEM‐EELS). The surface step height of the exfoliated HOPG substrate was determined using high‐angle annular dark‐field‐scanning transmission electron microscopy (HAADF‐STEM) images and the depth profiles of the EELS spectra of a cross‐sectioned thin foil specimen prepared via focused ion beam milling. The exfoliated surface of the HOPG substrate presented disordered and curved graphene layers. The STEM‐EELS measurements indicated that upon exfoliation, the surface of the HOPG substrate reacted with atmospheric water and oxygen molecules. 相似文献
82.
Direct Asymmetric Mannich‐Type Reaction of α‐Isocyanoacetates with Ketimines using Cinchona Alkaloid/Copper(II) Catalysts
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)
Masashi Hayashi Masaru Iwanaga Noriyuki Shiomi Dr. Daisuke Nakane Prof. Dr. Hideki Masuda Prof. Dr. Shuichi Nakamura 《Angewandte Chemie (International ed. in English)》2014,53(32):8411-8415
The enantioselective direct Mannich‐type reaction of ketimines with α‐isocyanoacetates has been developed. Excellent yields and enantioselectivity were observed for the reaction of various ketimines and α‐isocyanoacetates using cinchona alkaloid/Cu(OTf)2 and a base. Both enantiomers of the products could be obtained by using pseudoenantiomeric chiral catalysts. This process offers an efficient route for the synthesis of α,β‐diamino acids. 相似文献
83.
Jie Zhu Dr. Ryota Osuga Prof. Ryo Ishikawa Prof. Naoya Shibata Prof. Yuichi Ikuhara Prof. Junko N. Kondo Prof. Masaru Ogura Prof. Jihong Yu Prof. Toru Wakihara Prof. Zhendong Liu Prof. Tatsuya Okubo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19837-19842
Encapsulating metal nanoclusters into zeolites combines the superior catalytic activity of the nanoclusters with high stability and unique shape selectivity of the crystalline microporous materials. The preparation of such bifunctional catalysts, however, is often restricted by the mismatching in time scale between the fast formation of nanoclusters and the slow crystallization of zeolites. We herein demonstrate a novel strategy to overcome the mismatching issue, in which the crystallization of zeolites is expedited so as to synchronize it with the rapid formation of nanoclusters. The concept was demonstrated by confining Pt and Sn nanoclusters into a ZSM-5 (MFI) zeolite in the course of its crystallization, leading to an ultrafast, in situ encapsulation within just 5 min. The Pt/Sn-ZSM-5 exhibited exceptional activity and selectivity with stability in the dehydrogenation of propane to propene. This method of ultrafast encapsulation opens up a new avenue for designing and synthesizing composite zeolitic materials with structural and compositional complexity. 相似文献
84.
85.
Front Cover: Construction of a Triangle‐Shaped Trimer and a Tetrahedron Using an α‐Helix‐Inserted Circular Permutant of Cytochrome c555 (Chem. Asian J. 10/2018)
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
86.
This paper shows a computational method for optimizing the location of a store on a network in a competitive environment, assuming that consumers probabilistically choose stores following the Huff model (1963) and that the store can be located on a continuum of a network. This method gives the exact optimal solution with the computational order of n
N
2 logn
N
where n
N
is the number of nodes of the network. 相似文献
87.
Umakoshi K Yamasaki T Fukuoka A Kawano H Ichikawa M Onishi M 《Inorganic chemistry》2002,41(16):4093-4095
Treatment of pyridine-2-thiol (pytH) with H(2) (60 atm) in the presence of 5-methylpyridine-2-thiolate (5-mpyt)-bridged dinuclear Pt(III), Pt(II), or Pd(II) complexes (1 mol %) in DMF at 150 degrees C for 72 h leads to the formation of pyridine in 3-51% yield. From the (1)H NMR study of the exchange reactions and of the products under D(2) pressure, it is suggested that the catalytic reaction involves bimetallic activation of the pyt ligand followed by the liberation of pyridine and H(2)S. 相似文献
88.
Spectroscopic and crystallographic studies on the stability of self-assembled coordination nanotubes
Aoyagi M Tashiro S Tominaga M Biradha K Fujita M 《Chemical communications (Cambridge, England)》2002,(18):2036-2037
On complexation with (en)Pd(NO3)2, tetrakis(3,5-pyridine) ligand gives two isomeric coordination nanotubes, which are in slow equilibrium despite the presence of sixteen Pd-N bonds in the tube framework. 相似文献
89.
90.