全文获取类型
收费全文 | 259篇 |
免费 | 38篇 |
国内免费 | 59篇 |
专业分类
化学 | 269篇 |
晶体学 | 3篇 |
力学 | 12篇 |
综合类 | 5篇 |
数学 | 22篇 |
物理学 | 45篇 |
出版年
2023年 | 2篇 |
2022年 | 18篇 |
2021年 | 14篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 21篇 |
2017年 | 15篇 |
2016年 | 8篇 |
2015年 | 18篇 |
2014年 | 20篇 |
2013年 | 22篇 |
2012年 | 19篇 |
2011年 | 28篇 |
2010年 | 18篇 |
2009年 | 12篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 5篇 |
1959年 | 1篇 |
排序方式: 共有356条查询结果,搜索用时 15 毫秒
71.
Liu P Na N Huang L He D Huang C Ouyang J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(5):1438-1443
Novel amine-terminated silicon (Si) quantum dots (QDs) were synthesized and applied for the detection of human serum proteins on gels directly after polyacrylamide gel electrophoresis (PAGE). The diameter of these stable amine-terminated Si?QDs was in the range of 0.5-2.0 nm. In this study, the fluorescent imaging conditions, such as the buffer solution, pH value, buffer concentration and quantity of Si?QDs, were optimized and the possible mechanisms of Si?QDs-protein interaction were analyzed. The mode of Si?QDs and human serum albumin association was found to occur by hydrogen bond interactions; this was probably attributed to the interaction between the amino group of amine-terminated Si?QDs and the carboxyl group of proteins. Meanwhile, human serum proteins separated by native 1D and native 2D electrophoresis were detected by Si QD-based fluorescent imaging. Some proteins, such as isoform 1 of α-1-antitrypsin, complement C3 (Fragment) and hemopexin, which were identified by mass spectrometry (MS), were easily detected by using Si?QDs, but not with CBB-R250 staining. The Si?QDs-based fluorescent imaging technique with high resolution is a sensitive and dependable method for direct detection of human serum proteins, and has enormous potential in clinical diagnosis. 相似文献
72.
拜耳法赤泥矿物成分特殊,力学性能较差,平果铝赤泥堆场利用拜耳法赤泥筑坝在国内尚属首次。通过对拜耳法赤泥颗分情况、矿物及化学组成、物理力学特性等进行试验研究,认为赤泥中Fe2O3含量较高、粒径较细且属于级配不良的土; 结合平果铝赤泥堆场目前的运行情况,分析了赤泥堆场目前运行时存在的排水系统、赤泥固结等几个问题,指出了赤泥堆场堆存后期有可能由于赤泥排水缓慢而导致堆场底部赤泥长期被水浸泡,从而对堆场的稳定性造成一定影响。 相似文献
73.
Hydromagnesiation of alkynylsilanes 1 in diethyl ether gave (Z)‐α‐silylvinyl Grignard reagents 2 , which reacted with arylsulfenyl chlorides 3 to afford stereoselectively (E)‐α‐silylvinyl sulfides 4 in good yields. (E)‐α‐Silylvinyl sulfides 4 could undergo the cross‐coupling reactions with Grignard reagents in the presence of NiCl2(PPh3)2 to give stereoselectively (Z)‐1,2‐disubstituted vinylsilanes 5 . © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:644–647, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20165 相似文献
74.
Let(M~n, g)(n ≥ 3) be an n-dimensional complete Riemannian manifold with harmonic curvature and positive Yamabe constant. Denote by R and R?m the scalar curvature and the trace-free Riemannian curvature tensor of M, respectively. The main result of this paper states that R?m goes to zero uniformly at infinity if for p ≥ n, the L~p-norm of R?m is finite.As applications, we prove that(M~n, g) is compact if the L~p-norm of R?m is finite and R is positive, and(M~n, g) is scalar flat if(M~n, g) is a complete noncompact manifold with nonnegative scalar curvature and finite L~p-norm of R?m. We prove that(M~n, g) is isometric to a spherical space form if for p ≥n/2, the L~p-norm of R?m is sufficiently small and R is positive.In particular, we prove that(M~n, g) is isometric to a spherical space form if for p ≥ n, R is positive and the L~p-norm of R?m is pinched in [0, C), where C is an explicit positive constant depending only on n, p, R and the Yamabe constant. 相似文献
75.
The trifluoromethoxy(CF_3O) group has become a novel moiety in various fields because of its unique features. However, despite the promising applications, the synthesis of CF_3O-containing compounds is still a challenge due to indirect synthetical strategies and volatile reagent which is hard to handle. Until very recently, several innovative reagents were developed to facilitate the trifluoromethoxylation reaction and make CF_3O-containing compounds more accessible. This review mainly focuses on the recent advances in new trifluoromethoxylation reagents and their usage. 相似文献
76.
Risheng Wang Prof. Dr. Zhihua Peng Prof. Dr. Pingping Wu Jinzhi Lu Prof. Dr. Mark J. Rood Prof. Dr. Hongman Sun Prof. Dr. Jingbin Zeng Prof. Dr. Youhe Wang Prof. Dr. Zifeng Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(34):8694-8697
Soft template designing is the most promising strategy for the synthesis of zeolite nanosheets. MFI nanosheets directed by soft templates (containing long-chain alkyl groups or aromatic groups as hydrophobic component) can be found frequently; however, so far, MFI nanosheets synthesized by soft templates with aromatic heterocycle groups (e. g., s-triazine groups) are rare. Herein, a nanosheet-stacked hierarchical MFI zeolite (NSHM) has been synthesized by using a triply branched s-triazine-based surfactant as a bifunctional organic structure-directing agent. On the basis of a geometrical match relationship, a formation model has been proposed. Synthesized NSHM had abundant mesopores stacked by nanosheets and exhibited a high surface area (430 m2 ⋅ g−1). The 1 wt% Pd/NSHM attained a significant increase in yield of cyclohexanol/cyclohexanone mixture (from 66 to 85 %) in the oxidation of cyclohexane compared with Silicalite-1 and SBA-15 as supports. 相似文献
77.
78.
Head–Tail Asymmetry as the Determining Factor in the Formation of Polymer Cubosomes or Hexasomes in a Rod–Coil Amphiphilic Block Copolymer
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)
Xiaolin Lyu Anqi Xiao Wei Zhang Pingping Hou Kehua Gu Zhehao Tang Hongbing Pan Fan Wu Prof. Zhihao Shen Prof. Xing‐He Fan 《Angewandte Chemie (International ed. in English)》2018,57(32):10132-10136
The self‐assembly of a rod–coil amphiphilic block copolymer (ABCP) led to Im m and Pn m polymer cubosomes and p6mm polymer hexasomes. This is the first time that these structures are observed in a rod–coil system. By varying the hydrophobic chain length, the initial concentration of the polymer solution, or the solubility parameter of the mixed solvent, head–tail asymmetry is adjusted to control the formation of polymer cubosomes or hexasomes. The formation mechanism of the polymer cubosomes was also studied. This research opens up a new way for further study of the bicontinuous and inverse phases in different ABCP systems. 相似文献
79.
Dr. Jingtao Wang Pingping Chen Benbing Shi Prof. Weiwei Guo Prof. Mietek Jaroniec Prof. Shi‐Zhang Qiao 《Angewandte Chemie (International ed. in English)》2018,57(23):6814-6818
Lamellar membranes show exceptional molecular permeation properties of key importance for many applications. However, their design and development need the construction of regular and straight interlayer channels and the establishment of corresponding transport rate equation. The fabrication of a uniformly lamellar membrane is reported using double‐layered Ti3C2Tx MXenes as rigid building blocks. This membrane possesses ordered and straight 2 nm channels formed via a direct self‐stacking, in contrast to the conventional irregular ones from flexible sheets. Such channels permit precise molecular rejection and unparalleled molecular permeation. The permeance of water and organics by this membrane reached 2300 and 5000 L m?2 h?1 bar?1, respectively. The molecular transfer mechanism in confined nanochannels, and the corresponding model equation are established, paving a way to nanoscale design of highly efficient channeled membranes for transport and separation applications. 相似文献
80.
Pingping Gao Zhiyong Xie Ouyang Chun Tao Tao Xiaobo Wu Qizhong Huang 《Journal of Solid State Electrochemistry》2018,22(7):1971-1981
The Ni-P/TiN/PTFE (poly tetra fluoroethylene) composite coatings were prepared by electroless plating method on Ti plate, which was used as bipolar plates of proton exchange membrane fuel cells (PEMFCs). The morphology, crystallographic texture, electrochemical corrosion, contact resistance, and hydrophobic property of the Ti bipolar plates with coatings were investigated. The results revealed that Ni-P/TiN/PTFE coating had a dense surface morphology, uniform distribution of composite particles. Ti with coating showed 0.48 μA cm2 of corrosion current in the simulated solution of PEMFCs and 6 mΩ cm2 of interfacial contact resistance (ICR). The hydrophobicity test showed that the coating interface was flat and the wetting angle was 112.4°. In conclusion, The Ni-P/TiN/PTFE composite coatings exhibit superior improvement in corrosion resistance, interface hydrophobicity, and conductivity to Ni-P, Ni-P/TiN, and Ni-P/PTFE coatings. The Ni-P/TiN/PTFE coating was suited for bipolar plate surface modification of bipolar plates. 相似文献