全文获取类型
收费全文 | 345篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 245篇 |
晶体学 | 1篇 |
力学 | 8篇 |
数学 | 64篇 |
物理学 | 46篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 2篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 16篇 |
2013年 | 19篇 |
2012年 | 26篇 |
2011年 | 37篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 29篇 |
2007年 | 33篇 |
2006年 | 30篇 |
2005年 | 18篇 |
2004年 | 19篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有364条查询结果,搜索用时 31 毫秒
51.
Hyeong In Choi Sungjin Lee Hwan Pyo Moon Nam-Sook Wee Daehoon Kim Song-Hwa Kwon 《Entropy (Basel, Switzerland)》2021,23(7)
It is known that a variant of Ising model, called Seeded Ising Model, can be used to recover the information content of a biometric template from a fraction of information therein. The method consists in reconstructing the whole template, which is called the intruder template in this paper, using only a small portion of the given template, a partial template. This reconstruction method may pose a security threat to the integrity of a biometric identity management system. In this paper, based on the Seeded Ising Model, we present a systematic analysis of the possible security breach and its probability of accepting the intruder templates as genuine. Detailed statistical experiments on the intruder match rate are also conducted under various scenarios. In particular, we study (1) how best a template is divided into several small pieces called partial templates, each of which is to be stored in a separate silo; (2) how to do the matching by comparing partial templates in the locked-up silos, and letting only the results of these intra-silo comparisons be sent to the central tallying server for final scoring without requiring the whole templates in one location at any time. 相似文献
52.
Hui-Ming Wee Wan-Tsu Wang Ming-Chang Lee Leopoldo Eduardo Cárdenas-Barrón 《Applied Mathematical Modelling》2013,37(14-15):7876-7882
This paper presents an alternative approach to solve a finite horizon production lot sizing model with backorders using Cauchy-Bunyakovsky-Schwarz Inequality. The optimal batch size is derived from a sequence number of batches. We prove that a constant batch size policy with one fill rate is better than the variable batch sizes with variable fill rates. Finally, a practical approach is proposed to find the optimal solutions for a discrete planning horizon and discrete batch sizes. 相似文献
53.
54.
Zhenghua Li Chengbin Li Su Bin Park Gyoung Hee Hong Jin Seo Park Byung Jin Song Chul Wee Lee Ji Man Kim 《Research on Chemical Intermediates》2018,44(6):3687-3695
Oxidative desulfurization (ODS) of organic compounds containing sulfur element from a model oil was performed using tungsten oxide catalysts supported on mesoporous silica with cubic Ia3d mesostructure, well-defined mesopores (7.2 nm), high surface area (719 m2/g), and three-dimensional pore network (WO x /KIT-6). The prepared WO x /KIT-6 catalysts (5–20 wt% WO x ) were characterized by X-ray diffraction analysis, N2 sorption measurements, electron microscopy, H2-temperature programmed reduction, Raman spectroscopy, and thermogravimetric analysis. Among the mesoporous catalysts, 10 wt% WO x /KIT-6 exhibited the best catalytic performance. Sulfur-containing organic compounds, such as dibenzothiophene, 4,6-dimethyldibenzothiophene, and benzothiophene, were completely (100 %) removed from the model oil over 10 wt% WO x /KIT-6 catalyst in 2 h. In addition, the catalyst could be reused several times with only slight decrease in catalytic activity. 相似文献
55.
Plasmonic Hotspots in Air: An Omnidirectional Three‐Dimensional Platform for Stand‐Off In‐Air SERS Sensing of Airborne Species
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)
Gia Chuong Phan‐Quang Dr. Hiang Kwee Lee Hao Wen Teng Charlynn Sher Lin Koh Barnabas Qinwei Yim Dr. Eddie Khay Ming Tan Wee Lee Tok Dr. In Yee Phang Prof. Dr. Xing Yi Ling 《Angewandte Chemie (International ed. in English)》2018,57(20):5792-5796
Molecular‐level airborne sensing is critical for early prevention of disasters, diseases, and terrorism. Currently, most 2D surface‐enhanced Raman spectroscopy (SERS) substrates used for air sensing have only one functional surface and exhibit poor SERS‐active depth. “Aerosolized plasmonic colloidosomes” (APCs) are introduced as airborne plasmonic hotspots for direct in‐air SERS measurements. APCs function as a macroscale 3D and omnidirectional plasmonic cloud that receives laser irradiation and emits signals in all directions. Importantly, it brings about an effective plasmonic hotspot in a length scale of approximately 2.3 cm, which affords 100‐fold higher tolerance to laser misalignment along the z‐axis compared with 2D SERS substrates. APCs exhibit an extraordinary omnidirectional property and demonstrate consistent SERS performance that is independent of the laser and analyte introductory pathway. Furthermore, the first in‐air SERS detection is demonstrated in stand‐off conditions at a distance of 200 cm, highlighting the applicability of 3D omnidirectional plasmonic clouds for remote airborne sensing in threatening or inaccessible areas. 相似文献
56.
Accessing Frustrated Lewis Pair Chemistry from a Spectroscopically Stable and Classical Lewis Acid‐Base Adduct
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)
Dr. Timothy C. Johnstone Gabriel N. J. H. Wee Prof. Dr. Douglas W. Stephan 《Angewandte Chemie (International ed. in English)》2018,57(20):5881-5884
B(C6F5)3 and P(MeNCH2CH2)3N form a classical Lewis adduct, (C6F5)3BP(MeNCH2CH2)3N. Although (C6F5)3BP(MeNCH2CH2)3N does not exhibit spectroscopic evidence of dissociation into its constituent acid and base, products of frustrated Lewis pair (FLP) addition reactions are seen with PhNCO, PhCH2N3, PhNSO, and CO2. Computational studies show that thermal access to the dissociated acid and base permits FLP reactivity to proceed. These results demonstrate that FLP reactivity extends across the entire continuum of equilibria governing Lewis acid‐base adducts. 相似文献
57.
Cobalt-catalyzed hydrogen desorption from the LiNH2-LiBH4 system 总被引:1,自引:0,他引:1
Tang WS Wu G Liu T Wee AT Yong CK Xiong Z Hor AT Chen P 《Dalton transactions (Cambridge, England : 2003)》2008,(18):2395-2399
A doping of 5 wt% CoCl2 considerably decreases the dehydrogenation temperature of a mixture of LiNH2 and LiBH4. More that 8 wt% of hydrogen can be released at ca. 155 degrees C. X-Ray absorption near edge structure (XANES) spectroscopy indicated the formation of metallic Co after ball milling CoCl2 with LiNH2 and LiBH4. Extended X-ray absorption fine structure (EXAFS) spectroscopy measurements revealed that Co particles have poor crystallinity and are finely dispersed in the sample, which could lead to a high catalytic efficiency. 相似文献
58.
Palladium nanoparticles stabilized by an ionic polymer and ionic liquid: a versatile system for C-C cross-coupling reactions 总被引:1,自引:0,他引:1
Highly stable palladium nanoparticles (Pd NPs), protected by an imidazolium-based ionic polymer (IP) in a functionalized ionic liquid (IL), have been prepared and characterized by transmission electron microscopy (TEM). These Pd NPs are excellent precatalysts for Suzuki, Heck, and Stille coupling reactions and can be stored without undergoing degradation for at least 2 years. The NP-IP-IL system may therefore be considered as an alternative to the traditional palladium on carbon (Pd/C) precatalyst employed in many C-C coupling reactions, also allowing reactions to be conducted under "solvent-free" conditions. 相似文献
59.
Thiophene molecule selectively binds to the adjacent adatom-rest atom pair on the Si(111)-(7x7) surface through its alpha-carbon atoms, leading to the covalent attachment of a C-S-C linkage and remaining C=C (beta-carbon) bond onto the surface. Photoemission studies show that Cu atom readily adsorbs onto the S atom of the functional group to form the Cu-S molecular anchor in two forms: one points away from the thiophene C=C group; the other points toward the C=C group. 相似文献
60.
Lau HF Ang PC Ng VW Kuan SL Goh LY Borisov AS Hazendonk P Roemmele TL Boeré RT Webster RD 《Inorganic chemistry》2008,47(2):632-644
The reaction of the 1,2,3,5-dithiadiazolyls (4-R-C(6)H(4)CN(2)S(2))(2) (R = Me, 2a; Cl, 2b; OMe, 2c; and CF3, 2d) and (3-NC-5-tBu-C(6)H(3)CN(2)S(2))(2) (2e) with [CpCr(CO)(3)](2) (Cp = eta(5)-C(5)H(5)) (1) at ambient temperature respectively yielded the complexes CpCr(CO)(2)(eta(2)-S(2)N(2)CC(6)H(4)R) (R = 4-Me, 3a; 4-Cl, 3b; 4-OMe, 3c; and 4-CF(3), 3d) and CpCr(CO)(2)(eta(2)-S(2)N(2)CC(6)H(3)-3-(CN)-5-(tBu)) (3e) in 35-72% yields. The complexes 3c and 3d were also synthesized via a salt metathesis method from the reaction of NaCpCr(CO)(3) (1B) and the 1,2,3,5-dithiadiazolium chlorides 4-R-C(60H(4)CN(2)S(2)Cl (R = OMe, 8c; CF(3), 8d) with much lower yields of 6 and 20%, respectively. The complexes were characterized spectroscopically and also by single-crystal X-ray diffraction analysis. Cyclic voltammetry experiments were conducted on 3a-e, EPR spectra were obtained of one-electron-reduced forms of 3a-e, and variable temperature 1H NMR studies were carried out on complex 3d. Hybrid DFT calculations were performed on the model system [CpCr(CO)(2)S(2)N(2)CH] and comparisons are made with the reported CpCr(CO)(2)(pi-allyl) complexes. 相似文献