全文获取类型
收费全文 | 3939篇 |
免费 | 870篇 |
国内免费 | 597篇 |
专业分类
化学 | 5168篇 |
晶体学 | 12篇 |
力学 | 8篇 |
综合类 | 26篇 |
物理学 | 192篇 |
出版年
2023年 | 47篇 |
2022年 | 67篇 |
2021年 | 96篇 |
2020年 | 261篇 |
2019年 | 167篇 |
2018年 | 170篇 |
2017年 | 134篇 |
2016年 | 251篇 |
2015年 | 288篇 |
2014年 | 322篇 |
2013年 | 433篇 |
2012年 | 341篇 |
2011年 | 302篇 |
2010年 | 249篇 |
2009年 | 224篇 |
2008年 | 252篇 |
2007年 | 235篇 |
2006年 | 221篇 |
2005年 | 223篇 |
2004年 | 186篇 |
2003年 | 261篇 |
2002年 | 111篇 |
2001年 | 90篇 |
2000年 | 60篇 |
1999年 | 61篇 |
1998年 | 39篇 |
1997年 | 71篇 |
1996年 | 64篇 |
1995年 | 47篇 |
1994年 | 28篇 |
1993年 | 19篇 |
1992年 | 32篇 |
1991年 | 14篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有5406条查询结果,搜索用时 31 毫秒
921.
H. Bargozin R. A. Hadadhania T. Y. Amiri 《Journal of Dispersion Science and Technology》2016,37(6):806-815
In this work, the influence of chemical heterogeneity on the stability of nanocolloidal systems is surveyed with a new method. Zone of influence as a very important parameter for chemical patch surveying is modeled for sphere and flat surface. Surface chemical heterogeneity with specified properties, size, and position are created by spherical coordinate integration method. Rippled sphere model is used to create roughness and the flat surface is created by changing two sphere radius ratio. Using the spherical coordinate system for modeling of surface roughness and chemical heterogeneity is very accurate and fast. Results show that the patches could destabilize the colloidal system at very small sizes. Surface roughness reduces the effect of chemical patches for destabilizing the colloidal system, and with increasing the size of roughness the total DLVO energy interaction increases. 相似文献
922.
Dr. Jong Wook Hong Yena Kim Dae Han Wi Seunghoon Lee Su‐Un Lee Young Wook Lee Prof. Sang‐Il Choi Prof. Sang Woo Han 《Angewandte Chemie (International ed. in English)》2016,55(8):2753-2758
A synthesis strategy for the preparation of ultrathin free‐standing ternary‐alloy nanosheets is reported. Ultrathin Pd‐Pt‐Ag nanosheets with a thickness of approximately 3 nm were successfully prepared by co‐reduction of the metal precursors in an appropriate molar ratio in the presence of CO. Both the presence of CO and the interplay between the constituent metals provide fine control over the anisotropic two‐dimensional growth of the ternary‐alloy nanostructure. The prepared Pd‐Pt‐Ag nanosheets were superior catalysts of ethanol electrooxidation owing to their specific structural and compositional characteristics. This approach will pave the way for the design of multicomponent 2D nanomaterials with unprecedented functions. 相似文献
923.
Use of a “Catalytic” Cosolvent,N,N‐Dimethyl Octanamide,Allows the Flow Synthesis of Imatinib with no Solvent Switch
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)
Jeffrey C. Yang Dawen Niu Bram P. Karsten Fabio Lima Prof. Dr. Stephen L. Buchwald 《Angewandte Chemie (International ed. in English)》2016,55(7):2531-2535
A general, efficient method for C?N cross‐coupling has been developed using N,N‐dimethyloctanamide as a catalytic cosolvent for biphasic continuous‐flow applications. The described method was used to generate a variety of biarylamines and was integrated into a two‐step sequence which converted phenols into biarylamines via either triflates or tosylates. Additionally, the method was applied to a three‐step synthesis of imatinib, the API of Gleevec, in good yield without the need of solvent switches. 相似文献
924.
Highly Unsaturated Platinum and Palladium Carbenes PtC3 and PdC3 Isolated and Characterized in the Gas Phase
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)
Dror M. Bittner Dr. Daniel P. Zaleski Dr. David P. Tew Dr. Nicholas R. Walker Prof.Dr. Anthony C. Legon 《Angewandte Chemie (International ed. in English)》2016,55(11):3768-3771
Carbenes of platinum and palladium, PtC3 and PdC3, were generated in the gas phase through laser vaporization of a metal target in the presence of a low concentration of a hydrocarbon precursor undergoing supersonic expansion. Rotational spectroscopy and ab initio calculations confirm that both molecules are linear. The geometry of PtC3 was accurately determined by fitting to the experimental moments of inertia of twenty‐six isotopologues. The results are consistent with the proposal of an autogenic isolobal relationship between O, Au+, and Pt atoms. 相似文献
925.
Dr. Suhua Li Ru‐Yi Zhu Dr. Kai‐Jiong Xiao Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2016,55(13):4317-4321
PdII‐catalyzed arylation of γ‐C(sp3)?H bonds of aliphatic acid‐derived amides was developed by using quinoline‐based ligands. Various γ‐aryl‐α‐amino acids were prepared from natural amino acids using this method. The influence of ligand structure on reactivity was also systematically investigated. 相似文献
926.
Theoretical Modelling and Facile Synthesis of a Highly Active Boron‐Doped Palladium Catalyst for the Oxygen Reduction Reaction
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)
Tat Thang Vo Doan Jingbo Wang Kee Chun Poon Desmond C. L. Tan Bahareh Khezri Prof. Richard D. Webster Prof. Haibin Su Prof. Hirotaka Sato 《Angewandte Chemie (International ed. in English)》2016,55(24):6842-6847
A highly active alternative to Pt electrocatalysts for the oxygen reduction reaction (ORR), which is the cathode‐electrode reaction of fuel cells, is sought for higher fuel‐cell performance. Our theoretical modelling reveals that B‐doped Pd (Pd‐B) weakens the absorption of ORR intermediates with nearly optimal binding energy by lowering the barrier associated with O2 dissociation, suggesting Pd‐B should be highly active for ORR. In fact, Pd‐B, facile synthesized by an electroless deposition process, exhibits 2.2 times and 8.8 times higher specific activity and 14 times and 35 times less costly than commercial pure Pd and Pt catalysts, respectively. Another computational result is that the surface core level of Pd is negatively shifted by B doping, as confirmed by XPS, and implies that filling the density of states related to the anti‐bonding of oxygen to Pd surfaces with excess electrons from B doping, weakens the O bonding to Pd and boosts the catalytic activity. 相似文献
927.
Cyclometalated Palladium(II) N‐Heterocyclic Carbene Complexes: Anticancer Agents for Potent In Vitro Cytotoxicity and In Vivo Tumor Growth Suppression
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. Tommy Tsz‐Him Fong Dr. Chun‐Nam Lok Dr. Clive Yik‐Sham Chung Dr. Yi‐Man Eva Fung Dr. Pui‐Keong Chow Pui‐Ki Wan Prof. Dr. Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2016,55(39):11935-11939
Palladium(II) complexes are generally reactive toward substitution/reduction, and their biological applications are seldom explored. A new series of palladium(II) N‐heterocyclic carbene (NHC) complexes that are stable in the presence of biological thiols are reported. A representative complex, [Pd(C^N^N)(N,N′‐nBu2NHC)](CF3SO3) ( Pd1 d , HC^N^N=6‐phenyl‐2,2′‐bipyridine, N,N′‐nBu2NHC=N,N′‐di‐n‐butylimidazolylidene), displays potent killing activity toward cancer cell lines (IC50=0.09–0.5 μm ) but is less cytotoxic toward a normal human fibroblast cell line (CCD‐19Lu, IC50=11.8 μm ). In vivo anticancer studies revealed that Pd1 d significantly inhibited tumor growth in a nude mice model. Proteomics data and in vitro biochemical assays reveal that Pd1 d exerts anticancer effects, including inhibition of an epidermal growth factor receptor pathway, induction of mitochondrial dysfunction, and antiangiogenic activity to endothelial cells. 相似文献
928.
Facet‐Dependent and Light‐Assisted Efficient Hydrogen Evolution from Ammonia Borane Using Gold–Palladium Core–Shell Nanocatalysts
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. Sourav Rej Chi‐Fu Hsia Tzu‐Yu Chen Fan‐Cheng Lin Prof. Jer‐Shing Huang Prof. Michael H. Huang 《Angewandte Chemie (International ed. in English)》2016,55(25):7222-7226
Au–Pd core–shell nanocrystals with tetrahexahedral (THH), cubic, and octahedral shapes and comparable sizes were synthesized. Similar‐sized Au and Pd cubes and octahedra were also prepared. These nanocrystals were used for the hydrogen‐evolution reaction (HER) from ammonia borane. Light irradiation can enhance the reaction rate for all the catalysts. In particular, Au–Pd THH exposing {730} facets showed the highest turnover frequency for hydrogen evolution under light with 3‐fold rate enhancement benefiting from lattice strain, modified surface electronic state, and a broader range of light absorption. Finite‐difference time‐domain (FDTD) simulations show a stronger electric field enhancement on Au–Pd core–shell THH than those on other Pd‐containing nanocrystals. Light‐assisted nitro reduction by ammonia borane on Au–Pd THH was also demonstrated. Au–Pd tetrahexahedra supported on activated carbon can act as a superior recyclable plasmonic photocatalyst for hydrogen evolution. 相似文献
929.
Efficient Palladium‐Assisted One‐Pot Deprotection of (Acetamidomethyl)Cysteine Following Native Chemical Ligation and/or Desulfurization To Expedite Chemical Protein Synthesis
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. Suman Kumar Maity Muhammad Jbara Shay Laps Prof. Ashraf Brik 《Angewandte Chemie (International ed. in English)》2016,55(28):8108-8112
The acetamidomethyl (Acm) moiety is a widely used cysteine protecting group for the chemical synthesis and semisynthesis of peptide and proteins. However, its removal is not straightforward and requires harsh reaction conditions and additional purification steps before and after the removal step, which extends the synthetic process and reduces the overall yield. To overcome these shortcomings, a method for rapid and efficient Acm removal using PdII complexes in aqueous medium is reported. We show, for the first time, the assembly of three peptide fragments in a one‐pot fashion by native chemical ligation where the Acm moiety was used to protect the N‐terminal Cys of the middle fragment. Importantly, an efficient synthesis of the ubiquitin‐like protein UBL‐5, which contains two native Cys residues, was accomplished through the one‐pot operation of three key steps, namely ligation, desulfurization, and Acm deprotection, highlighting the great utility of the new approach in protein synthesis. 相似文献
930.
Dr. Matthieu Jouffroy Prof. Dr. Dominique Armspach Prof. Dr. Dominique Matt Prof. Dr. Kohtaro Osakada Dr. Daisuke Takeuchi 《Angewandte Chemie (International ed. in English)》2016,55(29):8367-8370
Cationic PdII monophosphine complexes derived from α‐ and β‐cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to 13C NMR studies with 13C‐enriched CO, both complexes catalyze the formation of CO‐free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer. 相似文献