全文获取类型
收费全文 | 2075篇 |
免费 | 40篇 |
国内免费 | 3篇 |
专业分类
化学 | 1322篇 |
晶体学 | 24篇 |
力学 | 47篇 |
数学 | 382篇 |
物理学 | 343篇 |
出版年
2022年 | 29篇 |
2021年 | 26篇 |
2020年 | 30篇 |
2019年 | 27篇 |
2018年 | 26篇 |
2017年 | 35篇 |
2016年 | 40篇 |
2015年 | 32篇 |
2014年 | 55篇 |
2013年 | 106篇 |
2012年 | 102篇 |
2011年 | 104篇 |
2010年 | 68篇 |
2009年 | 66篇 |
2008年 | 127篇 |
2007年 | 105篇 |
2006年 | 93篇 |
2005年 | 85篇 |
2004年 | 76篇 |
2003年 | 56篇 |
2002年 | 65篇 |
2001年 | 28篇 |
2000年 | 25篇 |
1999年 | 14篇 |
1997年 | 14篇 |
1996年 | 34篇 |
1995年 | 24篇 |
1994年 | 29篇 |
1993年 | 23篇 |
1992年 | 24篇 |
1991年 | 20篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 27篇 |
1987年 | 27篇 |
1986年 | 15篇 |
1985年 | 34篇 |
1984年 | 38篇 |
1983年 | 24篇 |
1982年 | 41篇 |
1981年 | 32篇 |
1980年 | 23篇 |
1979年 | 21篇 |
1978年 | 33篇 |
1977年 | 20篇 |
1976年 | 23篇 |
1974年 | 16篇 |
1973年 | 31篇 |
1972年 | 13篇 |
1971年 | 12篇 |
排序方式: 共有2118条查询结果,搜索用时 328 毫秒
121.
Shady Farah Oren Aviv Natalia Laout Stanislav Ratner Nurit Beyth Abraham J. Domb 《先进技术聚合物》2014,25(6):689-692
Silica particles functionalized with quaternary ammonium groups were prepared by interpenetrating polyethylenimine (PEI) into silica particles and crosslinking with diiodopentane, followed by octyliodide alkylation and methyliodide quaternarization (S‐QA‐PEI). The synthesized S‐QA‐PEI particles were identified with a slight particle size increase of 2–3 µm. Different ratios of PEI:silica particles were prepared and analyzed. While silica particles are negatively charged, ?16.7 ± 5.11 mV, the prepared S‐QA‐PEI particles are positively charged, +50–60 mV. These particles were embedded in poly(ethylene vinyl acetate) and poly(ethylene methacrylic acid) coatings which exhibited strong antibacterial activity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
122.
Dr. Koushik Chandra Dr. Tapta Kanchan Roy Dr. Deborah E. Shalev Prof. Abraham Loyter Prof. Chaim Gilon Prof. R. Benny Gerber Prof. Assaf Friedler 《Angewandte Chemie (International ed. in English)》2014,53(36):9450-9455
We present a new approach for peptide cyclization during solid phase synthesis under highly acidic conditions. Our approach involves simultaneous in situ deprotection, cyclization and trifluoroacetic acid (TFA) cleavage of the peptide, which is achieved by forming an amide bond between a lysine side chain and a succinic acid linker at the peptide N‐terminus. The reaction proceeds via a highly active succinimide intermediate, which was isolated and characterized. The structure of a model cyclic peptide was solved by NMR spectroscopy. Theoretical calculations support the proposed mechanism of cyclization. Our new methodology is applicable for the formation of macrocycles in solid‐phase synthesis of peptides and organic molecules. 相似文献
123.
Rajan Patel Meena Kumari Abbul Bashar Khan 《Applied biochemistry and biotechnology》2014,172(8):3701-3720
Room temperatures ionic liquids are considered as miraculous solvents for biological system. Due to their inimitable properties and large variety of applications, they have been widely used in enzyme catalysis and protein stability and separation. The related information present in the current review is helpful to the researchers working in the field of biotechnology and biochemistry to design or choose an ionic liquid that can serve as a noble and selective solvent for any particular enzymatic reaction, protein preservation and other protein based applications. We have extensively analyzed the methods used for studying the protein–IL interaction which is useful in providing information about structural and conformational dynamics of protein. This can be helpful to develop and understanding about the effect of ionic liquids on stability and activity of proteins. In addition, the affect of physico-chemical properties of ionic liquids, viz. hydrogen bond capacity and hydrophobicity on protein stability are discussed. 相似文献
124.
Florent Jasinski Emeline Lobry Abraham Chemtob Céline Croutxe-Barghorn Loïc Vidal Ludovic Josien Jocelyne Brendlé Adrien Criqui 《Colloid and polymer science》2014,292(12):3095-3102
When finally processed to provide the function for which the latex was selected―binding, protecting, finishing―components such as surfactant, costabilizer or initiator become generally useless, not to say detrimental. In this study, we show that miniemulsion photopolymerization provides a suitable method to create latex without the apparent addition of these three compounds. Indeed, UV-driven monomer self-initiation can create initiating radicals without the aid of initiator, the fast in situ photogenerated polymer can hinder Ostwald ripening with the assistance of external costabilizer, and finally, UV-transparent clay can replace conventional surfactant to ensure colloidal stabilization. Each strategy has been developed individually before being combined together to end up with a unique miniemulsion procedure free of initiator, costabilizer and surfactant. Such approach paves the way to a simplified and environmentally improved pathway towards aqueous polymer dispersions. 相似文献
125.
Pambingal Rajan Sruthi Saithalavi Anas 《Journal of polymer science. Part A, Polymer chemistry》2020,58(8):1039-1061
The physicochemical properties of polymers are mainly dependent on the nature of polymer backbone and/or pendant groups linked to the main chain. Therefore, synthetic modification of these functional groups via post functionalization is an important approach for obtaining novel polymeric systems with improved properties and targeted applications. In this context, the synthetic modifications of nitrile group in polymers into various useful functionalities have received considerable attention and several interesting applications of the resulting polymers have been identified. The majority of the studies are based on Polyacrylonitrile (PAN), and some isolated examples of nitrile functionalization in copolymers such as Poly (Styrene-co-Acrylonitrile) (SAN), Poly (Acrylonitrile-co-Butadiene-co-Styrene (ABS) and Nitrile Rubber (NBR) are available. These synthetic modifications are mainly accomplished by the reactions such as Nucleophilic addition, cycloaddition, reduction, and hydrolysis using various reagents. These studies describing the post-polymerization modifications of nitrile group in polymers reported during the last three decades are covered in this review. 相似文献
126.
127.
Qualitative and semiquantitative study of the Liesegang rings formed by the reaction of oxalic acid and cadmium chloride in the acidic range of pH in silica hydrogel is made. The behaviour of Jablczynski's space constant and Morce-Pierce's time constant at various temperatures, pH and concentration of outer electrolyte is studied. The possible mechanisms for the above observed behaviour are suggested. The deviations from Isemura's general obserations are interprerted by considering two particular aspects, viz., comparatively larger crystals constituting the rings and the irreversibility of inner and outer electrolytes. 相似文献
128.
Back Cover: Yoctoliter Thermometry for Single‐Molecule Investigations: A Generic Bead‐on‐a‐Tip Temperature‐Control Module (Angew. Chem. Int. Ed. 13/2014)
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)
129.
Alyssa B. Sanders Jacob T. Zangaro Nakoa K. Webber Ryan P. Calhoun Elizabeth A. Richards Samuel L. Ricci Hannah M. Work Daniel D. Yang Kaitlyn R. Casey Joseph C. Iovine Gabriela Baker Taylor V. Douglas Sierra B. Dutko Thomas J. Fasano Sarah A. Lofland Ashley A. Rajan Mihaela A. Vasile Benjamin R. Carone Nathaniel V. Nucci 《Molecules (Basel, Switzerland)》2022,27(5)
Despite considerable advances in recent years, challenges in delivery and storage of biological drugs persist and may delay or prohibit their clinical application. Though nanoparticle-based approaches for small molecule drug encapsulation are mature, encapsulation of proteins remains problematic due to destabilization of the protein. Reverse micelles composed of decylmonoacyl glycerol (10MAG) and lauryldimethylamino-N-oxide (LDAO) in low-viscosity alkanes have been shown to preserve the structure and stability of a wide range of biological macromolecules. Here, we present a first step on developing this system as a future platform for storage and delivery of biological drugs by replacing the non-biocompatible alkane solvent with solvents currently used in small molecule delivery systems. Using a novel screening approach, we performed a comprehensive evaluation of the 10MAG/LDAO system using two preparation methods across seven biocompatible solvents with analysis of toxicity and encapsulation efficiency for each solvent. By using an inexpensive hydrophilic small molecule to test a wide range of conditions, we identify optimal solvent properties for further development. We validate the predictions from this screen with preliminary protein encapsulation tests. The insight provided lays the foundation for further development of this system toward long-term room-temperature storage of biologics or toward water-in-oil-in-water biologic delivery systems. 相似文献
130.
Khongsit Ansar Rajput Yudhishthir Singh Meena Sunita Sharma Rajan 《Journal of Analytical Chemistry》2022,77(3):295-300
Journal of Analytical Chemistry - Methods for the determination of mercury are described using gold nanoparticles functionalized with nitrogen containing cyclic molecules. Detection methods are... 相似文献