全文获取类型
收费全文 | 140篇 |
免费 | 4篇 |
专业分类
化学 | 90篇 |
晶体学 | 8篇 |
力学 | 6篇 |
数学 | 10篇 |
物理学 | 30篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有144条查询结果,搜索用时 15 毫秒
1.
Shaginian A Patel M Li MH Flickinger ST Kim C Cerrina F Belshaw PJ 《Journal of the American Chemical Society》2004,126(51):16704-16705
We describe the development of photolabile protecting groups based on the 3,4,5-trimethoxyphenacyl group (TMP). Orthogonal safety-catches were created by introducing an acid-activatible dimethyl ketal (AA-TMP) and an oxidatively activatible 1,3-dithiane (OA-TMP) into the photolabile TMP group. We demonstrate the application of these protecting groups in light-directed synthesis of small molecule microarrays with diversity elements radially attached to a hydroxyproline scaffold. 相似文献
2.
Mukul Biswas Madhusudan Banerjee Mrinal M. Maiti 《Journal of polymer science. Part A, Polymer chemistry》1984,22(9):1997-2004
Copper(II)-exchanged-13X molecular sieves, prepared from four copper(II) salts, namely, sulfate, nitrate, chloride, and acetate, and their activities in the polymerization of N-vinylcarbazole at a fixed copper ion exchange level were studied. From the kinetic characteristics of polymerization it was established that the variation in activities of the Cu-exchanged sieves is due primarily to the difference in the pH of the original salt solution, which is responsible for the varying degree of proton exchange with the zeolite during copper ion exchange. A first-order dependence of the rate of polymerization was observed with respect to H+ ion concentration of the original copper-salt solution. It was further established that the rate of polymerization of exchanged copper ion, at a hypothetical zero proton concentration, is low. A mechanism of polymerization of NVC on copper-exchanged-13X zeolite was suggested on the basis of the results obtained. 相似文献
3.
Mukul Biswas Madhusudan Banerjee Mrinal M. Maiti 《Journal of polymer science. Part A, Polymer chemistry》1985,23(10):2631-2646
Kinetics of polymerization of N-vinylcarbazole over Co(II)-13X molecular sieves in toluene have been studied. The rate of polymerization (Rp) has been found to be second order with respect to percent exchange level of Co(II) and also to the NVC concentration at all the reaction temperatures of 40, 50 and 60°C. The rate increases with decreasing pH of the original exchanging salt solution up to a pH of about 3.5, beyond which it falls. The overall activation energy of polymerization has been found to decrease with increase in monomer concentration, exchange level of Co(II), and the hydrogen ion concentration of the original exchange solution. Average degree of polymerization also follows a similar trend. A mechanism of polymerization involving simultaneous propagation on both metal ion Co(II) and proton on a zeolite surface has been suggested. The two propagation routes are characterized by an average activation energy of 10.36 kcal/mol and 5.40 kcal/mol on the metal ion and proton centers, respectively. 相似文献
4.
5.
Sarvin Hossien Saraf Reza Ghiasi 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(5):1047-1052
Russian Journal of Physical Chemistry A - In this study, using the B3LYP* method, quantum chemical computations were applied for analyzing the effects of solvent on the electronic spectrum features... 相似文献
6.
Kamlesh Madhusudan Makwana Dr. Radhakrishnan Mahalakshmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):4147-4156
A popular strategy in the de novo design of stable β‐sheet structures for various biomedical applications is the incorporation of aromatic pairs at the non‐hydrogen‐bonding (NHB) position. However, it is important to explicitly understand how aryl pair packing at the NHB region is coordinated with backbone structural rearrangements, and to delineate the benefits and drawbacks associated with stereopositional choice of dissimilar aromatic pairs. Here, we probe the consequences of flipped Trp/Tyr pairs by using engineered permutants at the NHB position of dodecapeptide β‐hairpins, proximal and distal to the turn. Extensive conformational analysis of these peptides using NMR and CD spectroscopy reveal that a classic Edge‐to‐Face and Face‐to‐Edge geometry at the proximal and distal aromatic pairs, respectively, in YW‐WY, is the most stabilizing. Such a preferred packing geometry in YW‐WY results in a highly twisted β‐sheet backbone, with Trp always providing a ‘Face’ orientation to its dissimilar aromatic partner Tyr. Flipping the proximal and/or distal aromatic pair distorts the ideal T‐shaped geometry, and results in alternate aryl arrangements that can adversely affect strand twist and β‐sheet stability. Our study reveals the existence of a strong stereopositional influence on the packing of dissimilar aromatic pairs. Our findings highlight the importance of modeling physical interaction forces while designing protein and peptide structures for functional applications. 相似文献
7.
Synthesis of nine new benzimidazole derivatives was reported. The products were identified by 1H NMR, mass spectroscopy, and infrared spectroscopy. 相似文献
8.
Priyanka Dixit Avinash C. Tripathi Shailendra K. Saraf 《Journal of heterocyclic chemistry》2013,50(6):1431-1436
A novel series of chromen‐2‐ones containing pyrazole, isoxazole, oxazine, and thiazine substitutions have been synthesized by reacting 3‐[3‐(4‐chloro‐phenyl)‐acryloyl]‐chromen‐2‐one and 3‐[3‐(3‐methoxy‐phenyl)‐acryloyl]‐chromen‐2‐one with various cyclizing agents such as hydrazine, phenylhydrazine, urea, and thiourea. The structures of all the synthesized compounds were confirmed by the use of IR, 1H‐NMR, mass spectroscopy, and elemental analysis data. All the newly synthesized compounds were evaluated for their anti‐inflammatory activity at a dose of 100 mg/kg body weight in carrageenan‐induced rat paw edema model. The entire series of the compounds exhibited moderate to good anti‐inflammatory activity, with the percentage inhibition of edema formation ranging from 39.99 to 63.15 against the reference drug ibuprofen (100 mg/kg) that showed 78.96% inhibition at the third hour. Compounds 3a , 3c , and 3d showed good inhibitory activity, whereas compounds 3b , 3e , 3f , and 3j showed moderate inhibitory activity at the third hour. 相似文献
9.
Fatima Gul Naz Paliwal Sarvesh K. Saraf Shailendra K. 《Russian Journal of General Chemistry》2021,91(2):285-293
Russian Journal of General Chemistry - A number of novel 7-chloro-4-aminoquinoline derivatives have been efficiently synthesized by nucleophilic aromatic substitution reaction of... 相似文献
10.