全文获取类型
收费全文 | 154篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
化学 | 127篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 12篇 |
物理学 | 22篇 |
出版年
2023年 | 6篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 23篇 |
2011年 | 17篇 |
2010年 | 8篇 |
2009年 | 3篇 |
2008年 | 9篇 |
2007年 | 6篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有165条查询结果,搜索用时 31 毫秒
91.
Synthesis of Air‐ and Moisture‐Stable,Storable Chiral Oxorhenium Complexes and Their Application as Catalysts for the Enantioselective Imine Reduction
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Braja Gopal Das Rajender Nallagonda Dhananjay Dey Dr. Prasanta Ghorai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12601-12605
Air‐/moisture‐stable, crystalline, and storable chiral salicyloxazoline based oxorhenium(V) complexes have been synthesized and their catalytic application for the asymmetric reduction of ketimines using hydrosilane as hydride source is disclosed. A broad substrate scope, high yields, and excellent enantioselectivities (up to 99 %) are attained. Furthermore, the syntheses of enantiopure α‐amino esters, γ‐ and δ‐lactams, and isoindolinones have also been carried out using this methodology. Finally, the method has been applied to synthetic targets of pharmaceutical relevance, such as R‐(+)‐salsolidine and R‐(+)‐crispine A. 相似文献
92.
Singh C Ghorai PK Horsch MA Jackson AM Larson RG Stellacci F Glotzer SC 《Physical review letters》2007,99(22):226106
We perform atomistic and mesoscale simulations to explain the origin of experimentally observed stripelike patterns formed by immiscible ligands coadsorbed on the surfaces of gold and silver nanoparticles. We show that when the conformational entropy gained via this morphology is sufficient, microphase-separated stripelike patterns form. When the entropic gain is not sufficient, we instead predict bulk phase-separated Janus particles. We also show corroborating experimental results that confirm our simulational predictions that stripes form on flat surfaces as well as on curved nanoparticle surfaces. 相似文献
93.
A spectral element method for solving parabolic initial boundary value problems on smooth domains using parallel computers is presented in this paper. The space domain is divided into a number of shape regular quadrilaterals of size h and the time step k is proportional to h2. At each time step we minimize a functional which is the sum of the squares of the residuals in the partial differential equation, initial condition and boundary condition in different Sobolev norms and a term which measures the jump in the function and its derivatives across inter-element boundaries in certain Sobolev norms. The Sobolev spaces used are of different orders in space and time. We can define a preconditioner for the minimization problem which allows the problem to decouple. Error estimates are obtained for both the h and p versions of this method. 相似文献
94.
Ruchi Gaikwad Sk. Abdul Amin Nilanjan Adhikari Soumajit Ghorai Tarun Jha Shovanlal Gayen 《Structural chemistry》2018,29(4):1095-1107
Phenylindole is reported to be an interesting scaffold having promising cytotoxic activities and can overcome the cancer drug resistance possibly via binding to the colchicine binding site of tubulin. In order to find out the molecular fingerprints for the better cytotoxic activity of phenylindole derivatives, multiple validated chemometric modeling approaches namely hologram QSAR (HQSAR), Bayesian classification model, and pharmacophore mapping analyses were applied into a dataset of 102 phenylindole derivatives. The final HQSAR model shows good statistical significance (Q2?=?0.760; R2Train?=?0.868; R2Test?=?0.660), and the best pharmacophore hypothesis has the highest regression coefficient value (r?=?0.975) and the lowest RMS value of 0.679. Moreover, the Bayesian model is also statistically validated and robust to discriminate the cytotoxic and non-cytotoxic phenylindoles. These studies suggest that the amine group should be unsubstituted for retaining higher cytotoxicity. The pharmacophore mapping and Bayesian classification study suggest the importance of 2-phenyl group as a ring aromatic feature conducive to cytotoxicity. The steric and hydrophobic effect of long chain linear alkyl group has a positive influence on cytotoxicity as evidenced by the multi-QSAR study. Therefore, this multi-QSAR modeling reported here is beneficial in designing potential phenylindole cytotoxic agents in future. 相似文献
95.
Cinchonamine Squaramide Catalyzed Asymmetric aza‐Michael Reaction: Dihydroisoquinolines and Tetrahydropyridines
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)
Tarun Kumar Roy Biswajit Parhi Dr. Prasanta Ghorai 《Angewandte Chemie (International ed. in English)》2018,57(30):9397-9401
The first example of a chiral cinchona‐squaramide catalyzed enantioselective intramolecular aza‐Michael addition for the synthesis of dihydroisoquinolines and tetrahydropyridines has been developed. In general, good yields and excellent enantioselctivities were observed. Broad classes of Michael acceptors, such as enones, esters, thioesters, and Weinreb amides, were successful substrates. The possibility of recycling the catalysts has also been demonstrated. An oxidation of combined enamine and keto functionalities on chiral dihydroisoquinolines leads to a single diastereomer of an architecturally unprecedented tetracyclic core without loss in enantioselectivity. 相似文献
96.
Reddy Rajasekhar Reddy Satish Sonbarao Gudup Prasanta Ghorai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(48):15339-15343
An unprecedented enantioselective oxa‐Michael reaction of α‐tertiary alcohols using cinchona‐alkaloid‐based chiral bifunctional squaramide catalysts is reported. An oxidative dearomatization of phenol followed by an enantioselective oxa‐Michael addition sequence provided a broad array of chiral sterically hindered tetrahydrofurans and tetrahydropyrans attached to a cyclohexadienone moiety in spiro fashion. In general, good yields and excellent enantioselectivities (up to 99 %) were observed. The chiral oxo‐cycles obtained have easily been transformed into chromans without disturbing the enantioselectivity. 相似文献
97.
Ghorai Santu Chakraborty Priyanka Poria Swarup Bairagi Nandadulal 《Nonlinear dynamics》2020,100(1):749-762
Nonlinear Dynamics - Dispersal-induced pattern formation is important from both fundamental and application points of view. Spatial pattern in an ecological system can strongly depend on exogenous... 相似文献
98.
Electrolyte chemistry plays an important role in the transport properties of analytes through nanopores. Here, we report the translocation properties of the protein human serum transferrin (hSTf) in asymmetric LiCl salt concentrations with either positive (Ctrans/Ccis < 1) or negative chemical gradients (Ctrans/Ccis > 1). The cis side concentration was fixed at 4 M for positive chemical gradients and at 0.5 M LiCl for negative chemical gradients, while the trans side concentration varied between 0.5 to 4 M which resulted in six different configurations, respectively, for both positive and negative gradient types. For positive chemical gradient conditions, translocations were observed in all six configurations for at least one voltage polarity whereas with negative gradient conditions, dead concentrations where no events at either polarity were observed. The flux of Li+ and Cl− ions and their resultant cation or anion enrichment zones, as well as the interplay of electrophoretic and electroosmotic transport directions, would determine whether hSTf can traverse across the pore. 相似文献
99.
Cobalt(III)‐Catalyzed Intramolecular Cross‐Dehydrogenative C−H/X−H Coupling: Efficient Synthesis of Indoles and Benzofurans
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jayanta Ghorai Angula Chandra Shekar Reddy Prof. Dr. Pazhamalai Anbarasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16042-16046
An efficient cobalt(III)‐catalyzed intramolecular cross‐dehydrogenative C?H/N?H coupling of ortho‐alkenylanilines has been developed utilizing O2 as a terminal oxidant. The developed reaction tolerates various reactive functional groups and allows the synthesis of diverse indole derivatives in good to excellent yields. The method was successfully extended to the synthesis of benzofurans through the intramolecular cross‐dehydrogenative C?H/O?H coupling of ortho‐alkenylphenols. 相似文献
100.
Sobhan Roy Venugopal Rao Ravipati Suvankar Ghorai Mrinmay Chakrabarti Amit Kumar Das Ananta Kumar Ghosh 《Applied biochemistry and biotechnology》2012,168(5):1076-1085
Antheraea mylitta, a tasar silk-producing insect of Saturniidae family, expresses a fungal protease inhibitor named as A. mylitta fungal protease inhibitor-1 (AmFPI-1). AmFPI-1 inhibits alkaline protease of Aspergillus oryzae but its mechanism of action is not known. To understand the mode of inhibition of AmFPI-1 against the fungal protease, it was purified from the hemolymph of A. mylitta larvae and inhibitory activity against A. oryzae protease was studied. Kinetic analysis of purified AmFPI-1 on alkaline protease of A. oryzae showed that AmFPI-1 acts as a canonical-type competitive inhibitor with equilibrium dissociation constant (K i ) of 60?nM. Expression of AmFPI-1 in different body tissues of fifth instar A. mylitta larvae was determined by real-time PCR, and the highest expression was observed in fat body followed by integument, silk gland, and gut, indicating that AmFPI-1 has pleiotropic functions including protection from invading fungi. The cDNA of AmFPI-1 was expressed in Escherichia coli, and recombinant His-tagged fusion protein was purified by Ni-NTA chromatography. Recombinant AmFPI-1 showed inhibitory activity against A. oryzae protease and suggested its use in various biological applications to prevent proteolysis. 相似文献