全文获取类型
收费全文 | 641篇 |
免费 | 26篇 |
国内免费 | 3篇 |
专业分类
化学 | 340篇 |
晶体学 | 11篇 |
力学 | 10篇 |
数学 | 29篇 |
物理学 | 280篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 18篇 |
2018年 | 18篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 31篇 |
2013年 | 60篇 |
2012年 | 36篇 |
2011年 | 52篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 30篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 26篇 |
2004年 | 14篇 |
2003年 | 9篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1938年 | 2篇 |
排序方式: 共有670条查询结果,搜索用时 171 毫秒
661.
Tanmay Dutta Arindam Bhattacharjee Uddalak Majumdar Saugata Sinha Ray Rupam Sahoo Sanjay Ghosh 《Applied biochemistry and biotechnology》2010,162(5):1238-1248
In this study, alkaliphilic family G/11 xylanase from alkali-tolerant filamentous fungi Penicillium citrinum MTCC 6489 was used as a model system to gain insight into the molecular aspects of unfolding/refolding of alkaliphilic glycosyl
hydrolase protein family. The intrinsic protein fluorescence suggested a putative intermediate state of protein in presence
of 2 M guanidium hydrochloride (GdmCl) with an emission maximum of 353 nm. Here we studied the refolding of GdmCl-denatured
alkaline xylanase in the presence and the absence of a multimeric chaperone protein α-crystallin to elucidate the molecular
mechanism of intramolecular interactions of the alkaliphilic xylanase protein that dictates its extremophilic character. Our
results, based on intrinsic tryptophan fluorescence and hydrophobic fluorophore 8-anilino-1- naphthalene sulfonate-binding
studies, suggest that α-crystallin formed a complex with a putative molten globule-like intermediate in the refolding pathway
of xylanase in an ATP-independent manner. A 2 M GdmCl is sufficient to denature alkaline xylanase completely. The hydrodynamic
radius (RH) of a native alkaline xylanase is 4.0, which becomes 5.0 in the presence of 2 M GdmCl whereas in presence of the higher concentration
of GdmCl RH value was shifted to 100, indicating the aggregation of denatured xylanase. The α-crystallin·xylanase complex exhibited the
recovery of functional activity with the extent of ~43%. Addition of ATP to the complex did not show any significant effect
on activity recovery of the denatured protein. 相似文献
662.
Papiya Bhattacharjee 《Algebra Universalis》2009,62(1):133-149
An extension G ≤ H of lattice-ordered groups is said to be a rigid extension if for each ${h \in H}An extension G ≤ H of lattice-ordered groups is said to be a rigid extension if for each h ? H{h \in H} there exists a g ? G{g \in G} such that h
⊥⊥ = g
⊥⊥. In this paper, we will define rigid extensions and some other generalizations in the context of algebraic frames satisfying
the FIP. One of the main results is a characterization of rigid extensions using d-elements of the frame. We also show that a rigid extension between two algebraic frames satisfying the FIP will induce a
homeomorphism between their corresponding minimal prime spaces with respect to both the hull-kernel topology and the inverse
topology. Moreover, basic open sets map to basic open sets. 相似文献
663.
Amrita Mandal Anindita Bose Sreemanta Mitra Anindya Datta Sourish Banerjee Dipankar Chakravorty 《Journal of magnetism and magnetic materials》2012
Nanoplates of NiS with thickness 0.6 nm were grown within the crystal channels of Na-4 mica. The thickness of the nanoplates is confirmed by atomic force microscopy. The nanocomposites exhibited multiferroic (both ferromagnetic and ferroelectric) behavior at room temperature. Ferromagnetism was adduced to an increase of surface defects as a result of the two-dimensional configuration of the sample. Ferroelectric behavior was explained as arising due to a small distortion in the crystal structure of NiS grown within the Na-4 mica channels. This was substantiated by the refined values of lattice constants as determined by profile matching of X-ray data by a computer program. A magnetodielectric effect was also observed in this nanocomposite with a change of 0.77% in the dielectric constant for a magnetic field of 0.6 T. 相似文献
664.
S. Archambault E. Behnke P. Bhattacharjee S. Bhattacharya X. Dai M. Das A. Davour F. Debris N. Dhungana J. Farine S. Gagnebin G. Giroux E. Grace C.M. Jackson A. Kamaha C. Krauss S. Kumaratunga M. Lafrenière M. Laurin I. Lawson L. Lessard I. Levine C. Levy R.P. MacDonald D. Marlisov J.-P. Martin P. Mitra A.J. Noble M.-C. Piro R. Podviyanuk S. Pospisil S. Saha O. Scallon S. Seth N. Starinski I. Stekl U. Wichoski T. Xie V. Zacek 《Physics letters. [Part B]》2012
665.
An “off-on” rhodamine-based fluorescence probe for the selective signaling of Cu(II) and Fe(III) has been designed and synthesized.
The optical properties of this compound have been investigated in acetonitrile-water (1:1) binary solution. Very interestingly,
this compound showed sensitivity and selectivity towards Cu(II) during absorption process and towards Fe(III) during emission
process. So this is a nice example of an excellent dual chemosensor for two biologically/physiologically very important transition metal ions using only the two very different techniques
(absorption and emission); both cases displayed only intensity enhancement. 相似文献
666.
Hossein Shabany Robert Pajewski Ernesto Abel Anindita Mukhopadhyay George W. Gokel 《Journal of heterocyclic chemistry》2001,38(6):1393-1400
The preparation of novel tris(macrocycle)s that transport Na+ through phospholipid bilayers is reported. All of the reported structures have the following structural elements: sidechain‐macrocycle‐spacer‐macro‐cycle‐spacer‐macrocycle‐sidechain. The overall extension of the channel system is defined by the lengths of the spacer chains. The flexible sidearms are thought to be aligned with the lipid axis and opposite to the spacer chains. To the extent the spacer chains contribute to organization of the structure and isolation of the cation‐containing pore from the surrounding lipid chains, more hydrophobic chains are expected to enhance cation transport. A comparison of C12H25<N18N>(CH2)12<N18N>(CH2)12<N18N> C12H25, 1, with (C12H25)2N(CH2)2<N18N>(CH2)12<N18N>(CH2)12<N18N>(CH2)2N(C12H25)2, 11, shows that the Na+ transport is, indeed, enhanced. 相似文献
667.
A. Basu J.K. Bhattacharjee S. Ramaswamy 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(4):725-730
We show that a recently proposed [J. Fleischer, P.H. Diamond, Phys. Rev. E 58, R2709 (1998)] one-dimensional Burgers-like model for magnetohydrodynamics (MHD) is in effect identical to existing models
for drifting lines and sedimenting lattices. We use the model to demonstrate, contrary to claims in the literature, that the
energy spectrum of MHD turbulence should be independent of mean magnetic field and that cross-correlations between the noise
sources for the velocity and magnetic fields cannot change the structure of the equations under renormalisation. We comment
on the scaling and the multiscaling properties of the stochastically forced version of the model.
Received 29 October 1998 and Received in final form 8 December 1998 相似文献
668.
669.
Aditya Kherudkar Angana Bhattacharjee Akash Nawkhare Soumi Mukherjee Sukhendu Pramanick Dr. Joydev K. Laha 《Chemical record (New York, N.Y.)》2023,23(10):e202300063
Aldehydes serve as the key functional group in organic synthesis and are valuable intermediates. The various advanced methods of direct formylation reactions have been reviewed in this article. Overcoming the drawbacks of the traditional methods of formylation, newer methods involving homo and heterogenous catalysts, one pot reactions, solvent free techniques are elaborated, which can be performed under mild conditions and using inexpensive resources. 相似文献
670.
Piyush Kumar Tanmoy Bhattacharjee Manishkumar Pandey Arti Hole Arvind Ingle C. Murali Krishna 《Journal of Raman spectroscopy : JRS》2016,47(11):1318-1326
Oral cancer is a major cause of mortality in South Asian men owing to rampant tobacco abuse. Cancers are also reported in non‐tobacco habitués, especially women, attributed to chronic irritations from irregular/sharp teeth, improper fillings, and poorly fit dentures. Conventional screening approaches are shown to be effective for high‐risk groups (tobacco/alcohol habitués). Raman spectroscopy (RS) is being extensively explored as an alternate/adjunct tool for diagnosis and management of oral cancers. In a previous Raman study on sequential oral carcinogenesis using hamster buccal pouch model, misclassifications between spectra from control and carcinogen [7,12‐dimethylbenz(a)anthracene (DMBA)]‐treated tissues were observed. Histopathology of some control tissues suggested pathological changes, attributable to repeated forceps‐induced irritations/trauma during animal handling. To explore these changes, in the present study, we recorded spectra from three different types of controls – vehicle control (n = 45), vehicle contralateral (n = 45), and DMBA contralateral (n = 70) – exposed to varying degree of forceps handling, along with DMBA‐treated pouches (n = 70) using a 14‐week carcinogenesis protocol. Spectra certified on the basis of histopathology and abnormal cell proliferation (cyclin D1 expression) were used to build models that were evaluated by independent test spectra from an exclusive set of DMBA‐treated and control animals. Many DMBA‐contralateral, vehicle‐control, and vehicle‐contralateral spectra were identified as higher pathologies, which subsequently corroborated with histopathology/cyclin D1 expression. Repeated forceps‐mediated injuries/irritations, during painting and animal handling, may elicit inflammatory responses, leading to neoplasm. The findings of the study suggest that RS could identify micro‐changes. Further, RS‐based in vivo imaging can serve as a promising label‐free tool for screening even in the non‐habitué population where conventional screening is shown to be not effective. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献