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51.
The simplest formulas connecting Jacobi elliptic functions with different modulus parameters were first obtained over two
hundred years ago by John Landen. His approach was to change integration variables in elliptic integrals. We show that Landen’s
formulas and their subsequent generalizations can also be obtained from a different approach, using which we also obtain several
new Landen transformations. Our new method is based on recently obtained periodic solutions of physically interesting non-linear
differential equations and remarkable new cyclic identities involving Jacobi elliptic functions. 相似文献
52.
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54.
Biswas HS Datta J Chowdhury DP Reddy AV Ghosh UC Srivastava AK Ray NR 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17413-17418
Hydrogenated diamond-like carbon (HDLC) has an atomically smooth surface that can be deposited on high-surface area substrata and functionalized with reactive chemical groups, providing an ideal substrate for protein immobilization. A synthetic sequence is described involving deposition and hydrogenation of DLC followed by chemical functionalization. These functional groups are reacted with amines on proteins causing covalent immobilization on contact. Raman measurements confirm the presence of these surface functional groups, and Fourier transform infrared spectroscopy (FTIR) confirms covalent protein immobilization. Atomic force microscopy (AFM) of immobilized proteins is reproducible because proteins do not move as a result of interactions with the AFM probe-tip, thus providing an advantage over mica substrata typically used in AFM studies of protein. HDLC offers many of the same technical advantages as oxidized graphene but also allows for coating large surface areas of biomaterials relevant to the fabrication of medical/biosensor devices. 相似文献
55.
[Structure: see text] Chenodeoxycholic acid based PET sensors for alkali metal ions have been immobilized on Merrifield resin and on Tentagel. The fluorescence of the sensor beads is enhanced upon binding the cations. The modular nature of the sensor allows designing different sensors based on this concept. 相似文献
56.
We propose a new self-assembly based strategy for the design of novel lanthanide based luminescent materials. In this approach a europium hydrogel is prepared and sensitization is achieved by doping the gel with pyrene in a non-coordinated fashion. 相似文献
57.
58.
Pei Y Lilly MJ Owen DJ D'Souza LJ Tang XQ Yu J Nazarbaghi R Hunter A Anderson CM Glasco S Ede NJ James IW Maitra U Chandrasekaran S Moos WH Ghosh SS 《The Journal of organic chemistry》2003,68(1):92-103
Type II diabetes mellitus is a chronic metabolic disorder that can lead to serious cardiovascular, renal, neurologic, and retinal complications. While several drugs are currently prescribed to treat type II diabetes, their efficacy is limited by mechanism-related side effects (weight gain, hypoglycemia, gastrointestinal distress), inadequate efficacy for use as monotherapy, and the development of tolerance to the agents. Consequently, combination therapies are frequently employed to effectively regulate blood glucose levels. We have focused on the mitochondrial sodium-calcium exchanger (mNCE) as a novel target for diabetes drug discovery. We have proposed that inhibition of the mNCE can be used to regulate calcium flux across the mitochondrial membrane, thereby enhancing mitochondrial oxidative metabolism, which in turn enhances glucose-stimulated insulin secretion (GSIS) in the pancreatic beta-cell. In this paper, we report the facile synthesis of benzothiazepines and derivatives by S-alkylation using 2-aminobenzhydrols. The syntheses of other bicyclic analogues based on benzothiazepine, benzothiazecine, benzodiazecine, and benzodiazepine templates are also described. These compounds have been evaluated for their inhibition of mNCE activity, and the results from the structure-activity relationship (SAR) studies are discussed. 相似文献
59.
An M Maitra U Neidlein U Bartlett PA 《Journal of the American Chemical Society》2003,125(42):12759-12767
A chemical synthesis of both diastereomers of the tetrahedral intermediate involved in 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) catalysis has been accomplished. Combination of methyl dibromopyruvate with a protected shikimic acid derivative, phosphorylation, and lactonization afforded the intermediates (S)-15 and (R)-15, whose configurations were assigned by NMR. After introduction of the 3-phosphate group and deprotection, photoinitiated radical debromination of the dibromo analogues (S)-5 and (R)-5 was accomplished with tributyltin hydride in mixed aqueous solvents in the presence of surfactant to give the pyruvate ketal phosphates (R)-TI and (S)-TI, respectively. These compounds are stable at high pH, but decompose at pH 7 with a half-life of ca. 10 min. (R)-TI proved to be inert to EPSPS, while (S)-TI was converted by the enzyme to a mixture of 5-enolpyruvylshikimate 3-phosphate, shikimate 3-phosphate, and phosphoenolpyruvate. The demonstration that the enzymatic intermediate possesses the S-configuration at the ketal center confirms the mechanism as an anti addition followed by a syn elimination. Furthermore, it appears that the syn stereochemistry of the second step requires the phosphate leaving group to serve as the base in catalyzing its own elimination. 相似文献
60.
Manindranath Bera Prasant Kumar Nanda Uday Mukhopadhyay Debashis Ray 《Journal of Chemical Sciences》2004,116(3):151-158
Low-temperature stoichiometric Schiff base reaction in air in 3:1 mole ratio between benzaldehyde and triethylenetetramine
(trien) in methanol yields a novel tetraaza μ-bis (bidentate) acyclic ligand L. It was characterized by elemental analysis, IR, EI mass and NMR (1H and13C) spectra. The formation of a five-membered imidazolidine ring from the ethylenediamine backbone as a spacer-cumbridging
unit gives rise to a new type of imidazolidine-bridged ligand. A geometric optimisation was made of the synthesized ligand
and its complexes by the method of molecular mechanics (MM2) method in order to establish the stable conformations. This hitherto
unknown tetraaza acyclic ligand affords new cationic dicopper(I/I) and dicopper(II/II) complexes in good yield. Dicopper(II/II)
complex displays weakd-d transition bands in the visible region, while dicopper(I/I) complex displays strong MLCT band in the same region. Both the
dinuclear complexes are of non-intimate nature and show interesting solution electrochemical behaviour. EPR spectral study
of μ-bis (imidazolidino) bridged dicopper(II/II) complex also supports the non-communicative nature of the two copper centres within
the same molecule 相似文献