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101.
Gholamhossein Mohammadnezhad Mostafa M. Amini Vratislav Langer 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(2):m44-m47
Two distinct polymorphs of bis(μ2‐methylquinolin‐8‐olato)‐κ3N,O:O;κ3O:N,O‐bis[(isothiocyanato‐κN)lead(II)], [Pb2(C10H8NO)2(NCS)2], (I), forming dinuclear complexes from a methanolic solution containing lead(II) nitrate, 2‐methylquinolin‐8‐ol (M‐Hq) and KSCN, crystallized concomitantly as colourless prisms [form (Ia)] and long thin colourless needles [form (Ib)]. In both cases, the complexes lie across a centre of inversion. The polymorphs differ substantially in their conformation and in their interactions, viz. Pb...S and π–π for form (Ia) and Pb...S, Pb...π and C—H...π for form (Ib). 相似文献
102.
A sensitive and selective flow injection method for the determination of phosphatidylcholine (PC) in sediment pore waters and extracts is described. It involves the use of phospholipase C, alkaline phosphatase and choline oxidase co-immobilized on controlled pore glass in a packed column reactor. The final product of the enzymatic reaction of phosphatidylcholine is hydrogen peroxide, and this is detected by measuring the chemiluminescence emission resulting from cobalt(II) catalysed reaction with luminol. The flow injection method is rapid (30 injections/h), reproducible (1.4% R.S.D. at 3 μM PC, n = 10) with a detection limit of 0.14 μM (estimated from 3σn−1 of the measured blank). A linear calibration response was obtained over a concentration range of 0.5-9 μM (r = 0.999). The method has been applied to the determination of phosphatidylcholine in sediment extracts and sediment pore waters. 相似文献
103.
The construction, performance characteristics and applications of a polymeric membrance electrode for lead(II) ion are reported.
The electrode was prepared by incorporating cryptand(222) as the neutral carrier into a plasticized poly(vinyl chloride) membrane.
The influence of membrane composition, pH and concentration of internal reference solution were investigated. The electrode
exhibits a potentiometric response for Pb2+ ion over the concentration range 10–1–10–5 M with a detection limit of 5 × 10–6 M Pb2+. It shows a relatively fast response time of about 30 s and can be used for about two months without any considerable divergence
in potential. The proposed sensor revealed good selectivities for Pb2+ in the presence of several metal ions and could be used in the pH range of 2.5 to 7.5. It was used as an indicator electrode
in the potentiometric titration of Pb2+ with EDTA.
Received: 20 November 1998 / Revised: 26 March 1999 / Accepted: 31 March 1999 相似文献
104.
Ghobadian Roshanak Esfandyari Roghaieh Nadri Hamid Moradi Alireza Mahdavi Mohammad Akbarzadeh Tahmineh Khaleghzadeh-Ahangar Hossein Edraki Najmeh Sharifzadeh Mohammad Amini Mohsen 《Molecular diversity》2020,24(1):211-223
Molecular Diversity - Inhibition of butyrylcholinesterase (BChE) might be a useful therapeutic target for Alzheimer’s disease (AD). A new series of 1,2,3,4-tetrahydro-9H-carbazole derivatives... 相似文献
105.
Amirreza Azadmeher Mostafa M. Amini Nasser Hadipour Hamid Reza Khavasi Hoong‐Kun Fun Chun‐Jung Chen 《应用有机金属化学》2008,22(1):19-24
Two new diorganotin(IV) derivatives of 2,6‐pyridinedicarboxylic acid, {[Ph2Sn(2,6‐C5H3N)(COO)2][Na(2,6‐C5H3N)(COOH) (COO)(CH3OH)2]} ( 1 ) and [Me2Sn(2,6‐C5H3N)(COO)2(H2O)]•H2O ( 2 ) were synthesized by the reaction of Ph3SnCl and PhMe2SnI with 2,6‐pyridinedicarboxylic acid, respectively in the presence of sodium methoxide or potassium iso‐propoxide. The prepared compounds were characterized by mass spectrometry, IR, 1H, 13C and 119Sn NMR spectroscopies. The molecular structures of both complexes were determined by a single‐crystal X‐ray analysis. The X‐ray structure revealed pentagonal bipyramidal geometry around the tin atom for compound 1, which is incorporated with a hexacoordinated monosodium derivative of 2,6‐pyridinedicarboxylic acid. Complex 2 adopts a monomeric structure with two carboxylate oxygen atoms coordinated to tin in monodenate form from equatorial positions, and the coordination number is raised to six as the oxygen of water and pyridine nitrogen occupies the other equatorial positions of octahedron. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
106.
The cesium 6(2)S(1/2) scalar dipole polarizability alpha(0) has been determined from the time-of-flight of laser cooled and launched cesium atoms traveling through an electric field. We find alpha(0)=6.611+/-0.009 x 10(-39) C m(2)/V=59.42+/-0.08 x 10(-24) cm(3)=401.0+/-0.6a(3)(0). The 0.14% uncertainty is a factor of 14 improvement over the previous measurement. Values for the 6(2)P(1/2) and 6(2)P(3/2) lifetimes and the 6(2)S(1/2) cesium-cesium dispersion coefficient C6 are determined from alpha(0) using the procedure of Derevianko and Porsev [Phys. Rev. A 65, 053403 (2002)]]. 相似文献
107.
Noninvasive estimation of tissue temperature via high-resolution spectral analysis techniques 总被引:8,自引:0,他引:8
We address the noninvasive temperature estimation from pulse-echo radio frequency signals from standard diagnostic ultrasound imaging equipment. In particular, we investigate the use of a high-resolution spectral estimation method for tracking frequency shifts at two or more harmonic frequencies associated with temperature change. The new approach, employing generalized second-order statistics, is shown to produce superior frequency shift estimates when compared to conventional high-resolution spectral estimation methods Seip and Ebbini (1995). Furthermore, temperature estimates from the new algorithm are compared with results from the more commonly used echo shift method described in Simon et al. (1998). 相似文献
108.
Automatic segmentation of thalamus from brain MRI integrating fuzzy clustering and dynamic contours 总被引:2,自引:0,他引:2
Amini L Soltanian-Zadeh H Lucas C Gity M 《IEEE transactions on bio-medical engineering》2004,51(5):800-811
Thalamus is an important neuro-anatomic structure in the brain. In this paper, an automated method is presented to segment thalamus from magnetic resonance images (MRI). The method is based on a discrete dynamic contour model that consists of vertices and edges connecting adjacent vertices. The model starts from an initial contour and deforms by external and internal forces. Internal forces are calculated from local geometry of the model and external forces are estimated from desired image features such as edges. However, thalamus has low contrast and discontinues edges on MRI, making external force estimation a challenge. The problem is solved using a new algorithm based on fuzzy C-means (FCM) unsupervised clustering, Prewitt edge-finding filter, and morphological operators. In addition, manual definition of the initial contour for the model makes the final segmentation operator-dependent. To eliminate this dependency, new methods are developed for generating the initial contour automatically. The proposed approaches are evaluated and validated by comparing automatic and radiologist's segmentation results and illustrating their agreement. 相似文献
109.
The aim of this paper is to present a hybrid approach to accurate quantification of vascular structures from magnetic resonance angiography (MRA) images using level set methods and deformable geometric models constructed with 3-D Delaunay triangulation. Multiple scale filtering based on the analysis of local intensity structure using the Hessian matrix is used to effectively enhance vessel structures with various diameters. The level set method is then applied to automatically segment vessels enhanced by the filtering with a speed function derived from enhanced MRA images. Since the goal of this paper is to obtain highly accurate vessel borders, suitable for use in fluid flow simulations, in a subsequent step, the vessel surface determined by the level set method is triangulated using 3-D Delaunay triangulation and the resulting surface is used as a parametric deformable model. Energy minimization is then performed within a variational setting with a first-order internal energy; the external energy is derived from 3-D image gradients. Using the proposed method, vessels are accurately segmented from MRA data. 相似文献
110.
Tag surface reconstruction and tracking of myocardial beads from SPAMM-MRI with parametric B-spline surfaces 总被引:1,自引:0,他引:1
Magnetic resonance imaging (MRI) is unique in its ability to noninvasively and selectively alter tissue magnetization, and create tag planes intersecting image slices. The resulting grid of signal voids allows for tracking deformations of tissues in otherwise homogeneous-signal myocardial regions. In this paper, we propose a specific spatial modulation of magnetization (SPAMM) imaging protocol together with efficient techniques for measurement of three-dimensional (3-D) motion of material points of the human heart (referred to as myocardial beads) from images collected with the SPAMM method. The techniques make use of tagged images in orthogonal views by explicitly reconstructing 3-D B-spline surface representation of tag planes (tag planes in two orthogonal orientations intersecting the short-axis (SA) image slices and tag planes in an orientation orthogonal to the short-axis tag planes intersecting long-axis (LA) image slices). The developed methods allow for viewing deformations of 3-D tag surfaces, spatial correspondence of long-axis and short-axis image slice and tag positions, as well as nonrigid movement of myocardial beads as a function of time. 相似文献