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排序方式: 共有139条查询结果,搜索用时 15 毫秒
1.
V. Sree Krishna Chaitanya 《Nonlinear Analysis: Real World Applications》2005,6(5):845-857
In this paper, a structurally unstable man–machine system is considered and a rigorous mathematical analysis is performed to study the influence of time delays in the control force on stability of the equilibrium solution of this system. Results on stability, instability and conditions for the preservation of stability (instability), besides the existence of bifurcation are presented. 相似文献
2.
Saxena C Wang H Kavakli IH Sancar A Zhong D 《Journal of the American Chemical Society》2005,127(22):7984-7985
In this communication, we report the ultrafast dynamics of resonance energy transfer in a blue-light photoreceptor, Vibrio cholerae cryptochrome. The transfer was observed to occur in 60 ps. We also studied the local rigidity and solvation around the binding site of the photoantenna molecule. The results for the first time show energy transfer in cryptochrome suggesting some mechanistic similarities between photolyase that repairs damaged DNA and cryptochrome that mediates blue-light signaling. 相似文献
3.
Urmila H. Patel Chaitanya G. Dave Mukesh M. Jotani Hetal C. Shah 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o191-o192
The crystal structure of the title compound, C20H18N2O, reveals a distorted half‐chair conformation of the central tetrahydropyridine (THP) ring, with the cyano‐ and adjacent phenyl‐substituted C atoms displaced by 0.329 (1) and ?0.315 (1) Å, respectively, from the THP best plane. Steric interactions force the phenyl rings out of the THP plane by 49.21 (9) and 65.76 (5)°. The cyano moiety is coplanar with the THP plane. 相似文献
4.
Urmila H. Patel Chaitanya G. Dave Mukesh M. Jotani Hetal C. Shah 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):o697-o699
The title compound, C20H16N2O, has two molecules in the asymmetric unit and the crystal structure shows that the central pyridine ring of each molecule has a flat boat conformation. The terminal C atom in one of the molecules is disordered over two positions, with relative occupancies of 0.594 (14) and 0.398 (14). Intermolecular C—H?N and C—H?π interactions and π–π stacking, along with intramolecular C—H?N and C—H?π interactions, help to stabilize the structure. 相似文献
5.
A number of 2-thioxopyrido[3′,2′:4,5]thieno[3,2-H]pyrimdin-4(3H-ones (5) have been synthesized by cyclocondensation of 2-carbethoxy-3-amino-4-phenyl-6-substituted-thieno[2,3-b]pyridines (3) with various isothiocyanates. Compounds 5 were S-methylated routinely and the reactions compared under solid-liquid phase transfer conditions to obtain 2-methylthiopyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-ones (6). The new triheterocyclic pyridothienopyrimidines were prepared with the objective to study their pharmacological properties. 相似文献
6.
Rate constants of the reactions of O(3P) atoms with Br2 and NO2 over the temperature range 220-950 K
The kinetics of the reactions of Br2 and NO2 with ground state oxygen atoms have been studied over a wide temperature range, T = 220-950 K, using a low-pressure flow tube reactor coupled with a quadrupole mass spectrometer: O + NO2 → NO + O2 (1) and O + Br2 → Br + BrO (2). The rate constant of reaction (1) was determined under pseudo–first-order conditions, either monitoring the kinetics of O-atom or NO2 consumption in excess of NO2 or of the oxygen atoms, respectively: k1 = (6.1 ± 0.4) × 10−12 exp((155 ± 18)/T) cm3 molecule−1 s−1 (where the uncertainties represent precision at the 2σ level, the estimated total uncertainty on k1 being 15% at all temperatures). The temperature dependence of k1, found to be in excellent agreement with multiple previous low-temperature data, was extended to 950 K. The rate constant of reaction (2) determined under pseudo–first-order conditions, monitoring the kinetics of Br2 consumption in excess of O-atoms, showed upward curvature at low and high temperatures of the study and was fitted with the following three-parameter expression: k2 = 9.85 × 10−16 T1.41 exp(543/T) cm3 molecule−1 s−1 at T = (220-950) K, which is recommended from the present study with an independent of temperature conservative uncertainty of 15% on k2. 相似文献
7.
Research on Chemical Intermediates - In industries where a heat exchanger is made up of Cu–Ni (90/10) alloy and seawater is used as a coolant, microbially influenced corrosion (MIC) is a... 相似文献
8.
Dr. Rakesh Chilivery Dr. Gousia Begum Vahinipathi Chaitanya Dr. Rohit Kumar Rana 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(21):8237-8242
A bio-inspired method is used to render controlled wrinkling surface patterns on supramolecular architectures assembled from polyoxometalate (POM) clusters. It involves a polyamine-multivalent anion interaction generating positively charged coacervates, which while dictating the assembly of POM into spherical structures further facilitate an interesting surface morphogenesis with wrinkling patterns. This spontaneous surface wrinkling depends on the type of multivalent anion and the pH. As the polyamine-anion interaction becomes stronger, the wrinkles turn denser with lesser depth, which eventually undergoes post-buckling to engender a complex surface pattern. Interestingly, the order of influence exerted by different anions on the morphology follows the Hofmeister series. Moreover, the mild synthesis conditions keep the functional POM units dispersed in the sphere with a structural transformability to their lacunary form. 相似文献
9.
Rupam Sarma Pradip Chowdhury Chaitanya Bikkina Sasidhar Gumma Jubaraj B. Baruah 《Journal of chemical crystallography》2010,40(10):892-896
Abstract
The structural aspects of one-dimensional coordination polymer (1) of nickel(II) with 1,3,5-benzene tricarboxylate and a three-dimensional interpenetrating coordination polymer (2) of zinc(II) with 1,4-benzenedicarboxylate ligand are studied by single crystal X-ray diffraction analysis. Coordination polymer (1) forms a hydrogen bonded three dimensional network structures. The coordination polymer 1 having a composition [Ni3(TMA)2(H2O)12] n where (TMA = trimesate anion), crystallizes in monoclinic crystal system with C2 space group and has a/?, 17.3387(4); b/?, 12.8748(4); c/?, 6.5302(2); β/°111.620(2); V/?3, 1355.20(7). The zinc coordination polymer 2 crystal system is orthorhombic, with space group Pbca. It has a/?, 14.5049(3); b/?, 17.1616(3); c/?, 18.1389(4); V/?3, 4515.27(16). The 1,4-benzenedicarboxylate three dimensional coordination polymer of zinc(II) comprises of novel hydroxo bridged tetranuclear zinc(II) secondary building units and has a composition [Zn2(C6H4C2O4)1.5{(CH3)2SO}2(OH)] n . Topological analysis of the three dimensional coordination polymer 2 shows that it has a two fold interpenetrating net topology. 相似文献10.
Dongre C Dekker R Hoekstra HJ Pollnau M Martinez-Vazquez R Osellame R Cerullo G Ramponi R van Weeghel R Besselink GA van den Vlekkert HH 《Optics letters》2008,33(21):2503-2505
Using femtosecond laser writing, optical waveguides were monolithically integrated into a commercial microfluidic lab-on-a-chip device, with the waveguides intersecting a microfluidic channel. Continuous-wave laser excitation through these optical waveguides confines the excitation window to a width of 12 microm, enabling high-resolution monitoring of the passage of different types of fluorescent analytes when migrating and being separated in the microfluidic channel by microchip capillary electrophoresis. Furthermore, we demonstrate on-chip-integrated waveguide excitation and detection of a biologically relevant species, fluorescently labeled DNA molecules, during microchip capillary electrophoresis. Well-controlled plug formation as required for on-chip integrated capillary electrophoresis separation of DNA molecules, and the combination of waveguide excitation and a low limit of detection, will enable monitoring of extremely small quantities with high spatial resolution. 相似文献