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排序方式： 共有771条查询结果，搜索用时 15 毫秒
91.
92.
Annali di Matematica Pura ed Applicata (1923 -) - 相似文献
93.
Laura Leoni;Federica Rosmini;Francesca Ledda;Mirko Parasiliti-Caprino;Fabio Settanni;Antonello Nonnato;Ezio Ghigo;Paolo Moghetti;Giulio Mengozzi;Federico Ponzetto; 《Biomedical chromatography : BMC》2024,38(10):e5982
Biochemical confirmation of ovulation typically involves measuring serum progesterone levels during the mid-luteal phase. Alternatively, this information could be obtained by monitoring urinary excretion of conjugated metabolites of ovarian steroids such as pregnanediol 3-glucuronide (PDG) using immunoassay techniques that have methodological limitations. The aim of the present study was to develop a mass spectrometry (MS)-based method for the rapid and accurate measurement of urinary PDG levels in spot urine samples. A “dilute and shoot” ultra-high-performance liquid cromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed for measuring PDG urinary concentration with a 6-min analysis time. The method underwent validation in accordance with ISO 17025 documentation for quantitative methods, proving an efficient separation of PDG from other structurally similar glucuro-conjugated steroid metabolites and ensuring a sufficient sensitivity for detecting the target analyte at concentrations as low as 0.01 μg/mL. The validation protocol yielded satisfactory results in terms of accuracy, repeatability, intermediate precision, and combined uncertainty. Additionally, the stability of both the samples and calibration curves was also conducted. The application to real urine samples confirmed the method's capability to measure PDG levels throughout an entire menstrual cycle and detecting ovulation. The rapidity of the analytical platform would therefore enable high throughput analysis, which is advantageous for large cohort clinical studies. 相似文献
94.
Ahmad Bachir Fabiana Ciocchetti Daniel P. Couto Dr. Simone Di Noja Dr. Cristian Pezzato Dr. Giulio Ragazzon 《European journal of organic chemistry》2023,26(29):e202300498
Cyclobis(paraquat-p-phenylene), also known as “blue box”, is a highly electron-deficient macrocycle, widely used as a molecular receptor for small electron-rich molecules. Inserting a reactive functional group onto the molecular structure of this cyclophane is paramount for its inclusion into complex architectures. To this aim, including an alkyne moiety would be ideal, because it can participate in click reactions. However, the synthesis of such alkyne-functionalized cyclophane suffers from several drawbacks: the use of toxic and expensive CCl4, the need for high-pressure reactors, and overall low yield. We have revised the existing synthesis of this cyclophane derivative bearing an alkyne moiety, to overcome all these limitations. In particular, photochemical radical bromination is adopted to obtain a sensitive intermediate. We demonstrated that the synthesized host molecule can be functionalized via click reactions and take part in radical-radical interactions. Our work makes a key functionalized paraquat macrocycle more accessible, facilitating the development of novel redox-responsive systems. 相似文献
95.
Andrea Sabatino Emanuele Penocchio Giulio Ragazzon Alberto Credi Diego Frezzato 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14479-14486
The first study in which stochastic simulations of a two‐component molecular machine are performed in the mass‐action regime is presented. This system is an autonomous molecular pump consisting of a photoactive axle that creates a directed flow of rings through it by exploiting light energy away from equilibrium. The investigation demonstrates that the pump can operate in two regimes, both experimentally accessible, in which light‐driven steps can be rate‐determining or not. The number of photons exploited by an individual molecular pump, as well as the precision of cycling and the overall efficiency, critically rely on the operating regime of the machine. This approach provides useful information not only to guide the chemical design of a self‐assembling molecular device with desired features, but also to elucidate the effect of the environment on its performance, thus facilitating its experimental investigation. 相似文献
96.
A methodology based on the theory of optimal transport is developed to attribute variability in data sets to known and unknown factors and to remove such attributable components of the variability from the data. Denoting by x the quantities of interest and by z the explanatory factors, the procedure transforms x into filtered variables y through a z‐dependent map, so that the conditional probability distributions ρ(x|z) are pushed forward into a target distribution μ(y), independent of z. Among all maps and target distributions that achieve this goal, the procedure selects the one that minimally distorts the original data: the barycenter of the ρ(x|z). Connections are found to unsupervised learning and to fundamental problems in statistics such as conditional density estimation and sampling. Particularly simple instances of the methodology are shown to be equivalent to k‐means and principal component analysis. An application is shown to a time series of ground temperature hourly data across the United States.© 2017 Wiley Periodicals, Inc. 相似文献
97.
Pierluigi Perrone Silvello Betti Giuseppe Giulio Rutigliano 《Fiber and Integrated Optics》2017,36(4-5):181-195
This article proposes a novel coherent multilevel modulation model that exploits polarization and phase of the field. This model is based on the possibility of coherent systems to use all the four degrees of freedom of the electromagnetic field. The proposed scheme is able, by applying a suitable twisting process to the optical fiber, to physically confine the polarization and the phase of the transmitted field within the phase sphere. In this way, with the same performances of existing systems, the receiver is considerably simplified because there is no longer need of birefringence tracking circuits. 相似文献
98.
Alejandro De la Cadena Carlo M. Valensise Marco Marangoni Giulio Cerullo Dario Polli 《Journal of Raman spectroscopy : JRS》2020,51(10):1951-1959
We introduce a high-sensitivity broadband stimulated Raman scattering (SRS) setup featuring wide spectral coverage (up to 500 cm−1) and high-frequency resolution (≈20 cm−1). The system combines a narrowband Stokes pulse, obtained by spectral filtering an Yb laser, with a broadband pump pulse generated by a home-built optical parametric oscillator. A single-channel lock-in amplifier connected to a single-pixel photodiode measures the stimulated Raman loss signal, whose spectrum is scanned rapidly using a galvanometric mirror after the sample. We use the in-line balanced detection approach to suppress laser fluctuations and achieve close to shot-noise-limited sensitivity. The setup is capable of measuring accurately the SRS spectra of several solvents and of obtaining hyperspectral data cubes consisting in the broadband SRS microscopy images of polymer beads test samples as well as of the distribution of different biological substances within plant cell walls. 相似文献
99.
Giulio Simone Daniel Tordera Ezequiel Delvitto Bart Peeters Albert J. J. M. van Breemen Stefan C. J. Meskers Ren A. J. Janssen Gerwin H. Gelinck 《Advanced Optical Materials》2020,8(10)
Reflectance oximeters based on organic photodiode (OPD) arrays offer the potential to map blood pulsation and oxygenation via photoplethysmography (PPG) over a large area and beyond the traditional sensing locations. Here, an organic reflectance PPG array based on 16 × 16 OPD pixels is developed. The individual pixels exhibit near‐infrared sensitivity up to ≈950 nm and low dark current density in the order of 10−6 mA cm−2. This results in high‐quality PPG signals. Analysis of the full PPG waveform yields insight on the artery stiffness and the quality of blood circulation, demonstrating the potential of these arrays beyond pulse oximetry and heart‐rate calculation. 相似文献
100.
We consider a general class of disordered mean-field models where both the spin variables and disorder variables η take finitely many values. To investigate the size-dependence in the phase-transition regime we construct the metastate describing the probabilities to find a large system close to a particular convex combination of the pure infinite-volume states. We show that, under a non-degeneracy assumption, only pure states j are seen, with non-random probability weights w j for which we derive explicit expressions in terms of interactions and distributions of the disorder variables. We provide a geometric construction distinguishing invisible states (having w j =0) from visible ones. As a further consequence we show that, in the case where precisely two pure states are available, these must necessarily occur with the same weight, even if the model has no obvious symmetry relating the two. 相似文献