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101.
102.
《中国化学快报》2020,31(9):2423-2427
Direct infusion mass spectrometry (DIMS) is a powerful technique in clinical diagnosis for screening neonatal amino acid metabolic disorders from dried blood spots (DBS). However, DIMS sometimes generated false-positive results for analysis of amino acids. In this work, we utilized a stable isotope derivatization method, combining with liquid chromatography tandem mass spectrometry (SID-LC-MS), to improve the specificity for screening amino acids in DBS specimens. A pair of isotope reagents, p-(dimethylamino)phenyl isothiocyanate (DMAP-NCS) and 4-isothiocyanato-N,N-bis(methyl-[2H2])aniline ([2H4]DMAP-NCS), was synthesized and used to label amino acids in DBS specimens. The [2H4]DMAP-NCS labelled amino acid standards were used as internal standards to compensate the matrix effect. This method was validated by measuring linearity, recovery and accuracy. The results showed that the developed SID-LC-MS method can be used for sensitive and selective determination of 12 diagnostically important amino acids in DBS specimens. 相似文献
103.
Clavijo CF Thomas JJ Cromie M Schniedewind B Hoffman KL Christians U Galinkin JL 《Journal of separation science》2011,34(24):3568-3577
Preterm and term neonates often require surgical procedures and analgesia. However, our knowledge about neonatal pharmacokinetics of fentanyl, the most commonly used drug for these procedures, and its metabolites is still incomplete. To facilitate pharmacokinetic studies of fentanyl and its metabolites in neonates and other children, we developed and validated an LC-MS/MS method based on minimally invasive, low blood volume sampling. LC-MS/MS was used for the simultaneous analysis of fentanyl, despropionyl fentanyl (DPF), and norfentanyl from dried blood samples (DBS) collected on filter paper. Positive ions were monitored using multiple reaction monitoring. Since the standard matrix for measuring fentanyl blood concentrations is plasma, the assay was developed and validated in plasma, whole blood, and then DBS. Our method was able to measure clinically relevant levels of fentanyl and its metabolites. In DBS, the lower limits of quantification were 100 pg/mL for fentanyl with a range of reliable response from 0.1 to 100 ng/mL (r(2)>0.99) and 250 pg/mL for both DPF and norfentanyl with a range of reliable response from 0.25 to 100 ng/mL (r(2)>0.99). In plasma and in DBS inter-day accuracy and precisions of fentanyl met predefined acceptance criteria and also indicated comparable assay performance in both matrices. 相似文献
104.
Anthony A. Provatas Steven L. Kolakowski Francis H. Sternberg James D. Stuart Christopher R. Perkins 《Analytical letters》2019,52(9):1379-1395
Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCs) are anthropogenic pollutants highly resistant to chemical degradation and readily absorbed by organic tissue. Their persistence in the environment and toxicological threat to mammals prompts swift, reliable methods of analysis. This study outlines a rapid, efficient and sensitive, validated methodology utilizing a simple liquid extraction technique, and subsequent analysis by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) for the determination of PCBs and OCs from dried blood spots. The PCBs and OCs were quantified in whole marine mammal blood spotted on Whatman Protein Saver cards (PSCs) by extracting the analytes into acetonitrile acidified with formic acid, followed by GC-MS/MS analysis. The samples were analyzed in positive electron impact (EI+) ionization mode with the electron energy set to 40?eV to preserve analyte integrity. Fortified blood with the analytes of interest was used for method validation and subsequent sample screening. The recoveries of targeted analytes ranged from 62.5% to 107.8%, with relative standard deviations ranging from 0.09% to 4.6% at a 100?ng·mL?1 concentration level. The method detection limits were from 40.4?ng·g?1 to 179.2?ng·g?1 for the PCBs and 37.6?ng·g?1 to 145.1?ng·g?1 for the OCs. The use of dried blood spots provided for numerous advantages compared to whole blood samples while demonstrating reduced matrix effects and enhanced sample lifespan while retaining analyte sensitivity. 相似文献
105.
Radoslaw Kwapiszewski Karina Kwapiszewska Jörg P. Kutter Zbigniew Brzozka 《Analytica chimica acta》2015
Lysosomal storage diseases are chronic, progressive and typically have a devastating impact on the patient and the family. The diagnosis of these diseases is still a challenge, however, even for trained specialists. Accurate diagnostic methods and high-throughput tools that could be readily incorporated into existing screening laboratories are urgently required. 相似文献
106.
Kazuhiro Ishige 《Journal of Differential Equations》2005,212(2):394-431
We consider the Cauchy-Neumann problem of the heat equation in the exterior domain of a ball in RN, and study the movement of hot spots of the solution as t→∞. 相似文献
107.
We report a simple algorithm to scan interfaces in protein–protein complexes for identifying binding ‘hot spots’. The change
in side-chain solvent accessible area (ΔASA) of interface residues has been related to change in binding energy due to mutating
interface residues to Ala (ΔΔG
X → ALA) based on two criteria—hydrogen bonding across the interface and location in the interface core—both of which are major determinants
in specific, high-affinity binding. These relationships are used to predict the energetic contribution of individual interface
residues. The predictions are tested against 462 experimental X → ALA mutations from 28 interfaces with an average unsigned
error of 1.04 kcal/mol. More than 80% of interface hot spots (with experimental ΔΔG ≥ 2 kcal/mol) could be identified as being energetically important. From the experimental values, Asp, Lys, Tyr and Trp are
found to contribute most of the binding energy, burying >45 Å2 on average. The method described here would be useful to understand and interfere with protein interactions by assessing
the energetic importance of individual interface residues.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
108.
Gu Xu Materials Science Engineering McMaster University Hamilton Ontario LS L Canada 《高分子科学》2003,(5):527-531
Organic Light Emitting Devices (OLED) have attracted much attention recently, for their applications in futureFlat Panel Displays and lighting products. However, their fast degradation remained a major obstacle to theircommercialization. Here we present a brief summary of our studies on both extrinsic and intrinsic causes for the fastdegradation of OLEDs. In particular, we focus on the origin of the dark spots by "rebuilding" cathodes, which confirms thatthe growth of dark spots occurs primarily due to cathode delamination. In the meantime, we recapture the findings from thesearch for suitable OLED packaging materials, in particular polymer composites, which provide both heat dissipation andmoisture resistance, in addition to electrical insulation. 相似文献
109.
R. Nageswara Rao Sravan Bompelli Pawan K. Maurya 《Biomedical chromatography : BMC》2011,25(11):1252-1259
A selective and sensitive high‐performance liquid chromatography method with fluorescence detection for simultaneous determination of irbesartan, losartan and valsartan on dried blood spots (DBS) has been developed and validated. It involves solvent extraction of a punch of DBS followed by reversed‐phase liquid chromatography on a Lichrospher® 100 RP‐18e column. Fluorescence detection was performed at 259 and 385 nm as excitation and emission wavelengths, respectively. The detection limits of irbesartan, losartan and valsartan were 1.8, 3.6 and 1.8 ng/mL respectively. The mean recoveries of irbesartan, losartan and valsartan were 98.68, 98.42 and 97.81%, respectively. The mean inter‐day and intra‐day precisions of irbesartan, losartan and valsartan were 2.07 and 1.34%, 1.42 and 1.48%, and 3.20 and 2.15% respectively. The proposed method was simple and rapid. Design of experiments was used to evaluate the robustness of the method. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
110.
Ultrasonic irradiation of solutions containing volatile organometallic complexes results in intense emission from excited-state metal atoms. We have determined the effect of dissolved gases (Xe, Kr, Ar, Ne, He, CF4, C2F6, CO, N2) on the intensity of the sonoluminescence resulting from ultrasonic irradiation of silicone oil solutions of Cr(CO)6. This provides a well-defined, spectrally resolved probe of sonoluminescence with emission resulting from a single species, the chromium atom excited states. As predicted by the hot-spot, thermal mechanisms of sonoluminescence, the intensity of excited-state Cr emission decreases with increasing thermal conductivity of the noble gases. The intensity of sonoluminescence increases with increasing γ (i.e. Cp/Cv), which is also in accord with a thermal mechanism. Sonoluminescence is substantially diminished by the addition of even small amounts (≈ 1%) of CF4 or C2F6, even though they are capable of supporting electrical discharge. This is in agreement with a thermal mechanism, but is in direct conflict with electrical theories of sonoluminescence. 相似文献