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101.
CZE coupled to sheath liquid-based electrospray ionization (ESI) and multiple-stage ion trap mass spectrometry (MS(n) ) was used for the confirmation analysis of ethyl glucuronide (EtG) and ethyl sulfate (EtS) in human serum and urine collected after intake of alcoholic beverages. Electrophoretic separations were performed in uncoated fused-silica capillaries using a pH 9.5 ammonium acetate background electrolyte and normal polarity. MS detection of EtG and EtS occurred after negative ionization using a spray liquid containing 0.5%?v/v ammonia in isopropanol/water (60:40%, v/v). CZE-MS and CZE-MS2 results obtained after injection of solid-phase extracts for EtG and EtS and of diluted urine confirmed the presence of EtG and EtS in samples whose levels were previously determined by CZE with indirect UV detection. Detection limits of each compound were estimated to be around 2.0 (injection of diluted urine) and 0.2?μg/mL (extracts). 相似文献
102.
Jitka Housková Michaela Hrdá Kamila Syslová Petr Novotný Petr Kačer 《Chromatographia》2011,73(1):131-135
An analytical method combining high-performance liquid chromatography (HPLC) with UV detection was developed for an easy and rapid assay determination of the anticancer drug picoplatin (=cis-[Pt(NH3)(2-methylpyridine)Cl2]) and its degradation products. An ion exchanger was used as the stationary phase with an aqueous solution of NaH2PO4 with pH adjusted to 3.0 with H3PO4 as the mobile phase. The calibration curve was linear within the concentration range of 0.10–0.50 g L?1 (R 2 ≥ 0.998). The limit of detection was 0.05 g L?1 and limit of quantification was 0.09 g L?1. The developed method was characterized with a high precision (≤6.0%, determined as RSD), an acceptable accuracy (the values of recovery were from intervals 98–103%). The developed method was used for assessing the stability of picoplatin during a stability study. 相似文献
103.
Lenka Husáková Iva Urbanová Lenka Audrlická-Vavrušová Jitka Šrámková Tomáš Černohorský Marie Bednaříková Lucie Pilařová 《Mikrochimica acta》2011,173(1-2):173-181
This work shows the analytical potential of inductively coupled plasma orthogonal-acceleration time-of-flight mass spectrometry (ICP-OA-TOF-MS) for rapid, simultaneous, and reliable determination of more than 50 elements at ultra-trace levels in urine. Under optimum instrumental conditions, after a 10-fold sample dilution step, and by using Rh as an internal standard, ICP-OA-TOF-MS also enables the determination of elements whose assay is more diffcult when using conventional quadrupole instruments. This is confirmed by the analysis of commercially available reference urine samples and/or by analytical recoveries study and isotope ratio based determination of accuracies. On the other side, the interference resulting from polyatomic carbon, chlorine, or various sulfur species does not allow the determination of elements such as Cr, Fe, V, Se and As without a mathematical correction. Figure
Part of the ICP-TOF-MS mass spectra recorded from SeronormTM Trace Elements Urine Lot 0511545 diluted in 1+9 ratio with water 相似文献
104.
High‐resolution capillary zone electrophoresis is used to distinguish transferrin glycoforms present in human serum, cerebrospinal fluid, and serum treated with neuraminidase and N‐glycosidase F. The obtained data are compared to mass spectrometry data from the literature. The main focus is on the analysis of the various asialo‐transferrin, monosialo‐transferrin, and disialo‐transferrin molecules found in these samples. The features of capillary zone electrophoresis and mass spectrometry are reviewed and highlighted in the context of the analysis of undersialylated and hypoglycosylated transferrin molecules. High‐resolution capillary zone electrophoresis represents an effective tool to assess the diversity of transferrin patterns whereas mass spectrometry is the method of choice to elucidate structural identification about the glycoforms. Hypoglycosylated transferrin glycoforms present in sera of alcohol abusers and normal subjects are structurally identical to those in sera of patients with a congenital disorder of glycosylation type I. Asialo‐transferrin, monosialo‐transferrin and disialo‐transferrin observed in sera of patients with a type II congenital disorder of glycosylation or a hemolytic uremic syndrome, in cerebrospinal fluid and after treatment of serum with neuraminidase are undersialylated transferrin glycoforms with two N‐glycans of varying structure. Undersialylated disialo‐transferrin is also observed in sera with high levels of trisialo‐transferrin. 相似文献
105.
Martina Zatloukalová Teodor Adrian Enache Vladimír Křen Jitka Ulrichová Jan Vacek Ana Maria Oliveira‐Brett 《Electroanalysis》2013,25(7):1621-1627
The galloyl substitution effect on the antioxidant potential of quercetin‐3‐O‐gallate (QG) and silybin‐3‐O‐gallate (SBG), and the oxidation of QG and SBG were studied by cyclic, differential and square‐wave voltammetry using a glassy carbon electrode, and compared with their structural components, quercetin (Q), silybin (SB), gallic acid and gallic acid methyl ester. Their multi‐step pH‐dependent anodic behaviour, first oxidation followed by oxidation of the hydroxyl groups at ring A, is similar to Q and SB. The galloyl substitution significantly improved the antioxidant potential of SB compared to Q, and brought useful knowledge about the antioxidant activity of Q and SB monogalloyl esters. 相似文献
106.
Jitka Poměnková 《Applications of Mathematics》2008,53(4):305-317
Kernel smoothers belong to the most popular nonparametric functional estimates used for describing data structure. They can
be applied to the fix design regression model as well as to the random design regression model. The main idea of this paper
is to present a construction of the optimum kernel and optimum boundary kernel by means of the Gegenbauer and Legendre polynomials.
This work is part of the research project “The Czech Economy in the Process of Integration and Globalization, and the Development
of Agricultural Sector and the Sector of Service under the New Conditions of the Integrated European Market”. 相似文献
107.
Jitka Moravcova Petr KocalkaAnne Imberty David SykoraMiroslav Fris 《Tetrahedron letters》2003,44(49):8797-8800
Treatment of methyl 2,3-di-O-benzyl-4,6-O-benzylidene-α(β)-d-glucopyranoside with triethyl phosphite and trimethylsilyl trifluoromethanesulfonate affords the seven-membered phostone arising from the attack of reagents on the acetal protecting group. 相似文献
108.
Fluorescence of sanguinarine: fundamental characteristics and analysis of interconversion between various forms 总被引:2,自引:0,他引:2
Marika Janovská Martin Kubala Vilím ?imánek Jitka Ulrichová 《Analytical and bioanalytical chemistry》2009,395(1):235-240
The quaternary isoquinoline alkaloid, sanguinarine (SG) plays an important role in both traditional and modern medicine, exhibiting
a wide range of biological activities. Under physiological conditions, there is an equilibrium between the quaternary cation
(SG+) and a pseudobase (SGOH) forms of SG. In the gastrointestinal tract, SG is converted to dihydrosanguinarine (DHSG). All forms
exhibit bright fluorescence. However, their spectra overlap, which limited the use of powerful techniques based on fluorescence
spectroscopy/microscopy. Our experiments using a combination of steady-state and time-resolved techniques enabled the separation
of individual components. The results revealed that (a) the equilibrium constant between SG+ and SGOH is pK
a = 8.06, while fluorescence of DHSG exhibited no changes in the pH range 5–12, (b) the SGOH has excitation/emission spectra
with maxima at 327/418 nm and excited-state lifetime 3.2 ns, the spectra of the SG+ have maxima at 475/590 nm and excited-state lifetime 2.4 ns. The DHSG spectra have maxima at 327/446 nm and 2-exponential
decay with components 4.2 and 2.0 ns, (c) NADH is able to convert SG to DHSG, while there is no apparent interaction between
NADH and DHSG. These techniques are applicable for monitoring the SG to DHSG conversion in hepatocytes. 相似文献
109.
To solve a decision problem under uncertainty via stochastic programming means to choose or to build a suitable stochastic
programming model taking into account the nature of the real-life problem, character of input data, availability of software
and computer technology. In applications of multistage stochastic programs additional rather complicated modeling issues come
to the fore. They concern the choice of the horizon, stages, methods for generating scenario trees, etc. We shall discuss
briefly the ways of selecting horizon and stages in financial applications. In our numerical studies, we focus on alternative
choices of stages and their impact on optimal first-stage solutions of bond portfolio optimization problems.
AMS Subject classification 90C15 . 92B28 相似文献
110.
Marida Bertocchi Vittorio Moriggia Jitka Dupačová 《Annals of Operations Research》2000,99(1-4):267-286
The bond portfolio management problem is formulated as a stochastic program based on interest rate scenarios. The coefficients of the resulting program are subject to errors of various kind. In this paper, we complement the theoretical stability results of by simulation experiments. Adapting the approach of to problems based on perturbed yield curves, we then provide bounds for the optimality gap for various candidate first-stage solutions. 相似文献