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161.
Background
Although hair testing is well established for the assessment of past drug exposure, uncertainties persist about mechanisms of drug incorporation into hair and interpretation of results. The aim of this study was to administer methamphetamine (MAMP) under controlled conditions as a model drug to investigate drug incorporation into human hair.Material and methods
Seven volunteers with a history of stimulant use received 4 × 10 mg (low) doses of sustained release S-(+)-MAMP HCl within 1 week, with weekly head hair samples collected by shaving. 3 weeks later, 4 of them received 4 × 20 mg (high) doses. After extensive isopropanol/phosphate buffer washing of the hair, MAMP and its metabolite amphetamine (AMP) concentrations were determined in all weekly hair samples by LC–MS–MS in selected reaction monitoring mode with the undeca- and deca-deuterated drugs, respectively, as internal standards (LLOQ, 0.005 ng mg−1).Results
MAMP Tmax occurred from 1 to 2 weeks after both doses, with Cmax ranging from 0.6 to 3.5 ng mg−1 after the low and 1.2 to 5.3 ng mg−1 after the high MAMP doses. AMP Cmax in hair was 0.1–0.3 ng mg−1 and 0.2–0.5 ng mg−1, respectively, for low and high doses. Highly dose-related concentrations within subjects, but large variability between subjects were observed. MAMP concentrations were above the 0.2 ng mg−1 cut-off for at least 2 weeks following administration of both low and high doses. The overall AMP/MAMP ratio ranged from 0.07 to 0.37 with a mean value of 0.15 ± 0.07, and a median of 0.13. The percentage of MAMP and AMP removed with the washing procedure decreased with time after administration. A strong correlation was found between area under the curve of MAMP (r2 = 0.90, p = 0.00) and AMP (r2 = 0.94, p = 0.00) concentrations calculated for the 3-week period following administration and the total melanin concentration in hair. Significant correlations were observed also between Cmax and melanin.Conclusions
This study demonstrated that despite large inter-individual differences, the incorporation of MAMP and AMP into hair is dose-related with much of the observed scatter of MAMP and AMP concentrations explained by melanin concentration in hair. 相似文献162.
Mara Mirasoli Angela Buragina Luisa Stella Dolci Massimo Guardigli Patrizia Simoni Angel Montoya Elisabetta Maiolini Stefano Girotti Aldo Roda 《Analytica chimica acta》2012
Simple, rapid and highly sensitive assays, possibly allowing on-site analysis, are required in the security and forensic fields or to obtain early signs of environmental pollution. Several bioanalytical methods and biosensors based on portable devices have been developed for this purpose. Among them, Lateral Flow ImmunoAssays (LFIAs) offer the advantages of rapidity and ease of use and, thanks to the high specificity of antigen–antibody binding, allow greatly simplifying and reducing sample pre-analytical treatments. However, LFIAs usually employ colloidal gold or latex beads as labels and they rely on the formation of colored bands visible by the naked eye. With this assay format, only qualitative or semi-quantitative information can be obtained and low sensitivity is achieved. Recently, the use of enzyme-catalyzed chemiluminescence detection in LFIA has been proposed to overcome these problems. In this work, we describe the development of a quantitative CL-LFIA assay for the detection of 2,4,6-trinitrotoluene (TNT) in real samples. Thanks to the use of a portable imaging device for CL signal measurement based on a thermoelectrically cooled CCD camera, the analysis could be performed directly on-field. A limit of detection of 0.2 μg mL−1 TNT was obtained, which is five times lower than that obtained with a previously described colloidal gold-based LFIA developed employing the same immunoreagents. The dynamic range of the assay extended up to 5 μg mL−1 TNT and recoveries ranging from 97% to 111% were obtained in the analysis of real samples (post blast residues obtained from controlled explosion). 相似文献
163.
Carlo Scapolla Giuliana Cangemi Sebastiano Barco Laura Barbagallo Daniela Bugnone Angelo Maffia Giovanni Melioli Aldo Profumo Umberto Benatti Gianluca Damonte 《Journal of mass spectrometry : JMS》2012,47(7):816-824
The levels of urinary catecholamine metabolites, such as homovanillic acid (HVA) and vanillylmandelic acid, are routinely used as a clinical tool in the diagnosis and follow‐up of neuroblastoma (NB) patients. Recently, in the Clinical Pathology Laboratory Unit of G. Gaslini Children Hospital, a commercial method that employs liquid chromatography coupled to electrochemical detection (LC‐EC) has been introduced for the measurement of these metabolites in the routine laboratory practice. Using this LC‐EC method, an unknown peak could be observed only in samples derived from NB patients. To investigate the nature of this peak, we used a combination of liquid chromatography‐time‐of‐flight mass spectrometry (LC‐TOF‐MS) and liquid chromatography‐ion trap tandem mass spectrometry (LC‐IT‐MS). The first approach was used to obtain the elemental composition of the ions present in this new signal. To get additional structural information useful for the elucidation of unknown compounds, the ion trap analyzer was exploited. We were able to identify not just one, but three unknown signals in urine samples from NB patients which corresponded to three conjugated products of HVA: HVA sulfate and two glucuronoconjugate isomers. The enzymatic hydrolysis with β‐glucuronidase confirmed the proposed structures, while the selective alkaline hydrolysis allowed us to distinguish the difference between phenol‐ and acyl‐glucuronide of HVA. The latter was the unknown peak observed in LC‐EC separations of urine samples from NB patients. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
164.
Rampino S Faginas Lago N Laganà A Huarte-Larrañaga F 《Journal of computational chemistry》2012,33(6):708-714
Within the activities of the D37 COST Action, we have further developed the quantum dynamics framework of the grid empowered molecular simulator (GEMS) implemented on the segment of the European grid available to the COMPCHEM (computational chemistry) virtual organization. GEMS does now include in a full ab initio approach, the evaluation of the detailed quantum (both time dependent and time independent) dynamics of small systems starting from the calculation of the electronic structure properties as well as the direct calculation of thermalized properties. Illustrative, full dimensional applications of the extended simulator to the H + H(2) , N + N(2) , and O + O(2) systems are presented. 相似文献
165.
In this work we review two classical isoperimetric inequalities involving eigenvalues of the Laplacian, both with Dirichlet
and Neumann boundary conditions. The first one is classically attributed to Krahn and P. Szego and asserts that among sets
of given measure, the disjoint union of two balls with the same radius minimizes the second eigenvalue of the Dirichlet–Laplacian,
while the second one is due to G. Szegő and Weinberger and deals with the maximization of the first non-trivial eigenvalue
of the Neumann–Laplacian. New stability estimates are provided for both of them. 相似文献
166.
167.
Host–Guest Chemistry of a Bis‐Calix[4]pyrrole Derivative Containing a trans/cis‐Switchable Azobenzene Unit with Several Aliphatic Bis‐Carboxylates 下载免费PDF全文
Grazia Cafeo Franz H. Kohnke Giovanni Mezzatesta Aldo Profumo Camillo Rosano Antonino Villari Andrew J. P. White 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5323-5327
The azobenzene unit used as a photochemically and thermally switchable linker in the assembly of a bis‐calix[4]pyrrole receptor provides a means to modulate the binding of bis‐carboxylates of significant biological importance in cancer research. Conversely, the complexation of different bis‐anionic guests has significant kinetic effects on both the photochemical and thermal trans/cis isomerization of the azobenzene unit. 相似文献
168.
169.
Collisionally activated decomposition (CAD) mass spectra of the [M – C6F5CH2?]? ions of 1-methyl cster-11-pentafluorobenzyl ester-9,12,15-tris(trimethylsilyl) and 9,12,15-tris(ethyldimethylsilyl) ether derivatives of 11-dehydrothromboxane B2 are presented and discussed. The spectra are interpreted with the aid of those of a corresponding 3,3,4,4-tetradeutero compound and of an analogous derivative of 11-dehydrothromboxane B3. Proposed fragmentation pathways are based on internal consistency of data from all four compounds. The migration of a trimethylsilyl or an ethyldimethylsilyl group is the salient feature of all the CAD spectra. 相似文献
170.
Angular distributions of NO scattered off Ar and Kr in the thermal energy range are measured in crossed molecular beam experiments. Information on the anisotropy of the interaction potential is obtained from the damping of the rainbow structure within the framework of the infinite-order-sudden approximation. The derived potential energy surfaces are compared with the results of a previous experimental investigation and with the PES of the related O2-and N2-rare gas systems. 相似文献