全文获取类型
收费全文 | 127篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 91篇 |
数学 | 6篇 |
物理学 | 37篇 |
出版年
2022年 | 16篇 |
2021年 | 17篇 |
2020年 | 13篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 6篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1959年 | 2篇 |
1958年 | 1篇 |
1955年 | 1篇 |
1910年 | 1篇 |
1882年 | 1篇 |
1881年 | 1篇 |
排序方式: 共有134条查询结果,搜索用时 15 毫秒
11.
Anna Michnik Ewa Sadowska-Krępa Przemysław Domaszewski Klaudia Duch Ilona Pokora 《Journal of Thermal Analysis and Calorimetry》2017,130(3):1253-1262
Differential scanning calorimetry (DSC) has been used for the detection of post-exercise changes in blood serum resulting from participation in the CrossFit (CF) training combined with green tea extract (GTE) supplementation. Blood samples from 20 well-trained men were collected at rest, immediately post-exercise and after 1 h of recovery in two trials: first before and second after CF training combined with GTE or placebo administration in the supplemented (S) and control (C) groups, respectively. Selected muscle damage biomarkers have been compared in different phases of the experiment. A significant increase in blood lactate content has been observed post-exercise in both trials in both participants’ groups. The opposite trends have been noted for the C and S groups in creatine kinase (CK) activity changes recorded during the first to the second trial: an increase in CK for the control and a decrease for the supplemented group in all phases of the experiment: pre-exercise, post-exercise and after recovery. In the second trial, all CK values for the S group have been found significantly lower than the corresponding values recorded in the C group. These results suggest a mitigate effect of GTE supplementation on post-training muscle damage. DSC results did not reveal clear effects of training nor GTE supplementation on serum denaturation transition. However, interesting dependences of thermodynamic parameters describing this transition have been observed in different phases of the experiment. Statistically significant negative correlations have been found between post-training VO2max and post-exercise thermodynamic parameters associated with haptoglobin contribution to serum denaturation transition. 相似文献
12.
S. Hüfner P. Kienle D. Quitmann P. Brix 《Zeitschrift für Physik A Hadrons and Nuclei》1965,187(1):67-84
The isomer shift of the 21.7 keVγ transition in Eu151 has been studied for various divalent and trivalent europium compounds using the Mössbauer technique. Theγ energy is lower by up to 1.1·10?6 eV in divalent compounds than in trivalent compounds. Using data from atomic spectroscopy it is estimated that the electron density at the nucleus is larger by about 1.9·1026cm?3 for the configuration 4f 6 than for 4f 7 due to different shielding of thes 2 shells. The difference of the mean square radii of the 21.7 keV state and the ground state is thenδ〈r2〉=+0.03 fm2. The measured isomer shift between trivalent and metallic europium and the relatives-electron densities in the rare earth metals measured by the positron annihilation rates are used to establish a calibration scheme for isomer shifts in rare earth metals. This calibration scheme is used to deduce a changeδ〈r 2〉=+0.0055 fm2 between the 26 keV state and the ground state of Dy161. 相似文献
13.
How to confirm identified toxicants in effect-directed analysis 总被引:1,自引:0,他引:1
Brack W Schmitt-Jansen M Machala M Brix R Barceló D Schymanski E Streck G Schulze T 《Analytical and bioanalytical chemistry》2008,390(8):1959-1973
Due to the production and use of a multitude of chemicals in modern society, waters, sediments, soils and biota may be contaminated
with numerous known and unknown chemicals that may cause adverse effects on ecosystems and human health. Effect-directed analysis
(EDA), combining biotesting, fractionation and chemical analysis, helps to identify hazardous compounds in complex environmental
mixtures. Confirmation of tentatively identified toxicants will help to avoid artefacts and to establish reliable cause–effect
relationships. A tiered approach to confirmation is suggested in the present paper. The first tier focuses on the analytical
confirmation of tentatively identified structures. If straightforward confirmation with neat standards for GC–MS or LC–MS
is not available, it is suggested that a lines-of-evidence approach is used that combines spectral library information with
computer-based structure generation and prediction of retention behaviour in different chromatographic systems using quantitative
structure–retention relationships (QSRR). In the second tier, the identified toxicants need to be confirmed as being the cause
of the measured effects. Candidate components of toxic fractions may be selected based, for example, on structural alerts.
Quantitative effect confirmation is based on joint effect models. Joint effect prediction on the basis of full concentration–response
plots and careful selection of the appropriate model are suggested as a means to improve confirmation quality. Confirmation
according to the Toxicity Identification Evaluation (TIE) concept of the US EPA and novel tools of hazard identification help
to confirm the relevance of identified compounds to populations and communities under realistic exposure conditions. Promising
tools include bioavailability-directed extraction and dosing techniques, biomarker approaches and the concept of pollution-induced
community tolerance (PICT).
Figure Toxicity confirmation in EDA as a tiered approach 相似文献
14.
Klaudia Stando Patrycja Kasprzyk Ewa Felis Sylwia Bajkacz 《Molecules (Basel, Switzerland)》2021,26(24)
Metronidazole (MET) is a commonly detected contaminant in the environment. The compound is classified as poorly biodegradable and highly soluble in water. Heterogeneous photocatalysis is the most promoted water purification method due to the possibility of using sunlight and small amounts of a catalyst needed for the process. The aim of this study was to select conditions for photocatalytic removal of metronidazole from aquatic samples. The effect of catalyst type, mass, and irradiance intensity on the efficiency of metronidazole removal was determined. For this purpose, TiO2, ZnO, ZrO2, WO3, PbS, and their mixtures in a mass ratio of 1:1 were used. In this study, the transformation products formed were identified, and the mineralization degree of compound was determined. The efficiency of metronidazole removal depending on the type of catalyst was in the range of 50–95%. The highest MET conversion (95%) combined with a high degree of mineralization (70.3%) was obtained by using a mixture of 12.5 g TiO2–P25 + PbS (1:1; v/v) and running the process for 60 min at an irradiance of 1000 W m−2. Four MET degradation products were identified by untargeted analysis, formed by the rearrangement of the metronidazole and the C-C bond breaking. 相似文献
15.
Michnik Anna Kiełboń Agnieszka Duch Klaudia Sadowska-Krępa Ewa Pokora Ilona 《Journal of Thermal Analysis and Calorimetry》2022,147(12):6739-6743
Journal of Thermal Analysis and Calorimetry - The results of studies of physiological fluids by differential scanning calorimetry (DSC) for the purpose of diagnosis and monitoring of diseases are... 相似文献
16.
Complete (1)H and (13)C NMR signal assignments of two lactucin-type sesquiterpene lactone glycosides, derivatives of 11β,13-dihydrolactucin, isolated from roots of Picris conyzoides, were achieved by one- and two-dimensional NMR experiments, allowing the correction of previously published data for cichorioside B and the structure elucidation of its new ester with 3-hydroxy-2-methylpropanoic acid. In addition, seven known sesquiterpene lactones and three phenolic compounds were isolated from the plant material. 相似文献
17.
Dr. Samuel M. Meier M. Sc. Dominique Kreutz Dr. Lilli Winter M. Sc. Matthias H. M. Klose M. Sc. Klaudia Cseh M. Sc. Tamara Weiss Dr. Andrea Bileck M. Sc. Beatrix Alte Dr. Johanna C. Mader M. Sc. Samir Jana Dr. Annesha Chatterjee Dr. Arindam Bhattacharyya Michaela Hejl Dr. Michael A. Jakupec Priv.-Doz. Dr. Petra Heffeter Prof. Dr. Walter Berger Prof. Dr. Christian G. Hartinger Prof. Dr. Bernhard K. Keppler Prof. Dr. Gerhard Wiche Prof. Dr. Christopher Gerner 《Angewandte Chemie (International ed. in English)》2017,56(28):8267-8271
Organometallic metal(arene) anticancer agents require ligand exchange for their anticancer activity and this is generally believed to confer low selectivity for potential cellular targets. However, using an integrated proteomics-based target-response profiling approach as a potent hypothesis-generating procedure, we found an unexpected target selectivity of a ruthenium(arene) pyridinecarbothioamide (plecstatin) for plectin, a scaffold protein and cytolinker, which was validated in a plectin knock-out model in vitro. Plectin targeting shows potential as a strategy to inhibit tumor invasiveness as shown in cultured tumor spheroids while oral administration of plecstatin-1 to mice reduces tumor growth more efficiently in the invasive B16 melanoma than in the CT26 colon tumor model. 相似文献
18.
MicroRNAs as biomarkers of disease onset 总被引:1,自引:0,他引:1
Ciesla M Skrzypek K Kozakowska M Loboda A Jozkowicz A Dulak J 《Analytical and bioanalytical chemistry》2011,401(7):2051-2061
19.
Sulodexide (SDX), a purified glycosaminoglycan mixture used to treat vascular diseases, has been reported to exert endothelial protective effects against ischemic injury. However, the mechanisms underlying these effects remain to be fully elucidated. The emerging evidence indicated that a relatively high intracellular concentration of reduced glutathione (GSH) and a maintenance of the redox environment participate in the endothelial cell survival during ischemia. Therefore, the aim of the present study was to examine the hypothesis that SDX alleviates oxygen–glucose deprivation (OGD)-induced human umbilical endothelial cells’ (HUVECs) injury, which serves as the in vitro model of ischemia, by affecting the redox state of the GSH: glutathione disulfide (GSSG) pool. The cellular GSH, GSSG and total glutathione (tGSH) concentrations were measured by colorimetric method and the redox potential (ΔEh) of the GSSG/2GSH couple was calculated, using the Nernst equation. Furthermore, the levels of the glutamate–cysteine ligase catalytic subunit (GCLc) and the glutathione synthetase (GSS) proteins, a key enzyme for de novo GSH synthesis, were determined using enzyme-linked immunoassay (ELISA). We demonstrated that the SDX treatment in OGD conditions significantly elevated the intracellular GSH, enhanced the GSH:GSSG ratio, shifting the redox potential to a more pro-reducing status. Furthermore, SDX increased the levels of both GCLc and GSS. The results show that SDX protects the human endothelial cells against ischemic stress by affecting the GSH levels and cellular redox state. These changes suggest that the reduction in the ischemia-induced vascular endothelial cell injury through repressing apoptosis and oxidative stress associated with SDX treatment may be due to an increase in GSH synthesis and modulation of the GSH redox system. 相似文献
20.