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排序方式: 共有447条查询结果,搜索用时 31 毫秒
1.
Kaloustian J Pauli A-M Lechene de la Porte P Lafont H Portugal H 《Journal of Thermal Analysis and Calorimetry》2003,71(2):341-351
Cholesterol constitutes the major component of most gallstones. It was identified and determined, in gallstones, issued from
eleven patients, by thermal analysis: differential scanning calorimetry (DSC), with the use of the melting temperature and
enthalpy, thermogravimetry (TG), with the mass loss of water. Anhydrous cholesterol (ChA) was characterized by two endothermic
peaks (polymorphic, melting) and cholesterol monohydrate (ChH) by two endothermic peaks (dehydration, melting), too. Cha needle
and Chh plate crystals were observed under polarizing light microscopy. The numerous stones obtained from nine patients were
cholesterol stones: the ChA was higher 45 and lower 96%. ChH was present in stones of three patients.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Allais C. Keller G. Lesieur P Ollivon M. Artzner F. 《Journal of Thermal Analysis and Calorimetry》2003,74(3):723-728
Polymorphism of trilaurin mixed with 4% of cholesterol was studied with a setup coupling calorimetry and phase characterisation
by in-situ X-ray diffraction (Microcalix). Four polymorphic forms were identified. Monotropic and enantiotropic transitions
were identified from the reconstruction of Gibbs free energy diagram which allows the control of trilaurin polymorphism.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
《Arabian Journal of Chemistry》2022,15(11):104272
Yinlan lipid regulatory capsule (YL) is a composite traditional Chinese medicine (TCM) new drug to alleviate hyperlipidemia, while its therapeutic mechanism in vivo was not clarified with nontargeted metabolomics investigation. An animal model was established in rats fed a high-fat diet, and their body weights, body mass index (BMI) and blood cholesterol levels were measured. Serum, liver and kidney tissue samples were also extracted for PXR-CYP3A4-ABCB1-FXR signaling pathway research using PCR and UHPLC–MS. The obtained plasma samples were analyzed by UHPLC-Q-TOF-MS metabolomic investigation, which revealed PXR-CYP3A4-related metabolites and changes induced by YL. Finally, the key metabolites were chosen as index components, and their levels in the serum, liver, small intestine and bile were used for simultaneous UHPLC–MS-MS determination. The results indicated that YL was effective in rebalancing blood TG and TC levels (compared to controls). With respect to the PXR-CYP3A4-ABCB1 pathway, as a result of YL’s effect, gene expression or activity of the two targets decreased significantly in both the liver and kidney. The same trend was observed in the serum samples mentioned above. Metabolomics screening and data revealed that 44 metabolites can be regarded as biomarkers related to hyperlipidemia, fatty acids synthesis, and body energy consumption, as well as synthesis, transportation and exertion of cholesterol. YL’s treatment focused on 26 of them, primarily bile acids, indicating that the antihyperlipidemic effect of this drug lies in its inhibitory activity of cholesterol metabolism. Subsequent analysis of those in vivo components revealed that significant increases (compared to the model group) occurred in the blood, liver, small intestine and bile in groups that received medium and high doses of YL (while the low dose was relatively unchanged). Those target components exhibit a close relationship with PXR and/or CYP3A4. The use of YL repressed PXR expression and subsequently decreased CYP3A4 activity. As a result, synthesis of related bile acids increased, while cholesterol levels decreased, consequently leading to the attenuation of hyperlipidemia. This study comprehensively investigated the antihyperlipidemia mechanism of YL based on its repression of PXR-CYP3A4 activity and related metabolite yield, establishing an accurate method for evaluating the therapeutic effect of YL. 相似文献
4.
Varietal compounds have been analyzed in wines prepared in the laboratory from four grape varieties grown in Spain. The possibilities for enhancing their aroma afforded by addition of glycosidase enzymes and steeping with the skin were studied. Both treatments increased substances responsible for varietal aroma in all wines, the effect being particularly significant for benzyl alcohol. 相似文献
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7.
Lecithin/propanol-based microemulsions used as media for a cholesterol oxidase-catalyzed reaction 总被引:1,自引:0,他引:1
Reverse micelles, Winsor III and IV systems were examined as reaction media for the enzymatic conversion of cholesterol to cholestenone by cholesterol oxidase at 298.2 K. The micelles and the microemulsions, stabilized by soybean lecithin and ethanol or 1-propanol as cosolvent, were characterized with respect to phase behavior and distribution of 1-propanol between the phases of the Winsor III systems. The used oils were dodecane, tetradecane, and hexadecane. The Winsor IV systems and the surfactant-rich phase in the Winsor III systems exhibit bicontinuous structures. The reaction yield for the enzymatic conversion performed in a Winsor IV system was much higher than in a Winsor III system or in reverse micelles. 相似文献
8.
J. Kaloustian Paulette Lechene De La Porte T. El-Moselhy H. Lafont H. Portugal 《Journal of Thermal Analysis and Calorimetry》2005,82(2):331-338
Summary Cholesterol constitutes the major component of most gallstones. It was identified and determined in gallstones by thermal
analysis technique (DSC and TG-DTA), mainly by the use of the melting temperature (Tonset=145°C and Tmax=149°C) and by DTG peak decomposition (Tmax=364°C). Cholesterol anhydrous (ChA), which showed endothermic polymorphic peak, Tmax=40°C, without mass loss, was differentiated from cholesterol monohydrate (ChH), which showed a broad endothermic peak, Tmax=59°C, attributed to loss of water of crystallization (theoretical 4.45%). Morphological studies of gallstones were performed
by optical microscopy and scanning electron microscopy (SEM). The stones consisted of a pigmented core with a variably-sized
irregular central cavity, surrounded by a radially arranged deposits of plate-like ChH. The outer part of the stones showed
ChA crystal arborescences. X-ray microanalysis gave a typical spectrum rich in C and O, and in some instances the presence
of P, which was attributed to the presence of phospholipids. CaCO3 was easily characterized by TG with the use of DTG decomposition peak at 674°C. 相似文献
9.
Camera E Picardo M Presutti C Catarcini P Fanali S 《Journal of separation science》2004,27(12):971-976
We developed a simple and reliable analytical method for the quantification and the characterization of ceramides extracted from biological samples by high-performance liquid chromatography (HPLC) coupled to electrospray ionisation tandem mass spectrometry (ESI/MS/MS). The chromatographic separation of analytes was carried out in a RP8 column, eluting with a methanol-water mixture in gradient elution mode. The separated lipids were detected by total ion monitoring and characterised by MS/MS spectra; quantitative analysis was performed by integrating the extracted ion peaks obtained in the negative ion mode. Good repeatability was obtained for retention time (0.3-2%), peak area ratio (A(S)/A(IS), 2-8%), as well as limit of detection (LOD, 5-26 pg) and quantification (LOQ, 13-53 pg). The method was validated for the analysis of N-palmitoyl-D-erythro-sphingosine (Cer16), N-stearoyl-D-erythro-sphingosine (Cer18), N-tetracosanoyl-D-erythro-sphingosine (N24:0, lignoceric ceramide, Cer24:0), and N-tetracos-15'-enoyl-D-erythro-sphingosine (N24:1, nervonic ceramide, Cer24:1), giving good results. Lipid mixtures, extracted from skin and epidermal cells, were analysed for their content of the studied ceramides. 相似文献
10.
Khaja Basheeruddin Vicki Rothman Simeon Margolis 《Applied biochemistry and biotechnology》1985,11(2):133-140
We have immobilized E.coli alkaline phosphatase (EC 3.1.3.1) by linking it covalently to sepharose 4B. This preparation has several advantages over
the soluble enzyme. The immobilized enzyme is easily separable from other constituents in incubation mixtures. The immobilized
enzyme can be reused repeatedly and is more stable than the soluble enzyme to heat treatment in the presence of 10 mM Mg2+. The insoluble and soluble phosphatases removed 75 and77%, respectively, of the inorganic phosphorus from casein. The immobilized enzyme inactivated two enzymes believed to be active
in the phosphorylated state, acyl-CoA : cholesterol acyltransferase (ACAT) by 39% and NADPH-cytochrome P-450 reductase by
89%. The utility of immobilized alkaline phosphatase for studying the phosphorylation and dephosphorylation of soluble or
membrane-bound enzymes and proteins is discussed. 相似文献