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971.
总结了采用溶剂萃取法在盐湖卤水中提取锂资源的三类萃取剂:酸性萃取剂、中性络合萃取剂和碱性萃取剂,分析了三类不同萃取剂在萃取锂工艺过程的优缺点,指出了溶剂萃取法从高镁锂比的盐湖卤水中萃取提锂尚待攻克的技术难题。 相似文献
972.
973.
A simplified UV spectrometric method for determination of peroxide value in thermally oxidized canola oil 总被引:2,自引:0,他引:2
The aim of present study was to develop a simple method on UV spectrometer for the determination of peroxide value (PV) of the frying oil. The basis of the PV determination was the stoichiometric reaction of triphenylphosphine (TPP) with the hydroperoxides present in frying oil to produce triphenylphosphine oxide (TPPO), which exhibits a readily measurable absorption band at 240 nm by ultraviolet region. The PV ranged between 0.15 and 11.66 meq. of active oxygen per kilogram of oil as the canola oil was heated from 0 to 12 h in the fryer at 180 °C. The proposed method was correlated with official AOCS titration method and best correlation coefficient (R2 = 0.99525) was achieved, proving that there is no significant difference in the results. Therefore, developed method could serve as an alternative to the titration method, for the determination of PV in frying oils. 相似文献
974.
A pressurised liquid extraction (PLE) method for extraction and quantification of total fat and oil in bread and derivatives products has been proposed. Parameters implied in the extraction process; such us temperature, static time, number of extraction cycles, purge time and flush volume; have been optimised using a formal methodology based on statistical experimental design in order to obtain the best results. Moreover, this method has been validated using homemade bread elaborated in the laboratory which contained 9.64 g of olive oil in 100 g dry weight. The production and use of an “ad hoc” in-house reference material is just one of the most relevant aspects of this study. The uncertainty estimation has been carried out taking into account all the uncertainty components of the process and it was stated as 4.2%. Finally, the proposed method has been applied to six different Spanish bread derivatives products with different olive oil contents (5-20%) to determine the fat content. 相似文献
975.
Though liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS2) has been widely used in the structural elucidation of triacylglycerols (TAG) in vegetable oils, its potentiality for the identification of TAG molecules in omega-3 rich oils remains unexplored till date. Hence, this article investigates the applicability of LC-ESI-MS2 for the structural characterization of naturally occurring TAG in cod liver oil without the TAG fractionation during the sample preparation. A computational algorithm was developed to automatically interpret the mass spectra and elucidate the TAG structures respectively. The results were compared against the lipase benchmark method. A principal component analysis study revealed that it is possible to discriminate genuine from adulterated cod liver oil. 相似文献
976.
Unlike polyhydroxyalkanoates (PHAs) copolymers, the controlled and efficient synthesis of PHA terpolymers from triglycerides and fatty acids are yet to be established. This study demonstrates the production of P(3HB-co-3HV-co-3HHx) terpolymer with a wide range of 3HV monomer compositions from mixtures of crude palm kernel oil and 3HV precursors using a mutant Cupriavidus necator PHB−4 transformant harboring the PHA synthase gene (phaC) of a locally isolated Chromobacterium sp. USM2. The PHA synthase of Chromobacterium has an unusually high affinity towards 3HV monomer. P(3HB-co-3HV-co-3HHx) terpolymers with 3HV monomer composition ranging from 2 to 91 mol% were produced. Generation of 3HHx monomers was affected by the concentration and feeding time of 3HV precursor. P(3HB-co-24 mol% 3HV-co-7 mol% 3HHx) exhibited mechanical properties similar to that of common low-density polyethylene. P(3HB-co-3HV-co-3HHx) terpolymers with a wide range of 3HV molar fraction had been successfully synthesized by adding lower concentrations of 3HV precursors and using a PHA synthase with high affinity towards 3HV monomer. 相似文献
977.
Mohd Rafein Zakaria Hidayah Ariffin Suraini Abd-Aziz Yoshihito Shirai 《Polymer Degradation and Stability》2010,95(8):1382-1386
Poly(3-hydroxybutyrate) [P(3HB)] homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] copolymer was produced by Comamonas sp. EB172 using single and mixture of carbon sources. Poly(3-hydroxyvalerate) P(3HV) incorporation in the copolymer was obtained when propionic and valeric acid was used as precursors. Incorporation of 3HV fractions in the copolymer varied from 45 to 86 mol% when initial pH of the medium was regulated. In fed-batch cultivation, organic acids derived from anaerobically treated palm oil mill effluent (POME) were shown to be suitable carbon sources for polyhydroxyalkanoate (PHA) production by Comamonas sp. EB172. Number average molecular weight (Mn) produced by the strain was in the range of 153-412 kDa with polydispersity index (Mw/Mn) in the range of 2.2-2.6, respectively. Incorporation of higher 3HV units improved the thermal stability of P(3HB-co-3HV) copolymer. Thus the newly isolated bacterium Comamonas sp. EB172 is a suitable candidate for PHA production using POME as renewable and alternative cheap raw materials. 相似文献
978.
Chunhua Fu Changshun Ruan Ya Fu Yuanliang Wang 《Polymer Degradation and Stability》2010,95(4):485-490
The multi-arm star polymer (ESOPLA) was obtained by ring-opening polymerization of dl-lactide using multifunctional epoxidized soybean oil (ESO) as an initiator in the presence of a stannous actuate (SnOct2) catalyst. Gel permeation chromatography with multi-angle laser light scattering (GPC-MALLS), FTIR, 1H NMR, thermal analysis and in vitro degradation were used to qualitatively characterize the synthesized polymers. The results revealed that ESO plays an important role in increasing the molecular weight, polymerization rate and monomer conversion rate. Degradation analysis demonstrated that the decrease in molecular weight and the weight loss ratio of the star-shaped ESOPLA were lower than that of linear poly(dl-lactide) (PDLLA). The surface topography of pre- and post-degradation materials was characterized by scanning electron microscopy (SEM). These SEM images showed that the linear PDLLA films underwent water erosion more readily than the star-shaped polymer films. 相似文献
979.
We attempted to synthesize novel polyhydroxyalkanoate (PHA) containing new 3-hydroxy-4-methylvalerate (3H4MV) monomer from the transformed strain of Cupriavidus necator PHB−4 harboring the PHA synthase gene of Chromobacterium sp. USM2 (phaCCs). Novel PHA containing SCL and MCL monomers were successfully synthesized from crude palm kernel oil (CPKO) and isocaproic acid. Results showed that P(3HB-co-1 mol% 3HV-co-3 mol% 3H4MV-co-18 mol% 3HHx) possessed higher thermal stability, higher elastomeric behavior at room temperature and higher ductility than the P(3HB-co-5 mol% 3HHx). The novel PHA film was found to possess an interesting rubber-like elasticity and flexibility property which has not been reported. The soil surface degradation study showed that the novel PHA film was degraded faster than the 3HB homopolymer and copolymer with 5 mol% of 3HHx. 相似文献
980.
Rocío García‐Villalba Alegría Carrasco‐Pancorbo Gabriela Zurek Marina Behrens Carsten Bäßmann Antonio Segura‐Carretero Alberto Fernández‐Gutiérrez 《Journal of separation science》2010,33(14):2069-2078
The applicability of nanoLC‐ESI‐TOF MS for the analysis of phenolic compounds in olive oil was studied and compared with a HPLC method. After the injection, the compounds were focused on a short capillary trapping column (100 μm id, effective length 20 mm, 5 μm particle size) and then nanoLC analysis was carried out in a fused silica capillary column (75 μm id, effective length 10 μm, 3 μm particle size) packed with C18 stationary phase. The mobile phase was a mixture of water + 0.5% acetic acid and ACN eluting at 300 nL/min in a gradient mode. Phenolic compounds from different families were identified and quantified. The quality parameters of the nanoLC method (linearity, LODs and LOQs, repeatability) were evaluated and compared with those obtained with HPLC. The new methodology presents better sensitivity (reaching LOD values below 1 ppb) with less consumption of mobile phases, but worse repeatability, especially inter‐day repeatability, resulting in more difficulties to get highly accurate quantification. The results described in this article open up the application fields of this technique to cover a larger variety of compounds and its advantages will make it especially useful for the analysis of samples containing low concentration of phenolic compounds, as for instance, in biological samples. 相似文献