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排序方式: 共有198条查询结果,搜索用时 15 毫秒
91.
This research present an integrated process for the extraction and purification of betanin from fruit of Opuntia ficus-indica. The extraction process was evaluated using different solvents (water, acetonitrile, ethanol and tetrahydrofuran), and then integrated into the purification process using aqueous two-phase systems (ATPS). The optimum conditions for extraction was with THF and the purification conditions determined to be 43 wt% of THF and 6 wt% of sodium citrate buffer (pH 5.5) at 25°C. A purification factor of 13.7 ± 0.5 fold, with a partition coefficient of betanin for salt-rich phase and the antioxidant capacity was increased ≈ 65%.  相似文献   
92.
In recent years, sulfamic acid (SA, NH2SO3H) has emerged as a novel green catalyst for organic synthesis because of several advantages, including its non‐volatility, non‐hygroscopicity, non‐corrosivity, and low cost. This work reports the use of sulfamic acid as a catalyst in the pretreatment of oil with a high content of free fatty acids (10 and 20 % FFA) in ethanol or methanol. The process (esterification reaction) used in the pretreatment of the oil was carried out under a variety of conditions, initial fatty acid content, temperature, type of alcohol, and % catalyst. The experiments using an NH2SO3H/ethanol system resulted in a high fatty acid ethyl ester conversion, 88.53 % (±0.95) from an initial acidity of 40 mg KOH/g (20 % FFA), using 8 % NH2SO3H as the catalyst. According to the results, the methodology using sulfamic acid and ethanol demonstrated elevated potential for a environmentally‐friendly means of biodiesel production.  相似文献   
93.
Laccase production by Pycnoporus sanguineus RP15 grown in wheat bran and corncob under solid-state fermentation was optimized by response surface methodology using a Central Composite Rotational Design. A laccase (Lacps1) was purified and characterized and the potential of the pure Lacps1 and the crude culture extract for synthetic dye decolorization was evaluated. At optimal conditions (eight days, 26 °C, 18% (w/w) milled corncob, 0.8% (w/w) NH4Cl and 50 mmol·L−1 CuSO4, initial moisture 4.1 mL·g−1), the laccase activity reached 138.6 ± 13.2 U·g−1. Lacps1 was a monomeric glycoprotein (67 kDa, 24% carbohydrate). Optimum pH and temperature for the oxidation of 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) were 4.4 and 74.4 °C, respectively. Lacps1 was stable at pH 3.0–8.0, and after two hours at 55–60 °C, presenting high redox potential (0.747 V vs. NHE). ABTS was oxidized with an apparent affinity constant of 147.0 ± 6.4 μmol·L−1, maximum velocity of 413.4 ± 21.2 U·mg−1 and catalytic efficiency of 3140.1 ± 149.6 L·mmol−1·s−1. The maximum decolorization percentages of bromophenol blue (BPB), remazol brilliant blue R and reactive blue 4 (RB4), at 25 or 40 °C without redox mediators, reached 90%, 80% and 60%, respectively, using either pure Lacps1 or the crude extract. This is the first study of the decolorization of BPB and RB4 by a P. sanguineus laccase. The data suggested good potential for treatment of industrial dye-containing effluents.  相似文献   
94.
Passiflora edulis by-products (PFBP) are a rich source of polyphenols, of which piceatannol has gained special attention recently. However, there are few studies involving environmentally safe methods for obtaining extracts rich in piceatannol. This work aimed to concentrate piceatannol from defatted PFBP (d-PFBP) by means of pressurized liquid extraction (PLE) and conventional extraction, using the bio-based solvents selected with the Hansen solubility parameters approach. The relative energy distance (Ra) between solvent and solute was: Benzyl Alcohol (BnOH) < Ethyl Acetate (EtOAc) < Ethanol (EtOH) < EtOH:H2O. Nonetheless, EtOH presented the best selectivity for piceatannol. Multi-cycle PLE at 110 °C was able to concentrate piceatannol 2.4 times more than conventional extraction. PLE exhibited a dependence on kinetic parameters and temperature, which could be associated with hydrogen bonding forces and the dielectric constant of the solvents. The acetylcholinesterase (AChE) and lipoxygenase (LOX) IC50 were 29.420 μg/mL and 27.682 μg/mL, respectively. The results reinforce the demand for processes to concentrate natural extracts from food by-products.  相似文献   
95.
Objective: V565 is a novel oral anti-tumor necrosis factor (TNF)-α domain antibody being developed for topical treatment of inflammatory bowel disease (IBD) patients. Protein engineering rendered the molecule resistant to intestinal proteases. Here we investigate the formulation of V565 required to provide gastro-protection and enable optimal delivery to the lower intestinal tract in monkeys.

Methods: Enteric-coated V565 mini-tablets were prepared and dissolution characteristics tested in vitro. Oral dosing of monkeys with enteric-coated mini-tablets containing V565 and methylene blue dye enabled in vivo localization of mini-tablet dissolution. V565 distribution in luminal contents and feces was measured by enzyme-linked immunosorbent assay (ELISA). To mimic transit across the damaged intestinal epithelium seen in IBD patients an intravenous (i.v.) bolus of V565 was given to monkeys and pharmacokinetic parameters of V565 measured in serum and urine by ELISA.

Results: Enteric-coated mini-tablets resisted dissolution in 0.1?M HCl, before dissolving in a sustained release fashion at neutral pH. In orally dosed monkeys methylene blue intestinal staining indicated the jejunum and ileum as sites for mini-tablet dissolution. Measurements of V565 in monkey feces confirmed V565 survival through the intestinal tract. Systemic exposure after oral dosing was very low consistent with limited V565 mucosal penetration in healthy monkeys. The rapid clearance of V565 after i.v. dosing was consistent with renal excretion as the primary route for elimination of any V565 reaching the circulation.

Conclusions: These results suggest that mini-tablets with a 24% Eudragit enteric coating are suitable for targeted release of orally delivered V565 in the intestine for topical treatment of IBD.  相似文献   

96.
Electromechanical coupling through piezoelectric polymer chains allows the emission of organic molecules in active nanowires to be tuned. This effect is evidenced by highly bendable arrays of counter‐ion dye‐doped nanowires made of a poly(vinylidenefluoride) copolymer. A reversible redshift of the dye emission is found upon the application of dynamic stress during highly accurate bending experiments. By density functional theory calculations it is found that these photophysical properties are associated with mechanical stresses applied to electrostatically interacting molecular systems, namely to counterion‐mediated states that involve light‐emitting molecules as well as charged regions of piezoelectric polymer chains. These systems are an electrostatic class of supramolecular functional stress‐sensitive units, which might impart new functionalities in hybrid molecular nanosystems and anisotropic nanostructures for sensing devices and soft robotics.  相似文献   
97.
98.
Emulsions inversion occurs in many industrial processes and may be influenced by the formulation conditions, composition and emulsification protocols. In this work, the influence of emulsifiers and stirring on catastrophic inversion (O/W to W/O) was evaluated. Emulsions were prepared with different stirring rates, using soy lecithin and Tween 80, at 2 and 5 wt%. The aqueous phase was distilled water with 1 wt% NaCl and the oil phase was soy oil. These emulsions were analyzed by conductivity, stability, microscopy and rheology assays. The most stable emulsions presented inversion with a smaller amount of the external phase. Rheological analysis showed that, with a higher concentration of emulsifier, it is better to use Tween 80 when lower viscosity is desired, while soy lecithin is more appropriate for higher viscosity products. The oscillatory tests showed that while the emulsions prepared using Tween 80 exhibited concentrated solution behavior, those prepared with soy lecithin exhibited strong gel behavior.  相似文献   
99.
The aim of the study was to evaluate the effect of high hydrostatic pressure (HHP) on the appearance, bioactivity and microbial content of four edible flowers along storage. Several treatments at 75–450 MPa and holding times (1, 5 and 10 min) were applied. Borage and camellia were unacceptable after all treatments, while centaurea showed good appearance at 100/5 MPa min?1; however, the shelf life did not increase. Pansies treated at 75/5 and 75/10 MPa min?1 also retained the appearance of fresh flowers. Furthermore, pansies submitted at 75/5 MPa min?1 maintained good appearance over 20 days of storage at 4 °C, while the untreated remained satisfactory only until 6 days. Even though no significant differences on microbial load were observed between untreated and HHP‐treated pansies in day 0, HHP induced the production of bioactive compounds, increasing the shelf life of pansies. So, the HHP treatment is a promising technology for Viola × wittrockiana.  相似文献   
100.
A simple, fast, and efficient method was developed for simultaneous determination of 79 pesticides and 13 antibiotics compounds of different chemical classes of pesticides and antibiotics in honey samples by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). The sample preparation procedure includes homogenization with McIlvaine buffer 0.1 mol L?1 (pH 4), followed by extraction with acetonitrile and cleanup with florisil, using dispersive solid phase extraction (d-SPE). The proposed method was validated with good results, such as linearity (r 2?>?0.9901), normality, and independence of the evaluated data, as well as recoveries between 70 and 120 % with relative standard deviation (RSD) <20 % for most of the compounds spiked from 0.1 to 200 μg kg?1. The experimental method limits of detection and quantification were from 0.03 to 1.51 μg kg?1 and from 0.1 to 5 μg kg?1, respectively, for the pesticides. For the antibiotics, the decision limits (0.1 to 2 μg g?1) and the detection capacity (0.12 to 2.81 μg g?1) were below the maximum residue limits (MRLs) established for honey by the Brazilian and European legislation. The method was successfully applied to real samples from different botanical and geographic origins. From them, 44 % presented residues from 0.12 to 10 μg kg?1 of one or more analytes. The proposed method combines the advantages of a quick sample preparation step with the selectivity and sensitivity of the UHPLC-MS/MS and proved to be suitable for routine analyses.  相似文献   
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