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排序方式: 共有1574条查询结果,搜索用时 421 毫秒
971.
Ismael Ivan Rockenbach Eliseu Rodrigues Luciano Valdemiro Gonzaga Vinícius Caliari Maria Inés Genovese Any Elisa de Souza Schmidt Gonçalves Roseane Fett 《Food chemistry》2011
The phenolic compounds content and antioxidant activity of pomace from the vinification of grape varieties widely produced in Brazil (Cabernet Sauvignon, Merlot, Bordeaux and Isabel) were investigated with a view to their exploitation as a potential source of natural antioxidants. Cabernet Sauvignon grape pomace was found to have the highest content of total phenolic compounds (74.75 mg gallic acid equivalent (GAE)/g), the highest antioxidant activity (determined using the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging methods; 485.42 and 505.52 μMol Trolox equivalent antioxidant capacity (TEAC)/g, respectively), and the highest reducing power (determined using the FRAP method; 249.46 μMol TEAC/g). The Bordeaux variety showed the highest oxidation inhibition power (41.13%), determined using the β-carotene/linoleic acid method and the highest content of total anthocyanins (HPLC; 29.17 mg/g). Catechin was the most abundant non-anthocyanic compound identified in the grape pomace (150.16 mg/100 g) for all varieties. In this study, pomaces of the red wine vinification of Cabernet Sauvignon and Bordeaux varieties showed the highest potential as a source of antioxidant compounds and natural colourants, respectively. 相似文献
972.
Chlorophyll a fluorescence of microalgae is a compelling indicator of toxicity of dissolved water contaminants, because it is easily measured and responds rapidly. While different chl a fluorescence parameters have been examined, most studies have focused on single species and/or a narrow range of toxins. We assessed the utility of one chl a fluorescence parameter, the maximum quantum yield of PSII (Fv/Fm), for detecting effects of nine environmental pollutants from a range of toxin classes on 5 commonly found freshwater algal species, as well as the USEPA model species, Pseudokirchneriella subcapitata. Fv/Fm declined rapidly over <20 min in response to low concentrations of photosynthesis-specific herbicides Diuron® and metribuzin (both <40 nM), atrazine (<460 nM) and terbuthylazine (<400 nM). However, Fv/Fm also responded rapidly and in a dose-dependent way to toxins glyphosate (<90 μM), and KCN (<1 mM) which have modes of action not specific to photosynthesis. Fv/Fm was insensitive to 30-40 μM insecticides methyl parathion, carbofuran and malathion. Algal species varied in their sensitivity to toxins. No single species was the most sensitive to all nine toxins, but for six toxins to which algal Fv/Fm responded significantly, the model species P. subcapitata was less sensitive than other taxa. In terms of suppression of Fv/Fm within 80 min, patterns of concentration-dependence differed among toxins; most showed Michaelis-Menten saturation kinetics, with half-saturation constant (Km) values for the PSII inhibitors ranging from 0.14 μM for Diuron® to 6.6 μM for terbuthylazine, compared with a Km of 330 μM for KCN. Percent suppression of Fv/Fm by glyphosate increased exponentially with concentration. Fv/Fm provides a sensitive and easily-measured parameter for rapid and cost-effective detection of effects of many dissolved toxins. Field-portable fluorometers will facilitate field testing, however distinct responses between different species may complicate net Fv/Fm signal from a community. 相似文献
973.
Mobasheri A Trujillo E Arteaga MF Martín-Vasallo P 《International journal of molecular sciences》2012,13(4):5019-5034
Membrane transport systems participate in fundamental activities such as cell cycle control, proliferation, survival, volume regulation, pH maintenance and regulation of extracellular matrix synthesis. Multiple isoforms of Na(+), K(+)-ATPase are expressed in primary chondrocytes. Some of these isoforms have previously been reported to be expressed exclusively in electrically excitable cells (i.e., cardiomyocytes and neurons). Studying the distribution of Na(+), K(+)-ATPase isoforms in chondrocytes makes it possible to document the diversity of isozyme pairing and to clarify issues concerning Na(+), K(+)-ATPase isoform abundance and the physiological relevance of their expression. In this study, we investigated the expression of Na(+), K(+)-ATPase in a human chondrocyte cell line (C-20/A4) using a combination of immunological and biochemical techniques. A panel of well-characterized antibodies revealed abundant expression of the α1, β1 and β2 isoforms. Western blot analysis of plasma membranes confirmed the above findings. Na(+), K(+)-ATPase consists of multiple isozyme variants that endow chondrocytes with additional homeostatic control capabilities. In terms of Na(+), K(+)-ATPase expression, the C-20/A4 cell line is phenotypically similar to primary and in situ chondrocytes. However, unlike freshly isolated chondrocytes, C-20/A4 cells are an easily accessible and convenient in vitro model for the study of Na(+), K(+)-ATPase expression and regulation in chondrocytes. 相似文献
974.
E Pellegrini PL Cioni A Francini G Lorenzini C Nali G Flamini 《Journal of chemical ecology》2012,38(7):924-932
The volatiles emitted from young and old leaves of two poplar clones (Populus deltoides x maximowiczii, Eridano, and P. x euramericana, I-214) were sampled after exposure to ozone (80 ppb, 5 h?d(-1), for 10 consecutive days) by solid phase microextraction and characterized by GC-MS. Only mature leaves of the ozone-sensitive Eridano clone developed necrosis in response to ozone exposure, and their membrane integrity was significantly affected by ozone (+86 and +18 % of levels of thiobarbituric acid reactive substances in mature and young leaves). The headspace of the poplar clones studied here contained mono- and sesquiterpenes, both hydrocarbons and oxygenated ones in Eridano, and only hydrocarbons in the clone I-214. Furthermore, some non-terpenes, such as C(9)-C(15) straight-chain aldehydes and C(12)-C(16) saturated and unsaturated aliphatic hydrocarbons, were detected. Other common non-terpene volatiles were oxygenated aliphatic compounds, mainly C(6)-alcohols and their acetates. Ozone exposure induced a strong change in volatile profiles, depending on clones and leaf age. Regardless of leaf age, in clone I-214, quantities of oxygenated monoterpenes tended to increase after ozone exposure, however, "O(3) x leaf age" was not significant. In clone Eridano, increases were observed in emissions of hydrocarbons and oxygenated sesquiterpenes in response to ozone treatment. (Z)-3-Hexen-1-ol and (Z)-3-hexenol acetate were present in traces in the headspace of untreated Eridano mature leaves, but quantities slightly increased after ozone treatment. Quantities of non-terpene oxygenated compounds dropped in the headspace of young leaves of both clones (-24 and -44 % in Eridano and I-214) and also in mature ones of I-214 (-50 %) after ozone exposure. Similarly, quantities of non-terpene hydrocarbons in the emissions from mature leaves of both clones (-58 and -49 %, respectively) decreased, while these compounds increased in young leaves of Eridano (+83 %). We suggest that the resistance of the poplar clone I-214 to O(3) is achieved by: i) monoterpenes constitutively present in young leaves and ii) increase of monoterpene content induced by O(3) in mature leaves. 相似文献
975.
Edgar Moctezuma Elisa Leyva Mariana López Alfonso Pinedo Brenda Zermeño Benito Serrano 《Topics in Catalysis》2013,56(18-20):1875-1882
The advanced oxidation of high purity metoprolol tartrate, extracted from a commercial medicament, with TiO2 and UV light (365 nm) was investigated to determine the effect of initial reactant concentration on the reaction rate and the role of direct photolysis on the photocatalytic process. Analysis of the reaction samples by UV–Vis spectroscopy indicated that metoprolol tartrate is efficiently degraded by photocatalysis via hydroxylation of the aromatic ring. Kinetic studies indicated that the photocatalytic degradation of metoprolol tartrate follows a Langmuir, Hinshelwood, Hougen and Watson (LHHW) mechanism where the reaction order shifts from zero order to first order as the reactant concentration drops. Additional experiments showed that direct photolysis plays a minor role on the photocatalytic oxidation of metoprolol tartrate. Total organic carbon (TOC) studies demonstrated that metoprolol tartrate is transformed to other organic intermediate reaction products before complete mineralization to CO2. The fraction of reactant transformed into intermediate organic products was evaluated by a material balance using the results of analysis of the reaction samples by high performance liquid chromatography and TOC. 相似文献
976.
Elisa Sgarbi Camilla LazziLuca Iacopino Chiara BottesiniFrancesca Lambertini Stefano Sforza Monica Gatti 《Food microbiology》2013
Cheese ripening involves a complex series of biochemical events that contribute to the development of each cheese characteristic taste, aroma and texture. Proteolysis, which has been the subject of active research in the last decade, is the most complex of these biochemical events. However, also aminoacyl derivates of non-proteolytic origin (γ-glutamyl-amino acids and lactoyl-amino acids) with interesting sensory properties have been identified in cheeses. In the present work, an enzymatic activity producing γ-glutamyl-phenylalanine in Parmigiano-Reggiano water soluble extracts was observed. It was hypothesized that γ-glutamyl-amino acids and lactoyl-amino acids could be originated by enzymes of bacterial origin. In order to confirm this hypothesis, Lactobacillus helveticus and Lactobacillus rhamnosus were chosen as representative of starter and non starter microbiota of Parmigiano Reggiano cheese. They were used as model bacteria, in the presence of suitable precursors, to verify their ability to produce γ-glutamyl-phenylalanine and lactoyl-phenylalanine. The eventual abilities of these strains were tested both during growth and after cell lyses. While γ-glutamyl-phenylalanine was produced only by lysed cells, lactoyl-phenylalanine was produced either by growing or lysed cells in different amount depending on the species, the cells condition and the time of incubation. 相似文献
977.
Marina Nadia Losio Giancarlo Bozzo Elisa Galuppini Vito Martella Barbara Bertasi Enrico Pavoni 《International Journal of Food Properties》2013,16(3):492-498
Silter cheese is a traditional hard cheese, produced in Valcamonica, Brescia, Italy. A total of 426 lactic strains isolated from Silter were analyzed to determine their probiotic characteristics. 274 out of 426 strains were found to produce bacteriocins against at least one of eight different pathogens (Salmonella enterica, Listeria monocytogenes, Salmonella derby, Salmonella thyphimurium, Salmonella napoli, Staphylococcus aureus, E. coli O157:H7, Salmonella enteritidis). In addition, 211 of 274 bactericin-producer strains adhered to Caco-2 cells and were characterized by RiboPrinter, revealing predominance of Enterococcus faecalis (26%) and Enterococcus durans-faecium (22%). These findings suggest that Silter may qualify as an important source of feasible probiotic strains. 相似文献
978.
Cavalli S Houben AJ Albers HM van Tilburg EW de Ru A Aoki J van Veelen P Moolenaar WH Ovaa H 《Chembiochem : a European journal of chemical biology》2010,11(16):2311-2317
Autotaxin (ATX), or ecto-nucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2), is a secreted lysophospholipase D that hydrolyses lysophosphatidylcholine into the lipid mediator lysophosphatidic acid (LPA), a mitogen and chemoattractant for many cell types. ATX has been implicated in tumour progression and inflammation, and might serve as a biomarker. Here we describe the development of a fluorescent activity-based probe that covalently binds to the active site of ATX. The probe consists of a lysophospholipid-based backbone linked to a trapping moiety that becomes reactive after phosphate ester hydrolysis, and a Cy5 fluorescent dye to allow visualisation of active ATX. The probe reacts specifically with the three known isoforms of ATX, it competes with small-molecule inhibitors for binding to ATX and allows ATX activity in plasma to be determined. Our activity-based reporter will be useful for monitoring ATX activity in biological fluids and for inhibitor screening. 相似文献
979.
Dânia Elisa Christofoletti Mazzeo Dejanira de Franceschi de Angelis 《The Science of the total environment》2010,408(20):4334-294
Groundwater contamination with benzene, toluene, ethylbenzene and xylene (BTEX) has been increasing, thus requiring an urgent development of methodologies that are able to remove or minimize the damages these compounds can cause to the environment. The biodegradation process using microorganisms has been regarded as an efficient technology to treat places contaminated with hydrocarbons, since they are able to biotransform and/or biodegrade target pollutants. To prove the efficiency of this process, besides chemical analysis, the use of biological assessments has been indicated. This work identified and selected BTEX-biodegrading microorganisms present in effluents from petroleum refinery, and evaluated the efficiency of microorganism biodegradation process for reducing genotoxic and mutagenic BTEX damage through two test-systems: Allium cepa and hepatoma tissue culture (HTC) cells. Five different non-biodegraded BTEX concentrations were evaluated in relation to biodegraded concentrations. The biodegradation process was performed in a BOD Trak Apparatus (HACH) for 20 days, using microorganisms pre-selected through enrichment. Although the biodegradation usually occurs by a consortium of different microorganisms, the consortium in this study was composed exclusively of five bacteria species and the bacteria Pseudomonas putida was held responsible for the BTEX biodegradation. The chemical analyses showed that BTEX was reduced in the biodegraded concentrations. The results obtained with genotoxicity assays, carried out with both A. cepa and HTC cells, showed that the biodegradation process was able to decrease the genotoxic damages of BTEX. By mutagenic tests, we observed a decrease in damage only to the A. cepa organism. Although no decrease in mutagenicity was observed for HTC cells, no increase of this effect after the biodegradation process was observed either. The application of pre-selected bacteria in biodegradation processes can represent a reliable and effective tool in the treatment of water contaminated with BTEX mixture. Therefore, the raw petroleum refinery effluent might be a source of hydrocarbon-biodegrading microorganisms. 相似文献
980.
Fabrizio Quadrini Erica Anna Squeo Alessandro Guglielmotti 《Polymer Engineering and Science》2010,50(12):2431-2439
An experimental setup is proposed to perform creep indentation tests on thermoplastics. An infrared (IR) lamp is used to locally heat the sample, and a flat punch made of tungsten carbide is loaded on the sample surface. In order to show the capability of this test in evaluating the creep properties, creep indentation tests were carried out on PA66 and HDPE sheets at different temperatures and creep loads. Dynamic mechanical analyses (DMA) and uniaxial creep tests were also performed at different temperatures to have a comparison with the indentation test results. Master curves were built for all the test results, and time shift factors were extracted. In all cases, the logarithm values of the shift factor were linearly dependent on the temperature. Small differences were found in the shift factors of the DMA and uniaxial test results, whereas high differences were observed in the case of the indentation results due to the nonuniformity of the temperature in the sample. However, indentation creep compliance is strictly correlated with tensile creep compliance, and equivalent tensile creep properties can be extracted. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers 相似文献