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排序方式: 共有233条查询结果,搜索用时 15 毫秒
81.
Vibeke Andersen Tine Iskov Kopp Anne Tj?nneland Ulla Vogel 《International journal of molecular sciences》2015,16(1):1375-1384
Red meat is a risk factor for colorectal cancer (CRC). We wanted to evaluate whether a functional polymorphism in the HMOX1 gene encoding heme oxygenase modifies risk of CRC or interacts with diet or lifestyle factors because this would identify heme or heme iron as a risk factor of CRC. The HMOX1 A-413T (rs2071746) was assessed in relation to risk of colorectal cancer (CRC) and interactions with diet (red meat, fish, fiber, cereals, fruit and vegetables) and lifestyle (use of non-steroidal anti-inflammatory drug and smoking status) were assessed in a case-cohort study of 928 CRC cases and a comparison group of 1726 randomly selected participants from a prospective study of 57,053 persons. No association between HMOX1 A-413T and CRC risk was found (TT vs. AA + TA; IRR = 1.15, 95% CI: 0.98–1.36, p = 0.10 for the adjusted estimate). No interactions were found between diet or lifestyle and HMOX1 A-413T. HMOX1 A-413T was not associated with CRC risk and no interactions with diet or lifestyle were identified in this large, prospective cohort with high meat intake. The results reproduced the previous findings from the same cohort and did not support a link between heme or heme iron and colorectal cancer. These results should be sought and replicated in other well-characterized cohorts with high meat intake. 相似文献
82.
Photolytic debromination of decabromodiphenyl ether (BDE 209) 总被引:8,自引:0,他引:8
Söderstrom G Sellström U de Wit CA Tysklind M 《Environmental science & technology》2004,38(1):127-132
Polybrominated diphenyl ethers (PBDE) are commonly used flame retardants. During the past years, concerns have increased due to their occurrence in the environment and humans. In general, the concentrations of lower brominated (tetra-penta) diphenyl ethers in biota exceed those of the most heavily used product, decabromodiphenyl ether (DecaBDE). In this study, the photolytic debromination of DecaBDE has been investigated in order to study the formation of lower brominated diphenyl ethers. The time course of photolysis of DecaBDE was studied in toluene, on silica gel, sand, sediment and soil using artificial sunlight and on the natural matrices (sediment, soil, sand) also using natural sunlight. DecaBDE was photolytically labile and formed debromination products in all matrices studied. Nona- to tetraBDEs were formed as well as some PBDFs. The half-lives in toluene and on silica gel were less than 15 min, and half-lives on other matrices ranged between 40 and 200 h. No differences were seen in the debromination pattern of BDE congeners sequentially formed in the different matrices or under different light conditions. However, the debromination rates were strongly dependent on the matrix with longer half-lives on natural matrices than artificial ones. 相似文献
83.
Vinther TN Ribel U Pedersen TA Kjeldsen TB Jensen KJ Hubálek F 《Chembiochem : a European journal of chemical biology》2011,12(16):2448-2455
Chemical modifications of proteins are increasingly important in the development of protein drugs with fine-tuned properties. Regioselective modification, such as the chemoselective alkylation of an unpaired cysteine residue, is a prerequisite for obtaining homogenous protein products. The introduction of an unpaired Cys into the Cys-rich protein, insulin, was investigated by using a Cys scan. This was challenging as the introduced Cys could interfere with insulin's three existing disulfide bonds. However, eight insulin precursors were expressed in Saccharomyces cerevisiae with good yields. Although extensive post-translational modifications of the unpaired Cys were observed, the majority could be removed by selective reduction. An example Cys(7) insulin analogue was modified with a PEGylated maleimide moiety. The new variant was active in in vitro and in vivo models. Our results show that even small Cys-rich proteins can be expressed with additional unpaired Cys in meaningful yields and further chemically modified, while maintaining their biological activity. 相似文献
84.
Grete Brunsgaard Ulla Kidmose K Kaack B O Eggum 《Journal of the science of food and agriculture》1994,65(3):363-370
Green peas (Pisum sativum L) were harvested at three different time points—3 days apart—and subsequently sorted into four fractions according to seed size (diameter > 10.2 mm; 10.2–8.75 mm; 8.75–8.2 mm and 8.2–6.0 mm). Three varieties from two years were investigated. The study comprised a total of 31 green pea samples. The average protein content of the samples was 276 g kg?1 DM with relatively low variation (SE = 5.7). Protein content was highest in the smallest seeds. The average energy content was 18.6 MJ kg?1DM. Dietary fibre content was 226 g kg?1 DM, the major part (77%) as insoluble fibre. Seeds of early harvest and seeds with the smallest diameter had the lowest fibre (IDF and TDF) content and at the same time the highest energy digestibility. The average energy digestibility was 83.2%. Protein digestibility was relatively high (average 92.1%), while biological value (BV) and net protein utilisation (NPU) were moderate to low (60.6% and 55.8% respectively) due to low contents of the essential amino acids (g per 16 g N), especially tryptophan, methionine + cystine and lysine. Contents of lysine, tryptophan and methionine + cystine were more than 20% higher in the smallest seeds compared to the larger seeds. Similar differences were observed in seeds of late harvest as compared with seeds of early harvest. Correlation coefficients revealed a strong positive correlation between lysine, tryptophan and methionine + cystine content and the biological value of green pea protein. The three varieties investigated showed no differences in the chemical parameters although small differences in BV and NPU were observed. 相似文献
85.
Werner Heimann Ulla Timm Adolf Rapp und Werner Knipser 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1980,171(1):35-37
Zusammenfassung Es wurden die durch Sojamehlzusatz bei Mürbeteiggebäck hervorgerufenen Veränderungen der Aromastoffzusammensetzung untersucht. Diejenigen flüchtigen Aromastoffe, die bei sonst identischer Peakabfolge für die quantitativen Unterschiede in den Aromagrammen von normalem und soja-angereichertem Gebäck verantwortlich sind, wurden erfaßt und mittels kombinierter Gaschromatographie/Massenspektrometrie größtenteils identifiziert. Es handelte sich um die Substanzen 1-Hexanol, Dimethylpyrazin, 2,3,5-Trimethylpyrazin, Furfural, Benzaldehyd,-3-Phenyläthanol, 2-Methyl-3-hydroxypyron, 2-Formylpyrrol und 4-Vinylguajakol.Da diese Substanzen — mit Ausnahme von 1-Hexanol und Benzaldehyd — mengenmäßig nicht aromabestimmend im Sojateig hervortraten, muß ihre höhere Konzentration im sofa-angereicherten Gebäck auf Reaktionen während des Backprozesses zurückgeführt werden.
Herrn Professor Dr. Ulrich Freimuth zum 65. Geburtstag gewidmet 相似文献
Changes of flavor compounds caused by addition of soyflour to short pastryII. Investigations in biscuits
Summary The changes of flavor compounds caused by addition of soy flour to short pastry were investigated. The volatile flavor compounds were isolated and most of them identified by combined gas-chromatographic-mass-spectral-analysis; they are responsible for the quantitative differences between the aromagrams of usual and soy-fortified pastry. These flavor compounds were 1-hexanol, dimethylpyrazine, 2,3,5-trimethylpyrazine, furfural, benzaldehyde-phenyl-lethanol, 2-methyl-3-hydroxypyrone, 2-formylpyrrole, and 4-vinylguajacol. The importance of the soyflour during the baking process on the development of these flavor compounds is discussed.
Herrn Professor Dr. Ulrich Freimuth zum 65. Geburtstag gewidmet 相似文献
86.
Coffee shows distinct antimicrobial activity against several bacterial genera. The present study investigated molecular mechanisms and active ingredients mediating the antimicrobial effect of coffee. Depending on concentration, roasted, but not raw coffee brew inhibited the growth of Escherichia coli and Listeria innocua. Several coffee ingredients with known antibacterial properties were tested for their contribution to the observed effect. In natural concentration, caffeine, ferulic acid and a mixture of all test compounds showed very weak, but significant activity, whereas trigonelline, 5-(hydroxymethyl)furfural, chlorogenic acid, nicotinic acid, caffeic acid, and methylglyoxal were not active. Antimicrobial activity, however, was completely abolished by addition of catalase indicating that H(2)O(2) is a major antimicrobial coffee component. In accordance with this assumption, bacterial counts during 16 h of incubation were inversely related to the H(2)O(2) concentration in the incubation solution. Pure H(2)O(2) showed slightly weaker activity. The H(2)O(2) dependent antimicrobial activity of coffee could be mimicked by a reaction mixture of d-ribose and l-lysine (30 min 120 °C) indicating that H(2)O(2) is generated in the coffee brew by Maillard reaction products. Identification of H(2)O(2) as major antimicrobial coffee component is important to evaluate the application of coffee or coffee extracts as natural preservatives. 相似文献
87.
Ulla König Anja Lode Petra B. Welzel Yuichiro Ueda Sven Knaack Anja Henß Anke Hauswald Michael Gelinsky 《Journal of materials science. Materials in medicine》2014,25(3):607-621
This study intended to evaluate a contemporary concept of scaffolding in bone tissue engineering in order to mimic functions of the extracellular matrix. The investigated approach considered the effect of the glycosaminoglycan heparin on structural and biological properties of a synthetic biomimetic bone graft material consisting of mineralized collagen. Two strategies for heparin functionalization were explored in order to receive a three-component bone substitute material. Heparin was either incorporated during matrix synthesis by mixing with collagen prior to simultaneous fibril reassembly and mineralization (in situ) or added to the matrix after fabrication (a posteriori). Both methods resulted in an incorporation of comparable amounts of heparin, though its distribution in the matrix varied as indicated by TOF-SIMS analyses, and a similar modulation of their protein binding properties. Differential scanning calorimetry revealed that the thermal stability and thereby the degree of crosslinking of the heparinized matrices was increased. However, in contrast to the a posteriori modification, the in situ integration of heparin led to considerable changes of morphology and composition of the matrix: a more open network of collagen fibers yielding a more porous surface and a reduced mineral content were observed. Cell culture experiments with human mesenchymal stem cells (hMSC) revealed a strong influence of the mode of heparin functionalization on cellular processes, as demonstrated for proliferation and osteogenic differentiation of hMSC. Our results indicate that not only heparin per se but also the way of its incorporation into a collagenous matrix determines the cell response. In conclusion, the a posteriori modification was beneficial to support adhesion, proliferation and differentiation of hMSC. 相似文献
88.
89.
The well-known Ni cluster formation in solid solutions of CuNi around the 50:50 composition was formerly observed during thermal annealing down to temperatures of about 620 K, when the vacancy mobility practically vanishes. In the present work Ni cluster formation has been observed during electron irradiation at temperatures as low as 100 K. The required mass transport must be due to an interstitialcy mechanism. The activation energy of interstitial motion is of the order of 0.2 eV. From the observed cluster formation, kinetic details of the interaction of migrating interstitials with other lattice defects can be derived. 相似文献
90.
Karin S Hougaard Keld A Jensen Pernille Nordly Camilla Taxvig Ulla Vogel Anne T Saber Håkan Wallin 《Particle and fibre toxicology》2008,5(1):1-15