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排序方式: 共有177条查询结果,搜索用时 46 毫秒
1.
The Fusion program, a method for agile, flexible computer integrated manufacturing (CIM) at Motorola's Paging Products Group, is discussed. Fusion's CIM and automated assembly system can manufacture a wide variety of different products on the same production line. The development of the Fusion program and how it differs from its predecessor, the Bandit program, are described 相似文献
2.
Cytochromes P450 2B metabolize a variety of compounds and have provided an excellent framework for identifying determinants of substrate specificity. Among the rat 2B enzymes, a puzzling difference has emerged between the reported substrate specificity of purified hepatic 2B2 and that of certain 2B1 mutants containing 2B1 --> 2B2 substitutions. To address these discrepancies, we have characterized two 2B2 variants. A cDNA clone designated 2B2FF was obtained from phenobarbital-induced Lewis rats and, like some previously isolated variants, was found to contain phenylalanine at positions 58 and 114. A second 2B2 clone was generated by restoring Leu and Ile, respectively, at these positions. These enzymes were expressed in Escherichia coli and analyzed with androstenedione, testosterone, progesterone, ethoxycoumarin, benzyloxyresorufin, and pentoxyresorufin. The expressed 2B2 variants metabolized most substrates at rates that were 1-9% of those of 2B1. When steroid regio- and stereospecificity was examined, the metabolite profiles of expressed 2B2 and 2B2FF conflicted with the 16beta- and 16alpha-hydroxylation observed for purified hepatic 2B2 from Sprague-Dawley rats. These and other results suggested that the purified hepatic 2B2 contained a small percent of the 2B1 enzyme. Masses of tryptic peptides were consistent with identity between purified hepatic 2B2 and 2B2FF. On the basis of a three-dimensional homology model and the construction and analysis of 2B2 mutants, residues 114, 363, 367, and 478 were identified as determinants of substrate specificity. In addition, 2B1 and the expressed 2B2 variants showed differential susceptibility to the mechanism-based inactivators chloramphenicol and N-(2-p-nitrophenethyl)chlorofluoroacetamide. 相似文献
3.
RS Strobel AK Nagy AF Knowles J Buegel MD Rosenberg 《Canadian Metallurgical Quarterly》1996,271(27):16323-16331
An ecto-ATP diphosphohydrolase (ATPDase) was purified to homogeneity from vesiculosomes shed from chicken oviduct. First, the ecto-ATPDase-enriched vesiculosomes were concentrated by filtration, differential centrifugation, and exclusion chromatography. Next, the nonionic detergent, Nonidet P-40, was used to extract the ecto-ATPDase from vesiculosomal membranes, and the solubilized enzyme was further purified by ion exchange (DEAE-Bio-Gel) and lentil-lectin-Sepharose 4B chromatography. In the final stage, immunoaffinity chromatography was utilized to obtain purified ecto-ATPDase. More than 25,000-fold purification was achieved. Specific activity of the purified enzyme was greater than 800 micronol/min/mg of protein with MgATP as the substrate, the highest ever reported for an ATPDase. The enzyme also hydrolyzed other nucleoside triphosphates in the presence of magnesium at similar rates and CaATP and MgADP at lower rates. The molecular mass of the purified glycoprotein was 80 kDa as determined by SDS-polyacrylamide gel electrophoresis and Western blot analysis. Based on its enzymatic properties, the relationship of the chicken oviduct ecto-ATPDase with other reported ATPDases and ecto-ATPases is discussed. 相似文献
4.
The functional groups responsible for branch site identity in the two steps of pre-mRNA splicing as well as for spliceosome assembly were tested by incorporation of site-specific modifications at the branch site of a pre-mRNA. These results show that recognition of the adenosine occurs early in complex formation and that the branch site adenosine is recognized differently before the first step and for the second step. Further, direct UV cross-linking with these modified RNAs was used to identify a factor whose interaction was dependent upon the identity of the branch site nucleotide. 相似文献
5.
6.
Pierre Strobel Jean-Claude Joubert Maria-Jesus Rodriguez 《Journal of Materials Science》1986,21(2):583-590
Single-crystal electron diffraction patterns were obtained on five specimens of -MnO2: one natural, two electrolytical (EMD) and two chemical (CMD) samples. EMDs are best described by the orthorhombic structure proposed by De Wolff which is derived from the ramsdellite structure. A CMD prepared from MnCO3 fits the hexagonal cell of -MnO2. Flaky grains from the natural sample and fibres from a CMD prepared from Mn(NO3)2 are hexagonal with a new cell:a 0.494,c 0.539 nm. No simple relation between chemical composition, morphology and structure could be found. 相似文献
7.
Dr. Eric J. Strobel 《Chembiochem : a European journal of chemical biology》2021,22(22):3214-3224
Site-specific strategies for exchanging segments of dsDNA are important for DNA library construction and molecular tagging. Deoxyuridine (dU) excision is an approach for generating 3’ ssDNA overhangs in gene assembly and molecular cloning procedures. Unlike approaches that use a multi-base pair motif to specify a DNA cut site, dU excision requires only a dT→dU substitution. Consequently, excision sites can be embedded in biologically active DNA sequences by placing dU substitutions at non-perturbative positions. In this work, I describe a molecular tagging method that uses dU excision to exchange a segment of a dsDNA strand with a long synthetic oligonucleotide. The core workflow of this method, called deoxyUridine eXcision-tagging (dUX-tagging), is an efficient one-pot reaction: strategically positioned dU nucleotides are excised from dsDNA to generate a 3’ overhang so that additional sequence can be appended by annealing and ligating a tagging oligonucleotide. The tagged DNA is then processed by one of two procedures to fill the 5’ overhang and remove excess tagging oligo. To facilitate its widespread use, all dUX-tagging procedures exclusively use commercially available reagents. As a result, dUX-tagging is a concise and easily implemented approach for high-efficiency linear dsDNA tagging. 相似文献
8.
Mirja Fa?bender Susann Minkwitz Catrin Strobel Gerhard Schmidmaier Britt Wildemann 《International journal of molecular sciences》2014,15(5):8539-8552
The aim of the study was to investigate the effect of a sustained release of bone morphogenetic protein2 (BMP-2) incorporated in a polymeric implant coating on bone healing. In vitro analysis revealed a sustained, but incomplete BMP-2 release until Day 42. For the in vivo study, the rat tibia osteotomy was stabilized either with control or BMP-2 coated wires, and the healing progress was followed by micro computed tomography (μCT), biomechanical testing and histology at Days 10, 28, 42 and 84. MicroCT showed an accelerated formation of mineralized callus, as well as remodeling and an increase of mineralized/total callus volume (p = 0.021) at Day 42 in the BMP-2 group compared to the control. Histology revealed an increased callus mineralization at Days 42 and 84 (p = 0.006) with reduced cartilage at Day 84 (p = 0.004) in the BMP-2 group. Biomechanical stiffness was significantly higher in the BMP-2 group (p = 0.045) at Day 42. In summary, bone healing was enhanced after sustained BMP-2 application compared to the control. Using the same drug delivery system, but a burst release of BMP-2, a previous published study showed a similar positive effect on bone healing. Distinct differences in the healing outcome might be explained due to the different BMP release kinetics and dosages. However, further studies are necessary to adapt the optimal release profiles to physiological mechanisms. 相似文献
9.
Mario Lhr Wolfgang Hrtig Almut Schulze Matthias Kroiß Silviu Sbiera Constantin Lapa Bianca Mages Sabrina Strobel Jennifer Elisabeth Hundt Simone Bohnert Stefan Kircher Sudha Janaki-Raman Camelia-Maria Monoranu 《International journal of molecular sciences》2022,23(7)
Targeting molecular alterations as an effective treatment for isocitrate dehydrogenase-wildtype glioblastoma (GBM) patients has not yet been established. Sterol-O-Acyl Transferase 1 (SOAT1), a key enzyme in the conversion of endoplasmic reticulum cholesterol to esters for storage in lipid droplets (LD), serves as a target for the orphan drug mitotane to treat adrenocortical carcinoma. Inhibition of SOAT1 also suppresses GBM growth. Here, we refined SOAT1-expression in GBM and IDH-mutant astrocytoma, CNS WHO grade 4 (HGA), and assessed the distribution of LD in these tumors. Twenty-seven GBM and three HGA specimens were evaluated by multiple GFAP, Iba1, IDH1 R132H, and SOAT1 immunofluorescence labeling as well as Oil Red O staining. To a small extent SOAT1 was expressed by tumor cells in both tumor entities. In contrast, strong expression was observed in glioma-associated macrophages. Triple immunofluorescence labeling revealed, for the first time, evidence for SOAT1 colocalization with Iba1 and IDH1 R132H, respectively. Furthermore, a notable difference in the amount of LD between GBM and HGA was observed. Therefore, SOAT1 suppression might be a therapeutic option to target GBM and HGA growth and invasiveness. In addition, the high expression in cells related to neuroinflammation could be beneficial for a concomitant suppression of protumoral microglia/macrophages. 相似文献
10.
Economic and process engineering advantages of extrusion cooking in comparison with conventional processes in the food industry . Extrusion cooking is introduced as a modern high-temperature short-time process. Possible process steps in extruder machine systems, such as continuous conveying, mixing, homogenizing and reactions, mechanical and thermal energy dissipation for plasticizing and modifying biopolymers, are explained. This process creates new products with completely new textures, for example in the snack and breakfast cereal sector, while on the other hand the extrusion process competes with long-standing conventional processes. The latter work slowly with low pressures, low temperatures and energy dissipation with high water contents in large batch-operated machines. The quality of extruder-cooked products depends on the extrusion system. The self-cleaning corotating twin-screw extruder with its narrow residence time spectrum is the optimum system. However, the counter-rotating intermeshing machine has certain advantages for products of low viscosity. The cooking time at high temperature is a matter of seconds, which serves to maintain the properties of the ingredients and active substances, while ensuring fast destruction of microorganisms. The end-products have a long shelf-life on account of their low process moisture content. Continuous extrusion cooking has economic advantages mainly because it replaces many batch processes and because extrusion is carried out entirely or almost entirely with the final moisture content, thus avoiding the necessity to evaporate huge quantities of water. 相似文献