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排序方式: 共有376条查询结果,搜索用时 31 毫秒
31.
M Wolfersdorf RD Stieglitz R Metzger A Ruppe S Stabenow C Hornstein F Keller G Schell M Berger 《Canadian Metallurgical Quarterly》1997,24(3):120-128
An apparent species-specific relatedness of SIVagm suggests a coevolution with their natural hosts. However, the exact species or subspecies classification of African green monkeys, AGM, is uncertain because current classification schemes rely on phenotype markers, while more definitive genetic data are lacking. In this study, the CD4 protein involved in tissue type recognition was genetically cloned and sequenced from PBMC RNA from all AGM species, including Barbados green monkeys (BGM). Phylogenetic trees were constructed that also included genomic CD4 nucleotide sequences from patas, sooty mangabeys, rhesus and pig-tail macaques, chimpanzees, and humans. Chimpanzees and humans consistently clustered together. Monkeys within the Cercopithecus genus formed a separate cluster which included pata monkeys, supporting its grouping as a member of Cercopithecus. Surprisingly, sooty mangabeys were genetically more closely related to Asian macaques than to other African species, which might explain why macaques are more susceptible to infection by the SIVsm group than to infection by SIVagm or HIV-1 and why patas, on the other hand, are highly susceptible to SIVagm infection. Based on CD4 genetic data, tantalus, vervets, grivets, and sabaeus formed separate subgroups with BGM grouping closely with vervets. The branching order of the AGM species was related to that of their respective SIVagm env sequences. The study suggests a strong correlation between CD4 phylogeny and the susceptibility of the host species to infection by a specific lentivirus and supports the assumption of a coevolution of SIVagm and AGM. CD4 sequencing is suggested as a relevant method for genetic determination of primate species. 相似文献
32.
Commercially available, wide-pore ultrafiltration membranes were evaluated for production of α-lactalbumin (α-LA)-enriched whey protein concentrate (WPC). In this study microfiltration was used to produce a prepurified feed that was devoid of casein fines, lipid materials, and aggregated proteins. This prepurified feed was subsequently subjected to a wide-pore ultrafiltration process that produced an α-LA-enriched fraction in the permeate. We evaluated the performance of 3 membrane types and a range of transmembrane pressures. We determined that the optimal process used a polyvinylidene fluoride membrane (molecular weight cut-off of 50 kDa) operated at transmembrane pressure (TMP) of 207 kPa. This membrane type and operating pressure resulted in α-LA purity of 0.63, α-LA:β-LG ratio of 1.41, α-LA yield of 21.27%, and overall flux of 49.46 L/m2·h. The manufacturing cost of the process for a hypothetical plant indicated that α-LA-enriched WPC 80 (i.e., with 80% protein) could be produced at $17.92/kg when the price of whey was considered as an input cost. This price came down to $16.46/kg when the price of whey was not considered as an input cost. The results of this study indicate that production of a commercially viable α-LA-enriched WPC is possible and the process developed can be used to meet worldwide demand for α-LA-enriched whey protein. 相似文献
33.
HP Fiedler M Nega C Pfefferle I Groth C Kempter H Stephan JW Metzger 《Canadian Metallurgical Quarterly》1996,49(8):758-764
The kanchanamycins, a group of novel 36-membered polyol macrolide antibiotics were detected in the culture filtrate and mycelium of Streptomyces olivaceus Tü 4018 by HPLC-diode-array and HPLC-electrospray-mass-spectrometry screening. The compounds show antibacterial and antifungal activities, and are especially effective against Pseudomonas fluorescens. Besides the kanchanamycin complex, strain Tü 4018 produces the 42-membered macrolactones, oasomycin A and desertomycin A, as well as tryptophan-dehydrobutyrine diketopiperazine and daidzein. 相似文献
34.
Rats were given suction lesions of the presumptive frontal cortex on embryonic day 18 (E18) and subsequently tested, as adults, on tests of spatial navigation (Morris water task, radial arm maze), motor tasks (Whishaw reaching task, beam walking), and locomotor activity. Frontal cortical lesions at E18 affected cerebral morphogenesis, producing unusual morphological structures including abnormal patches of neurons in the cortex and white matter as well as neuronal bridges between the hemispheres. A small sample of E18 operates also had hydrocephaly. The animals with E18 lesions without hydrocephalus were behaviorally indistinguishable from littermate controls. The results demonstrate that animals with focal lesions of the presumptive frontal cortex have gross abnormalities in cerebral morphology but the lesions leave the functions normally subserved by the frontal cortex in adult rats unaffected. The results are discussed in the context of a hypothesis regarding the optimal times for functional recovery from cortical injury. 相似文献
35.
36.
RJ McNally LJ Metzger NB Lasko SA Clancy RK Pitman 《Canadian Metallurgical Quarterly》1998,107(4):596-601
The authors used a directed-forgetting task to investigate whether psychiatrically impaired adult survivors of childhood sexual abuse exhibit an avoidant encoding style and impaired memory for trauma cues. The authors tested women with abuse histories, either with or without posttraumatic stress disorder (PTSD), and women with neither abuse histories nor PTSD. The women saw intermixed trauma words (e.g., molested), positive words (e.g., confident), and categorized neutral words (e.g., mailbox) on a computer screen and were instructed either to remember or to forget each word. Relative to the other groups, the PTSD group did not exhibit recall deficits for trauma-related to-be-remembered words, nor did they recall fewer trauma-related to-be-forgotten words than other words. Instead, they exhibited recall deficits for positive and neutral words they were supposed to remember. These data are inconsistent with the hypothesis that impaired survivors exhibit avoidant encoding and impaired memory for traumatic information. 相似文献
37.
Porcine colipase, the protein cofactor of pancreatic lipase, was isolated from pancreas freshly collected on animals and from a side fraction from the production of insulin (Novo Nordisk A/S). Samples of purified colipase were analyzed for homogeneity by polyacrylamide gel electrophoresis, reverse-phase high-performance liquid chromatography (RPLC), quantitative N-terminal sequence determination and mass spectrometry. The activating properties of colipase preparations were assayed against tributyrin, triolein or the commercial Intralipid emulsion, in presence of bile salt. Two fractions of colipase with the same specific activity were purified from fresh pancreas. The major fraction (85%) contained one single protein corresponding to fragment 1-93 of the 95-residue form of colipase (procolipase) previously characterized in porcine pancreatic juice. The other fraction (15%) corresponded to fragment 1-91 of procolipase. Also, two fractions of colipase were purified from the side fraction supplied by Novo. These fractions consisted of the 95-residue proform of colipase and of fragment 1-93, respectively, both specifically cleaved at the Ile79-Thr80 peptide bond with partial removal of isoleucine at position 79 and serine at position 78. Procolipase split at the 79-80 bond retained full activity on tributyrin and triolein and on the Intralipid emulsion but the kinetics of hydrolysis of triacylglycerol substrates showed much longer lag periods than those observed with native procolipase. Also, all forms of procolipase split at the 79-80 bond showed one peak in RPLC but their retention time was markedly decreased as compared to that of native procolipase which indicated a weaker hydrophobic binding capacity. The value of the retention time was of the same order of magnitude as that of inactive reduced procolipase. Treatment of native procolipase by pancreatic endopeptidases showed that elastase is likely responsible for specific cleavage at the 79-80 bond of procolipase purified from the Novo extract. Limited proteolysis by trypsin of the proforms of colipase split at the 79-80 bond reduced the lag period. Results presented in this communication provide the first direct evidence showing that the finger-shaped peptide segment between half-cystine residues at positions 69 and 87 is involved in colipase-lipid interaction as previously hypothesized from the three-dimensional structure of the protein. 相似文献
38.
SL Brody M Metzger C Danel MA Rosenfeld RG Crystal 《Canadian Metallurgical Quarterly》1994,5(7):821-836
Recombinant human adenovirus (Ad) vectors are leading candidates for human gene therapy for cystic fibrosis (CF) based on demonstration of efficient transfer of exogenous genes to rodent respiratory epithelium in vivo and human respiratory cells in vitro. The safety of Ad-mediated gene transfer to the respiratory epithelium and acute (up to 21 days) clinical responses to airway delivery of a replication-deficient recombinant, E1-, E3- Ad type 5-based vector containing the human cystic fibrosis transmembrane conductance regulator cDNA (AdCFTR) were evaluated in rhesus monkeys. Airway delivery of an Ad vector with the lacZ marker gene demonstrated beta-galactosidase expression in epithelial cells. Animals administered intratracheal AdCFTR demonstrated human CFTR cDNA expression in airway epithelial cells. Animals administered AdCFTR intranasal, and 24 hr later, intrabronchial [2 x 10(7) to 5 x 10(10) plaque-forming units (pfu), n = 12], in a fashion similar to a proposed human protocol, or only intrabronchial (10(11) pfu, n = 3), had no significant changes in clinical parameters compared to vehicle controls (n = 6). Microscopic analysis of the lung by necropsy or bronchoalveolar lavage demonstrated a dose-dependent increase in inflammatory cells, primarily lymphocytes, in the area where AdCFTR was delivered, which persisted for at least 2 months in some animals. Serum anti-Ad type 5 neutralizing antibody titers did not rise and shed Ad was not detected. The presence of AdCFTR DNA, analyzed by the polymerase chain reaction (PCR), was not detected in organs outside the lung. These data demonstrate that AdCFTR is well tolerated in non-human primates, although there is dose-dependent inflammation in the lung not clinically apparent.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
39.
Auger and electron diffraction studies of Al2O3 isolated from a composite prepared by introducing fibers into a vigorously agitated Al−Mg melt indicated the presence of
MgAl2O4 on the fiber surface. The evidence suggested that the spinel was present as discrete crystals. The thickness and coverage
of the spinel is likely to vary with processing conditions.
R. MEHRABIAN formerly with the University of Illinois 相似文献
40.
Peripheral blood lymphocytes from two human donors with elevated serum IgE concentrations were maintained in short term tissue culture preparations. Repeated culture preparations demonstrated that IgE was produced in vitro in amounts that could be measured by the double antibody radioimmunoassay technique. The amount of IgE produced by replicate cultures of cells from a single bleeding of the donor was similar when the cultures were simultaneously prepared. In contrast, IgE production by the same donor's lymphocytes varied when the culture preparations were initiated from separate bleedings. The results of simultaneous cultures of a single bleeding were sufficiently consistent to provide a means of testing the effect of pharmacologic agents on the in vitro production of IgE. Cholera toxin effected a marked reduction in production of IgE by lymphocytes of both cell donors. Isoproterenol showed marked inhibition of IgE production at 10(-3) M but cell viability studies suggested that this may have been due to decreased cell viability. At lower, nontoxic concentrations of isoproterenol (10(-4) M-10(-6) M) slight but definite inhibition of in vitro IgE production was evident. This inhibition was more pronounced subsequent to the first 24 hr of exposure of the cells to isoproterenol. 相似文献