全文获取类型
收费全文 | 429篇 |
免费 | 9篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 72篇 |
金属工艺 | 3篇 |
机械仪表 | 13篇 |
建筑科学 | 7篇 |
能源动力 | 7篇 |
轻工业 | 32篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 21篇 |
一般工业技术 | 116篇 |
冶金工业 | 119篇 |
原子能技术 | 7篇 |
自动化技术 | 35篇 |
出版年
2020年 | 6篇 |
2019年 | 6篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 13篇 |
2010年 | 5篇 |
2009年 | 16篇 |
2008年 | 17篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 39篇 |
1997年 | 25篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1964年 | 4篇 |
1927年 | 2篇 |
排序方式: 共有438条查询结果,搜索用时 31 毫秒
61.
62.
James K. Knowles 《Engineering Fracture Mechanics》1981,15(3-4):469-476
A recent result of Stephenson[1] shows that, when finite deformations are taken into account, a crack under Mode II loading conditions in plane strain will open, at least near the crack-tip and at least for certain elastic materials. In this note, the matter is investigated further, and it is shown that, in general, nonlinear effects—even at small loads—lead either to crack-opening or apparent interpenetration of the crack-faces when the loading is of Mode II-type. 相似文献
63.
64.
MA Reynolds RI Hogrefe JA Jaeger DA Schwartz TA Riley WB Marvin WJ Daily MM Vaghefi TA Beck SK Knowles RE Klem LJ Arnold 《Canadian Metallurgical Quarterly》1996,24(22):4584-4591
Methylphosphonate (MP) oligodeoxynucleotides (MPOs) are metabolically stable analogs of conventional DNA containing a methyl group in place of one of the non-bonding phosphoryl oxygens. All 16 possible chiral R(P) MP dinucleotides were synthesized and derivatized for automated oligonucleotide synthesis. These dimer synthons can be used to prepare (i) all-MP linked oligonucleotides having defined R(P) chirality at every other position (R(P) chirally enriched MPOs) or (ii) alternating R(P) MP/phosphodiester backbone oligonucleotides, depending on the composition of the 3'-coupling group. Chirally pure dimer synthons were also prepared with 2'-O-methyl sugar modifications. Oligonucleotides prepared with these R(P) chiral methylphosphonate linkage synthons bind RNA with significantly higher affinity than racemic MPOs. 相似文献
65.
A technique is described which enables a pulsed transfer function with complex poles and zeros to be cascade-programmed. Owing to the finite wordlength of the computer, computational errors arise when the realisation is used to process information. These can be represented in the steady state by a set of spurious error sequences additively contaminating the output of an ideal realisation. The shaping filters relating these error sequences to simple roundoff errors are derived. 相似文献
66.
Robert M. Moss David M. Pickup Ifty Ahmed Jonathan C. Knowles Mark E. Smith Robert J. Newport 《Advanced functional materials》2008,18(4):634-639
Neutron diffraction with isotopic substitution has been used to probe the local environment of silver in a melt‐quench derived bioresorbable phosphate glass. Samples enriched with 107Ag and 109Ag were prepared and neutron diffraction data collected. A first‐order difference was taken between the data sets to give detailed information about the silver environment in the glass matrix. The measured Ag‐O correlation has three components in the first coordination shell at 2.28 Å, 2.51 Å, and 2.58 Å with coordination numbers of 2.1, 2.7, and 1.1, respectively, consistent with silver occupying a distorted octahedral environment. These results have been correlated with those from Ag K‐edge X‐ray absorption near‐edge spectroscopy measurements. The results suggest that the addition of silver to the (CaO)0.3(Na2O)0.2(P2O5)0.5 system has a significant effect on the host phosphate network, with shorter and more branched chains replacing the long chains and rings normally associated with the metaphosphate composition. 相似文献
67.
Sabeel P. Valappil Derren Ready Ensanya A. Abou Neel David M. Pickup Wojciech Chrzanowski Luke A. O'Dell Robert J. Newport Mark E. Smith Michael Wilson Jonathan C. Knowles 《Advanced functional materials》2008,18(5):732-741
Novel quaternary gallium‐doped phosphate‐based glasses (1, 3, and 5 mol % Ga2O3) were synthesized using a conventional melt quenching technique. The bactericidal activities of the glasses were tested against both Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) and Gram‐positive (Staphylococcus aureus, methicillin‐resistant Staphylococcus aureus, and Clostridium difficile) bacteria. Results of the solubility and ion release studies showed that these glass systems are unique for controlled delivery of Ga3+. 71Ga NMR measurements showed that the gallium is mostly octahedrally coordinated by oxygen atoms, whilst FTIR spectroscopy provided evidence for the presence of a small proportion of tetrahedral gallium in the samples with the highest gallium content. FTIR and Raman spectra also afford an insight into the correlation between the structure and the observed dissolution behavior via an understanding of the atomic‐scale network bonding characteristics. The results confirmed that the net bactericidal effect was due to Ga3+, and a concentration as low as 1 mol % Ga2O3 was sufficient to mount a potent antibacterial effect. The dearth of new antibiotics in development makes Ga3+ a potentially promising new therapeutic agent for pathogenic bacteria including MRSA and C. difficile. 相似文献
68.
Ensanya A. Abou Neel Azadeh Kiani Sabeel P. Valappil Nicky M. Mordan Song-Yi Baek Kazi M. Zakir Hossain Reda M. Felfel Ifty Ahmed Kamini Divakarl Wojciech Chrzanowski Jonathan C. Knowles 《应用聚合物科学杂志》2019,136(32):47832
This study aimed to formulate antibacterial dental adhesives. Phosphate-substituted methacrylate adhesives were modified with 0–20 wt % copper-doped glass microparticles. Two shapes of microparticles were used: regular shaped (microspheres) and irregular shaped (microparticles). The morphology/composition, roughness, monomer conversion (DC%), thermogravimetric analysis, and antibacterial action against S. mutans and P. aeruginosa and ion release were investigated. The results showed that microspheres produced adhesives with a relatively smoother surface than microparticles did. The DC% of adhesives increased with increasing glass filler content. Filled adhesives showed polymer decomposition at ~315 °C and glass melting at 600–1000 °C. The weight loss percent of adhesives decreased with increasing weight percent of fillers. Glass microparticles at 0–20 wt % significantly increased the antibacterial action of adhesives against both bacteria. Glass microspheres at 0–5 wt % significantly increased the antibacterial action of adhesives against both bacteria. Only 20 wt % microparticle-filled adhesive showed an inhibition zone similar to tobramycin (positive control). Microparticle-filled adhesives (with >5 wt % filler) significantly reduced S. mutans more than their microsphere counterparts. Microsphere-filled adhesives (with ≤5 wt % filler) significantly reduced P. aeruginosa more than their microparticle counterparts. Microsphere-filled adhesives showed higher Cu release than their microparticle counterparts. Accordingly, phosphate-substituted methacrylate filled with glass could be used as an antibacterial adhesive. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47832. 相似文献
69.
M Macek A Mackova A Hamosh BC Hilman RF Selden G Lucotte KJ Friedman MR Knowles BJ Rosenstein GR Cutting 《Canadian Metallurgical Quarterly》1997,60(5):1122-1127
Cystic fibrosis (CF)--an autosomal recessive disorder caused by mutations in CF transmembrane conductance regulator (CFTR) and characterized by abnormal chloride conduction across epithelial membranes, leading to chronic lung and exocrine pancreatic disease--is less common in African-Americans than in Caucasians. No large-scale studies of mutation identification and screening in African-American CF patients have been reported, to date. In this study, the entire coding and flanking intronic sequence of the CFTR gene was analyzed by denaturing gradient-gel electrophoresis and sequencing in an index group of 82 African-American CF chromosomes to identify mutations. One novel mutation, 3120+1G-->A, occurred with a frequency of 12.3% and was also detected in a native African patient. To establish frequencies, an additional group of 66 African-American CF chromosomes were screened for mutations identified in two or more African-American patients. Screening for 16 "common Caucasian" mutations identified 52% of CF alleles in African-Americans, while screening for 8 "common African" mutations accounted for an additional 23%. The combined detection rate of 75% was comparable to the sensitivity of mutation analysis in Caucasian CF patients. These results indicate that African-Americans have their own set of "common" CF mutations that originate from the native African population. Inclusion of these "common" mutations substantially improves CF mutation detection rates in African-Americans. 相似文献
70.
Tommaso Marchesi D'Alvise Sean Harvey Lisa Hueske Jolanta Szelwicka Lothar Veith Tuomas P. J. Knowles Dennis Kubiczek Carolin Flaig Fabian Port Kay‐E. Gottschalk Frank Rosenau Bartlomiej Graczykowski George Fytas Francesco S. Ruggeri Katrin Wunderlich Tanja Weil 《Advanced functional materials》2020,30(21)
Cellular membranes have long served as an inspiration for nanomaterial research. The preparation of ultrathin polydopamine (PDA) films with integrated protein pores containing phospholipids and an embedded domain of a membrane protein glycophorin A as simplified cell membrane mimics is reported. Large area, ultrathin PDA films are obtained by electropolymerization on gold surfaces with 10–18 nm thickness and dimensions of up to 2.5 cm2. The films are transferred from gold to various other substrates such as nylon mesh, silicon, or substrates containing holes in the micrometer range, and they remain intact even after transfer. The novel transfer technique gives access to freestanding PDA films that remain stable even at the air interfaces with elastic moduli of ≈6–12 GPa, which are higher than any other PDA films reported before. As the PDA film thickness is within the range of cellular membranes, monodisperse protein nanopores, so‐called “nanodiscs,” are integrated as functional entities. These nanodisc‐containing PDA films can serve as semi‐permeable films, in which the embedded pores control material transport. In the future, these simplified cell membrane mimics may offer structural investigations of the embedded membrane proteins to receive an improved understanding of protein‐mediated transport processes in cellular membranes. 相似文献