全文获取类型
收费全文 | 338篇 |
免费 | 22篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 5篇 |
综合类 | 18篇 |
化学工业 | 98篇 |
金属工艺 | 32篇 |
机械仪表 | 13篇 |
建筑科学 | 20篇 |
矿业工程 | 2篇 |
能源动力 | 5篇 |
轻工业 | 55篇 |
水利工程 | 2篇 |
石油天然气 | 21篇 |
武器工业 | 1篇 |
无线电 | 23篇 |
一般工业技术 | 26篇 |
冶金工业 | 9篇 |
原子能技术 | 2篇 |
自动化技术 | 39篇 |
出版年
2023年 | 4篇 |
2022年 | 12篇 |
2021年 | 21篇 |
2020年 | 4篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 14篇 |
2012年 | 16篇 |
2011年 | 24篇 |
2010年 | 21篇 |
2009年 | 23篇 |
2008年 | 28篇 |
2007年 | 25篇 |
2006年 | 17篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 15篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 12篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有371条查询结果,搜索用时 15 毫秒
361.
Masaaki Nakai Mitsuo Niinomi Toshikazu Akahori Naofumi Ohtsu Hideki Nishimura Hiroyuki Toda Hisao Fukui Michiharu Ogawa 《Materials Science and Engineering: A》2008,486(1-2):193-201
The microstructure and hardness near the surface of a biomedical titanium alloy, Ti–29Nb–13Ta–4.6Zr (TNTZ), subjected to gas nitriding at 1023–1223 K was investigated in comparison with the conventional biomedical Ti–6Al–4V ELI (Ti64). After gas nitriding, the microstructure near the specimen surface was observed by optical microscopy, X-ray diffraction (XRD), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). In both alloys, two types of titanium nitrides (TiN and Ti2N) are formed and the phase is precipitated by gas nitriding. Furthermore, the oxygen impurity in the gas nitriding atmosphere reacts with the titanium nitrides; thus, TiO2 is formed at the outermost titanium nitride layer. The surface hardening was also evaluated by Vickers hardness measurement. The Vickers hardness near the surface of TNTZ and Ti64 increases significantly by gas nitriding. 相似文献
362.
Abdolraouf Samadi-Maybodi Naser Goudarzi Christopher W. Kirby Yining Huang 《Journal of surfactants and detergents》2008,11(1):49-54
Silicate anions were studied using 29Si NMR to investigate the structure-directing effect of a surfactant (sodium dodecylsulfate-SDS) on the distribution of silicate
species present in alkaline silicate solutions. The distribution of the anions in the presence of polyelectrolytes was also
investigated by 29Si NMR through the use of different bases including tetramethyl ammonium hydroxide (TMAOH) and sodium hydroxide (NaOH). Both
SDS and the polyelectrolytic solutions were shown to stabilize low molecular weight silicate species and thus inhibit polymerization.
相似文献
Abdolraouf Samadi-MaybodiEmail: |
363.
Narasimha Kumar Kopparapu Zhuqing Liu Qiaojuan Yan Zhengqiang Jiang Shuping Zhang 《Food chemistry》2011
A novel chitinase was isolated and purified to its homogeneity from pomegranate juice by a combination of ammonium sulphate precipitation and ion-exchange chromatography. The pomegranate juice chitinase (PJC) was purified to specific activity of 14.5 U/mg and a recovery of 34%. The monomeric protein migrated on SDS–PAGE at 29 kDa. The enzyme was found to be glycosylated (7.2%). It exhibited optimal activity at pH 4.5 and 70 °C. The enzyme was stable in the pH range 3.0–9.0 and up to 65 °C. The internal peptide sequence results suggest that the purified PJC shared high homology with class III chitinases of other known plant chitinases. The purified enzyme could hydrolyse colloidal chitin to its oligomers. It did not exhibit any antifungal activity. 相似文献
364.
Carlos Ayala-Torres Susanne M. Krug Rita Rosenthal Michael Fromm 《International journal of molecular sciences》2021,22(15)
Water transport in epithelia occurs transcellularly (aquaporins) and paracellularly (claudin-2, claudin-15). Recently, we showed that downregulated tricellulin, a protein of the tricellular tight junction (tTJ, the site where three epithelial cells meet), increased transepithelial water flux. We now check the hypothesis that another tTJ-associated protein, angulin-1 (alias lipolysis-stimulated lipoprotein receptor, LSR) is a direct negative actuator of tTJ water permeability depending on the tightness of the epithelium. For this, a tight and an intermediate-tight epithelial cell line, MDCK C7 and HT-29/B6, were stably transfected with CRISPR/Cas9 and single-guide RNA targeting angulin-1 and morphologically and functionally characterized. Water flux induced by an osmotic gradient using 4-kDa dextran caused water flux to increase in angulin-1 KO clones in MDCK C7 cells, but not in HT-29/B6 cells. In addition, we found that water permeability in HT-29/B6 cells was not modified after either angulin-1 knockout or tricellulin knockdown, which may be related to the presence of other pathways, which reduce the impact of the tTJ pathway. In conclusion, modulation of the tTJ by knockout or knockdown of tTJ proteins affects ion and macromolecule permeability in tight and intermediate-tight epithelial cell lines, while the transepithelial water permeability was affected only in tight cell lines. 相似文献
365.
Milk fat globules were extracted from bovine and goat milk and incubated with HT-29 human adenocarcinoma cells to assess the attachment and internalization of Salmonella Enteritidis. Because the expression of bacterial adhesins is highly affected by the presence of antibiotic, the attachment was studied with and without antibiotic in the cell growth medium. Although no inhibitory effect of the fat globules was observed in the presence of the antibiotic, milk fat globules significantly inhibited the binding and internalization of Salmonella in medium free of antibiotic. The fat globules from both bovine and goat milk markedly reduced bacterial binding and invasion compared with controls, and the cells treated with goat milk-derived fat globules demonstrated greater protective properties than those derived from bovine milk. The effect of heat treatment on bovine fat globules was also investigated, and it was shown that the fat globules from heated milk had a higher degree of inhibition than those from unheated milk. 相似文献
366.
Baum?ngel sind unzureichende Zust?nde technischer Natur und nicht "bewilligungswidrige" Bauführungen. 相似文献
367.
Jinbin Lu Yunchao Mu Xiangwei Luo Jitai Niu 《Materials Science and Engineering: B》2012,177(20):1759-1763
Soldering of aluminum metal matrix composites (Al–SiC) to other structural materials, or even to themselves, has proved unsuccessful mainly due to the poor wetting of these composites by conventional soldering alloys. This paper reports a new approach, which improves the wetting properties of these composites by molting solder alloys to promote stronger bonds. The new approach relies on nickel-plating of the composite's faying surface prior to application of a solder alloy. Based on this approach, an aluminum metal matrix composite containing 55 vol.% SiC particles is successfully soldered to a Fe–Ni–Co alloy (commercially known as Kovar 4J29). The solder material is a zinc-based alloy (Zn–Cd–Ag–Cu) with a melting point of about 400 °C. Microscopic examinations of the aluminum metal matrix composites (Al-MMCs)–Kovar interfaces show that the nickel-plating, prior to soldering, could noticeably enhance the reaction between the molten solder and composites. The fractography of the shear-tested samples revealed that fracture occurs within the composite (i.e. cohesive failure), indicating a good adhesion between the solder alloy and the Al–SiC composite. 相似文献
368.
Paula Ketilly Nascimento Alves Andr Cruz William J. Silva Siegfried Labeit Anselmo Sigari Moriscot 《International journal of molecular sciences》2022,23(13)
microRNAs negatively regulate gene expression by blocking translation or increasing mRNA degradation. In skeletal muscle, these molecules play important roles in adaptive responses, and ongoing investigations are necessary to understand the fine-tune regulation of skeletal muscle mass. Herein we showed that skeletal muscle overexpression of miR-29c increased fiber size and force at 7 and 30 days after electrotransfer. At both time points, AKT/mTOR pathway components were downregulated, and, surprisingly, overall protein synthesis was strongly elevated at day 7, which normalized by day 30 after pCMVmiR-29c electrotransfer. These results indicate that miR-29c expression induces skeletal muscle hypertrophy and gain of function, which involves increased overall protein synthesis in spite of the deactivation of the AKT/mTOR pathway. 相似文献
369.
DXX68C29井是位于辛68块东三段构造高部位的一口关键井,2011年7月27日因出砂严重而停产,影响产能高达15.4m3。针对该井套窜井段长、封窜后套管内通径有所变化、井斜角变化大的矛盾,应用40臂井径仪测试结果对该井套管内通径的变化进行分析后选择合适的防砂工艺防砂后,较好地解决了该井因出砂不能正常生产的矛盾,并见到了明显效果,该井2011年8月4日开井,已连续生产170d,累计增油1 179.9m3。该技术在DXX68C29井的成功实践为解决同类井的防砂提供了一种新的思路。介绍了40臂井径仪结构、测试原理、技术指标,并通过现场实例应用,分析了该仪器现场应用效果,为解决油藏油井防砂提供了一种新的思路和技术支持。 相似文献
370.