全文获取类型
收费全文 | 420792篇 |
免费 | 6745篇 |
国内免费 | 1727篇 |
专业分类
电工技术 | 8259篇 |
综合类 | 846篇 |
化学工业 | 63441篇 |
金属工艺 | 14684篇 |
机械仪表 | 12327篇 |
建筑科学 | 12166篇 |
矿业工程 | 1055篇 |
能源动力 | 11447篇 |
轻工业 | 44566篇 |
水利工程 | 3451篇 |
石油天然气 | 2198篇 |
武器工业 | 77篇 |
无线电 | 56426篇 |
一般工业技术 | 77729篇 |
冶金工业 | 75257篇 |
原子能技术 | 5675篇 |
自动化技术 | 39660篇 |
出版年
2021年 | 2981篇 |
2020年 | 2050篇 |
2019年 | 2686篇 |
2018年 | 4077篇 |
2017年 | 4166篇 |
2016年 | 4440篇 |
2015年 | 3730篇 |
2014年 | 6202篇 |
2013年 | 19814篇 |
2012年 | 10756篇 |
2011年 | 15322篇 |
2010年 | 11864篇 |
2009年 | 13377篇 |
2008年 | 14398篇 |
2007年 | 14735篇 |
2006年 | 13159篇 |
2005年 | 12365篇 |
2004年 | 11830篇 |
2003年 | 11543篇 |
2002年 | 11189篇 |
2001年 | 11400篇 |
2000年 | 10454篇 |
1999年 | 10922篇 |
1998年 | 24128篇 |
1997年 | 17683篇 |
1996年 | 13968篇 |
1995年 | 11056篇 |
1994年 | 9827篇 |
1993年 | 9404篇 |
1992年 | 7162篇 |
1991年 | 6812篇 |
1990年 | 6419篇 |
1989年 | 6126篇 |
1988年 | 5872篇 |
1987年 | 4890篇 |
1986年 | 4837篇 |
1985年 | 5981篇 |
1984年 | 5608篇 |
1983年 | 4841篇 |
1982年 | 4503篇 |
1981年 | 4456篇 |
1980年 | 4213篇 |
1979年 | 4083篇 |
1978年 | 3774篇 |
1977年 | 4550篇 |
1976年 | 6099篇 |
1975年 | 3117篇 |
1974年 | 3011篇 |
1973年 | 2893篇 |
1972年 | 2320篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
11.
12.
13.
14.
15.
16.
Esteban Vera Pingitore María Silvina Juárez Tomás Birgitt Wiese 《Drug development and industrial pharmacy》2015,41(6):942-952
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities. 相似文献
17.
The Interplay of Modulus,Strength, and Ductility in Adhesive Design Using Biomimetic Polymer Chemistry 下载免费PDF全文
High‐performance adhesives require mechanical properties tuned to demands of the surroundings. A mismatch in stiffness between substrate and adhesive leads to stress concentrations and fracture when the bonding is subjected to mechanical load. Balancing material strength versus ductility, as well as considering the relationship between adhesive modulus and substrate modulus, creates stronger joints. However, a detailed understanding of how these properties interplay is lacking. Here, a biomimetic terpolymer is altered systematically to identify regions of optimal bonding. Mechanical properties of these terpolymers are tailored by controlling the amount of a methyl methacrylate stiff monomer versus a similar monomer containing flexible poly(ethylene glycol) chains. Dopamine methacrylamide, the cross‐linking monomer, is a catechol moiety analogous to 3,4‐dihydroxyphenylalanine, a key component in the adhesive proteins of marine mussels. Bulk adhesion of this family of terpolymers is tested on metal and plastic substrates. Incorporating higher amounts of poly(ethylene glycol) into the terpolymer introduces flexibility and ductility. By taking a systematic approach to polymer design, the region in which material strength and ductility are balanced in relation to the substrate modulus is found, thereby yielding the most robust joints. 相似文献
18.
19.
20.