首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   434286篇
  免费   8266篇
  国内免费   1396篇
电工技术   7868篇
综合类   361篇
化学工业   66502篇
金属工艺   14622篇
机械仪表   12352篇
建筑科学   12294篇
矿业工程   925篇
能源动力   11492篇
轻工业   47918篇
水利工程   3517篇
石油天然气   1914篇
武器工业   18篇
无线电   56247篇
一般工业技术   80251篇
冶金工业   79858篇
原子能技术   5643篇
自动化技术   42166篇
  2021年   3239篇
  2020年   2364篇
  2019年   3042篇
  2018年   4914篇
  2017年   4899篇
  2016年   5235篇
  2015年   4275篇
  2014年   6639篇
  2013年   21167篇
  2012年   11628篇
  2011年   15914篇
  2010年   12321篇
  2009年   13780篇
  2008年   14791篇
  2007年   15111篇
  2006年   13317篇
  2005年   12424篇
  2004年   11995篇
  2003年   11663篇
  2002年   11286篇
  2001年   11365篇
  2000年   10508篇
  1999年   11018篇
  1998年   25410篇
  1997年   18523篇
  1996年   14501篇
  1995年   11353篇
  1994年   10040篇
  1993年   9691篇
  1992年   7240篇
  1991年   6919篇
  1990年   6491篇
  1989年   6215篇
  1988年   5963篇
  1987年   4978篇
  1986年   4915篇
  1985年   6074篇
  1984年   5678篇
  1983年   4892篇
  1982年   4573篇
  1981年   4534篇
  1980年   4292篇
  1979年   4124篇
  1978年   3813篇
  1977年   4710篇
  1976年   6459篇
  1975年   3147篇
  1974年   3047篇
  1973年   2932篇
  1972年   2335篇
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
81.
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   
82.
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   
83.
JOM - Alpha-radiation damage in metals is a concern for long-term radioactive storage and systems that produce nuclear energy. Accurate prediction of irradiated material properties and failure...  相似文献   
84.
85.
86.
87.
88.
89.
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号