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   20167篇
  免费   2353篇
  国内免费   168篇
电工技术   23篇
综合类   600篇
化学工业   5818篇
金属工艺   109篇
机械仪表   288篇
建筑科学   95篇
矿业工程   8篇
能源动力   36篇
轻工业   13926篇
水利工程   51篇
石油天然气   37篇
无线电   274篇
一般工业技术   842篇
冶金工业   69篇
原子能技术   50篇
自动化技术   462篇
  2025年   87篇
  2024年   670篇
  2023年   571篇
  2022年   1403篇
  2021年   1498篇
  2020年   970篇
  2019年   958篇
  2018年   778篇
  2017年   875篇
  2016年   779篇
  2015年   861篇
  2014年   972篇
  2013年   1132篇
  2012年   1216篇
  2011年   1215篇
  2010年   906篇
  2009年   798篇
  2008年   735篇
  2007年   957篇
  2006年   841篇
  2005年   706篇
  2004年   590篇
  2003年   436篇
  2002年   397篇
  2001年   268篇
  2000年   223篇
  1999年   257篇
  1998年   164篇
  1997年   127篇
  1996年   181篇
  1995年   169篇
  1994年   180篇
  1993年   146篇
  1992年   136篇
  1991年   92篇
  1990年   66篇
  1989年   71篇
  1988年   49篇
  1987年   56篇
  1986年   36篇
  1985年   35篇
  1984年   28篇
  1983年   6篇
  1982年   4篇
  1981年   3篇
  1980年   28篇
  1979年   4篇
  1978年   2篇
  1976年   3篇
  1973年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
《Drying Technology》2007,25(7):1193-1201
This work describes how probiotic bacteria can be dried at low temperature in two steps, combining spray drying and vacuum drying, in order to enhance their survival during storage. A sufficient number of dried probiotics survived storage for more than 3 months at 30°C, if an appropriate combination of protein and carbohydrate was selected as carrier and storage conditions were maintained optimal. The use of soy protein and maltodextrin or skim milk and arabic gum resulted in the best survival rates of probiotics during storage. No evident difference was found between different spray dryer configurations, although a cocurrent flow was preferred.  相似文献   
2.
A Saccharomyces cerevisiae sequence cloned by serendipity was found to encode a protein that is a new member of the Ypt/Rab monomeric G-protein family. This sequence shows high homology to the yeast genes SEC4 and YPT1 and, like SEC4 and YPT1, is essential for viability. The sequence was localized to chromosome V based upon hybridization to pulse-field gel-separated yeast chromosomes. The sequence has been deposited in the GenBank data library under Accession Number L17070.  相似文献   
3.
4.
We have identified three yeast genes, KES1, HES1 and OSH1, whose products show homology to the human oxysterol binding protein (OSBP). Mutations in these genes resulted in pleiotropic sterol-related phenotypes. These include tryptophan-transport defects and nystatin resistance, shown by double and triple mutants. In addition, mutant combinations showed small but apparently cumulative reductions in membrane ergosterol levels. The three yeast genes are also functionally related as overexpression of HES1 or KES1 alleviated the tryptophan-transport defect in kes1Δ or osh1Δ mutants, respectively. Our study implicates this new yeast gene family in ergosterol synthesis and provides comparative evidence of a role for human OSBP in cholesterol synthesis.  相似文献   
5.
We have isolated a mutant which exhibits partial constitutivity for a -specific gene expression in α cells. The wild-type gene was cloned and demonstrated to be allelic to the STE13 gene, which encodes the dipeptidyl aminopeptidase involved in processing of the α-factor prepropheromone. Thus, the mating defect of the ste13 mutations in α cells may result both from the production of incompletely processed α-factor and from the increased expression of a -specific genes. The STE13 open reading frame of 931 amino acids contains a putative membrane-spanning segment near its amino terminus and is 31% identical to a second yeast dipeptidyl aminopeptidase (DAP2). A null mutant of STE13 has been constructed: it is viable and sporulation-proficient. The sequence has been deposited in the GenBank data library under Accession Number L21944.  相似文献   
6.
Whey is an undurable product. treated very often as a waste which pollutes the natural environment. Whey which is a valuable source of protein, lactose, vitamins and mineral salts should be utilized completely. The present paper is a proposal of whey drying on porous carriers. It is proved experimentally that the proposed drying method guarantees good product quality.  相似文献   
7.
Robert Rodošek 《Constraints》2001,6(2-3):257-269
This paper presents an hybrid algorithm for deriving 3-D structures of cyclic polypeptides. The algorithm combines constraint-based techniques with the most widely used methods for non-cyclic polypeptides. The empirical results demonstrate that the proposed hybrid algorithm outperforms traditional methods especially with respect to running times.  相似文献   
8.
八钢型材厂运用的电气隔离保护技术,在不同工况下的实际应用。  相似文献   
9.
Combining scanning force and fluorescent microscopy allows simultaneous identification of labeled biomolecules and analysis of their nanometer level architectural arrangement. Fluorescent polystyrene nano-spheres were used as reliable objects for alignment of optical and topographic images. This allowed the precise localization of different fluorescence particles within complex molecular assemblies whose structure was mapped in nanometer detail topography. Our experiments reveal the versatility of this method for analysis of proteins and protein–DNA complexes.  相似文献   
10.
An in-vitro method using commercially available enzymes for the prediction of the in-vivo digestible crude protein content was developed and tested on seven feedstuffs and 16 diets for pigs. Fat-extracted feed samples were consecutively incubated with pepsin at pH 1 and pancreatin at pH 6.8. From the nitrogen content of the feed sample and of the residue after incubation the in-vitro digestibility of the crude protein was calculated. Using the linear regression of in-vitro on in-vivo digestible crude protein of samples obtained in feeding trials, the in-vivo digestible crude protein content (DXPp) in g kg?1 dry matter could be predicted. For feedstuffs and diets the correlation was 0.99 and 0.95 and the residual standard deviation 17 and 6 g kg?1 dry matter, respectively. In a similar procedure the nitrogen solubilised during incubation with enzymes was analysed. The regression value was similar to that of the original procedure. However, this procedure was abandoned because it was more laborious.  相似文献   
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