全文获取类型
收费全文 | 40262篇 |
免费 | 3874篇 |
国内免费 | 733篇 |
专业分类
电工技术 | 631篇 |
综合类 | 1743篇 |
化学工业 | 15511篇 |
金属工艺 | 347篇 |
机械仪表 | 614篇 |
建筑科学 | 1420篇 |
矿业工程 | 145篇 |
能源动力 | 2680篇 |
轻工业 | 15837篇 |
水利工程 | 173篇 |
石油天然气 | 557篇 |
武器工业 | 19篇 |
无线电 | 517篇 |
一般工业技术 | 3377篇 |
冶金工业 | 372篇 |
原子能技术 | 169篇 |
自动化技术 | 757篇 |
出版年
2024年 | 253篇 |
2023年 | 775篇 |
2022年 | 2030篇 |
2021年 | 2315篇 |
2020年 | 1517篇 |
2019年 | 1543篇 |
2018年 | 1151篇 |
2017年 | 1348篇 |
2016年 | 1196篇 |
2015年 | 1368篇 |
2014年 | 1968篇 |
2013年 | 2131篇 |
2012年 | 2877篇 |
2011年 | 2879篇 |
2010年 | 2213篇 |
2009年 | 2016篇 |
2008年 | 1806篇 |
2007年 | 2400篇 |
2006年 | 2074篇 |
2005年 | 1811篇 |
2004年 | 1538篇 |
2003年 | 1285篇 |
2002年 | 1031篇 |
2001年 | 783篇 |
2000年 | 708篇 |
1999年 | 667篇 |
1998年 | 517篇 |
1997年 | 382篇 |
1996年 | 384篇 |
1995年 | 309篇 |
1994年 | 336篇 |
1993年 | 285篇 |
1992年 | 253篇 |
1991年 | 169篇 |
1990年 | 113篇 |
1989年 | 89篇 |
1988年 | 71篇 |
1987年 | 66篇 |
1986年 | 47篇 |
1985年 | 42篇 |
1984年 | 31篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 35篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1951年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Dr. Emrah Kara Dr. Nis Valentin Nielsen Bergrun Eggertsdottir Dr. Bernd Thiede Dr. Sandip M. Kanse Dr. Geir Åge Løset 《Chembiochem : a European journal of chemical biology》2020,21(13):1875-1884
We describe a novel, easy and efficient combinatorial phage display peptide substrate-mining method to map the substrate specificity of proteases. The peptide library is displayed on the pVII capsid of the M13 bacteriophage, which renders pIII necessary for infectivity and efficient retrieval, in an unmodified state. As capture module, the 3XFLAG was chosen due to its very high binding efficiency to anti-FLAG mAbs and its independency of any post-translational modification. This library was tested with Factor-VII activating protease (WT-FSAP) and its single-nucleotide polymorphism variant Marburg-I (MI)-FSAP. The WT-FSAP results confirmed the previously reported Arg/Lys centered FSAP cleavage site consensus as dominant, as well as reinforcing MI-FSAP as a loss-of-function mutant. Surprisingly, rare substrate clones devoid of basic amino acids were also identified. Indeed one of these peptides was cleaved as free peptide, thus suggesting a broader range of WT-FSAP substrates than previously anticipated. 相似文献
63.
《Food Control》2015
A diverse range of genetic elements has been used to develop genetically modified organisms (GMOs) over the last 18 years. Screening methods that target few elements, such as the Cauliflower Mosaic Virus 35S promoter (P-35S) and Agrobacterium tumefaciens nopaline terminator (T-nos), are not sufficient to screen GMOs. In the present study, a multiplex PCR system for all globally commercialized GM soybean events was developed to easily trace the events. For this purpose, screening elements of 24 GM soybean events were investigated and 9 screening targets were selected and divided into three individual triplex PCR systems: P-35S, ribulose-1,5-bisphosphate carboxylase small subunit promoter of Arabidopsis thaliana, T-nos, T-35S, pea E9 terminator, open reading frame 23 terminator of A. tumefaciens, proteinase inhibitor II terminator of potato, acetohydroxy acid synthase large subunit terminator of A. thaliana, and the revealed 3′ flanking sequences of DP-305423-1. The specificity of the assays was confirmed using thirteen GM soybean events as the respective positive/negative controls. The limit of detection of each multiplex set, as determined using certified reference materials of specific GM events, ranged from 0.03 to 0.5%, depending upon target. Furthermore, 26 food samples that contained soybean ingredients, which were purchased from the USA, China, Japan, and Korea, were analyzed, 17 of which contained one or more GM soybean events. These results suggest that the developed screening method can be used to efficiently track and identify 24 GM soybean events in food and feed. 相似文献
64.
Syafikah Huda Paiman Mukhlis A Rahman Khairul Hamimah Abas Azian Abd Aziz Ahmad Fauzi Ismail Mohd Hafiz Dzarfan Othman Juhana Jaafar Mohammad Noorul Anam Mohd Norddin 《化学工程与技术》2019,42(6):1321-1329
Removal by absorptive ceramic membranes can simultaneously absorb and separate metal ions from water. Alumina/yttria‐stabilized zirconia (Al2O3/YSZ) hollow‐fiber membranes, fabricated using phase inversion and sintering process, were deposited with iron oxide by an in‐situ hydrothermal process. The results showed that α‐Fe2O3 was produced and incorporated across the membranes. A reduction in flux was recorded with the deposition of α‐Fe2O3. However, it improved the adsorption capacity for heavy metal adsorption. The adsorption‐separation test demonstrated that the optimized membrane is able to completely remove Pb(II) ions after two hours. 相似文献
65.
66.
67.
Inhibition of Spore Germination of Phakopsora Pachyrhizi Using Crude Extracts of Amaranthus Spinosus
The effectiveness of methanolic and n-hexane crude extracts of Amaranthus spinosus to inhibit the spore germination of Phakopsora pachyrhizi, a causal agent of soybean rust disease was studied. Both methanolic and n-hexane crude extracts inhibited spore germination at concentrations of 0.1% to 5.0%. Methanolic extract of the roots at a concentration of 2.5% inhibited 55% of spore germination, and this result was similar when higher concentration at 5% of methanolic and n-hexane extracts of the flowers was used. The presence of alkaloids, flavonoids, tannins, saponins, and terpenoids in the extract may be responsible for the inhibition. The extract was potential to be utilized as a botanical fungicide. 相似文献
68.
Alice Maurer Prof. Dr. Florian P. Seebeck 《Chembiochem : a European journal of chemical biology》2020,21(20):2908-2911
Ergothioneine has emerged as a crucial cytoprotectant in the pathogenic lifestyle of Mycobacterium tuberculosis. Production of this antioxidant from primary metabolites may be regulated by phosphorylation of Thr213 in the active site of the methyltransferase EgtD. The structure of mycobacterial EgtD suggests that this post-translational modification would require a large-scale change in conformation to make the active-site residue accessible to a protein kinase. In this report, we show that, under in vitro conditions, EgtD is not a substrate of protein kinase PknD. 相似文献
69.
70.
Avtar Singh Soottawat Benjakul Nurul Huda 《International Journal of Food Science & Technology》2020,55(12):3553-3562
Effect of debittered salmon frame hydrolysate (DSFH) at various levels (0, 5, 10, 15, 20 and 25 g/100 g) on physicochemical, textural, sensory and nutritional properties of biscuits was investigated. The highest thickness was obtained for the sample with 25 g/100 g DSFH (P < 0.05). There was no difference in diameter among all the biscuit samples (P > 0.05). The samples added with DSFH had lower weight, water activity and moisture content than the control (CONT, without DSFH) (P < 0.05). DSFH at 15 g/100 g showed no detrimental effect on sensory properties of resulting biscuits (DSFH-15). The DSFH-15 biscuit showed reduction in cutting force and fracturability. Scanning electron microscopic and cross-sectional images showed that DSFH-15 biscuit had more porous structure, compared to the CONT. The biscuits fortified with 15 g/100 g DSFH had higher protein but had lower energy value, fat and carbohydrate content than the CONT. 相似文献