全文获取类型
收费全文 | 45906篇 |
免费 | 5357篇 |
国内免费 | 2360篇 |
专业分类
电工技术 | 12144篇 |
技术理论 | 2篇 |
综合类 | 3961篇 |
化学工业 | 3624篇 |
金属工艺 | 1750篇 |
机械仪表 | 1394篇 |
建筑科学 | 5797篇 |
矿业工程 | 1943篇 |
能源动力 | 942篇 |
轻工业 | 1839篇 |
水利工程 | 2045篇 |
石油天然气 | 3006篇 |
武器工业 | 249篇 |
无线电 | 4369篇 |
一般工业技术 | 2271篇 |
冶金工业 | 1918篇 |
原子能技术 | 468篇 |
自动化技术 | 5901篇 |
出版年
2024年 | 75篇 |
2023年 | 445篇 |
2022年 | 1006篇 |
2021年 | 1271篇 |
2020年 | 1222篇 |
2019年 | 1005篇 |
2018年 | 873篇 |
2017年 | 1151篇 |
2016年 | 1346篇 |
2015年 | 1622篇 |
2014年 | 3306篇 |
2013年 | 2322篇 |
2012年 | 3530篇 |
2011年 | 3970篇 |
2010年 | 3060篇 |
2009年 | 3169篇 |
2008年 | 2946篇 |
2007年 | 3479篇 |
2006年 | 3225篇 |
2005年 | 2684篇 |
2004年 | 2191篇 |
2003年 | 2031篇 |
2002年 | 1650篇 |
2001年 | 1410篇 |
2000年 | 1176篇 |
1999年 | 869篇 |
1998年 | 541篇 |
1997年 | 408篇 |
1996年 | 377篇 |
1995年 | 336篇 |
1994年 | 222篇 |
1993年 | 145篇 |
1992年 | 100篇 |
1991年 | 77篇 |
1990年 | 70篇 |
1989年 | 58篇 |
1988年 | 66篇 |
1987年 | 20篇 |
1986年 | 30篇 |
1985年 | 25篇 |
1984年 | 32篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 5篇 |
1977年 | 3篇 |
1965年 | 4篇 |
1961年 | 3篇 |
1959年 | 6篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
本文在环氧涂料中添加玄武岩鳞片,提高其防腐蚀性能。针对玄武岩鳞片的团聚问题,通过机械力化学改性工艺,采用正硅酸四乙酯、HY-311型钛酸酯偶联剂、E-44型环氧树脂对玄武岩鳞片进行杂化包覆,结果表明,杂化包覆后玄武岩鳞片的沉降时间从2h提高至96 h。杂化包覆玄武岩鳞片添加量为20%涂层的性能最优,附着力为13.40 MPa,耐盐雾时间为2000 h,在3.5%NaCl溶液中浸泡2000 h后,0.01 Hz的阻抗模值仍然有5.15×109 Ω·cm2。 相似文献
2.
Magalí Rey-Campos Beatriz Novoa Alberto Pallavicini Marco Gerdol Antonio Figueras 《International journal of molecular sciences》2021,22(6)
Mytimycins are cysteine-rich antimicrobial peptides that show antifungal properties. These peptides are part of the immune network that constitutes the defense system of the Mediterranean mussel (Mytilus galloprovincialis). The immune system of mussels has been increasingly studied in the last decade due to its great efficiency, since these molluscs, particularly resistant to adverse conditions and pathogens, are present all over the world, being considered as an invasive species. The recent sequencing of the mussel genome has greatly simplified the genetic study of some of its immune genes. In the present work, we describe a total of 106 different mytimycin variants in 16 individual mussel genomes. The 13 highly supported mytimycin clusters (A–M) identified with phylogenetic inference were found to be subject to the presence/absence variation, a widespread phenomenon in mussels. We also identified a block of conserved residues evolving under purifying selection, which may indicate the “functional core” of the mature peptide, and a conserved set of 10 invariable plus 6 accessory cysteines which constitute a plastic disulfide array. Finally, we extended the taxonomic range of distribution of mytimycins among Mytilida, identifying novel sequences in M. coruscus, M. californianus, P. viridis, L. fortunei, M. philippinarum, M. modiolus, and P. purpuratus. 相似文献
3.
4.
Targeted editing of intronic-splicing silencer enhancement of SMN2 Exon 7 inclusion by CRISPR/Case 9
LIUCHENG WU YI WANG LILI DU GUIQING JI RUI ZHOU ZEYI ZHAO JUN CHEN SHUNXING ZHU 《Biocell》2021,45(6):1501-1507
Spinal muscular atrophy (SMA) is an autosomal recessive hereditary neuromuscular disease. Exon 7 and 8 of survival of motor neuron 1 (SMN1) gene or only exon 7 homology deletion leads to the failure to produce a full-length SMN gene. The copy number of SMN2 gene with high homology of SMN1 affects the degree of disease and was the target gene for targeting therapy, in which splicing silencer in intron 7 was the key to suppress the inclusion of exon 7. In this study, we projected to use CRISPR/Case 9 for the targeted editing of intronic-splicing silencer (ISS) sequence to promote the inclusion of SMN2 exon 7 and increase the production of SMN2 full-length (FL) gene expression. It happens that there was a protospacer adjacent motif (PAM) at one end of the ISS sequence according to the design of sgRNA. The recombinant vector of sgRNA HSMN2 CRISPR/Case 9 was constructed and transfected into HEK293 cells. Sequencing results showed that the ISS sequence could be edited accurately and targeting in the predicted direction, in which deleting small fragments, inserting small amounts and mutation. Quantitative analysis of RT-PCR products by restriction enzyme of DdeI digestion showed that the FL of SMN2 increased by 8% (P < 0.05). In the primary cultured chondrocytes of SMA mice, in which sgRNA HSMN2 CRISPR/Case9 recombinant vector transfection could increase the SMN2 FL gene by 23% (P < 0.05) and significantly improve SMN protein levels (P < 0.05). CRISPR/Case 9 is an effective tool for gene editing and therapy of hereditary diseases, but it is rarely reported in the treatment of SMA diseases. This study shows that CRISPR/Case 9 was first used for the precision target of ISS sequence editing, which can effectively promote the production of SMN2 FL gene expressions, in which there was an important clinical reference value. 相似文献
5.
Marc De Doncker Chloé De Graeve Dr. Jorick Franceus Dr. Koen Beerens Prof. Vladimír Křen Dr. Helena Pelantová Dr. Ronny Vercauteren Prof. Dr. Tom Desmet 《Chembiochem : a European journal of chemical biology》2021,22(23):3319-3325
The substantial increase in DNA sequencing efforts has led to a rapid expansion of available sequences in glycoside hydrolase families. The ever-increasing sequence space presents considerable opportunities for the search for enzymes with novel functionalities. In this work, the sequence-function space of glycoside hydrolase family 94 (GH94) was explored in detail, using a combined approach of phylogenetic analysis and sequence similarity networks. The identification and experimental screening of unknown clusters led to the discovery of an enzyme from the soil bacterium Paenibacillus polymyxa that acts as a 4-O-β-d -glucosyl-d -galactose phosphorylase (GGalP), a specificity that has not been reported to date. Detailed characterization of GGalP revealed that its kinetic parameters were consistent with those of other known phosphorylases. Furthermore, the enzyme could be used for production of the rare disaccharides 4-O-β-d -glucosyl-d -galactose and 4-O-β-d -glucosyl-l -arabinose. Our current work highlights the power of rational sequence space exploration in the search for novel enzyme specificities, as well as the potential of phosphorylases for rare disaccharide synthesis. 相似文献
6.
7.
《全球能源互联网(英文)》2022,5(6):618-626
A novel image sequence-based risk behavior detection method to achieve high-precision risk behavior detection for power maintenance personnel is proposed in this paper. In this method, the original image sequence data is first separated from the foreground and background. Then, the free anchor frame detection method is used in the foreground image to detect the personnel and correct their direction. Finally, human posture nodes are extracted from each frame of the image sequence, which are then used to identify the abnormal behavior of the human. Simulation experiment results demonstrate that the proposed algorithm has significant advantages in terms of the accuracy of human posture node detection and risk behavior identification. 相似文献
8.
9.
Sofia Melchior Sonia Calligaris Marilena Marino Francesca D’Este Giorgio Honsell Maria Cristina Nicoli Nadia Innocente 《International Journal of Food Science & Technology》2022,57(5):3106-3115
This research aimed at studying the potential use of monoglyceride (MG) structured emulsions (MSEs) as delivery and protective systems for probiotic bacteria in Ricotta cheese. To this purpose, a low-fat commercial Ricotta cheese was added with MSEs formulated with milk, as water phase, and sunflower oil (MSE-SO) or anhydrous milk fat (MSE-AMF), as lipid phase. A commercial whole milk Ricotta cheese (W-RC) was considered as reference. A probiotic Lacticaseibacillus rhamnosus strain was inoculated as free cells in W-RC or embedded into the MSEs and added to the low-fat Ricotta at the same reference fat content. After physico-chemical characterisation, L. rhamnosus viability and sample destructuring behaviour upon in vitro digestion were evaluated. At the end of in vitro digestion, both W-RC and sample containing MSE-SO were unable to protect cells. By contrast, sample with AMF ensured a sufficient probiotic viability, even after 14 days of storage at 4 °C. This result was attributed to system composition and structure. During the gastric phase, the presence of caseins and MG-AMF mixed structures induced the formation of clots, entrapping and protecting cells against the acidic pH of the stomach, as confirmed by confocal micrographs and particle size. During the intestinal phase, cell viability was guaranteed by the formation of mixed micelles promoted by MG. It was demonstrated that microbial cells located near MG structures where they found protection. 相似文献
10.
《Ceramics International》2022,48(4):5091-5099
The impact of the addition of TiO2 nanoparticles and nanowires on the morphology, phase characteristics, contact angle, and electrochemical performance of chemically bonded phosphate ceramic coatings (CBPCs) was investigated. The chemical composition and surface morphology of the TiO2 nanoparticle and nanowire modified with and without (heptadecafluoro-1,1,2,2-tetradecyl) trimethoxysilane were characterized. Results indicated that the hydrophobic –CF2– and –CF3 groups were successfully introduced into the TiO2 nanoparticles and nanowires after modification. Corrosion resistance of CBPCs with TiO2 was evidently improved compared with that without TiO2. Such improvement was mainly due to the combined effects of low surface energy materials and micro/nano structures. In addition, CBPCs with TiO2 nanowires exhibited higher hydrophobicity and corrosion resistance than those with TiO2 nanoparticles because of the special columnar structure of the nanowires. 相似文献