全文获取类型
收费全文 | 498篇 |
免费 | 37篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 341篇 |
金属工艺 | 7篇 |
机械仪表 | 5篇 |
建筑科学 | 14篇 |
矿业工程 | 1篇 |
能源动力 | 13篇 |
轻工业 | 66篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 11篇 |
一般工业技术 | 48篇 |
冶金工业 | 7篇 |
自动化技术 | 16篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 101篇 |
2021年 | 116篇 |
2020年 | 28篇 |
2019年 | 20篇 |
2018年 | 18篇 |
2017年 | 12篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 27篇 |
2013年 | 22篇 |
2012年 | 31篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 8篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1986年 | 3篇 |
1984年 | 5篇 |
1982年 | 2篇 |
排序方式: 共有535条查询结果,搜索用时 15 毫秒
431.
432.
Elzbieta Lewandowska 《Journal of Sulfur Chemistry》2016,37(2):123-133
The addition of alkyl or aryl thiols to α-nitro or β-nitrocinnamate in the presence of base provided Michael addition products. In the case of β-nitro compounds reaction occurred via the formation of anti-Michael adducts. Selective nitro reduction of α-nitroadducts gives access to β-thio-α-amino acid derivatives. 相似文献
433.
Karolina Oszust Magdalena Fr?c Agata Gryta Nina Bilińska 《International journal of molecular sciences》2014,15(6):9907-9923
The knowledge about microorganisms—activity and diversity under hop production is still limited. We assumed that, different systems of hop production (within the same soil and climatic conditions) significantly influence on the composition of soil microbial populations and its functional activity (metabolic potential). Therefore, we compared a set of soil microbial properties in the field experiment of two hop production systems (a) ecological based on the use of probiotic preparations and organic fertilization (b) conventional—with the use of chemical pesticides and mineral fertilizers. Soil analyses included following microbial properties: The total number microorganisms, a bunch of soil enzyme activities, the catabolic potential was also assessed following Biolog EcoPlates®. Moreover, the abundance of ammonia-oxidizing archaea (AOA) was characterized by terminal restriction fragment length polymorphism analysis (T-RFLP) of PCR ammonia monooxygenase α-subunit (amoA) gene products. Conventional and ecological systems of hop production were able to affect soil microbial state in different seasonal manner. Favorable effect on soil microbial activity met under ecological, was more probably due to livestock-based manure and fermented plant extracts application. No negative influence on conventional hopyard soil was revealed. Both type of production fulfilled fertilizing demands. Under ecological production it was due to livestock-based manure fertilizers and fermented plant extracts application. 相似文献
434.
Krzysztof ukowicz Barbara Zagrajczuk Karolina Truchan ukasz Niedzwiedzki Katarzyna Cholewa-Kowalska Anna M. Osyczka 《International journal of molecular sciences》2022,23(5)
In this work, a poly(L-lactide-co-glycolide) (PLGA)-based composite was enriched with one of the following sol-gel bioactive glasses (SBG) at 50 wt.%: A1—40 mol% SiO2, 60 mol% CaO, CaO/SiO2 ratio of 1.50; S1—80 mol% SiO2, 20 mol% CaO, CaO/SiO2 ratio of 0.25; A2—40 mol% SiO2, 54 mol% CaO, 6 mol% P2O5, CaO/SiO2 ratio of 1.35; S2—80 mol% SiO2,16 mol% CaO, 4 mol% P2O5, CaO/SiO2 ratio of 0.20. The composites and PLGA control sheets were then soaked for 24 h in culture media, and the obtained condition media (CM) were used to treat human bone marrow stromal cells (hBMSCs) for 72 h. All CMs from the composites increased ERK 1/2 activity vs. the control PLGA CM. However, expressions of cell migration-related c-Fos, osteopontin, matrix metalloproteinase-2, C-X-C chemokine receptor type 4, vascular endothelial growth factor, and bone morphogenetic protein 2 were significantly increased only in cells treated with the CM from the A1/PLGA composite. This CM also significantly increased the rate of human BMSC migration but did not affect cell metabolic activity. These results indicate important biological markers that are upregulated by products released from the bioactive composites of a specific chemical composition, which may eventually prompt osteoprogenitor cells to colonize the bioactive material and accelerate the process of tissue regeneration. 相似文献
435.
Barbara Szutkowska Klaudia Wieczorek Ryszard Kierzek Pawel Zmora Jake M. Peterson Walter N. Moss David H. Mathews Elzbieta Kierzek 《International journal of molecular sciences》2022,23(5)
Influenza A virus (IAV) is a member of the single-stranded RNA (ssRNA) family of viruses. The most recent global pandemic caused by the SARS-CoV-2 virus has shown the major threat that RNA viruses can pose to humanity. In comparison, influenza has an even higher pandemic potential as a result of its high rate of mutations within its relatively short (<13 kbp) genome, as well as its capability to undergo genetic reassortment. In light of this threat, and the fact that RNA structure is connected to a broad range of known biological functions, deeper investigation of viral RNA (vRNA) structures is of high interest. Here, for the first time, we propose a secondary structure for segment 8 vRNA (vRNA8) of A/California/04/2009 (H1N1) formed in the presence of cellular and viral components. This structure shows similarities with prior in vitro experiments. Additionally, we determined the location of several well-defined, conserved structural motifs of vRNA8 within IAV strains with possible functionality. These RNA motifs appear to fold independently of regional nucleoprotein (NP)-binding affinity, but a low or uneven distribution of NP in each motif region is noted. This research also highlights several accessible sites for oligonucleotide tools and small molecules in vRNA8 in a cellular environment that might be a target for influenza A virus inhibition on the RNA level. 相似文献
436.
Agnieszka Wnuk Joanna Rzemieniec Karolina Przepirska Bernadeta Angelika Pietrzak Marzena Makowiak Magorzata Kajta 《International journal of molecular sciences》2021,22(23)
Triclocarban is a highly effective and broadly used antimicrobial agent. Humans are continually exposed to triclocarban, but the safety of prenatal exposure to triclocarban in the context of neurodevelopment remains unknown. In this study, we demonstrated for the first time that mice that had been prenatally exposed to environmentally relevant doses of triclocarban had impaired estrogen receptor 1 (ESR1) signaling in the brain. These mice displayed decreased mRNA and protein expression levels of ESR1 as well as hypermethylation of the Esr1 gene in the cerebral cortex. Prenatal exposure to triclocarban also diminished the mRNA expression of Esr2, Gper1, Ahr, Arnt, Cyp19a1, Cyp1a1, and Atg7, and the protein levels of CAR, ARNT, and MAP1LC3AB in female brains and decreased the protein levels of BCL2, ARNT, and MAP1LC3AB in male brains. In addition, exposure to triclocarban caused sex-specific alterations in the methylation levels of global DNA and estrogen receptor genes. Microarray and enrichment analyses showed that, in males, triclocarban dysregulated mainly neurogenesis-related genes, whereas, in females, the compound dysregulated mainly neurotransmitter-related genes. In conclusion, our data identified triclocarban as a neurodevelopmental risk factor that particularly targets ESR1, affects apoptosis and autophagy, and in sex-specific ways disrupts the epigenetic status of brain tissue and dysregulates the postnatal expression of neurogenesis- and neurotransmitter-related genes. 相似文献
437.
The selection of the appropriate extraction method is crucial, especially for the receiving of active substances from plant material. The extraction using supercritical liquids and micellar-mediated extraction (MME) is the most advantageous among the alternative methods to classical solid–liquid extraction. However, the latter seems to be the best solution when the desired actives are polar. The following article presents a comprehensive review of the micellar-mediated extraction method in the last decade. The theoretical principle of the process was also refreshed and the current state of knowledge on the applications for analytical and manufacturing purposes was summarized. 相似文献
438.
Paula Ossowicz-Rupniewska Joanna Klebeko Ewelina
witek Karolina Bilska Anna Nowak Wiktoria Duchnik ukasz Kucharski ukasz Struk Karolina Wenelska Adam Klimowicz Ewa Janus 《International journal of molecular sciences》2022,23(8)
Modifications of (RS)-2-[4-(2-methylpropyl)phenyl] propanoic acid with amino acid isopropyl esters were synthesised using different methods via a common intermediate. The main reaction was the esterification of the carboxyl group of amino acids with isopropanol and chlorination of the amino group of the amino acid, followed by an exchange or neutralisation reaction and protonation. All of the proposed methods were very efficient, and the compounds obtained have great potential to be more effective drugs with increased skin permeability compared with ibuprofen. In addition, it was shown how the introduction of a modification in the form of an ion pair affects the properties of the obtained compound. 相似文献
439.
Teresa Janas Pawel Janas Karolina Sapo Tadeusz Janas 《International journal of molecular sciences》2020,21(22)
Intraluminal vesicles (ILVs) are released into the extracellular space as exosomes after the fusion of multivesicular bodies (MVBs) with the plasma membrane. miRNAs are delivered to the raft-like region of MVB by RNA-binding proteins (RBPs). RNA loading into exosomes can be either through direct interaction between RNA and the raft-like region of the MVB membrane, or through interaction between an RBP–RNA complex with this raft-like region. Selection of RNA aptamers that bind to lipid raft region of liposomal membranes was performed using the selection-amplification (SELEX) method. The pool of RNA aptamers was isolated, and the binding of this pool to lipid-raft regions was demonstrated. Sequencing of clones from rafted liposome-eluted RNAs showed sequences apparently of independent origin. Bioinformatics analysis revealed the most frequent raft-motifs present within these sequences. Four raft RNA motifs, one of them an EXO motif, have been identified. These motifs appear to be most frequent both in the case of raft RNA aptamers and in the case of exosomal pro-tumoral miRNAs transferred from cancer cells to macrophages, natural killer cells and dendritic cells, thus suggesting that the selection for incorporation of these miRNAs into ILVs is based on their affinity to the raft-like region of the MVB membrane. 相似文献
440.
Natalia Wojciechowska Shirin Alipour Ewelina Stolarska Karolina Bilska Pascal Rey Ewa M. Kalemba 《International journal of molecular sciences》2020,21(23)
The levels of methionine sulfoxide (MetO) and the abundances of methionine sulfoxide reductases (Msrs) were reported as important for the desiccation tolerance of Acer seeds. To determine whether the MetO/Msrs system is related to reactive oxygen species (ROS) and involved in the regulation of germination in orthodox and recalcitrant seeds, Norway maple and sycamore were investigated. Changes in water content, MetO content, the abundance of MsrB1 and MsrB2 in relation to ROS content and the activity of reductases depending on nicotinamide adenine dinucleotides were monitored. Acer seeds differed in germination speed—substantially higher in sycamore—hydration dynamics, levels of hydrogen peroxide, superoxide anion radicals (O2•−) and hydroxyl radicals (•OH), which exhibited peaks at different stages of germination. The MetO level dynamically changed, particularly in sycamore embryonic axes, where it was positively correlated with the levels of O2•− and the abundance of MsrB1 and negatively with the levels of •OH and the abundance of MsrB2. The MsrB2 abundance increased upon sycamore germination; in contrast, it markedly decreased in Norway maple. We propose that the ROS–MetO–Msr redox system, allowing balanced Met redox homeostasis, participates in the germination process in sycamore, which is characterized by a much higher speed compared to Norway maple. 相似文献