全文获取类型
收费全文 | 6613篇 |
免费 | 429篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 65篇 |
综合类 | 10篇 |
化学工业 | 2853篇 |
金属工艺 | 83篇 |
机械仪表 | 87篇 |
建筑科学 | 269篇 |
矿业工程 | 35篇 |
能源动力 | 167篇 |
轻工业 | 1153篇 |
水利工程 | 46篇 |
石油天然气 | 36篇 |
无线电 | 273篇 |
一般工业技术 | 988篇 |
冶金工业 | 328篇 |
原子能技术 | 18篇 |
自动化技术 | 642篇 |
出版年
2024年 | 54篇 |
2023年 | 129篇 |
2022年 | 678篇 |
2021年 | 793篇 |
2020年 | 266篇 |
2019年 | 215篇 |
2018年 | 254篇 |
2017年 | 209篇 |
2016年 | 265篇 |
2015年 | 225篇 |
2014年 | 275篇 |
2013年 | 451篇 |
2012年 | 377篇 |
2011年 | 423篇 |
2010年 | 281篇 |
2009年 | 276篇 |
2008年 | 279篇 |
2007年 | 246篇 |
2006年 | 214篇 |
2005年 | 153篇 |
2004年 | 139篇 |
2003年 | 113篇 |
2002年 | 99篇 |
2001年 | 55篇 |
2000年 | 47篇 |
1999年 | 55篇 |
1998年 | 35篇 |
1997年 | 42篇 |
1996年 | 44篇 |
1995年 | 36篇 |
1994年 | 36篇 |
1993年 | 31篇 |
1992年 | 27篇 |
1991年 | 16篇 |
1990年 | 23篇 |
1989年 | 11篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 17篇 |
1982年 | 6篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1974年 | 4篇 |
1966年 | 5篇 |
排序方式: 共有7053条查询结果,搜索用时 15 毫秒
1.
2.
Levén L Nyberg K Korkea-Aho L Schnürer A 《The Science of the total environment》2006,364(1-3):229-238
This study focuses on the presence of phenols in digestate from seven Swedish large-scale anaerobic digestion processes and their impact on the activity of ammonia oxidising bacteria (AOB) in soil. In addition, the importance of feedstock composition and phenol degradation capacity for the occurrence of phenols in the digestate was investigated in the same processes. The results revealed that the content of phenols in the digestate was related to the inhibition of the activity of AOB in soil (EC(50)=26 microg phenols g(-1) d.w. soil). In addition, five pure phenols (phenol, o-, p-, m-cresol and 4-ethylphenol) inhibited the AOB to a similar extent (EC(50)=43-110 microg g(-1) d.w. soil). The phenol content in the digestate was mainly dependent on the composition of the feedstock, but also to some extent by the degradation capacity in the anaerobic digestion process. Swine manure in the feedstock resulted in digestate containing higher amounts of phenols than digestate from reactors with less or no swine manure in the feedstock. The degradation capacity of phenol and p-cresol was studied in diluted small-scale batch cultures and revealed that anaerobic digestion at mesophilic temperatures generally exhibited a higher degradation capacity compared to digestion at thermophilic temperature. Although phenol, p-cresol and 4-ethylphenol were quickly degraded in soil, the phenols added with the digestate constitute an environmental risk according to the guideline values for contaminated soils set by the Swedish Environmental Protection Agency. In conclusion, the management of anaerobic digestion processes is of decisive importance for the production of digestate with low amounts of phenols, and thereby little risks for negative effects of the phenols on the soil ecosystem. 相似文献
3.
Anna Klingman 《Architectural Theory Review》2013,18(1):19-35
This article situates the contemporary position of architecture within a more general analysis of the transformation of commodities from tradabie objects to the commodified experiences of subjects. To understand this paradigmatic shift from the material properties of the object to the effects it generates for the subject, a conceptual analogy to Le Corbusier's book Towards a New Architecture is proposed. In the chapter “Liners, Airplanes, Automobiles,” Le Corbusier explores the programmatic and aesthetic attributes of contemporary commodities and their conditional relationship to the economic, social, and technological forces that formed the zeitgeist of the modern era. The article investigates how the very same products discussed in Le Corbusier's manifesto still apply to architectural discourse today, yet with other prefixes and other possible conclusions that pertain to the information age. Departing from the premise that architecture is a cultural commodity that supports and substantiates aspects of late capitalist commodity production, current consumer trends are examined in order to speculate on the potential of architecture to act as a catalyst for new experiences and perceptions. 相似文献
4.
Anna Skrzyska Anna Albrecht ukasz Albrecht 《Advanced Synthesis \u0026amp; Catalysis》2016,358(17):2838-2844
A novel approach for the stereoselective synthesis of benzothiophene derivatives with a fused dihydropyran moiety is demonstrated. The reaction of 2‐alkylidenebenzothiophene‐3(2H)‐ones with dienamines derived from α,β‐unsaturated aldehydes and chiral secondary amines proceeds according to the inverse‐electron‐demand hetero‐Diels–Alder pathway. The formation of the aromatic benzothiophene moiety is a driving force for the developed reaction cascade. Target products bearing three adjacent stereogenic centers are obtained in excellent yields and in a highly stereoselective manner.
5.
Anna Torres Monika Zaborek-yczba Jakub yczba Paulina Mertowska Sebastian Mertowski Ewelina Grywalska 《International journal of molecular sciences》2022,23(22)
Lichen sclerosus (LS) is defined as a chronic mucocutaneous inflammatory disease with a localization predominantly to the anus and genitals (vulvar sclerosus (VLS)). Pediatric lichen sclerosus (LS) is a chronic inflammatory skin condition with predilection for the anogenital area that if untreated can lead to scarring. Vulvar LS is characterized by two peaks in incidence: it occurs in prepubertal girls and in postmenopausal women. To date, several mechanisms and risk factors have been proposed in the pathogenesis of pediatric vulvar LS; however, the etiology of this condition is still not fully understood and constitutes a challenge for scientists and clinicians. The presented research aimed to systematically review the existing literature on the pathogenesis of pediatric LS and to identify possible underlying autoimmune mechanisms and molecular networks. The clinical presentation of pediatric lichen sclerosus and available treatment modalities are also presented to acquaint a broader audience with this underdiagnosed and undertreated condition. As a result of our review, we discuss several potential mechanisms, molecules, and pathways that have been recognized in this disease. The purpose of our review was also to summarize what we can induce in further studies, which will ultimately help to identify the mechanism responsible for the disease and aid in the development of new, more effective treatment strategies for diagnosis and treatment by clinicians and researchers. 相似文献
6.
Anna Pawlik Sylwia Stefanek Grzegorz Janusz 《International journal of molecular sciences》2022,23(22)
Extensive research efforts have been devoted to describing yeast alcohol oxidase (AO) and its promoter region, which is vastly applied in studies of heterologous gene expression. However, little is known about basidiomycetous AO and its physiological role in wood degradation. This review describes several alcohol oxidases from both white and brown rot fungi, highlighting their physicochemical and kinetic properties. Moreover, the review presents a detailed analysis of available AO-encoding gene promoter regions in basidiomycetous fungi with a discussion of the manipulations of culture conditions in relation to the modification of alcohol oxidase gene expression and changes in enzyme production. The analysis of reactions catalyzed by lignin-modifying enzymes (LME) and certain lignin auxiliary enzymes (LDA) elucidated the possible involvement of alcohol oxidase in the degradation of derivatives of this polymer. Combined data on lignin degradation pathways suggest that basidiomycetous AO is important in secondary reactions during lignin decomposition by wood degrading fungi. With numerous alcoholic substrates, the enzyme is probably engaged in a variety of catalytic reactions leading to the detoxification of compounds produced in lignin degradation processes and their utilization as a carbon source by fungal mycelium. 相似文献
7.
Ruiling Li Alex Maioli Zhe Yan Yuling Bai Danila Valentino Anna Maria Milani Valerio Pompili Cinzia Comino Sergio Lanteri Andrea Moglia Alberto Acquadro 《International journal of molecular sciences》2022,23(23)
Phytophthora infestans, the causal agent of late blight (LB) in tomato (Solanum lycopersicum L.), is a devastating disease and a serious concern for plant productivity. The presence of susceptibility (S) genes in plants facilitates pathogen proliferation; thus, disabling these genes may help provide a broad-spectrum and durable type of tolerance/resistance. Previous studies on Arabidopsis and tomato have highlighted that knock-out mutants of the PMR4 susceptibility gene are tolerant to powdery mildew. Moreover, PMR4 knock-down in potato has been shown to confer tolerance to LB. To verify the same effect in tomato in the present study, a CRISPR–Cas9 vector containing four single guide RNAs (sgRNAs: sgRNA1, sgRNA6, sgRNA7, and sgRNA8), targeting as many SlPMR4 regions, was introduced via Agrobacterium-tumefaciens-mediated transformation into two widely grown Italian tomato cultivars: ‘San Marzano’ (SM) and ‘Oxheart’ (OX). Thirty-five plants (twenty-six SM and nine OX) were selected and screened to identify the CRISPR/Cas9-induced mutations. The different sgRNAs caused mutation frequencies ranging from 22.1 to 100% and alternatively precise insertions (sgRNA6) or deletions (sgRNA7, sgRNA1, and sgRNA8). Notably, sgRNA7 induced in seven SM genotypes a −7 bp deletion in the homozygous status, whereas sgRNA8 led to the production of fifteen SM genotypes with a biallelic mutation (−7 bp and −2 bp). Selected edited lines were inoculated with P. infestans, and four of them, fully knocked out at the PMR4 locus, showed reduced disease symptoms (reduction in susceptibility from 55 to 80%) compared to control plants. The four SM lines were sequenced using Illumina whole-genome sequencing for deeper characterization without exhibiting any evidence of mutations in the candidate off-target regions. Our results showed, for the first time, a reduced susceptibility to Phytophtora infestans in pmr4 tomato mutants confirming the role of KO PMR4 in providing broad-spectrum protection against pathogens. 相似文献
8.
9.
Evgeny Grigoriev Anastasia V. Ponasenko Anna V. Sinitskaya Artem A. Ivkin Roman A. Kornelyuk 《International journal of molecular sciences》2022,23(23)
Assess the level of mitochondrial DNA depending on the presence of multiple organ failure in patients after heart surgery. The study included 60 patients who underwent surgical treatment of valvular heart disease using cardiopulmonary bypass. Uncomplicated patients were included in the 1st group (n = 30), patients with complications and multiple organ failure (MOF) were included in the 2nd group (n = 30). Serum mtDNA levels were determined by quantitative real-time polymerase chain reaction with fluorescent dyes. Mitochondrial DNA gene expression did not differ between group before surgery. Immediately after the intervention, cytochrome B gene expression was higher in the group with MOF, and it remained high during entire follow-up period. A similar trend was observed in cytochrome oxidase gene expression. Increased NADH levels of gene expressions during the first postoperative day were noted in both groups, the expression showed tendency to increase on the third postoperative day. mtDNA gene expression in the “MOF present” group remained at a higher level compared with the group without complications. A positive correlation was reveled between the severity of MOF according to SOFA score and the level of mtDNA (r = 0.45; p = 0.028) for the end-point “First day”. The ROC analysis showed that mtDNA circulating in plasma (AUC = 0.605) can be a predictor of MOF development. The level of mtDNA significantly increases in case of MOF, irrespective of its cause. (2) The expression of mtDNA genes correlates with the level of MOF severity on the SOFA score. 相似文献
10.
Aleksandra Owczarek-Januszkiewicz Anna Magiera Monika Anna Olszewska 《International journal of molecular sciences》2022,23(23)
Quercetin and its glycosides, such as isoquercitrin or rutin, are among the most ubiquitous flavonoids present in plants. They possess numerous health-promoting properties, whose applicability is, however, limited by poor water solubility and absorption issues. Enzymatically modified isoquercitrin (EMIQ) is an isoquercitrin derivative obtained from rutin via enzymatic transformations that greatly enhance its bioavailability. Due to advantageous reports on its safety and bioactivity, EMIQ is currently gaining importance as a food additive and a constituent of dietary supplements. This review summarizes the thus-far-conducted investigations into the metabolism, toxicity, biological properties, and molecular mechanisms of EMIQ and presents a comprehensive characterization of this valuable substance, which might represent the future of flavonoid supplementation. 相似文献