全文获取类型
收费全文 | 10798篇 |
免费 | 1226篇 |
国内免费 | 676篇 |
专业分类
电工技术 | 258篇 |
技术理论 | 2篇 |
综合类 | 1475篇 |
化学工业 | 1914篇 |
金属工艺 | 155篇 |
机械仪表 | 459篇 |
建筑科学 | 1134篇 |
矿业工程 | 194篇 |
能源动力 | 86篇 |
轻工业 | 874篇 |
水利工程 | 329篇 |
石油天然气 | 91篇 |
武器工业 | 46篇 |
无线电 | 685篇 |
一般工业技术 | 897篇 |
冶金工业 | 1340篇 |
原子能技术 | 112篇 |
自动化技术 | 2649篇 |
出版年
2024年 | 52篇 |
2023年 | 180篇 |
2022年 | 517篇 |
2021年 | 550篇 |
2020年 | 334篇 |
2019年 | 328篇 |
2018年 | 299篇 |
2017年 | 356篇 |
2016年 | 405篇 |
2015年 | 456篇 |
2014年 | 637篇 |
2013年 | 718篇 |
2012年 | 661篇 |
2011年 | 670篇 |
2010年 | 620篇 |
2009年 | 590篇 |
2008年 | 627篇 |
2007年 | 688篇 |
2006年 | 682篇 |
2005年 | 625篇 |
2004年 | 486篇 |
2003年 | 413篇 |
2002年 | 288篇 |
2001年 | 255篇 |
2000年 | 153篇 |
1999年 | 124篇 |
1998年 | 102篇 |
1997年 | 82篇 |
1996年 | 66篇 |
1995年 | 55篇 |
1994年 | 52篇 |
1993年 | 56篇 |
1992年 | 41篇 |
1991年 | 36篇 |
1990年 | 36篇 |
1989年 | 30篇 |
1988年 | 25篇 |
1987年 | 23篇 |
1986年 | 34篇 |
1985年 | 28篇 |
1984年 | 30篇 |
1983年 | 28篇 |
1982年 | 17篇 |
1981年 | 19篇 |
1959年 | 16篇 |
1958年 | 14篇 |
1957年 | 22篇 |
1956年 | 16篇 |
1955年 | 25篇 |
1954年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
51.
Shuntaro Machida Katsuichi Saito Mamoru Nishimoto Motomitsu Kitaoka 《Journal of Applied Glycoscience》2022,69(2):15
Lacto-N-biose I (LNB) is supposed to represent the bifidus factor in human milk oligosaccharides, and can be practically produced from sucrose and GlcNAc using four bifidobacterial enzymes, 1,3-β-galactosyl-N-acetylhexosamine phosphorylase, sucrose phosphorylase, UDP-glucose-hexose 1-phosphate uridylyltransferase, and UDP-glucose 4-epimerase, recombinantly produced by Escherichia coli. Here the production of LNB by the same enzymatic method without using genetically modified enzymes to consider the use of LNB for a food ingredient was reported. All four enzymes were produced as the intracellular enzymes of Bifidobacterium strains. The mixture of the crude extracts contained all four enzymes, with other enzymes interfering with the LNB production, namely, phosphoglucomutase, fructose 6-phosphate phosphoketolase, and glycogen phosphorylase. The first two interfering enzymes were selectively inactivated by heat treatment at 47 °C for 1 h in the presence of pancreatin, and glycogen phosphorylase was disabled by hydrolyzing its possible acceptor molecules using glucoamylase. Finally, 91 % of GlcNAc was converted into LNB in the 100-mL reaction mixture containing 300 mM GlcNAc. 相似文献
52.
53.
54.
为满足人机系统概率风险评估的需要,提出一种人为差错概率量化方法。分析技能、规则和知识为基础
(skill, rule and knowledge-based,SRK)框架和行为模式的确定方法Hanaman 决策树法,指出在确定行为模式的过程
中考虑行为模式影响因素的不确定性是必要的;使用模糊逻辑方法处理行为模式各个影响因素的不确定性,根据
Hanaman 决策树构建模糊推理规则,利用系统人为行为可靠性程序(systematic human action reliability procedure,
SHARP)方法所提供的人为差错概率区间确定人为差错概率的隶属度函数。结果表明:该方法考虑了任务场景的不确
定性,可以得到人为差错概率的精确值,满足人机系统概率风险评估的需要。 相似文献
55.
为提高武器装备的操作安全性,提出一种人为差错辨识方法。介绍人为差错辨识的基本概念和现有方法,
指出现有方法存在的不足,提出基于操作规程和人机界面的人为差错辨识方法;通过分析操作规程建立人为差错模
式的包络,通过分析人机界面基本特征筛选出有效的人为差错模式。结果表明:该方法可提高人为差错辨识结果的
有效性,为人为差错管理提供指导。 相似文献
56.
Barbara Sita Mihaela Bobi-Rasonja Goran Mrak Sara Trnski Magdalena Krbot Skori Darko Orekovi Vinka Knezovi
eljka Petelin Gade Zdravko Petanjek Goran imi Danijela Kolenc Nataa Jovanov Miloevi 《International journal of molecular sciences》2022,23(15)
The extracellular matrix (ECM) is an important regulator of excitability and synaptic plasticity, especially in its highly condensed form, the perineuronal nets (PNN). In patients with drug-resistant mesial temporal lobe epilepsy (MTLE), hippocampal sclerosis type 1 (HS1) is the most common histopathological finding. This study aimed to evaluate the ECM profile of HS1 in surgically treated drug-resistant patients with MTLE in correlation to clinical findings. Hippocampal sections were immunohistochemically stained for aggrecan, neurocan, versican, chondroitin-sulfate (CS56), fibronectin, Wisteria floribunda agglutinin (WFA), a nuclear neuronal marker (NeuN), parvalbumin (PV), and glial-fibrillary-acidic-protein (GFAP). In HS1, besides the reduced number of neurons and astrogliosis, we found a significantly changed expression pattern of versican, neurocan, aggrecan, WFA-specific glycosylation, and a reduced number of PNNs. Patients with a lower number of epileptic episodes had a less intense diffuse WFA staining in Cornu Ammonis (CA) fields. Our findings suggest that PNN reduction, changed ECM protein, and glycosylation expression pattern in HS1 might be involved in the pathogenesis and persistence of drug-resistant MTLE by contributing to the increase of CA pyramidal neurons’ excitability. This research corroborates the validity of ECM molecules and their modulators as a potential target for the development of new therapeutic approaches to drug-resistant epilepsy. 相似文献
57.
Head and neck squamous cell carcinomas (HNSCCs) are the sixth most common cancers worldwide. More than half of patients with HNSCC eventually experience disease recurrence and/or metastasis, which can threaten their long-term survival. HNSCCs located in the oral cavity and larynx are usually associated with tobacco and/or alcohol use, whereas human papillomavirus (HPV) infection, particularly HPV16 infection, is increasingly recognized as a cause of oropharyngeal HNSCC. Despite clinical, histologic, and molecular differences between HPV-positive and HPV-negative HNSCCs, current treatment approaches are the same. For recurrent disease, these strategies include chemotherapy, immunotherapy with PD-1-inhibitors, or a monoclonal antibody, cetuximab, that targets epidermal growth factor; these therapies can be administered either as single agents or in combination. However, these treatment strategies carry a high risk of toxic side effects; therefore, more effective and less toxic treatments are needed. The landscape of HNSCC therapy is changing significantly; numerous clinical trials are underway to test novel therapeutic options like adaptive cellular therapy, antibody-drug conjugates, new targeted therapy agents, novel immunotherapy combinations, and therapeutic vaccines. This review helps in understanding the various developments in HNSCC therapy and sheds light on the path ahead in terms of further research in this field. 相似文献
58.
Nathalie M. Malewicz Zahra Rattray Sebastian Oeck Sebastian Jung Vicente Escamilla-Rivera Zeming Chen Xiangjun Tang Jiangbing Zhou Robert H. LaMotte 《International journal of molecular sciences》2022,23(9)
Background: Capsaicin, the hot pepper agent, produces burning followed by desensitization. To treat localized itch or pain with minimal burning, low capsaicin concentrations can be repeatedly applied. We hypothesized that alternatively controlled release of capsaicin from poly(lactic-co-glycolic acid) (PLGA) nanoparticles desensitizes superficially terminating nociceptors, reducing burning. Methods: Capsaicin-loaded PLGA nanoparticles were prepared (single-emulsion solvent evaporation) and characterized (size, morphology, capsaicin loading, encapsulation efficiency, in vitro release profile). Capsaicin-PLGA nanoparticles were applied to murine skin and evaluated in healthy human participants (n = 21) for 4 days under blinded conditions, and itch and nociceptive sensations evoked by mechanical, heat stimuli and pruritogens cowhage, β-alanine, BAM8-22 and histamine were evaluated. Results: Nanoparticles (loading: 58 µg capsaicin/mg) released in vitro 23% capsaicin within the first hour and had complete release at 72 h. In mice, 24 h post-application Capsaicin-PLGA nanoparticles penetrated the dermis and led to decreased nociceptive behavioral responses to heat and mechanical stimulation (desensitization). Application in humans produced a weak to moderate burning, dissipating after 3 h. A loss of heat pain up to 2 weeks was observed. After capsaicin nanoparticles, itch and nociceptive sensations were reduced in response to pruritogens cowhage, β-alanine or BAM8-22, but were normal to histamine. Conclusions: Capsaicin nanoparticles could be useful in reducing pain and itch associated with pruritic diseases that are histamine-independent. 相似文献
59.
Andrea Auditore Sabrina Gensberger-Reigl Monika Pischetsrieder 《International journal of molecular sciences》2022,23(9)
3,4-Dideoxyglucosone-3-ene (3,4-DGE) is a glucose degradation product present in processed foods and medicinal products. Additionally, its constant formation from 3-deoxyglucosone in plasma has been suggested. Due to its α,β-unsaturated dicarbonyl moiety, 3,4-DGE is highly reactive and has shown harmful effects in vitro. Here, we investigated the impact of major components of the human blood circulatory system on 3,4-DGE in vitro. Under physiological conditions, plasma concentrations of human serum albumin (HSA) reacted efficiently with 3,4-DGE, resulting in only 8.5% of the initial 3,4-DGE concentration after seven hours (vs. 83.4% without HSA, p < 0.001). Thereby, accessible thiol groups were reduced from 0.121 to 0.064 mol/mol HSA, whereas ketoprofen binding and esterase-like activity of HSA were not affected. Plasma concentrations of glutathione (GSH) reacted immediately and completely with 3,4-DGE, leading to two stereoisomeric adducts. Plasma concentrations of immunoglobulin G (IgG) bound to 3,4-DGE to a lower extent, resulting in 62.6% 3,4-DGE after seven hours (vs. 82.2% in the control, p < 0.01). Immobilized human collagen type IV did not alter 3,4-DGE concentrations. The results indicated that particularly HSA, GSH, and IgG readily scavenge 3,4-DGE after its appearance in the blood stream, which may be associated with a reduced antioxidative and cytoprotective activity for the living cells and, thus, the human organism by blocking free thiol groups. 相似文献
60.
Anna Jagusiak Katarzyna Chopa Grzegorz Zemanek Izabela Kocik Pawe Skorek Barbara Stopa 《International journal of molecular sciences》2022,23(9)
Congo red (CR) type self–assembled ribbon–like structures (SRLS) were previously shown to interact with some proteins, including albumin. SRLS also complex with some drugs with a flat, ring–shaped structure with aromatic characteristics, intercalating them into their ribbon structure. The combination of interaction with proteins and drug binding by SRLS enables the use of such systems for immunotargeting. It is especially interesting in the case of chemotherapeutic agents. The present experiments aimed to show that the model carrier system composed of supramolecular albumin and Congo red efficiently binds doxorubicin (Dox) and that the drug can be released at reduced pH. The presented results come from the studies on such complexes differing in the molar ratio of CR to Dox. The following methods were used for the analysis: electrophoresis, dialysis, gel filtration, spectral analysis, and analysis of the size of the hydrodynamic radius using the dynamic light scattering method (DLS). The applied methods confirmed the formation of the CR–Dox complex, with large dimensions and changed properties compared with free CR. The presented results show that albumin binds both CR and its complex with Dox. Various CR–Dox molar ratios, 5:1, 2:1, and 1:1, were analyzed. The confirmation of the possibility of releasing the drug from the carriers thus formed was also obtained. The presented research is important due to the search for optimal solutions for the use of SRLS in drug immunotargeting, with particular emphasis on chemotherapeutic agents. 相似文献