全文获取类型
收费全文 | 2768篇 |
免费 | 341篇 |
国内免费 | 144篇 |
专业分类
电工技术 | 66篇 |
综合类 | 103篇 |
化学工业 | 601篇 |
金属工艺 | 35篇 |
机械仪表 | 126篇 |
建筑科学 | 276篇 |
矿业工程 | 5篇 |
能源动力 | 5篇 |
轻工业 | 416篇 |
水利工程 | 12篇 |
石油天然气 | 10篇 |
武器工业 | 1篇 |
无线电 | 172篇 |
一般工业技术 | 344篇 |
冶金工业 | 586篇 |
原子能技术 | 39篇 |
自动化技术 | 456篇 |
出版年
2024年 | 9篇 |
2023年 | 91篇 |
2022年 | 94篇 |
2021年 | 410篇 |
2020年 | 173篇 |
2019年 | 132篇 |
2018年 | 120篇 |
2017年 | 116篇 |
2016年 | 118篇 |
2015年 | 116篇 |
2014年 | 175篇 |
2013年 | 127篇 |
2012年 | 151篇 |
2011年 | 195篇 |
2010年 | 134篇 |
2009年 | 130篇 |
2008年 | 119篇 |
2007年 | 114篇 |
2006年 | 96篇 |
2005年 | 95篇 |
2004年 | 84篇 |
2003年 | 74篇 |
2002年 | 59篇 |
2001年 | 52篇 |
2000年 | 16篇 |
1999年 | 25篇 |
1998年 | 18篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 15篇 |
1994年 | 21篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1979年 | 6篇 |
1966年 | 5篇 |
1965年 | 5篇 |
1964年 | 6篇 |
1960年 | 5篇 |
1959年 | 5篇 |
1958年 | 4篇 |
1957年 | 6篇 |
1956年 | 3篇 |
排序方式: 共有3253条查询结果,搜索用时 15 毫秒
1.
Virginia Veronica Visconti Ida Cariati Simona Fittipaldi Riccardo Iundusi Elena Gasbarra Umberto Tarantino Annalisa Botta 《International journal of molecular sciences》2021,22(8)
DNA methylation is one of the most studied epigenetic mechanisms that play a pivotal role in regulating gene expression. The epigenetic component is strongly involved in aging-bone diseases, such as osteoporosis and osteoarthritis. Both are complex multi-factorial late-onset disorders that represent a globally widespread health problem, highlighting a crucial point of investigations in many scientific studies. In recent years, new findings on the role of DNA methylation in the pathogenesis of aging-bone diseases have emerged. The aim of this systematic review is to update knowledge in the field of DNA methylation associated with osteoporosis and osteoarthritis, focusing on the specific tissues involved in both pathological conditions. 相似文献
2.
针对呼吸道系统疾病与大气 PM2:5、 SO2 浓度序列的相关性特征, 应用多重分形消除趋势波动分析法
(MF-DCCA), 对张家界市永定区呼吸道系统疾病患病人数与大气 PM2:5、 SO2 浓度序列进行了研究。结果发现该地区
呼吸道系统疾病患病人数与大气 PM2:5、 SO2 浓度的相关性具有长期持续特征和多重分形特征。随后对它们相关性
多重分形特征的动力来源进行了分析, 通过随机重排和相位随机处理, 结果表明在不同时间尺度上的长期持续性影响
是其主要动力来源。进一步研究发现该地区呼吸道系统疾病与大气 PM2:5、 SO2 浓度序列的相关性在四个季节均具
有长期持续性的多重分形特征, 且夏季多重分形特征相对强于其他季节。 相似文献
3.
Gaowa Bai Daisuke Furushima Toshiro Niki Takashi Matsuba Yosuke Maeda Atsushi Takahashi Toshio Hattori Yugo Ashino 《International journal of molecular sciences》2021,22(9)
Numbers of patients with coronavirus disease 2019 (COVID-19) have increased rapidly worldwide. Plasma levels of full-length galectin-9 (FL-Gal9) and osteopontin (FL-OPN) as well as their truncated forms (Tr-Gal9, Ud-OPN, respectively), are representative inflammatory biomarkers. Here, we measured FL-Gal9, FL-OPN, Tr-Gal9, and Ud-OPN in 94 plasma samples obtained from 23 COVID-19-infected patients with mild clinical symptoms (CV), 25 COVID-19 patients associated with pneumonia (CP), and 14 patients with bacterial infection (ID). The four proteins were significantly elevated in the CP group when compared with healthy individuals. ROC analysis between the CV and CP groups showed that C-reactive protein had the highest ability to differentiate, followed by Tr-Gal9 and ferritin. Spearman’s correlation analysis showed that Tr-Gal9 and Ud-OPN but not FL-Gal9 and FL-OPN, had a significant association with laboratory markers for lung function, inflammation, coagulopathy, and kidney function in CP patients. CP patients treated with tocilizumab had reduced levels of FL-Gal9, Tr-Gal9, and Ud-OPN. It was suggested that OPN is cleaved by interleukin-6-dependent proteases. These findings suggest that the cleaved forms of OPN and galectin-9 can be used to monitor the severity of pathological inflammation and the therapeutic effects of tocilizumab in CP patients. 相似文献
4.
Sedra Alabed Heping Zhou Ilker K. Sariyer Sulie L. Chang 《International journal of molecular sciences》2021,22(9)
The deposition of amyloid-beta (Aβ) through the cleavage of amyloid-beta precursor protein (APP) is a biomarker of Alzheimer’s disease (AD). This study used QIAGEN Ingenuity Pathway Analysis (IPA) to conduct meta-analysis on the molecular mechanisms by which methamphetamine (METH) impacts AD through modulating the expression of APP. All the molecules affected by METH and APP were collected from the QIAGEN Knowledge Base (QKB); 78 overlapping molecules were identified. Upon simulation of METH exposure using the “Molecule Activity Predictor” feature, eight molecules were found to be affected by METH and exhibited activation relationships on APP expression at a confidence of p = 0.000453 (Z-score = 3.51, two-tailed). Core Analysis of these eight molecules identified High Mobility Group Box protein 1 (HMGB1) signaling pathway among the top 5 canonical pathways with most overlap with the 8-molecule dataset. Simulated METH exposure increased APP expression through HMGB1 at a confidence of p < 0.00001 (Z-score = 7.64, two-tailed). HMGB1 is a pathogenic hallmark in AD progression. It not only increases the production of inflammatory mediators, but also mediates the disruption of the blood-brain barrier. Our analyses suggest the involvement of HMGB1 signaling pathway in METH-induced modulation of APP as a potential casual factor of AD. 相似文献
5.
Dr. Ala Jo Mingi Kim Dr. Jong In Kim Jaeyoung Ha Yoon Soo Hwang Hyunsung Nam Dr. Injae Hwang Dr. Jae Bum Kim Prof. Seung Bum Park 《ChemMedChem》2021,16(7):1104-1115
Obesity has become a pandemic that threatens the quality of life and discovering novel therapeutic agents that can reverse obesity and obesity-related metabolic disorders are necessary. Here, we aimed to identify new anti-obesity agents using a phenotype-based approach. We performed image-based high-content screening with a fluorogenic bioprobe (SF44), which visualizes cellular lipid droplets (LDs), to identify initial hit compounds. A structure-activity relationship study led us to yield a bioactive compound SB1501, which reduces cellular LDs in 3T3-L1 adipocytes without cytotoxicity. SB1501 induced the expression of gene products that regulate mitochondrial biogenesis and fatty acid oxidation in 3T3-L1 adipocytes. Daily treatment with SB1501 improved the metabolic states of db/db mice by reducing body fat mass, adipose tissue mass, food intake, and increasing glucose tolerance. The anti-obesity effect of SB1501 may result from perturbation of the PGC-1α–UCP1 regulatory axis in inguinal white adipose tissue and brown adipose tissue. These data suggest the therapeutic potential of SB1501 as an anti-obesity agent via modulating mitochondrial activities. 相似文献
6.
Agnieszka Rybarczyk-Kasiuchnicz Rodryg Ramlau Katarzyna Stencel 《International journal of molecular sciences》2021,22(2)
Lung cancer is one of the most common malignant neoplasms. As a result of the disease’s progression, patients may develop metastases to the central nervous system. The prognosis in this location is unfavorable; untreated metastatic lesions may lead to death within one to two months. Existing therapies—neurosurgery and radiation therapy—do not improve the prognosis for every patient. The discovery of Epidermal Growth Factor Receptor (EGFR)—activating mutations and Anaplastic Lymphoma Kinase (ALK) rearrangements in patients with non-small cell lung adenocarcinoma has allowed for the introduction of small-molecule tyrosine kinase inhibitors to the treatment of advanced-stage patients. The Epidermal Growth Factor Receptor (EGFR) is a transmembrane protein with tyrosine kinase-dependent activity. EGFR is present in membranes of all epithelial cells. In physiological conditions, it plays an important role in the process of cell growth and proliferation. Binding the ligand to the EGFR causes its dimerization and the activation of the intracellular signaling cascade. Signal transduction involves the activation of MAPK, AKT, and JNK, resulting in DNA synthesis and cell proliferation. In cancer cells, binding the ligand to the EGFR also leads to its dimerization and transduction of the signal to the cell interior. It has been demonstrated that activating mutations in the gene for EGFR-exon19 (deletion), L858R point mutation in exon 21, and mutation in exon 20 results in cancer cell proliferation. Continuous stimulation of the receptor inhibits apoptosis, stimulates invasion, intensifies angiogenesis, and facilitates the formation of distant metastases. As a consequence, the cancer progresses. These activating gene mutations for the EGFR are present in 10–20% of lung adenocarcinomas. Approximately 3–7% of patients with lung adenocarcinoma have the echinoderm microtubule-associated protein-like 4 (EML4)/ALK fusion gene. The fusion of the two genes EML4 and ALK results in a fusion gene that activates the intracellular signaling pathway, stimulates the proliferation of tumor cells, and inhibits apoptosis. A new group of drugs—small-molecule tyrosine kinase inhibitors—has been developed; the first generation includes gefitinib and erlotinib and the ALK inhibitor crizotinib. These drugs reversibly block the EGFR by stopping the signal transmission to the cell. The second-generation tyrosine kinase inhibitor (TKI) afatinib or ALK inhibitor alectinib block the receptor irreversibly. Clinical trials with TKI in patients with non-small cell lung adenocarcinoma with central nervous system (CNS) metastases have shown prolonged, progression-free survival, a high percentage of objective responses, and improved quality of life. Resistance to treatment with this group of drugs emerging during TKI therapy is the basis for the detection of resistance mutations. The T790M mutation, present in exon 20 of the EGFR gene, is detected in patients treated with first- and second-generation TKI and is overcome by Osimertinib, a third-generation TKI. The I117N resistance mutation in patients with the ALK mutation treated with alectinib is overcome by ceritinib. In this way, sequential therapy ensures the continuity of treatment. In patients with CNS metastases, attempts are made to simultaneously administer radiation therapy and tyrosine kinase inhibitors. Patients with lung adenocarcinoma with CNS metastases, without activating EGFR mutation and without ALK rearrangement, benefit from immunotherapy. This therapeutic option blocks the PD-1 receptor on the surface of T or B lymphocytes or PD-L1 located on cancer cells with an applicable antibody. Based on clinical trials, pembrolizumab and all antibodies are included in the treatment of non-small cell lung carcinoma with CNS metastases. 相似文献
7.
8.
Inflammation, an innate immune response that prevents cellular damage caused by pathogens, consists of two successive mechanisms, namely priming and triggering. While priming is an inflammation-preparation step, triggering is an inflammation-activation step, and the central feature of triggering is the activation of inflammasomes and intracellular inflammatory protein complexes. Flavonoids are natural phenolic compounds predominantly present in plants, fruits, and vegetables and are known to possess strong anti-inflammatory activities. The anti-inflammatory activity of flavonoids has long been demonstrated, with the main focus on the priming mechanisms, while increasing numbers of recent studies have redirected the research focus on the triggering step, and studies have reported that flavonoids inhibit inflammatory responses and diseases by targeting inflammasome activation. Rheumatic diseases are systemic inflammatory and autoimmune diseases that primarily affect joints and connective tissues, and they are associated with numerous deleterious effects. Here, we discuss the emerging literature on the ameliorative role of flavonoids targeting inflammasome activation in inflammatory rheumatic diseases. 相似文献
9.
J. Thomas BRENNA 《粮油食品科技》2022,30(3):7-15
人体大脑和身体的发育,需要从食物中摄取均衡的营养物质。人类大脑是区分人类和其他动物的特征。食物中的必需脂肪酸是机体组织结构和功能的必要组成部分。Omega-6(O6)亚油酸(LA6)是皮肤组织的组成成分,且是炎症、血栓形成、免疫和其他信号分子的前体;Omega-3(O3)α-亚麻酸(ALA3),特别是其长链代谢产物——二十二碳六烯酸(DHA3),是大脑、视网膜和部分神经组织中的关键组分。从富含LA6脂肪酸(缺乏O3脂肪酸)的植物籽中提取出的廉价而优质油脂,是20世纪的西方国家食品工业生产的主要脂肪来源。在代谢通路中,高浓度的LA6脂肪酸可拮抗O3脂肪酸代谢,造成O3脂肪酸不足,因此,在给怀孕动物的饲料中,只提供富含LA6但缺乏O3脂肪酸的油脂作为唯一的脂肪来源,会导致幼崽大脑发育不良。过去20~30年的研究表明,低含量LA6且含DHA3的油脂可改善大脑的功能。近年来的研究较多集中在营养因素对大脑发育的影响,最新研究数据表明,脂肪酸平衡对营养不良儿童的大脑发育尤为重要。世界卫生组织(WHO)越来越重视大脑的营养健康,通过其下属的食品法典委员会,建议用于治疗严重急性营养不良儿童的即食治疗食品中,使用含有均衡脂肪酸组成/构成的脂肪。同样,脂肪酸均衡对老年人可能也很重要。目前,业界已经有了调整油脂成分的方法,以确保脂肪酸均衡,从而维持人体整个生命周期的大脑健康。 相似文献
10.