全文获取类型
收费全文 | 151326篇 |
免费 | 13130篇 |
国内免费 | 7379篇 |
专业分类
电工技术 | 8686篇 |
综合类 | 8764篇 |
化学工业 | 35126篇 |
金属工艺 | 12105篇 |
机械仪表 | 7019篇 |
建筑科学 | 7868篇 |
矿业工程 | 3408篇 |
能源动力 | 18138篇 |
轻工业 | 10045篇 |
水利工程 | 1958篇 |
石油天然气 | 6802篇 |
武器工业 | 1430篇 |
无线电 | 12796篇 |
一般工业技术 | 19105篇 |
冶金工业 | 8525篇 |
原子能技术 | 3609篇 |
自动化技术 | 6451篇 |
出版年
2024年 | 483篇 |
2023年 | 2560篇 |
2022年 | 4648篇 |
2021年 | 6175篇 |
2020年 | 5330篇 |
2019年 | 4809篇 |
2018年 | 4342篇 |
2017年 | 5324篇 |
2016年 | 5431篇 |
2015年 | 5365篇 |
2014年 | 8515篇 |
2013年 | 9471篇 |
2012年 | 10203篇 |
2011年 | 12137篇 |
2010年 | 8713篇 |
2009年 | 8644篇 |
2008年 | 7762篇 |
2007年 | 9160篇 |
2006年 | 8384篇 |
2005年 | 6945篇 |
2004年 | 6065篇 |
2003年 | 5242篇 |
2002年 | 4475篇 |
2001年 | 3853篇 |
2000年 | 3294篇 |
1999年 | 2566篇 |
1998年 | 2119篇 |
1997年 | 1783篇 |
1996年 | 1554篇 |
1995年 | 1194篇 |
1994年 | 1088篇 |
1993年 | 757篇 |
1992年 | 769篇 |
1991年 | 590篇 |
1990年 | 469篇 |
1989年 | 339篇 |
1988年 | 258篇 |
1987年 | 157篇 |
1986年 | 143篇 |
1985年 | 154篇 |
1984年 | 124篇 |
1983年 | 80篇 |
1982年 | 97篇 |
1981年 | 50篇 |
1980年 | 59篇 |
1979年 | 41篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1959年 | 27篇 |
1951年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
991.
Yuning Lou Yajuan Dong Xiaoyong Wang Feirong Gong Min Zhao Zongming Rong 《Journal of surfactants and detergents》2021,24(1):3-13
Two generations of novel linear-dendritic carboxylate surfactants C18-G1-(COONa)2 and C18-G2-(COONa)4 have been synthesized by the divergent method and their structures are characterized by 1H Nuclear Magnetic Resonance and Infrared analysis. The electrical conductivity measurement is used to measure the Krafft temperatures of C18-G1-(COONa)2 and C18-G2-(COONa)4, which are much smaller than those of the corresponding conventional surfactant sodium stearate. The markedly enhanced solubility of two linear-dendritic surfactants is ascribed to the high hydrophilicity of surfactant headgroups induced by the carboxylate and ester groups. The critical micelle concentration (CMC) values obtained from both the electrical conductivity and surface tension measurements indicate that the micellizations of linear-dendritic surfactants become favorable with the increase in the number of the surfactant headgroup. However, the surface activity parameters including the surface tension at the CMC, maximum surface excess, and minimum surface area reveal that C18-G1-(COONa)2 exhibits greater efficiency in absorbing at the air/water interface compared to C18-G2-(COONa)4, owing to their different steric repulsions of the surfactant headgroups. In addition, C18-G1-(COONa)2 and C18-G2-(COONa)4 have higher emulsifying ability than the conventional surfactants sodium stearate and sodium octadecyl sulfate. 相似文献
992.
993.
Giuseppina Emanuela Grieco Noemi Brusco Giada Licata Daniela Fignani Caterina Formichi Laura Nigi Guido Sebastiani Francesco Dotta 《International journal of molecular sciences》2021,22(2)
Diabetes mellitus is a group of heterogeneous metabolic disorders characterized by chronic hyperglycaemia mainly due to pancreatic β cell death and/or dysfunction, caused by several types of stress such as glucotoxicity, lipotoxicity and inflammation. Different patho-physiological mechanisms driving β cell response to these stresses are tightly regulated by microRNAs (miRNAs), a class of negative regulators of gene expression, involved in pathogenic mechanisms occurring in diabetes and in its complications. In this review, we aim to shed light on the most important miRNAs regulating the maintenance and the robustness of β cell identity, as well as on those miRNAs involved in the pathogenesis of the two main forms of diabetes mellitus, i.e., type 1 and type 2 diabetes. Additionally, we acknowledge that the understanding of miRNAs-regulated molecular mechanisms is fundamental in order to develop specific and effective strategies based on miRNAs as therapeutic targets, employing innovative molecules. 相似文献
994.
Magdalena Misiura Tomasz Guszczyn Ilona Oscilowska Weronika Baszanowska Jerzy Palka Wojciech Miltyk 《International journal of molecular sciences》2021,22(2)
Although the role of platelet-rich plasma (PRP) in tissue regeneration has been confirmed in many studies, the mechanism of this process is still not fully understood. Human keratinocytes (HaCaT) cells were used as an experimental model for studies on the effects of PRP on cell proliferation, migration, collagen biosynthesis, prolidase activity, and its expression and anabolic signaling. The activation of epidermal growth factor receptor (EGFR), β1-integrin, and insulin-like growth factor-1 receptor (IGF-1R) by PRP were investigated by western blot and immunocytochemistry. It has been found that PRP induced keratinocytes migration and proliferation through activation of cell cycle progression and EGFR downstream signaling. Similar biological effects were achieved by an addition to the culture medium of prolidase (PEPD), a ligand of EGFR (PRP is a rich source of PEPD–2 ng/mL). PRP-dependent stimulation of collagen biosynthesis was accompanied by an increase in the expression of NF-κβ, IGF-1R-downstream signaling proteins, and PEPD activity. The data suggest that PRP activates a complex of growth factors and adhesion receptors that stimulate cell proliferation, migration, and collagen biosynthesis. PRP induces PEPD-dependent human keratinocyte proliferation through activation of the EGFR receptor. Our study provides a novel mechanism of PRP-dependent wound healing. 相似文献
995.
Hiroko Ishii Maram H. Zahra Atushi Takayanagi Masaharu Seno 《International journal of molecular sciences》2021,22(4)
Cripto-1 is a member of the EGF-CFC/FRL1/Cryptic family and is involved in embryonic development and carcinogenesis. We designed a novel anti-Cripto-1 artificial antibody and assessed the recognition to the antigen and the potential to suppress the growth of cancer stem cells. First, single chain antibody clones were isolated by bio-panning with the affinity to recombinant Cripto-1 protein from our original phage-display library. Then, the variable regions of heavy chain VH and light chain VL in each clone were fused to constant regions of heavy chain CH and light chain CL regions respectively. These fused genes were expressed in ExpiCHO-S cells to produce artificial humanized antibodies against Cripto-1. After evaluation of the expression levels, one clone was selected and the anti-Cripto-1 antibody was produced and purified. The purified antibody showed affinity to recombinant Cripto-1 at 1.1 pmol and immunoreactivity to cancer tissues and cell lines. The antibody was available to detect the immunoreactivity in tissue microarrays of malignant tumors as well as in Cripto-1 overexpressing cells. Simultaneously, the antibody exhibited the potential to suppress the growth of human colon cancer derived GEO cells overexpressing Cripto-1 with IC50 at approximately 110 nM. The artificially humanized antibody is proposed to be a good candidate to target cancer cells overexpressing Cripto-1. 相似文献
996.
Barbora Peltanova Marketa Liskova Jaromir Gumulec Martina Raudenska Hana Holcova Polanska Tomas Vaculovic David Kalfert Marek Grega Jan Plzak Jan Betka Michal Masarik 《International journal of molecular sciences》2021,22(4)
Cancer-associated fibroblasts (CAFs) are one of the most abundant and critical components of the tumor stroma. CAFs can impact many important steps of cancerogenesis and may also influence treatment resistance. Some of these effects need the direct contact of CAFs and cancer cells, while some involve paracrine signals. In this study, we investigated the ability of head and neck squamous cell carcinomas (HNSCC) patient-derived CAFs to promote or inhibit the colony-forming ability of HNSCC cells. The effect of cisplatin on this promoting or inhibiting influence was also studied. The subsequent analysis focused on changes in the expression of genes associated with cancer progression. We found that cisplatin response in model HNSCC cancer cells was modified by coculture with CAFs, was CAF-specific, and different patient-derived CAFs had a different “sensitizing ratio”. Increased expression of VEGFA, PGE2S, COX2, EGFR, and NANOG in cancer cells was characteristic for the increase of resistance. On the other hand, CCL2 expression was associated with sensitizing effect. Significantly higher amounts of cisplatin were found in CAFs derived from patients who subsequently experienced a recurrence. In conclusion, our results showed that CAFs could promote and/or inhibit colony-forming capability and cisplatin resistance in HNSCC cells via paracrine effects and subsequent changes in gene expression of cancer-associated genes in cancer cells. 相似文献
997.
998.
Hantae Jo Sofia Brito Byeong Mun Kwak Sangkyu Park Mi-Gi Lee Bum-Ho Bin 《International journal of molecular sciences》2021,22(5)
Mesenchymal stem cells (MSCs) are multipotent stem cells derived from adult stem cells. Primary MSCs can be obtained from diverse sources, including bone marrow, adipose tissue, and umbilical cord blood. Recently, MSCs have been recognized as therapeutic agents for skin regeneration and rejuvenation. The skin can be damaged by wounds, caused by cutting or breaking of the tissue, and burns. Moreover, skin aging is a process that occurs naturally but can be worsened by environmental pollution, exposure to ultraviolet radiation, alcohol consumption, tobacco use, and undernourishment. MSCs have healing capacities that can be applied in damaged and aged skin. In skin regeneration, MSCs increase cell proliferation and neovascularization, and decrease inflammation in skin injury lesions. In skin rejuvenation, MSCs lead to production of collagen and elastic fibers, inhibition of metalloproteinase activation, and promote protection from ultraviolet radiation-induced senescence. In this review, we focus on how MSCs and MSC-derived molecules improve diseased and aged skin. Additionally, we emphasize that induced pluripotent stem cell (iPSC)-derived MSCs are potentially advanced MSCs, which are suitable for cell therapy. 相似文献
999.
Francisco J. Corpas Salvador Gonzlez-Gordo Jos M. Palma 《International journal of molecular sciences》2021,22(5)
The peroxisome is a single-membrane subcellular compartment present in almost all eukaryotic cells from simple protists and fungi to complex organisms such as higher plants and animals. Historically, the name of the peroxisome came from a subcellular structure that contained high levels of hydrogen peroxide (H2O2) and the antioxidant enzyme catalase, which indicated that this organelle had basically an oxidative metabolism. During the last 20 years, it has been shown that plant peroxisomes also contain nitric oxide (NO), a radical molecule than leads to a family of derived molecules designated as reactive nitrogen species (RNS). These reactive species can mediate post-translational modifications (PTMs) of proteins, such as S-nitrosation and tyrosine nitration, thus affecting their function. This review aims to provide a comprehensive overview of how NO could affect peroxisomal metabolism and its internal protein-protein interactions (PPIs). Remarkably, many of the identified NO-target proteins in plant peroxisomes are involved in the metabolism of reactive oxygen species (ROS), either in its generation or its scavenging. Therefore, it is proposed that NO is a molecule with signaling properties with the capacity to modulate the peroxisomal protein-protein network and consequently the peroxisomal functions, especially under adverse environmental conditions. 相似文献
1000.
Su-Min Baek Seoung-Woo Lee Tae-Un Kim Seong-Kyoon Choi Sungho Yun Won-Jae Lee Se-Hyeon Han Il-Hwa Hong Sang-Joon Park Tae-Hwan Kim Kyu-Shik Jeong Jin-Kyu Park 《International journal of molecular sciences》2021,22(5)
Senescence marker protein 30 (SMP30) is a cell survival factor playing an important role in vitamin C synthesis and antiapoptosis. Moreover, its cytoprotective role suggests a possibility to be related to cancer cell survival. Mammary carcinoma is a common cancer in both humans and animals. Because of its histopathological diversity, especially in the early stage, histopathological diagnosis may be complicated; therefore, a diagnostic marker is helpful for confirmation. The present study analyzed the expression pattern of SMP30 in mammary carcinoma in humans, dogs, and cats. Immunohistochemistry, immunofluorescence, and western blot analysis were used to investigate SMP30 expression patterns. The expression was specifically observed in neoplastic glandular epithelial cells. The expression increased with the malignancy of glandular epithelial cells with a highly proliferative status. However, SMP30 expression was low in normal mammary gland tissues or well-differentiated adenoma tissues. The patterns were consistently reproduced in canine primary mammary carcinoma cells and MCF-7 and MDA-MB-231 human carcinoma cell lines. This study provides useful information to understand SMP30 expression in various stages of mammary carcinoma and to suggest its utility as a pan-species diagnostic marker, thereby helping to establish strategies for diagnosing mammary carcinoma in several species. 相似文献