全文获取类型
收费全文 | 36426篇 |
免费 | 3500篇 |
国内免费 | 1820篇 |
专业分类
电工技术 | 2366篇 |
技术理论 | 2篇 |
综合类 | 2447篇 |
化学工业 | 6081篇 |
金属工艺 | 1867篇 |
机械仪表 | 2328篇 |
建筑科学 | 3423篇 |
矿业工程 | 970篇 |
能源动力 | 985篇 |
轻工业 | 3350篇 |
水利工程 | 688篇 |
石油天然气 | 1721篇 |
武器工业 | 274篇 |
无线电 | 4284篇 |
一般工业技术 | 4285篇 |
冶金工业 | 1391篇 |
原子能技术 | 517篇 |
自动化技术 | 4767篇 |
出版年
2024年 | 211篇 |
2023年 | 742篇 |
2022年 | 1444篇 |
2021年 | 1856篇 |
2020年 | 1309篇 |
2019年 | 1119篇 |
2018年 | 1199篇 |
2017年 | 1328篇 |
2016年 | 1189篇 |
2015年 | 1557篇 |
2014年 | 1923篇 |
2013年 | 2217篇 |
2012年 | 2498篇 |
2011年 | 2652篇 |
2010年 | 2417篇 |
2009年 | 2288篇 |
2008年 | 2102篇 |
2007年 | 1925篇 |
2006年 | 1823篇 |
2005年 | 1527篇 |
2004年 | 1011篇 |
2003年 | 924篇 |
2002年 | 888篇 |
2001年 | 782篇 |
2000年 | 734篇 |
1999年 | 759篇 |
1998年 | 520篇 |
1997年 | 516篇 |
1996年 | 493篇 |
1995年 | 401篇 |
1994年 | 328篇 |
1993年 | 222篇 |
1992年 | 173篇 |
1991年 | 123篇 |
1990年 | 90篇 |
1989年 | 88篇 |
1988年 | 70篇 |
1987年 | 46篇 |
1986年 | 40篇 |
1985年 | 24篇 |
1984年 | 14篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1962年 | 42篇 |
1961年 | 39篇 |
1960年 | 16篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Ning-Wei Lai Zhi-Chao Zheng Dan Hua Jiang Zhang Huan-Huan Chen Xin Ye Zeng-Rong Huang Jiuxin Guo Lin-Tong Yang Li-Song Chen 《International journal of molecular sciences》2022,23(10)
Low pH-induced alterations in gene expression profiles and organic acids (OA) and free amino acid (FAA) abundances were investigated in sweet orange [Citrus sinensis (L.) Osbeck cv. Xuegan] leaves. We identified 503 downregulated and 349 upregulated genes in low pH-treated leaves. Further analysis indicated that low pH impaired light reaction and carbon fixation in photosynthetic organisms, thereby lowering photosynthesis in leaves. Low pH reduced carbon and carbohydrate metabolisms, OA biosynthesis and ATP production in leaves. Low pH downregulated the biosynthesis of nitrogen compounds, proteins, and FAAs in leaves, which might be conducive to maintaining energy homeostasis during ATP deprivation. Low pH-treated leaves displayed some adaptive responses to phosphate starvation, including phosphate recycling, lipid remodeling, and phosphate transport, thus enhancing leaf acid-tolerance. Low pH upregulated the expression of some reactive oxygen species (ROS) and aldehyde detoxifying enzyme (peroxidase and superoxidase) genes and the concentrations of some antioxidants (L-tryptophan, L-proline, nicotinic acid, pantothenic acid, and pyroglutamic acid), but it impaired the pentose phosphate pathway and VE and secondary metabolite biosynthesis and downregulated the expression of some ROS and aldehyde detoxifying enzyme (ascorbate peroxidase, aldo-keto reductase, and 2-alkenal reductase) genes and the concentrations of some antioxidants (pyridoxine and γ-aminobutyric acid), thus disturbing the balance between production and detoxification of ROS and aldehydes and causing oxidative damage to leaves. 相似文献
72.
73.
74.
75.
Magdalene K. Ameka William N. Beavers Ciara M. Shaver Lorraine B. Ware Vern Eric Kerchberger Kelly Q. Schoenfelt Lili Sun Tatsuki Koyama Eric P. Skaar Lev Becker Alyssa H. Hasty 《International journal of molecular sciences》2022,23(13)
Adipocyte iron overload is a maladaptation associated with obesity and insulin resistance. The objective of the current study was to determine whether and how adipose tissue macrophages (ATMs) regulate adipocyte iron concentrations and whether this is impacted by obesity. Using bone marrow-derived macrophages (BMDMs) polarized to M0, M1, M2, or metabolically activated (MMe) phenotypes, we showed that MMe BMDMs and ATMs from obese mice have reduced expression of several iron-related proteins. Furthermore, the bioenergetic response to iron in obese ATMs was hampered. ATMs from iron-injected lean mice increased their glycolytic and respiratory capacities, thus maintaining metabolic flexibility, while ATMs from obese mice did not. Using an isotope-based system, we found that iron exchange between BMDMs and adipocytes was regulated by macrophage phenotype. At the end of the co-culture, MMe macrophages transferred and received more iron from adipocytes than M0, M1, and M2 macrophages. This culminated in a decrease in total iron in MMe macrophages and an increase in total iron in adipocytes compared with M2 macrophages. Taken together, in the MMe condition, the redistribution of iron is biased toward macrophage iron deficiency and simultaneous adipocyte iron overload. These data suggest that obesity changes the communication of iron between adipocytes and macrophages and that rectifying this iron communication channel may be a novel therapeutic target to alleviate insulin resistance. 相似文献
76.
电能计量领域的多功能低功耗设计 总被引:1,自引:0,他引:1
电力用户是我国电工仪器仪表最大的用户群体,需求量占整个市场的90%。电能表是我国电工仪表行业中产量最大的产品。本文讨论了电能表的低功耗设计需求以及Maxim 提供的 MAXQ3180低功耗电表设计方案。 相似文献
77.
Network traffic classification is essential in supporting network measurement and management.Many existing traffic classification approaches provide application-level results regardless of the network quality of service(QoS) requirements. In practice,traffic flows from the same application may have irregular network behaviors that should be identified to various QoS classes for best network resource management. To address the issues, we propose to conduct traffic classification with two newly de... 相似文献
78.
79.
Yan-Ruide Li Yang Zhou Matthew Wilson Adam Kramer Ryan Hon Yichen Zhu Ying Fang Lili Yang 《International journal of molecular sciences》2022,23(14)
Invariant natural killer T (iNKT) cells have the capacity to mount potent anti-tumor reactivity and have therefore become a focus in the development of cell-based immunotherapy. iNKT cells attack tumor cells using multiple mechanisms with a high efficacy; however, their clinical application has been limited because of their low numbers in cancer patients and difficulties in infiltrating solid tumors. In this study, we aimed to overcome these critical limitations by using α-GalCer, a synthetic glycolipid ligand specifically activating iNKT cells, to recruit iNKT to solid tumors. By adoptively transferring human iNKT cells into tumor-bearing humanized NSG mice and administering a single dose of tumor-localized α-GalCer, we demonstrated the rapid recruitment of human iNKT cells into solid tumors in as little as one day and a significantly enhanced tumor killing ability. Using firefly luciferase-labeled iNKT cells, we monitored the tissue biodistribution and pharmacokinetics/pharmacodynamics (PK/PD) of human iNKT cells in tumor-bearing NSG mice. Collectively, these preclinical studies demonstrate the promise of an αGC-driven iNKT cell-based immunotherapy to target solid tumors with higher efficacy and precision. 相似文献
80.
As the most recent melanocortin receptor (MCR) identified, melanocortin-5 receptor (MC5R) has unique tissue expression patterns, pharmacological properties, and physiological functions. Different from the other four MCR subtypes, MC5R is widely distributed in both the central nervous system and peripheral tissues and is associated with multiple functions. MC5R in sebaceous and preputial glands regulates lipid production and sexual behavior, respectively. MC5R expressed in immune cells is involved in immunomodulation. Among the five MCRs, MC5R is the predominant subtype expressed in skeletal muscle and white adipose tissue, tissues critical for energy metabolism. Activated MC5R triggers lipid mobilization in adipocytes and glucose uptake in skeletal muscle. Therefore, MC5R is a potential target for treating patients with obesity and diabetes mellitus. Melanocortin-2 receptor accessory proteins can modulate the cell surface expression, dimerization, and pharmacology of MC5R. This minireview summarizes the molecular and pharmacological properties of MC5R and highlights the progress made on MC5R in energy metabolism. We poInt. out knowledge gaps that need to be explored in the future. 相似文献