全文获取类型
收费全文 | 313篇 |
免费 | 37篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 40篇 |
综合类 | 12篇 |
化学工业 | 19篇 |
金属工艺 | 69篇 |
机械仪表 | 18篇 |
建筑科学 | 22篇 |
矿业工程 | 4篇 |
能源动力 | 26篇 |
轻工业 | 10篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
武器工业 | 1篇 |
无线电 | 11篇 |
一般工业技术 | 52篇 |
冶金工业 | 22篇 |
原子能技术 | 6篇 |
自动化技术 | 39篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 13篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 19篇 |
2013年 | 29篇 |
2012年 | 32篇 |
2011年 | 38篇 |
2010年 | 29篇 |
2009年 | 30篇 |
2008年 | 20篇 |
2007年 | 22篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
排序方式: 共有357条查询结果,搜索用时 0 毫秒
1.
Renata Gruszka Krzysztof Zakrzewski Pawe Piotr Liberski Magdalena Zakrzewska 《International journal of molecular sciences》2021,22(2)
Numerous molecular factors disrupt the correctness of the cell cycle process leading to the development of cancer due to increased cell proliferation. Among known causative factors of such process is abnormal gene expression. Nowadays in the light of current knowledge such alterations are frequently considered in the context of mRNA–miRNA correlation. One of the molecular factors with potential value in tumorigenesis is the feedback loop between MYC and E2F genes in which miR-17-5p and miR-20a from the miR-17-92 cluster are involved. The current literature shows that overexpression of the members of the OncomiR-1 are involved in the development of many solid tumors. In the present work, we investigated the expression of components of the MYC/E2F/miR-17-92 network and their closely related elements including members of MYC and E2F families and miRNAs from two paralogs of miR-17-92: miR-106b-25 and miR-106a-363, in the most common brain tumors of childhood, pilocytic astrocytoma (PA), WHO grade 1; ependymoma (EP), WHO grade 2; and medulloblastoma (MB), WHO grade 4. We showed that the highest gene expression was observed in the MYC family for MYCN and in the E2F family for E2F2. Positive correlation was observed between the gene expression and tumor grade and type, with the highest expression being noted for medulloblastomas, followed by ependymomas, and the lowest for pilocytic astrocytomas. Most members of miR-17-92, miR-106a-363 and miR-106b-25 clusters were upregulated and the highest expression was noted for miR-18a and miR-18b. The rest of the miRNAs, including miR-19a, miR-92a, miR-106a, miR-93, or miR-25 also showed high values. miR-17-5p, miR-20a obtained a high level of expression in medulloblastomas and ependymomas, while close to the control in the pilocytic astrocytoma samples. miRNA expression also depended on tumor grade and histology. 相似文献
2.
3.
4.
In this paper, by using the concept of (A,η)-accretive mappings and the new resolvent operator technique associated with (A,η)-accretive mappings, we introduce and study a system of general mixed quasivariational inclusions involving (A,η)-accretive mappings in Banach spaces, and construct a new perturbed iterative algorithm with mixed errors for this system of nonlinear (A,η)-accretive variational inclusions in q-uniformly smooth Banach spaces. Our results improve and generalize the corresponding results of recent works. 相似文献
5.
6.
Psychotherapy studies published in the Journal of Counseling Psychology (JCP) and the Journal of Consulting and Clinical Psychology (JCCP) between 1978 and 1992 were examined. Differences were found between the 2 journals. JCP published mostly process, outcome, and analog research, whereas JCCP published mostly outcome research. Most process and process-outcome studies across journals were of individual, brief therapy. Across the years, more diversity was evident in samples used in process research in terms of student status, gender, and race of clients and therapists. Three content areas were prominent in the process measures and classic studies: therapist techniques, therapist influence, and facilitative conditions. Lists are provided of the frequently used measures, most productive authors, and classic studies in process research. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
在630℃下,对P92钢进行应力控制下的蠕变-疲劳交互作用实验,研究P92钢高温蠕变-疲劳交互作用下的裂纹扩展行为,并结合断口形貌分析蠕变-疲劳裂纹扩展的机理以及a-N曲线的转折点含义。结果表明:P92钢在蠕变-疲劳交互作用下的断裂属于蠕变韧性断裂,应该用(C_t)_(avg)作为裂纹扩展的断裂参量;P92钢在蠕变-疲劳交互条件下,试样的断口主要表现为蠕变孔洞以及微裂纹。此外,发现a-lg(N_i/N_f)曲线以及(da-dN)-N曲线中的拐点,分别对应蠕变-疲劳裂纹萌生区向扩展区转变周次以及扩展区向瞬断区转变的周次。 相似文献
8.
采用自孕育法制备新型的ZA92镁合金,研究了冷却槽对组织的细化作用,并对其机理进行了分析。结果表明:合金熔体内部的形核与冷却槽的激冷作用、熔体的流动速度及剪切力的大小有关,合适的冷却槽角度有利于晶粒的游离和增殖。熔体在流经冷却槽的过程中,其组织变化趋势为:粗大枝晶→细小枝晶→等轴晶→蔷薇状晶和近球状晶。冷却槽角度较大或较小均不利于组织的细化,当冷却槽角度在30~45°之间时,坯料组织的晶粒分布比较集中且细小,其平均晶粒尺寸在47.5~51.4μm之间。 相似文献
9.
基于断裂力学理论,针对不同面内拘束效应下P92钢高温蠕变裂纹扩展(Creep crack growth,CCG)进行了数据模拟与分析。研究发现不同的拘束效应对CCG行为有着各异的影响,主要分析了试样几何形状、尺寸以及初始裂纹深度等对CCG行为的影响,并且着重研究比较这3种耦合拘束效应对CCG行为的影响程度。基于多种耦合拘束对CCG行为的影响程度做了横向比较,研究发现:试样几何形状对CCG行为的影响程度要大于几何尺寸,试样尺寸和初始裂纹深度对CCG行为的影响程度相似,试样形状比初始裂纹深度的影响程度更大。 相似文献
10.