全文获取类型
收费全文 | 686300篇 |
免费 | 8534篇 |
国内免费 | 2051篇 |
专业分类
电工技术 | 12043篇 |
综合类 | 2798篇 |
化学工业 | 106318篇 |
金属工艺 | 29412篇 |
机械仪表 | 22620篇 |
建筑科学 | 15680篇 |
矿业工程 | 5084篇 |
能源动力 | 16676篇 |
轻工业 | 53198篇 |
水利工程 | 8579篇 |
石油天然气 | 16218篇 |
武器工业 | 77篇 |
无线电 | 73172篇 |
一般工业技术 | 139723篇 |
冶金工业 | 105826篇 |
原子能技术 | 16252篇 |
自动化技术 | 73209篇 |
出版年
2021年 | 5885篇 |
2020年 | 4310篇 |
2019年 | 5583篇 |
2018年 | 23360篇 |
2017年 | 22523篇 |
2016年 | 19883篇 |
2015年 | 7048篇 |
2014年 | 11145篇 |
2013年 | 28221篇 |
2012年 | 19761篇 |
2011年 | 31215篇 |
2010年 | 25805篇 |
2009年 | 25371篇 |
2008年 | 26738篇 |
2007年 | 27300篇 |
2006年 | 17601篇 |
2005年 | 16862篇 |
2004年 | 16114篇 |
2003年 | 15806篇 |
2002年 | 14765篇 |
2001年 | 13962篇 |
2000年 | 13468篇 |
1999年 | 13047篇 |
1998年 | 30237篇 |
1997年 | 21853篇 |
1996年 | 16983篇 |
1995年 | 13057篇 |
1994年 | 11792篇 |
1993年 | 11536篇 |
1992年 | 8975篇 |
1991年 | 8792篇 |
1990年 | 8659篇 |
1989年 | 8401篇 |
1988年 | 8065篇 |
1987年 | 7306篇 |
1986年 | 7076篇 |
1985年 | 7956篇 |
1984年 | 7192篇 |
1983年 | 6892篇 |
1982年 | 6223篇 |
1981年 | 6320篇 |
1980年 | 6055篇 |
1979年 | 6127篇 |
1978年 | 6027篇 |
1977年 | 6672篇 |
1976年 | 8319篇 |
1975年 | 5466篇 |
1974年 | 5259篇 |
1973年 | 5292篇 |
1972年 | 4585篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
This paper presents an analytical solution to the non-uniform pressure on thick-walled cylinder. The formulation is based on the linear elasticity theory (plain strain) and stress function method. As an example, the proposed solution is used to model the stress distribution due to non-uniform steel reinforcement corrosion in concrete. The model is formulated considering different scenarios of corrosion pressure distribution. It is validated against the finite element model for different cases of non-uniform pressure distributions. The results show that the corrosion-induced cracks are likely to start just beyond the anodic zone. This is confirmed by the experimental tests on concrete cylinder exposed to non-uniform accelerated corrosion of steel reinforcement. The model can be effectively used to calculate the distribution of corrosion-induced stresses in concrete. 相似文献
162.
163.
E. M. Godzhaev R. A. Bairamov R. A. Abbasov 《Surface Engineering and Applied Electrochemistry》2015,51(6):552-556
The paper describes the results of a study on the temperature and frequency dependences of the dielectric permeability and dielectric loss tangent of composite materials composed of low density polyethylene filled with cadmium sulfide (LDPE/CdS) and indium(III) selenide (LDPE/In2Se3) in the temperature range of 300–450 K and a frequency range of 0–1014 Hz. It is revealed that a variation in the filler content and the effect of external factors can yield novel composite materials with desired dielectric characteristics. 相似文献
164.
165.
Niluka M. Dissanayake Kelley M. Current Sherine O. Obare 《International journal of molecular sciences》2015,16(10):23482-23516
In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism’s ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells. 相似文献
166.
167.
168.
169.
Emna Ouni Sbastien Pyr dit Ruys Marie-Madeleine Dolmans Gaëtan Herinckx Didier Vertommen Christiani A. Amorim 《International journal of molecular sciences》2020,21(23)
Currently, the extracellular matrix (ECM) is considered a pivotal complex meshwork of macromolecules playing a plethora of biomolecular functions in health and disease beyond its commonly known mechanical role. Only by unraveling its composition can we leverage related tissue engineering and pharmacological efforts. Nevertheless, its unbiased proteomic identification still encounters some limitations mainly due to partial ECM enrichment by precipitation, sequential fractionation using unfriendly-mass spectrometry (MS) detergents, and resuspension with harsh reagents that need to be entirely removed prior to analysis. These methods can be technically challenging and labor-intensive, which affects the reproducibility of ECM identification and induces protein loss. Here, we present a simple new method applicable to tissue fragments of 10 mg and more. The technique has been validated on human ovarian tissue and involves a standardized procedure for sample processing with an MS-compatible detergent and combined centrifugation. This two-step protocol eliminates the need for laborious sample clarification and divides our samples into 2 fractions, soluble and insoluble, successively enriched with matrisome-associated (ECM-interacting) and core matrisome (structural ECM) proteins. 相似文献
170.
Hammons Joshua A. Tumey Scott J. Idell Yaakov Jeffries Jason R. 《JOM Journal of the Minerals, Metals and Materials Society》2020,72(1):176-186
JOM - Alpha-radiation damage in metals is a concern for long-term radioactive storage and systems that produce nuclear energy. Accurate prediction of irradiated material properties and failure... 相似文献