全文获取类型
收费全文 | 380197篇 |
免费 | 4949篇 |
国内免费 | 847篇 |
专业分类
电工技术 | 6319篇 |
综合类 | 2590篇 |
化学工业 | 59885篇 |
金属工艺 | 18514篇 |
机械仪表 | 15174篇 |
建筑科学 | 8769篇 |
矿业工程 | 2523篇 |
能源动力 | 6999篇 |
轻工业 | 31374篇 |
水利工程 | 4388篇 |
石油天然气 | 6514篇 |
武器工业 | 32篇 |
无线电 | 38647篇 |
一般工业技术 | 75038篇 |
冶金工业 | 52331篇 |
原子能技术 | 6981篇 |
自动化技术 | 49915篇 |
出版年
2022年 | 2177篇 |
2021年 | 3090篇 |
2019年 | 2420篇 |
2018年 | 22672篇 |
2017年 | 22231篇 |
2016年 | 16267篇 |
2015年 | 3560篇 |
2014年 | 4711篇 |
2013年 | 11209篇 |
2012年 | 11463篇 |
2011年 | 23514篇 |
2010年 | 20343篇 |
2009年 | 17935篇 |
2008年 | 18928篇 |
2007年 | 21472篇 |
2006年 | 7470篇 |
2005年 | 10334篇 |
2004年 | 8612篇 |
2003年 | 8180篇 |
2002年 | 6870篇 |
2001年 | 5832篇 |
2000年 | 5728篇 |
1999年 | 5483篇 |
1998年 | 12716篇 |
1997年 | 9015篇 |
1996年 | 6996篇 |
1995年 | 5412篇 |
1994年 | 4825篇 |
1993年 | 4709篇 |
1992年 | 3751篇 |
1991年 | 3475篇 |
1990年 | 3626篇 |
1989年 | 3501篇 |
1988年 | 3342篇 |
1987年 | 2924篇 |
1986年 | 2968篇 |
1985年 | 3404篇 |
1984年 | 3244篇 |
1983年 | 2914篇 |
1982年 | 2753篇 |
1981年 | 2836篇 |
1980年 | 2738篇 |
1979年 | 2643篇 |
1978年 | 2703篇 |
1977年 | 2960篇 |
1976年 | 3812篇 |
1975年 | 2379篇 |
1974年 | 2243篇 |
1973年 | 2379篇 |
1972年 | 1972篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Akopdzhanyan T. G. Chemagina E. A. Borovinskaya I. P. 《Russian Journal of Non-Ferrous Metals》2020,61(6):686-690
Russian Journal of Non-Ferrous Metals - The synthesis and sintering of the (AlN)x(SiC)1 – x solid solution have been studied under conditions of self-propagating high-temperature synthesis... 相似文献
72.
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
73.
74.
75.
76.
77.
78.
V. I. Zubkov O. V. Kucherova I. N. Yakovlev A. V. Solomonov 《Russian Microelectronics》2015,44(3):203-209
An automated system for integrated electrophysical and optical studies of semiconductor nanoheterostructures, which operates in a wide temperature range from 15 to 475 K, is designed. The setup is intended to measure the temperature and frequency admittance and electroluminescence spectra of light-emitting diode and laser chips formed on substrates of diameter up to 50.2 mm, and the distribution of parameters over the wafer. The setup includes the closed-cycle helium cryogenic station, LCR meter, and temperature controller. The characterization results of nanoheterostructures with InGaN/GaN multiple quantum wells, which are used for creating highly efficient white and blue light-emitting diodes, are presented. 相似文献
79.
I. N. Andronov Yu. I. Ryabkov N. P. Bogdanov N. A. Severova A. N. Danilov I. V. Churilina 《Russian Metallurgy (Metally)》2015,2015(10):778-784
The influence of the thermal cycling conditions on the thermal-cycling creep of a TN-1 alloy and the related irreversible deformations is studied. The conditions under which an anomalous increase in the irreversible deformations begins are determined. The structural mechanism of the irreversible deformations of an equiatomic alloy is shown to be analogous to the structural mechanism of metal creep at high temperatures: it predominantly has a dislocation character. It is proposed to use the effect of anomalous increase in the deformation of materials with reversible martensitic transformations for forming parts made of these materials at low temperatures. 相似文献
80.
Maria Luisa Calabr Nayana Lazzari Giulia Rigotto Marco Tonello Antonio Sommariva 《International journal of molecular sciences》2020,21(23)
The mechanisms by which neoplastic cells disseminate from the primary tumor to metastatic sites, so-called metastatic organotropism, remain poorly understood. Epithelial–mesenchymal transition (EMT) plays a role in cancer development and progression by converting static epithelial cells into the migratory and microenvironment-interacting mesenchymal cells, and by the modulation of chemoresistance and stemness of tumor cells. Several findings highlight that pathways involved in EMT and its reverse process (mesenchymal–epithelial transition, MET), now collectively called epithelial–mesenchymal plasticity (EMP), play a role in peritoneal metastases. So far, the relevance of factors linked to EMP in a unique peritoneal malignancy such as pseudomyxoma peritonei (PMP) has not been fully elucidated. In this review, we focus on the role of epithelial–mesenchymal dynamics in the metastatic process involving mucinous neoplastic dissemination in the peritoneum. In particular, we discuss the role of expression profiles and phenotypic transitions found in PMP in light of the recent concept of EMP. A better understanding of EMP-associated mechanisms driving peritoneal metastasis will help to provide a more targeted approach for PMP patients selected for locoregional interventions involving cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. 相似文献