首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   672757篇
  免费   8057篇
  国内免费   1408篇
电工技术   11737篇
综合类   2778篇
化学工业   103203篇
金属工艺   31030篇
机械仪表   23613篇
建筑科学   15261篇
矿业工程   5161篇
能源动力   15844篇
轻工业   49462篇
水利工程   8424篇
石油天然气   15727篇
武器工业   40篇
无线电   71380篇
一般工业技术   138742篇
冶金工业   100974篇
原子能技术   15194篇
自动化技术   73652篇
  2021年   5519篇
  2019年   5305篇
  2018年   25107篇
  2017年   24435篇
  2016年   20478篇
  2015年   6750篇
  2014年   10529篇
  2013年   26496篇
  2012年   19509篇
  2011年   32721篇
  2010年   27451篇
  2009年   26644篇
  2008年   27957篇
  2007年   29450篇
  2006年   16562篇
  2005年   17599篇
  2004年   16064篇
  2003年   15710篇
  2002年   14164篇
  2001年   13034篇
  2000年   12622篇
  1999年   12142篇
  1998年   27801篇
  1997年   20139篇
  1996年   15743篇
  1995年   12088篇
  1994年   10953篇
  1993年   10696篇
  1992年   8405篇
  1991年   8178篇
  1990年   8049篇
  1989年   7811篇
  1988年   7530篇
  1987年   6798篇
  1986年   6578篇
  1985年   7443篇
  1984年   6760篇
  1983年   6476篇
  1982年   5837篇
  1981年   5951篇
  1980年   5669篇
  1979年   5769篇
  1978年   5694篇
  1977年   6208篇
  1976年   7708篇
  1975年   5129篇
  1974年   4923篇
  1973年   5005篇
  1972年   4289篇
  1971年   4044篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Microbial fuel cell (MFC) is a promising technology for simultaneous wastewater treatment and energy harvesting. The properties of the anode material play a critical role in the performance of the MFC. In this study, graphene oxide was prepared by a modified hummer's method. A thin layer of graphene oxide was incorporated on the carbon brush using an electrophoretic technique. The deoxygenated graphene oxide formed on the surface of the carbon brush (RGO-CB) was investigated as a bio-anode in MFC operated with real wastewater. The performance of the MFC using the RGO-CB was compared with that using plain carbon brush anode (PCB). Results showed that electrophoretic deposition of graphene oxide on the surface of carbon brush significantly enhanced the performance of the MFC, where the power density increased more than 10 times (from 33 mWm?2 to 381 mWm?2). Although the COD removal was nearly similar for the two MFCs, i.e., with PCB and RGO-CB; the columbic efficiency significantly increased in the case of RGO-CB anode. The improved performance in the case of the modified electrode was related to the role of the graphene in improving the electron transfer from the microorganism to the anode surface, as confirmed from the electrochemical impedance spectroscopy measurements.  相似文献   
152.
Russian Journal of Non-Ferrous Metals - This article is devoted to the influence of sodium lignosulfonate (SL), anionic surfactants (sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate...  相似文献   
153.
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   
154.
155.
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   
156.
157.
158.
159.
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   
160.
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   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号