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   99519篇
  免费   8023篇
  国内免费   4275篇
电工技术   5618篇
技术理论   6篇
综合类   6253篇
化学工业   16554篇
金属工艺   6160篇
机械仪表   6954篇
建筑科学   8074篇
矿业工程   3405篇
能源动力   2905篇
轻工业   6288篇
水利工程   1658篇
石油天然气   7332篇
武器工业   806篇
无线电   10704篇
一般工业技术   11562篇
冶金工业   4893篇
原子能技术   1011篇
自动化技术   11634篇
  2024年   449篇
  2023年   1773篇
  2022年   3116篇
  2021年   4265篇
  2020年   3312篇
  2019年   2699篇
  2018年   2907篇
  2017年   3285篇
  2016年   3042篇
  2015年   4107篇
  2014年   4903篇
  2013年   5845篇
  2012年   6313篇
  2011年   6732篇
  2010年   5774篇
  2009年   5518篇
  2008年   5370篇
  2007年   5085篇
  2006年   5414篇
  2005年   4713篇
  2004年   2990篇
  2003年   2834篇
  2002年   2657篇
  2001年   2414篇
  2000年   2327篇
  1999年   2638篇
  1998年   2085篇
  1997年   1730篇
  1996年   1701篇
  1995年   1411篇
  1994年   1155篇
  1993年   737篇
  1992年   646篇
  1991年   438篇
  1990年   350篇
  1989年   301篇
  1988年   227篇
  1987年   150篇
  1986年   122篇
  1985年   70篇
  1984年   53篇
  1983年   44篇
  1982年   41篇
  1981年   28篇
  1980年   25篇
  1979年   16篇
  1978年   1篇
  1965年   1篇
  1959年   2篇
  1951年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Xu X  Zhao Z  Qin L  Wei W  Levine JE  Mirkin CA 《Analytical chemistry》2008,80(14):5616-5621
We report a novel and straightforward fluorescence recovery assay which enables the detection of protein-DNA interactions and simultaneously determines relative binding affinities of sequence-specific DNA-binding proteins for a variety of DNA sequences in a multiplexed format. The detection of protein-DNA binding is accomplished by monitoring fluorescence recovery during exonuclease digestion of DNA sequences that are modified with fluorophore-quencher pairs. Retardation of fluorescence recovery occurs with binding of the protein to the putative DNA binding element, which arrests exonuclease digestion. The assay detects protein-DNA binding in a homogeneous solution simply, quickly, and reliably without using radioisotopes. Multiplexing is possible by labeling different DNA sequences with spectrally distinct dyes, allowing simultaneous analysis of experimental and control binding reactions in the same mixture.  相似文献   
992.
Abstract

Scientists increasingly witness the applications of MoS2 and MoO2 in the field of energy conversion and energy storage. On the one hand, MoS2 and MoO2 have been widely utilized as promising catalysts for electrocatalytic or photocatalytic hydrogen evolution in aqueous solution. On the other hand, MoS2 and MoO2 have also been verified as efficient electrode material for lithium ion batteries. In this review, the synthesis, structure and properties of MoS2 and MoO2 are briefly summarized according to their applications for H2 generation and lithium ion batteries. Firstly, we overview the recent advancements in the morphology control of MoS2 and MoO2 and their applications as electrocatalysts for hydrogen evolution reactions. Secondly, we focus on the photo-induced water splitting for H2 generation, in which MoS2 acts as an important co-catalyst when combined with other semiconductor catalysts. The newly reported research results of the significant functions of MoS2 nanocomposites in photo-induced water splitting are presented. Thirdly, we introduce the advantages of MoS2 and MoO2 for their enhanced cyclic performance and high capacity as electrode materials of lithium ion batteries. Recent key achievements in MoS2- and MoO2-based lithium ion batteries are highlighted. Finally, we discuss the future scope and the important challenges emerging from these fascinating materials.  相似文献   
993.
994.
淮北煤系高岭土蕴藏量丰富,开发超细煅烧高岭土是其发展的主要方向之一,本文从现有生产工艺出发探讨工艺革新改造之法。  相似文献   
995.
The starch composite films (SCFs) will be one of the best alternative packaging materials to petroleum based plastic films, which mitigates white pollution and energy consumption. However, weak mechanical stability, water resistance, and dyeability has hindered the application of SCFs. Herein, a bioinspired robust SCFs with super-hydrophobicity and excellent structural colors were prepared by fiber-reinforcement and assembling SiO2/Polydimethylsiloxane (PDMS) amorphous arrays on the surface of SCFs. The properties of the designed SCFs were investigated by various methods including scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), a tensile test, contact angle (CA) test, and an optical test. The results showed that the obtained SCFs possessed a higher tensile strength (55.17 MPa) attributed to the formed abundant hydrogen bonds between the molecular chains of the starch, cellulose fiber, and polyvinyl alcohol. Benefiting from the nanostructure with rough surface which were modified by materials with low surface free energy, the contact angle and sliding angle of the film reached up to 154° and 2°, respectively. The colors which were produced by the constructive interference of the coherent scattered light could cover all of the visible regions by tuning the diameters of the SiO2 nanoparticles. The strategy in the present study not only reinforces the mechanical strength and water resistance of SCFs but also provides an environmentally friendly way to color the them, which shows unprecedented application potential in packaging materials of the starch composite films.  相似文献   
996.
In this study,the nitrogen removal performance of partial denitrificaiton/anammox(PDA) process was investigated by using an UASB reactor.High total nitrogen(TN) removal efficiency(91.97%) was achieved at an influent nitrogen loading rate of 0.64 kg/(m3·d).Anammox bacteria did execute the function of converting nitrate to nitrite in PDA system according to 15N isotope labeling experiments and the contribution was approximately 36.3%.Candidatus_Brocadia,Candidatus_Kuenenia an...  相似文献   
997.
998.
Rice blast is one of the main diseases in rice and can occur in different rice growth stages. Due to the complicated procedure of panicle blast identification and instability of panicle blast infection influenced by the environment, most cloned rice resistance genes are associated with leaf blast. In this study, a rice panicle blast resistance gene, Pb2, was identified by genome-wide association mapping based on the panicle blast resistance phenotypes of 230 Rice Diversity Panel 1 (RDP1) accessions with 700,000 single-nucleotide polymorphism (SNP) markers. A genome-wide association study identified 18 panicle blast resistance loci (PBRL) within two years, including 9 reported loci and 2 repeated loci (PBRL2 and PBRL13, PBRL10 and PBRL18). Among them, the repeated locus (PBRL10 and PBRL18) was located in chromosome 11. By haplotype and expression analysis, one of the Nucleotide-binding domain and Leucine-rich Repeat (NLR) Pb2 genes was highly conserved in multiple resistant rice cultivars, and its expression was significantly upregulated after rice blast infection. Pb2 encodes a typical NBS-LRR protein with NB-ARC domain and LRR domain. Compared with wild type plants, the transgenic rice of Pb2 showed enhanced resistance to panicle and leaf blast with reduced lesion number. Subcellular localization of Pb2 showed that it is located on plasma membrane, and GUS tissue-staining observation found that Pb2 is highly expressed in grains, leaf tips and stem nodes. The Pb2 transgenic plants showed no difference in agronomic traits with wild type plants. It indicated that Pb2 could be useful for breeding of rice blast resistance.  相似文献   
999.
钙钛矿太阳能电池研究进展及面临的挑战   总被引:1,自引:0,他引:1  
  相似文献   
1000.
In recent years,a new generation of storage ring-based light sources,known as diffraction-limited storage rings(DLSRs),whose emittance approaches the diffractio...  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