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   3634篇
  免费   192篇
  国内免费   23篇
电工技术   25篇
综合类   61篇
化学工业   561篇
金属工艺   89篇
机械仪表   70篇
建筑科学   133篇
矿业工程   31篇
能源动力   61篇
轻工业   490篇
水利工程   29篇
石油天然气   51篇
武器工业   1篇
无线电   131篇
一般工业技术   453篇
冶金工业   1302篇
原子能技术   28篇
自动化技术   333篇
  2024年   11篇
  2023年   24篇
  2022年   71篇
  2021年   123篇
  2020年   71篇
  2019年   66篇
  2018年   111篇
  2017年   113篇
  2016年   116篇
  2015年   91篇
  2014年   99篇
  2013年   219篇
  2012年   148篇
  2011年   173篇
  2010年   156篇
  2009年   111篇
  2008年   126篇
  2007年   92篇
  2006年   78篇
  2005年   70篇
  2004年   60篇
  2003年   61篇
  2002年   52篇
  2001年   28篇
  2000年   54篇
  1999年   75篇
  1998年   415篇
  1997年   237篇
  1996年   158篇
  1995年   103篇
  1994年   103篇
  1993年   74篇
  1992年   24篇
  1991年   26篇
  1990年   12篇
  1989年   14篇
  1988年   12篇
  1987年   10篇
  1986年   14篇
  1985年   13篇
  1984年   12篇
  1983年   14篇
  1982年   10篇
  1981年   12篇
  1980年   19篇
  1979年   9篇
  1978年   12篇
  1977年   44篇
  1976年   66篇
  1972年   8篇
排序方式: 共有3849条查询结果,搜索用时 15 毫秒
1.
2.
3.
The potential of time‐domain nuclear magnetic resonance (TD‐NMR) for the real‐time monitoring of solution radical polymerizations is demonstrated. A model system composed of a redox‐pair initiator system, acrylamide as monomer and water as solvent was investigated. A second‐generation continuous wave free precession technique was employed to measure the longitudinal relaxation time constant (T1) of the samples throughout the polymerization reactions. This parameter was shown to be sensitive to the reactant feed free‐radical enhancement of the water molecule relaxation time, making it a good probe to monitor monomer conversion in real time in an automated, non‐destructive fashion. It was found that the T1 value was better than the transverse relaxation time constant (T2) for describing the evolution of the polymerization reactions, due to its greater sensitivity to paramagnetic effects. The TD‐NMR signal variation observed was linked to the formation, propagation and termination steps of the radical polymerization kinetics scheme. These first results may contribute to the application of real‐time monitoring of radical polymerization reactions employing low‐cost and robust TD‐NMR spectrometers. © 2018 Society of Chemical Industry  相似文献   
4.
5.
Identification of Lophius budegassa(black‐bellied angler) and L. piscatorius(angler) (Lophiiformes) was carried out on the amplification of a 486 bp tRNAGlu/cytochrome b segment using the polymerase chain reaction (PCR). Direct DNA sequencing of 6 PCR products was carried out. Six restriction endonucleases (AluI, CfoI, HaeIII, HinfI, Mae, and ScrFI) with different species‐specific restriction fragment length polymorphism (RFLP) were selected. Digestions of PCR products from 30 individuals showed no intraspecific polymorphism. Double digestions (CfoI and HinfI, and HaeIII and ScrFI) were simpler and more rapid than single digestions. This technique is suitable for distinguishing tails of both Lophius species.  相似文献   
6.
Valproate (VPA) has been shown to interact with all the major antiepileptic drugs (AEDs) through two mechanisms of action: displacement from albumin binding sites and inhibition of drug metabolism. More recently, evidence showed that VPA inhibits the elimination of drugs metabolized by glucuronide conjugation. Lorazepam (LZP), which is primarily eliminated by conjugation with glucuronic acid, is administered concurrently with VPA both in treatment of epilepsy and in patients treated with VPA for psychiatric disorders. Therefore, a significant drug interaction is likely. We investigated such interaction both in in vitro isolated perfused rat liver (IPRL) and in normal subjects. LZP [2 mg, intravenous (i.v.) bolus] was administered to 8 normal volunteers before and after chronic dosing with VPA. In 6 of 8 subjects, VPA significantly decreased LZP plasma clearance by an average of 40% (p < 0.05) and increased LZP concentrations by decreasing formation clearance of the LZP glucuronide. In the IPRL studies, VPA also significantly decreased formation of LZP glucuronide (from 0.72 +/- 0.14 to 0.22 +/- 0.15 ml/h/kg, p < 0.05), indicating that IPRL is a useful tool for evaluation of the effect of VPA on drugs eliminated by glucuronide conjugation.  相似文献   
7.
Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time.  相似文献   
8.
The GC/MS and NMR analysis of the reaction products of naphthalene with 1-bromohexane were reported. The products obtained were suggested to have six isomers of linear hexylnaphthalene and the structure of each isomer was determined by GC/MS and NMR spectra. For the first time, the unique chemical shift data were obtained. The content of each isomer calculated by 1H NMR and 13C NMR spectra was consistent with that by GC/MS spectra, which confirmed the accuracy of NMR data.  相似文献   
9.
10.
The study of the micromammalian parasite complexes in the Belorussian part of the evacuation zone of the Chernobyl nuclear station revealed 13 species of Coccidia and 30 species of ectoparasitic Arthropoda. Total increase of abundance and biodiversity of both parasites and their hosts was observed. The part of ectoparasites being epidemically hazardous was significantly increased. An analysis of a long-term dynamics of parasite abundance reveals their adaptation to new conditions in the Belorussia.  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