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   1058篇
  免费   61篇
电工技术   9篇
化学工业   347篇
金属工艺   8篇
机械仪表   9篇
建筑科学   39篇
矿业工程   1篇
能源动力   20篇
轻工业   207篇
水利工程   4篇
石油天然气   2篇
无线电   68篇
一般工业技术   172篇
冶金工业   80篇
原子能技术   6篇
自动化技术   147篇
  2024年   1篇
  2023年   14篇
  2022年   32篇
  2021年   57篇
  2020年   16篇
  2019年   24篇
  2018年   32篇
  2017年   23篇
  2016年   31篇
  2015年   18篇
  2014年   45篇
  2013年   65篇
  2012年   64篇
  2011年   88篇
  2010年   70篇
  2009年   70篇
  2008年   60篇
  2007年   73篇
  2006年   47篇
  2005年   46篇
  2004年   32篇
  2003年   36篇
  2002年   33篇
  2001年   14篇
  2000年   17篇
  1999年   16篇
  1998年   15篇
  1997年   13篇
  1996年   9篇
  1995年   14篇
  1994年   10篇
  1993年   5篇
  1992年   9篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
  1984年   4篇
  1983年   1篇
  1982年   1篇
  1974年   2篇
  1969年   1篇
  1968年   1篇
排序方式: 共有1119条查询结果,搜索用时 839 毫秒
81.
This paper addresses the control design problem for a certain class of continuous-time nonlinear systems subject to actuator saturations. The system under consideration consists of a system with two nested nonlinearities of different type: saturation nonlinearity and cone-bounded nonlinearity. The control law investigated for stabilization purposes depends on both the state and the cone-bounded nonlinearity. Constructive conditions based on LMIs are then provided to ensure the regional or global stability of the system. Different points, like other approaches issued from the literature, are quickly discussed. An illustrative example allows to show the interest of the approach proposed.  相似文献   
82.
Transfection and transduction studies involving the use of thefull-length dystrophin (11 kb) or the truncated mini-gene (6kb) cDNAs are hampered by the large size of the resulting viralor non-viral expression vectors. This usually results in verylow yields of transgene-expressing cells. Moreover, the detectionof the few transgene-expressing cells is often tedious and costly.For these reasons, expression vectors containing the enhancedgreen fluorescent protein (EGFP) fused with the N-termini ofmini- and full-length human dystrophin were constructed. Theseconstructs were tested by transfection of Phoenix cells withEffectene, resulting after 48 h in a green fluorescent signalin 20% of cells. Analysis of the cell extracts by immunoblottingwith the use of a monoclonal antibody specific to the dystrophinC-terminus confirmed the expression of EGFP–mini- (240kDa) and EGFP–full-length human dystrophin (450 kDa) fusionproteins. Moreover, following the in vivo electroporation ofthe plasmids containing the EGFP–mini- and full-lengthdystrophin in mouse muscles, both fluorescent proteins wereobserved in cryostat sections in their normal location underthe plasma membrane. This indicates that the fusion of EGFPto dystrophin or mini-dystrophin did not interfere with thenormal localization of the protein. In conclusion, the fusionof EGFP provides a good tool for the search of the best methodsto introduce mini- or full-length dystrophin cDNA in the cells(in vitro) or muscle fibers (in vivo) for the establishmentof a treatment by gene therapy of Duchenne muscular dystrophypatients.  相似文献   
83.
Effects of Botrytis cinerea infection on Champagne wine foaming properties   总被引:1,自引:0,他引:1  
Qualitative effects of Botrytis cinerea infection were studied by comparing the foaming properties of Champagnes obtained from healthy grapes with those from grapes infected by B cinerea. This is of particular interest when it is considered that the foaming properties of Champagne wines are important in terms of product attractiveness for the consumer. Experiments using artificial viewing equipment clearly showed the dramatic effects on Champagne foam characteristics when grape berries were highly infected. The speed at which liquid separated from the foam (expressed as liquid height LS) in the glass depended largely on the level of infection for Chardonnary and Pinot noir wines (+268% for Chardonnary wines at 40% infection and +627% for Pinot noir wines at 20% infection). B cinerea infection reduced the time (LT) at which liquid first appeared in the glass; for Pinot noir wines an infection level of 20% caused very rapid drainage. The time of pouring (PT, ie the time to fill the glass under controlled conditions) also diminished considerably at an infection level of 20% for both Pinot noir and Pinot meunier wines (?74 and ?58% respectively). Mouldiness considerably altered the foam height observed 80 s (H80) after the start of pouring (?83% for Pinot noir and ?89% for Pinot meunier at 20% infection). Champagne foamability was also quantified using a sparging technique to standardise effervescence. Foamability suffered considerably (?60 to ?65%) when the B cinerea infection level was 20% as compared to control Champagnes. All wines studied had low and very similar protein contents. Differences in the concentrations of these compounds, which are generally implicated in the formation of foam in sparkling wines, could not explain the differences in Champagne foaming properties observed here. © 2001 Society of Chemical Industry  相似文献   
84.
This study evaluated the effect of aluminum phosphate (AlPO4) additions on the crystallization behavior and bioactivity of potassium fluorrichterite glasses and glass–ceramics. Four glass compositions with increasing amounts of AlPO4 were melted. Mica and fluorrichterite were present in all glass–ceramics after crystallization. The microstructure consisted of platelet-shaped mica and prismatic fluorrichterite crystals. After incubation in simulated body fluid, a layer consisting of spherical-nanosized particles was present on the surface of the glasses. X-ray diffraction revealed the presence of hydroxyapatite after incubation of the glass and glass–ceramic powders. The addition of AlPO4 promoted mica nucleation and bioactivity in K-fluorrichterite glass–ceramics.  相似文献   
85.
86.
Standard neuropsychological tests administered in a constrained and artificial laboratory environment are often insensitive to the real-life deficits faced by patients with traumatic brain injury (TBI). The Revised Strategy Application Test (R-SAT) creates an unstructured environment in the laboratory in which environmental cues and internal habits oppose the most efficient strategy, thus mimicking the real-life situations that are problematic for patients with TBI. In this study, R-SAT performance was related both to severity of TBI (i.e., depth of coma) sustained 2–3 years earlier and to quality of life outcome as assessed by the Sickness Impact Profile. This relationship held after accounting for variance attributable to TBI-related slowing and inattention. These findings support the validity of the R-SAT and suggest that behavioral correlates of quality of life outcome in TBI can be assessed in the laboratory with unstructured tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
87.
88.
The enthalpy of dissolution of two food powders, maltodextrin and skim milk, was studied by means of isothermal solution calorimetry. The effects of the moisture content and the physical state of the samples were investigated. A reduced exothermic response was found as the moisture content of the samples increased. It was shown that this effect is reversible upon re-drying of the solid, unless crystallization occurs. In the skim milk powder, crystallization of lactose occurred, leading to a less exothermic response. In addition, the dissolution kinetics of single particles was followed in situ with real time video acquisition and a novel image analysis technique. The data showed a significant effect of the physical state of the powder on the dissolution kinetics. Fully amorphous skim milk powder dissolved significantly faster than the recrystallized counterpart. A clear relation was observed between the physical state of the powders, their thermodynamic response and the dissolution kinetics.  相似文献   
89.
The authors have translated the Nisonger Child Behavior Rating Form (Nisonger CBRF) into French. The resulting Grillee d'évaluation comportementale pour enfants Nisonger (GéCEN) was completed by 383 parents and 328 teachers. The congruence coefficients between the factor structure obtained from the Québec data and that obtained from the American data are also presented. Except for the congruence coefficient for the irritability scale from the GéCEN-teacher, the congruence coefficients for the parent and teacher profiles exhibit a good level of factor stability between the Nisonger CBRF, and the GéCEN. The internal consistency indicators are good to excellent for the GéCEN-parent and the GéCEN-teacher. The clinical applications of this dual diagnosis assessment tool (mental retardation and psychopathology) among children and teenagers are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
90.
A failure investigation was performed on a ball joint from an ATV front suspension system. The location of the fracture was the bearing ball/stud interface, which is a fusion-welded joint, and occurred after approximately 20 h of field-testing. The two parts are made out of carbon steel and were previously heat-treated. Many elongated MnS inclusions were found in the stud material, and these inclusions were parallel to the symmetry axis. Even though these inclusions were not significantly sized, their number was important. Macroscopic evidence showed that the joint failed in a ductile mode under centered tensile overload. Microscopic examination showed that MnS orientation changed in the fusion joint area. The inclusions had been redirected during the welding process and laid parallel to the fracture surface. This reorientation caused a significant decrease in the effective cross section of the joint and overload fracture occurred.  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