首页 | 官方网站   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   491篇
  免费   31篇
工业技术   522篇
  2023年   2篇
  2022年   1篇
  2021年   12篇
  2020年   5篇
  2019年   9篇
  2018年   11篇
  2017年   11篇
  2016年   20篇
  2015年   6篇
  2014年   18篇
  2013年   19篇
  2012年   17篇
  2011年   28篇
  2010年   19篇
  2009年   22篇
  2008年   21篇
  2007年   19篇
  2006年   21篇
  2005年   25篇
  2004年   19篇
  2003年   11篇
  2002年   8篇
  2001年   6篇
  2000年   11篇
  1999年   15篇
  1998年   41篇
  1997年   35篇
  1996年   19篇
  1995年   13篇
  1994年   12篇
  1993年   4篇
  1992年   3篇
  1991年   6篇
  1990年   5篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   2篇
  1984年   3篇
  1983年   1篇
  1982年   2篇
  1978年   2篇
  1977年   4篇
  1976年   3篇
  1975年   1篇
  1972年   1篇
  1938年   1篇
排序方式: 共有522条查询结果,搜索用时 109 毫秒
51.
The evolution of the Maillard reaction (MR) by measuring the available lysine and furosine (FUR) contents in adapted and follow‐up powdered milk‐based infant formulas over the shelf‐life storage period, at 20 and 37 °C, was studied. Available lysine and FUR contents were determined by fluorimetry and high‐performance liquid chromatography respectively. Statistically significant differences were found between adapted and follow‐up infant formulas with respect to the available lysine and FUR contents. Available lysine contents decreased significantly throughout the storage time, and the contents at 37 °C were lower than at 20 °C. A statistically significant increase in FUR contents was observed during the storage period, with the contents being high at 37 °C than at 20 °C. A simple regression analysis between the available lysine and FUR contents during (a) the first year (b) the second year and (c) the two storage years was applied. The best correlations were obtained during the first year of storage. The results obtained show a clear MR evolution during the storage of infant formulas. Copyright © 2003 Society of Chemical Industry  相似文献   
52.
In this work, an organic and nutrient removal pilot plant was used to study the temperature influence on phosphorus accumulating organisms. Three experiments were carried out at 13, 20 and 24.5 degrees C, achieving a high phosphorus removal percentage in all cases. The ASM2d model was calibrated at 13 and 20 degrees C and the Arrhenius equation constant was obtained for phosphorus removal processes showing that the temperature influences on the biological phosphorus removal subprocesses in a different degree. The 24.5 degrees C experiment was simulated using the model parameters obtained by means of the Arrhenius equation. The simulation results for the three experiments showed good correspondence with the experimental data, demonstrating that the model and the calibrated parameters were able to predict the pilot plant behaviour.  相似文献   
53.
Neuropathological examination was carried out on a patient aged 37 years who had suffered from Wolfram syndrome. Atrophy of the olfactory bulbs and tracts, atrophy of the optic nerves and chiasm, loss of neurons in the lateral geniculate nuclei mainly affecting the small cell layers, atrophy of the superior colliculus, loss of fibers in the cochlear nerve and mild loss of neurons in the cochlear nuclei and inferior colliculus, mild olivopontocerebellar atrophy, and demyelination of the pyramidal tracts were the main neuropathological findings. These correlated with anosmia, loss of vision, loss of hearing, cerebellar symptoms and signs, Babinski sign, and clonus, respectively, clinically observed in this patient. Mild neuron loss and gliosis in the preoptic and paraventricular area of the hypothalamus and mild motor neuron loss in the spinal cord did not reach thresholds of impaired function, although loss of neurons in discrete bulbar nuclei might have accounted for the late episode of food aspiration and suffocation. The relationship between memory loss, personality disturbances, and signs of prefrontal release and mild loss of neurons in the anterior and dorso-medial nuclei of the thalamus remains unclear.  相似文献   
54.
This paper presents the fracture behaviour of a thermoplastic elastomer, HYTREL 5556. Since with this material it is not possible to successfully apply the LEFM nor the EPFM, it has been studied by following the ESIS protocol for determining the essential work of fracture in plane stress and extended for mixed-mode conditions, which should give a material constant, independent of the sample geometry. DDENT specimens were used in two different thickness, and results showed that the essential works of fracture in plane stress and mixed-mode were the same for both thickness for this material. Received: 24 March 1997/Revised: 30 May 1997/Accepted: 30 May 1997  相似文献   
55.
The Cullera Estany is a coastal lagoon located in a highly intensified agriculture and tourist area in Valencia. This coastal lagoon has connections with the sea that produce marine intrusion and generate a freshwater interface. Four sampling campaigns were carried out during 2010 in order to analyse the phytoplankton composition and its relation to nutrient content through a Redundancy Analysis. Temperature, dissolved oxygen, nitrite and salinity are the main factors controlling the dynamics of phytoplankton community. During July and October, there is water column stratification; meanwhile in March, there is a well‐mixed water column. In addition, in May and July campaigns, hypoxia/anoxia conditions are detected at the bottom. The most abundant phytoplankton groups are Diatoms and Cryptophyceae. Diatoms and Cyanophyceae respond positively to temperature while Cryptophyceae, Prasinophyceae and Dinophyceae respond to high salinity and dissolved oxygen values. Furthermore, picoplankton is correlated inversely with nutrient concentrations.  相似文献   
56.
Nowadays, image analysis is becoming more important because of its ability to perform fast and non-invasive low-cost analysis on products and processes. Image analysis is a wide denomination that encloses classical studies on gray scale or RGB images, analysis of images collected using few spectral channels (sometimes called multispectral images) or, most recently, data treatments to deal with hyperspectral images, where the spectral direction is exploited in its full extension. Pioneering data treatments in image analysis were applied to simple images mainly for defect detection, segmentation and classification by the Computer Science community. From the late 80s, the chemometric community joined this field introducing powerful tools for image analysis, which were already in use for the study of classical spectroscopic data sets and were appropriately modified to fit the particular characteristics of image structures. These chemometric approaches adapt to images of all kinds, from the simplest to the hyperspectral images, and have provided new insights on the spatial and spectroscopic information of this kind of data sets. New fields open by the introduction of chemometrics on image analysis are exploratory image analysis, multivariate statistical process control (monitoring), multivariate image regression or image resolution. This paper reviews the different techniques developed in image analysis and shows the evolution in the information provided by the different methodologies, which has been heavily pushed by the increasing complexity of the image measurements in the spatial and, particularly, in the spectral direction.  相似文献   
57.
Barat R  Montoya T  Seco A  Ferrer J 《Water research》2011,45(12):3744-3752
The biologically induced precipitation processes can be important in wastewater treatment, in particular treating raw wastewater with high calcium concentration combined with Enhanced Biological Phosphorus Removal. Currently, there is little information and experience in modelling jointly biological and chemical processes. This paper presents a calcium phosphate precipitation model and its inclusion in the Activated Sludge Model No 2d (ASM2d). The proposed precipitation model considers that aqueous phase reactions quickly achieve the chemical equilibrium and that aqueous-solid change is kinetically governed. The model was calibrated using data from four experiments in a Sequencing Batch Reactor (SBR) operated for EBPR and finally validated with two experiments. The precipitation model proposed was able to reproduce the dynamics of amorphous calcium phosphate (ACP) formation and later crystallization to hydroxyapatite (HAP) under different scenarios. The model successfully characterised the EBPR performance of the SBR, including the biological, physical and chemical processes.  相似文献   
58.
A retrospective analysis of 42 patients treated by intramedullary nailing with the Gamma nail with a mean followup of 22.4 months is reported. The indications for the use of this nail were subtrochanteric fractures in 31 cases, diaphyseal femoral fractures in 10 cases, and segmental fracture in one case. Seven cases of the diaphyseal fractures were renailings for a previously placed nail. There was one pathologic fracture in the subtrochanteric group and three in the diaphyseal group. The indications of this new technique and its complications are analyzed.  相似文献   
59.
60.
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-23

京公网安备 11010802026262号