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   1759篇
  免费   159篇
  国内免费   25篇
电工技术   2篇
综合类   69篇
化学工业   428篇
金属工艺   8篇
机械仪表   5篇
建筑科学   22篇
矿业工程   42篇
能源动力   7篇
轻工业   1112篇
水利工程   11篇
石油天然气   147篇
无线电   4篇
一般工业技术   69篇
冶金工业   11篇
原子能技术   4篇
自动化技术   2篇
  2024年   20篇
  2023年   31篇
  2022年   51篇
  2021年   58篇
  2020年   79篇
  2019年   61篇
  2018年   51篇
  2017年   65篇
  2016年   42篇
  2015年   58篇
  2014年   61篇
  2013年   114篇
  2012年   168篇
  2011年   131篇
  2010年   89篇
  2009年   113篇
  2008年   68篇
  2007年   109篇
  2006年   90篇
  2005年   75篇
  2004年   62篇
  2003年   74篇
  2002年   60篇
  2001年   36篇
  2000年   41篇
  1999年   27篇
  1998年   19篇
  1997年   16篇
  1996年   18篇
  1995年   17篇
  1994年   9篇
  1993年   13篇
  1992年   7篇
  1990年   1篇
  1988年   1篇
  1986年   1篇
  1979年   1篇
  1977年   2篇
  1975年   2篇
  1974年   2篇
排序方式: 共有1943条查询结果,搜索用时 15 毫秒
21.
定量测定棉秆皮各段成分含量,并采用化学二煮法脱胶方法对棉秆皮进行分段脱胶.以棉秆皮纤维细度、残胶率、断裂强度为指标,研究脱胶处理对提取的不同段棉秆皮纤维性能的影响.结果表明,在同一脱胶工艺条件下,不同段棉杆皮纤维的细度、残胶率、断裂强度有较大差异,棉秆皮应采用分段脱胶处理.合理的棉秆皮脱胶分段方案为:第一段根部,地表以下部分;第二段中段,地表以上长度25cm;第三段稍部,地表以上长度大于25cm.  相似文献   
22.
Long‐distance drift of eggs and larvae has been identified as a possible cause of downstream displacement and poor recruitment of the endangered Rio Grande silvery minnow (Hybognathus amarus; silvery minnow). Seven experiments were conducted using artificial eggs to estimate silvery minnow egg drift and retention in the Albuquerque and Isleta reaches of the regulated Middle Rio Grande, New Mexico, USA over a range of flows during expected spawning times. Bead retention varied by reach, discharge, and shape of the hydrograph. Highest retention (6.9 and 9.7% per km in the Albuquerque and Isleta reaches, respectively) occurred on the ascending limb of a high flow in areas where there was substantial floodplain inundation. Retention was maximized at different flows in each reach (97 and 140 m3/s, respectively), possibly associated with reach‐specific floodplain inundation thresholds. Lowest retention in each reach (2.1 and 1.7%, respectively) occurred on the descending limb of low and high flows, respectively. Of the silvery minnow eggs produced in the combined Albuquerque and Isleta reaches in 2005, 8–14% are predicted to have been retained in the Albuquerque Reach (67 km) and 49–83% in the Isleta Reach (86 km) based on the distribution of adult fish and measured bead retention rates. Although silvery minnow propagules are capable of drifting long distances, our study suggests that considerable retention occurs in the Middle Rio Grande. Habitat restoration to increase channel habitat complexity, and flow management to promote floodplain inundation should help to retain a greater proportion of propagules in upstream reaches. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
23.
Differential scanning calorimetry (DSC), FTIR, X‐ray diffraction (XRD), and viscosity methods were used to examine the miscibility, interaction, and degradability of cationic guar gum (GG) and sodium carboxymethylcellulose (NaCMC) in their blend films. The experiment results prove that there exist electrostatic interactions and hydrogen bonding between GG and NaCMC. Blend films degrade quicker than pure GG or NaCMC film. Furthermore, the degradation rate of blend films is related to the interactions between GG and NaCMC. Based on the research of blend films as the drug carriers for Ibuprofen, it is found that the blend composition, initial drug concentration, and pH value affect the drug release and the GG/NaCMC blend films have good sustained release performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3553–3559, 2007  相似文献   
24.
采用草莓原果果浆制作果冻。目的是控制食品添加剂使用量,降低果冻弹性,避免因吸食果冻而造成的风险。同时由于果浆的应用,赋予产品丰富的营养。  相似文献   
25.
玉米变性淀粉压裂液稠化剂的研制   总被引:4,自引:0,他引:4  
对玉米淀粉经化学和物理变性制得变性淀粉。将该变性淀粉与少量植物胶XDF复配制成压裂液稠化剂。并对该稠化剂的理化性能、用量、复配比例以及压裂液的配方、性能和影响凝胶的因素进行了研究。结果表明:用该稠化剂配成的压裂液粘度高、流变性好、摩擦阻力小、易破胶、低残渣、低伤害,是一种适用于80℃以下低温的优良压裂液。  相似文献   
26.
田军 《现代机械》2003,(2):34-35
随着我国工业生产的迅速发展 ,桥式起重机已成为现代工业的重要工具 ,为了减少桥式起重机因啃轨而造成的自身损害和事故的发生 ,现对桥式起重机的啃轨及检查进行探讨  相似文献   
27.
Food Science and Biotechnology - Maillard-based conjugation may be a useful way of improving the functional properties of food biopolymers. In this study, covalent attachment of fish gelatin (FG)...  相似文献   
28.
In this study, a novel micro porous honeycomb structured Crg-GG-IPN material was incepted to be applicable as scaffold and accomplished. The hydrophilicity was confirmed by FT-IR and OCA. Amorphous nature and micro-rough surface were confirmed by XRD and AFM. Void fraction was 0.61?±?0.04. Void space, hemocompatibility and platelet adhesion were captured by SEM. Degradability of the material was confirmed by in-vitro degradation study. Incision method using mice model was a clear evidence for cell attachment and non-toxicity and was confirmed from hematology and histopathology. Thus, it appears that Crg-GG scaffolds can be useful as wound healing material for clinical applications.  相似文献   
29.
This study aimed to investigate the effect of flaxseed gum (FG) on the retrogradation of maize starch (MS) gels under different storage temperatures. In this work, MS‐FG gels with 0–0.4% FG were stored under different temperatures (–20, 4 and 20 °C). Under all storage temperatures, the addition of FG inhibited the retrogradation process of MS, suppressed the recrystallisation of starch molecules, reduced the water loss of starch gels and improved the texture of the gels. Among the three storage temperatures, ?20 °C could almost stop the starch retrogradation but leading it results in the hardest gel texture. The retrogradation of MS‐FG gels stored under 4 °C was most serious with the fastest rate of recrystallisation. When stored at 20 °C, the gels had a retrogradation degree that was lower than when they were stored at 4 °C and also had the softest texture.  相似文献   
30.
《Ceramics International》2017,43(18):16727-16735
Ceramic honeycomb extrusion is a technique capable of attaining high strength, porous ceramics. However, challenges prevent the realisation of its potential. These include the design of an intricate honeycomb die and the formulation of an extrudable paste. The present study addresses the latter by using guar gum (GG) as a binder. GG was rationally selected because hydrogels thereof exhibit strong shear-thinning and high stiffness properties, which are required for extrusion. Rheological analyses demonstrated ceramic pastes with similar qualities were achieved, with hydroxyapatite (HA) used as the model ceramic. The shear stiffness modulus of HA pastes was determined as 8.4 MPa with a yield stress of 1.1 kPa. Moreover, this was achieved with GG as the sole additive, which further facilitates the overall fabrication process. The binder extraction notably occurred at relatively low temperatures when other high molecular weight polymers demand temperatures above 1000 °C; therefore the latter precludes the use of ceramics with low sintering onset. The process culminated in a porous HA scaffold with similar porosity to that of a commercial HA graft, but with higher compressive strength. Lastly, the study notes that the biological and water-soluble properties of GG can broaden its application into other ceramic fabrication processes.  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