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   2850篇
  免费   261篇
  国内免费   16篇
电工技术   4篇
综合类   285篇
化学工业   397篇
金属工艺   10篇
机械仪表   22篇
建筑科学   19篇
矿业工程   10篇
能源动力   4篇
轻工业   1931篇
水利工程   1篇
石油天然气   4篇
武器工业   1篇
无线电   130篇
一般工业技术   288篇
冶金工业   3篇
原子能技术   1篇
自动化技术   17篇
  2024年   11篇
  2023年   42篇
  2022年   78篇
  2021年   93篇
  2020年   107篇
  2019年   85篇
  2018年   67篇
  2017年   69篇
  2016年   82篇
  2015年   83篇
  2014年   120篇
  2013年   157篇
  2012年   194篇
  2011年   184篇
  2010年   117篇
  2009年   121篇
  2008年   77篇
  2007年   147篇
  2006年   117篇
  2005年   126篇
  2004年   95篇
  2003年   77篇
  2002年   81篇
  2001年   105篇
  2000年   98篇
  1999年   60篇
  1998年   60篇
  1997年   65篇
  1996年   47篇
  1995年   37篇
  1994年   60篇
  1993年   34篇
  1992年   40篇
  1991年   42篇
  1990年   49篇
  1989年   34篇
  1988年   41篇
  1987年   18篇
  1986年   2篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1977年   1篇
排序方式: 共有3127条查询结果,搜索用时 453 毫秒
11.
The work presented here discusses a new technique for preparing silk fibers and films with persistent antimicrobial activity through use of metallic dyestuffs during the fiber dyeing process. The length of the silk fibers investigated contracted when the fibers were immersed in concentrated neutral salt solutions, such as calcium or potassium nitrate, at elevated temperature levels. The birefringence and molecular orientation of the silk fibroin molecules became less ordered by the action of the neutral salt solutions, resulting in increased dyestuff absorption. Subsequently, contracted silk fibers were dyed with metallic dyestuffs containing Cr or Cu for the purpose of obtaining silk fibers with antimicrobial activity. Silk fibers dyed with metallic dyestuffs showed significant antimicrobial activity against the plant pathogen Cornebacterium and the human pathogen Coli bacillus. Tensile strength of the silk fibers after the salt shrinking and dyeing processes did not show a significant change, whereas the elongation at break was increased slightly. The techniques described here for preparing significantly active antimicrobial silk fibers are effective and economic ways of providing new materials for industrial and biomedical applications. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1181–1188, 2002  相似文献   
12.
利用腈纶废丝合成絮凝剂PAN—DCD   总被引:10,自引:0,他引:10  
本文以腈纶废丝为原料与双氰双胺在碱性溶液中反应,成功地制得含有多种活性基因的聚合物PAN-DCD,并用于染料废水脱色及炼油厂废水除油,除酚的处理研究,与常规使用的几种絮凝剂进行处理结果对照,实验结果表明:该产品单独使用处理效果明显优于其他絮凝剂,与聚铝复合使用处理效果更为理想。  相似文献   
13.
Composite films made of silk fibroin (SF) and polyallylamine (PAA) are prepared that contain various compositional ratios. These materials are analyzed to elucidate the resulting physical properties and to assess their potential toward advanced applications as industrial materials. The composite films are obtained from a SF and PAA binary system by dry casting from aqueous solution. These composite films exhibit excellent processability such as film forming capabilities, and the elongation at break is increased in the wet state. The differential scanning calorimetry (DSC) curves of the composites suggest that a mutual interaction takes place between the SF and PAA. This interaction is believed to occur because the endothermic peak, corresponding to the individual polymer, shifts with increasing SF content. The random coil conformation of the SF is present, regardless of the PAA blending, as confirmed by FTIR and DSC measurements. Additionally, living cells from Antheraea pernyi and Bombyx mori insect tissues are shown to grow effectively on the composite films. Maximum growth levels occur when the cultivation flask is coated with the material in SF/PAA ratios of 75:25 to 25:75. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1963–1970, 2002; DOI 10.1002/app.10491  相似文献   
14.
Monomer acrylic acid (AA) and initiator azo‐bis(isobutyronitrile)were carried into Antheraea pernyi silk fibroin (SF) fibers using supercritical CO2 as a solvent and carrier, followed by free radical polymerization at a suitable temperature, resulting in PAA/SF blends. The binary system of CO2/AA and the ternary system of CO2/AA/AIBN systems were studied. Different impregnation conditions, such as time, pressure, and concentration of AA in the fluid phase on mass uptake, were studied. Fourier transform infrared spectroscopy and X‐ray diffraction results confirmed that PAA was indeed present in the silk and that there were intermolecular hydrogen bonds between PAA and SF. According to thermogravimetry and DTG, blending with PAA could enhance the thermal stability of SF slightly. The water retention values indicated that the hydrophilic nature of the fibers was improved. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 864–868, 2005  相似文献   
15.
双活性基活性染料真丝绸染色工艺研究   总被引:7,自引:0,他引:7  
双活性基活性染料用于真丝绸染色有诸多影响因素:缚酸剂用碳酸氢钠比碳酸钠的固色率高用量在2%~4%,pH为8~9时最为合适:染色温度从60℃升到85℃时固色率提高3%~8%,超过85℃时易造成“灰伤”.当元明粉的用量从30g/l升到60g/l时上染率和固色率提高10%。随着浴比的增加,其固色率会有不同程度的降低,在实验条件下,浴比为1:40最好。通过上染曲线,讨论了染色过程的控制。  相似文献   
16.
长期以来,烟丝的物理特征都被认为是影响卷烟质量的主要因素。随着生产工艺和企业烟丝标准的不断提高,如今烟丝的物理特征对卷烟质量的影响不再显著。研究人员转而将目光转向了烟丝的整丝率变化率。  相似文献   
17.
通过对真丝线丝鸣整理剂的筛选、工艺探讨,拓宽了聚硅氧烷在真丝线整理上的应用,提高了真丝线产品质量  相似文献   
18.
The pedicel, nest paper, and larval silk ofPolistes annularis nests were analyzed by high-resolution solid-state [13C]NMR. The pedicel was found to have a high nitrogen content (11%), and the NMR spectra indicated that it is a mixture of carbohydrate and protein. The pedicel protein has an amino acid composition that is very rich in glycine, alanine, serine, and proline (67% of identified residues), similar to that of some insect silks. Solid-state [13C]NMR indicated that the nest paper is composed predominantly of cellulose. Silk, spun by matureP. annularis larvae, was shown by [13C] NMR and amino acid analysis to be a protein very high in serine and alanine (53%), but the amino acid composition is distinct from that of the pedicel protein.  相似文献   
19.
根据我院综合与设计性实验的课程设置情况,提出玉米须黄酮、多糖的提取、鉴别与含量测定为主题开设的综合设计性实验,此实验的开出不仅可以提高学生在有机化学、分析化学、天然药物化学、药物分析等方面的综合实验技能,将理论与实践有机地结合起来,巩固了课堂所学的理论知识,同时还可以培养学生科研创新的意识并能很好的利用"废物"。  相似文献   
20.
以柞蚕落绵为原料制备丝肽,并对其进行红外及紫外光谱分析.采用该丝肽整理棉织物,然后用艾蒿、苏木、红茶3种天然染料对整理前后的棉织物进行染色,探讨丝肽整理对棉织物天然染料染色性能的影响.结果表明:经丝肽整理后,棉织物采用3种天然染料染色的K/S值均有不同程度的提高,摩擦牢度和皂洗牢度略有下降,其中红茶Cu2+媒染样品的K/S值提高最显著,为整理前的2.24倍,其皂洗和摩擦牢度均达到3级以上.棉织物经丝肽整理后,断裂强力稍有下降,白度基本保持不变,柔软度有所改善.  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