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   1413篇
  免费   17篇
  国内免费   2篇
电工技术   41篇
化学工业   324篇
金属工艺   19篇
机械仪表   23篇
建筑科学   10篇
矿业工程   1篇
能源动力   20篇
轻工业   129篇
无线电   95篇
一般工业技术   281篇
冶金工业   328篇
原子能技术   68篇
自动化技术   93篇
  2024年   3篇
  2023年   4篇
  2022年   21篇
  2021年   21篇
  2020年   22篇
  2019年   21篇
  2018年   16篇
  2017年   15篇
  2016年   28篇
  2015年   9篇
  2014年   18篇
  2013年   59篇
  2012年   43篇
  2011年   67篇
  2010年   33篇
  2009年   46篇
  2008年   47篇
  2007年   52篇
  2006年   58篇
  2005年   52篇
  2004年   44篇
  2003年   50篇
  2002年   39篇
  2001年   28篇
  2000年   30篇
  1999年   36篇
  1998年   119篇
  1997年   82篇
  1996年   60篇
  1995年   24篇
  1994年   50篇
  1993年   30篇
  1992年   16篇
  1991年   18篇
  1990年   13篇
  1989年   17篇
  1988年   15篇
  1987年   15篇
  1986年   12篇
  1985年   12篇
  1984年   11篇
  1983年   5篇
  1982年   4篇
  1981年   10篇
  1980年   12篇
  1979年   7篇
  1978年   7篇
  1977年   5篇
  1976年   17篇
  1966年   2篇
排序方式: 共有1432条查询结果,搜索用时 31 毫秒
101.
TiO2 thin films prepared by Hot-Wire CVD method have been studied as a protecting material of transparent conducting oxide (TCO) against atomic hydrogen exposures for the fabrications of Si thin film solar cells. It was found that electrical conductivity of the films at room temperature reached a value of 0.4 S/cm. This value is 2-3 orders of magnitude higher than that of TiO2 films prepared by RF magnetron sputtering and electron-beam evaporation methods in our previous works. The conductivity improvement seems to be partly due to the enlargement of TiO2 crystallites.  相似文献   
102.
Mesoporous carbon thin films with ordered structures were prepared by using resorcinol-surfactant self-assembly. A mixture of resorcinol, surfactant, and ethanol coated on silicon substrates was exposed to formaldehyde vapor as a cross-linking agent to form structured resorcinol/formaldehyde resin films. The films were then carbonized at 800 °C in an inert atmosphere to remove the surfactant and to obtain structured carbon materials. With this vapor infiltration method, thin films with several structures were obtained from the same precursor solution by employing different vapor infiltration temperatures. The results were interpreted from the transformation of the self-assembly during the vapor infiltration process.  相似文献   
103.
This report concerns a 10-month-old infant with subtotal cor triatrium associated with left sided partial anomalous pulmonary venous connection to the innominate vein. In the operation, we found that the fossa ovalis existed between the right atrium and the accessory atrial chamber. We performed a radical operation which consisted of a resection of the intra-left-atrial diaphragma and a anastomosis of the vertical vein to the left atrium. His postoperative course was uneventful, and the result was satisfactory. We have presented and reviewed our case, and then discussed the embryogenesis and the hemodynamics. To our knowledge, our case represents the first successful surgical repair of this combination of defects in Japan.  相似文献   
104.
Oligodeoxynucleotides possessing a shortened internucleotidic linkage have been prepared using carbocyclic nucleosides lacking the 5'-methylene as the monomeric units. Specifically, the oligomers derived from carbocyclic 5'-n or thymidine and 2'-hydroxy-3'-deoxythymidine will be described.  相似文献   
105.
Phosphonium salts with different alkyl chains as substituents were incorporated covalently on the surfaces of cellulose filters with silane coupling agents containing phosphonium ions, and their surface antibacterial activities against Staphylococcus aureus and Escherichia coli were explored by the viable cell-counting method in sterile distilled water. The filters incorporating phosphonium biocides showed higher antibacterial activity, and its activity strongly depended on the structure of substituents. The surface-treated filters may be used to sterilize air and water, including microorganisms. © 1994 John Wiley & Sons, Inc.  相似文献   
106.
107.
108.
In this sensing technique, pMOS charge transfer maintains the bitline level near the GND when the plate line goes high. It gives 0.5-V higher readout voltages across the cell capacitors and enables a 0.4-V higher differential amplitude in a 512-cell per bitline structure compared with the conventional high-impedance bitline sensing technique. Using the shifted bias plate line layout, only eight cells and eight sense amplifiers per cell mat are activated, and simulations show 8.06 mW at 3 V and 5 MHz, which is about the same power consumption as the conventional device  相似文献   
109.
Helicobacter pylori and non-steroidal anti-inflammatory drugs are two of the most common causes of peptic ulceration. The aim of this review is to assess the possible inter-relationships between Helicobacter pylori and non-steroidal anti-inflammatory drugs in the pathogenesis of gastric and duodenal erosions and ulcers, with the aim of assessing if the presence of Helicobacter pylori is likely to increase the likelihood of non-steroidal anti-inflammatory drug-related gastroduodenal symptoms and lesions, and if eradication of Helicobacter pylori may reduce or prevent non-steroidal anti-inflammatory drug lesions. There appears to be more likelihood of dyspeptic symptoms in patients on long-term non-steroidal anti-inflammatory drugs when Helicobacter pylori is present. The balance of evidence also suggests that peptic ulcers and erosions in patients on long-term non-steroidal anti-inflammatory drugs may be more likely to occur in patients who are Helicobacter pylori positive compared to those who are Helicobacter pylori negative. Although Helicobacter pylori and non-steroidal anti-inflammatory drugs both increase the risk of peptic ulcer bleeding, the risk does not appear to be additive. There is increasing evidence from prospective studies that eradication of Helicobacter pylori may reduce the incidence of ulcers in patients on non-steroidal anti-inflammatory drugs. More prospective long-term studies are required. If Helicobacter pylori is confirmed to be a factor in this respect, it will aid in the targeting of patients at greatest risk of developing ulcers in patients on long-term non-steroidal anti-inflammatory drugs. Those at greatest risk are elderly patients, especially females, smokers, patients with a previous ulcer history, severe or debilitating arthritis or who have other chronic diseases. The addition of Helicobacter pylori to this list and its subsequent eradication may improve the outlook for these patients and help in the effective targeting of patients at greatest risk who are on long-term non-steroidal anti-inflammatory drugs.  相似文献   
110.
The fiber-water partition coefficient, K(fw), is decisive for performance of solid-phase microextraction (SPME) techniques in organic chemical analyses. In this study, polyacrylate (PA)-coated fiber was evaluated for its K(fw) values toward diverse neutral organic compounds. Literature K(fw) data were thoroughly evaluated, and additional K(fw) values for 69 compounds were measured in phosphate-buffered saline (PBS) solution at 37 °C. These K(fw) data, spanning over 6 orders of magnitude, were used to construct polyparameter linear free energy relationship (PP-LFER) models. The PP-LFER models fit well to the data with a standard deviation of 0.15-0.23 log units. Additional experiments indicated that the differences in temperature (25 vs 37 °C), electrolyte concentrations (pure water vs PBS), and conditioning methods (heat vs methanol) had only minor influences (<0.3 log units) on K(fw). Using the established PP-LFERs, the SPME extraction efficiency of PA coating toward compounds of differing polarity was evaluated in comparison to poly(dimethylsiloxane) (PDMS) coating. PA exhibited higher extraction capacities for H-bond donor compounds (e.g., phenols, anilines, amides, and many drugs and pesticides) with the estimated K(fw) values being 1-4 log units higher than those of PDMS. Also, PA was shown to be more efficient than PDMS for hydrophobic aromatic compounds.  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