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   687篇
  免费   28篇
电工技术   8篇
化学工业   147篇
金属工艺   19篇
机械仪表   27篇
建筑科学   8篇
矿业工程   4篇
能源动力   8篇
轻工业   24篇
水利工程   15篇
石油天然气   28篇
无线电   37篇
一般工业技术   188篇
冶金工业   127篇
原子能技术   22篇
自动化技术   53篇
  2023年   9篇
  2022年   30篇
  2021年   26篇
  2020年   12篇
  2019年   9篇
  2018年   27篇
  2017年   20篇
  2016年   25篇
  2015年   22篇
  2014年   23篇
  2013年   33篇
  2012年   42篇
  2011年   30篇
  2010年   36篇
  2009年   22篇
  2008年   25篇
  2007年   28篇
  2006年   23篇
  2005年   17篇
  2004年   16篇
  2003年   13篇
  2002年   18篇
  2001年   20篇
  2000年   19篇
  1999年   9篇
  1998年   19篇
  1997年   13篇
  1996年   4篇
  1995年   10篇
  1994年   5篇
  1993年   4篇
  1992年   4篇
  1991年   8篇
  1989年   6篇
  1988年   7篇
  1987年   5篇
  1985年   5篇
  1984年   4篇
  1983年   3篇
  1979年   5篇
  1977年   3篇
  1976年   12篇
  1973年   3篇
  1972年   5篇
  1971年   4篇
  1970年   4篇
  1969年   3篇
  1968年   4篇
  1967年   4篇
  1965年   3篇
排序方式: 共有715条查询结果,搜索用时 15 毫秒
31.
Hepatocellular carcinoma (HCC) still remains a difficult to cure malignancy. In recent years, the focus has shifted to lipid metabolism for the treatment of HCC. Very little is known about hepatitis B virus (HBV) and C virus (HCV)-related hepatic lipid disturbances in non-malignant and cancer tissues. The present study showed that triacylglycerol and cholesterol concentrations were similar in tumor adjacent HBV and HCV liver, and were not induced in the HCC tissues. Higher levels of free cholesterol, polyunsaturated phospholipids and diacylglycerol species were noted in non-tumorous HBV compared to HCV liver. Moreover, polyunsaturated phospholipids and diacylglycerols, and ceramides declined in tumors of HBV infected patients. All of these lipids remained unchanged in HCV-related HCC. In HCV tumors, polyunsaturated phosphatidylinositol levels were even induced. There were no associations of these lipid classes in non-tumor tissues with hepatic inflammation and fibrosis scores. Moreover, these lipids did not correlate with tumor grade or T-stage in HCC tissues. Lipid reprogramming of the three analysed HBV/HCV related tumors mostly resembled HBV-HCC. Indeed, lipid composition of non-tumorous HCV tissue, HCV tumors, HBV tumors and HBV/HCV tumors was highly similar. The tumor suppressor protein p53 regulates lipid metabolism. The p53 and p53S392 protein levels were induced in the tumors of HBV, HCV and double infected patients, and this was significant in HBV infection. Negative correlation of tumor p53 protein with free cholesterol indicates a role of p53 in cholesterol metabolism. In summary, the current study suggests that therapeutic strategies to target lipid metabolism in chronic viral hepatitis and associated cancers have to consider disease etiology.  相似文献   
32.
The method is based on use of fluidics — an injection system for feed of feedstock and air. Introduction in asphalt production at Ryazan' Oil Refining Co. showed: equipping the oxidizing reactor with an injection system allowed obtaining viscous paving asphalts for which all parameters exceeded the requirements of GOST 22245–90, TU 38.1011356–91, and Neste specifications; stable operation of the reactor was attained in all output ranges; the injection feed system is distinguished by simplicity and reliability, and coking problems are totally eliminated; the investments are insignificant, the output of the oxidizing reactors is increased, and specific air consumption is reduced.  相似文献   
33.
In Ukraine, average and maximum concentrations of certain pollutants in inland water bodies are unacceptably high, while the number of heavy pollution accidents (one‐out effluent discharges capable of causing health hazards) is increasing. Meanwhile, the transition from a centrally planned to a free market economy is associated with severe economic downturn and a marked industrial decline. However, no comprehensive analyses related to issues linking water pollution and socio‐economic situation during the period 1991–2003 have been done. It is considered unlikely that much can be achieved to improve water quality, at the state level, in the near future. Some improvement can be achieved through changes in the system of pollution control and in public attitude, as well as obtaining relevant expertise and funds from abroad.  相似文献   
34.
Measurements of the pulse heights in the T0 start trigger detector of the ALICE experiment are necessary both for time-amplitude offline correction of start signal T0 used in the time-of-flight TOF detector and for monitoring the state of the Cherenkov counters in the detector. A high amplitude resolution is not required for these tasks; what is needed is fast encoding and interfacing with the data readout system in which only time channels are available. Therefore, amplitudes are measured in the detector by pulse-height-to-time conversion using two independent methods, one of which involves quasi-logarithmic charge-to-time converter (QTC) and the other employs two—leading-edge (LED) and constant-fraction (CFD)—timing discriminators. The main characteristics of both methods and results of calibrations of the appropriate devices using a pulsed laser are presented.  相似文献   
35.
Decomposition of lead azide (LA), pentaerythrite tetranitrate (PETN), and a laminate system composed of these substances under vibrational loading is considered. Sensitivity of these substances to impact and vibrations is determined. Sensitivity of the LA + PETN laminate system to vibrational loading, which is characterized by the degree of decomposition, is substantially higher than that of PETN, but lower than that of LA. Specific features of the mechanism of decomposition of these substances at moderate values of vibration parameters and temperatures of specimen heating are discussed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 1, pp. 73–79, January–February, 2009.  相似文献   
36.
The effects of pulsed electric fields (PEF) and osmotic impregnation in glycerol solution on the amount of unfreezable water in apple were determined by means of low-temperature differential scanning calorimetry (DSC). The obtained data were compared with behaviour of pure water–glycerol solutions (sample WG). PEF treatment was applied using a near-rectangular monopolar generator with pulse duration of 100 μs at electric field strength of 800 V/cm. The osmotic impregnation of PEF-treated apple discs was done using water–glycerol (sample AWG) and apple juice–glycerol (sample AJG) osmotic solutions at different concentration of water or juice in glycerol, W = 30–100 wt%. The data evidenced that for the PEF-treated samples the glycerol was able to penetrate successfully inside apple tissue. The state diagrams for WG, AWG and AJG samples were rather similar. It was observed that free water existed only for moisture content above some minimum value. The unfreezable water content was the largest in AJG, followed by WG and AWG. The juice concentration in glycerol W ≈ 80 wt% was found to be optimal for preservation of the texture of PEF-treated samples.  相似文献   
37.
Molecular models of all known subtypes (A1, A2A, A2B, and A3) of the human adenosine receptors were built in homology with bovine rhodopsin. These models include the transmembrane domain as well as all extracellular and intracellular hydrophilic loops and terminal domains. The molecular docking of adenosine and 46 selected derivatives was performed for each receptor subtype. A binding mode common for all studied agonists was proposed, and possible explanations for differences in the ligand activities were suggested.  相似文献   
38.
39.
Subjecting natural gas to multi-stage heating by passing it through the cooled cavities of certain tuyere elements instead of coolant water is technically simple to accomplish and makes it possible to heat the gas to 300°C or more, the exact temperature depending on the amount of gas used. The cost of instituting this technology is an order of magnitude lower than the savings realized by injecting heated natural gas into blast furnaces. The injection of heated natural gas into a blast furnace introduces additional heat into the furnace and makes it possible to use more natural gas in the smelting process without reducing the theoretical combustion temperature. It also increases the value of the coefficient that characterizes the replacement of coke by natural gas, since the gas undergoes more complete combustion in this case. Finally, the injection of heated natural gas results in a more uniform distribution of hydrogen across the furnace and allows fuller use of this element in the smelting operation.  相似文献   
40.
A thermal analysis of clays of the Gzhel' deposit is performed and their mineral composition is established. The effect of various admixtures and minerals and the dispersity on the behavior of the clays during heating is described.  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