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   572篇
  免费   58篇
  国内免费   19篇
电工技术   27篇
综合类   42篇
化学工业   52篇
金属工艺   1篇
机械仪表   18篇
建筑科学   2篇
能源动力   2篇
轻工业   31篇
石油天然气   2篇
武器工业   9篇
无线电   270篇
一般工业技术   6篇
原子能技术   1篇
自动化技术   186篇
  2024年   1篇
  2022年   4篇
  2021年   15篇
  2020年   12篇
  2019年   3篇
  2018年   3篇
  2017年   10篇
  2016年   15篇
  2015年   20篇
  2014年   31篇
  2013年   26篇
  2012年   45篇
  2011年   54篇
  2010年   52篇
  2009年   47篇
  2008年   48篇
  2007年   52篇
  2006年   51篇
  2005年   58篇
  2004年   21篇
  2003年   22篇
  2002年   25篇
  2001年   17篇
  2000年   5篇
  1999年   5篇
  1998年   2篇
  1995年   3篇
  1994年   1篇
  1984年   1篇
排序方式: 共有649条查询结果,搜索用时 390 毫秒
101.
Lekhal S  Børvik T  Nordøy A  Hansen JB 《Lipids》2008,43(6):507-515
Postprandial triglyceride-rich lipoproteins (TRL) levels are a predictor for coronary atherosclerosis. The aim of the study was to compare fasting high density lipoprotein (HDL) cholesterol, plasma lipoprotein lipase (LPL) activity, and postprandial TRL between elderly survivors of myocardial infarction (MI) and healthy controls. A case-control study was performed in 44 elderly patients 65-85 years of age with a previous history of MI and 43 age- and sex-matched healthy controls. Each participant underwent physical examination and was given a standard oral fat load with subsequent blood sampling over the next 8 h. Total and chylomicron triglycerides were assessed by area under the curve (AUC), incremental are under the curve (AUCi) and triglyceride response (TGR). Elderly MI patients had significantly lower postheparin LPL activity (87.4 +/- 36.9 mU/ml) (mean +/- 1 SD) than healthy controls (106.0 +/- 29.0 mU/ml) (P = 0.014). Decreased postheparin LPL activity was accompanied by significant increased and delayed clearance of postprandial TRL. Fasting HDL cholesterol was significantly lower in elderly MI patients than controls (1.45 +/- 0.32 and 1.66 +/- 0.47 mmol/l, respectively, P = 0.048). Multiple regression analysis revealed postheparin LPL activity as an independent predictor for postprandial TRL and fasting HDL cholesterol. Logistic regressions analysis revealed HDL cholesterol, triglycerides measured 2 h after the oral fat load, and postheparin LPL activity as independent predictors for MI. Our findings indicate that decreased fasting HDL cholesterol is associated with increased postprandial triglyceridemia which could be a target for life-style and therapeutic interventions in patients at risk for cardiovascular disease.  相似文献   
102.
Background and aims: To investigate the impact of plasma apoA‐II concentrations on the alteration of HDL subclass distribution, and the cooperative effect of apoA‐I and apoA‐II on it. Methods and results: The apoA‐I contents of plasma HDL subclasses were quantified by two‐dimensional gel electrophoresis associated with immunodetection for 292 Chinese people. These subjects were divided according to the mean ± 1 SD of apoA‐II and apoA‐I levels as two cut‐points, respectively. Compared with the low‐apoA‐II group, the apoA‐I contents of HDL3a (in the high group), HDL3b, and HDL2b increased strikingly, both in the middle‐ and high‐apoA‐II group. The apoA‐I contents of all HDL subclasses increased progressively when the apoA‐I and apoA‐II levels simultaneously or the apoA‐I/apoA‐II ratio increased, and in comparison to the low‐apoA‐I–A‐II levels group, the apoA‐I contents of HDL2b (115%) increased more significantly than those of preβ1HDL (39%) in the high‐apoA‐I–A‐II levels group. Multiple analyses also indicated that the three HDL subclasses, HDL3a, HDL3b and HDL2b, were independently predicted by apoA‐II. Conclusion: Excess apoA‐II can cause the accumulation of both large‐sized HDL2b and small‐sized HDL3, which implies that apoA‐II plays a double role in the HDL maturation metabolism. Meanwhile, the degree of HDL2b increased significantly relative to that of preβ1HDL when apoA‐I and apoA‐II levels were elevated simultaneously, suggesting that the maturation and metabolism of HDL might be promoted and reverse cholesterol transport might be enhanced.  相似文献   
103.
基于可综合风格的Verilog HDL技术,采取控制单元与数据通道分离的设计结构,对320×256红外焦平面阵列的开窗寻址电路进行RTL级建模,设计了具有对红外焦平面阵列任意开窗寻址功能和读出顺序可上下左右翻转功能的寻址电路。并在Cadence NC Verilog环境下进行编译与仿真,仿真结果表明整个设计能够实现预期寻址功能,满足IRFPA读出多样化的需求。  相似文献   
104.
张洪亮 《电讯技术》2012,52(6):1022-1026
针对现有的航空总线系统结构复杂、传输速率低、电磁兼容性差等问题,提出了一种基于FPGA的总线型低压差分信号(BLVDS)总线解决方案.介绍了BLVDS的总线结构,对BLVDS的通信方式和基于FPGA使用硬件描述语言实现BLVDS总线通信的方法进行了深入研究.同时,分析了信号传输质量,在工程中验证了其高速率和高可靠的总线传输特性,为新一代航空高速总线系统提供了参考.  相似文献   
105.
谢海霞 《电子器件》2012,35(2):232-235
介绍了FIR滤波器的基本的线性相位结构及FIR滤波器的抽头系数SD算法编码。给定滤波器的数字指标,用MATLB设计抽头系数,最后用Verilog HDL语言实现了一个16阶的FIR低通滤波器并在QuartusⅡ上仿真,并对仿真结果与理论值进行比较,波形仿真结果和理论值相吻和,最后将编程数据文件下载到FPGA芯片上。对于不同性能的FIR滤波器,抽头系数是变化的,因此只要对本设计的抽头系数重新在线配置,就可以实现不同的FIR滤波器。  相似文献   
106.
基于Xilinx FPGA的SPI Flash控制器设计与验证   总被引:1,自引:0,他引:1       下载免费PDF全文
关珊珊  周洁敏 《电子器件》2012,35(2):216-220
基于Xilinx FPGA的SPI Flash控制器实现了一种在线配置Flash的方法。由于Flash芯片本身功能指令较多,使得对它进行直接操作变得非常困难,而利用FPGA丰富的逻辑资源以及产生精确时序的能力,以FPGA为主设备,SPI Flash为从设备,使FPGA一方面与电脑串口通信获得数据,另一方面对SPI Flash进行控制,这样就完成了FPGA配置数据的控制和存储。  相似文献   
107.
陶佰睿  苗凤娟  张景林  张琳 《微电子学》2012,42(3):383-387,392
利用Quartus Ⅱ和ModelSim软件,基于EP2C35芯片FPGA开发平台,通过Verilog-HDL语言,完成了O-QPSK调制解调器的设计。该设计具有结构简单、占用芯片面积少、便于生成IP核等优点。电路与系统的仿真结果表明,所预期的功能均已实现,该方法适合在无线传感器网络及低功耗通信集成电路设计中应用。  相似文献   
108.
基于Verilog HDL语言的CAN总线控制器设计及验证   总被引:2,自引:2,他引:0  
在此利用Verilog HDL设计了一款CAN总线控制器,首先根据协议把整个CAN总线控制器划分为接口逻辑管理、寄存器逻辑和CAN核心模块3个模块,然后用Verilog HDL硬件描述语言设计了各个功能模块,并使用Modelsim软件对各个模块的功能进行了仿真,最后使用FPGA芯片对设计的CAN总线控制器验证,并连接了一个包含该FPGA CAN总线控制器的4节点CAN总线网络。测试结果表明所设计的CAN总线控制器能够完成设定的功能。  相似文献   
109.
Naureen Shahzadi  Muhammad Nasir 《LWT》2007,40(7):1198-1205
The aim of the study was to probe the hypocholesterolemic effect of legumes dietary fiber through “chapaties” a staple diet of the South Asia. Commercial wheat flour (atta) was blended with legumes i.e. lentil, chickpea and guar gum in various combinations to make composite flour for the preparation of chapaties. Maximum dietary fiber (8.85%) was observed in composite flour with 3g/100 g guar gum, which also gave whiter look and puffiness to the end product. Highest percent increase in dietary fiber (35.3%) was in flour with 3g/100 g guar gum followed by guar gum 2g/100 g (24.1%). The diets prepared from three best selected compositions along with control, were fed to male Sprague Dawley rats for 8 weeks. Lowest serum cholesterol (82.46 mg/dl) was observed in rats fed on guar gum 3g/100 g which showed a significant reduction (17.2%) as compared to control. Similarly, in case of LDL and triglycerides, guar gum 3 g/100 g showed highest decline i.e., 29.7% and 28.4% with reference to control, respectively. The present investigation suggests that five chapaties per day prepared from selected compositions provides an extra 5-8 g of dietary fiber that is helpful in lowering cholesterol in hypercholesterolemic individuals.  相似文献   
110.
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