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   261477篇
  免费   4613篇
  国内免费   1879篇
电工技术   5593篇
技术理论   5篇
综合类   1242篇
化学工业   42084篇
金属工艺   11042篇
机械仪表   7829篇
建筑科学   6624篇
矿业工程   1705篇
能源动力   5620篇
轻工业   26073篇
水利工程   2900篇
石油天然气   6007篇
武器工业   279篇
无线电   27865篇
一般工业技术   49253篇
冶金工业   47264篇
原子能技术   5624篇
自动化技术   20960篇
  2021年   2552篇
  2019年   2186篇
  2018年   3439篇
  2017年   3425篇
  2016年   3765篇
  2015年   2838篇
  2014年   4606篇
  2013年   11392篇
  2012年   7705篇
  2011年   10210篇
  2010年   8134篇
  2009年   8691篇
  2008年   9493篇
  2007年   9600篇
  2006年   8444篇
  2005年   7396篇
  2004年   6664篇
  2003年   6212篇
  2002年   6211篇
  2001年   6321篇
  2000年   5911篇
  1999年   5882篇
  1998年   12869篇
  1997年   9544篇
  1996年   7292篇
  1995年   5528篇
  1994年   5084篇
  1993年   4953篇
  1992年   3944篇
  1991年   3752篇
  1990年   3826篇
  1989年   3769篇
  1988年   3531篇
  1987年   3022篇
  1986年   3051篇
  1985年   3409篇
  1984年   3323篇
  1983年   3074篇
  1982年   2700篇
  1981年   2903篇
  1980年   2643篇
  1979年   2839篇
  1978年   2737篇
  1977年   2841篇
  1976年   3694篇
  1975年   2459篇
  1974年   2291篇
  1973年   2320篇
  1972年   1981篇
  1971年   1785篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
We prospectively studied 10 patients with stable exertional ischaemia, selected from a larger group of patients referred for suspected coronary artery disease or to detect residual ischaemia after myocardial infarction, to evaluate pharmacokinetic changes during chronic treatment with gallopamil and its correlation with clinical efficacy in patients with coronary artery disease. Our study consisted of a 1-week run-in single-blind placebo treatment and a 4-week single-blind gallopamil treatment. At the end of the run-in period patients underwent two different exercise tests, the first 2 hours and the second 7 hours after placebo administration. During active treatment all patients underwent two different exercise tests, the first 2 hours and the second 7 hours after gallopamil (50 mg) administration on the 1st and 28th days of gallopamil therapy. On the same days in eight of the patients we evaluated gallopamil pharmacokinetic changes. Our data revealed a rapid increase of unchanged gallopamil and its metabolite (norgallopamil) in the plasma, and a peak concentration of these substances about 2 hour after oral administration on both the 1st and 28th day of observation. Moreover, our results demonstrated an increase between the first and 28th day of treatment in peak concentration of unchanged gallopamil in the plasma, and of AUC 0-infinity and AUC o-c values during chronic treatment with gallopamil. Our clinical data showed an improvement in exercise results during gallopamil therapy related to increased concentration of the drug.  相似文献   
103.
104.
105.
A Biologically-Parameterized Feather Model   总被引:1,自引:0,他引:1  
Feathers, unlike other cutaneous appendages such as hair, fur, or scales have a definite structure. Variation in feather structure creates a wide range of resulting appearances. Collectively, feather structure determines the appearance of the feather coat, which can largely affect the resulting look of a feathered object (bird). In this paper we define the structure of individual feathers using a parameterization based on biological structure and substructures of actual feathers. We show that our parameterization can generate a large variety of feathers at multiple levels of detail and provide an initial step to semi‐automatically generating a wide range of feather coats. his is achieved by specifying an intuitive interpolation between different structures and ages of feathers.  相似文献   
106.
The authors report an exceedingly rare complication of rheumatoid arthritis, i.e. acquired hemophilia due to anti-factor VIII autoantibody production. Treatment with intravenous immune globulin ensured control of hemorrhagic manifestations by inducing a transient rise in factor VIII level.  相似文献   
107.
A solution to autonomous lateral vehicle guidance using a neurocontroller that can learn from measured human-driving data without knowledge of the physical car parameters is discussed. Simulations and practical tests confirm that a small-size feedforward autonomous neural network (21 neurons) can learn to steer a vehicle at high speeds only from looking at human-driving examples. In this way, the network learns the total closed-loop behavior, including the nonlinear dynamics of the vehicle and the driver's individual driving style. The main result of practical investigations is that the neutral controller trained on human-driving examples exhibits an aperiodic behavior that does not vanish at higher speeds (tests performed up to 130 km/h) and produces fewer lateral deviations than the linear state controller  相似文献   
108.
Following two years operation of the 100 kW grid-connected installation N13 near Domat/Ems, Switzerland, considerable data are available. The yield of the installation was calculated on the basis of long-term meteorological data and of the Meteonorm model. The findings show a close correlation between the forecast and the measured yields. With 100% availability of the inverter in 1991, the performance of the installation rose from 59% in 1990 to 79% in 1991. With standardized analysis of the data, the performance of the grid-connected installation N13 can be compared with other grid-connected installations irrespective of size and location.  相似文献   
109.
Methods are described for forming coating specimens and testing them in pure bending. The proposed tester gives adequate accuracy in determining the elastic characteristics and strength for thin specimens (up to 0.1 mm) of brittle materials of powder-coating type.Translated from Problemy Prochnosti, No. 3, pp. 94–97, March, 1993.  相似文献   
110.
Professional software engineering continues to face problems that involve large-scale (complex) software systems development. Such efforts typically require team collaboration over months, possibly years. Once implemented, the system must be maintained for sometimes decades. This development and maintenance life cycle requires not only technical knowledge and skills in software development, but also the knowledge and skills associated with software process. We believe the traditional computer science curriculum fails to consider this spectrum of needs. We also believe, however, that software engineering must use certain elements of the core knowledge and skills taught by computer scientists as its foundation. We describe lessons learned from the 10-year collaboration between Monmouth University and the Software Engineering Center of the US Army's CECOM (Communications Electronics Command). The center recruits electrical engineering and computer science graduates from academic institutions in the geographic regions surrounding its various installations to be part of its intern program; Monmouth University, in turn, incorporates the demands of the intern program in its Master of Science in software engineering curriculum  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