全文获取类型
收费全文 | 260920篇 |
免费 | 4266篇 |
国内免费 | 1820篇 |
专业分类
电工技术 | 5415篇 |
技术理论 | 5篇 |
综合类 | 1164篇 |
化学工业 | 42055篇 |
金属工艺 | 11021篇 |
机械仪表 | 7742篇 |
建筑科学 | 6593篇 |
矿业工程 | 1660篇 |
能源动力 | 5594篇 |
轻工业 | 25800篇 |
水利工程 | 2890篇 |
石油天然气 | 5998篇 |
武器工业 | 243篇 |
无线电 | 27793篇 |
一般工业技术 | 49200篇 |
冶金工业 | 47285篇 |
原子能技术 | 5616篇 |
自动化技术 | 20932篇 |
出版年
2021年 | 2476篇 |
2019年 | 2121篇 |
2018年 | 3386篇 |
2017年 | 3357篇 |
2016年 | 3686篇 |
2015年 | 2800篇 |
2014年 | 4580篇 |
2013年 | 11355篇 |
2012年 | 7694篇 |
2011年 | 10199篇 |
2010年 | 8114篇 |
2009年 | 8671篇 |
2008年 | 9475篇 |
2007年 | 9594篇 |
2006年 | 8436篇 |
2005年 | 7388篇 |
2004年 | 6654篇 |
2003年 | 6201篇 |
2002年 | 6210篇 |
2001年 | 6319篇 |
2000年 | 5907篇 |
1999年 | 5879篇 |
1998年 | 12878篇 |
1997年 | 9550篇 |
1996年 | 7287篇 |
1995年 | 5533篇 |
1994年 | 5085篇 |
1993年 | 4950篇 |
1992年 | 3945篇 |
1991年 | 3753篇 |
1990年 | 3823篇 |
1989年 | 3773篇 |
1988年 | 3532篇 |
1987年 | 3019篇 |
1986年 | 3053篇 |
1985年 | 3410篇 |
1984年 | 3326篇 |
1983年 | 3076篇 |
1982年 | 2700篇 |
1981年 | 2902篇 |
1980年 | 2643篇 |
1979年 | 2839篇 |
1978年 | 2736篇 |
1977年 | 2842篇 |
1976年 | 3697篇 |
1975年 | 2458篇 |
1974年 | 2290篇 |
1973年 | 2320篇 |
1972年 | 1981篇 |
1971年 | 1786篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
N Ferrara G Longobardi N Guerra A Nicolino D Acanfora G Furgi L Odierna R Rosiello F Rengo 《Canadian Metallurgical Quarterly》1996,34(1-2):37-41
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
104.
105.
106.
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
107.
L Struillou M Fiks-Sigaud JH Barrier E Blat G Magadur-Joly 《Canadian Metallurgical Quarterly》1993,60(7-8):524-526
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
108.
Neusser S. Nijhuis J. Spaanenburg L. Hoefflinger B. Franke U. Fritz H. 《Micro, IEEE》1993,13(1):57-66
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
109.
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
110.
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