全文获取类型
收费全文 | 20058篇 |
免费 | 2421篇 |
国内免费 | 1370篇 |
专业分类
电工技术 | 1602篇 |
技术理论 | 2篇 |
综合类 | 2572篇 |
化学工业 | 2093篇 |
金属工艺 | 304篇 |
机械仪表 | 782篇 |
建筑科学 | 2325篇 |
矿业工程 | 1144篇 |
能源动力 | 701篇 |
轻工业 | 1833篇 |
水利工程 | 1563篇 |
石油天然气 | 1236篇 |
武器工业 | 203篇 |
无线电 | 1744篇 |
一般工业技术 | 1626篇 |
冶金工业 | 723篇 |
原子能技术 | 69篇 |
自动化技术 | 3327篇 |
出版年
2024年 | 73篇 |
2023年 | 283篇 |
2022年 | 575篇 |
2021年 | 681篇 |
2020年 | 738篇 |
2019年 | 642篇 |
2018年 | 626篇 |
2017年 | 743篇 |
2016年 | 884篇 |
2015年 | 863篇 |
2014年 | 1338篇 |
2013年 | 1402篇 |
2012年 | 1529篇 |
2011年 | 1695篇 |
2010年 | 1232篇 |
2009年 | 1168篇 |
2008年 | 1133篇 |
2007年 | 1353篇 |
2006年 | 1185篇 |
2005年 | 1017篇 |
2004年 | 817篇 |
2003年 | 698篇 |
2002年 | 537篇 |
2001年 | 438篇 |
2000年 | 363篇 |
1999年 | 349篇 |
1998年 | 269篇 |
1997年 | 224篇 |
1996年 | 192篇 |
1995年 | 169篇 |
1994年 | 148篇 |
1993年 | 108篇 |
1992年 | 64篇 |
1991年 | 71篇 |
1990年 | 52篇 |
1989年 | 41篇 |
1988年 | 39篇 |
1987年 | 16篇 |
1986年 | 23篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 10篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1964年 | 2篇 |
1961年 | 2篇 |
1958年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Cadmium Sulfide and Ferrous doped Cadmium Sulfide thin films have been prepared on different substrates using an electrodeposition technique. Linear sweep voltammetric analysis has been carried out to determine deposition potential of the prepared films. X-ray diffraction analysis showed that the prepared films possess polycrystalline nature with hexagonal structure. Surface morphology and film composition have been analyzed using Scanning electron microscopy and Energy dispersive analysis by X-rays. Optical absorption analysis showed that the prepared films are found to exhibit Band gap value in the range between 2.3, 2.8 eV for Cadmium Sulfide and Ferrous doped Cadmium Sulfide. 相似文献
12.
《Energy Policy》2015
In this paper we construct an indirect measure of the supply marginal cost function for the main generators from the observed bid data in the Italian electricity market in the period 2004–2007. We compute the residual demand function for each generator, taking explicitly into account the issue of transmission line congestion. This procedure allows recovering correct zonal Lerner index and the implied measure of the marginal cost function. We find evidence of a stable U-shaped marginal cost function for three main Italian generators, but a flat function for ENEL, the former national monopolist. The policy relevance of our approach lies in the possibility to offer some empirical knowledge of the marginal cost function of each generator to the regulator to design appropriate policy measures geared to the promotion of competitive market conditions. We propose a new market surveillance mechanism, which is based on the principle of sanctioning excessive deviations from the estimated measure of the marginal cost function presented in this work. 相似文献
13.
Metamerism phenomenon can be used in illuminant detection to ensure the accuracy of light source. A method based on Long‐, Middle‐, Short‐ wavelength cones(LMS) weighting algorithm to evaluate metamerism degree is proposed. The chromatic relationship between the degree of metamerism mismatch and the light source is studied. Herein, the consistency between the metameric indices (MIs) and CIE1976 L*a*b* color difference ranking is analyzed by SRCC, KRCC, PLCC and RMSE. A statistically sampling method to obtain practical LMS cone fundamentals to evaluate metamerism degree is employed. The analysis results obtained show that the method based on LMS weighting algorithm has good evaluation ability and stability in simulation experiments and statistically sampling experiments, which are in line with visual characteristics of human. Proposed method meets the requirements of selecting metameric pairs used in light source detection. The analysis results have certain guiding significance. 相似文献
14.
Greenish yellow organic light-emitting diodes (GYOLEDs) have steadily attracted researcher's attention since they are important to our life. However, their performance significantly lags behind compared with the three primary colors based OLEDs. Herein, for the first time, an ideal host-guest system has been demonstrated to accomplish high-performance phosphorescent GYOLEDs, where the guest concentration is as low as 2%. The GYOLED exhibits a forward-viewing power efficiency of 57.0 lm/W at 1000 cd/m2, which is the highest among GYOLEDs. Besides, extremely low efficiency roll-off and voltages are achieved. The origin of the high performance is unveiled and it is found that the combined mechanisms of host-guest energy transfer and direct exciton formation on the guest are effective to furnish the greenish yellow emission. Then, by dint of this ideal host-guest system, a simplified but high-performance hybrid white OLED (WOLED) has been developed. The WOLED can exhibit an ultrahigh color rendering index (CRI) of 92, a maximum total efficiency of 27.5 lm/W and a low turn-on voltage of 2.5 V (1 cd/m2), unlocking a novel avenue to simultaneously achieve simplified structure, ultrahigh CRI (>90), high efficiency and low voltage. 相似文献
15.
根据洗浴废水的水质特征,采用原水→混凝沉淀-过滤→固定化生物活性炭(Immobilized Biological Activated Carbon,IBAC)→微滤膜(MF)→UV消毒→出水的工艺流程.混凝沉淀-过滤物化预处理单元可以有效地减少洗浴废水中的各类污染物.IBAC生化处理单元,实现有机污染物、LAS、浴臭等有效去除,是保证出水合格的根本措施.微滤膜发挥物理截留作用、UV消毒杀死细菌和总大肠菌群.出水水质达到<城市供水水质标准>(CJ/T 206-2005). 相似文献
16.
17.
18.
19.
20.
大坝安全监控指标的制定 总被引:10,自引:3,他引:7
本文论述了大坝安全监控指标的含义、制定安全监控指标的意义、制定安全监控指标的基本原则、制定大坝施工阶段和首次蓄水阶段以及运行阶段安全监控指标的方法。 相似文献