全文获取类型
收费全文 | 40371篇 |
免费 | 3025篇 |
国内免费 | 1782篇 |
专业分类
电工技术 | 2051篇 |
技术理论 | 3篇 |
综合类 | 4811篇 |
化学工业 | 4900篇 |
金属工艺 | 1475篇 |
机械仪表 | 1533篇 |
建筑科学 | 7455篇 |
矿业工程 | 2262篇 |
能源动力 | 1107篇 |
轻工业 | 3164篇 |
水利工程 | 2011篇 |
石油天然气 | 2055篇 |
武器工业 | 175篇 |
无线电 | 2210篇 |
一般工业技术 | 3448篇 |
冶金工业 | 2498篇 |
原子能技术 | 355篇 |
自动化技术 | 3665篇 |
出版年
2024年 | 161篇 |
2023年 | 545篇 |
2022年 | 939篇 |
2021年 | 1149篇 |
2020年 | 1035篇 |
2019年 | 921篇 |
2018年 | 822篇 |
2017年 | 985篇 |
2016年 | 1103篇 |
2015年 | 1192篇 |
2014年 | 2221篇 |
2013年 | 1977篇 |
2012年 | 2577篇 |
2011年 | 2775篇 |
2010年 | 2202篇 |
2009年 | 2371篇 |
2008年 | 2128篇 |
2007年 | 2781篇 |
2006年 | 2548篇 |
2005年 | 2279篇 |
2004年 | 1930篇 |
2003年 | 1795篇 |
2002年 | 1520篇 |
2001年 | 1273篇 |
2000年 | 1067篇 |
1999年 | 862篇 |
1998年 | 616篇 |
1997年 | 535篇 |
1996年 | 464篇 |
1995年 | 434篇 |
1994年 | 327篇 |
1993年 | 281篇 |
1992年 | 223篇 |
1991年 | 147篇 |
1990年 | 162篇 |
1989年 | 143篇 |
1988年 | 119篇 |
1987年 | 94篇 |
1986年 | 63篇 |
1985年 | 60篇 |
1984年 | 50篇 |
1983年 | 24篇 |
1982年 | 23篇 |
1981年 | 32篇 |
1980年 | 28篇 |
1979年 | 35篇 |
1977年 | 17篇 |
1976年 | 18篇 |
1975年 | 20篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
The supervision of a hybrid power plant, including solar panels, a gas microturbine and a storage unit operating under varying solar power profiles is considered. The Economic Supervisory Predictive controller assigns the power references to the controlled subsystems of the hybrid cell using a financial criterion. A prediction of the renewable sources power is embedded into the supervisor. Results deteriorate when the solar power is unsteady, owing to the inaccuracy of the predictions for a long-range horizon of 10 s. The receding horizon is switched between an upper and a lower value according to the amplitude of the solar power trend. Theoretical results show the relevance of horizon switching, according to a tradeoff between performance and prediction accuracy. Experimental results, obtained in a Hardware In the Loop (HIL) framework, show the relevance of the variable horizon approach. Power amplifiers allow us to simulate virtual components, such as a gas microturbine, and to blend their powers with that of real devices (storage unit, real solar panels). In this case, fuel savings, reaching 15%, obtained under unsteady operating conditions lead to a better overall performance of the hybrid cell. The overall savings obtained in the experiments amount to 12%. 相似文献
2.
Measuring nonlinear optical response of a specific material in a mixture, not only leads to investigate the behavior of a particular component in various circumstances, but also can be a way to select suitable combination and optimum concentration of additives and therefore obtaining the maximum nonlinear optical signals. In this work, by using dual-arm Z-scan technique, the nonlinear refractive index of Disperse Red1 (DR1) organic dye molecules inside the core of prepared polymeric nanocapsules was measured among various materials which prepared nanocapsules were made of them. Then the measured value was compared with nonlinear refractive index of DR1 solved in dichloromethane. 相似文献
3.
文章中主要采用有机溶剂萃取法(OSE)对高浓度石油污染土壤进行修复,经过精馏操作,有效回收原油,建立脱附等温曲线,研究了石油污染物在土壤-有机溶剂两相间的迁移规律。 相似文献
4.
5.
针对辽河油区超稠油采油污水的特点,采用Fenton试剂催化氧化,对采油污水处理进行研究。实验研究及现场应用结果表明,此方法对污水的CODCr具有良好的去除效果。处理后污水经过简单生化,进一步降解污染物,能够实现稳定迭标排放,且具有能耗低、运行成本低和操作简单等特点。 相似文献
6.
The problem of operating freeze drying of pharmaceutical products in vials placed in trays of a freeze dryer to remove free water (in frozen state) at a minimum time was formulated as an optimal control problem. Two different types of freeze dryer designs were considered. In type I freeze dryer design, upper and lower plate temperatures were controlled together, while in type II freeze dryer design, upper and lower plate temperatures were controlled independently. The heat input to the material being dried and the drying chamber pressure were considered as control variables. Constraints were placed on the system state variables by the melting and scorch temperatures during primary drying stage. Necessary conditions of optimality for the primary drying stage of freeze drying process in vials are derived and presented. Furthermore, an approach for constructing the optimal control policies that would minimize the drying time for the primary drying stage was given. In order to analyze optimal control policy for the primary drying stage of the freeze-drying process in vials, a rigorous multi-dimensional unsteady state mathematical model was used. The theoretical approach presented in this work was applied in the freeze drying of skim milk. Significant reductions in the drying times of primary drying stage of freeze drying process in vials were obtained, as compared to the drying times obtained from conventional operational policies. 相似文献
7.
五.牛奶厂的清洗。目前,牛奶厂采用的清洗方式主要是CIP清洗(Cleaning in place),原地清洗或称定置清洗,即在基本不拆卸或挪动机械装置和管线的情况下对生产过程中能与牛奶发生接触的设备表面进行的清洗。其冲刷、清洗、灭菌的整个过程全部实现了自动化因此大大降低了劳动强度。而有一些不 相似文献
8.
套保稠油油田火烧油层可行性分析 总被引:2,自引:1,他引:1
从火烧油层的筛选标准、实际地质条件及室内物理模拟实验入手,对该油田火烧可行性进行了分析。分析结果认为,套保油田进行火烧总体上是可行的,在实际火烧时应避开底水的影响,火烧区域应选在构造高部位或仅烧其主力层。 相似文献
9.
在大空间的温度控制系统中 ,采用简单的PID控制规律 ,对空间的温度、湿度进行解藕计算 ,将空间的相对湿度控制转化为送风含湿量的控制。该控制方式稳定、可靠 ,并且节约能源。本方法适用于所有的烘烤炉中 相似文献
10.
I. S. W. B. Prasetya 《Formal Aspects of Computing》1994,6(4):466-470
UNITY, introduced by Chandy and Misra [ChM88], is a programming logic intended to reason about temporal properties of distributed programs. Despite the fact that UNITY does not have the full power of, for example, linear temporal logic, it enjoys popularity due to its simplicity.There was however a serious problem with the Substitution Rule. The logic is incomplete without the rule, and with the rule it is inconsistent. 相似文献