全文获取类型
收费全文 | 15651篇 |
免费 | 2814篇 |
国内免费 | 1801篇 |
专业分类
电工技术 | 1151篇 |
综合类 | 1256篇 |
化学工业 | 776篇 |
金属工艺 | 509篇 |
机械仪表 | 1374篇 |
建筑科学 | 302篇 |
矿业工程 | 250篇 |
能源动力 | 440篇 |
轻工业 | 325篇 |
水利工程 | 107篇 |
石油天然气 | 159篇 |
武器工业 | 365篇 |
无线电 | 2912篇 |
一般工业技术 | 1045篇 |
冶金工业 | 380篇 |
原子能技术 | 634篇 |
自动化技术 | 8281篇 |
出版年
2024年 | 220篇 |
2023年 | 567篇 |
2022年 | 1018篇 |
2021年 | 1033篇 |
2020年 | 796篇 |
2019年 | 606篇 |
2018年 | 501篇 |
2017年 | 571篇 |
2016年 | 683篇 |
2015年 | 736篇 |
2014年 | 1067篇 |
2013年 | 1071篇 |
2012年 | 1049篇 |
2011年 | 1236篇 |
2010年 | 858篇 |
2009年 | 957篇 |
2008年 | 981篇 |
2007年 | 1027篇 |
2006年 | 901篇 |
2005年 | 862篇 |
2004年 | 644篇 |
2003年 | 542篇 |
2002年 | 448篇 |
2001年 | 301篇 |
2000年 | 233篇 |
1999年 | 232篇 |
1998年 | 182篇 |
1997年 | 147篇 |
1996年 | 107篇 |
1995年 | 85篇 |
1994年 | 101篇 |
1993年 | 79篇 |
1992年 | 53篇 |
1991年 | 54篇 |
1990年 | 76篇 |
1989年 | 48篇 |
1988年 | 20篇 |
1987年 | 22篇 |
1986年 | 33篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 30篇 |
1981年 | 21篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1964年 | 2篇 |
1959年 | 3篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
The paper concerns an analysis of an equilibrium problem for 2D elastic body with two semirigid inclusions. It is assumed that inclusions have a joint point, and we investigate a junction problem for these inclusions. The existence of solutions is proved, and different equivalent formulations of the problem are proposed. We investigate a convergence to infinity of a rigidity parameter of the semirigid inclusion. It is proved that in the limit, we obtain an equilibrium problem for the elastic body with a rigid inclusion and a semirigid one. A parameter identification problem is investigated. In particular, the existence of a solution to a suitable optimal control problem is proved. 相似文献
13.
This study is to evaluate the potential for development of a cellulosic ethanol facility in Vietnam. Rice straw is abundant in Vietnam and highly concentrated in the Mekong Delta, where about 26 Mt year−1 of rice straw has been yearly produced. To minimize the overall production cost (PC) of ethanol from rice straw, it is crucial to choose the optimal facility size. The delivered cost of rice straw varied from 20.5 to 65.4 $ dry t−1 depending on transportation distance. The Mekong Delta has much lower rice straw prices compared with other regions in Vietnam because of high density and quantity of rice straw supply. Thus, this region has been considered as the most suitable location for deploying ethanol production in Vietnam. The optimal plant size of ethanol production in the region was estimated up to 200 ML year−1. The improvement in solid concentration of material in the hydrothermal pre-treatment step and using residues for power generation could substantially reduce the PC in Vietnam, where energy costs account for the second largest contribution to the PC, following only enzyme costs. The potential for building larger ethanol plants with low rice straw costs can reduce ethanol production costs in Vietnam. The current estimated production cost for an optimal plant size of 200 ML year−1 was 1.19 $ L−1. For the future scenario, considering improvements in pre-treatment, enzyme hydrolysis steps, specific enzyme activity, and applying residues for energy generation, the ethanol production cost could reduce to 0.45 $ L−1 for a plant size of 200 ML year−1 in Vietnam. These data indicated that the cost-competitiveness of ethanol production could be realized in Vietnam with future improvements in production technologies. 相似文献
14.
针对基于规则和统计的传统中文简历解析方法效率低、成本高、泛化能力差的缺点,提出一种基于特征融合的中文简历解析方法,即级联Word2Vec生成的词向量和用BLSTM(Bidirectional Long Short-Term Memory)建模字序列生成的词向量,然后再结合BLSTM和CRF(Conditional Random Fields)对中文简历进行解析(BLSTM-CRF)。为了提高中文简历解析的效率,级联包含字序列信息的词向量和用Word2Vec生成的词向量,融合成一个新的词向量表示;再由BLSTM强大的学习能力融合词的上下文信息,输出所有可能标签序列的分值给CRF层;再由CRF引入标签之间约束关系求解最优序列。利用梯度下降算法训练神经网络,使用预先训练的词向量和Dropout优化神经网络,最终完成对中文简历的解析工作。实验结果表明,所提的特征融合方法优于传统的简历解析方法。 相似文献
15.
In this paper, we proposed a robust discrete-time controller. This control system, which is derived from the idea of the normalized plant, does not include plant parameters. Thus, we obtain a control system independent of plant parameters and that has the same structure as a conventional optimal servo control system. Simulation and experimental results show that the proposed method is fairly robust to plant parameter variations and external disturbances. 相似文献
16.
入侵检测是保障网络安全的重要手段,针对现有入侵检测系统中告警数量多、协调性差等问题,论文提出了一种具有告警融合与关联功能的告警处理系统模型,该模型冗余告警量少、整体检测能力强,并能进行攻击企图的预测,能有效提高入侵检测的效率,有助于进一步增强网络的健壮性。 相似文献
17.
介绍一种用于经纬仪引导数据的处理方法。该方法利用参数估计法对引导数据进行融合,弥补了常规方法的不足。对经纬仪引导数据进行处理,结果表明,该方法可显著提高经纬仪的引导精度,引导误差小于0.50m。 相似文献
18.
19.
20.
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