全文获取类型
收费全文 | 314487篇 |
免费 | 27135篇 |
国内免费 | 18949篇 |
专业分类
电工技术 | 17787篇 |
技术理论 | 51篇 |
综合类 | 42567篇 |
化学工业 | 33311篇 |
金属工艺 | 15450篇 |
机械仪表 | 17690篇 |
建筑科学 | 51102篇 |
矿业工程 | 20958篇 |
能源动力 | 9133篇 |
轻工业 | 16414篇 |
水利工程 | 17296篇 |
石油天然气 | 17028篇 |
武器工业 | 2903篇 |
无线电 | 17774篇 |
一般工业技术 | 25428篇 |
冶金工业 | 18340篇 |
原子能技术 | 2974篇 |
自动化技术 | 34365篇 |
出版年
2024年 | 498篇 |
2023年 | 2900篇 |
2022年 | 5710篇 |
2021年 | 7873篇 |
2020年 | 7796篇 |
2019年 | 6726篇 |
2018年 | 6282篇 |
2017年 | 7616篇 |
2016年 | 9068篇 |
2015年 | 9978篇 |
2014年 | 17852篇 |
2013年 | 16656篇 |
2012年 | 21363篇 |
2011年 | 22910篇 |
2010年 | 17971篇 |
2009年 | 18779篇 |
2008年 | 17479篇 |
2007年 | 22502篇 |
2006年 | 21234篇 |
2005年 | 18685篇 |
2004年 | 15853篇 |
2003年 | 14107篇 |
2002年 | 11686篇 |
2001年 | 9847篇 |
2000年 | 8312篇 |
1999年 | 6812篇 |
1998年 | 5217篇 |
1997年 | 4554篇 |
1996年 | 4195篇 |
1995年 | 3639篇 |
1994年 | 3216篇 |
1993年 | 2407篇 |
1992年 | 2112篇 |
1991年 | 1547篇 |
1990年 | 1355篇 |
1989年 | 1207篇 |
1988年 | 923篇 |
1987年 | 646篇 |
1986年 | 479篇 |
1985年 | 399篇 |
1984年 | 375篇 |
1983年 | 267篇 |
1982年 | 249篇 |
1981年 | 181篇 |
1980年 | 160篇 |
1979年 | 149篇 |
1978年 | 64篇 |
1977年 | 74篇 |
1976年 | 56篇 |
1975年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The integration of computer theory and practice in higher vocational colleges is the necessary condition to realize the train-
ing of professional talents and improve the comprehensive quality of skilled talents. It is also the problem that needs to be solved
first in the teaching of computer major in higher vocational colleges. This paper firstly introduces the definition and connotation of
the integration of computer theory and practice, discusses on its construction objectives and basic concepts, then analyzes the con-
struction value of the integration of computer theory and practice, including the contents of employment, professional teaching, cur-
riculum supporting and qualification examination, finally discusses on the construction scheme of the training room of the integra-
tion of computer theory and practice, and gives the objective evaluation of the construction results, hoping to effectively improve the
level of the integration of computer theory and practice, and achieve the sustainable development of teaching. 相似文献
92.
伴随着互联网+的风生水起,信息量暴增的大数据时代应运而来,"网络原住民"大学生不可避免、理所当然地处于大数据洪流之中,但也为其个人隐私保护带来了极大挑战。文章针对大数据带来的安全隐私问题,指出大学生个人隐私泄露的可能原因,提出可以采取的个人隐私保护措施,给出大数据时代隐私保护几种技术,期望能给相关人士提供有效参考。 相似文献
93.
This article is concerned with the polynomial filtering problem for a class of nonlinear stochastic systems governed by the Itô differential equation. The system under investigation involves polynomial nonlinearities, unknown‐but‐bounded disturbances, and state‐ and disturbance‐dependent noises ((x,d)‐dependent noises for short). By expanding the polynomial nonlinear functions in Taylor series around the state estimate, a new polynomial filter design method is developed with hope to reduce the conservatism of the existing results. In virtue of stochastic analysis and inequality technique, sufficient conditions in terms of parameter‐dependent linear matrix inequalities (PDLMIs) are derived to guarantee that the estimation error system is input‐to‐state stable in probability. Moreover, the desired polynomial matrix can be obtained by solving the PDLMIs via the sum‐of‐squares approach. The effectiveness and applicability of the proposed method are illustrated by two numerical examples with one concerning the permanent magnet synchronous motor. 相似文献
94.
Many studies have demonstrated the strong relationships between physiological responses and driving stress, but they have done little to build a model that could be used to identify a driver's stress accurately in real time. The objective of this study is to develop a model that accurately classifies driving stress by monitoring physiological responses—specifically galvanic skin response (GSR). GSR data were collected from nine drivers with licenses obtained in the US in real road driving situations with two stress conditions—rest period (low stress) and highway or city driving (high stress). The validation drive was performed by one driver with licenses obtained in South Korea in real long‐term road driving situations with two stress conditions—rural area (low stress) and highway or highway under construction (high stress). Those two conditions were used to build a binary logistic regression model to classify low stress or high stress based on a driver's measured hand GSR. The overall classification accuracy of the developed model was found to be 85.3%, and the accuracy of cross validation, with a testing dataset, was found to be 83.2%. A simple logit model was developed to identify drivers' stress by incorporating their GSR data. The developed model can be embedded in a wearable device equipped with GSR sensors for drivers to detect their stress level in real time. 相似文献
95.
96.
Zhengwen Jiang 《Journal of Adhesion Science and Technology》2018,32(8):854-873
An analytical nonlinear solution was provided for unbalanced composite single-lap joint (CSLJ) using an improved one-dimensional beam model, which incorporated the effect of bending–tension coupling. The bending–tension coupling stiffness was introduced to characterize the coupling bending and tension behavior induced by the un-symmetric stacking sequence of composite laminates. The governing differential equations captured the bending–tension coupling behavior and the geometrically nonlinear features were constructed based on the displacement compatibility conditions of flexible interface. The transverse deformation in overlap region, edge moment factors and adhesive stress distributions for the unbalanced CSLJ with inflexible, intermediate flexibility and flexible adhesive can be determined by the present one-dimensional beam model. The accuracy of the present model was validated by the comparison with nonlinear finite element model. The effect of bending–tension coupling on edge moment factors and peak values of adhesive stresses was shed light on with the present model. 相似文献
97.
《工程(英文)》2020,6(7):812-826
Renewable energy sources (RESs) are considered to be reliable and green electric power generation sources. Photovoltaics (PVs) and wind turbines (WTs) are used to provide electricity in remote areas. Optimal sizing of hybrid RESs is a vital challenge in a stand-alone environment. The meta-heuristic algorithms proposed in the past are dependent on algorithm-specific parameters for achieving an optimal solution. This paper proposes a hybrid algorithm of Jaya and a teaching–learning-based optimization (TLBO) named the JLBO algorithm for the optimal unit sizing of a PV–WT–battery hybrid system to satisfy the consumer’s load at minimal total annual cost (TAC). The reliability of the system is considered by a maximum allowable loss of power supply probability (LPSPmax) concept. The results obtained from the JLBO algorithm are compared with the original Jaya, TLBO, and genetic algorithms. The JLBO results show superior performance in terms of TAC, and the PV–WT–battery hybrid system is found to be the most economical scenario. This system provides a cost-effective solution for all proposed LPSPmax values as compared with PV–battery and WT–battery systems. 相似文献
98.
Social media allow marketers to directly influence consumers through a diverse set of tools. The characteristics of individual platforms enable the development of creative and innovative strategies for social media marketing. This study aims at examining para-social interactions (PSI), their antecedents (i.e., attitude homophily and physical attractiveness), and their consequences (i.e., consumers’ sense of belonging, flow experience, urge to purchase, addiction, and impulse purchase). The mediating role of flow experience is also examined in this study. Findings, implications, and directions for further research are also presented in this study. 相似文献
99.
近年来,我市因雷击而导致搅拌站系统瘫痪停产、影响工程进度的事件时有发生,在针对混凝土搅拌站配料秤的实际检定工作中,也常发现配料秤的称重传感器因雷击损坏而影响计量准确性。因此,对混凝土搅拌站防雷的研究具有重要意义。本文阐述了雷电对混凝土搅拌站的主要危害,分析了混凝土搅拌站常见的雷击原因及其防护措施,旨在引起生产方、安装方以及使用方对混凝土搅拌站防雷的共同重视。 相似文献
100.
铁山头铜矿床处于铜陵矿集区的中东部,属于扬子陆块下扬子凹陷中的铜陵隆起。矿床位于凤凰山矿田北侧,成矿潜力较大。综合研究分析认为:①接触交代作用使得岩体接触带及附近变质形成矽卡岩矿化带;②区内凤凰山岩体(花岗闪长岩)系成矿母岩;③矿体主要赋存于花岗闪长岩与三叠系下统南陵湖组石灰岩接触带上;④矿床成因类型为高—中温热液交代矽卡岩型矿床。 相似文献