全文获取类型
收费全文 | 4303篇 |
免费 | 417篇 |
国内免费 | 138篇 |
专业分类
电工技术 | 274篇 |
综合类 | 244篇 |
化学工业 | 904篇 |
金属工艺 | 158篇 |
机械仪表 | 175篇 |
建筑科学 | 209篇 |
矿业工程 | 118篇 |
能源动力 | 116篇 |
轻工业 | 339篇 |
水利工程 | 62篇 |
石油天然气 | 119篇 |
武器工业 | 15篇 |
无线电 | 612篇 |
一般工业技术 | 640篇 |
冶金工业 | 268篇 |
原子能技术 | 57篇 |
自动化技术 | 548篇 |
出版年
2024年 | 21篇 |
2023年 | 68篇 |
2022年 | 137篇 |
2021年 | 164篇 |
2020年 | 116篇 |
2019年 | 80篇 |
2018年 | 106篇 |
2017年 | 108篇 |
2016年 | 148篇 |
2015年 | 180篇 |
2014年 | 198篇 |
2013年 | 268篇 |
2012年 | 247篇 |
2011年 | 273篇 |
2010年 | 241篇 |
2009年 | 210篇 |
2008年 | 270篇 |
2007年 | 223篇 |
2006年 | 243篇 |
2005年 | 162篇 |
2004年 | 149篇 |
2003年 | 141篇 |
2002年 | 158篇 |
2001年 | 138篇 |
2000年 | 105篇 |
1999年 | 99篇 |
1998年 | 93篇 |
1997年 | 94篇 |
1996年 | 69篇 |
1995年 | 56篇 |
1994年 | 37篇 |
1993年 | 32篇 |
1992年 | 26篇 |
1991年 | 36篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1976年 | 12篇 |
1975年 | 5篇 |
1970年 | 4篇 |
1965年 | 3篇 |
1964年 | 3篇 |
排序方式: 共有4858条查询结果,搜索用时 0 毫秒
101.
102.
Dodd Alyson L.; Mansell Warren; Morrison Anthony P.; Tai Sara 《Canadian Metallurgical Quarterly》2011,23(3):635
The Hypomanic Attitudes and Positive Predictions Inventory (HAPPI; W. Mansell, 2006) was developed to assess multiple, extreme, self-relevant appraisals of internal states. The present study aimed to validate the HAPPI in a clinical sample. Participants (N = 50) with a diagnosis of bipolar disorder (confirmed by a structured clinical interview) completed a series of questionnaires pertaining to clinical factors, reward motivation, cognitive style, symptoms, and functioning at baseline, in addition to the HAPPI. Over the following 4 weeks, participants were asked to complete self-report measures of symptoms (activation, perceived conflict, depression, and well-being), as well as work and social functioning, twice weekly. The authors hypothesized that the HAPPI would be associated with prospective bipolar symptoms and functioning, when controlling for baseline symptoms and potentially confounding measures. The HAPPI was positively, independently associated with activation and conflict after 4 weeks. Furthermore, individual HAPPI factors were associated with activation, conflict, and depression. The results provided preliminary support for the predictive validity of the HAPPI in a clinical sample. The HAPPI could be used in the future as a tool in cognitive behavioral therapy for bipolar disorder to identify problematic beliefs and guide formulation. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
103.
104.
Tai Sik Lee Dong Wook Lee Hyeeun Lee Hee Sun Park 《Canadian Metallurgical Quarterly》2005,21(4):159-163
The Leader–Member Exchange (LMX) relationship quality between superiors and subordinates in Korean civil engineering companies were empirically examined for superiors’ feedback-seeking behaviors. The results showed that for superiors, affect, loyalty, and contribution toward subordinates were positively related to seeking negative as well as positive feedback from subordinates. From subordinates’ point of view, affect, contribution, and professional respect toward their superiors were positively related to superiors’ negative feedback seeking, but affect was negatively related to superiors’ positive feedback seeking. It was also found that superiors and subordinates were not consensual in LMX and superiors’ feedback-seeking behaviors. For example, for superiors, all of the four LMX dimensions were positively related to superiors’ asking subordinates directly for feedback, whereas for subordinates, none of the LMX dimensions were significantly related to superiors’ asking subordinates directly for feedback. These and other findings are discussed in detail, and implications for the findings are provided. 相似文献
105.
随着国外技术的大量引进以及锅炉容量的增加,锅炉性能考核试验越来越多地要求采用ASME PTC4.1标准来对锅炉热效率进行计算,因此有必要对不同容量锅炉在GB10184-88标准和ASME PTC4.1标准下的锅炉效率结果进行比较、分析,以便对电厂的安全经济运行进行更好的指导。 相似文献
106.
利用Gleeble-3500热模拟试验机研究了低活化马氏体钢在变形温度为850~950 ℃、应变速率为0.001~1 s-1条件下的热变形行为。建立了流变应力本构方程,并评估了该方程的预测能力。绘制了低活化马氏体钢在不同应变下的热加工图。结果表明:在较高的应变速率条件下,该材料主要发生动态回复,在较高变形温度和较低应变速率下具有明显的动态再结晶特征;本构方程的预测结果与实验结果符合良好;变形温度870~930 ℃、应变速率0.001~0.01 s-1和变形温度920~950 ℃、应变速率0.3~1 s-1分别是真应变为0.4和0.6下最优的热加工区域。 相似文献
107.
Heng-Ming Tai 《Systems & Control Letters》1987,8(5):425-428
This paper addresses four characterizations of detectability and stabilizability for a broad class of linear continuous-time time-varying systems. It is shown that for the class of constant-rank systems all these notions of detectability and stabilizability are actually equivalent to each other. 相似文献
108.
采用真空感应熔炼制备了La0.8Mg0.2Ni3.3Co0.2Si x(x=0、0.1)电极合金,并将铸态合金进行真空退火处理,退火温度为900、950、1000和1050℃,保温时间为8h。用XRD分析了铸态及退火态合金的相结构,测试了铸态及退火态合金的电化学贮氢性能。结果表明,铸态及退火态合金均具有多相结构,包括两个主相(La,Mg)2Ni7和LaNi5以及一个残余相LaNi3。退火处理未改变合金的相组成,但使两个主相的含量发生明显改变。合金主相的晶格常数及晶胞体积随退火温度的增加而增加。铸态及退火态合金均具有良好的活化性能,第1次循环即可达到最大放电容量。退火处理明显改善了合金的电化学循环稳定性,合金的放电容量随退火温度的升高先增加后减小。合金的高倍率放电性能(HRD)、电化学交流阻抗谱(EIS)以及氢扩散系数(D)的测试表明,合金的电化学动力学随退火温度的升高先上升后降低。 相似文献
109.
Abstract This paper proposes a simple scheme to decompose an n×n nonpositive definite matrix, A, associated with simultaneous equations, A X = B, into a triple‐factors (lower triangular, diagonal, and upper triangular matrices), i.e., Å = L D U, without interchanging rows or columns of A, but with A expanded with new rows and new columns to an m×m matrix Å. Whenever a near‐zero diagonal element, say āii , is encountered and used as a pivoting element, an appropriate positive real number, say p, is added to this diagonal element, and a new term —pxk is also added to the i‐th equation, where xk is a new variable called “dummy variable'’. If we also add a new equation —pxi + pxk = 0 to enforce the new added variable xk equal to xi then the modified i‐th equation has the same effect as the original equation. Therefore, the original solution X can be found directly from the expanded solution of the modified expanded equation. The method is very useful in solving the following problems: (1) nonlinear problems near the limit state, (2) postbuckling analysis, (3) system equations with constraint conditions, and (4) getting eigenvectors from eigenvalues. 相似文献
110.