全文获取类型
收费全文 | 4577篇 |
免费 | 451篇 |
国内免费 | 230篇 |
专业分类
电工技术 | 1048篇 |
综合类 | 720篇 |
化学工业 | 353篇 |
金属工艺 | 136篇 |
机械仪表 | 239篇 |
建筑科学 | 152篇 |
矿业工程 | 187篇 |
能源动力 | 97篇 |
轻工业 | 228篇 |
水利工程 | 42篇 |
石油天然气 | 122篇 |
武器工业 | 18篇 |
无线电 | 250篇 |
一般工业技术 | 272篇 |
冶金工业 | 644篇 |
原子能技术 | 37篇 |
自动化技术 | 713篇 |
出版年
2024年 | 17篇 |
2023年 | 41篇 |
2022年 | 85篇 |
2021年 | 102篇 |
2020年 | 103篇 |
2019年 | 104篇 |
2018年 | 91篇 |
2017年 | 111篇 |
2016年 | 126篇 |
2015年 | 161篇 |
2014年 | 254篇 |
2013年 | 269篇 |
2012年 | 298篇 |
2011年 | 370篇 |
2010年 | 294篇 |
2009年 | 292篇 |
2008年 | 284篇 |
2007年 | 289篇 |
2006年 | 267篇 |
2005年 | 272篇 |
2004年 | 242篇 |
2003年 | 240篇 |
2002年 | 176篇 |
2001年 | 150篇 |
2000年 | 123篇 |
1999年 | 82篇 |
1998年 | 55篇 |
1997年 | 54篇 |
1996年 | 59篇 |
1995年 | 49篇 |
1994年 | 45篇 |
1993年 | 24篇 |
1992年 | 25篇 |
1991年 | 16篇 |
1990年 | 14篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1977年 | 3篇 |
1965年 | 3篇 |
1964年 | 4篇 |
1963年 | 3篇 |
1958年 | 2篇 |
1957年 | 2篇 |
1956年 | 3篇 |
1955年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有5258条查询结果,搜索用时 31 毫秒
1.
2.
Does life satisfaction moderate the effects of stressful life events on psychopathological behavior during adolescence? 总被引:1,自引:0,他引:1
Psychologists within a positive psychology framework have proposed the existence of a set of psychological strengths that buffer against the development of psychopathology. To date, most research efforts in positive psychology have focused on adults. This longitudinal study tested the prediction that adolescents' judgments of life satisfaction moderate the influence of stressful life events on the subsequent development of psychopathological behavior. Using a sample of 816 middle and high school students, the study demonstrated support for the moderational model for externalizing behavior outcomes, but not internalizing behavior problems. Specifically, adolescents with positive life satisfaction (vs. those who were dissatisfied with their lives) were less likely to develop later externalizing behaviors in the face of stressful life events. The study also revealed that adolescent life satisfaction reports show moderate stability across a one-year time frame and independently predict subsequent externalizing behavior even while controlling for prior levels of externalizing behavior... (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
3.
4.
Robben J.; der Schueren J.Van; Verhasselt P.; Aert R.; Volckaert G. 《Protein engineering, design & selection : PEDS》1995,8(2):159-165
The deletion of nine residues from the C-terminus of the bacterialchloramphenicol acetyltransferase (CAT) results in depositionof the mutant protein in cytoplasmic inclusion bodies and lossof chloramphenicol resistance in Escherichia coli. This foldingdefect is relieved by C-terminal fusion of the polypeptide withas few as two residues. Based on these observations, efficientpositive selection for the cloning of DNA fragments has beendemonstrated. The cloning vector encodes a C-terminally truncatedCAT protein. Restriction sites in front of the stop codon allowthe insertion of target DNA, resulting in the production ofproperly folded CAT fusion proteins and regained chloramphenicolresistance. The positive selection of recombinants is accomplishedby growth of transformants on chloramphenicol-containing agarplates. The method appears particularly convenient for the cloningof DNA fragments amplified by the PCR because minimal informationto restore CAT folding can be included in the primers. The cloningof random sequences shows that the folding defect can be relievedby fusion to a wide variety of peptides, providing great flexibilityto the positive selection system. This vector may also contributeto the determination of the role of the C-terminus in CAT folding. 相似文献
5.
This paper presents a method to compensate voltage sags with minimum energy injection for a series‐connected voltage restorer using a micro‐SMES. A circuit for extracting the fundamental symmetrical components from sag voltages and a minimum energy injection algorithm is described. Simulations of voltage sag compensation have been carried out using PSCAD/EMTDC for various faults. The simulation results confirm the validity of the proposed method and show the possibility of reducing the size of energy storage devices. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 70–80, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10047 相似文献
6.
温克勤 《徐州建筑职业技术学院学报》2005,5(1):1-6
对儒家伦理的基本价值与基本特点以及局限性进行了疏理和分析,对于国内外学者对儒家伦理的肯定性评价和提出的有关儒学研究的理论方法作出了评介,在此基础上提出了研究儒家伦理的几点认识和启示. 相似文献
7.
Penedo Frank J.; Dahn Jason R.; Gonzalez Jeffrey S.; Molton Ivan; Carver Charles S.; Antoni Michael H.; Roos Bernard A.; Schneiderman Neil 《Canadian Metallurgical Quarterly》2003,22(2):220
This study evaluated relations among optimism, perceived stress management skills (PSMS), and positive mood in 46 men who had surgical treatment for localized prostate cancer. The authors found that optimism, PSMS, and positive mood scores were positively correlated. Positive mood was unrelated to demographic and disease-related control variables. In a hierarchical regression model controlling for PSMS, the relationship between optimism and positive mood became nonsignificant, whereas PSMS remained a correlate of positive mood. Results suggest that the relationship between optimism and positive mood may be mediated by belief in being able to use stress management techniques effectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
Some therapists hold that the Bobo and other aggressive toys should be excluded from the playroom as they elicit acting-out behavior that is transferred to the world outside the playroom. However, many therapists view the inclusion of these items as imperative elements that facilitate positive growth and maturation in the child. Interviews with authorities in the field of play therapy support the position that the inclusion of the Bobo is not only useful, but a therapeutic necessity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Lash Steven J.; Stephens Robert S.; Burden Jennifer L.; Grambow Steven C.; DeMarce Josephine M.; Jones Mark E.; Lozano Brian E.; Jeffreys Amy S.; Fearer Stephanie A.; Horner Ronnie D. 《Canadian Metallurgical Quarterly》2007,21(3):387
Although continuing care is strongly related to positive treatment outcomes for substance use disorder (SUD), participation rates are low and few effective interventions are available. In a randomized clinical trial with 150 participants (97% men), 75 graduates of a residential Veterans Affairs Medical Center SUD program who received an aftercare contract, attendance prompts, and reinforcers (CPR) were compared to 75 graduates who received standard treatment (STX). Among CPR participants, 55% completed at least 3 months of aftercare, compared to 36% in STX. Similarly, CPR participants remained in treatment longer than those in STX (5.5 vs. 4.4 months). Additionally, CPR participants were more likely to be abstinent compared to STX (57% vs. 37%) after 1 year. The CPR intervention offers a practical means to improve adherence among individuals in SUD treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
In this paper we have studied the control of linear systems with algebraic-equation constraint. A pole-assignment controller with two-layer structure for such constrained systems has been presented. The objective of the controller is to assign the desired poles to constrained system and simultaneously force the corresponding closed-loop system to satisfy the constraint. The conditions for the existence of pole-assignment controller are discussed in different cases. The implementation algorithm of pole-assignment controller is also presented. An example is given to illustrate the validity of the method in this paper. 相似文献