全文获取类型
收费全文 | 1297篇 |
免费 | 103篇 |
专业分类
电工技术 | 4篇 |
综合类 | 4篇 |
化学工业 | 332篇 |
金属工艺 | 4篇 |
机械仪表 | 18篇 |
建筑科学 | 57篇 |
矿业工程 | 4篇 |
能源动力 | 17篇 |
轻工业 | 171篇 |
水利工程 | 20篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 87篇 |
一般工业技术 | 182篇 |
冶金工业 | 345篇 |
原子能技术 | 1篇 |
自动化技术 | 151篇 |
出版年
2023年 | 15篇 |
2022年 | 56篇 |
2021年 | 73篇 |
2020年 | 28篇 |
2019年 | 35篇 |
2018年 | 37篇 |
2017年 | 31篇 |
2016年 | 56篇 |
2015年 | 42篇 |
2014年 | 55篇 |
2013年 | 67篇 |
2012年 | 66篇 |
2011年 | 111篇 |
2010年 | 92篇 |
2009年 | 74篇 |
2008年 | 70篇 |
2007年 | 84篇 |
2006年 | 48篇 |
2005年 | 52篇 |
2004年 | 50篇 |
2003年 | 27篇 |
2002年 | 26篇 |
2001年 | 20篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有1400条查询结果,搜索用时 15 毫秒
981.
The recent application of meta-analytic techniques to the topic of coronary proneness has proved useful in promoting a sound construct-validation approach, an approach that should have been used years ago. However, the meta-analytic methods and statistics themselves are subject to some degree of interpretation. This article explains and comments on some of the important conclusions and some key limitations that emerge from three recent meta-analyses of the Type A behavior pattern. Both methodological and conceptual issues are addressed. All in all, there is a remarkable degree of consensus about what we know and what we need to know. Strong evidence emerges that Type A behavior (assessed by the Structured Interview) is a significant risk factor for coronary heart disease, but the Type A construct still has not been adequately defined. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
982.
Modification of acoustic startle amplitude by a 10-ms tone prepulse (S1) was evaluated as a function of the interstimulus interval (ISI) between the onset of S1 and the onset of the startle-evoking stimulus (S2). Subjects were normal-hearing 1-month-old C57BL/6J (C57) mice and CBA/CaJ mice and 5-month-old C57 mice with high-frequency hearing loss. With a 2-ms ISI, 5-month-old C57 mice (but not the normal-hearing mice) exhibited pronounced prepulse augmentation (PPA) of startle: Amplitudes were much larger when S1 was present. Prepulse inhibition (PPI) occurred with ISls of 10–100 ms in all subject groups. With long ISls of 200 and 500 ms, however, PPI was strong only in 5-month-old C57 mice and only with S1 frequencies of 8, 12, and 16 kHz. Physiological studies of neural plasticity have shown that frequencies of 8–16 kHz become "over-represented" (more neurons responding) in the central auditory system of C57 mice, suggesting a link with prolonged PPI observed here. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
983.
Detecting the effects of latent depressive schemas constitutes an important step toward validating A. T. Beck's (1967) tenet of the depressive cognitive style as a causal factor in the onset and relapse of major depression. The authors examined whether a sample of formerly clinically depressed individuals continued to exhibit a negatively biased information-processing style in the absence of concurrent depressed mood. As predicted, the scores of formerly depressed individuals on 2 questionnaires tapping dysfunctional thinking did not differ from those of never depressed individuals, but responses of formerly depressed individuals were negatively biased on 2 of 3 information-processing measures administered following a self-focus manipulation. These results provide evidence for the persistence of a depressive schema in individuals who have recovered from major depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
984.
Cowen Emory L.; Spinell Arline; Wright Stephanie; Weissberg Roger P. 《Canadian Metallurgical Quarterly》1983,14(1):118
Reports survey findings based on the dissemination activities (1977–1981) of the Primary Mental Health Project, an innovative program model for early detection and prevention of school adjustment problems. Programs varied in professional and nonprofessional staffing patterns, screening procedures used, funding mechanisms, and day-to-day operating practices in ways that reflected districts' needs, populations served, and resources. The programs, however, shared 4 structural emphases: a focus on very young children, active early identification and screening, use of nonprofessional helpers to expand the reach of services, and development of new professional roles that catalyzed service delivery. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
985.
Cheng Der Yu Stephanie A. Sweetana Nancy I. Chu George J. L. Lee Ian J. Massey 《Drug development and industrial pharmacy》1989,15(4):609-620
RS-82856 is a new inotropic agent for treatment of congestive heart failure. Oral bioavailability was found to be very poor likely due to insufficient aqueous solubility (∼ 4.4 mcg/ml) and slow dissolution rate. Inclusion complexes with cyclodextrins were shown to enhance the solubility, dissolution rate and thereby oral bioavailability of the drug. Maximum solubilities of the drug complexes with alpha-, beta-, and gamma-cyclodextrin were 14, 30 and 55 times, respectively, more soluble than the uncomplexed drug. Phase solubility studies revealed a 1:l complexation constant of 136.5, 370.4, and 64.7 for alpha -, beta - and gamma-cyclodextrin complexes, respectively . The complexation between beta-cyclodextrin and the drug is apparently the strongest among the three cyclodextrins. Dissolution profiles of the beta-cyclodextrin complex indicated a dramatic increase in dissolution rate compared to that of the drug. However,a physical mixture of the beta-cyclodextrin and the drug gave an identical dissolution profile to that of the drug.The beta-cyclodextrin complex of the drug dissolves 90% with in 20 minutes while the free based is solves 25% with in the same time interval in water. In an acidic medium (ph 1.5) the beta-cyclodextrin complex and the free based is solve 90% and 30% respectively within 10 minutes.In asingle dose cross-over study in three dogs,the bioavailability of the beta-cyclodextrin complex was found to improve greatly over that of the drug. An increased Cmax (2.5 times),and an increased AUC (2.5 times) were observed with the beta-cyclodextrin complex compared to the drug. 相似文献
986.
Although attributional models of depression suggest that depression is associated with internal, stable, and global causal explanations of events, they do not specify whether the depressive attributional process involves the selection of certain causes, the assignment of dimensional meanings to those causes, or both. The extent of agreement between a priori and perceived dimensions of causes was examined in the present study, and the equivalence of the existing cause-rating method and 2 variants of the dimension-rating method were tested. 51 male and 45 female undergraduates were administered attribution and depression questionnaires. Findings indicate that the choice of causes did not reliably indicate the perceived dimensions and that there was poor convergence between existing methods that assess causes and those that assess dimensions. When causes and dimensions were each measured in a manner that avoided confounding by the other, each made a unique contribution to the prediction of depression scores. Cause ratings alone were significantly associated with depression scores, but the optimal prediction of depression included both causes and dimensions. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
987.
988.
Herdman Chris M.; LeFevre Jo-Anne; Greenham Stephanie L. 《Canadian Metallurgical Quarterly》1994,20(3):575
Ss named pseudohomophones (e.g., phocks) and nonpseudohomophones (e.g., snocks) under conditions in which words were or were not included in the stimulus lists. For Ss classified as fast responders, pseudohomophone advantages were not accompanied with base-word frequency effects. For slow responders, pseudohomophone naming was related to base-word frequency, but only when words were included in the stimulus lists. A dual-route model is proposed in which (1) lexical representations are frequency sensitive, (2) the relative use of nonlexical vs lexical information in phonological synthesis depends on strategic factors, and (3) overlapping lexical and nonlexical codes are assumed to lengthen processing time at the level of a phonological buffer. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
989.
Intimacy status in 48 men and 44 women (aged 21–35 yrs) was investigated in relation to ego-identity status in occupation, religion, politics, and sex role. All Ss were college educated, and most were employed in professional or skilled occupations. An intimacy status measure developed by J. L. Orlofsky et al (1973) was modified for use with adults and expanded by the addition of the merger status, describing relationships in which one partner dominated the other. There were no significant sex differences in intimacy or identity status; and as predicted by E. H. Erikson's (1963) theory, intimacy status was generally related to identity status. This relationship was not observed for occupational identity in either sex. It is suggested that Erikson's theory regarding the pattern of identity and intimacy resolutions may be extended from men to women, at least for the type of sample studied in the present investigation. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
990.