全文获取类型
收费全文 | 4615篇 |
免费 | 292篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 23篇 |
综合类 | 6篇 |
化学工业 | 1587篇 |
金属工艺 | 29篇 |
机械仪表 | 76篇 |
建筑科学 | 185篇 |
矿业工程 | 5篇 |
能源动力 | 92篇 |
轻工业 | 856篇 |
水利工程 | 44篇 |
石油天然气 | 16篇 |
无线电 | 218篇 |
一般工业技术 | 555篇 |
冶金工业 | 720篇 |
原子能技术 | 30篇 |
自动化技术 | 472篇 |
出版年
2024年 | 10篇 |
2023年 | 66篇 |
2022年 | 347篇 |
2021年 | 343篇 |
2020年 | 159篇 |
2019年 | 152篇 |
2018年 | 151篇 |
2017年 | 146篇 |
2016年 | 151篇 |
2015年 | 157篇 |
2014年 | 191篇 |
2013年 | 292篇 |
2012年 | 259篇 |
2011年 | 332篇 |
2010年 | 243篇 |
2009年 | 240篇 |
2008年 | 240篇 |
2007年 | 221篇 |
2006年 | 159篇 |
2005年 | 128篇 |
2004年 | 131篇 |
2003年 | 113篇 |
2002年 | 98篇 |
2001年 | 38篇 |
2000年 | 52篇 |
1999年 | 47篇 |
1998年 | 48篇 |
1997年 | 34篇 |
1996年 | 38篇 |
1995年 | 32篇 |
1994年 | 35篇 |
1993年 | 29篇 |
1992年 | 20篇 |
1991年 | 9篇 |
1990年 | 19篇 |
1989年 | 20篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1973年 | 4篇 |
1965年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有4914条查询结果,搜索用时 15 毫秒
71.
In the past few years, the project management (PM) profession has grown exponentially. Yet recent studies in the information technology (IT) sector have found that the use of PM methodologies alone does not guarantee project success. In fact, IT project success is seen to rely on the ability of project managers to be agents of change (i.e., individuals who lead organizational change efforts), a traditional role of practitioners of organization development and change. This article identifies the knowledge, skills, and competencies that are common to organization development (OD) practitioners and project managers, as represented by 6 principles or competencies that OD and PM change methods snare: communication, teamwork, process management, leadership, training, and continuous learning. The importance of these 6 principles in developing professional project managers as effective agents of change is explored with the intent of finding means to improve upon current IT project success rates. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
72.
The discovery of conjunctive causes--factors that act in concert to produce or prevent an effect--has been explained by purely covariational theories. Such theories assume that concomitant variations in observable events directly license causal inferences, without postulating the existence of unobservable causal relations. This article discusses problems with these theories, proposes a causal-power theory that overcomes the problems, and reports empirical evidence favoring the new theory. Unlike earlier models, the new theory derives (a) the conditions under which covariation implies conjunctive causation and (b) functions relating observable events to unobservable conjunctive causal strength. This psychological theory, which concerns simple cases involving 2 binary candidate causes and a binary effect, raises questions about normative statistics for testing causal hypotheses regarding categorical data resulting from discrete variables. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
73.
Berger Seymour M.; Hampton Katherine L.; Carli Linda L.; Grandmaison Paul S.; Sadow Janice S.; Donath Clifford H.; Herschlag Laura R. 《Canadian Metallurgical Quarterly》1981,40(3):479
Three experiments with 204 undergraduates examined the hypothesis that an audience can inhibit overt practice and thereby impair learning of unfamiliar words and enhance learning of familiar words. This hypothesis was derived from an analysis of motoric and symbolic mediation during learning. In comparison with learning while alone, the results show that the audience inhibited overt practice of unfamiliar and familiar words and that reduced practice was detrimental to learning unfamiliar words. Inhibition of overt practice with an audience enhanced learning of familiar words in only 1 of the experiments. Instructions to practice overtly reduced the audience-inhibition effect in learning unfamiliar words. The studies are discussed in the context of drive-theory explanations for social facilitation effects in learning. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
Lewis Melissa A.; Hove M. Christina; Whiteside Ursula; Lee Christine M.; Kirkeby Benjamin S.; Oster-Aaland Laura; Neighbors Clayton; Larimer Mary E. 《Canadian Metallurgical Quarterly》2008,22(1):58
The present research was conducted to clarify the relationships among social anxiety, alcohol consumption, alcohol-related problems, and negative-reinforcement drinking motives among college students. Heavy drinking students (N = 316, 53.80% female) completed self-report measures of social anxiety, alcohol consumption, alcohol-related problems, and drinking motives. Findings indicated that students higher in social anxiety consumed less alcohol but experienced more negative consequences. Moreover, the relationship between social anxiety and negative consequences was mediated by coping and conformity drinking motives in addition to alcohol consumption. In the context of social anxiety, the current research demonstrates the importance of examining problematic drinking as distinct constructs: alcohol consumption and negative consequences. Findings are also discussed in terms of implications for interventions with socially anxious students. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
75.
Smith Laura; Constantine Madonna G.; Graham Sheila V.; Dize Chelsea B. 《Canadian Metallurgical Quarterly》2008,39(3):337
Multicultural competence has become a mainstay within the training of professional psychologists, yet important areas within this framework remain to be more fully addressed. In particular, the dynamics of contemporary forms of racism have largely gone unexplored, depriving psychologists of clear direction in exploring the deepest levels of racist influences in their work. This qualitative analysis sought to shed light into this area by studying White people's experiences of race and racism. Although most affirmed the existence of racism, it was "spun" by most White participants--in other words, interpreted to their own advantage-into a problem that lies outside the scope of their own lives and responsibilities. Implications and resources for the practice and training of professional psychologists are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
85 7–12 yr olds were asked to discuss happy, sad, or affectively neutral incidents that had been experienced either by themselves or by another child. Following the inducement of affect, the Ss were given the opportunity to share their experimental earnings with some less fortunate children. As predicted, a significant interaction of the discussion topic (self/other) and affect was found. Ss relating sad experiences encountered by another individual shared significantly more than those describing sad incidents that they had experienced. Although older Ss were more generous than the younger Ss in sharing their experimental earnings, age did not interact with the other experimental variables. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
Yilin Han Marianne King Evgenii Tikhomirov Povilas Barasa Cleide Dos Santos Souza Jonas Lindh Daiva Baltriukiene Laura Ferraiuolo Mimoun Azzouz Maurizio R. Gullo Elena N. Kozlova 《International journal of molecular sciences》2022,23(10)
Three-dimensional (3D) cultures, so-called organoids, have emerged as an attractive tool for disease modeling and therapeutic innovations. Here, we aim to determine if boundary cap neural crest stem cells (BC) can survive and differentiate in gelatin-based 3D bioprinted bioink scaffolds in order to establish an enabling technology for the fabrication of spinal cord organoids on a chip. BC previously demonstrated the ability to support survival and differentiation of co-implanted or co-cultured cells and supported motor neuron survival in excitotoxically challenged spinal cord slice cultures. We tested different combinations of bioink and cross-linked material, analyzed the survival of BC on the surface and inside the scaffolds, and then tested if human iPSC-derived neural cells (motor neuron precursors and astrocytes) can be printed with the same protocol, which was developed for BC. We showed that this protocol is applicable for human cells. Neural differentiation was more prominent in the peripheral compared to central parts of the printed construct, presumably because of easier access to differentiation-promoting factors in the medium. These findings show that the gelatin-based and enzymatically cross-linked hydrogel is a suitable bioink for building a multicellular, bioprinted spinal cord organoid, but that further measures are still required to achieve uniform neural differentiation. 相似文献
78.
Laura Mannarino Lara Paracchini Federica Pezzuto Gheorghe Emilian Olteanu Laura Moracci Luca Vedovelli Irene De Simone Cristina Bosetti Monica Lupi Rosy Amodeo Alessia Inglesi Maurizio Callari Serena Penpa Roberta Libener Sara Delfanti Antonina De Angelis Alberto Muzio Paolo Andrea Zucali Paola Allavena Giovanni Luca Ceresoli Sergio Marchini Fiorella Calabrese Maurizio DIncalci Federica Grosso 《International journal of molecular sciences》2022,23(10)
79.
Christabelle Rajesh Satish Sagar Ashok Kumar Rathinavel Divya Thomas Chemparathy Xianlu Laura Peng Jen Jen Yeh Michael A. Hollingsworth Prakash Radhakrishnan 《International journal of molecular sciences》2022,23(10)
Elevated levels of Mucin-16 (MUC16) in conjunction with a high expression of truncated O-glycans is implicated in playing crucial roles in the malignancy of pancreatic ductal adenocarcinoma (PDAC). However, the mechanisms by which such aberrant glycoforms present on MUC16 itself promote an increased disease burden in PDAC are yet to be elucidated. This study demonstrates that the CRISPR/Cas9-mediated genetic deletion of MUC16 in PDAC cells decreases tumor cell migration. We found that MUC16 enhances tumor malignancy by activating the integrin-linked kinase and focal adhesion kinase (ILK/FAK)-signaling axis. These findings are especially noteworthy in truncated O-glycan (Tn and STn antigen)-expressing PDAC cells. Activation of these oncogenic-signaling pathways resulted in part from interactions between MUC16 and integrin complexes (α4β1), which showed a stronger association with aberrant glycoforms of MUC16. Using a monoclonal antibody to functionally hinder MUC16 significantly reduced the migratory cascades in our model. Together, these findings suggest that truncated O-glycan containing MUC16 exacerbates malignancy in PDAC by activating FAK signaling through specific interactions with α4 and β1 integrin complexes on cancer cell membranes. Targeting these aberrant glycoforms of MUC16 can aid in the development of a novel platform to study and treat metastatic pancreatic cancer. 相似文献
80.
Ornella Rondinone Alessio Murgia Jole Costanza Silvia Tabano Margherita Camanni Luigi Corsaro Laura Fontana Patrizia Colapietro Luciano Calzari Silvia Motta Carlo Santaniello Tatjana Radaelli Enrico Ferrazzi Silvano Bosari Davide Gentilini Silvia Maria Sirchia Monica Miozzo 《International journal of molecular sciences》2022,23(10)