全文获取类型
收费全文 | 1567篇 |
免费 | 67篇 |
国内免费 | 1篇 |
专业分类
1635篇 |
出版年
2023年 | 11篇 |
2020年 | 11篇 |
2019年 | 32篇 |
2018年 | 34篇 |
2017年 | 45篇 |
2016年 | 40篇 |
2015年 | 28篇 |
2014年 | 26篇 |
2013年 | 191篇 |
2012年 | 57篇 |
2011年 | 63篇 |
2010年 | 31篇 |
2009年 | 30篇 |
2008年 | 42篇 |
2007年 | 68篇 |
2006年 | 53篇 |
2005年 | 30篇 |
2004年 | 27篇 |
2003年 | 37篇 |
2002年 | 38篇 |
2001年 | 54篇 |
2000年 | 53篇 |
1999年 | 49篇 |
1998年 | 22篇 |
1997年 | 13篇 |
1995年 | 15篇 |
1993年 | 14篇 |
1992年 | 18篇 |
1991年 | 28篇 |
1990年 | 32篇 |
1989年 | 23篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 21篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1980年 | 13篇 |
1978年 | 19篇 |
1977年 | 10篇 |
1976年 | 17篇 |
1975年 | 18篇 |
1974年 | 14篇 |
1973年 | 18篇 |
1972年 | 14篇 |
1970年 | 20篇 |
1969年 | 16篇 |
1968年 | 19篇 |
1967年 | 15篇 |
排序方式: 共有1635条查询结果,搜索用时 0 毫秒
81.
By atomic-scale high-angle annular dark-field scanning transmission electron microscopy, the long-period stacking ordered (LPSO) structures in a near-equilibrium Mg97Zn1Y2 (at.%) alloy have been characterised. In addition to 18R and 14H, new polytypes of LPSO structures are analysed and determined as 60R, 78R, 26H, 96R, 38H, 40H, 108H and 246R. All of these LPSO structures feature AB′C′A building blocks with two Mg layers and three Mg layers sandwiched between them. The Bravais lattices and space groups of new polytypes of LPSO structures were easily determined via the newly introduced method. A structural relationship between the LPSOs is proposed. 相似文献
82.
Hamilton JW 《Psychoanalytic review》2002,89(6):889-909
83.
84.
Z. Harakeh R. Engels E. Den Exter Blokland R. Scholte A. Vermulst 《Psychology & health》2013,28(7):823-841
This longitudinal study examined the reciprocal effects of the frequency of parent–adolescent communication on tobacco-related issues (smoking-specific communication), and adolescents’ smoking. Participants were 428 Dutch older and younger siblings between 13 and 16 years old. Smoking-specific communication did not affect youth smoking in general; however, among younger, but not older, siblings, smoking-specific communication was associated with a higher likelihood of smoking over time. In addition, when adolescents already smoked parents started to talk more frequently about smoking-related issues with their older and younger adolescents later on. Neither the quality of smoking-specific communication, the quality of parent–adolescent relationship, nor parental smoking moderated these reciprocal effects. In conclusion, prevention campaigns encouraging parents to undertake smoking-specific communication might not be desirable. 相似文献
85.
Z. Piotrowski 《Journal of personality assessment》2013,95(4):172-175
Abstract This is a supplement to the Rorschach bibliographies published by Dr. P. E. Vernon; the last of these was published in the January 1937 issue of the Rorachach Research Exchange. All available articles which are not contained in Dr. Vernon's bibliography are included. Those articles which have appeared in the Rorschach Research Exchange but which have not appeared elsewhere are omitted. 相似文献
86.
Y. Wang S.L. Shang H. Zhang L.-Q. Chen Z.-K. Liu 《Philosophical Magazine Letters》2013,93(12):851-859
To understand the Invar anomalies, such as negative thermal expansion and spontaneous magnetization, we have applied our recently developed thermodynamic framework for a system with itinerant-electron magnetism to the ordered Fe3Pt. The framework has coherently predicted the finite temperature intermixing between the fully ferromagnetic (FM) configuration and the spin-flipping configurations (SFCs). We have also discovered a tri-critical point at which a high-temperature second-order phase transition, between the fully ordered FM phase and the paramagnetic phase which is disordered due to SFCs, becomes first order at low temperatures. 相似文献
87.
Magnesium oxide (MgO) films and particles have been collected by pressurised filtration of a Mg-8.6wt%Al-0.67wt%Zn (AZ91D) alloy melt. The morphology of the oxides and their interfaces with the α-Mg phase were investigated by high-resolution transmission electron microscopy. It was found that the oxide films consisted of large numbers of sub-micrometre-sized MgO particles, and that melt shearing can effectively break up the oxide films and disperse the oxide particles. For the first time, orientation relationships (ORs) of OR I: [1?1?1]MgO~2° from (0?0?0?1)α-Mg and (0?1?1)MgO?//[2?1?1?0)α-Mg; and OR II: (1?1?1)MgO//(1?1?0?1)α-Mg and [0?1?1]MgO//[1?2?1?1]α-Mg, were observed between the MgO particles and the α-Mg matrix. The calculated Bramfitt planar disregistries were 5.5% and 2.5% for the two ORs, respectively, indicating good lattice matching between MgO and α-Mg at the interface. With the evidence of grain refinement effect observed in the sheared AZ91D magnesium alloy, the possibility of MgO particles to act as potent nucleants for heterogeneous nucleation of α-Mg grains is discussed in terms of the crystallographic criterion. 相似文献
88.
The present studies examined the nature of visuo-spatial working memory development using conventional visual span and spatial span measures. Children aged between 6 and 13 years and adults aged 18-38 years were employed as participants. In Study 1, visual span, spatial span, articulation rate, and verbal fluency competencies were measured. In Study 2, visual span and spatial span maintenance was subject to five interference formats: nil, speech articulation, verbal fluency, visual masking, and spatial tapping. Distinct developmental rates were found for the two span tasks, which in the older children were correlated with the verbal fluency measure. Study 2 provided experimental evidence of the contribution of executive and spatial processes to spatial and to visual span maintenance. The results are interpreted as indicating that these memory span procedures make complex demands upon the visuo-spatial working memory architecture and consequently a precise identification of the process that actually develop is compromised. It is suggested that a componential approach where tasks are constructed to tap specific working memory components would afford a more accurate understanding of the development of these processes. 相似文献
89.
Kathleen B. McDermott Jeffrey G. Ojemann Steven E. Petersen John M. Ollinger Abraham Z. Snyder Erbil Akbudak 《Memory (Hove, England)》2013,21(5-6):661-680
Functional magnetic resonance imaging (fMRI) was used to compare directly episodic encoding and retrieval. During encoding, subjects studied visually presented words and reported via keypress whether each word represented a pleasant or unpleasant concept (intentional, deep encoding). During the retrieval phase, subjects indicated (via keypress) whether visually presented words had previously been studied. No reliable differences were found during the recognition phase for words that had been previously studied and those that had not been studied. Areas preferentially active during encoding (relative to retrieval) included left superior frontal cortex, medial frontal cortex, left superior temporal cortex, posterior cingulate, left parahippocampal gyrus, and left inferior frontal gyrus. Regions more active in retrieval than encoding included bilateral inferior parietal cortex, bilateral precuneus, right frontal polar cortex, right dorsolateral prefrontal cortex, and right inferior frontal/insular cortex. 相似文献
90.
Daniel Z. Korman 《Philosophical Studies》2010,149(3):387-393
Kripke maintains that one who stipulatively introduces the term ‘one meter’ as a rigid designator for the length of a certain
stick s at time t is in a position to know a priori that if s exists at t then the length of s at t is one meter. Some (e.g.,
Soames 2003) have objected to this alleged instance of the contingent a priori on the grounds that the stipulator's knowledge
would have to be based in part on substantive metalinguistic knowledge. I examine Soames's argument for the a posteriority
of the relevant metalinguistic knowledge, and I argue that its main premise is false. 相似文献