全文获取类型
收费全文 | 1857篇 |
免费 | 48篇 |
出版年
2019年 | 29篇 |
2018年 | 37篇 |
2017年 | 33篇 |
2016年 | 40篇 |
2015年 | 22篇 |
2014年 | 42篇 |
2013年 | 227篇 |
2012年 | 73篇 |
2011年 | 65篇 |
2010年 | 41篇 |
2009年 | 35篇 |
2008年 | 54篇 |
2007年 | 61篇 |
2006年 | 55篇 |
2005年 | 49篇 |
2004年 | 41篇 |
2003年 | 47篇 |
2002年 | 47篇 |
2001年 | 64篇 |
2000年 | 64篇 |
1999年 | 55篇 |
1998年 | 28篇 |
1997年 | 21篇 |
1995年 | 18篇 |
1993年 | 19篇 |
1992年 | 18篇 |
1991年 | 32篇 |
1990年 | 34篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 21篇 |
1986年 | 27篇 |
1985年 | 24篇 |
1984年 | 13篇 |
1983年 | 22篇 |
1982年 | 21篇 |
1980年 | 13篇 |
1979年 | 20篇 |
1978年 | 19篇 |
1977年 | 13篇 |
1976年 | 23篇 |
1975年 | 20篇 |
1974年 | 21篇 |
1973年 | 25篇 |
1972年 | 15篇 |
1970年 | 19篇 |
1969年 | 14篇 |
1968年 | 19篇 |
1967年 | 15篇 |
1966年 | 12篇 |
排序方式: 共有1905条查询结果,搜索用时 62 毫秒
891.
Transformation and misfit dislocations are used to describe the motion of glissile interfaces with one set of misfit dislocations in the framework of the Frank?Bilby equation. The sweep of these glissile interfaces brings about an invariant-plane-strain type shape deformation. Our approach explains the glissile motion of martensitic interfaces and small-angle symmetrical tilt grain boundaries. It is consistent with the phenomenological theory of martensite crystallography but more flexible. 相似文献
892.
The roughening kinetics of Ti1? x Al x N (0?x? 1) films 600 nm thick synthesized by reactive dc magnetron sputtering on Si(100) substrates has been investigated by atomic force microscopy (AFM). The quantification of surface roughening was achieved by calculation of both vertical root-mean-square roughness and lateral correlation lengths of the film surface using the height-height correction functions of measured AFM images. For all the Ti1? x Al x N films, a steady roughness exponent α = 0.94 ± 0.03 was determined. The evolution of the surface topography as a function of Al concentration is discussed in terms of the competition between surface diffusion and shadowing instability during sputter deposition. 相似文献
893.
The superheating behaviour of embedded particles induced by semicoherent interfaces has been observed in many circumstances. In this paper, a phenomeno‐ logical model for melt nucleation on misfit dislocations at a semicoherent interface is proposed. A kinetic limit for semicoherent-interface-induced superheating, which is in good agreement with the results of experiments and computer simulations, is derived from this model. Calculations and analyses based on the model reveal that melting prefers to initiate at the semicoherent interface and that superheating of embedded particles is possible for a melt nucleation contact angle less than 90°. Among the matrix-dependent parameters, the contact angle and the shear modulus of the matrix are found to be dominant in determining the superheating of embedded particles. 相似文献
894.
J. C. Jiang † E. I. Meletis C. L. Chen Y. Lin Z. Zhang W. K. Chu 《Philosophical Magazine Letters》2013,93(7):443-450
We report the detailed microstructural study of a CaCu3Ti4O12 (CCTO) thin film using transmission electron microscopy (TEM). The CCTO thin film studied in this work was deposited on a (001)-oriented LaAlO3 (LAO) substrate by pulsed-laser ablation and has a high dielectric constant of about 104 at 1?MHz at room temperature; however, the mechanism for such a dielectric property is not yet understood. Plan-view TEM studies show that the CCTO samples have orthogonal domain structures with the edge nearly parallel to either the [100] or the [010] direction of the CCTO. A minor anatase TiO2 phase was found at the domain boundaries. The CCTO and the TiO2 phases are separated by an amorphous-like layer that has a thickness of several nanometres. Cross-sectional TEM studies reveal that both CCTO and TiO2 in the films are c axis oriented with a very sharp interface to the LAO-(001) substrate and possess a unique crystallographic orientation relationship of (001) CCTO //(001)TiO 2 //(001) LAO and [100] CCTO //[100] TiO 2 //[100] LAO. The Rutherford back-scattering ion chanelling studies suggest a composition of Ca1.5Cu3Ti5.5O16 for the film, in which the extra calcium, titanium and oxygen form the anatase TiO2 phase and amorphous calcium oxide layer that separates the CCTO and TiO2 phases. Such nanocomposite-like structures may provide an important clue to the mechanism of the dielectric property of these films. 相似文献
895.
Anna Abraham 《创造力研究杂志》2013,25(1):19-24
Abstract Vandervert, Schimpf, and Liu (this issue) have presented a cerebellar model of creativity in the featured article by relating their ideas to processes of working memory in relation to the cerebellum as well as by generalizing the motor control role of the cerebellum to extend to non-motor facets of cognition. In the present article, I discuss the weaknesses of their approach at different levels, ranging from the inadequate definition of the construct under study and the lack of specificity in their claims, to the counterintuitive underlying rationale of their approach, and the inadequate evidence provided to cement their ideas. I end by briefly outlining what would be necessary to propound an account of creativity that is uniquely attributable to cerebellum function. 相似文献
896.
The Creativity Quotient (CQ) is a novel metric building on ideational fluency that accounts for both the number of novel ideas (ideation) and the number of distinct categories (fluency) these ideas fall into. Categories are, however, difficult to define unambiguously and objectively. We propose that the principal contribution of this article is an entirely algorithmic approach based on concept networks, and an information metric defined thereon. It requires only measures of the similarity between concepts, which may come from databases such as Wordnet, Wikipedia, Google, or corpus analysis tools. In the special case of strong, unique categories it reduces directly to CQ. 相似文献
897.
Ehud Z. Benor 《Religion》2013,43(1):59-66
Maimonides’ statements on prayer pose considerable challenges to interpreters who seek to find his work a unified and coherent philosophy of religion. It is especially difficult to see how his advocacy of a silent meditation that follows intellectual comprehension of divine matters can be harmonized with his thoroughly ritualized approach to the daily supplicatory prayer of Jewish liturgy. Yet, it is the purpose of the following pages to outline an interpretation of Maimonides’ philosophy of religion according to which supplicatory prayer and intellectual meditation are not disparate spiritual phenomena, but complementary dimensions of a distinctive form of ethical‐intellectual worship. 相似文献
898.
Hospitalized psychiatric patients responding on the Bender-Gestalt Test with the ‘penetration’ of Design 6 into Design 5, did display significantly more suicidal ideation in the predicted direction than did a matched control group (P < .005). The results were taken to suggest the utility of combining this variable with other predictive criteria derived from Rorschach research to help the clinician make recommendations about suicidally ideated psychiatric patients. 相似文献
899.
S. Z. Dudek 《Journal of personality assessment》2013,95(2):127-137
Two therapy groups were followed by means of repeated interaction testing over the course of their therapeutic lifetime. The consensus Rorschach, analyzed as if it were the product of a single individual, indicated marked differences in the progress of the two groups with evidence of growth, expansion in the case of one group and a therapeutic stalemate in the case of the second group. Independent clinical evaluation of therapeutic progress by the therapists of both groups were in complete agreement with the consensus Rorschach psychograms. The possibility that non-conformist members may contribute to poor therapeutic progress is considered. 相似文献
900.
This article conceptually links theory and research on volunteerism to different forms of political activity, specifically activism and civic engagement. Multiple perspectives and measures of personality as antecedents of volunteerism, activism, and civic engagement are outlined, including individual differences in motivations, interpersonal orientations, and traits. Next, self-report data from 624 people involved in AIDS service organizations (as clients, volunteers, staff, or supporters) are utilized to empirically explore the best personality predictors of AIDS activism and civic engagement. Other-focused rather than self-focused motivation better predicted AIDS activism and civic engagement. The only measure of interpersonal orientation consistently related to these outcomes was communal orientation; as well, only the trait of extraversion was related to both outcomes. In analyses testing the predictive power of constellations of personality measures, other-focused motivation better predicted AIDS activism and civic engagement than the other measures of motivation, interpersonal orientation, and traits. Finally, meditational analyses supported a developmental sequence in which other-focused motivation leads to specific activism, which, in turn, encourages broader civic engagement. The discussion focuses on theoretical implications for understanding the impact of personality on different forms of citizenship behaviors and of the applicability of the Volunteer Process Model for studying political activity and civic engagement. 相似文献