全文获取类型
收费全文 | 10172篇 |
免费 | 597篇 |
国内免费 | 7篇 |
出版年
2023年 | 136篇 |
2022年 | 171篇 |
2021年 | 219篇 |
2020年 | 321篇 |
2019年 | 317篇 |
2018年 | 519篇 |
2017年 | 551篇 |
2016年 | 496篇 |
2015年 | 309篇 |
2014年 | 366篇 |
2013年 | 1341篇 |
2012年 | 702篇 |
2011年 | 705篇 |
2010年 | 444篇 |
2009年 | 295篇 |
2008年 | 572篇 |
2007年 | 487篇 |
2006年 | 444篇 |
2005年 | 338篇 |
2004年 | 261篇 |
2003年 | 250篇 |
2002年 | 211篇 |
2001年 | 114篇 |
2000年 | 132篇 |
1999年 | 90篇 |
1998年 | 58篇 |
1997年 | 46篇 |
1996年 | 47篇 |
1995年 | 44篇 |
1994年 | 37篇 |
1993年 | 43篇 |
1992年 | 52篇 |
1991年 | 54篇 |
1990年 | 45篇 |
1989年 | 44篇 |
1988年 | 43篇 |
1987年 | 31篇 |
1986年 | 30篇 |
1985年 | 30篇 |
1984年 | 29篇 |
1983年 | 22篇 |
1981年 | 19篇 |
1980年 | 17篇 |
1979年 | 26篇 |
1976年 | 20篇 |
1971年 | 17篇 |
1970年 | 16篇 |
1968年 | 20篇 |
1966年 | 16篇 |
1965年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
André M. van der Laan René Veenstra Stefan Bogaerts Frank C. Verhulst Johan Ormel 《Journal of abnormal child psychology》2010,38(3):339-351
This study uses a social-ecological approach to the development of delinquency. The authors emphasize that a balance between
eliminating risk and enhancing protection across domains is essential in reducing problems and promoting competence. The cumulative
risk and promotive effects of temperament, family and school factors in preadolescence were examined on different groups of
delinquents (based on self-report) in early adolescence. Data from the first two waves of the TRAILS study (N = 2,230) were used. The results provide evidence for a compensatory model that assumes main effects of risk and promotive
factors on problem behavior. Accumulation of risks in preadolescence promoted being a serious delinquent in early adolescence,
with the strongest effects for temperament. Accumulation of promotive effects decreased being a delinquent and supported being
a non-delinquent. Furthermore, evidence is found for a counter-balancing effect of cumulative promotive and risk factors.
Exposure to more promotive domains in the relative absence of risk domains decreased the percentage of serious delinquents.
Our results did not support a protective model. Implications for prevention and intervention are discussed. 相似文献
992.
Amandine Afonso Alan Blum Brian F. G. Katz Philippe Tarroux Grégoire Borst Michel Denis 《Memory & cognition》2010,38(5):591-604
When people scan mental images, their response times increase linearly with increases in the distance to be scanned, which
is generally taken as reflecting the fact that their internal representations incorporate the metric properties of the corresponding
objects. In view of this finding, we investigated the structural properties of spatial mental images created from nonvisual
sources in three groups (blindfolded sighted, late blind, and congenitally blind). In Experiment 1, blindfolded sighted and
late blind participants created metrically accurate spatial representations of a small-scale spatial configuration under both
verbal and haptic learning conditions. In Experiment 2, late and congenitally blind participants generated accurate spatial
mental images after both verbal and locomotor learning of a full-scale navigable space (created by an immersive audio virtual
reality system), whereas blindfolded sighted participants were selectively impaired in their ability to generate precise spatial
representations from locomotor experience. These results attest that in the context of a permanent lack of sight, encoding
spatial information on the basis of the most reliable currently functional system (the sensorimotor system) is crucial for
building a metrically accurate representation of a spatial environment. The results also highlight the potential of spatialized
audio-rendering technology for exploring the spatial representations of visually impaired participants. 相似文献
993.
Tamra J. Bireta Sheena E. Fry Annie Jalbert Ian Neath Aimée M. Surprenant Gerald Tehan Georgina Anne Tolan 《Memory & cognition》2010,38(3):279-291
Working memory was designed to explain four benchmark memory effects: the word length effect, the irrelevant speech effect, the acoustic confusion effect, and the concurrent articulation effect. However, almost all research thus far has used tests that emphasize forward recall. In four experiments, we examine whether
each effect is observable when the items are recalled in reverse order. Subjects did not know which recall direction would
be required until the time of test, ensuring that encoding processes would be identical for both recall directions. Contrary
to predictions of both the primacy model and the feature model, the benchmark memory effect was either absent or greatly attenuated
with backward recall, despite being present with forward recall. Direction of recall had no effect on the more difficult conditions
(e.g., long words, similar-sounding items, items presented with irrelevant speech, and items studied with concurrent articulation).
Several factors not considered by the primacy and feature models are noted, and a possible explanation within the framework
of the SIMPLE model is briefly presented. 相似文献
994.
Josée Poirier Katie Wolfinger Lisa Spellman Lewis P. Shapiro 《Journal of psycholinguistic research》2010,39(5):411-427
Ellipsis refers to an element that is absent from the input but whose meaning can nonetheless be recovered from context. In
this cross-modal priming study, we examined the online processing of Sluicing, an ellipsis whose antecedent is an entire clause:
The handyman threw a book to the programmer but I don’t know which book the handyman threw to the programmerellipsis. To understand such an elliptical construction, the listener arguably must ‘fill in’ the missing material (“the handyman threw___
to the programmer”) based on that which occurs in the antecedent clause. We aimed to determine the point in time in which
reconstruction of the sluiced sentence is attempted and whether such a complex antecedent is re-accessed by the ellipsis.
Out of the two antecedent constituents for which we probed, only the Object (programmer) was found active in the elliptical clause, confirming that an antecedent is attributed to the sluice in real time. Possible
reasons for the non-observation of the Subject (handyman) are considered. We also suggest that ellipses are detected earlier in coordinated than subordinated sentences. 相似文献
995.
Referring to studies about addictive behaviors, the objective of this article is to present the validation of a new tool for the assessment of the addictive behaviors with or without substances: the Addictive Intensity Evaluation Questionnaire (AIEQ). Twelve different versions of the AIEQ have been administered to 354 participants in order to assess their addictive behaviors. The study of the factorial structure of the questionnaire and its reliability allow us considering the psychometric qualities of the AIEQ as satisfactory. The results suggest the existence of a continuum between the absence of addiction and the severe forms of addiction. The discussion section proposes a classification based on the severity of the addictive behaviors and applications of the use of the AIEQ. 相似文献
996.
Dave Holmes Amélie M Perron Marc Savoie 《Philosophy, ethics, and humanities in medicine : PEHM》2006,1(1):12-6
This article outlines the struggle between the power of the health care professional and the rights of the individual to choose
freely a modality of treatment. Nurses are instrumental in assisting patients in making the best decision for a therapy they
will have to assume for the rest of their lives. In guiding patients' decision, nurses must take into account these unavoidable
contingencies: changes in lifestyle, nutritional restrictions, level of acceptance, compliance issues, ease of training and
availability of support/facilities. Ensuring that the patient makes an informed decision is therefore an ongoing challenge
for nurses as they are taking part in a delicate balancing act between not directly influencing the patient's decision while
making sure the patient is accurately informed. 相似文献
997.
S. Miro J.-M. Costantini S. Sorieul L. Gosmain L. Thomé 《Philosophical Magazine Letters》2013,93(11):633-639
Single crystals of 6H–SiC were implanted at room temperature with 4-MeV Au ions to a fluence of 1015?cm?2. Raman spectra showed that full amorphization was achieved. The recrystallization process was studied by micro-Raman spectrometry after isochronal thermal annealing between 700 and 1500°C. The spectra permitted the evolution upon annealing of Si–C bonds, and also of Si–Si and C–C bonds, to be followed. Amorphous phase relaxation takes place below 700°C; then recrystallization of the 6H polytype sets in at 700°C. At 900°C crystallites with different crystalline states are formed. Moreover, Raman spectra provide evidence of graphitic nanocluster formation at 1500°C. 相似文献
998.
A. Concustell F.O. Méar S. Suriñach M.D. Baró A.L. Greer 《Philosophical Magazine Letters》2013,93(12):831-840
The metallic glass Pd40Cu30Ni10P20 in as-cast or pre-annealed states was shot-peened successively at room temperature or at 77 K. The structural state of the glass was characterized by the relaxation spectrum measured in a differential scanning calorimeter. Mechanically induced relaxation of the as-cast glass and mechanically induced rejuvenation of pre-annealed samples are both more evident at 77 K than at 298 K, enabling deductions about the underlying mechanisms. The relaxation spectrum of the glass as a function of temperature displays two broad maxima, which occurring at the higher temperature is attributed to the part of the free-volume distribution associated with flow defects. In samples shot-peened at 77 K, the stored energy after deformation can be as high as 20% of the cold work. Shot-peening simultaneously generates flow defects within shear bands and destroys them in the matrix between bands: whose effect dominates is principally dependent on the initial state of relaxation of the glass. Shot-peening of partially crystallized samples appears capable of breaking up and dispersing crystallites without inducing any further significant crystallization. 相似文献
999.
Sébastien Allain Frédéric Danoix Mohamed Goune Khalid Hoummada Dominique Mangelinck 《Philosophical Magazine Letters》2013,93(2):68-76
The work-hardening behaviour of virgin martensitic steel has been investigated in a strictly un-aged state and after various ageing conditions. At room temperature (RT), the un-aged alloy shows astonishing tensile performances (ultimate tensile stress?=?1600?MPa/uniform elongation?=?15%) but unexpected serrations. These serrations can be suppressed by static ageing (at RT or higher) while maintaining the initial work-hardening rate (ageing at RT). Parallel investigations using atom probe tomography reveal that the distribution of carbon at the atomic scale evolves from purely homogeneous for virgin martensite to partly segregated at a very fine scale (5–10?nm) after static ageing. This particular mechanical behaviour can therefore be associated with a very local decrease in available carbon in solid solution due to redistribution and segregations on defects (nanotwins) that occurs rapidly, even after few days at RT. 相似文献
1000.
Antoine Jérusalem 《Philosophical Magazine Letters》2013,93(9):599-609
Owing to their very high strength, nanocrystalline metals have been extensively studied over the recent years. The direct Hall–Petch law, empirically proportioning the material strength to the inverse square root of its grain size has been shown to break down below a grain size of the order of tenths of nanometers. This phenomenon has been widely rationalized as a gradual switch from intragrain mediated deformation mechanisms to grain boundary mediated deformation mechanisms. This transition has been observed in many finite element simulations, despite the intrinsic restriction of necessarily limiting the nanocrystalline representative assembly to only a few grains. Such a limitation is generally overlooked, and its influence on an uniaxial tension test – when compared to a complete sample of millions of grains – ignored. We propose here to quantify the approximation done by considering a finite number of grains by means of a simple analytical model based on the early work of Stevens [R.N. Stevens, Philos. Mag. 23 (1971) p. 265]. The finite element approximation is demonstrated to be relatively good, even down to only three grains in width, and a method to “correct” the stress-strain curves of small representative volumes is proposed. 相似文献