全文获取类型
收费全文 | 21007篇 |
免费 | 554篇 |
国内免费 | 24篇 |
学科分类
工业技术 | 21585篇 |
出版年
2022年 | 148篇 |
2021年 | 242篇 |
2020年 | 198篇 |
2019年 | 265篇 |
2018年 | 297篇 |
2017年 | 302篇 |
2016年 | 366篇 |
2015年 | 292篇 |
2014年 | 457篇 |
2013年 | 1241篇 |
2012年 | 750篇 |
2011年 | 944篇 |
2010年 | 755篇 |
2009年 | 762篇 |
2008年 | 887篇 |
2007年 | 953篇 |
2006年 | 787篇 |
2005年 | 741篇 |
2004年 | 652篇 |
2003年 | 609篇 |
2002年 | 586篇 |
2001年 | 365篇 |
2000年 | 365篇 |
1999年 | 362篇 |
1998年 | 453篇 |
1997年 | 394篇 |
1996年 | 378篇 |
1995年 | 365篇 |
1994年 | 313篇 |
1993年 | 360篇 |
1992年 | 317篇 |
1991年 | 228篇 |
1990年 | 276篇 |
1989年 | 283篇 |
1988年 | 272篇 |
1987年 | 260篇 |
1986年 | 282篇 |
1985年 | 301篇 |
1984年 | 300篇 |
1983年 | 295篇 |
1982年 | 233篇 |
1981年 | 263篇 |
1980年 | 255篇 |
1979年 | 255篇 |
1978年 | 228篇 |
1977年 | 229篇 |
1976年 | 207篇 |
1975年 | 198篇 |
1974年 | 175篇 |
1973年 | 180篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
We derive an effective single-band Hubbard type Hamiltonian for CuO2 planes. The Hamiltonian includes both electron-electron repulsion and electron-phonon coupling to oxygen vibrational modes. We start with first-principles density functional theory parameters and then map onto a single-band model. Unlike previous mappings to a single-band Hamiltonian, ours explicitly preserves the Fermi surface shape and matrix elements of the many-band Hamiltonian. We consider both in-plane oxygen breathing modes as well as out-of-plane tilting modes. The latter modes have a quadratic electron-phonon coupling, and are also highly anharmonic in La2CuO4 based superconductors. The coupling to breathing modes is too small to account for highT
c, while the coupling to quadratic modes is much stronger even though they would be neglected in a standard Migdal-Eliashberg approach to superconductivity. 相似文献
72.
F. L. Schmidt and J. E. Hunter (1989) critiqued the within-group interrater reliability statistic (rwg) described by L. R. James et al (1984). S. W. Kozlowski and K. Hattrup (1992) responded to the Schmidt and Hunter critique and argued that rwg is a suitable index of interrater agreement. This article focuses on the interpretation of rwg as a measure of agreement among judges' ratings of a single target. A new derivation of rwg is given that underscores this interpretation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Perri Michael G.; McAllister David A.; Gange James J.; Jordan Randall C.; McAdoo W. George; Nezu Arthur M. 《Canadian Metallurgical Quarterly》1988,56(4):529
This study evaluated the effectiveness of four posttreatment programs designed to enhance the long-term maintenance of weight loss. Mildly and moderately obese adults (N?=?123) were randomly assigned to one of the following five conditions: (a) behavior therapy only; (b) behavior therapy plus a posttreatment therapist-contact maintenance program; (c) behavior therapy plus posttreatment therapist contact plus a social influence maintenance program; (d) behavior therapy plus posttreatment therapist contact plus an aerobic exercise maintenance program; or (e) behavior therapy plus posttreatment therapist contact plus both the aerobic exercise and social influence maintenance programs. All posttreatment programs were conducted in 26 biweekly sessions during the year following behavioral treatment for obesity. At an 18-month follow-up evaluation, all four conditions that combined behavior therapy with a posttreatment maintenance program yielded significantly greater long-term weight losses than behavior therapy alone. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
75.
Ockene Judith K.; Kristeller Jean; Pbert Lori; Hebert James R.; Luippold Rose; Goldberg Robert J.; Landon Joan; Kalan Kathryn 《Canadian Metallurgical Quarterly》1994,13(3):278
Patterns of smoking cessation using 6- and 12-mo follow-up data are reported for 1,261 primary care patients randomized to 3 physician-delivered smoking interventions: advice only (AO), counseling (CI), and counseling plus availability of nicotine-containing gum (CI?+?NCG). One-week point-prevalence cessation rates at 12 mo did not differ among the interventions: AO (15.2%), CI (12.9%) and CI?+?NCG (16.7%). However, maintained cessation rates (abstinent at both 6 and 12 mo) increased with intervention intensity: AO (6.0%), CI (7.8%), and CI?+?NCG (10.0%): Test of trend χ–2?=?5.06, p?=?.02. CI?+?NCG was significantly higher than AO (p?=?.02). The findings support the following conclusions: Brief physician delivered intervention with availability of nicotine-containing gum can have a beneficial long-term effect on smoking cessation, and cohort data as well as point-prevalence rates are important when assessing the long-term impact of lifestyle interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Examined the emotional similarity hypothesis, a derivation from social comparison theory, which predicts that increasing fear should lead to greater affiliation with someone who is awaiting the same threat (and who therefore is of relatively similar emotional status) relative to someone who has already experienced the threat (and who therefore is of relatively dissimilar emotional status). Results failed to support the emotional similarity hypothesis and in so doing challenged the importance of emotional comparison as a determinant of verbal affiliation under threat. Cognitive clarity concerns instead seemed to account better for the observed effects on verbal affiliation. Supplementary analyses of nonverbal affiliation (facial glances) likewise ran counter to an emotional similarity prediction. Effects of affiliation on anxiety were also examined. Previous conclusions regarding the pattern and causes of affiliation under threat that have relied on the affiliate-choice paradigm are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
Describes the content, process, and functions of universal definitions as used in psychotherapy. In the Socratic method, systematic questioning and inductive reasoning are used jointly to derive a universal definition. The content of universal definitions focuses on behavior labels (e.g., aggressive), evaluative standards (e.g., success), and abstract qualities (e.g., love). The process of using universal definitions in psychotherapy follows refutation, collection, and division to identify the essence of the concept. The functions of universal definitions include clarifying category membership, identifying potential causes, building new knowledge, broadening the client's perspective, limiting overgeneralizations, and guiding behavior change. Through the Socratic method, clients learn how to explore general emotional and interpersonal issues in an independent manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
78.
Encoding briefly displayed arrays of multidimensional objects appears to require selective attention, but this hypothesis is challenged by M. J. Nissen's (1985) finding that properties of an object are reported independently. Selective attention to some objects but not others should produce positive dependence. Theoretical analysis shows that deviations from independence would have been difficult to observe in Nissen's data because of high guessing rates and small sample sizes. Four new experiments showing strong positive dependence in property reports are described. Deviations from independence were highly significant for most Ss. Quantitative modeling shows that selective attention to subsets of objects would produce about the amount of dependence obtained. Rather than challenging attention theories, the amount of dependence in encoding multidimensional objects is consistent with selective attention to either objects or locations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
80.