全文获取类型
收费全文 | 3285篇 |
免费 | 113篇 |
国内免费 | 39篇 |
专业分类
电工技术 | 96篇 |
综合类 | 39篇 |
化学工业 | 794篇 |
金属工艺 | 76篇 |
机械仪表 | 137篇 |
建筑科学 | 111篇 |
矿业工程 | 24篇 |
能源动力 | 95篇 |
轻工业 | 283篇 |
水利工程 | 26篇 |
石油天然气 | 10篇 |
武器工业 | 2篇 |
无线电 | 289篇 |
一般工业技术 | 464篇 |
冶金工业 | 372篇 |
原子能技术 | 47篇 |
自动化技术 | 572篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 40篇 |
2021年 | 65篇 |
2020年 | 30篇 |
2019年 | 58篇 |
2018年 | 68篇 |
2017年 | 45篇 |
2016年 | 63篇 |
2015年 | 67篇 |
2014年 | 87篇 |
2013年 | 181篇 |
2012年 | 144篇 |
2011年 | 213篇 |
2010年 | 201篇 |
2009年 | 218篇 |
2008年 | 223篇 |
2007年 | 186篇 |
2006年 | 151篇 |
2005年 | 167篇 |
2004年 | 107篇 |
2003年 | 112篇 |
2002年 | 108篇 |
2001年 | 70篇 |
2000年 | 62篇 |
1999年 | 54篇 |
1998年 | 96篇 |
1997年 | 78篇 |
1996年 | 75篇 |
1995年 | 49篇 |
1994年 | 46篇 |
1993年 | 49篇 |
1992年 | 34篇 |
1991年 | 27篇 |
1990年 | 27篇 |
1989年 | 17篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 28篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1982年 | 12篇 |
1981年 | 19篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1973年 | 3篇 |
排序方式: 共有3437条查询结果,搜索用时 15 毫秒
21.
Ahluwalia Jasjit S.; Nollen Nicole; Kaur Harsohena; James Aimee S.; Mayo Matthew S.; Resnicow Ken 《Canadian Metallurgical Quarterly》2007,26(2):214
Objectives: Examine the effectiveness of an intervention to increase fruits and vegetables (FV) consumption among smokers. Design: Cluster-randomized trial of 20 public housing developments; 10 randomly assigned to an FV intervention and 10 to a smoking cessation intervention. Main outcome measures: Usual (past 7 days) and past 30 days change in daily FV intake at 8 weeks and 6 months postbaseline. Results: Greater increases were seen in the FV group. At Week 8 and Month 6, the FV group had consumed 1.58 (p = .001) and 0.78 (p = .04), respectively, more daily FV servings in the past 7 days than the cessation group. At the same time points, the FV group had consumed 3.61 (p = .01) and 3.93 (p = .01), respectively, more FV servings in the past 30 days than the cessation group. Completing more motivational interviewing sessions (p = .02) and trying more recipes (p = .02) led to significantly greater increases at Month 6 among FV participants. Conclusions: Motivational interviewing counseling and lifestyle modification through trying out healthy recipes may be effective in helping a high-risk population increase their FV intake. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
22.
23.
Argues that psychoanalysts have repeatedly attempted to (dis)locate homosexuals within a theory of gender that rests on essential distinctions between what is feminine and what is masculine. The best illustration of this (dis)location is the manner in which the male homosexual has been regarded as feminine. Calling gay men feminine neither sufficiently problematizes their experience of gender nor adequately captures the vicissitudes of gender. The author contends that male homosexuality is a differently structured masculinity, not a simulated femininity. Though both heterosexual and homosexual men readily identify themselves as men, the gay man's gender identity is distinguished by his experience of passivity in relation to another man. A crucial step in the treatment of any gay man is the recognition of his early gender experience. The heterosexual male analyst's countertransference difficulties with homosexual male patients are addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
24.
25.
26.
H Koh Y Hashimoto H Takagi K Hirota H Ishihara A Matsuki 《Canadian Metallurgical Quarterly》1993,42(2):217-224
The purpose of the study was to explore the relationship between the exposure of adolescents in the seventh and eighth grades to cigarette advertising and their being smokers. A survey questionnaire given to 602 adolescents assessed their exposure to cigarette advertising and provided measures of their smoking behavior, demographic characteristics, and some psychosocial variables. The results indicated that exposure to cigarette advertising and having friends who smoked were predictive of current smoking status. Adolescents with high exposure to cigarette advertising were significantly more likely to be smokers, according to several measures of smoking behavior, than were those with low exposure to cigarette advertising. The findings extend previous research identifying factors that may play a role in the initiation and maintenance of smoking among adolescents. 相似文献
27.
28.
Ken Smith 《Color research and application》2007,32(4):249-255
This study describes a process of relating the perceptual analysis of the colors of the terrestrial atmosphere to currently available pigments used in artists' painting systems. This process sought to discover how the colors of the sky could be defined and simulated by these pigments. The author also describes how confusion over the bewildering choice of suitable pigments on offer in the market place can be clarified. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 249–255, 2007 相似文献
29.
Lee J. Hatcher G. Vandenberghe L. Chih-Kong Ken Yang 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2007,15(9):1017-1027
This paper presents a feasible study of fully-integrated switching voltage regulators for power-optimized systems-on-chip (SoCs). In order to evaluate the power efficiency across a number of design variables, a compact macro-model of a regulator is created and validated. A key focus of the study is on the characteristics of the active and passive devices that are needed in order to maximize the efficiency of an on-chip regulator. With the macro-model, geometric programming is used to find the optimal characteristics for a given set of constraints such as load condition, process technology, and area. The achievable efficiencies for various current loads and across a range of technologies from 0.35-mum to 90-nm CMOS process are analyzed. The power efficiency is found to be strongly dependent on the inductor technology and over 70% efficiency is possible with advanced inductor technologies. 相似文献
30.
Ming-Ching Lee Chan-Ji Lai Jan-Mou Leu William J. Plant William C. Keller Ken Hayes 《Flow Measurement and Instrumentation》2002,13(5-6):265-270
This article describes a non-contact method for measuring surface velocity and discharge in a natural channel. The X-band pulse (9.36 GHz) radar, developed by the Applied Physics Laboratory of the University of Washington, was used to scan instantaneously the lateral distribution of surface velocity across a river section, according to Bragg scattering from short waves produced by turbulent boils on the surface of the river. Based on the assumption that the vertical velocity distribution follows a universal power or logarithmic law, the discharges were estimated. 相似文献