全文获取类型
收费全文 | 1539篇 |
免费 | 24篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 18篇 |
综合类 | 4篇 |
化学工业 | 306篇 |
金属工艺 | 17篇 |
机械仪表 | 36篇 |
建筑科学 | 39篇 |
矿业工程 | 10篇 |
能源动力 | 39篇 |
轻工业 | 108篇 |
水利工程 | 23篇 |
石油天然气 | 6篇 |
无线电 | 91篇 |
一般工业技术 | 208篇 |
冶金工业 | 476篇 |
原子能技术 | 16篇 |
自动化技术 | 168篇 |
出版年
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 17篇 |
2017年 | 18篇 |
2016年 | 7篇 |
2015年 | 16篇 |
2014年 | 24篇 |
2013年 | 58篇 |
2012年 | 39篇 |
2011年 | 57篇 |
2010年 | 41篇 |
2009年 | 48篇 |
2008年 | 54篇 |
2007年 | 53篇 |
2006年 | 46篇 |
2005年 | 41篇 |
2004年 | 33篇 |
2003年 | 34篇 |
2002年 | 43篇 |
2001年 | 35篇 |
2000年 | 25篇 |
1999年 | 35篇 |
1998年 | 101篇 |
1997年 | 62篇 |
1996年 | 52篇 |
1995年 | 39篇 |
1994年 | 37篇 |
1993年 | 40篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 37篇 |
1989年 | 36篇 |
1988年 | 36篇 |
1987年 | 22篇 |
1986年 | 20篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 17篇 |
1982年 | 22篇 |
1981年 | 25篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1978年 | 19篇 |
1977年 | 16篇 |
1976年 | 27篇 |
1975年 | 14篇 |
1974年 | 13篇 |
1973年 | 17篇 |
1972年 | 7篇 |
1971年 | 8篇 |
排序方式: 共有1565条查询结果,搜索用时 187 毫秒
1.
The effects of circuit weight training on mood, perceived stress, job satisfaction, and physical symptoms were investigated in a sample of state law enforcement officers. 43 male officers who were not regularly exercising were assigned to either 4 mo of circuit weight training or a wait-list control condition. Four months of circuit weight training led to a significant increase in strength on cardiovascular fitness. Ss also demonstrated significant improvements in mood, including decreases in somatization, anxiety, depression, and hostility. Circuit weight training also resulted in a decrease in reports of physical symptoms and in improvements in job satisfaction. Results indicate that Ss who dropped out of the exercise training program evidenced significantly greater anxiety, depression, and hostility at pretreatment than Ss who completed the program. These findings suggest that circuit weight training programs may contribute to important psychological benefits. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
Kunkel Mark A.; Hector Mark A.; Góngora Coronado Elías; Castillo Vales Victor 《Canadian Metallurgical Quarterly》1989,36(3):322
Conducted a study of client expectations of psychological services in Yucatán, Mexico, under the sponsorship of a grant from the Organization of American States. The Expectations about Counseling–Brief form (EAC-B) questionnaire was translated and administered to 488 subjects across age, sex, and experience with psychological services. Subsequent analyses supported the reliability and robustness of the Spanish EAC-B, with factor structure similar to the EAC-B in English. Some relation was found among age, sex, prior counseling experience, and expectations about counseling. Implications of these data for future research and comparison with U.S. subjects are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Hadjem A. Lautru D. Dale C. Man Fai Wong Hanna V.F. Wiart J. 《Microwave Theory and Techniques》2005,53(1):4-11
This paper gives a first comparison of specific absorption rate (SAR) induced in a child-sized (CS) head and an adult head using a dual-band mobile phone. In the second study, the visible human head is considered and comparison of SAR induced in a CS or child-like (CL) head and an adult head using a dual-band mobile phone is given. All the peaks of average SAR over a mass of 10 and 1 g in the head and the power budget are determined in the two comparisons using the finite-difference time-domain method. The differences between the results for adult and CS or CL heads are given at 900 and 1800 MHz. No important differences are noted for the peak SAR averaged over 10 g (SAR10 g), between the two adult head models, as well as between the two child head models. The peak SAR10 g in the brain of the CS or CL head is slightly more significant than that for the adult one. 相似文献
4.
Healing substrates with mobile, particle-filled microcapsules: designing a 'repair and go' system. 下载免费PDF全文
Rolf Verberg Alex T Dale Prashant Kumar Alexander Alexeev Anna C Balazs 《Journal of the Royal Society Interface》2007,4(13):349-557
We model the rolling motion of a fluid-driven, particle-filled microcapsule along a heterogeneous, adhesive substrate to determine how the release of the encapsulated nanoparticles can be harnessed to repair damage on the underlying surface. We integrate the lattice Boltzmann model for hydrodynamics and the lattice spring model for the micromechanics of elastic solids to capture the interactions between the elastic shell of the microcapsule and the surrounding fluids. A Brownian dynamics model is used to simulate the release of nanoparticles from the capsule and their diffusion into the surrounding solution. We focus on a substrate that contains a damaged region (e.g. a crack or eroded surface coating), which prevents the otherwise mobile capsule from rolling along the surface. We isolate conditions where nanoparticles released from the arrested capsule can repair the damage and thereby enable the capsules to again move along the substrate. Through these studies, we establish guidelines for designing particle-filled microcapsules that perform a 'repair and go' function and thus, can be utilized to repair damage in microchannels and microfluidic devices. 相似文献
5.
Haley William E.; Larson Dale G.; Kasl-Godley Julia; Neimeyer Robert A.; Kwilosz Donna M. 《Canadian Metallurgical Quarterly》2003,34(6):626
Professional psychologists are increasingly likely to encounter opportunities to work with patients and families facing end-of-life issues. Psychologists can provide psychological assessment, intervention for patients and families, consultation with and support of health care team members, grief therapy, and program development and evaluation. Psychological services are useful for healthy individuals who wish to make thoughtful plans about their own future care, patients with life-limiting illnesses, families stressed by providing end-of-life care, bereaved individuals, and health care providers who face issues of burnout and strain. Several challenges for psychologists working in end-of-life care are noted, including training, development of clear roles, and reimbursement. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
7.
8.
Nitrogen addition to iron powder by mechanical alloying 总被引:3,自引:0,他引:3
Nitrogen was alloyed into iron (a) by mechanical processing in a nitrogen gas environment, and (b) by mechanically alloying with iron-nitride powders to characterize resulting nano-structure and nitrogen distribution. Although the infused nitrogen concentration was significantly greater than the thermodynamic equilibrium solubility of iron, no nitrides formed, even for nitrogen concentrations as high as 4.1 wt.% However, a bctFe phase did form. Lattice expansion calculations indicate that the sum of the interstitial bcc-Fe and bctFe nitrogen concentrations was significantly less than the total measured nitrogen concentration. A considerable portion of the mechanically infused nitrogen was determined to be associated with nanograin boundaries. 相似文献
9.
A new multivariable adaptive nonlinear predictive controller is designed using a general nonlinear input-output model and variable transformations. The controller is similar in form to typical linear predictive controllers can be tuned analogously or by specifying a single parameters for each controlled variable. In addition, the design procedure is computationally efficient. The new controller is compared to a multi-loop proportional-integral (PI) controller with one-way static decoupling and to an adaptive linear predictive controller through tests on a simulated nonlinear distillation column. The new controller performed well in an experimental application to a multicomponent distillation column. 相似文献
10.
Develops 3 hypotheses to explain the role of construal processes in conformity behavior. According to the preconformity change of meaning hypothesis, social influence leads to changes in situational construal that precede and mediate conformity behavior; according to the postconformity change of meaning hypothesis, construal change follows and justifies conformity; and according to the construal-consistency hypothesis, preexisting situational construal distinguishes those who conform from those who dissent. Four experimental studies with varying methodology and involving a total of 361 undergraduate students were performed to test these hypotheses. The results of all studies provide strong evidence for postconformity change of meaning effects. Discussion centers on possible domains in which the different construal mechanisms might operate. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献