全文获取类型
收费全文 | 2228篇 |
免费 | 77篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 29篇 |
综合类 | 6篇 |
化学工业 | 496篇 |
金属工艺 | 56篇 |
机械仪表 | 25篇 |
建筑科学 | 118篇 |
矿业工程 | 10篇 |
能源动力 | 96篇 |
轻工业 | 136篇 |
水利工程 | 6篇 |
石油天然气 | 15篇 |
无线电 | 158篇 |
一般工业技术 | 327篇 |
冶金工业 | 478篇 |
原子能技术 | 24篇 |
自动化技术 | 337篇 |
出版年
2022年 | 29篇 |
2021年 | 38篇 |
2020年 | 25篇 |
2019年 | 25篇 |
2018年 | 33篇 |
2017年 | 35篇 |
2016年 | 32篇 |
2015年 | 34篇 |
2014年 | 48篇 |
2013年 | 220篇 |
2012年 | 71篇 |
2011年 | 82篇 |
2010年 | 90篇 |
2009年 | 83篇 |
2008年 | 94篇 |
2007年 | 76篇 |
2006年 | 56篇 |
2005年 | 62篇 |
2004年 | 50篇 |
2003年 | 47篇 |
2002年 | 41篇 |
2001年 | 36篇 |
2000年 | 20篇 |
1999年 | 35篇 |
1998年 | 74篇 |
1997年 | 48篇 |
1996年 | 49篇 |
1995年 | 50篇 |
1994年 | 38篇 |
1993年 | 43篇 |
1992年 | 28篇 |
1991年 | 28篇 |
1990年 | 36篇 |
1989年 | 18篇 |
1988年 | 22篇 |
1987年 | 27篇 |
1986年 | 33篇 |
1985年 | 21篇 |
1984年 | 30篇 |
1983年 | 26篇 |
1982年 | 28篇 |
1981年 | 33篇 |
1980年 | 20篇 |
1979年 | 20篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 18篇 |
1975年 | 31篇 |
1974年 | 19篇 |
1973年 | 17篇 |
排序方式: 共有2317条查询结果,搜索用时 265 毫秒
1.
AI & SOCIETY - This paper is addressed to recent theoretical discussions of the Anthropocene, in particular Bernard Stiegler’s Neganthropocene (Open Universities Press, 2018), which... 相似文献
2.
3.
The intent of a binomial effect size display (BESD) is to show "the [real-world] importance of [an] effect indexed by a correlation [r]" (R. Rosenthal, 1994, p. 242) by reexpressing this correlation as a success rate difference (SRD) (e.g., treatment group success rate - control group success rate). However, SRDs displayed in BESDs generally overestimate real-world SRDs implied by correlations of (a) dichotomous X and Y variables (φ coefficients), (b) dichotomous X and continuous Y variables (point-biserial coefficients [rphs]). and (c) continuous X and Y variables (rxys). Furthermore, overestimation biases are larger for rxys than for rphs. Differences in the sizes of biases linked to different correlations suggest that BESD SRDs reported for different correlations are not comparable. The stochastic difference index (N. Cliff, 1993: A. Vargha & H. D. Delaney, 2000) is recommended as an alternative to the BESD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
A revised methodology is described for research on metacognitive monitoring, especially judgments of learning (JOLs), to investigate psychological processing that previously has been only hypothetical and unobservable. During data collection a new stage of recall occurs just prior to the JOL, so that during data analysis the items can be partitioned into subcategories to measure the degree of JOL accuracy in ways that are more analytic than was previously possible. A weighted-average combinatorial rule allows the component measures of JOL accuracy to be combined into the usual overall measure of metacognitive accuracy. An example using the revised methodology offers a new explanation for the delayed-JOL effect, in which delayed JOLs are more accurate than immediate JOLs for predicting recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
John C. Hart Gordon W. Lescinsky Daniel J. Sandin Thomas A. DeFanti Louis H. Kauffman 《The Visual computer》1993,9(7):346-355
The pipelined architecture and parallel organization of the AT&T Pixel Machine image computer are described and demonstrated with applications for the visualization of multidimensional fractals, particularly linear fractals and quaternion/ stacked Julia sets. Techniques for pushing the Pixel Machine to its peak abilities are described and apply to more recent parallel image computers as well. 相似文献
6.
The skeletal muscle relaxant dantrolene inhibits the release of Ca2+ from the sarcoplasmic reticulum during excitation-contraction coupling and suppresses the uncontrolled Ca2+ release that underlies the skeletal muscle pharmacogenetic disorder malignant hyperthermia; however, the molecular mechanism by which dantrolene selectively affects skeletal muscle Ca2+ regulation remains to be defined. Here we provide evidence of a high-affinity, monophasic inhibition by dantrolene of ryanodine receptor Ca2+ channel function in isolated sarcoplasmic reticulum vesicles prepared from malignant hyperthermia-susceptible and normal pig skeletal muscle. In media simulating resting myoplasm, dantrolene increased the half-time for 45Ca2+ release from both malignant hyperthermia and normal vesicles approximately 3.5-fold and inhibited sarcoplasmic reticulum vesicle [3H]ryanodine binding (Ki approximately 150 nM for both malignant hyperthermia and normal). Inhibition of vesicle [3H]ryanodine binding by dantrolene was associated with a decrease in the extent of activation by both calmodulin and Ca2+. Dantrolene also inhibited [3H]ryanodine binding to purified skeletal muscle ryanodine receptor protein reconstituted into liposomes. In contrast, cardiac sarcoplasmic reticulum vesicle 45Ca2+ release and [3H]ryanodine binding were unaffected by dantrolene. Together, these results demonstrate selective effects of dantrolene on skeletal muscle ryanodine receptors that are consistent with the actions of dantrolene in vivo and suggest a mechanism of action in which dantrolene may act directly at the skeletal muscle ryanodine receptor complex to limit its activation by calmodulin and Ca2+. The potential implications of these results for understanding how dantrolene and malignant hyperthermia mutations may affect the voltage-dependent activation of Ca2+ release in intact skeletal muscle are discussed. 相似文献
7.
This paper presents new inverse modeling for synchronous reluctance motor (SyRM). This modeling is valid when the inductances are sinusoidal or nonsinusoidal and even when the machine is saturated. This technique involves the generation of constant torque curves as a function of two-phase currents in the Concordia's reference frame when the rotor angle is fixed. We also introduce an experimental method to obtain directly the inverse modeling. This practical method takes into account the saturation of the motor. This technique allows the reduction of the low torque ripple in the case of nonsinusoidal inductances. 相似文献
8.
9.
A REVIEW OF PRODUCTION PLANNING AND SCHEDULING MODELS IN THE SEMICONDUCTOR INDUSTRY PART I: SYSTEM CHARACTERISTICS, PERFORMANCE EVALUATION AND PRODUCTION PLANNING 总被引:10,自引:0,他引:10
Although the national importance of the semiconductor industry is widely acknowledged, it is only recently that the production planning and scheduling problems encountered in this environment have begun to be addressed using industrial engineering and operations research.techniques. These problems have several features that make them difficult and challenging: random yields and rework, complex product flows, and rapidly changing products and technologies. Hence their solution will contribute considerably to die theory and practice of production planning and control. In a two-part project we present a review of research in this area to date, discuss the applicability of the various approaches and suggest directions for future research. In this paper, Part I, we describe the characteristics of the semiconductor manufacturing environment and review models related to performance evaluation and production planning. Part II will review research on shop-floor control in this industry to date. 相似文献
10.
PH Kilmarx AA Zaidi JC Thomas AK Nakashima ME St Louis ML Flock TA Peterman 《Canadian Metallurgical Quarterly》1997,87(12):1937-1943
OBJECTIVES: Syphilis in the United States is focally distributed, with high incidence rates in the South and in metropolitan areas nationwide. In this study an ecological analysis, using the county as the unit of analysis, was performed to generate hypotheses about community-level determinants of syphilis rates. METHODS: Bivariate rank correlations and multivariate, backward stepwise elimination linear regressions were performed. Mean annual incidence of primary- and secondary-stage syphilis in a county was the dependent variable, and county sociodemographic characteristics (from census data) were the independent variables. RESULTS: In the multivariate regression model, sociodemographic characteristics accounted for 71% of the variation in syphilis rates among counties. With other factors accounted for, the most highly correlated characteristics were percentage non-Hispanic Black population, county location in the South, percentage of the population that was urban, percentage Hispanic population, and percentage of births to women younger than 20 years. CONCLUSIONS: Most of the variation in syphilis rates among counties is accounted for by sociodemographic characteristics. Identification and remediation of modifiable health determinants for which these factors are markers are needed to improve the health status of these populations. 相似文献