全文获取类型
收费全文 | 398篇 |
免费 | 2篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 23篇 |
金属工艺 | 6篇 |
机械仪表 | 36篇 |
建筑科学 | 15篇 |
能源动力 | 8篇 |
轻工业 | 24篇 |
水利工程 | 5篇 |
无线电 | 29篇 |
一般工业技术 | 37篇 |
冶金工业 | 152篇 |
原子能技术 | 10篇 |
自动化技术 | 47篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2019年 | 5篇 |
2017年 | 3篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 13篇 |
2011年 | 23篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 25篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 14篇 |
1978年 | 3篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1971年 | 5篇 |
1966年 | 3篇 |
1965年 | 3篇 |
1964年 | 6篇 |
1961年 | 2篇 |
1958年 | 2篇 |
排序方式: 共有400条查询结果,搜索用时 31 毫秒
1.
Glosoff Harriet L.; Herlihy Scott B.; Herlihy Barbara; Spence E. Berton 《Canadian Metallurgical Quarterly》1997,28(6):573
Determining the status of privileged communications between psychologists and clients is a complex task. There is considerable variation across states with respect to the scope of psychologist–client privilege, and several sections of state codes directly and indirectly influence its status. An analysis of state laws related to privileged communication in the psychologist–client relationship is presented and prevalent legal exceptions and trends related to client privilege are discussed. Implications for practice to assist psychologists in balancing their ethical and legal obligations also are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
The inhibition of Ca2+ channel currents by endogenous brain steroids was examined in freshly dissociated pyramidal neurons from the adult guinea pig hippocampal CA1 region. The steady-state inhibition of the peak Ca2+ channel current evoked by depolarizing steps from -80 to -10 mV occurred in a concentration-dependent manner with the following IC50 values: pregnenolone sulfate (PES), 11 nM; pregnenolone (PE), 130 nM; and allotetrahydrocorticosterone (THCC), 298 nM. THCC, PE, and PES depressed a fraction of the Ca2+ channel current with a maximal inhibition of 60% of the total current. However, substitution of an acetate group for the sulfate group on PES resulted in a complete loss of activity. Progesterone had no effect (4% inhibition at 100 microM). Intracellular dialysis of PES had no effect on the Ca2+ current; concomitant extracellular perfusion of PES showed normal inhibitory activity, suggesting that the steroid binding site can only be accessed extracellularly. Analysis of tail currents at -80 mV demonstrated that THCC and PES slowed the rate of Ca2+ current activation and deactivation with no change in the voltage dependence of activation. Inhibition of the Ca2+ channel current by THCC and PES was voltage dependent. THCC primarily inhibits the omega-conotoxin (CgTX)-sensitive or N-type Ca2+ channel current. PE was nonselective in inhibiting both the CgTX- and the nifedipine (NIF)-sensitive Ca2+ channel current. These neurosteroids had no effect on the CgTX/NIF-insensitive current. In neurons isolated from pertussis toxin (PTX)-treated animals by chronic intracerebroventricular infusion (1000 ng/24 hr for 48 hr), the Ca2+ channel current inhibition by PES, PE, and THCC was significantly diminished. Intracellular dialysis with GDP-beta-S (500 microM) also significantly diminished the neurosteroid inhibition of the Ca2+ channel current. Intracellular dialysis with the general kinase inhibitors H-7 (100 microM), staurosporine (400 nM), and a 20 amino acid protein kinase inhibitor (1 microM) also significantly prevented the THCC and PES inhibition of the Ca2+ channel current. Intracellular dialysis with the more specific inhibitors of protein kinase C (PKC), the pseudosubstrate inhibitor (PKCI 19-36) (1-2 microM) and bisindolylmaleimide (1 microM) significantly diminished the THCC and PE inhibition of the Ca2+ channel current. Rp- cAMP (100 microM), a specific inhibitor of cAMP-dependent protein kinase (PKA), had no effect on the THCC and PE inhibition of the Ca2+ current.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
3.
Rajesh R. Shrestha Barrie R. Bonsal Ashish Kayastha Yonas B. Dibike Christopher Spence 《Journal of Great Lakes research》2021,47(3):677-689
This study assesses snow response in the Assiniboine-Red River basin, located in the Lake Winnipeg watershed, due to anthropogenic climate change. We use a process-based distributed snow model driven by an ensemble of eight statistically downscaled global climate models (GCMs) to project future changes under policy-relevant global mean temperature (GMT) increases of 1.0 °C to 3.0 °C above the pre-industrial period. Results indicate that basin scale seasonal warmings generally exceed the GMT increases, with greater warming in winter months. The majority of GCMs project wetter winters and springs, and drier summers, while autumn could become either drier or wetter. An analysis of snow water equivalent (SWE) responses under GMT changes reveal higher correlations of snow cover duration (SCD), snowmelt rate, maximum SWE (SWEmax) and timing of SWEmax with winter and spring temperatures compared to precipitation, implying that these variables are predominantly temperature controlled. Consequently, under the GMT increases from 1.0 °C to 3.0 °C, the basin will experience successively shorter SCD, slower snowmelt, smaller monthly SWE and SWEmax, earlier SWEmax, and a transition from snow-dominated to rain-snow hybrid regime. Further, while the winter precipitation increases for some GCMs compensate the temperature-driven changes in SWE, the increases for most GCMs occur as rainfall, thus limiting the positive contribution to snow storage. Overall, this study provides a detailed diagnosis of the snow regime changes under the policy-relevant GMT changes, and a basis for further investigations on water quantity and quality changes. 相似文献
4.
Acid rain is an important consequence of pollutants generated by modern industrial societies and is known to cause damage to ecological systems, construction materials and cultural artifacts. The assessment of the damage caused to paint films has included laboratory, exposure chamber, and exterior weathering experiments. This study uses visual assessment of paints applied directly to southern yellow pine and exposed at 30° south to either natural acid rain or deionized water spray sites in North Carolina and Ohio to determine damage by acid rain. An acrylic latex paint with a pigment volume concentration (PVC) of 52 and a volume solids (VS) of 35% was formulated with calcium carbonate or sodium potassium alumino-silicate extenders. This high PVC paint formulation is one known to stress the binding capacity of the latex and thus produce early grain cracking failures over bare wood. Major effects observed include severe yellowing and increased mildewing of the carbonate containing paints exposed to acid rain. While acid rain can damage exterior paints, much of the damage can be minimized by careful selection of the polymers and pigments used in the formulation. 相似文献
5.
A sufficiently thin column of liquid was produced to permit penetration with a 200 keV electron beam as evidenced by the observation of diffraction rings due to the intermolecular spacing of the liquid samples. For liquid thickness below 800 nm, the diffraction rings became visible above the inelastic background. Studies were carried out in the environmental chamber of a transmission electron microscope using water and isopropanol. 相似文献
6.
Peter D. Blanken Christopher Spence Newell Hedstrom John D. Lenters 《Journal of Great Lakes research》2011,37(4):707-716
The surface energy balance of Lake Superior was measured using the eddy covariance method at a remote, offshore site at 0.5-h intervals from June 2008 through November 2010. Pronounced seasonal patterns in the surface energy balance were observed, with a five-month delay between maximum summer net radiation and maximum winter latent and sensible heat fluxes. Late season (winter) evaporation and sensible heat losses from the lake typically occurred in two- to three-day-long events, and were associated with significant release of stored heat from the lake. The majority of the evaporative heat loss (70-88%) and sensible heat loss (97-99%) occurred between October and March, with 464 mm (2008-2009) and 645 mm (2009-2010) of evaporative water loss occurring over the water year starting October 1. Evaporation was proportional to the horizontal wind speed, inversely proportional to the ambient vapor pressure, and was well described by the ratio of wind speed to vapor pressure. This ratio remained relatively constant between the two water years, so the differences in evaporative water loss between years were largely associated with differences in lake surface conditions (e.g. water temperature, ice cover, and ice duration). Since late-season water temperature decline is driven by evaporative and sensible heat loss, the potential for a negative feedback mechanism between evaporation and ice cover is discussed. 相似文献
7.
Investigation into pressure pulsations in a centrifugal pump using numerical methods supported by industrial tests 总被引:8,自引:0,他引:8
The operation of centrifugal pumps can generate instabilities and pressure pulsations that may be detrimental to the integrity and performance of the pump. In the present study a numerical investigation of the time variation of pressure within a complete centrifugal pump was undertaken. A range of parameters and three flow rates were investigated and the pulsations were extracted at 15 different locations covering important pump regions. The transient flow results compared reasonably with experimental data obtained in a limited experimental survey and clearly indicated the pump locations experiencing the largest pulsation levels. It was also noted that monitoring pulsations at the top dead centre of the pump volute casing would provide a better indication of internal pump pulsations than monitoring at the discharge. 相似文献
8.
9.
The technology profile inventory (TPI) measures attitudes toward computers and the internet. We describe the most recent phase of the construction of the TPI. The studies reported refine and validate the instrument, and we present the final version as an Appendix A. Using a new sample of respondents (N = 394), we replicated the three major factors found previously (Confidence, Approval, and Interest). The TPI scores were related to patterns of information technology (IT) usage and also to gender. To demonstrate the practical utility of the TPI we report (1) results linking TPI scores to behavior during an internet search task; (2) test–retest results obtained as part of a cognitive training experiment using action video games; and (3) results showing that attitudes to IT may be modified by a particular experience with information technology. 相似文献
10.
Ying K. Leung Robert Spence Mark D. Apperley 《International journal of human-computer interaction》2013,29(1):79-98
Presentation techniques for topological networks can be broadly classified as distortion‐oriented and nondistortion‐oriented. Although there has been a growing interest in applying various distortion‐oriented techniques, the application of an earlier example, the bifocal display, has so far been underexploited. This article describes a number of human‐computer interface techniques potentially relevant to the presentation and navigation of topological networks associated with transport systems, and describes a preliminary experimental study of a number of techniques for presenting the London Underground map as part of a real‐time information system for travelers. 相似文献