全文获取类型
收费全文 | 1823篇 |
免费 | 60篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 24篇 |
综合类 | 1篇 |
化学工业 | 295篇 |
金属工艺 | 24篇 |
机械仪表 | 33篇 |
建筑科学 | 57篇 |
矿业工程 | 4篇 |
能源动力 | 44篇 |
轻工业 | 181篇 |
水利工程 | 9篇 |
石油天然气 | 8篇 |
无线电 | 123篇 |
一般工业技术 | 298篇 |
冶金工业 | 516篇 |
原子能技术 | 20篇 |
自动化技术 | 247篇 |
出版年
2022年 | 20篇 |
2021年 | 18篇 |
2019年 | 10篇 |
2018年 | 20篇 |
2017年 | 34篇 |
2016年 | 34篇 |
2015年 | 34篇 |
2014年 | 40篇 |
2013年 | 95篇 |
2012年 | 60篇 |
2011年 | 75篇 |
2010年 | 80篇 |
2009年 | 57篇 |
2008年 | 64篇 |
2007年 | 50篇 |
2006年 | 52篇 |
2005年 | 34篇 |
2004年 | 51篇 |
2003年 | 64篇 |
2002年 | 49篇 |
2001年 | 33篇 |
2000年 | 43篇 |
1999年 | 36篇 |
1998年 | 125篇 |
1997年 | 70篇 |
1996年 | 58篇 |
1995年 | 39篇 |
1994年 | 36篇 |
1993年 | 29篇 |
1992年 | 28篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 18篇 |
1986年 | 21篇 |
1985年 | 28篇 |
1984年 | 17篇 |
1983年 | 21篇 |
1982年 | 17篇 |
1981年 | 23篇 |
1980年 | 20篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 34篇 |
1976年 | 28篇 |
1975年 | 20篇 |
1974年 | 22篇 |
1973年 | 22篇 |
1972年 | 14篇 |
排序方式: 共有1884条查询结果,搜索用时 0 毫秒
131.
Brown AR Bickley LK Le Page G Hosken DJ Paull GC Hamilton PB Owen SF Robinson J Sharpe AD Tyler CR 《Environmental science & technology》2011,45(9):4166-4172
Laboratory animals tend to be more inbred and less genetically diverse than wild populations, and thus may differ in their susceptibility to chemical stressors. We tested this hypothesis by comparing the responses of related inbred (theoretical inbreeding F(IT) = n + 0.25) and outbred (F(IT) = n) zebrafish (Danio rerio) WIK/Wild family lines to an endocrine disrupting chemical, clotrimazole. Exposure of inbred and outbred zebrafish to 2.9 μg clotrimazole/L had no effect on survival, growth, or gonadal development. Exposure of both lines to 43.7 μg clotrimazole/L led to male-biased sex ratios compared with controls (87% versus 55% and 92% vs 64%, for inbred and outbred males, respectively), advanced germ cell development, and reduced plasma 11-ketotestosterone concentrations in males. However, outbred males (but not inbred males) developed testis that were more than twice the weight of controls, which corresponded with a proliferation of Leydig cells and maintenance of the expression (rather than down-regulation occurring in inbreds) of gonadal aromatase (cyp19a1a) and insulin-like growth factor (igf1). Our results illustrate that the effects of an endocrine disrupting chemical (clotrimazole) on some end points (here testis development) can differ between inbred and outbred zebrafish. This highlights the need for reporting pedigree/genetic information and consistency in the responses of laboratory animals (e.g., by using model compounds as positive controls). 相似文献
132.
Primary Li-air cell development 总被引:1,自引:0,他引:1
Owen Crowther Benjamin MeyerMichael Morgan Mark Salomon 《Journal of power sources》2011,196(3):1498-1502
In the present communication, we report on recent researches for optimizing the performance of a primary organic-based Li-air cell. These researches focus on new processing technologies for a high capacity and high rate capable carbon cathode, and the development of oxygen selective membranes based on polysiloxane and methacrylate-polysiloxane copolymers. These membranes, generally classified as silicone rubbers exhibit high permeability for oxygen and impede water transport from the atmosphere into the Li-air cell and solvent loss from the cell into the atmosphere. 相似文献
133.
134.
Rositi Hugo Appadoo Owen Kevin Mestre Daniel Valarier Sylvie Ombret Marie-Claire Gadea-Deschamps Émilie Barret-Grimault Christine Lohou Christophe 《Multimedia Tools and Applications》2021,80(2):1945-1967
Multimedia Tools and Applications - Microsoft has recently released a mixed reality headset called HoloLens. This semi-transparent visor headset allows the user who wears it to view the projection... 相似文献
135.
David S. Owen 《Microscopy research and technique》2023,86(1):84-96
Approximations of the geometry of indenting probes, particularly when using shallow indentations on soft materials, can lead to the erroneous reporting of mechanical data in atomic force microscopy (AFM). Scanning electron microscopy (SEM) identified a marked change in geometry toward the tip apex where the conical probe assumes a near linear flat-punch geometry. Polydimethylsiloxane (PDMS) is a ubiquitous elastomer within the materials and biological sciences. Its elastic modulus is widely characterized but the data are dispersed and can display orders of magnitude disparity. Herein, we compare the moduli gathered from a range of analytical techniques and relate these to the molecular architecture identified with AFM. We present a simple method that considers sub-100 nm indentations of PDMS using the Hertz and Sneddon contact mechanics models, and how this could be used to improve the output of shallow indentations on similarly soft materials, such as polymers or cells. 相似文献
136.
Thermal Isolation of Encapsulated MEMS Resonators 总被引:1,自引:0,他引:1
Jha C.M. Hopcroft M.A. Chandorkar S.A. Salvia J.C. Agarwal M. Candler R.N. Melamud R. Bongsang Kim Kenny T.W. 《Journal of microelectromechanical systems》2008,17(1):175-184
This paper presents an in-chip thermal-isolation technique for a micro-ovenized microelectromechanical-system resonator. Resonators with a microoven can be used for high-precision feedback control of temperature to compensate for the temperature dependence of resonator frequency over a wide temperature range. However, ovenization requires power consumption for heating, and the thermal time constant must be minimized for effective temperature control. This paper demonstrates an efficient local-thermal-isolation mechanism, which can reduce the power requirement to a few milliwatts and the thermal time constant to a few milliseconds. In this method, the mechanical suspension of the resonator is modified to provide thermal isolation and include an integrated resistive heater. This combination provides mechanical suspension, electrical heating, and thermal isolation in a compact structure that requires low heating power and has a small thermal time constant. A power consumption of approximately 12 mW for a 125degC temperature rise and a thermal time constant ranging from 7 to 10 ms is reported in this paper, which is orders of magnitude lower than that of commercially available ovenized quartz resonators. A CMOS-compatible wafer-scale encapsulation process is used to fabricate this device, and the thermal-isolation design is achieved without any modification to the existing resonator fabrication process. 相似文献
137.
Over the past five years, practicum experience has received increased attention as an important element in the sequence of training. Questions have arisen about the number of hours being counted and the activities occurring in practicum. This study examined the number of practicum hours accrued by comparing the actual number of direct service hours and total hours to an estimated length of time to complete those hours. Based on self-reports, it was estimated that graduate students spend between 2 and 7 years to accrue their practicum hours with 37.5 to 69.6% of that time in direct service. Implications for the profession, faculty, and students are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
138.
A. J. Owen J. S. Colbourne C. R. I. Clayton C. Fife-Schaw 《Water and Environment Journal》1999,13(4):241-244
This study uses the psychological framework of 'mental modelling' to compare what experts and laypeople think about the hardness of drinking water. A drinking-water quality mental model was developed using influence-directed network procedures. This was evaluated in qualitative studies in Oxfordshire and the findings revealed gaps in laypeople's knowledge about the water-supply process. 相似文献
139.
140.