全文获取类型
收费全文 | 4068篇 |
免费 | 43篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 6篇 |
综合类 | 6篇 |
化学工业 | 221篇 |
金属工艺 | 33篇 |
机械仪表 | 34篇 |
建筑科学 | 32篇 |
能源动力 | 49篇 |
轻工业 | 132篇 |
水利工程 | 7篇 |
石油天然气 | 6篇 |
无线电 | 104篇 |
一般工业技术 | 289篇 |
冶金工业 | 3078篇 |
原子能技术 | 11篇 |
自动化技术 | 105篇 |
出版年
2023年 | 14篇 |
2021年 | 22篇 |
2020年 | 15篇 |
2019年 | 18篇 |
2018年 | 30篇 |
2017年 | 17篇 |
2016年 | 22篇 |
2015年 | 23篇 |
2014年 | 25篇 |
2013年 | 85篇 |
2012年 | 30篇 |
2011年 | 38篇 |
2010年 | 30篇 |
2009年 | 28篇 |
2008年 | 44篇 |
2007年 | 45篇 |
2006年 | 38篇 |
2005年 | 30篇 |
2004年 | 34篇 |
2003年 | 42篇 |
2002年 | 36篇 |
2001年 | 30篇 |
2000年 | 17篇 |
1999年 | 140篇 |
1998年 | 1000篇 |
1997年 | 579篇 |
1996年 | 383篇 |
1995年 | 209篇 |
1994年 | 159篇 |
1993年 | 202篇 |
1992年 | 27篇 |
1991年 | 37篇 |
1990年 | 38篇 |
1989年 | 52篇 |
1988年 | 36篇 |
1987年 | 41篇 |
1986年 | 32篇 |
1985年 | 46篇 |
1983年 | 13篇 |
1982年 | 23篇 |
1981年 | 23篇 |
1980年 | 40篇 |
1979年 | 13篇 |
1978年 | 18篇 |
1977年 | 61篇 |
1976年 | 126篇 |
1975年 | 18篇 |
1973年 | 10篇 |
1972年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有4113条查询结果,搜索用时 15 毫秒
1.
JE Myers T Mieczkowski J Perel D Abbondanza TB Cooper JJ Mann 《Canadian Metallurgical Quarterly》1994,35(2):112-120
Serotonergic responsivity was assessed in 20 psychiatric patients by the prolactin response to a fenfluramine challenge test. During the fenfluramine challenge 6 of 20 patients (30%) spontaneously reported psychopathologic reactions that included: increased anxiety/agitation, psychotic symptoms, illusions, mood elevation, and anergia. The time of peak behavioral symptoms (2.5 +/- 0.8 hrs) corresponded closely to the time of peak increase in prolactin levels (3.0 +/- 1.1 hr). Abnormal behavioral responders had statistically significant greater increases in prolactin 1 to 4 hr after fenfluramine when compared to normal responders. Patients who developed an abnormal psychopathologic response to fenfluramine were characterized by higher levels of anxiety and agitation at the time of admission to the hospital but otherwise were not distinguishable on the basis of severity of other psychiatric symptoms. This study suggests that increased serotonergic transmission may trigger anxiety, psychosis, and mood elevation in specific vulnerable individuals, whereas other patients with similar psychiatric illnesses are not affected. 相似文献
2.
3.
4.
This report analyzes the intracorporal lengths of 236 consecutive organically impotent men who underwent insertion of a penile prosthesis. The average right or left intracorporal length in this series was 20.9 cm, with a standard deviation of 2.2 cm. Intracorporal length ranged from 14-27 cm. This data may be used as reference ranges for penile prosthesis manufacturers, and for Urologists who implant prostheses or perform penile lengthening procedures. 相似文献
5.
Recent research has found that family caregivers do not discuss their caregiving in terms of tasks but instead describe their care as shaped by concerns, commitments and goals. The purpose of this paper is to challenge the ways in which nurses approach the family caregiving process and to explore possibilities for evolving nursing knowledge by questioning existing practice in the light of developing insight into the ways in which being a family caregiver is meaningful. A critique of the philosophical orientations of rationalism and empiricism provides a platform to discuss the merits of a Heideggerian phenomenological approach in assisting nurses to better understand family caring experience. Such critique serves to support the notion of displacing the traditional scientific view as the prime means of disclosing truth, acknowledging alternative ways of knowing. 相似文献
6.
7.
E J Mann 《International Journal of Dairy Technology》2004,57(4):244-244
8.
Higher heating values (HHVs) of fatty acids (C4–C18) were measured and correlated using linear least square regression analysis. Equations were developed for the estimation of the HHVs of saturated fatty acids from their molecular weight (Mw), density (DN) and carbon number (CN). These equations are HHV = 0.0518 Mw + 29.76, HHV = −93.4 DN + 122.67 and HHV = 0.7271 CN + 31.419 with R2 values of 0.9895, 0.9798, and 0.9895, respectively. The correlations may be used for HHV estimation of mixtures of fatty acids developed from vegetable oils. 相似文献
9.
In this work, we co‐formulated an oil‐borne copper naphthenate/permethrin wood preservative system with synthetic polymer‐based fire‐retardant additives prior to the impregnation of Pinus radiata sapwood. We evaluated what effect, if any, the preservative had upon the fire performance properties of the fire retardants and whether the fire retardants impacted on the fungicidal and termiticidal efficacy of the preservative. The fire retardants included halogenated and phosphorus‐based systems. A mass loss calorimeter, in conjunction with a thermopile, was used to measure the time to ignition and the peak heat release rate (PHRR) from which the fire performance index (FPI) was determined. The preservative properties were evaluated using termite and soil‐block decay bioassays. In summary, we found that the rate of fire growth was reduced when the fire retardants were used in combination with the wood preservative. We also found that the PHRR was a better determinant of fire performance than the FPI. The performance of the wood preservative was enhanced against fungal decay and termite attack when used in combination with the fire retardants. The fire retardants also demonstrated some wood preservative properties of their own. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
10.
SL Nyberg HJ Mann MY Hu WD Payne WS Hu FB Cerra RP Remmel 《Canadian Metallurgical Quarterly》1996,24(6):643-648
OBJECTIVE: The initially well-fixed implants of total hip replacement (THR) are in the long-term subject to aseptic loosening. Many cytokines can contribute to osteolysis due to osteoclast recruitment and/or activation. However, in this respect tumor necrosis factor-alpha (TNF-alpha) plays a pivotal role, because it upregulates interleukin-1 and 6 and granulocyte-macrophage colony stimulating factor. The aim of this study was to assess the eventual presence, cellular localization and extent of expression of TNF-alpha in the synovial-like membrane at the implant or at the cement to bone interface compared to control synovial membrane. METHODS: Twenty samples from the synovial-like membrane of the periprosthetic tissues were compared to control samples. TNF-alpha containing cells were visualized using an avidin-biotin-peroxidase complex (ABC) method and analyzed by light microscopy, double labelling and image analysis. RESULTS: TNF-alpha was found in the periprosthetic tissues in fibroblasts and vascular endothelial cells, but mainly in the macrophages was it found to coincide with areas containing implant-derived debris. TNF-alpha containing cells were more numerous in the synovial-like membrane in the interface tissue from the proximal stem area (2816 +/- 318 cells) than in the control synovial membrane (565 +/- 93 cells, p < 0.01). Interestingly, similarly high TNF-alpha expression (3452 +/- 582 cells) was also seen in the synovial-like membrane of the pseudocapsule. CONCLUSION: These findings suggest that the foreign body-type host reaction caused by THR is characterized by the high expression of TNF-alpha. Because such expression occurred in the interface tissue between the implant and surrounding bone, TNF-alpha, due to its pivotal direct and indirect role in the activation and recruitment of osteoclasts, may contribute to periprosthetic osteolysis and to the loosening of THR. 相似文献