全文获取类型
收费全文 | 686篇 |
免费 | 24篇 |
国内免费 | 1篇 |
专业分类
化学工业 | 93篇 |
金属工艺 | 13篇 |
机械仪表 | 14篇 |
建筑科学 | 11篇 |
能源动力 | 5篇 |
轻工业 | 59篇 |
水利工程 | 2篇 |
无线电 | 17篇 |
一般工业技术 | 43篇 |
冶金工业 | 430篇 |
原子能技术 | 2篇 |
自动化技术 | 22篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 5篇 |
2015年 | 12篇 |
2014年 | 14篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 22篇 |
2010年 | 24篇 |
2009年 | 14篇 |
2008年 | 23篇 |
2007年 | 14篇 |
2006年 | 16篇 |
2005年 | 23篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 11篇 |
1998年 | 106篇 |
1997年 | 75篇 |
1996年 | 57篇 |
1995年 | 21篇 |
1994年 | 26篇 |
1993年 | 24篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 14篇 |
1976年 | 29篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1970年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有711条查询结果,搜索用时 31 毫秒
21.
JB Van Liew PJ Davis FB Davis LL Bernardis MR Deziel LN Marinucci D Kumar 《Canadian Metallurgical Quarterly》1993,48(5):B184-B190
We studied the relationships of plasma glucose, fructosamine, triglycerides, and cholesterol as a function of age, gender, and diet in barrier-raised Fischer 344 rats aged 5 to 26 months, fed a diet either ad libitum or restricted to 60% of the ad libitum caloric intake. The complex relationships of these plasma levels to age, gender, and diet led to the development of a model with age, diet, and sex as covariates. Overall, fasting plasma glucose concentrations were reduced by approximately 25% in rats on the restricted diet, compared to ad libitum-fed animals. There was a significant age-dependent decline in glucose levels in male animals, whereas in females there was an increase in plasma glucose with aging. Plasma fructosamine levels in calorie-restricted animals, overall, were reduced by 7% compared to levels in animals fed ad libitum. There was a significant positive correlation between plasma glucose and fructosamine levels. Mean plasma triglyceride content was decreased by 50% in calorie-restricted rats compared to ad libitum-fed animals. A significant decrease in triglyceride levels with increasing age was seen in male animals, and an increase with aging in females. There was a significant positive correlation between plasma glucose and triglyceride levels. Plasma cholesterol levels in calorie-restricted animals were reduced by 7% compared to levels in ad libitum-fed animals. An increase of cholesterol concentration with aging was significant in both males and females. Analysis of the data showed that there were significant differences between male and female Fischer 344 rats in the response of plasma glucose and fructosamine to aging and calorie restriction. Changes of plasma triglyceride and cholesterol with aging and dietary calorie restriction were also different in males and females. Studies of the effect of aging on glycemia and blood lipid content should take into account the contributions of animal sex. 相似文献
22.
23.
1. Several ring-substituted derivatives of diphenyleneiodonium catalyse the exchange of Cl- and OH- ions across the inner membrane of rat liver mitochondria. They also inhibit state 3 and state 3u oxidations of glutamate plus malate in the presence of Cl- more than in its absence. Most have activities similar to diphenyleneiodonium, although 2,4-dichlorodiphenyleneiodonium is up to 50 times more active. 2. Diphenyleneiodonium inhibits soluble rat liver NADH dehydrogenase and NADH oxidation by rat liver sub-mitochondrial particles directly; 2,4-dichlorodiphenyleneiodonium is only about twice as inhibitory. 3. Liver mitochondria contain two classes of binding sites for diphenylene[125I]iodonium, namely high-affinity sites with an affinity constant of 3 X 10(5) M-1 (1--2 nmol/mg of protein), and low-affinity sites with an affinity constant of 1.3 X 10(3) M-1 (80 nmol/mg of protein). Both sites occur in hepatocytes with a relative enrichment of the low-affinity site. Nadh dehydrogenase preparations only apparently contain high-affinity binding sites. Only low-affinity sites occur in erythrocytes. 4. 2,4-Dichlorodiphenyleneiodonium competes with diphenylene[125I]iodonium for both low- and high-affinity sites, whereas tri-n-propyltin only competes for the low-affinity sites. 5. The high-affinity sites are apparently associated with NADH dehydrogenase and the low-affinity sites probably represent electrostatic binding of diphenylene[125I]iodonium to phospholipids. The high-affinity site does not appear to be associated with a rate-limiting stage of NADH oxidation. 相似文献
24.
Yoganathan S Nicolosi R Wilson T Handelman G Scollin P Tao R Binford P Orthoefer F 《Lipids》2003,38(6):603-607
Emu oil is derived from the emu (Dromaius novaehollandiae), which originated in Australia, and has been reported to have anti-inflammatory properties. Inflammation was induced in
anesthetized CD-1 mice by applying 50 μL of 2% croton oil to the inner surface of the left ear. After 2 h, the area was treated
with 5μL of emu, fish, flaxseed, olive, or liquified chicken fat, or left untreated. Animals were euthanized at 6 h postapplication
of different oils, and earplugs (FP) and plasma samples were collected. Inflammation was evaluated by change in earlobe thickness,
increase in weight of EP tissue (compared to the untreated ear), and induction in cytokines interleukin (IL)-1α and tumor
necrosis factor-α (TNF-α) in EP homogenates. Al-though reductions relative to control (croton oil) were noted for all treatments,
auricular thickness and EP weights were, significantly reduced (−72 and −71%, respectively) only in the emu oil-treated group.
IL-1α levels in homogenates of auricular tissue were significantly reduced in the fish oil (−57%) and emu oil (−70%) groups
relative to the control group. The cytokine TNF-α from auricular homogenates was significantly reduced in the olive oil (−52%)
and emu oil (−60%) treatment groups relative to the control group. Plasma cytokine levels were not changed by croton oil treatment.
Although auricular thickness and weight were significantly correlated with each other (r=0.750, P<0.003), auricular thickness but not weight was significantly correlated with cytokine IL-1α (r=0.750, P<0.006) and TNF-α (r=0.690, P<0.02). These studies indicate that topical emu oil has anti-inflammatory properties in the CD-1 mouse that are associated
with decreased auricular thickness and weight, and with the cytokines IL-1α and TNF-α. 相似文献
25.
M. Modreanu M. Nolan O. Durand G. Garry G. Huyberechts M. Androulidaki 《Thin solid films》2007,515(24):8624-8631
In this paper, we report first principles calculations and experimental studies of the optical and microstructural properties of both bulk and thin films of SrCu2O2. Polycrystalline SrCu2O2 films were grown by a conventional Pulsed Laser Deposition method in a flowing oxygen environment on corning glass 7059 and silicon substrates. Several characterization techniques, including X-ray diffraction (XRD), Fourier Transform IR (FTIR), Raman, spectroscopic ellipsometry, reflectance/transmission spectrophotometry and Atomic Force Microscopy have been used for the investigation of the microstructural and vibrational properties of both bulk and thin films of SrCu2O2.XRD shows that bulk SrCu2O2 is polycrystalline and assumes the pure tetragonal phase of SrCu2O2. The vibrational properties of the tetragonal phase of SrCu2O2 have been inferred from Raman and FTIR spectroscopies and for the first time both Raman and IR active modes have been assigned. The bulk polycrystalline SrCu2O2 optical band gap determined from spectroscopic ellipsometry was 3.34 ± 0.01 eV. XRD results confirmed that pure non-textured polycrystalline phase SrCu2O2 thin films with a smooth surface can be grown by PLD at low temperature (300 °C). 相似文献
26.
27.
Juan M. Garcés Michael M. Olken G. John Lee Garry R. Meima Pierre A. Jacobs Johan A. Martens 《Topics in Catalysis》2009,52(9):1175-1181
This is a review of work carried at Dow Chemical on the design and characterization of novel mordenite catalysts with a unique
micro and meso-porous structure characterized by a variety of methods including, TEM, BET surface area and pore size distribution,
and n-decane hydro-conversion. The catalytic performance of these catalysts in shape selective reactions is illustrated with results
from n-decane hydro-conversion and applications to alkylation and trans-alkylation reactions of mono and polynuclear aromatic hydrocarbons and other chemistries.
Juan M. Garcés and G. John Lee both retired from The Dow Chemical Company. 相似文献
28.
29.
30.
KL Cheung PC Willsher JF Robertson FB Bailie JC Daly RW Blamey 《Canadian Metallurgical Quarterly》1997,67(4):185-186
A randomized double-blind controlled trial was undertaken to study the efficacy of a cow udder ointment versus petroalatum alone. A total of 30 patients participated in the study. Sixteen patients completed the trial with 8 of 9 patients improving in the active group and 6 of 7 patients improving in the placebo group. This difference was not statistically significant. The use of a cow udder ointment for psoriasis cannot be supported, particularly with the potential for side effects. 相似文献