全文获取类型
收费全文 | 328篇 |
免费 | 5篇 |
学科分类
工业技术 | 333篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 27篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 13篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 7篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有333条查询结果,搜索用时 375 毫秒
61.
Mould incidence and mycotoxin contamination in freshly harvested maize kernels originated from India
62.
Vijay I. P. Batra Hukam C. Bansal Shanti L. Mehta 《Journal of the science of food and agriculture》1982,33(1):30-34
Barley variety NP 113 had higher accumulations of dry matter (DM) and starch than its high-lysine mutant, Notch-2, during grain development. Protein, amylose and amylopectin content per grain were lower in Notch-2 than NP 113. Reducing sugars, free glucose, total fructose and non-reducing sugars were 1.57–3.15-fold in Notch-2 grain as compared with NP 113 grain. DM, protein, starch, amylose and amylopectin per grain increased during grain development. Soluble sugar contents per grain were maximum at 24 days after anthesis. Lower DM accumulation in the Notch-2 mutant as compared with its parent, NP 113, is due to lower starch deposition. Further, the limitation of starch synthesis in the Notch-2 mutant is not due to any limitation in the supply of soluble sugar precursors. 相似文献
63.
T R Batra C Y Lin A J McAllister A J Lee G L Roy J A Vesely J M Wauthy K A Winter 《Journal of dairy science》1987,70(10):2105-2111
Weekly milk yields of 1022 Holstein heifers from 61 sires were used to derive coefficients of the lactation curves using modified gamma and inverse polynomial functions. The natural logarithm of a modified gamma function was ln(yn) = ln (a) + b ln (n) + cn + u sin (x) + v cos (x), where a, b, c, u, and v are coefficients to be estimated; n is the day of lactation; and x is the day of year. Estimates of a, b, and c were combined to define persistency [-(b + 1) ln c], week of peak yield (b/c), and peak yield [a(b/c)be-b]. The inverse polynomial function was n/yn = A0 + A1n + A2n2, where A0, A1, and A2 are coefficients to be estimated. Variance and covariance components for the coefficients of the lactation curve were estimated by the multitrait restricted maximum likelihood method using canonical transformation. Heritability estimates were ln (a) .11, b .07, c .04 u .01, v .04, A0 .28, A1 .26, A2 .21, persistency .21, week of peak .18, peak yield .23, and 308-d milk yield .41. Genetic correlations indicated that selection for faster rate of increase to peak production would result in higher 308-d milk production, higher peak yield, and greater persistency. 相似文献
64.
Evaluating copper lysine and copper sulfate sources for heifers 总被引:2,自引:0,他引:2
Rabiansky PA McDowell LR Velasquez-Pereira J Wilkinson NS Percival SS Martin FG Bates DB Johnson AB Batra TR Salgado-Madriz E 《Journal of dairy science》1999,82(12):2642-2650
The effects of feeding different sources and quantities of Cu to heifers were evaluated in a 211-d experiment. Forty crossbred predominantly Brahman x Hereford heifers averaging 13.5 mo of age and 301 kg were initially depleted of Cu. The depletion diet was fed for 70 d and consisted of low Cu and high antagonist minerals, Fe, S, and Mo at 1000 mg/kg, 0.5%, and 5 mg/kg (dry basis), respectively. On d 71, heifers continued to receive the antagonistic minerals and were allotted equally to five Cu treatments: 1) control, no additional Cu source; 2) 8 mg of Cu/kg from CuSO4; 3) 16 mg of Cu/kg from CuSO4; 4) 8 mg of Cu/kg from Cu lysine; and 5) 16 mg of Cu/kg from Cu lysine. When no notable change in concentration of Cu in the liver was observed, d 169, a second diet was formulated. The heifers were fed the same Cu treatments, but S and Mo were removed and Fe was lowered to 50 mg/kg. This diet was then fed for the final 42 d of the experiment. In addition to performance, concentrations of Cu, Fe, and Zn in the plasma and liver, plasma ceruloplasmin, hemoglobin, superoxide dismutase (SOD) activity of neutrophils and lymphocytes, and a cell mediated immune response (phytohemagglutinin-P, PHA) were measured. Heifers in this study had increased growth over time, but there were no treatment differences for growth and average daily gain. Liver and plasma Cu concentrations were not greatly influenced by different supplemental Cu sources. However, compared with other treatments, Cu lysine (16 mg/kg) increased liver Cu in cattle that were deficient and tended to increase plasma Cu in animals that were marginally deficient in Cu. Iron concentrations decreased over time in liver and plasma, but there was no difference in Fe and Zn concentrations in liver and plasma among treatments. Differences in ceruloplasmin and hemoglobin concentrations were significant over time but not among treatments. The SOD activity in neutrophils did not change over time, but SOD activity of lymphocytes increased over time. For the PHA immune response test, there was no effect of time or a time by treatment interaction. These data suggest that all Cu sources were available, but Cu at 16 mg/kg from Cu lysine was more beneficial than were other sources and particularly for heifers with low Cu status. 相似文献
65.
The problem of helical flow of a Sutterby model fluid has been analyzed numerically using a finite difference technique. Sutterby model fluid is one of the most important non-Newtonian fluids representing constitutive equations for high polymer aqueous solutions of CMC, HEC, and MC, and hence the problem is of practical significance. Computations have been made for the case when the inner cylinder rotates about the common axis with constant angular velocity and the outer cylinder is at rest, while a constant pressure gradient is acting on the axis of rotation. The dimensionless velocity profiles, volumetric flow rate, torque, and pressure distribution have been calculated for various values of the model parameters and the radius ratio. 相似文献
66.
A study of bending deformations of sandwich plates using a layerwise theory of laminated or sandwich plates is presented. The analysis is based on a wavelet collocation technique to produce highly accurate results. Numerical results for symmetric laminated composite and sandwich plates are presented and discussed. 相似文献
67.
Composites of pyroelectric ceramics and polymers are very important as their unique features and properties can be easily
tailored for various specific applications. Lithium tantalatum oxide (LiTaO3, LT), the pyroelectric ceramic powder has been incorporated into a polyvinylidene fluoride–trifluoroethylene [P(VDF–TrFE)
70/30 mol%] copolymer matrix to form 0–3 composites. The composite films were prepared using ‘solvent casting’ (SC) method
to disperse the ceramic powder homogeneously in the P(VDF–TrFE) copolymer matrix with various wt% of LT powder. In order to
derive high pyroelectric performance, the samples were poled. Electric properties, such as the dielectric constant, dielectric
loss, and pyroelectric coefficient, have been measured as a function of temperature and frequency. In addition, material figures-of-merit,
very important factors for assessing many sensor applications have also been calculated. The results show that the fabricated
lead free lithium tantalite: P(VDF–TrFE) composite materials have a good potential for pyroelectric infrared sensor applications. 相似文献
68.
69.
70.
OBJECTIVES: To define the incidence and severity of ovarian hyperstimulation syndrome (OHSS) occurring in oocyte donors. METHODS: Women (n = 149) aged 31.3 +/- 4.8 years (mean +/- S.D., range 21-41 years) participated as designated oocyte donors and underwent 400 consecutive cycles of controlled ovarian stimulation using human menopausal gonadotropin following pituitary downregulation with gonadotropin-releasing agonist. Patients were monitored by serial transvaginal ultrasound examinations and serum estradiol (E2) determinations. Oocytes (15.6 +/- 7.5 per aspiration; range 2-57) were harvested by ultrasound-directed transvaginal follicle aspiration 36 h following the intramuscular injection of human chorionic gonadotropin (hCG). Follow-up examination occurred 1 and 2 weeks post-aspiration. RESULTS: On the day of hCG injection E2 levels ranged from 512 to 13,502 pg/ml (mean 2902.7 +/- 1486.9 pg/ml). Over the next few weeks the degree of hyperstimulation in donors was staged: mild 65% (grade I, n = 98; grade II, n = 162); moderate 33.5% (grade III, n = 120; grade IV, n = 14); severe 1.5% (grade V, n = 6; grade VI, n = 0). Associated preaspiration E2 levels were: grade I, 1120 +/- 424 pg/ml; grade II, 2084 +/- 613 pg/ml; grade III, 3785 +/- 1713 pg/ml; grade IV, 5370 +/- 1264 pg/ml; grade V, 4286 +/- 1100 pg/ml. Worsening OHSS was associated with increasing levels of E2. There were no serious complications and hospitalization was not required. All symptoms resolved within 30 days of aspiration, disappearing by the time of the first menstrual flow in women of grade-III or lower stage. CONCLUSION: Although oocyte donors commonly experienced exaggerated levels of serum E2 they rarely (< 2%) developed severe OHSS. This may be attributable to their lack of embryo transfer which avoids exacerbating the illness. 相似文献