全文获取类型
收费全文 | 235篇 |
免费 | 9篇 |
专业分类
林业 | 4篇 |
18篇 | |
综合类 | 38篇 |
农作物 | 1篇 |
水产渔业 | 13篇 |
畜牧兽医 | 157篇 |
园艺 | 3篇 |
植物保护 | 10篇 |
出版年
2021年 | 9篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 9篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有244条查询结果,搜索用时 453 毫秒
11.
Kendall PE Auchtung TL Swanson KS Radcliff RP Lucy MC Drackley JK Dahl GE 《Journal of animal science》2003,81(6):1440-1446
Photoperiod manipulation, specifically a long-day photoperiod (LDPP), increases milk production in lactating cattle. We have previously reported that the galactopoietic effect of LDPP is associated with an increase in circulating IGF-I, which seems to occur independently of changes in concentrations of GH, IGFBP-2, and IGFBP-3. This study tested the hypothesis that LDPP increases the expression of GH receptor (GHR) 1A messenger RNA (mRNA) in the liver. Two groups of Holstein steer calves (98 +/- 4 d old) were maintained indoors and exposed to LDPP (16-h light: 8-h dark; n = 6) or short-day photoperiod (SDPP; 8-h light: 16-h dark; n = 6) for 60 d. Calves were individually fed a grain- and alfalfa-based diet. Jugular blood samples were collected weekly and via cannula at 15-min intervals for a 4-h period on d 1, 26, and 55 of the study to monitor pulsatile hormone secretion. Serum was harvested and assayed for IGF-I, prolactin (PRL), and GH using RIA. Liver biopsies were obtained at 3-wk intervals to quantify changes in hepatic IGF-I and GHR 1A mRNA using real-time PCR. Steer BW increased during the study but did not differ between treatments. No differences in ADG or total DMI were observed. Relative to SDPP, calves on LDPP had higher (P < 0.05) serum IGF-I concentrations. Concentrations of PRL increased (P < 0.01) in calves exposed to LDPP compared with calves exposed to SDPP. Differences (P < 0.05) in pulsatile GH secretion were also detected. Hepatic IGF-I and GHR 1A mRNA were positively correlated with circulating IGF-I concentrations, and although both increased with time, they were not affected by photoperiod treatment. These results confirm that LDPP increases circulating concentrations of IGF-I, but this occurs independently of changes in IGF-I synthesis and GHR 1A mRNA expression in the liver. Therefore, our hypothesis that LDPP increases the expression of GHR 1A mRNA in the bovine liver is rejected. 相似文献
12.
Pancreatic exocrine secretion in steers infused postruminally with casein and cornstarch 总被引:1,自引:0,他引:1
Richards CJ Swanson KC Paton SJ Harmon DL Huntington GB 《Journal of animal science》2003,81(4):1051-1056
Our objective was to evaluate the effect of postruminal protein infusion on pancreatic exocrine secretions. One Holstein, two crossbred, and five Angus steers (305 +/- 5 kg) with pancreatic pouch-duodenal reentrant cannulas and abomasal infusion catheters were used in a replicated 4 x 4 Latin square. All steers were abomasally infused with 1,050 g/d of raw cornstarch with treatments of 0, 60, 120, or 180 g/d of sodium casein suspended in water to yield 6,000 g/d of infusate daily. Steers were limit-fed (1.5 x NEm; 12 equal portions daily) a 90% corn silage, 10% supplement diet formulated to contain 12.5% CP. Periods consisted of 3 d of adaptation to infusion, 7 d of full infusion, 1 d of collection, and 7 d of rest. Pancreatic juice was collected in 30-min fractions continuously for 6 h. Total juice secreted and the pH of individual fractions were recorded, a 10% subsample was retained to form a composite sample, and remaining fluid was returned to the duodenum. Juice composite samples were stored (-30 degrees C) until analyzed for total protein and activities of alpha-amylase, trypsin, and chymotrypsin. Casein infusion linearly increased alpha-amylase concentration (182 to 271 units/mL; P < 0.02; 17.5 to 24.6 units/mg of protein; P < 0.03) and secretion rate (26,847 to 41,894 units/h; P < 0.01). Total juice secretion (155 g/h), pH of pancreatic juice (8.13), secretion rate of protein (1,536 mg/h), and concentration of protein (10.2 mg/mL) in pancreatic secretions were not affected (P > 0.05) by casein infusion. Similarly, casein infusion did not change 0.05) trypsin and chymotrypsin concentrations (1,379 and 349 units/L or 0.134 and 0.033 units/mg of protein, respectively) or secretion rates (206 and 52 units/h, respectively). Abomasal infusion of protein with starch stimulated a greater pancreatic secretion of alpha-amylase activity into the intestine than infusion of starch alone. 相似文献
13.
Lekcharoensuk C Osborne CA Lulich JP Pusoonthornthum R Kirk CA Ulrich LK Koehler LA Carpenter KA Swanson LL 《American journal of veterinary research》2002,63(3):330-337
OBJECTIVE: To identify factors in dry diets associated with the occurrence of calcium oxalate (CaOx) uroliths in dogs. ANIMALS: 600 dogs with CaOx uroliths and 898 dogs without urinary tract diseases. PROCEDURE: Univariate and multivariate logistic regression were performed. RESULTS: Compared with diets with the highest concentrations of sodium, dry diets with the lowest concentrations of sodium, phosphorus, calcium, chloride, protein, magnesium, or potassium were linearly associated with increased risk of CaOx urolith formation. Significant nonlinear associations between increased occurrence of CaOx uroliths and urine acidifying potential and low moisture content were observed. Significant nonlinear associations between decreased occurrence of CaOx uroliths and carbohydrate and fiber contents were observed. A significant association between the occurrence of CaOx uroliths and dietary fat was not observed. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dry diets formulated to contain high concentrations of protein, calcium, phosphorus, magnesium, sodium, potassium, and chloride may minimize formation of CaOx uroliths. In addition, comparison of risk and protective factors of various diet ingredients fed to dogs with CaOx uroliths suggests that although similar findings were observed in canned and dry formulations, in general, greater risk is associated with dry formulations. However, before these hypotheses about dietary modifications are adopted by food manufacturers, they must be investigated by use of appropriately designed clinical studies of dogs with CaOx urolithiasis. 相似文献
14.
Lekcharoensuk C Osborne CA Lulich JP Pusoonthornthum R Kirk CA Ulrich LK Koehler LA Carpenter KA Swanson LL 《American journal of veterinary research》2002,63(2):163-169
OBJECTIVE: To identify dietary factors in commercially available canned foods associated with the development of calcium oxalate (CaOx) uroliths in dogs. ANIMALS: 117 dogs with CaOx uroliths and 174 dogs without urinary tract disease. PROCEDURE: Case dogs were those that developed CaOx uroliths submitted to the Minnesota Urolith Center for quantitative analysis between 1990 and 1992 while fed a commercially available canned diet. Control dogs were those without urinary tract disease evaluated at the same veterinary hospital just prior to or immediately after each case dog. A content-validated multiple-choice questionnaire was mailed to each owner of case and control dogs with the permission of the primary care veterinarian. Univariate and multivariate logistic regressions for each dietary component were performed to test the hypothesis that a given factor was associated with CaOx urolith formation. RESULTS: Canned foods with the highest amount of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, or moisture were associated with a decreased risk of CaOx urolith formation, compared with diets with the lowest amounts. In contrast, canned diets with the highest amount of carbohydrate were associated with an increased risk of CaOx urolith formation. CONCLUSIONS AND CLINICAL RELEVANCE: Feeding canned diets formulated to contain high amounts of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, and moisture and a low amount of carbohydrate may minimize the risk of CaOx urolith formation in dogs. 相似文献
15.
16.
J R Dodam K T Kruse-Elliott D P Aucoin C R Swanson 《American journal of veterinary research》1990,51(5):786-788
Plasma cortisol concentrations were compared in canine surgical patients given etomidate (2 mg/kg of body weight, IV) or thiopental sodium (12 mg/kg, IV) for anesthetic induction. Blood samples to determine plasma concentrations of etomidate were obtained at 0, 5, 10, 15, and 30 minutes and 1, 2, 3, 4, 5, 6, 8, 12, and 24 hours after induction. Adrenocortical function was evaluated before surgery by use of adrenocorticotropic hormone stimulation tests. Dogs in both induction groups had high plasma cortisol concentrations after induction. Dogs given thiopental had a significant increase (P less than 0.05) in plasma cortisol concentration from baseline at 2, 3, 4, 5, 6, 8, and 12 hours after induction. Dogs given etomidate had a significant increase (P less than 0.05) in plasma cortisol concentration from baseline at 5, 6, and 8 hours after induction. A comparison of plasma cortisol concentrations determined at 2, 3, 4, 5, and 6 hours after induction with thiopental or etomidate revealed a higher (P less than 0.05) concentration in dogs given thiopental. The disposition of etomidate was best described by a 2-compartment model, with a redistribution half-life of 0.12 +/- 0.04 minute and a terminal half-life of 1.70 +/- 0.27 minute. Plasma cortisol concentrations did not correlate with plasma etomidate concentrations. We conclude that, compared with thiopental, a single bolus injection of etomidate reduces the adrenocortical response to anesthesia and surgery from 2 to 6 hours after induction. Because cortisol concentrations were significantly higher than baseline, and because cardiopulmonary function is maintained after a single bolus injection of etomidate, it can be considered a safe induction agent in dogs. 相似文献
17.
The duality of teleost gonadotropins 总被引:5,自引:0,他引:5
Hiroshi Kawauchi Kunimasa Suzuki Hiromichi Itoh Penny Swanson Nobuko Naito Yoshitaka Nagahama Masumi Nozaki Yasumitu Nakai Seiga Itoh 《Fish physiology and biochemistry》1989,7(1-6):29-38
The duality of salmon gonadotropins has been proved by biochemical, biological, and immunological characterization of two
chemically distinc gonadotropins. GTH I and GTH II were equipotent in stimulating estradiol production, whereas GTH II appears
to be more potent in stimulating maturational steroid synthesis. The ratio of plasma levels and pituitary contents of GTHs
and the secretory control by a GnRH suggest that GTH I is the predominant GTH during vitellogenesis and early stages of spermatogenesis
in salmonids, whereas GTH II is predominant at the time of spermiation and ovulation. GTH I and GTH II are found in distinctly
separate cells. In trout, GTH I is expressed first in ontogeny, whereas GTH II cells appear coincident with the onset of spermatogenesis
and vitellogenesis, and increase dramatically at the time of final reproductive maturation. Comparison of the amino acid sequences
of polypeptides and the base sequences of cDNA revealed that salmon GTH I β is more similar to bovine FSHβ than bovine LHβ
and salmon GTH II β shows higher homology to bovine LHβ than to bovine FSHβ. The existence of two pituitary gonadotropins
in teleosts as well as tetrapods suggests that the divergence of the GTH gene took place earlier than the time of divergence
of teleosts from the main line of evolution leading to tetrapods. 相似文献
18.
19.
T L Martin L V Swanson L H Appell K E Rowe F Stormshak 《Domestic animal endocrinology》1990,7(1):27-34
Two experiments were conducted to investigate the response of the bovine corpus luteum to surges of luteinizing hormone (LH) induced by natural gonadotropin-releasing hormone (GnRH) administered twice during the same estrous cycle. In experiment 1, eight mature beef cows, each cow serving as her own control, were injected intravenously (iv) with saline on days 2 and 8 of the cycle (day of estrus = day 0 of the cycle), then with 100 micrograms GnRH on days 2 and 8 of the subsequent cycle. Jugular blood samples were taken immediately prior to an injection and at 15, 30, 45, 60, 120 and 240 min postinjection, to quantitate changes in serum luteinizing hormone. Blood was also collected on alternate days after an injection until day 16 of the cycle, to characterize changes in serum progesterone concentrations. Although exogenous GnRH caused release of LH on days 2 and 8 of the cycle, the quantity of LH released was greater on day 8 (P less than .025). Serum levels of progesterone after treatment with GnRH on day 8 of the cycle did not differ significantly from those observed during the control cycles of the heifers. Because exposure of the bovine corpus luteum to excess LH, induced by GnRH early during the estrous cycle, causes attenuated progesterone secretion during the same cycle, these data suggest that a second surge of endogenous LH may ameliorate the suppressive effect of the initial release of LH on luteal function. Duration of the estrous cycle was not altered by treatment (control, 20.4 +/- .5 vs. treated, 20.4 +/- .4 days).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
20.
Selenium: biochemical role as a component of glutathione peroxidase 总被引:157,自引:0,他引:157
J T Rotruck A L Pope H E Ganther A B Swanson D G Hafeman W G Hoekstra 《Science (New York, N.Y.)》1973,179(73):588-590
When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H(2)O(2), added glutathione failed to protect the hemoglobin from oxidative damage. This occurred because the erythrocytes were practically devoid of glutathione-peroxidase activity. Extensively purified preparations of glutathione peroxidase contained a large part of the (75)Se of erythrocytes labeled in vivo. Many of the nutritional effects of selenium can be explained by its role in glutathione peroxidase. 相似文献