首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   236篇
  免费   30篇
林业   6篇
农学   1篇
  16篇
综合类   68篇
农作物   1篇
水产渔业   7篇
畜牧兽医   161篇
园艺   3篇
植物保护   3篇
  2022年   4篇
  2021年   2篇
  2020年   5篇
  2019年   6篇
  2018年   5篇
  2017年   3篇
  2016年   12篇
  2015年   3篇
  2014年   8篇
  2013年   11篇
  2012年   4篇
  2011年   5篇
  2010年   5篇
  2009年   3篇
  2008年   5篇
  2007年   6篇
  2006年   8篇
  2005年   6篇
  2004年   9篇
  2003年   6篇
  2002年   7篇
  2000年   5篇
  1999年   3篇
  1998年   10篇
  1997年   3篇
  1996年   10篇
  1993年   5篇
  1992年   7篇
  1991年   5篇
  1990年   7篇
  1989年   2篇
  1988年   11篇
  1987年   5篇
  1986年   3篇
  1983年   3篇
  1981年   3篇
  1979年   2篇
  1975年   2篇
  1974年   2篇
  1972年   4篇
  1971年   2篇
  1970年   2篇
  1969年   4篇
  1968年   2篇
  1967年   3篇
  1938年   2篇
  1923年   2篇
  1921年   2篇
  1911年   2篇
  1910年   2篇
排序方式: 共有266条查询结果,搜索用时 31 毫秒
91.
92.
93.
A 6‐year‐old, male castrated, domestic shorthair cat presented with a 2‐week history of blindness following general anesthesia. Behavioral changes, lethargy, inappetence and neurological deficits were also noted. Ophthalmic evaluation revealed blindness, normal pupillary light response and dazzle response, but no other abnormalities. Serodiagnostic testing for common infectious agents was negative and a cerebrospinal fluid analysis was normal. History and postmortem examination following euthanasia revealed cerebrocortical necrosis most consistent with anesthesia related hypoxia.  相似文献   
94.
95.
96.
Conservation tillage systems, including ridge‐tillage, have become increasing popular with producers in the central Great Plains because of their effectiveness in controlling soil erosion and conserving water. A major disadvantage of the ridge system is that nutrient placement options are limited by lack of any primary tillage options. The objective of this research was to investigate the effects of method of phosphorus (P) placement and rate on irrigated grain sorghum [Sorghum bicolor (L.) Moench] grown in a ridge‐tillage system on a soil low in available P. This experiment was conducted from 1993 to 1995 on a producer's field near the North Central Kansas Experiment Field at Scandia, Kansas on a Carr sandy loam soil (course, loamy, mixed, calcareous, mesic, Typic Udifuvents). Treatments consisted of fertilizer application methods, surface broadcast, single band starter (5 cm to the side and 5 cm below seed), dual band starter (one band on each side of the row), and knifed in the center of the row middle (38 cm from each adjacent row). Each of these treatments was made at either 22 or 44 kg P2O5 ha‐1, and nitrogen (N) also was included at the rate of 13 kg ha‐1. Additional treatments were, a combination of 13 kg N and 44 kg P2O5 ha‐1 applied half broadcast and half as a single band starter, a 1:1 N:P2O5 ratio (44 kg N and 44 kg P2O5 ha‐1) applied as a single band starter, and a 3:1 ratio (134 kg N and 44 kg P2O5 ha‐1) applied as a single band starter. A no‐P check plot also was included. Broadcast and center‐of‐row middle knife applications were made approximately 1 week before planting. After planting, N was balanced on all plots to give a total of 180 kg ha‐1. Applied P treatments improved grain yield and nutrient uptake and consistently shortened the time from emergence to mid‐bloom in all 3 years of the experiment. On this low soil test P soil, treatments that subsurface banded P increased grain yield by 1.27 Mg ha‐1 compared to broadcast treatments. Placing N and P in a single starter band 5 cm to the side and 5 cm below the seed was as effective as placing a band on each side of the row. Knife applying N and P in the center of the row was not as effective as placement beside the row. Single band starter application of N and P in a 1:1 and or 3:1 N:P2O5 ratio consistently increased yields and nutrient uptake and shortened the time to mid‐bloom as compared to the single band starter treatment that provided only 13 kg N ha‐1. Over the 3 years of the study, these 1:1 and 3:1 N:P2O5 ratio starters were clearly superior to an other treatments.  相似文献   
97.
98.
99.
A growth performance and carcass evaluation study was conducted to determine the maximal inclusion rate of corn distillers dried grain with solubles (DDGS) in grower-finisher pig diets when formulated on a total AA basis. A total of 240 (28.4 +/- 0.8 kg of BW) crossbred pigs [(Yorkshire x Landrace) x Duroc] were allotted randomly within sex and weight outcome groups to 1 of 24 pens. Pens were assigned randomly within the initial BW groups to 1 of 4 dietary treatment sequences in a 5-phase grower-finisher feeding program in a 4 x 3 factorial arrangement of treatments. The inclusion level of DDGS (0, 10, 20, or 30%) in the diet and the initial BW class [low (23.2 kg), medium (28.1 kg), or high (33.8 kg)] served as the main factors for the grower-finisher performance study. All diets were formulated to contain similar concentrations of total Lys, ME, calcium, and phosphorus within each phase. Pigs were slaughtered and carcass data were collected when the average BW of pigs in a pen reached 114 +/- 2.25 kg. Dietary treatment and initial weight groups did not interact for any response variables, and only the main effects of dietary treatment are presented. Pigs fed the 20 or 30% DDGS diets had reduced ADG (P < 0.05) compared with that of the 0 or 10% DDGS groups, but ADFI was unaffected by dietary treatment. Gain:feed decreased when pigs were fed 30% DDGS (P < 0.05) compared with the 0, 10, and 20% DDGS dietary inclusion levels. Loin depth was lower in pigs fed the 30% DDGS diets (P < 0.05), but backfat depth and percentage of carcass lean did not differ among treatments. Iodine number of carcass fat increased linearly (P < 0.01) with increasing dietary DDGS concentration, and belly firmness adjusted for belly thickness was reduced (P < 0.05) for pigs fed the 30% DDGS diets compared with pigs fed the 0 or 20% DDGS diets. Color measurements, ultimate pH, and visual evaluations (color, firmness, and marbling scores) of the LM did not differ among treatments. Cooking loss, 24-h drip loss, and total moisture loss were not affected by DDGS in the diets. However, differences were detected between 0 and 20% DDGS treatments for 11-d purge loss (P < 0.05). Dietary treatment did not affect Warner-Bratzler shear force of cooked loin chops. Results from this study indicate that when diets for grower-finisher pigs are formulated on a total AA basis, less than 20% DDGS should be included in the diet for optimal performance and carcass composition. Feeding DDGS in swine finishing diets did not have any detrimental effects on pork muscle quality.  相似文献   
100.
An experiment was conducted to determine if dietary inclusion of distillers dried grains with solubles (DDGS), soybean hulls, or soybean hulls sprayed with an egg-based, polyclonal antibody product would reduce the incidence or severity of infection, or both, in growing pigs after a Lawsonia intracellularis challenge. One hundred 17-d-old weaned pigs were blocked by sex, ancestry, and BW, and randomly allotted to 1 of 5 treatment groups: negative control, unchallenged, corn-soy diet; positive control, challenged, corn-soy diet; 20% DDGS diet (D), challenged; 5% soybean hulls diet (SH), challenged; and SH sprayed with a polyclonal antibody product diet, challenged. Challenged pigs were orally inoculated with 6.4 x 10(8) L. intracellularis organisms after a 4-wk prechallenge feeding period. On d 21 postchallenge, pigs were euthanized, lesions of intestinal mucosa were evaluated, and ileal tissue samples were analyzed by immunohistochemistry to determine the presence and proliferation rate of L. intracellularis. Challenging pigs with L. intracellularis reduced growth rate, feed intake, and efficiency of gain (P < 0.02) and increased the proportion of internal organ weights relative to BW (P < 0.01). Dietary treatment did not affect growth performance pre- or postchallenge (P > 0.10). Heart, empty stomach, and liver weights were similar among dietary treatments (P > 0.10). Weight of the large intestine as a percentage of BW was increased in D and SH pigs compared with positive control pigs (P < 0.05). Lesion length, prevalence, and severity, and fecal shedding of L. intracellularis were primarily unaffected by dietary treatment (P > 0.10), although ileal lesion length and severity observed tended to be greater in the SH sprayed with polyclonal antibody product diet vs. the D pigs (P < 0.10). Results from a previous study indicated that diet composition may affect length, severity, and prevalence of lesions caused by L. intracellularis in growing pigs subjected to a moderate challenge. However, beneficial results were not observed by feeding the dietary treatments used in this study.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号