全文获取类型
收费全文 | 183篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
林业 | 2篇 |
农学 | 1篇 |
28篇 | |
综合类 | 21篇 |
水产渔业 | 2篇 |
畜牧兽医 | 131篇 |
园艺 | 1篇 |
植物保护 | 9篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 16篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 14篇 |
1997年 | 3篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1960年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有195条查询结果,搜索用时 15 毫秒
31.
A longitudinal study of veterinary students and recent graduates: 3. Perceptions of veterinary education 总被引:1,自引:1,他引:0
Objective To examine the attitudes and opinions on veterinary education at the beginning and end of the veterinary course, and after graduation.
Design Longitudinal study.
Population Students – 154 in all – who began studying veterinary science at The University of Queensland in 1985 and 1986.
Procedure Questionnaires were completed in the first and fifth year of the course and in the second year after graduation. The data were analysed using the SAS System for Windows.
Results When they entered the course, the students were looking forward more to learning about animals than about basic sciences. At fifth year and after graduation most believed that more emphasis should have been placed on all facets of their education except the basic sciences. It may be difficult to increase this emphasis without placing undue pressure on the students, although more than half of the fifth year students and graduates agreed that there is much in the curriculum that is not needed by a practising veterinarian. Only one-third or less agreed that veterinarians are well equipped to practise veterinary science immediately they graduate. There was no relationship between the level of agreement with this statement, and the academic grades obtained.
Conclusions A majority of veterinary graduates do not believe that they are well equipped to practice immediately they graduate. They believe that more emphasis should have been placed on most facets of their education, but, conversely, that there is much in the curriculum that is not needed by a practising veterinarian. 相似文献
Design Longitudinal study.
Population Students – 154 in all – who began studying veterinary science at The University of Queensland in 1985 and 1986.
Procedure Questionnaires were completed in the first and fifth year of the course and in the second year after graduation. The data were analysed using the SAS System for Windows.
Results When they entered the course, the students were looking forward more to learning about animals than about basic sciences. At fifth year and after graduation most believed that more emphasis should have been placed on all facets of their education except the basic sciences. It may be difficult to increase this emphasis without placing undue pressure on the students, although more than half of the fifth year students and graduates agreed that there is much in the curriculum that is not needed by a practising veterinarian. Only one-third or less agreed that veterinarians are well equipped to practise veterinary science immediately they graduate. There was no relationship between the level of agreement with this statement, and the academic grades obtained.
Conclusions A majority of veterinary graduates do not believe that they are well equipped to practice immediately they graduate. They believe that more emphasis should have been placed on most facets of their education, but, conversely, that there is much in the curriculum that is not needed by a practising veterinarian. 相似文献
32.
A ruminal fermentation trial and a steer growth trial were conducted to evaluate the effects of time interval of cottonseed meal (CSM) supplementation of predominantly meadow fescue grass hay (GH; CP = 6.6%) on nutrient digestion and growth performance of beef steers. The fermentation trial used four ruminally cannulated steers assigned to a 4 x 4 latin square design with dietary treatments of GH fed alone (C) or GH supplemented with 3 g CP/kg BW.75 daily as supplied by CSM every 12, 24 or 48 h. Nylon bags containing GH were inserted into the rumen on d 1 and 2 of each collection period and incubated for 12, 24, 48 and 96 h to measure NDF and ADF degradation. Subsequently, steers were fed Yb-labeled GH and fecal samples were collected to determine particulate passage rate (PR). Dry matter and NDF intake, mean NDF and ADF in situ disappearance and ruminal VFA concentrations were greater (P less than .05) when CSM was fed; however, the delivery of CSM at various times did not affect (P greater than .10) these variables. Supplemented diets tended (P = .08) to have faster PR compared with the C diet. In the growth trial, CSM supplemented steers consumed more digestible DM (P less than .05) and had greater (P less than .05) daily gain compared with C steers. Effects due to time of CSM supplementation were not observed for the variables measured in the present study. 相似文献
33.
34.
35.
36.
Evaluation of potential techniques for rejuvenating oak shoots requires robust quantitative markers for juvenile and mature plants. To identify suitable in vitro markers, shoot cultures of Quercus species of juvenile, adolescent and mature origin were screened for a range of morphological and physiological markers of juvenility and maturity. Criteria examined included angle of the shoot to the horizontal, stem length, stem diameter (tip, mid, base), leaf number, scale leaf number and shoot number. Image analysis was also carried out to determine leaf area, size, perimeter and breadth and length of leaves. Mature Q. robur L. clones had a larger mid-stem and tip diameter than juvenile clones, whereas mature Q. petraea ex Liebl. clones were characterized by plagiotropic growth and larger mid-stem and tip diameters compared with juvenile clones. Based on discriminant analysis of the data, we propose the following formulae for discrimination of juvenile and mature shoots, where a negative value for the discriminant score (D) indicates juvenility. For Q. petraea: D = -1.308 - 0.0351 SA + 2.206 TD + 1.435 MSD, where SA is stem angle ( degrees ), TD is tip diameter (mm) and MSD is mid-stem diameter (mm). For Q. robur: D = -3.546 + 2.418 TD + 2.202 MSD. Quercus robur clones derived from stump sprouts and designated as juvenile had a negative D value suggesting a juvenile status for these clones. Clones sourced from a hedged, grafted Q. robur tree of mature origin had a positive D value indicating a mature status. Clones initiated from a 20-25-year-old Q. petraea tree displayed morphology in vitro consistent with a mature status and had a positive D value; however, these clones displayed other traits such as vigor suggesting that vestiges of juvenility remain. Multiplication rate and leaf size and shape were variable among clones and did not provide suitable markers for juvenility or maturity for these Quercus species. 相似文献
37.
OBJECTIVE: To investigate what factors relate most strongly to breast-feeding duration in order to successfully support breast-feeding mothers. DESIGN: Prospective birth cohort study using questionnaires, routinely collected weights and health check at age 13 months. SETTING: Gateshead, UK. SUBJECTS: Parents of 923 term infants born in a defined geographical area and recruited shortly after birth, 50% of whom were breast-feeding initially. RESULTS: Only 225 (24%) infants were still breast-fed at 6 weeks, although 136 (15%) continued beyond 4 months. Infants in the most affluent quintile were three times more likely to be initially breast-fed (P < 0.001) and five times more likely to still be feeding at 4 months (P = 0.001) compared with infants in the most deprived quintile. A third of breast-fed infants were given supplementary feeds in the maternity unit and this was associated with a 10-fold increase in odds of giving up breast-feeding by discharge (P = 0.001). Frequent feeding was reported as a reason for giving up in 70% of mothers at 6 weeks and 55% at 4 months. Those infants who stopped breast-feeding earliest showed the most rapid weight gain and were tallest at age 13 months. Non-breast-fed infants had 50% more family doctor contacts up to age 4 months (P = 0.005). CONCLUSIONS: Initiation of breast-feeding in urban Britain remains strongly determined by socio-economic background and early cessation seems to be related to frequent feeding and rapid growth as well as a continuing failure to eradicate health practices that undermine breast-feeding. Those infants not receiving breast milk suffered increased morbidity, but the apparent association between breast-feeding duration and growth probably reflects reverse causation. 相似文献
38.
The workloads, study methods, and motivation of students in a five-year BVSc program were studied using questionnaires and focus groups. Students in each year of the program were asked, on three occasions over an academic year, to record details of their out-of-class study time for each course they were taking and to record the study methods they used, how they prioritized their time between subjects, and how they allocated time to study and leisure activities. Mean response rates were 57% (range: 43-85%). Overall mean out-of-class study time ranged from 19 hours per week in Year 2 to 28 hours per week in Year 4. Study time was related to the level of interest the student had in the subject, the demands of assessments, and the number of subjects being studied. Study methods were related to students' perceptions of the requirements of the subject as well as to their interest in it. Reliance on memorization and the use of set study materials were the predominant methods for courses with low interest scores, whereas higher interest was associated with a broad range of study methods. Leisure time was ring-fenced, especially when workloads were high. Students' motivation was high when they were studying subjects that were new or were seen as relevant to clinical practice; when working with animals or with enthusiastic faculty members; and when involved in subjects more tightly focused on the ultimate goal of becoming a practitioner. It was poor when students were faced with high workloads, disciplines becoming "stale," excessive detail, and low perceptions of relevance. Constant assessment activities were also seen as a burden. In terms of good learning practices, workload and the demands of assessment were considered to be antagonistic. A tension between these perceptions of students and the values of faculty in terms of the development of critical thinking skills in the program is evident. 相似文献
39.
HT Duong DJ Skarzynski KK Piotrowska‐Tomala MM Bah K Jankowska P Warmowski K Łukasik K Okuda TJ Acosta 《Reproduction in domestic animals》2012,47(6):939-945
Previous in vitro studies demonstrated that bovine endometrium has the capacity to convert inactive cortisone to biologically active cortisol (Cr) and that Cr inhibits cytokine‐stimulated prostaglandin F2α (PGF) production. This study was carried out to test the hypothesis that bovine reproductive tract has the capacity to convert cortisone to Cr in vivo and to evaluate the effects of intravaginal application of exogenous cortisone on uterine PGF secretion during the late luteal stage. The temporal relationships between PGF and Cr levels in uterine plasma were also determined. Catheters were inserted into jugular vein (JV), uterine vein (UV), vena cava caudalis (VCC) and aorta abdominalis (AA) of six cows on Day 15 of the oestrous cycle (ovulation = Day 0) for frequent blood collection. On Day 16, the cows were divided randomly into two groups and infused intravaginally with vaseline gel (10 ml; control; n = 3) or cortisone dissolved in vaseline gel (100 mg; n = 3). Blood samples were collected at ?2, ?1, ?0.5, 0, 0.5, 1, 1.5, 2, 3, 4, 5 and 6 h after treatments (0 h). Intravaginal application of cortisone increased plasma concentrations of Cr between 0.5 and 1.5 h in UV, at 0.5 h in VCC, at 1 h in JV and at 1.5 h in AA. The plasma concentrations of PGF in UV and of PGF metabolite in JV were greater at 0.5 and 1 h in the cortisone‐treated animals than in control animals. The levels of PGF in UV blood plasma decreased after Cr reached its highest levels. The overall findings suggest that the female reproductive tract has the capacity to convert cortisone to Cr in vivo. Based on the temporal changes of PGF and Cr levels in the uterine plasma, a biphasic response in PGF secretion was found to be associated to the Cr increase induced by the cortisone treatment at the late luteal stage in non‐pregnant cows. 相似文献
40.
B Behr D Rath TB Hildebrandt F Goeritz S Blottner TJ Portas BR Bryant B Sieg A Knieriem SP de Graaf WMC Maxwell R Hermes 《Reproduction in domestic animals》2009,44(2):273-277
Flow cytometric sexing of spermatozoa followed by application in artificial insemination or in vitro fertilization provides a unique opportunity to predetermine the sex of offspring and might enhance the conservation management of endangered species in captivity such as the elephant and rhinoceros. To obtain an indication of the sortability of spermatozoa from these species, the relative DNA differences between X and Y chromosome bearing spermatozoa (fresh, frozen thawed, epididymal) from three rhinoceros species [white ( Ceratotherium simum ), black ( Diceros bicornis ), Indian ( Rhinoceros unicornis )] and both elephant species, the Asian and the African elephant ( Elephas maximus, Loxodonta Africana ), were determined through separation of spermatozoa into X and Y chromosome bearing populations, using a modified high speed flow cytometer. The head profile areas of spermatozoa from all five species were measured using light microscopy. By multiplying the relative DNA differences and the head profile areas, the sperm sorting indices were calculated to be 47, 48 and 51 for white, black and Indian rhinoceros respectively. The calculated sorting index for the Asian elephant was 66. In the African elephant, we determined the highest sorting index of 76. These results indicate the practicability of flow cytometric sex sorting of spermatozoa from the tested rhinoceros species and both elephant species. The lower sorting indices in rhinos indicate that sex sorting of spermatozoa from the rhinoceros will be more challenging than in elephants. 相似文献