全文获取类型
收费全文 | 631篇 |
免费 | 78篇 |
专业分类
林业 | 40篇 |
农学 | 26篇 |
120篇 | |
综合类 | 17篇 |
农作物 | 39篇 |
水产渔业 | 93篇 |
畜牧兽医 | 294篇 |
园艺 | 10篇 |
植物保护 | 70篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 25篇 |
2021年 | 39篇 |
2020年 | 53篇 |
2019年 | 61篇 |
2018年 | 49篇 |
2017年 | 50篇 |
2016年 | 44篇 |
2015年 | 32篇 |
2014年 | 33篇 |
2013年 | 35篇 |
2012年 | 41篇 |
2011年 | 41篇 |
2010年 | 20篇 |
2009年 | 21篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1971年 | 3篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有709条查询结果,搜索用时 408 毫秒
21.
22.
Manuel Benlloch-Gonzalez Eymeric Gomes Bernard Bouvy Cyrill Poncet 《The Canadian veterinary journal. La revue veterinaire canadienne》2015,56(7):715-722
This prospective clinical study evaluated the use, complications, and clinical and ultrasonographic follow-ups of end-to-end intestinal anastomoses with skin staples in naturally occurring diseases in canine small and large intestines. Intestinal anastomoses were performed in 14 dogs and pre-, peri-, and postoperative data were recorded. Postoperative clinical and ultrasound evaluations were performed at regular intervals for 1 year. The mean time taken to construct the anastomosis was 5 min. There were no intraoperative complications. Hemorrhage and colonic stricture were the main postoperative complications. Staple loss occurred in 2 cases. Absence of wall layering and focal wall thickening were observed in all cases at each ultrasonographic follow-up. Hyperechoic fat was observed in all but 1 of the cases at month 1. Nine dogs were alive with normal digestive function at the end of the study. The skin stapler technique enabled rapid construction of consistent anastomoses with inexpensive stapling material. 相似文献
23.
Immunohistochemical Expression of Growth Factors in the Follicular Wall of Normal and Cystic Ovaries of Sows 下载免费PDF全文
FJF Sant'Ana JL Reis Junior GR Blume EJ Gimeno F Rey HH Ortega 《Reproduction in domestic animals》2015,50(2):327-332
The expression of growth factors was evaluated immunohistochemically in normal and cystic ovaries of sows. The immunohistochemically stained area (IHCSA) was quantified by image analysis to analyse the expression of these proteins in the follicular wall of secondary, tertiary and cystic follicles. IGF‐I immunoreactivity was strong in the granulosa cell layer (GC), moderate in the theca interna (TI) and mild in the theca externa (TE) of the normal follicles. There was severe reduction of the labelling to IGF‐I in the GC of the follicular and luteinized cysts. In the normal follicles, the reactivity for IGF‐II was very similar to pattern noted in IGF‐I. There was reduction of the IHCSAs in the GC of the follicular and luteinized cysts, but the decrease was not significant. The staining of the IGF‐II in the TI and TE of the cysts was increased, in comparison with normal follicles. The IHCSAs for VEGF were higher in the GC and TE of the normal follicles in contrast to TI, but this difference was noted only in the tertiary follicle. The VEGF reactivity increased in the GC of the cysts, in relation to normal follicles. The results of the current study show that the formation of ovarian cysts in sows is associated with alterations in the immunohistochemical expression of some growth factors. 相似文献
24.
de Andrade Thiago Cavalcante Gomes Ribeiro Bacha Allan Lopes de Camargo Mariane Bueno de Carvalho Leonardo Bianco 《New Forests》2022,53(1):143-160
New Forests - Previous studies have reported that phosphorus transporters are involved in glyphosate uptake by plants, so phosphorus fertilization might act as an attenuator of glyphosate effects... 相似文献
25.
AM Batista WA Gomes CCD Carvalho PLJ Monteiro Jr FLM Silva FC Almeida PC Soares GF Carneiro MMP Guerra 《Reproduction in domestic animals》2014,49(3):476-480
The aim of this study was to evaluate the effect of leptin administration during superovulation on in vivo goat embryo production. Ten mature does were superovulated with 133 mg follicle‐stimulating hormone (FSH) i.m. in six descending doses at 12‐h intervals. The goats received 4.8 μg/kg human recombinant leptin s.c. (leptin group, n = 5) or phosphate‐buffered saline (PBS) (control group, n = 5) with the first and second FSH doses. The does were mated and subjected to embryo collection by transcervical technique 6 days later. The total number of cells per embryo and the number of cells with fragmented DNA were assessed in selected blastocysts by combining Hoechst 33342 and terminal dUTP nick‐end labelling (TUNEL) staining. Plasma concentrations of oestradiol (E2) and progesterone (P4) were determined by electrochemiluminescence from the day of FSH treatment, on the day of superovulatory oestrus and on the day before embryo collection. Compared with the control group, the does that received leptin had a higher number of transferable embryos (p < 0.005), fewer embryos classified as degenerated (p < 0.001) and fewer TUNEL‐positive cells/blastocyst (p < 0.001). The number of transferable embryos was positively correlated with E2 concentrations on day of oestrus (r = 0.562; p < 0.01) and P4 concentrations on the day of embryo collection (r = 0.912; p < 0.001). We concluded that in vivo leptin administration during FSH treatment improved embryo quality and affected ovarian steroidogenesis in superovulated goats. 相似文献
26.
D. Alves Martins E. Gomes P. Rema J. Dias R.O.A. Ozório L.M.P. Valente 《Aquaculture International》2006,14(3):285-295
A shortage of marine raw ingredients, such as fish oil, is predicted in the near future. The use of suitable alternative lipid sources, such as vegetable oils, is crucial for sustainable growth of the aquaculture sector. Three isonitrogenous (50% Crude Protein) and isoenergetic (19 kJ g−1) diets, in which fish oil was gradually replaced by soybean oil (0, 25 and 50% of the oil fraction) were tested for 12 weeks, using European sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss) juveniles. No dietary effects (p>0.05) on growth performance, feed conversion, digestibility or body composition were observed with either species. The results obtained suggest the inclusion of soybean oil up to 50% of the dietary lipid is possible, in diets for sea bass and/or rainbow trout juveniles. 相似文献
27.
Leonardo Manir Feitosa Lucas Pereira Martins Leandro Augusto de Souza Junior Rosangela Paula Lessa 《水产资源保护:海洋与淡水生态系统》2020,30(5):882-891
- Updated distribution ranges are crucial for conservation status assessments. Comprehensive analyses combining published literature and available data on historical catches and species distribution models (SDMs) are effective tools that could improve the prediction of more realistic scenarios for some species, especially those with limited information available and facing multiple threats.
- The present study aimed at generating an updated distribution for the smalltail shark Carcharhinus porosus, one of the most threatened and understudied shark species of the western Atlantic Ocean. Estimates of the key areas for this species conservation based on the SDMs, and trends in catch probabilities throughout its distribution range are provided.
- Four algorithms (BIOCLIM, Domain, Mahalanobis, and Maximum Entropy) were used to model the distribution of C. porosus and calculate its habitat suitability based on marine environmental variables. To assess historical catch probability trends, we built a generalized linear model from published and grey literature data. This analysis was used to estimate catch probability as an indication of population trends.
- SDMs suggest that the northern coast of South America (NCSA) harbours the most suitable habitats for C. porosus in the world, which was expected given its historically high catch rate in this region. In addition, there was a continuously declining catch probability trend starting in the 1970s. However, the decline was smaller for the NCSA as compared with the Gulf of Mexico and the eastern South America coast.
- Results indicate that the NCSA should be considered the currently most important area in the world for this species conservation. Furthermore, the lack of data throughout Central and South American marine regions hampers the evaluation of extinction risk throughout its updated distribution. Thus, research in these areas is urgently required for a more comprehensive conservation status assessment.
28.
Jorge Dias Rebeca Rueda-Jasso Stephan Panserat Luis E C da Conceição Emidio F Gomes & Maria T Dinis 《Aquaculture Research》2004,35(12):1122-1130
A study was undertaken to determine the effect of various dietary carbohydrate‐to‐lipid ratios on growth performance, whole‐body composition and tissue lipid content in Senegalese sole (Solea senegalensis) juveniles. Data on the dietary regulation of key hepatic enzymes of the lipogenic and glycolytic pathways (glucose‐6‐phosphate dehydrogenase, G6PD; malic enzyme, ME; fatty acid synthetase, FAS; pyruvate kinase, PK and glucokinase, GK) were also generated. Four isonitrogenous (crude protein: 52% dry matter (DM)) diets were formulated to contain one of two lipid levels (11% and 21% DM). Within each dietary lipid level, the nature of the carbohydrate fraction (raw or extruded peas) was varied. Triplicate groups of 54 sole (initial body weight: 23.6±1.2 g) were grown in recirculated seawater over 67 days. Fish were fed using automated feeders. At the end of the study, whole‐body, liver, viscera and muscle samples were withdrawn for analyses. During the experimental period, the mean fish weight about doubled in all treatments. No significant differences were found in growth performance (ranging from 1.1% to 1.4% body weight day?1) among dietary treatments. High‐fat diets increased whole‐body fat content. Similarly, daily fat gain ranged from 0.54 to 0.78 g kg?1 day?1 and highest values were found in fish fed high‐lipid diets. Dietary treatments also affected tissue lipid content (liver, viscera and muscle), with highest values in fish fed high‐fat diets. The nature of dietary carbohydrates had little influence on performance criteria, but affected tissue lipid deposition. The activities of G6PD, ME and FAS were depressed by elevated levels of dietary lipid, confirming the inhibitory effect of dietary fats on lipid biosynthesis. At both dietary lipid levels, ME and FAS activities were little affected by dietary carbohydrate. Activities of PK and GK were not affected by the starch level of the diets. In Senegalese sole juveniles, the lipogenic pathway is more susceptible to modulation by dietary means (particularly through lipid intake) than the glycolytic pathway. 相似文献
29.
Pigmentation of gilthead seabream, Sparus aurata (L. 1875), using Chlorella vulgaris (Chlorophyta, Volvocales) microalga 总被引:1,自引:0,他引:1
L Gouveia G Choubert N Pereira J Santinha J Empis & E Gomes 《Aquaculture Research》2002,33(12):987-993
A feeding experiment was conducted over 9 weeks with seven groups of 30 (fish per group) unpigmented gilthead seabream, Sparus aurata (L. 1875) (initial mean weight = 145.2 ± 12.3 g). Three experimental diets were prepared by adding to a basal diet free of carotenoid (final pigment content of around 40 mg per kg feed): (i) a biomass of the carotenogenic Chlorella vulgaris (Chlorophyta, Volvocales); (ii) a synthetic astaxanthin; and (iii) a mixture (1:1) of microalgal biomass and synthetic astaxanthin. At 3‐week intervals, five fish were sampled from each tank for total carotenoids analysis in skin and muscle. The carotenoid pigments (total amount = 0.4%) identified in the carotenogenic alga were lutein (0.3%), β‐carotene (1.2%), canthaxanthin (36.2%), astaxanthin, free and esterified forms (55.0%), and other pigments (7.3%). Carotenoid pigments were significantly deposited in the four skin zones studied during the feeding trial: the forefront between the eyes, the opercule, along the dorsal fin and in the abdominal area. In the muscle, regardless of the astaxanthin source, the amount of carotenoids measured was very low (less than 1 mg kg?1) and differences not significant. Moreover, no muscle pigmentation was evident, and there was no variation in the amount of carotenoid analysed in skin tissue, through the trial, for each treatment. It was concluded that supplementing the feed with C. vulgaris would be an acceptable practice in aquaculture to improve the market appeal of the gilthead seabream. 相似文献
30.
Maria del Carmen González-Peña Santo Z. Gomes Gloria S. Moreira 《Journal of the World Aquaculture Society》2002,33(4):441-447
Feeding experiments were conducted on large and small adult freshwater prawns Macrobrachium rosenbergii (36.96 ± 1.65 and 13.48 ± 1.65 g in weight) to determine the impact of dietary fiber on growth, digestion, and gastric emptying time. Fiber was incorporated as Q- cellulose into four semi-purified diets at calculated levels of 0, 5, 10 and 15% at the expense of starch and fed for an 8-wk period. The experiment was conducted in a closed, filtered, recirculating freshwater system. The results indicate that the specific growth rates, feed conversion ratios, and protein efficiency ratios improved as the levels of dietary fiber increased from 0.4% to 8%. Gastric emptying times increased as the level of inclusion of cellulose in the diets increased. It was concluded that diets containing up to 10% dietary fiber increases growth rates in adult prawn Macrobrachium rosenbergii by increasing nutrient residence time in the gastrointestinal tract, thereby increasing absorption. 相似文献