全文获取类型
收费全文 | 1292篇 |
免费 | 71篇 |
国内免费 | 3篇 |
专业分类
林业 | 143篇 |
农学 | 94篇 |
基础科学 | 16篇 |
327篇 | |
综合类 | 92篇 |
农作物 | 114篇 |
水产渔业 | 95篇 |
畜牧兽医 | 328篇 |
园艺 | 21篇 |
植物保护 | 136篇 |
出版年
2023年 | 12篇 |
2022年 | 35篇 |
2021年 | 37篇 |
2020年 | 47篇 |
2019年 | 41篇 |
2018年 | 56篇 |
2017年 | 65篇 |
2016年 | 51篇 |
2015年 | 34篇 |
2014年 | 53篇 |
2013年 | 116篇 |
2012年 | 74篇 |
2011年 | 85篇 |
2010年 | 63篇 |
2009年 | 52篇 |
2008年 | 65篇 |
2007年 | 27篇 |
2006年 | 45篇 |
2005年 | 25篇 |
2004年 | 25篇 |
2003年 | 35篇 |
2002年 | 32篇 |
2001年 | 35篇 |
2000年 | 23篇 |
1999年 | 22篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 14篇 |
1995年 | 4篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1973年 | 9篇 |
1972年 | 4篇 |
1971年 | 6篇 |
1970年 | 6篇 |
1969年 | 7篇 |
1968年 | 7篇 |
排序方式: 共有1366条查询结果,搜索用时 157 毫秒
151.
Ali Murtaza Waqas Ahmad Tariq Sohail Muhammad Irfan‐ur‐Rehman Khan Imran Mohsin Muhammad Shahzad Mujahid Hussain Muhammad Zahid Tahir Muhammad Ijaz 《Reproduction in domestic animals》2019,54(3):545-550
This study compares the factors associated with variable interval to oestrus and ovulation between early versus late ovulating goats following PGF2α administration. The time of ovulation in Beetal goats (n = 38) was monitored through transrectal ultrasound at every 6 hr following a single dose of PGF2α (experiment 1). Variations in oestrus and ovulation times were further explored through the changes in follicular dynamics, endocrine profiles and behaviour in another set of goats (n = 13) following single PGF2α given randomly during the luteal phase (experiment 2). The ovulation time varied between 60 and 96 hr, and 57% of ovulations occurred by 72 hr following PGF2α (experiment 1). Accordingly, the goats (n = 13) in the second experiment were retrospectively divided either into early and/or late ovulating, that is, ≤72 and/or ≥84 hr following PGF2α. The onset of oestrus, peak estradiol‐17β concentration and LH surge after PGF2α was first observed in early than late ovulating goats (p < 0.05). The goats ovulating early had larger follicle and smaller CL in diameter at the time of PGF2α administration than those ovulating late (5.4 ± 0.2 vs. 4.3 ± 0.2 mm and 10 ± 0.6 vs. 11.8 ± 0.3 mm, respectively; p < 0.05). Likewise, plasma progesterone concentration tended to be lower (p = 0.087) in early than late ovulating goats. In conclusion, the size of dominant follicle and CL at the time of PGF2a determines the interval to ovulation following a single dose of PGF2a during the luteal phase. 相似文献
152.
Shawn‐Elizabeth Maloney Firdous A. Khan Tracy S. Chenier Mariana Diel de Amorim Michael Anthony Hayes Elizabeth L. Scholtz 《Reproduction in domestic animals》2019,54(3):473-479
Proteomic analysis of mare uterine flush fluid provides a minimally invasive technique for studying protein changes associated with the oestrous cycle. The aim of this study was to identify differentially abundant proteins in the uterine flush fluid of mares in oestrus and dioestrus. In this study, uterine flush fluid samples were collected from eight reproductively healthy mares in either oestrus (n = 5) or dioestrus (n = 3). Proteomic analysis was performed using liquid chromatography‐tandem mass spectrometry. Of 172 proteins identified, six proteins (immunoglobulin lambda‐like polypeptide 1, haemoglobin subunit alpha, alpha‐1B‐glycoprotein, serotransferrin, apolipoprotein A‐1, and haemoglobin subunit beta) were significantly more abundant in oestrus. These proteins may contribute to the endometrial defence system through roles in inflammation, immunity or antimicrobial activity. In other species, some of these proteins have been described as immunoglobulins, negative acute phase proteins or defence agents against micro‐organisms. During dioestrus, immunoglobulin alpha‐1 chain C region‐related, complement factor I, CD 109 antigen and uterocalin, were significantly more abundant. Research in other species suggests that these four proteins contribute to the immune response through proposed immunoregulatory characteristics, complement system involvement or roles in B cell–T cell interactions. In conclusion, ten differentially abundant proteins were identified in the uterine flush fluid of mares in oestrus and dioestrus. Targeted studies on these proteins could elucidate their role in uterine defence mechanisms during the oestrous cycle in the mare. 相似文献
153.
Yatoo Mohd. Iqbal Parray Oveas Raffiq Mir Muheet Bhat Riyaz Ahmed Malik Hamid Ullah Fazili Mujeeb ur Rehman Qureshi Sabia Mir Masood Salim Yousuf Raja Wasim Tufani Noor Alam Dhama Kuldeep Bashir Shah Tauseef 《Tropical animal health and production》2019,51(8):2127-2137
Tropical Animal Health and Production - Therapeutic management of contagious caprine pleuroneumonia (CCPP) involves mostly the use of oxytetracycline followed by enrofloxacin and rarely tylosin. In... 相似文献
154.
155.
156.
Livestock production is an integral part of the rain-fed and irrigated agriculture system in Pakistan. Animal production is
closely interlinked with the cropping systems and play a crucial role in the rural economy. Participatory rural appraisals
and economic opportunity surveys were conducted in two ecological zones (irrigated and rain-fed) and two dairy production
systems (peri-urban and mixed livestock). Major constraints in animal health, nutrition and reproduction were identified and
interventions were suggested to overcome these difficulties. The economic opportunity survey revealed that maximum opportunity
to enhance farmers’ income is to increase milk production per day per animal, which can be accomplished through coordinated
improvements in nutrition, reproduction and genetics. 相似文献
157.
Effect of Gibberellic Acid Spray during Ontogeny of Mustard on Growth, Nutrient Uptake and Yield Characteristics 总被引:2,自引:0,他引:2
In a field trial conducted during 1993–1994, mustard ( Brassica juncea L. Czern & Coss.) cv. Varuna was sprayed with either deionised water or 10−5 M GA3 at 40 (vegetative stage), 60 (flowering stage) or 80 (pod fill stage) days after sowing (DAS) to select the suitable growth stage for spray for augmenting productivity of the crop. Shoot length per plant, leaf number per plant, leaf area per plant, dry weight per plant and leaf area index and accumulation of N, P and K were recorded at 100 DAS. Pods per plant, seeds per pod, 1000 seed weight, seed yield, biological yield, harvest index and seed yield merit were computed at harvest. Growth, NPK accumulation and yield were maximal when spraying was done at 40 DAS. However, spraying at 40 and 60 DAS gave at par values for most of the growth and yield parameters. It was also noted that there was a significant difference in spray treatment at different growth stages only when G A, was sprayed and not when water was sprayed. 相似文献
158.
Gluten proteins from two cultivars of hard red spring (HRS) wheat with good and poor breadmaking quality were fractionated into 13 fractions by sequential extraction with dilute hydrochloric acid. Each subfraction was characterized by multistacking (MS) SDS‐PAGE under nonreducing conditions, followed by imaging densitometry. The glutenin polymers from the origins of MS‐SDS‐PAGE were analyzed by SDSP‐PAGE under reducing conditions to determine the composition of high and low molecular weight subunits. The results showed that fractions differed significantly in glutenin‐to‐gliadin ratios and in the size distribution of glutenin polymers. The earlier precipitated fractions were composed of more gliadins but fewer glutenin polymers. However, the glutenin polymers gradually increased in their relative quantities with the residue having the largest glutenin‐to‐gliadin ratio. The size distribution of glutenin polymers differed significantly from early precipitated to later fractions. The relative quantities of glutenin aggregates at the 4% origins increased significantly. The ratio of high molecular weight (HMW) to low molecular weight (LMW) glutenin subunits increased significantly from early to intermediate fractions. Between the two cultivars, significant differences were found in the ratio of HMW to LMW glutenin subunits and quantity of SDS insoluble glutenin polymers in the residue fraction with the better breadmaking quality cultivar ND706 having a greater ratio than the cultivar Sharp. It was concluded that the size distribution of glutenin polymers played an important role in determining the differences in breadmaking quality between the good and poor HRS wheat cultivars. 相似文献
159.
Singh D. Sanyal P.K. Swarnkar C.P. Khan F.A. Bhagwan P.S.K. 《Veterinary research communications》1999,23(4):229-240
The influence of the quality and quantity of diets on the disposition kinetics of albendazole were studied in sheep in two different experiments. The plasma concentration profiles of albendazole sulphoxide and albendazole sulphone were measured following intraruminal administration of albendazole at 5.0 mg/kg body weight in weaner sheep offered three different diets: 100% green Sorghum spp., 100% dry mature Cenchrus ciliaris hay and a 50:50 mix of these two diets. The peak plasma concentrations and the availability of the albendazole metabolites, as measured by the area under the concentration–time curve, were significantly higher (p<0.01) in the animals offered exclusively dry fodder compared to other diets. Changing the diet from dry to green fodder resulted in a significantly lower systemic availability of the drug metabolites. It is suggested that a decreased transit time of the digesta in the bowel on the green diet, with its high water content, limited the systemic availability of the drug by reducing the time available for gastrointestinal absorption.An experiment on the influence of different levels of pretreatment fasting on the pharmacokinetics of albendazole revealed significantly higher (p<0.05) plasma concentrations of the anthelmintically active sulphoxide metabolite from 12 h onwards following administration of the drug in animals subjected to 24 h of pretreatment fasting compared to other groups with pretreatment fasting of 8, 12 or 18 h. The area under the concentration–time curve and the minimum residence time of the drug metabolites were significantly greater (p<0.05) in animals that had been fasted for 24 h. It is suggested that fasting induces a decrease in the flow of digesta through the gastrointestinal tract of ruminants and prolongs the duration of dissolution of the drug, resulting in enhancement of the absorption of albendazole and of the systemic availability of its metabolites. 相似文献
160.
Many predatory arthropods occur naturally in turfgrass, and they provide adequate control of lepidopteran pests, such as fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), and black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae). Recording predation is challenging under field conditions because predators rarely leave any evidence. Clay models were successfully employed for studying predation, and this technique is underutilized in turfgrass. Little is known about whether the characteristics of clay models, such as color, shape, and size, influence arthropod interactions in turfgrass. To improve the utility of clay models in turfgrass, the influence of the color, shape, and size of clay models on arthropod interactions was studied by exposing clay models during daytime and nighttime in a turfgrass field. The results showed that arthropods interacted with clay models, and various types of impressions were recorded, including paired marks, scratches, cuts, and pricks. Although the color of the clay model had no significant effects on arthropod interactions during the night, significantly greater numbers of impressions were noticed on the blue and green models than on the yellow models during the daytime. The caterpillar-shaped models captured significantly greater densities of impressions than the beetle-shaped models. Additionally, the number of impressions significantly increased with an increase in the size of the model regardless of shape. 相似文献