全文获取类型
收费全文 | 819篇 |
免费 | 48篇 |
专业分类
林业 | 51篇 |
农学 | 128篇 |
基础科学 | 22篇 |
149篇 | |
综合类 | 54篇 |
农作物 | 61篇 |
水产渔业 | 36篇 |
畜牧兽医 | 289篇 |
园艺 | 11篇 |
植物保护 | 66篇 |
出版年
2021年 | 12篇 |
2020年 | 23篇 |
2019年 | 14篇 |
2018年 | 19篇 |
2017年 | 31篇 |
2016年 | 26篇 |
2015年 | 21篇 |
2014年 | 22篇 |
2013年 | 56篇 |
2012年 | 44篇 |
2011年 | 39篇 |
2010年 | 31篇 |
2009年 | 30篇 |
2008年 | 31篇 |
2007年 | 27篇 |
2006年 | 20篇 |
2005年 | 25篇 |
2004年 | 13篇 |
2003年 | 17篇 |
2002年 | 23篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1996年 | 7篇 |
1994年 | 11篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 18篇 |
1987年 | 18篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 6篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1975年 | 13篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 7篇 |
1970年 | 11篇 |
1969年 | 13篇 |
1968年 | 6篇 |
1967年 | 5篇 |
排序方式: 共有867条查询结果,搜索用时 15 毫秒
91.
Das A Katole S Kumar A Gupta SP Saini M Swarup D 《Journal of animal physiology and animal nutrition》2012,96(3):442-449
A feeding trial was conducted to determine the optimum level of crude protein (CP) in the diet of captive blackbuck (Antelope cervicapra) in which feed consumption and nutrient utilization are maximal. Fifteen blackbucks (BW 25-34 kg) were distributed into three groups of five each in an experiment of 75-days duration including a digestion trial of 5-day collection period. All the animals were offered 200 g of concentrates and fresh maize fodder ad libitum. The overall CP content of the three respective diets was 6.9%, 10.4% and 12.7%. Blood samples were collected on the last day of the experiment. Intake and digestibility of CP increased (p < 0.01) with the increased level of CP in the diet. Feed consumption and nutrient intake were not significantly different among the groups. However, digestibilities of most of the nutrients were higher in the 10.4% CP diet than in the 6.9% CP diet. The endogenous loss of nitrogen was similar among the groups. Based on the endogenous losses, minimum N requirement was calculated to be 776 mg/kg BW(0.75) /day, and to meet this requirement, diet must contain at least 8.27% CP. Serum urea nitrogen concentration increased (p < 0.01) with increased level of dietary CP. Serum level of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase was higher (p < 0.05) in the group fed 6.9% CP diet. Animals in the group fed low protein diet also lost body mass during the experimental period. It was concluded that a diet containing 10.4% CP was optimum for maximizing nutrient utilization without any adverse effect on voluntary feed consumption and serum metabolite profile of blackbucks. 相似文献
92.
G Elamaran KP Singh MK Singh SK Singla MS Chauhan RS Manik P Palta 《Reproduction in domestic animals》2012,47(6):1027-1036
This study examined the effects of O2 concentration (5% vs 20%) during in vitro maturation (IVM), fertilization (IVF) and culture (IVC) or supplementation of IVM and IVC media with cysteamine (50 and 100 μm , respectively; IVM, IVF and IVC carried out in 20% O2), on blastocyst rate and relative mRNA abundance of some apoptosis‐related genes measured by real‐time qPCR in immature and in vitro‐matured buffalo oocytes and in embryos at 2‐, 4‐, 8‐ to 16‐cell, morula and blastocyst stages. The blastocyst rate was significantly higher (p < 0.05) while the percentage of TUNEL‐positive cells was significantly lower (p < 0.05) under 5% O2 than that under 20% O2. The mRNA expression of anti‐apoptotic genes BCL‐2 and MCL‐1 was significantly higher (p < 0.05) and that of pro‐apoptotic genes BAX and BID was lower (p < 0.05) under 5% O2 than that under 20% O2 concentration at many embryonic stages. Following cysteamine supplementation, the blastocyst rate and the relative mRNA abundance of BCL‐XL and MCL‐1 was significantly higher (p < 0.05) and that of BAX but not BID was lower (p < 0.05) at many stages of embryonic development, although it did not affect the percentage of TUNEL positive cells in the blastocysts significantly. The mRNA expression pattern of these genes during embryonic development was different in 5% vs 20% O2 groups and in cysteamine supplemented vs controls. At the 8‐ to 16‐cell stage, where developmental block occurs in buffalo, the relative mRNA abundance of BCL‐2 and MCL‐1 was highest under 5% O2 concentration and that of BAX and BID was highest (p < 0.05) under 20% O2 concentration. These results suggest that one of the mechanisms through which beneficial effects of low O2 concentration and cysteamine supplementation are mediated during in vitro embryo production is through an increase in the expression of anti‐apoptotic and a decrease in the expression of pro‐apoptotic genes. 相似文献
93.
Kazmi I Rahman M Afzal M Gupta G Saleem S Afzal O Shaharyar MA Nautiyal U Ahmed S Anwar F 《Fitoterapia》2012,83(1):142-146
A new stearoyl glucoside of ursolic acid, urs-12-en-3β-ol-28-oic acid 3β-d-glucopyranosyl-4′-octadecanoate and other compounds were isolated from the leaves of Lantana camara L. The structure of this new glycoside was elucidated and established by standard spectroscopic methods. In streptozotocin-induced diabetic rats it showed significant reduction in blood glucose level. 相似文献
94.
95.
Objective The aims of this study were (1) to determine the efficacy of adeno‐associated vector serotype 5 (AAV5) for delivering gene therapy to canine corneal fibroblasts (CCFs) and myofibroblasts (CCMs) using enhanced green fluorescent protein (GFP) marker gene and (2) to evaluate the cytotoxicity of AAV5 to CCFs and CCMs using an in vitro model. Methods Healthy donor canine corneas were used to generate primary CCFs by growing cultures in minimal essential medium supplemented with 10% fetal bovine serum. Canine corneal myofibroblasts were produced by growing cultures in serum‐free medium containing transforming growth factor β1 (1 ng/mL). An AAV5 titer (6.5 × 1012 μg/mL) expressing GFP under control of hybrid cytomegalovirus + chicken β‐actin promoters (AAV5‐gfp) was used to transduce CCF and CCM cultures. Delivered gene expression in CCFs and CCMs was quantified using immunocytochemistry, fluorescent microscopy, and real‐time PCR. Transduction efficacy of the AAV5 vector was determined by counting DAPI‐stained nuclei and EGFP‐positive cells in culture. Phase‐contrast microscopy, trypan blue, and dUTP nick end labeling (TUNEL) assays were used to determine the toxicity and safety of AAV5 in this canine corneal model. Results Topical AAV5 application successfully transduced a significant population of CCFs (42.8%; P < 0.01) and CCMs (28%; P < 0.01). Tested AAV5 did not affect CCF or CCM phenotype or cellular viability and did not cause significant cell death. Conclusions The tested AAV5 is an effective and safe vector for canine corneal gene therapy in this in vitro model. In vivo studies are warranted. 相似文献
96.
Establishment of ornamental and aesthetic plants in hot, arid conditions of India is difficult due to the prevailing climatic, edaphic and biotic factors. Effect of turfgrass on the growth of ornamental plants in hot arid conditions has not been studied so far anywhere in the world. A study was conducted on the campus of Arid Forest Research Institute, Jodhpur, India to assess the performance of a few ornamental plant species in combination with turfgrass and without turfgrass with respect to different soil tilling intervals. Growth of plants was better with turfgrass than without turfgrass. We suggest adopting a soil tilling interval of 30 days to achieve optimum growth of ornamental plant species in terms of height and crown diameter. Our results can help reduce labor costs and achieving better landscapes in fewer days in hot urban conditions of Indian sub continent. 相似文献
97.
Sarika Gupta Kajal Kumari Mehanathan Muthamilarasan Alagesan Subramanian Manoj Prasad 《Plant Breeding》2013,132(4):367-374
Although the foxtail millet [Setaria italica (L.) P. Beauv.] is recently regarded as a model crop for studying functional genomics of biofuel grasses, its genetic improvement to some extent was limited due to the non‐availability of molecular markers, particularly the microsatellite markers and the saturated genetic linkage map. Considering this, we attempted to generate a significant number of microsatellite markers in cultivar ‘Prasad’. Two hundred and fifty‐six clones were sequenced to generate 41.82‐kb high‐quality sequences retrieved from genomic library enriched with dinucleotide repeat motifs. Microsatellites were identified in 194 (76%) of the 256 positive clones, and 64 primer pairs (pp) were successfully designed from 95 (49%) unique SSR‐containing clones. The 67.4% primer designing ability, 100% PCR amplification efficiency and 45.3% polymorphic potential in the parents of F2 mapping population established the efficacy of genomic microsatellites. All the 64 microsatellite markers displayed high level of cross‐species amplification (~67%) in 10 millets and non‐millets species. These experimental findings suggest the utility and efficacy of SSRs in diverse genotyping applications, resolving QTLs, phylogenetic relationships and transferability in several important grass species. 相似文献
98.
99.
100.
A. Das S. Katole M. Choubey S. P. Gupta M. Saini V. Kumar D. Swarup 《Journal of animal physiology and animal nutrition》2013,97(1):80-90
A feeding trial was conducted to know the level of concentrates in the diet of Antelope cervicapra at which diet digestibility and mineral utilization were optimum. Fifteen blackbucks (25–33 kg BW) were distributed into three groups of five each. Fresh oat (Avena sativa) and berseem (Trifolium alexandrinum) fodders were offered ad libitum to all the animals. In addition, animals in groups II and III received concentrate mixture at the rate of 0.5 and 1% of BW, whereas animals in group I received no concentrates. As the level of concentrates increased, consumption of fodder decreased resulting in decreased consumption of neutral detergent fibre (NDFom), acid detergent fibre (ADFom), hemicellulose and cellulose. However, overall total dry matter (DM) and organic matter (OM) intake was not significantly different between the groups. Digestibility of DM, OM and gross energy (GE) increased while that of NDFom and ADFom decreased with increased level of concentrates in the diet. Intake of P, Zn, Cu and Mn increased with increased level of concentrate supplementation; however, consumption of Ca and Fe followed the reverse trend. Absorption of P and Zn increased with increased level of concentrate supplementation. Serum concentration of Zn increased when concentrate was supplemented at the rate of 0.5% BW beyond which there was no further improvement. Increasing the level of concentrates in the diet was resulted in increased serum glucose and cholesterol levels. Forage‐only diet was inadequate in supply of energy, P and zinc. Supplementation of concentrates at the rate of 0.5% BW was able to meet the requirement of these nutrients. Supplementation at the rate of 1% BW supplied energy and P in excess of requirement. It was concluded that the feeding of concentrates to the captive blackbuck fed forage‐based diets should be restricted to 0.5% of BW. 相似文献