全文获取类型
收费全文 | 884篇 |
免费 | 67篇 |
专业分类
林业 | 47篇 |
农学 | 52篇 |
基础科学 | 3篇 |
154篇 | |
综合类 | 114篇 |
农作物 | 46篇 |
水产渔业 | 84篇 |
畜牧兽医 | 352篇 |
园艺 | 22篇 |
植物保护 | 77篇 |
出版年
2022年 | 12篇 |
2021年 | 18篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 19篇 |
2016年 | 19篇 |
2015年 | 26篇 |
2014年 | 15篇 |
2013年 | 33篇 |
2012年 | 46篇 |
2011年 | 52篇 |
2010年 | 23篇 |
2009年 | 32篇 |
2008年 | 42篇 |
2007年 | 43篇 |
2006年 | 40篇 |
2005年 | 38篇 |
2004年 | 33篇 |
2003年 | 44篇 |
2002年 | 36篇 |
2001年 | 18篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 14篇 |
1978年 | 10篇 |
1976年 | 12篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1972年 | 9篇 |
1971年 | 6篇 |
1970年 | 6篇 |
1969年 | 7篇 |
1966年 | 7篇 |
排序方式: 共有951条查询结果,搜索用时 31 毫秒
941.
Roy Shaw C. D. Evans Shirley Munson G. R. List K. Warner 《American Journal of Potato Research》1973,50(12):424-430
Two pilot plant runs of 23 hours each were made with peeled and unpeeled potatoes. Samples of chips were taken at intervals and subjected to sensory evaluation after acceclerated storage at 60 C and room temperature storage for 1, 3, 6, and 9 weeks. Samples of oil were taken at intervals and analyzed for color free fatty acids, peroxide values, and copper. Chips from peeled and unpeeled potatoes were similar in all evaluations. There was a significant increase in yield of chips from unpeeled potatoes. 相似文献
942.
Roy L. Flannery 《American Journal of Potato Research》1972,49(12):489-489
943.
Nutritive value of rapeseed proteins and fractions supplemented with methionine and tyrosine in rats
J. Delisle J. Amiot F. Dauphin A. Roy G. J. Brisson J. D. Jones 《Plant foods for human nutrition (Dordrecht, Netherlands)》1987,37(2):109-116
Rapeseed protein concentrate (RPC), rapeseed 2S and 12S fractions, a blend of 2S and 12S fractions, retentate (RET) and precipitate (PRE) proteins obtained during rapeseed fractionation were compared to casein for nutritive value as determined by net protein ratio (NPR) and apparent digestibility coefficient (ADC). Tyrosine concentration in rapeseed 2S fraction was the lowest compared to all other protein sources and methionine was the first limiting amino acid. The NPR and ADC of RPC, RET, and fraction 12S did not change significantly (P<0.05) following supplementation with methionine, but for PRE the NPR was decreased significantly (P<0.05). However, the rapeseed 2S fraction supplemented with tyrosine had a NPR significantly (P<0.05) higher than that of RPC and not significant (P<0.05) different from that of casein. The NPR of the 2S and 12S blend was significantly (P<0.05) higher than that of RET and PRE; however, no significant (P<0.05) difference was observed in NPR and ADC of the blend when supplemented with tyrosine. The nutritive value and digestibility of rapeseed 2S fraction were improved by supplementation with tyrosine and by blending with the 12S fraction. 相似文献
944.
Green leafy vegetables are the most underexploited class of vegetablesdespite high nutritional value. Reports on nutritional composition andstorage of some of the fresh leaves are available but the storage behaviorof dehydrated leaves apparently has not been studied. Therefore, in thepresent study, two green leafy vegetables, savoy beets (Beta vulgarisvar. bengalensis) and fenugreek (Trigonella foenumgraecum) were dehydrated in a low temperature drier and stored for9 months under ambient and cold stored conditions after packaging insingle or double layers of high density polyethylene film (200 gauge). Thequality was determined on the basis of retention of -carotene,ascorbic acid and chlorophyll, and the extent of browning during storage.Retention of these quality characteristics depended on the crop and storageconditions. Double packed and cold stored samples of fenugreek retained67% -carotene, whereas savoy beet leaves retained only 57% ofthe initial -carotene under similar conditions. Similarly, higherretention of ascorbic acid and chlorophyll, and lower browning wasobserved in double packed, cold stored samples. Results indicated theefficacy of double packed and cold stored samples over other combinations. 相似文献
945.
Israr Majeed Kaushal K. Garg A. Venkataradha Naveen K. Purushothaman Sourav Roy Nagarjuna N. Reddy Ramesh Singh K. H. Anantha Sreenath Dixit Bhabani S. Das 《European Journal of Soil Science》2023,74(2):e13358
Rapid soil testing and soil quality assessment are essential to address soil degradation and low farm incomes in smallholder farms. With the objective of testing diffuse reflectance spectroscopy (DRS) to rapidly assess soil chemical properties, nutrient content and a soil quality index (SQI), samples of surface soil were collected from 1113 smallholder farms in seven districts in Bundelkhand region of Uttar Pradesh, India. A minimum dataset (MDS) approach was followed to estimate SQI using the three chemical parameters of soil pH, electrical conductivity (EC) and soil organic carbon (SOC), and 11 different soil nutrients. Principal component and correlation analyses showed that soil pH, SOC content and three available nutrients − copper (Cu), iron (Fe) and sulphur (S) − may constitute the MDS. Estimated SQI values showed strong positive correlation with crop yields. Results of chemometric modelling showed that the DRS approach could yield the coefficient of determination (R2) values in the validation datasets ranging from 0.79 to 0.94 for exchangeable calcium (Ca) followed by 0.67–0.88 for exchangeable potassium (K), 0.52–0.86 for SOC and 0.53–0.81 for available boron (B) content. Except in one district, the DRS approach could be used to estimate SQI values with R2 values in the range of 0.63–0.81; an R2 value of 0.71 was obtained in the pooled dataset. We also estimated the three-tier soil test crop response (STCR) ratings to compare DRS and wet chemistry soil testing approaches. Similar STCR ratings were obtained for both these approaches in more than 86% of the samples. Parameters for which both the methods yielded similar ratings in more than 80% of the samples were EC (>98%), pH and exchangeable Ca (>81%) and available B (>89%). With similar ratings, these results suggest that the DRS approach may safely be used for farmers' fields, replacing the traditional wet analysis approach of soil testing. 相似文献
946.
A study was conducted on twenty indigenous goat kids allocated into two different groups. All animals were offered ad libitum rice straw and berseem hay (40:60). Group I (T1) was fed concentrate mixture (100 g/d). Group II (T2) was supplemented with urea molasses mineral block (200 g/d). The experiment lasted for 90 days. There was significant decrease
in serum sodium (60.68 mEq/L), increase in serum potassium (34.50 mEq/L) and increased activity of AST (340.42 U/L) and ALT
(164.96 U/L) was observed in kids of group T2 in comparison to the controls (T1). On histopathological examination mild degenerative changes in kidney of group T2 with congestion in intertubular vessel, granular cytoplasm of the epithelial cells in PCT and DCT, necrosis and swelling
of the epithelial cells, congestion of vessels and cloudy swelling was observed in PCT and DCT. Albuminious mass was also
present in tubule. On histopathological observation of liver of kid of group T2 oedema in liver parenchyma and proliferation of fibrious tissue in periportal area was observed. 相似文献
947.
Montoliu L Roy R Regales L García-Díaz A 《Comparative immunology, microbiology and infectious diseases》2009,32(2):81-90
The design of transgenes has always been limited by the extent of available information on the endogenous locus whose expression pattern had to be replicated. Those genes whose expression domain had not been entirely documented resulted, usually, in transgenes with an unpredictable expression patterns and suboptimal performance in transgenic animals. The use of genomic comparative approaches, highlighting evolutionary conserved homologous DNA sequences, helps to identify crucial regulatory elements that are associated to a given expression domain. The inclusion of these conserved regulatory sequences in transgenic constructs would normally result in optimal expression levels of transgenes in recipient animals. The use of artificial chromosome-type transgenes usually ensures the inclusion of these preserved regulatory elements that are required for the faithful expression of the gene. These constructs could also contain insulators, a subset of regulatory sequences whose application is being addressed in transgenesis. Therefore, the generation of transgenic animals with genomic-type constructs is the recommended approach to achieve optimal transgene expression, according to the expected pattern of the corresponding endogenous locus. 相似文献
948.
The objectives of this study were to establish the characteristics of oestrous behaviour in Ovsynch (induction of ovulation through administration of GnRH-PGF2-GnRH in a systemic manner on 0, seventh and ninth day respectively) and Ovsynch plus Norprolac (Quinagolide hydrochloride – an inhibitor of prolactin secretion) treated Murrah buffalo heifers and to determine the relationships between this behaviour and the plasma concentrations of oestradiol-17β (E2), total oestrogen, and progesterone. Oestrus was detected by visual observations of oestrus signs, per rectal examination of genitalia and bull parading thrice a day during treatment period. Among all the symptoms, it was observed that bull mounting of heifers in oestrus was highest. Examination of genital tracts per rectum revealed that the cervix was relaxed, uterus was turgid and ovaries had palpable follicle in animals with oestrus. The peak concentrations of E2 (10.81 ± 0.62 pg/ml) and total oestrogen (17.11 ± 1.21 pg/ml) occurred at 9.45 ± 0.85 and 9.64 ± 0.93 h after second GnRH administration, respectively, in Ovsynch treated animals. However, the peak levels of E2 (20.02 ± 2.87 pg/ml) and total oestrogen (32.71 ± 3.15 pg/ml) occurred at 10.18 ± 0.50 and 10.36 ± 0.75 h after second GnRH administration, respectively, in Ovsynch plus Norprolac treated animals. Plasma progesterone concentration was basal (0.20 ± 0.001 ng/ml) during the peri-oestrus period. The plasma progesterone concentration was the lowest on the day of oestrus and increased to register a peak on day 13 ± 2 of the cycle. Oestrous behaviour was positively correlated with the peak concentration of E2 (p < 0.001) and total oestrogen (p < 0.001) during the peri-oestrus period. Inhibition of prolactin by Norprolac administration significantly increased the concentration of E2 and total oestrogen during oestrus in buffaloes in comparison to those recorded in animals subjected to Ovsynch protocol alone. In conclusion, our results suggest that the peak concentrations of E2 and total oestrogen and mean level of E2 and total oestrogen during the peri-oestrus period are the important factors contributing the behavioural manifestation of oestrus in buffalo cows. 相似文献
949.
Olivia A. Petritz Natalie Antinoff Catherine Pfent Wayne Corapi Roy R. Pool Michelle Fabiani Sue Chen 《Journal of Exotic Pet Medicine》2013,22(3):287-292
A 4-year-old, castrated, male domestic ferret (Mustela putorius furo) was evaluated for a possible upper respiratory tract infection and wheezing for approximately 3 weeks. Supportive care for a suspected upper respiratory tract infection was initiated; however, the patient became progressively more dyspneic over the next 48 hours. A possible tracheal mass was identified upon thoracic radiographic imaging of the ferret. Tracheoscopy and a computed tomography scan of the neck and thorax confirmed the presence of a tracheal mass approximately 3 cm from the larynx obstructing 80% of the tracheal lumen. Rather than pursuing surgical resection, the owners elected humane euthanasia. An adenosquamous carcinoma of the trachea was diagnosed after histologic analysis. This tumor type has been diagnosed in the lungs of ferrets that were experimentally exposed to carcinogens found in cigarette smoke; however, there are no previous reports of this or any other tumor type associated with the ferret trachea. A tracheal mass causing a partial upper airway obstruction should be considered within the differential disease diagnosis list when a ferret is presented with dyspnea. 相似文献
950.
Arabinofuranosyl groups are present in many hemicelluloses as single or multiple units attached to the main xylan or galactan chain where they are sensitive to acid hydrolysis. Under acidic conditions of the human stomach, up to 10% of the L‐arabinose is released from the hemicellulose of corn hull, larch wood, and banana peel hemicellulose. 相似文献