首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   590篇
  免费   45篇
林业   77篇
农学   9篇
基础科学   3篇
  110篇
综合类   5篇
农作物   30篇
水产渔业   75篇
畜牧兽医   201篇
园艺   43篇
植物保护   82篇
  2024年   1篇
  2023年   15篇
  2022年   13篇
  2021年   19篇
  2020年   13篇
  2019年   22篇
  2018年   37篇
  2017年   33篇
  2016年   33篇
  2015年   19篇
  2014年   24篇
  2013年   76篇
  2012年   41篇
  2011年   50篇
  2010年   35篇
  2009年   22篇
  2008年   28篇
  2007年   18篇
  2006年   19篇
  2005年   24篇
  2004年   13篇
  2003年   15篇
  2002年   21篇
  2001年   10篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1997年   2篇
  1996年   4篇
  1995年   2篇
  1993年   2篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1985年   2篇
  1984年   4篇
  1983年   2篇
  1982年   1篇
  1979年   1篇
  1977年   1篇
  1968年   1篇
  1958年   1篇
排序方式: 共有635条查询结果,搜索用时 15 毫秒
611.
In this study, the efficacy of aglepristone and/or intrauterine antibiotic administration for the treatment of bitches with cystic endometrial hyperplasia/pyometra complex was investigated. Twenty-four bitches (5-12 years old) with the diagnosis of pyometra were treated at the University of Kafkas and at Istanbul University. The diagnosis of pyometra was established on the basis of the results of clinical, ultrasonographic and vaginal examinations, the haematological and biochemical findings and the history data. In Group I (n = 13), aglepristone (Antiprogestin, Alizine, Virbac, France; 0.33 ml/kg, s.c.) was administered on days 1, 2, 7, and 14 (day 1: diagnosis). In Group II (n = 11), intrauterine antibiotic treatment was performed according to the antibiogram on days 1, 2, 4, 6, 8 in addition to aglepristone given as in Group I. Clinical and ultrasonographic examinations, haematological results and occurrence of oestrous cycles revealed that the ratio of effectively treated bitches was 6/13 and 9/11 in Groups I and II, respectively.  相似文献   
612.
Seroprevalence of five different Leptospira interrogans serovars, Toxoplasma gondii and Leishmania infantum in stray dogs in Ankara was investigated. A total of 116 dog sera collected from apparently healthy stray dogs were tested for L. interrogans serovars by microscopic agglutination test (MAT), for T. gondii antibodies by Sabin-Feldman dye test (SFDT), and for L. infantum antibodies by indirect fluorescence antibody test (IFAT). Of the 116 dogs, 51 (43.96%) were seropositive for leptospirosis, 72 (62.06%) for T. gondii and 3 (2.58%) for L. infantum. No statistically significant difference was observed between male and female dogs in the seroprevalences of toxoplasmosis and leptospirosis (P>0.05), but statistically significant difference was observed among different age groups in the seroprevalences of toxoplasmosis and leptospirosis (P<0.05). Although the seroprevalence of L. infantum was low, asymptomatic animals should be considered as a reservoir for the spread of the disease.  相似文献   
613.
In this study, fractional excretions (Fe) of sodium (Na), potassium (K), chloride (Cl), calcium (Ca), magnesium (Mg) and phosphorus (PO4) were examined with the aim to demonstrate interactions between fractional excretions of these electrolytes within each period and relate them to electrolyte metabolism in clinically normal cows at different stages of lactation and dry period. The material of this study consisted of 20 clinically healthy Holstein-Friesian cows of the same age and milk yield. Blood and urine samples were collected on 190-200th, 240-250th and 270-280th days of pregnancy and on days 1-7th, 35-45th and 75-85th after calving, altogether 6 times. An increase was observed in FeCa and FeMg during the transition from the lactation to the dry period (p < 0.05), and a decrease in FeCa (p < 0.05), FeMg (p < 0.01) in the 2nd month of the dry period. FePO4 and FeMg, respectively, increased on levels of p < 0.01 and p < 0.05, while FeCa decreased on a level of p < 0.05 after gestation compared to the level before gestation. FeNa and FeK showed a decrease of p < 0.001 and p < 0.01, respectively, between the 1st and 2nd months of the dry period, while after gestation this value showed an increase in FeNa (p < 0.05) and FeK (p < 0.01). FeCl increased significantly (p < 0.05) only from postpartum to the 1st month of lactation. There was a strong positive correlation between FeNa and FeCl in all of the periods. It was concluded that there were significant changes in the Fe of Na, K, Cl, Ca, PO4 and Mg before parturition and during lactation; these changes could have an important role in assessing renal function and electrolyte balance.  相似文献   
614.
In this study, the effects of tilmicosin on some haematological and biochemical variables were investigated. Ten male New Zealand rabbits were used as material. The tilmicosin was injected (25 mg/kg body weight, subcutaneously as a single injection), and the rabbits were monitored for 4 days. No negative effects of tilmicosin on haematological and biochemical variables were observed, but it did cause a temporary decrease in red and white blood cell counts.  相似文献   
615.
Three forest pest species of the genusRhyacionia Hübner [1825] (Lepidoptera: Tortricidae) that are known to damagePinus species are found in Turkey:R. buoliana ([Denis & Schiffermüller], 1775),R. pinicolana, (Doubleday, 1849) andR. pinivorana (Lienig & Zeller, 1846).R. pinivorana is recorded for the first time from Turkey.R. pinicolana, first recorded in 1999, is now reported for the second time from Turkey. Photographs are presented of adult males and their genitalia of all taxa and the species distribution is shown on a map.  相似文献   
616.
In the present study, effects of enrofloxacin on biochemical, haematological and blood gas parameters were investigated. Changes in laboratory parameters were monitored during the treatment period. Enrofloxacin was administered (5 mg/kg intramuscularly, once daily) to 10 healthy dogs for 14 days. Acidosis and temporary increases in aspartate aminotransferase, indirect bilirubin, sodium, partial pressure of CO2 and mean corpuscular volume levels as well as decreased levels of inorganic phosphorus, ionized calcium, potassium, partial pressure of O2 and standard bicarbonate were observed. The results of this study suggest that these observed effects of enrofloxacin on blood gas parameters should be taken into consideration in long-term use of the drug.  相似文献   
617.
618.
Porcine circovirus type 2 (PCV2) has been demonstrated to be the causal agent for postweaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS). This report describes the first detection of PCV2 and associated diseases in a Romanian swine herd located in Transylvania. The clinical signs, pathological and histopathological changes observed in affected pigs were similar to those previously described for PDNS and PMWS. Polymerase chain reaction and in situ hybridisation were used for the detection of PCV2 nucleic acids from tissues and serum samples. Complete PCV2 genomes of both PMWS and PDNS cases were sequenced and analysed, and by comparing them with each other no genomic differences could be detected. The sequence analysis showed that the Romanian PCV2 was closely related to PCV2 identified in France and in Hungary.  相似文献   
619.

We present a model for conducting dynamic treatment unit (DTU) forest planning using a heuristic cellular automata (CA) approach. The clustering of DTUs is driven by entry costs associated with treatments, thus we directly model the economic incentive to cluster. The model is based on the work presented in the literature but enhanced by adding a third phase to the CA algorithm where DTUs are mapped in high detail. The model allows separate but nearby forest areas to be included in the same DTU and shares the entry cost if they are within a defined distance. The model is applied to a typical long-term forest planning problem for a 1 182 ha landscape in northern Sweden, represented by 4 218 microsegments with an average size of 0.28 ha. The added phase increased the utility by 1.5–32.2%. The model produced consistent solutions—more than half of all microsegments were managed with the same treatment program in 95% of all solutions when multiple solutions were found.

  相似文献   
620.
The aim of this research was to determine the effects of coating broiler hatching eggs with chitosan on egg quality, embryonic growth, hatching results and chick quality. Eggs obtained from old broiler breeder, aged 59 weeks, were used. Eggs were divided into two groups (coated with chitosan and uncoated) groups. Each group was divided into three groups according to the storage period. Eggs were stored for periods of 1, 4 and 7 days at 15°C and 80% humidity. Then, they were incubated. Storage period of eggs up to 7 days did not affect the egg quality, egg weight loss, embryo growth, chick properties and hatchability of fertile eggs. However, embryo development, relative residual yolk sac weight and relative chick weight were affected by coating eggs with chitosan. Interaction was not found between storage lengths and coating of eggs with chitosan for all examined parameters. The results of the present study suggested that hatching eggs obtained from old broiler breeder flocks were immersed into chitosan solution once and quickly have negative effect on the embryo weight, yolk sac absorption and relative chick weight. It has been observed that covering the hatching eggs with chitosan is not suitable in this respect even if immersion takes place once and in a short time.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号