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   88篇
  免费   5篇
林业   4篇
农学   14篇
基础科学   2篇
  20篇
综合类   5篇
农作物   7篇
畜牧兽医   33篇
园艺   2篇
植物保护   6篇
  2023年   1篇
  2022年   1篇
  2021年   2篇
  2020年   4篇
  2019年   5篇
  2018年   4篇
  2017年   3篇
  2015年   1篇
  2014年   1篇
  2013年   6篇
  2012年   1篇
  2011年   4篇
  2010年   3篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2006年   2篇
  2005年   5篇
  2004年   2篇
  2003年   2篇
  2002年   5篇
  2000年   2篇
  1998年   1篇
  1997年   3篇
  1996年   1篇
  1995年   3篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1988年   2篇
  1983年   3篇
  1982年   1篇
  1981年   1篇
  1979年   2篇
  1977年   1篇
  1975年   1篇
  1973年   1篇
  1971年   3篇
  1969年   2篇
  1968年   1篇
  1966年   1篇
排序方式: 共有93条查询结果,搜索用时 171 毫秒
81.
Iron-manganese concretions from three reference soil series of the Indo-Gangetic plain of Punjab have been investigated for their composition, micromorphology and mineralogy. The data show that amounts of Fe, Mn, Co, Ni, Cu and Zn in the concretions are higher than in the surrounding soil matrix. The contents of Mn, Co and Ni increase and that of Fe decreases with the increasing size of concretions. Cu or Zn contents do not show any systematic differences with concretion size. A major portion of these elements is oxalate- and dithionite-extractable. A minor fraction is present in the silicate structure as well as in the pyrophosphate-extractable forms. The Fe and Mn compounds present in the concretions are x-ray amorphous. The concretions appear to have developed in situ.  相似文献   
82.
Genotypic variation for morpho-physiological parameters, phosphorus (P) content and root acid phosphatase activity was studied in 52 pigeonpea genotypes. Data related to shoot (length, dry weight, number of leaves, and leaf area), root (volume, length, dry weight, area, perimeter, and number of root tips), acid phosphatase activity, and P content (root, stem, and leaf) were recorded at 60 days after sowing (DAS). The P use efficient genotypes showed high root length, root area, root perimeter, root dry weight, P content in leaves, and root to shoot dry weight ratio under the P not added condition. Significant variation was found among genotypes for root- and shoot-associated characteristics under both P treatments. The P use efficient genotypes with improved root morphological phenes have potential to acquire and utilize more P from immobile soil bound P sources may be of additional factor for increasing efficiency of acquisition and utilization of supplied P fertilizer.  相似文献   
83.
Pharmacokinetic (PK)–pharmacodynamic (PD) integration of crystalline ceftiofur‐free acid (CCFA) was established in six healthy female goats administered subcutaneously (s.c.) on the left side of the neck at a dosage of 6.6 mg/kg body weight. Serum concentrations of ceftiofur and desfuroylceftiofur (DFC) were determined using high‐performance liquid chromatography. Mutant prevention concentration (MPC), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ceftiofur were determined for Pasteurella (P.) multocida. Mean terminal half‐life and mean residence time of ceftiofur + DFC were 48.6 h and 104 h, respectively. In vitro plasma protein binding of ceftiofur was 46.6% in goats. The MIC and MBC values of ceftiofur were similar in serum and MHB and a very small difference between these values confirmed bactericidal activity of drug against P. multocida. In vitro and ex vivo time–kill curves for P. multocida demonstrated a time‐dependent killing action of drug. Considering target serum concentration of 0.20 μg/mL, PK‐PD values for AUC24 h/MIC90 and T > MIC90, respectively, were 302 h and 192 h against P. multocida. A MPC/MIC ratio of 10–14 indicated that selective pressure for proliferation of resistant mutants of P. multocida is minimal after CCFA single‐dose administration. Based on MPC = 1.40 μg/mL for P. multocida, the PK‐PD indices, viz. T > MPC and AUC24/MPC, were 48 h and 43 h, respectively. The data suggested the use of single dose (6.6 mg/kg, s.c.) of CCFA in goats to obtain clinical and bacteriological cure of pneumonia due to P. multocida.  相似文献   
84.
A tissue chamber model of acute inflammation for use in comparative studies in calves, sheep, goats and pigs has been established and validated. Tissue chambers were prepared from silicon rubber tubing, of inner diameter 12.7 mm, length 115 mm and volume 15 ml, with 10 holes, each of 6mm diameter, at each end. In each animal two or four chambers were inserted at subcutaneous sites. Six weeks after implantation an acute inflammatory reaction in a single cage was generated by the intracaveal injection of 0.5 ml of 1% carrageenan solution. Serial samples of exudate (injected chamber), transudate (non-injected chamber) and blood were collected for measurement of exudate and transudate leucocyte count, prostaglandin (PG)E(2) concentration in exudate and serum thromboxane (Tx)B(2) concentration. In addition, skin temperature changes over exudate and transudate chambers were recorded. In all four species, carrageenan induced an acute inflammatory response, indicated by increases to peak values followed by return towards baseline in skin temperature, leucocyte count and PGE(2) concentration. For each of these variables in calves, sheep and goats the increases were significantly greater for exudate than for transudate. The degree of intra-species variation in each variable was acceptable. Marked inter-species differences were recorded: skin temperature rise was greatest in calves and least in sheep and goats; exudate PGE(2) concentration was increased in the order sheep>goat>pig>calf; serum TxB(2) concentration was increased in the order calf>goat>sheep>pig and exudate leucocyte count was increased to a greater extent in the pig than in the three ruminant species. The model has advantages over some previously described tissue chamber models of inflammation and will be suitable for use in comparative studies of inflammatory mechanisms and the pharmacokinetics and pharmacodynamics of anti-inflammatory drugs.  相似文献   
85.
The presence of immunoreactive prolactin, luteinizing hormone (LH) and progesterone in buffalo seminal plasma is reported for the first time. Correlations were obtained between various semen attributes and the levels of the above immunoreactive hormones. Statistically significant (P < 0.01) negative correlations were found between the levels of immunoreactive prolactin in semen and sperm motility and viability. The coefficient of multiple linear correlation (R2) between the levels of immunoreactive progesterone, prolactin and LH in the seminal plasma and the various attributes of semen revealed that immunoreactive progesterone and prolactin showed stronger interactions than did LH. The biological significance of these immunoreactive hormones in semen is discussed.  相似文献   
86.
The efficacy of two formulations of abamectin, i.e. oral and injectable was determined against ivermectin-resistant strain of T. colubriformis in sheep. Twenty-four lambs were infected with 10,000 third stage larvae of ivermectin-resistant strain of T. colubriformis. Twenty-four days post-infection, the lambs were divided randomly into four groups of six animals each according to egg counts. The first group was left untreated and kept as a control. The second group was treated with ivermectin (oral) at 0.2mg kg(-1) body weight. The third group was treated with oral formulation of abamectin at 0.2mg kg(-1) body weight. The fourth group was treated with injectable formulation of abamectin at 0.2mg kg(-1) body weight. Fecal egg count and controlled slaughter tests were employed to determine the efficacy of abamectin (oral and injection) against ivermectin-resistant strain of T. colubriformis in sheep. Reduction in arithmetic mean fecal egg counts achieved by ivermectin (oral), abamectin (oral) and abamectin (injection) was 66, 98 and 76%, respectively 10 days after treatment. Ivermectin (oral), abamectin (oral) and abamectin (injection) reduced arithmetic mean worm burden by 63, 97 and 74%, respectively. The findings demonstrated that abamectin oral formulation was more effective than abamectin injection against ivermectin-resistant strain of T. colubriformis in sheep.  相似文献   
87.
The objectives of this study were to describe the pharmacokinetics of firocoxib following oral (PO) dosing and intravenous (IV) injection in sows. Seven healthy sows were administered 0.5 mg firocoxib/kg IV. Following a 23-d washout period, sows were administered firocoxib at 4.0 mg firocoxib/kg PO. Blood samples were collected at predetermined times for 72 hr after IV and 120 hr after PO administration. Plasma firocoxib concentration was measured using UPLC-MS/MS, and pharmacokinetic analysis was performed using noncompartmental procedures. Tissue firocoxib concentrations were determined at 5, 10 (n = 2/time point), and 21 d (n = 3) after PO administration. The geometric mean half-life following IV and PO administration was 16.6 and 22.5 hr, respectively. A mean peak plasma concentration (Cmax) of 0.06 µg/ml was recorded at 7.41 hr (Tmax) after oral administration. Mean oral bioavailability was determined to be 70.3%. No signs of NSAID toxicity were observed on macroscopic and microscopic investigation. Firocoxib was detected in the skin with subcutaneous fat (0.02 µg/g) of one of three sows at 21 days postadministration. Additional work to establish appropriate meat withhold intervals in sows is required. Firocoxib was readily absorbed following PO administration. Further work is needed to better understand the analgesic effects for sows and piglets nursing sows administered firocoxib.  相似文献   
88.
The physical measurements and chemical analyses of date fruits of five cultivars grown in the United Arab Emirates were measured in this study. Due to differences in seed weight, the flesh accounted for 83–92% of the total fruit. At the tamr stage, the absence of sucrose and the presence of higher concentrations of reducing sugars, especially fructose and glucose, characterized these cultivars as the soft type. On maturation from the kimri to the tamr stage, the sugar content had increased, but other constituents like moisture, crude protein, crude fat, ash, crude fiber, tannins, and pectin had decreased.  相似文献   
89.
A doubled haploid (DH) population of 125lines derived from IR64 × Azucena, an indicajaponica cross were grown in three different locations in India during the wet season of 1995. The parents of mapping population had diverse phenotypic values for the eleven traits observed. The DH lines exhibited considerable amount of variation for all the traits. Transgressive segregants were observed. Interval analysis with threshold LOD > 3.00 detected a total of thirty four quantitative trait loci (QTL) for eleven traits across three locations. The maximum number of twenty QTL were detected at Punjab location of North India. A total of seven QTL were identified for panicle length followed by six QTL for plant height. Eight QTL were identified on three chromosomes which were common across locations. A maximum of seven QTL were identified for panicle length with the peak LOD score of 6.01 and variance of 26.80%. The major QTL for plant height was located on Chromosome 1 with peak LOD score of 16.06 flanked by RZ730-RZ801 markers. Plant height had the maximum number of common QTL across environment at the same marker interval. One QTL was identified for grain yield per plant and four QTL for thousand grain weight. Clustering of QTL for different traits at the same marker intervals was observed for plant height, panicle exsertion, panicle number, panicle length and biomass production. This suggests that pleiotropism and or tight linkage of different traits could be the plausible reason for the congruence of several QTL. Common QTL identified across locations and environment provide an excellent opportunity for selecting stable chromosomal regions contributing to yield and yield components to develop QTL introgressed lines that can be deployed in rice breeding program. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
90.
G. S. Sidhu  G. S. Khush 《Euphytica》1979,28(2):233-237
Summary Two-way classification of 400 F3 families from the rice cross IR2153-159-1 x Babawee for plant stature and for resistance to brown planthopper, green leafhopper, and bacterial blight indicated that Glh 3 (dominant gene for resistance to green leafhopper) and bph 4 (recessive gene for resistance to brown planthopper) are linked with a map distance of 34 units. The bph 4 gene also appears to be linked with sd 1 (recessive gene for semidwarf stature) although the linkage is less strong. However, bph 4 and Xa 4 (dominant gene for bacterial blight resistance) are inherited independently of each other. No segregation for susceptibility was observed among F3 families of crosses between varieties having Bph 3 and bph 4 genes for resistance to brown planthopper. Apparently, Bph 3 and bph 4 are either allelic or closely linked.  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