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   78篇
  免费   3篇
林业   3篇
农学   9篇
基础科学   1篇
  22篇
综合类   8篇
农作物   8篇
水产渔业   4篇
畜牧兽医   18篇
园艺   4篇
植物保护   4篇
  2023年   1篇
  2022年   2篇
  2021年   1篇
  2019年   5篇
  2018年   5篇
  2017年   1篇
  2016年   7篇
  2015年   6篇
  2014年   5篇
  2013年   7篇
  2012年   4篇
  2011年   10篇
  2010年   2篇
  2009年   7篇
  2008年   3篇
  2007年   2篇
  2006年   2篇
  2005年   2篇
  2004年   2篇
  2003年   1篇
  2002年   2篇
  2000年   1篇
  1997年   1篇
  1991年   1篇
  1978年   1篇
排序方式: 共有81条查询结果,搜索用时 312 毫秒
51.
Ali  Nawab  Anjum  Muhammad Mehran  Khan  Gul Roz  Ali  Rovaid 《Gesunde Pflanzen》2022,74(1):41-52

Water resources are increasingly scarce, and in drought prone production systems, the capability of the plant to recover its adverse effects is important for yield stability. There is an urgent need to develop water-saving strategies for wheat production. Water stress at critical growth stages diminishes wheat production and has harmful effects on crop growth and development; however, regulated water deficit and potassium foliar application ameliorates its adverse effect up to a certain extent. Consequently, the water deficit effect at different growth stages of the crop with exogenous application of potassium was evaluated in a screenhouse experiment in a complete randomized design (CRD) having four repeats. Varieties of wheat, i.e. Lalma (drought resistant) and Pakhtunkhwa-2015 (drought susceptible), were sown. Water deficit, i.e. mild water stress (50% of water required for field capacity) and severe stress (no application of water), at different growth stages of the crop were imposed. Potassium (K) foliar spray (1%) from potassium sulfate (K2SO4) was applied at the respective stage subjected to water deficit levels. Internal water status, i.e. relative water content (RWC) and water retention capacity (WRC), were attained maximum at tillering stage under mild stress than the rest of the stages with maximum for Lalma. Conversely, water saturation deficit (WSD) and water uptake capacity (WUC) were higher under severe stress imposed at grain filling stage. Theses indices were maintained by foliar potassium application. Similarly, dry matter (DM) allocation varied for stress level imposition and translocation to other parts were improved under foliar K application. The chlorophyll indices, i.e., soil plant analysis development (SPAD) value, also decreased with the severity of water deficit. Grain yield was higher under stress imposition at grain filling stage than the rest of the stages, though severe water stress decreased yield significantly. The Potassium (K) foliar spray showed no prominent effect at grain filling. Canopy temperature increased with stress severity and was maintained under K foliar spray. Osmotic adjustment, water and turgor potential were affected by water stress and maintained with foliar K spray. Grain quality and biochemical traits of wheat were affected severely under water deficit. Potassium foliar spray was found to decrease the adverse effect of the water stress and hence maintained the quality and biochemical characters. It is concluded that application of foliar potassium decreases the adverse effects of water stress at any growth stage, minimises the stress indices drastic effect and maintains the internal water balance of the crop at different stages subjected to water deficit.

  相似文献   
52.
Over the last few decades a dramatic decline in the number of Mediterranean monk seals (Monachus monachus) limited scientific studies on the biology, behaviour, and ecology of the species. This lack of information impaired the effectiveness of conservation strategies. Thus, any further information gathered on the monk seal has utmost value in the work to halt and reverse the plight of the species. A hitherto unknown Cilician Basin colony of the Mediterranean monk seal has been investigated during a 6-year period between 1995 and 2001. Results of direct in-cave surveys and land based seal-watch observations enabled the evaluation of habitat use and preliminary demographic information. A total of 39 caves were discovered among which only three were used for breeding. Scarcity of the breeding caves emphasised the importance of breeding habitat in the survival of the colony. Common features of the breeding caves are found as an entrance with a protective barrier against strong waves; a chamber with a wide beach; and a well-sheltered shallow pool. Supplementary data obtained from infrared monitors installed in three actively used caves were used to assess the number of individuals. Throughout the study period, 25 individuals were identified and 11 newborn pups were found. Evaluation of the results suggests the presence of sub-regions inhabited by an individually identified sub-group of monk seals. Recommendations for conservation guided by this information is a Marine Protected Area consisting of two zones; a restricted core zone prohibiting any human activity securing breeding habitat and a restricted fishery zone securing sustainability of the food source.  相似文献   
53.
M. Gul Hossain 《Euphytica》1978,27(1):137-143
Summary Aneuploidy was studied in populations selected for high seed-set with regular meiosis and low-seedset with irregular meiosis and an unselected population of the same origin. The frequency of aneuploids was significantly reduced in the high population that was characterised by increased bivalent frequency. In spite of a similar quadrivalent frequency in euploid plants of the low and the unselected population, the former population had a significantly higher frequency of aneuploids. However, there was no significant difference in the performance of aneuploid plants from the three populations. The results indicated that hyperaneuploid gametes were less functional than hypoaneuploid gametes but no significant difference was found in the performance of hypo- and hyperancuploids.  相似文献   
54.
Pregnancy toxemia is a metabolic disease of pregnant ewes which causes significant economic losses in sheep industry. The pathophysiology and metabolic changes of this disorder remain poorly understood. We conducted this study to describe the serum protein pattern associated with the pregnancy toxemia in ewes. In this study, the electrophoretic pattern of serum proteins of 15 ewes with naturally occuring pregnancy toxemia and 12 ewes with uncomplicated pregnant were investigated by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). Serum protein patterns were mainly characterized by four bands and located in the 76 kDa, 66 kDa, 55 kDa and 29 kDa both diseased and control groups. The percent of the 66 kDa, 55 kDa and 29 kDa proteins were decreased (P < 0.001 for 66 kDa; P < 0.01 for 55 kDa and P < 0.05 for 29 kDa) while 76 kDa (P < 0.05) protein was significantly increased (P < 0.001) in ewes with pregnancy toxemia relative to controls. Positive correlations were found between activities of liver enzymes and percentage of the distribution in 76 kDa, 55 kDa proteins. In contrast, there was a negative correlation between the 66 kDa protein and liver enzymes. In conclusion, the results of this study demonstrate that the percentages of the 76 kDa, 66 kDa, 55 kDa and 29 kDa proteins are significantly altered in ewes with pregnancy toxemia. However, further studies are needed to explore the potential role of these alterations in the pathophysiology in ewe with pregnancy toxemia.  相似文献   
55.
This study was carried out to determine serum protein profiles in naturally infected sheep with foot-and-mouth disease virus (FMDV). The study material consisted of twelve healthy and 36 sheep with foot-and-mouth disease (FMD). FMD had been diagnosed on the basis of clinical findings and results of serological examination. Serotypes serologically detected in the FMDV-infected sheep were as follows: O (n = 11), A (n = 8) and mixed infection with serotypes O, A and Asia-1 (n = 17).The total protein, albumin and globulin concentrations as well as Albumin/Globulin ratio were slightly different among the groups (P < 0.05). Three protein bands of 66 kDa, 45 kDa and 20 kDa were remarkable. Moderate differences were determined between healthy and infected sheep for proportion of distribution in serum proteins. In conclusion, serum protein concentrations and serum protein profiles were slightly changed and no specific serum protein profile occurred in sheep infected with either O or A or in sheep mixed infected with the O and A and Asia-1 serotypes of FMDV compared to healthy ones.  相似文献   
56.
The aim of this study was to determine the cardiotoxic potency of tulathromycin. Tulathromycin (10 mg/kg, SC) was administered to ten adult male rabbits, and blood samples were obtained before and after drug administration (0 and 6 hours). Serum cardiac damage markers (troponin I, creatine kinase-MB, myoglobin, lactate dehydrogenase, aspartate aminotransferase), routine serum biochemical values (alkaline phosphatase, alanine aminotransferase, gamma-glutamyltransferase, creatinine, blood urea nitrogen, cholesterol, triglyceride, high-density lipoprotein, amylase, total protein, albumin, glucose, calcium, ionised calcium, sodium, potassium), white blood cell (WBC) and red blood cell (RBC) counts, arterial blood gas parameters (pH, partial carbon dioxide pressure, partial oxygen pressure, actual bicarbonate, standard bicarbonate, total carbon dioxide, base excess in vivo, base excess in vitro, oxygen saturation, packed cell volume, haemoglobin) and serum oxidative status (malondialdehyde, nitric oxide, superoxide dismutase, retinol, β-carotene) were measured. Increased levels of troponin I, creatine kinase-MB and creatinine, and decreased WBC counts, ionised calcium and potassium levels were observed after drug administration. Tulathromycin treatment may cause cardiotoxicity, but its effects may be less dramatic than those of other macrolide antibiotics frequently used in veterinary medicine.  相似文献   
57.
Aroma and aroma-active compounds of wild grey mullet ( Mugil cephalus ) were analyzed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). According to sensory analysis, the aromatic extract obtained by simultaneous distillation and extraction (SDE) was representative of grey mullet odor. A total of 50 aroma compounds were identified and quantified in grey mullet. Aldehydes were qualitatively and quantitatively the most dominant volatiles in grey mullet. Aroma extract dilution analysis (AEDA) was used for the determination of aroma-active compounds of fish sample. A total of 29 aroma-active compounds were detected in aromatic extract of grey mullet, of which 24 were identified. On the basis of the flavor dilution (FD) factor, the most powerful aroma active compounds identified in the extract were (Z)-4-heptenal and nonanal, which were described as the strong cooked fish and green-fruity odor, respectively.  相似文献   
58.
Citrus, especially Kinnow, fruit yield and quality in Pakistan is not competitive with other countries, which could be mainly attributed to a lack of good nutrient management for citrus orchards. Many of the soils under these orchards have been reported as deficient in potassium (K). Therefore, work was initiated for improving citrus fruit yield, size, and quality through K nutrition management. Experiments were conducted in four districts of Punjab including Faisalabad, Toba Tek Singh, Jhang, and Sargodha and four rates of potash, i.e., 0, 50, 75 and 100 kg dipotassium oxide (K2O) ha?1 were applied using sulfate of potash (SOP) along with recommended rates of phosphorus (P) and nitrogen (N). Soils of all the selected sites were clay loam or sandy clay loam and deficient in K. The leaf analysis also showed that all the selected orchards were deficient in K. Application of K increased the fruit yield and quality but K at100 kg K2O ha?1 was more effective in increasing the fruit weight and size, and peel thickness than other K rates in all the selected orchards. Juice volume and percentage significantly increased when K was applied at 75 kg K2O ha?1 at all sites. Nutrient uptake like K, P, and N enhanced with the increase in K application rate, however, the highest calcium (Ca)+ magnesium (Mg) was recorded at 50 kg K2O ha?1. The results indicated that all rates of K application improved the fruit yield and quality and reduced fruit dropping, however, 75 kg K2O ha?1 rate was more effective as juice volume and percentage, total soluble solid (TSS)/acid ratio and nutrient uptake showed significant improvement.  相似文献   
59.
The aim of this study was to compare the clinical and histopathological effects of tripeptide copper complex (TCC) and two different doses of laser application (helium-neon laser, 1 and 3 J cm(-2)) on wound healing with untreated control wounds. Experimental wounds were created on a total of 24 New Zealand white rabbits and topical TCC or laser was applied for 28 days. The wounds were observed daily, and planimetry was performed on days 7, 14, 21 and 28 to measure the unhealed wound area and percentage of total wound healing. Biopsies were taken weekly to evaluate the inflammatory response and the level of neovascularization. The median time for the first observable granulation tissue was shorter (P < 0.05) in the low and high dose laser groups than in the control group (3 and 2.66 vs. 4.5 days), but was not different between the TCC and control groups (4.16 vs. 4.5 days). Filling of the open wound to skin level with granulation tissue was faster (P < 0.05) in the TCC and high dose laser groups than in the control group (14 and 16 vs. 25 days), but was not different between the low dose laser and control groups (23 vs. 25 days). The average time for healing was shorter (P < 0.05) in the TCC and high dose laser groups (29.8 and 30.2 vs. 34.6 days), but was not different between the low dose laser and control groups (33.8 vs. 34.6 days). Histopathologically, wound healing was characterized by a decrease in the neutrophil counts and an increase in neovascularization. The TCC and high dose laser groups had greater neutrophil and vessel counts than in the control group, suggesting a more beneficial effect for wound healing.  相似文献   
60.
Progesterone has neuroprotective effects including augmentation of myelination in the central and peripheral nervous system. This study was designed to determine if demyelinating lesions in the cerebellum resulting from canine distemper virus (CDV) infection are associated with progesterone levels. Progesterone was measured using radioimmunoassay in samples of the cerebellum, corpus callosum, medulla oblongata, parietal, frontal, temporal, and occipital cortices as well as cerebrospinal fluid (CSF) and plasma collected from ten CDV infected and six non-infected dogs. The cerebellum progesterone level was significantly different between CDV infected (0.66+/-0.09 ng/g) and control dogs (1.14+/-0.09 ng/g) (p<0.001); however, no difference was observed for the other CNS regions, plasma and CSF (p>0.05). The cerebellum progesterone level was also significantly different between acute (0.71+/-0.0 5 ng/g) and chronic cases (0.61+/-0.09 ng/g) (p<0.05). The CDV infected cerebella were also categorized histopathologically according to the severity of demyelinating lesions as mild (n=5), moderate (n=2), or severe (n=3) among which the cerebellum progesterone level was significantly different (p<0.05). Progesterone concentration was 0.71+/-0.05 ng/g in mild, 0.65+/-0.10 ng/g in moderate, and 0.56+/-0.07 ng/g in severe cases. In conclusion, progesterone concentration decreases in the cerebellum in CDV infection and the severity of demyelinating lesions is the greatest in cerebella with the lowest progesterone concentrations. The results suggest that local impairment of progesterone metabolism may be associated with the initiation and progression of cerebellar lesions in CDV infection.  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