全文获取类型
收费全文 | 599篇 |
免费 | 41篇 |
专业分类
林业 | 98篇 |
农学 | 25篇 |
基础科学 | 4篇 |
86篇 | |
综合类 | 19篇 |
农作物 | 30篇 |
水产渔业 | 65篇 |
畜牧兽医 | 265篇 |
园艺 | 5篇 |
植物保护 | 43篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 18篇 |
2020年 | 36篇 |
2019年 | 31篇 |
2018年 | 27篇 |
2017年 | 21篇 |
2016年 | 30篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 44篇 |
2012年 | 40篇 |
2011年 | 30篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 29篇 |
2007年 | 36篇 |
2006年 | 31篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 11篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有640条查询结果,搜索用时 468 毫秒
551.
552.
Mojtaba Moradi Isaac Karimi Shirin Ahmadi Layth J. Mohammed 《Reproduction in domestic animals》2020,55(9):1027-1043
The inclusion of antioxidants (AOXs) has been proposed in various protocols to conserve the normal physiology of spermatozoa during (cryo) preservation. The main aim of this review was to understand the necessity of AOXs inclusion in semen extenders of caprine and ovine semen samples and to decipher physico-chemical space of AOXs used in semen extenders till now. A total 27 full-text relevant articles were finally discussed here. This systematic review showed that the inclusion of AOXs may improve the success of semen cryopreservation although at least three studies could not support this finding. AOXs have been not added after assaying total antioxidant capacity of the sample of interest, and this is principal measurement bias of all papers. Furthermore, no rational dose–response curve and precise posology have been considered in comparable studies. Furthermore, new methodologies are requested to detect the oxidative status of semen specimens before AXOs fortification and new methodologies like imaging are also needed to detect various injuries of sperms during semen (cryo)preservation. Defining computational chemical and physical spaces of AOXs which used in semen (cryo)preservation would be an interdisciplinary effort to hasten deciphering epoch-making compounds. In conclusion, more in-depth analytical, toxicological and pharmacological methodologies should be pursued in supplementation or addition of AOXs during caprine and ovine semen (cryo)preservation after determining the oxidative status of semen samples. 相似文献
553.
Mayha Mohammed Ali Nor Elmadiena Adil Ali El Hussein Catherine Anne Muckle Linda Cole Elizabeth Wilkie Ketna Mistry Ann Perets 《Tropical animal health and production》2013,45(5):1113-1118
This study was undertaken to determine the antimicrobial resistance patterns of Salmonella enterica subspecies enterica recovered from human, food, water, and animal samples collected in Khartoum State, Sudan. A total of 64 Salmonella isolates belonging to 28 different serovars were tested for their susceptibility to 13 antimicrobial agents. The majority of isolates (98.4 %) were resistant to at least one antimicrobial agent. Isolates were frequently resistant to ampicillin (90.6 %), cephalexin (50.0 %), nalidixic acid (25.0 %), streptomycin (21.9 %), kanamycin (18.8 %), gentamicin (17.2 %), and co-trimoxazole and trimethoprim (12.5 %). The most common pattern of multiple drug resistance included resistance to ampicillin and cephalexin. Most isolates were sensitive to chloramphenicol (98.4 %), ciprofloxacin (93.8 %), and norfloxacin (90.6 %). Two chicken- and the two human-origin S. Kentucky isolates were resistant to both ciprofloxacin and norfloxacin. All S. Kentucky isolates and the one S. Rissen isolate demonstrated multi-drug resistance. The results indicate the significance of multi-drug-resistant Salmonella serovars isolated from chickens and other animals and foods as sources for multi-drug-resistant Salmonella in humans in Sudan. 相似文献
554.
Critical response time (time available to implement effective measures for epidemic control): Model building and evaluation 总被引:1,自引:0,他引:1 下载免费PDF全文
A. L. Rivas S. E. Tennenbaum J. P. Aparicio A. L. Hoogesteijn H. O. Mohammed C. Castillo-Chvez S. J. Schwager 《Canadian journal of veterinary research》2003,67(4):307-311
The time available to implement successful control measures against epidemics was estimated. Critical response time (CRT), defined as the time interval within which the number of epidemic cases remains stationary (so that interventions implemented within CRT may be the most effective or least costly), was assessed during the early epidemic phase, when the number of cases grows linearly over time. The CRT was calculated from data of the 2001 foot-and-mouth disease (FMD) epidemic that occurred in Uruguay. Significant regional CRT differences (ranging from 1.4 to 2.7 days) were observed. 相似文献
555.
Mohamed Ahmed Kandeil Alaa El‐deen H. Mohamed Mohammed Abdel Gabbar Rasha Rashad Ahmed Shimaa M. Ali 《Journal of animal physiology and animal nutrition》2019,103(5):1437-1446
The objective of this study was to determine the impact of ginger and/or thyme aqueous extracts administration on the growth rate, caecum activity, reproductive performance and semen quality of rabbits. A total of 24 V‐line male rabbits at the age of 12 weeks were divided randomly into four equal groups (6/each) until 24 weeks of age. Treatments were as follows: drinking fresh water and served as control (G1); drinking water supplemented with 100 mg/kg b. wt. of ginger aqueous extract (G2); drinking water supplemented with 50 mg/kg b. wt. of thyme aqueous extract (G3); drinking water supplemented with 100 mg/kg b. wt. of ginger aqueous extract plus 50 mg/kg b. wt. of thyme aqueous extract (G4). Administration of aqueous thyme extract with 50 mg/kg b. wt. improved (p < 0.001) feed intake and growth performance compared to control. The highest average daily gain (p < 0.001) was found for G3 rabbits followed by G4, G2 and G1 respectively. While the most efficient feed conversion ratio was found in G4. Group 3 and group 4 had significant (p < 0.05) positive effect on caecum pH, ammonia and TVFAs concentration. Data indicated that treated groups had hastened the age with heavier body weight, larger testicular size and higher testosterone level. Also, most semen characteristics (volume, progressive motility, sperm concentration and normal spermatozoa) were higher in treated groups compared with the control group. Furthermore, gathering of the spermatozoa in the lumen of the seminiferous tubules, expanded epithelial cells stature of the epididymis with stuffed lumens with sperms in treated groups. In conclusion, aqueous extracts of ginger and/or thyme can be used as a growth promoter for improving reproductive performance of V‐line male rabbits. 相似文献
556.
557.
Sandy cropland soils in NW Europe were found to contain unusually high organic‐carbon (OC) levels, and a link with their land‐use history has been suggested. This study's aim was to assess the discriminating power of physical and chemical fractionation procedures to yield information on soil‐organic‐matter (OM) stability for these soils. In relict‐ and cultivated‐heathland soils, much higher proportions of 6% NaOCl treatment–resistant but 10% HF–soluble OC (MOC) and N (32.2% and 29.9%) were measured compared to a set of “permanent"‐cropland soils without a history of heathland land use (11.9% and 8.5%). Also, the proportions of 6% NaOCl– and 10% HF treatment–resistant OC and N in the relict and cultivated heathlands (19.2% and 12.0%) were higher than in the permanent‐cropland soils (17.7% and 5.7%). Stepwise multiple linear‐regression yielded a significant relationship between the annual mineralization (g C [100 g OC]–1), soil OC (g C kg–1) content, and %MOC: Annual mineralization = 4.347 – 0.087 soil OC – 0.032 %MOC (R2 = 0.65). Combinations of incubation experiments for quantification of the labile soil OM pool with chemical fractionation may thus yield meaningful data for development of soil‐organic‐matter models with measurable pools, but their applicability will be limited to specific combinations of former land use with soil, climate, and current management. 相似文献
558.
559.
Rajesh K. Chauhan Mohammed Anwar Sukhmal Chand Dharani D. Patra 《Archives of Agronomy and Soil Science》2013,59(2):223-232
A field experiment was conducted for two years (2007–2008 and 2008–2009) to study the effect of different dates of planting for three menthol mint (Mentha arvensis) cultivars (Saksham, Kushal and Kosi; developed by Central Institute of Medicinal and Aromatic Plants, Lucknow, India) on herb yield, oil yield and oil quality. All the cultivars produced higher herb and oil yields when planted on 18 February, compared with cultivars planted on other dates in both years. Average herb yield for Saksham increased by 12.89, 30.66, 54.01 and 85.71%, average herb yield for Kushal increased by 15.09, 30.57, 71.69 and 104.91%, and average herb yield for Kosi increased by 32.48, 53.28, 87.23 and 109.49% when planted on 4 January, 19 January, 3 February and 18 February, respectively, over cultivars planted on 20 December. Among the cultivars, Kosi produced a higher herb yield than Saksham and Kushal planted on 18 February. Saksham, Kushal and Kosi produced ~89.39, 152.04 and 170.22% higher oil yield, when planted on 18 February over their respective planting date of 20 December. Maximum menthol content was recorded in cultivar Saksham when planted on 18 February and in Kushal and Kosi when planted on 4 March. 相似文献
560.
Kommoju Srinivasarao Basavaraj C. Viraktamath Arremsetty S. Hari Prasad Gouri S. Laha Mohammed I. Ahmed Podishetty Natarajkumar Kalidindi Sujatha Madamshetty Srinivas Prasad Manish Pandey Mugalodi S. Ramesha Chirravuri N. Neeraja Sena M. Balachandran Nallathigal S. Rani Balachandra Kemparaju Kolluru Madhan Mohan Venkata S. A. K. Sama Hajira Shaik Chintavaram Balachiranjeevi Karnati Pranathi Gajjala Ashok Reddy Maganti S. Madhav Raman M. Sundaram 《Plant Breeding》2013,132(6):586-594
IR 58025A is a very popular wild‐abortive cytoplasmic male sterile (WA‐CMS) line of rice and is extensively used for hybrid rice breeding. However, IR 58025A and many hybrids derived from it possess mild aroma (undesirable in some parts of India) and are highly susceptible to bacterial blight (BB) and blast diseases. To improve IR 58025A for BB and blast resistance, we have introgressed a major dominant gene conferring resistance against BB (i.e. Xa21) and blast (i.e. Pi54) into IR 58025B, the maintainer line of IR 58025A. An introgression line of Samba Mahsuri (i.e. SM2154) possessing Xa21 and Pi54 genes in homozygous condition and fine‐grain type was used as donor parent, and backcross breeding strategy was adopted for targeted introgression of the resistance genes. PCR‐based molecular markers tightly linked to Xa21 and Pi54 were used for selection of BB‐ and blast‐resistant lines, while closely linked markers were used for identification of backcross‐derived plants devoid of Rf4 and aroma. At BC2F5, four backcross‐derived lines possessing resistance against BB and blast, devoid of aroma, high yield, short plant stature, long‐slender grain type and with recurrent parent genome recovery ranging from 88.8% to 98.6% were selected and advanced for further evaluation. The improved versions of IR 58025B, viz. SB54‐11‐143‐9‐44‐5, SB54‐11‐143‐9‐44‐98, SB54‐11‐143‐9‐44‐111 and SB54‐11‐143‐9‐44‐171, behaved as perfect maintainers when test‐crossed with WA‐CMS lines. Agronomically superior lines of improved IR 58025B are being converted to CMS line through backcrossing for developing high‐yielding and biotic stress‐resistant rice hybrids. 相似文献