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   273篇
  免费   6篇
  国内免费   2篇
林业   15篇
农学   28篇
  18篇
综合类   3篇
农作物   12篇
水产渔业   13篇
畜牧兽医   170篇
园艺   6篇
植物保护   16篇
  2022年   3篇
  2021年   7篇
  2020年   3篇
  2019年   3篇
  2018年   2篇
  2017年   2篇
  2016年   2篇
  2015年   10篇
  2014年   10篇
  2013年   14篇
  2012年   15篇
  2011年   20篇
  2010年   4篇
  2009年   7篇
  2008年   16篇
  2007年   28篇
  2006年   26篇
  2005年   20篇
  2004年   19篇
  2003年   12篇
  2002年   20篇
  2001年   6篇
  2000年   3篇
  1999年   6篇
  1998年   6篇
  1997年   3篇
  1996年   5篇
  1995年   3篇
  1992年   3篇
  1991年   1篇
  1987年   1篇
  1982年   1篇
排序方式: 共有281条查询结果,搜索用时 15 毫秒
91.
We investigated a non‐invasive method of specimen collection for determining the changes of reproductive hormones in aged menopausal monkeys after a long‐term feeding of the Thai herb Pueraria mirifica (PM) containing phytoestrogens. Three groups of aged menopausal monkeys (n = three in each group) were fed daily with 10, 100, or 1000 mg of PM for a 90 day treatment period, and fed with distilled water for 30 and 60 days of the pre‐ and post‐treatment periods, respectively. Urine samples were collected for 14 h daily every 5 days and assayed for follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol levels. The result showed that monkeys fed with PM 10, PM 100, and PM 1000 had a decrease in urinary FSH levels during the treatment period, followed by a rebound increase during the post‐treatment period. Urinary estradiol levels tended to decrease and fluctuated between 4.28 and 266.71, 2.85–42.27, and 6.24–203.50% of the pre‐treatment levels in those three groups, respectively. Decreases in urinary LH levels could not be observed in all the three groups. These results suggest that FSH could be a candidate marker to detect the estrogenic effects of phytoestrogens in aged menopausal monkeys when changes of urinary hormones need to be used as an indicator.  相似文献   
92.
REASONS FOR PERFORMING STUDY: Overstrain injuries to the superficial digital flexor tendon (SDFT) and suspensory ligament (SI) are among the most common musculoskeletal injuries which contribute to the considerable wastage of racing Thoroughbreds. Many epidemiological studies have demonstrated the prevalence of and risk factors for tendon injury when racing but have not included those injuries sustained during training. However, since tendon injury during training is seen commonly in clinical practice, it is appropriate to determine the overall prevalence of tendon injury sustained during both training and racing. OBJECTIVE: To determine the prevalence of overstrain injury to the SDFT and SL during training and racing among Thoroughbred flat racehorses in Japan in 1999. METHODS: A retrospective study was performed using a sample population of 10,262 Thoroughbred racehorses. The medical information database of Thoroughbred racehorses registered by the Japan Racing Association (JRA) in 1999 was analysed for SDFT and SL overstrain injury diagnosed by a veterinarian employed by JRA during training and racing. Jump racehorses were excluded from this study. RESULTS: The prevalence of forelimb SDFT tendonitis and SL desmitis was 11.1% (1130 cases) and 3.61% (370 cases) of the population, respectively. In the hindlimb, there were 0.06% (6 cases) and 0.14% (14 cases), respectively. Risks of SDF tendonitis in the forelimb in 3-year-olds or older horses were significantly higher than in 2-year-olds. In contrast, the risk of SL desmitis in the forelimb at age 3 and 4 years was 2.23 and 2.11 times higher, respectively, than in 2-year-olds, but this increased to 5.07 times in those age > or = 5 years. Entire males were at greater risk in comparison to females and geldings. CONCLUSIONS: The results suggest that the prevalence of SDF tendonitis and SL desmitis in the forelimb was associated with the horse's age and sex. The prevalence of SL desmitis increased further with age compared with SDF tendonitis, possibly reflecting a more rapid accumulation of degeneration in this structure. POTENTIAL RELEVANCE: The age-related risk demonstrated in this study provides further support that overstrain injuries are associated with accumulated degeneration. These data provide a valuable resource for further research into the aetiology of tendon injury in the racehorse.  相似文献   
93.
One hundred accessions of 18 wild diploid potato species were screened for resistance to scab through three cycles of selection, from which a total of 322 clones were selected as resistant. The putative ancestral species of the cultivated potatoes (Solanum bukasovii, S. canasense andS. multidissectum) produced resistant clones with significantly higher rates. Thus, these are primary gene sources for conferring scab resistance to cultivated potatoes.  相似文献   
94.
95.
With the aim of sharing information about the technical aspects of immunohistochemistry (IHC) and facilitating the selection of suitable antibodies for histopathological examination, this technical report describes the results of a questionnaire distributed during the period of 2018 to 2019 among members of the Conference on Experimental Animal Histopathology. Additionally, it describes the immunological properties and supplier details (clone, supplier, catalog number, species reactivity, etc.) as well as the IHC staining conditions (fixing solution, fixing time, embedding, antigen retrieval method, antibody dilution, incubation time, incubation temperature, positive control tissue, blocking condition, secondary antibody information, etc.) for a total of 509 primary antibodies (comprising 220 different types). These survey results were an update on the contents reported by CEAH in 2017.  相似文献   
96.
Solanum stenotomum Juz. et Buk. (2n = 2x = 24) is considered to be the most primitive diploid cultivated species from which all the other Andean cultivated potatoes were originated (Hawkes 1990). To disclose chloroplast DNA (ctDNA) variability and the maternal origin of S. stenotomum, 36 accessions of S. stenotomum and 86 accessions of putative wild ancestral species were determined for ctDNA types and analyzed by high-resolution markers (seven ctDNA microsatellites and an H3 marker). High-resolution markers discriminated 57 different ctDNAs (haplotypes), which were classified into the W-type ctDNA group and C-, S- and A-type ctDNA group, and within the latter group S- and A-type ctDNAs were distinct from each other among many different haplotypes mostly having C-type ctDNA. This ctDNA relationship supported our previous findings obtained for mostly Andean cultivated species (Sukhotu et al. 2004). Compared with other putative ancestral wild species, S. stenotomum showed somewhat limited ctDNA diversity, having two major haplotypes 1 and 2 also found in different wild species in different places. Therefore, the ctDNA in S. stenotomum was of at least dual origins either by successive domestication from different species or else by introgression after initial S. stenotomum arose.  相似文献   
97.
Resistance to net blotch was evaluated in 175 Hordeum vulgare subsp. spontaneum (H. spontaneum) accessions and 149 accessions of thirteen species or subspecies of wild Hordeum. Most H. spontaneum accessions showed resistance to each of the four Pyrenophora teres f. teres (P. teres) isolates tested. However, H. spontaneum accessions showed different resistance reactions, depending upon their origin. In particular, some accessions from Afghanistan and Russia showed a high level of resistance, and accessions from Morocco were susceptible. Among the four P. teres isolates, the virulence spectra on the H. spontaneum accessions were more different between isolates from different countries than between those from the same country. Hordeum spontaneum accessions susceptible to the Canadian isolate WRS102, but resistant to the other three isolates were found in Iraq suggesting the geographical differentiation of resistance genes in H. spontaneum. All accessions of the other wild Hordeum species, especially some accessions of H. marinum subsp. gussoneanum, showed high levels of resistance. These resistance genes may be useful candidates for incorporation into cultivated barley. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
98.
We developed a simple, easy method with a microplate to artificially incubate Japanese crayfish (Cambaroides japonicus) eggs for their cultivation. We prepared 6-, 12-, 24-, 48-, and 96-well microplates containing sterile water heated to 5, 10, 15, and 20 °C. Fourteen experimental groups for each water temperature were prepared for each of different water volumes (0.125–10 ml) in each well. One embryonic egg was placed in each well. Experiments were also conducted with water collected from the lake where the eggs were harvested from and held at 15 °C. In the microplates with sterile water, high proportions of eggs hatched (60–100%) at 15 °C in all volumes of water, although the proportions of hatching were low (0–20%) at 5, 10, and 20 °C. All eggs died in the experiments that used lake water. We conclude that the 96-well would be the most effective size to hatch crayfish eggs in, because of its convenience. This method using a microplate is simpler and easier compared with methods of previous studies to artificially incubate crayfish eggs, and therefore it might be useful to incubate eggs of other freshwater crayfish species.  相似文献   
99.
100.
The inheritance of the leaf pubescence character of a Chinese local wheat cultivar ‘Hon-mang-mai’ was investigated by monosomic and telosomic analyses. Leaf pubescence was evaluated by observation of the adaxial side of the penultimate leaf of adult plants. F1 hybrids of ‘Hong-mang-mai’ with a non-pubescent cultivar ‘Chinese Spring’ had leaf pubescence, but its density was about a half of that of ‘Hong-mang-mai’. In the F2 generation, the segregation ratio of pubescent to non-pubescent plants fitted a ratio of 3: 1, suggesting that leaf pubescence was controlled by one dominant gene. Monosomic analysis revealed that the gene for pubescence is located on chromosome 7B. Telosomic analysis showed that the gene is located on the short arm of chromosome 7B with a distance of 14.3%from the centromere. This gene is not allelic with the previously reported hairy leaf gene Hl on chromosome 4B, and therefore, is designated Hl2, hairy leaf 2. This revised version was published online in July 2006 with corrections to the Cover Date.  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