全文获取类型
收费全文 | 272篇 |
免费 | 7篇 |
专业分类
林业 | 14篇 |
农学 | 14篇 |
63篇 | |
综合类 | 23篇 |
农作物 | 9篇 |
水产渔业 | 16篇 |
畜牧兽医 | 90篇 |
园艺 | 4篇 |
植物保护 | 46篇 |
出版年
2022年 | 1篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 18篇 |
2012年 | 13篇 |
2011年 | 22篇 |
2010年 | 3篇 |
2009年 | 21篇 |
2008年 | 20篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 25篇 |
2004年 | 14篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有279条查询结果,搜索用时 31 毫秒
91.
Takayuki Ishikawa Tomoko Takayama Hiroshi Ishizaka Keiko Ishikawa Masahiro Mii 《Euphytica》2001,118(1):19-27
Interspecific hybrids were efficiently produced in the cross-incompatible combination between Alstroemeria pelegrina L. var. rosea and A. magenta Bayer by culturing immature ovules with placenta 7–14 days after pollination on 2 g/l Gelrite-solidified MS medium containing
3% (w/v)sucrose. The plants showed intermediate characteristics between the parents and their hybridity was confirmed by karyotype
and DNA analyses. The mean number of chromosome association per PMC at metaphase I was 2.60I+6.70II, pollen stainability was20.8%,
and they produced viable seeds after self-pollination. Furthermore, mature plants were obtained when the hybrids were backcrossed
as male parents with both the parents. The backcross-progeny from A. pelegrina var. rosea × hybrids exhibited 3.8 to 79.7% pollen stainability and that from A. magenta × hybrids 78.8 to 98.3%. Almost all of these plants produced viable seeds after self-pollination, which implies that they
can beutilized for breeding of novel cultivars of Alstroemeria.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
92.
93.
The development of rare earth element-labelled potassium-depleted clays for use as cohesive sediment tracers in aquatic environments 总被引:2,自引:1,他引:1
Purpose
Understanding the transport behaviour of fine cohesive sediment is fundamental to the sustainable management of aquatic environments. Sediment tracing techniques are widely used for measuring the transport pathways of sand-sized material in the field. However, the development of tracers, including geochemically labelled clays, for fine, cohesive sediment is more problematic. Such tracers should have chemical signatures that can be easily detected following significant dilution in the field and should remain constant for the duration of the tracer study.Materials and methods
We have examined the potential of rare earth element (REE)-labelled phlogopite and hydrobiotite as cohesive sediment tracers. Clays were first treated with sodium tetraphenylborate to extract interlayer potassium and enhance their cation exchange capacity. Ho, La and Sm were then sorbed to the clays in batch experiments. Desorption of the chemical signature in both fresh and saline conditions was examined after 1 and 10 days.Results and discussion
Potassium extraction enhanced REE sorption, resulting in REE concentrations in excess of 40,000 mg kg?1 in the labelled clays, and these signatures should be easily detected following dilution in the aquatic environment. In both fresh and saline conditions, over 90% of the tracer signature was retained over a 1-day period. However, over longer time scales, there was considerable loss of the REE signature.Conclusions
Over short time scales, there is considerable potential to use these materials as cohesive sediment tracers. Over longer time scales, although much of the label is lost, the tracers could still provide qualitative information identifying net sediment transport pathways. 相似文献94.
Yasuda A Natsume M Osakabe N Kawahata K Koga J 《Journal of agricultural and food chemistry》2011,59(4):1470-1476
Cocoa powder is rich in polyphenols, such as catechins and procyanidins, and has been shown to inhibit low-density lipoprotein (LDL) oxidation and atherogenesis in a variety of models. Human studies have also shown daily intake of cocoa increases plasma high-density lipoprotein (HDL) and decreases LDL levels. However, the mechanisms responsible for these effects of cocoa on cholesterol metabolism have yet to be fully elucidated. The present study investigated the effects of cacao polyphenols on the production of apolipoproteins A1 and B in human hepatoma HepG2 and intestinal Caco2 cell lines. The cultured HepG2 cells or Caco2 cells were incubated for 24 h in the presence of cacao polyphenols such as (-)-epicatechin, (+)-catechin, procyanidin B2, procyanidin C1, and cinnamtannin A2. The concentration of apolipoproteins in the cell culture media was quantified using an enzyme-linked immunoassay, and the mRNA expression was quantified by RT-PCR. Cacao polyphenols increased apolipoprotein A1 protein levels and mRNA expression, even though apolipoprotein B protein and the mRNA expression were slightly decreased in both HepG2 cells and Caco2 cells. In addition, cacao polyphenols increased sterol regulatory element binding proteins (SREBPs) and activated LDL receptors in HepG2 cells. These results suggest that cacao polyphenols may increase the production of mature form SREBPs and LDL receptor activity, thereby increasing ApoA1 and decreasing ApoB levels. These results elucidate a novel mechanism by which HDL cholesterol levels become elevated with daily cocoa intake. 相似文献
95.
Staphylococcus intermedius isolates (n=106), including 44 dog isolates and 62 pigeon isolates, were examined for their susceptibility to ampicillin, cephalexin, erythromycin, gentamicin, kanamycin, lincomycin, norfloxacin, oxacillin, tetracycline, and vancomycin by standard disk-diffusion test. The frequencies of resistance to ampicillin, kanamycin, and tetracycline were significantly higher in dog isolates than pigeon isolates (95.5% vs. 0%, 31.8% vs. 0%, and 45.5% vs. 9.7%, respectively; P<0.01). Antimicrobial resistance patterns of dog isolates and pigeon isolates were categorized respectively into nine and five distinct profiles. Significantly higher occurrence of resistance to two or more antimicrobials was observed in dog isolates than pigeon isolates (54.5% vs. 12.9%; P<0.01) and also in domesticated pigeon isolates than non-domesticated pigeon isolates (53.3% vs. 0%; P<0.01). 相似文献
96.
Rieko OKAME Keiko NAKAHARA Yumiko KATO Makoto BANNAI Noboru MURAKAMI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(6):661-668
It has been suspected that in comparison with glucose or fatty acids, the levels of amino
acids may readily change with different forms of exercise. In the present study, we
measured the concentrations of amino acids, glucose, triglycerides, total protein and
total cholesterol in the blood and/or cerebrospinal fluid (CSF) of rats subjected to
forced running exercise on a treadmill, and voluntary running exercise using a wheel, with
a constant running distance of 440 m. Rats that performed no running and rats subjected to
immobilization stress were used as controls. We observed a few significant changes in the
levels of plasma glucose, triglycerides, total protein and total cholesterol in all
groups. Whereas, plasma amino acid levels were significantly changed by exercise and
stress, especially during the light period. The plasma levels of many amino acids were
specifically increased by forced running; some were decreased by immobilization stress.
Few amino acids showed similar changes in their levels as a result of voluntary running.
In addition, there was a significant difference in the degree of amino acid imbalance
between blood and CSF. These results provide the first information on changes in levels of
amino acids in plasma and CSF resulting from forced and voluntary exercises. 相似文献
97.
Jatindra N. Bhakta Y. Munekage K. Ohnishi B. B. Jana J. L. Balcazar 《Water, air, and soil pollution》2014,225(10):1-10
The contamination of hazardous metal(loid) is one of the serious environmental and human health risks. This study isolated a total of 40 cadmium (Cd)- and arsenic (As)-resistant bacterial isolates from coastal sediments by pour plate technique using tryptic soy agar supplemented with Cd or As (50 mg l?1) for use as metal(loid) bioremediation agents. Out of 40, 4 isolates, RCd3, RCd6, RAs7, and RAs10, showed a relatively higher growth rate in Cd- or As-supplemented culture media which were selected for further study. The selected isolates showed a high minimum inhibitory concentration (60–400 mg l?1 for Cd and 400–2200 mg l?1 for As), which demonstrated their remarkable Cd and As resistance capabilities. The metal(loid) removal efficiencies (0.032–0.268 μg Cd h?1 mg?1 and 0.0003–0.0172 μg As h?1 mg?1 [wet weight cell]) of selected isolates indicated their greater magnitude in absorbing Cd compared to As from water. Phylogenetic analysis of the 16S rDNA sequences revealed that isolates RCd3, RCd6, RAs7, and RAs10 were closely related to Acinetobacter brisouii, Pseudomonas abietaniphila, Exiguobacterium aestuarii, and Planococcus rifietoensis, respectively. Because of high Cd and As resistance and removal efficiency, the selected isolates can survive in a high metal(loid)-contaminated environment and could be a potential tool for bioremediation of high metal(loid)-contaminated effluents to protect the aquatic environment. 相似文献
98.
99.
100.
Ishikawa H Matsui T Ohtsu T Watanabe K Matsumoto K Matsumoto K 《Journal of agricultural and food chemistry》2005,53(9):3488-3492
Sorption of ionizable compounds of pyridines and aromatic carboxylic acids into low-density polyethylene (LDPE) film was investigated as a function of pH ranging from 4 to 7. The sorptions for pyridines were increased with increasing pH. Within the range examined, pH 7 was observed to promote the highest degree of sorption. When the pH increased by one unit from 6 to 7, the sorptions for 2-propylpyridine and 2,4,6-trimethylpyridine were both increased approximately 3.8 and 10.5 times, respectively. At pH 4, the sorption for the pyridines entirely disappeared. In contrast, the sorptions for aromatic carboxylic acids increased with decreasing pH. Within the range examined, pH 4 was observed to promote the highest degree of sorption. The magnitude of sorption for pyridines and carboxylic acids apparently depended on the affinity (delta(c)) of these compounds for LDPE film. Another factor affecting the sorption at various pHs was the pK(a) of these compounds; the sorption greatly decreased with the ionization degree of these compounds. To elucidate the phenomena, the following thermodynamic sorption equation was applied: S = S(0)gamma exp[V(v){(delta(w) - delta(v))(2) - delta(c)(2))/RT}. The plots of ln S for pyridines vs the term of the equation gave an insufficient relationship (r = 0.519). In contrast, taking into account the ratio (chi(i)()) of concentration of un-ionized compound to total concentration, the improvement for the equation was made: S' = S/chi(i)() = S(0)gamma exp[V(v){(delta(w) - delta(v))(2) - delta(c)(2))/RT}. The plots of ln S' vs the term of the equation gave a better relationship (r = 0.884). Furthermore, the equation was also applicable for the sorption behavior of carboxylic acids into LDPE (r = 0.769). 相似文献