全文获取类型
收费全文 | 953篇 |
免费 | 48篇 |
国内免费 | 4篇 |
专业分类
林业 | 82篇 |
农学 | 47篇 |
118篇 | |
综合类 | 50篇 |
农作物 | 45篇 |
水产渔业 | 99篇 |
畜牧兽医 | 480篇 |
园艺 | 11篇 |
植物保护 | 73篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 29篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 28篇 |
2017年 | 23篇 |
2016年 | 24篇 |
2015年 | 33篇 |
2014年 | 22篇 |
2013年 | 61篇 |
2012年 | 40篇 |
2011年 | 60篇 |
2010年 | 26篇 |
2009年 | 27篇 |
2008年 | 63篇 |
2007年 | 62篇 |
2006年 | 54篇 |
2005年 | 76篇 |
2004年 | 46篇 |
2003年 | 53篇 |
2002年 | 30篇 |
2001年 | 39篇 |
2000年 | 31篇 |
1999年 | 25篇 |
1998年 | 12篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1971年 | 1篇 |
1970年 | 7篇 |
1969年 | 2篇 |
1967年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有1005条查询结果,搜索用时 15 毫秒
991.
GAO Rui-qing LI Xiao-ling NAOHIRO Kuroda ISAO Kobayashi Research Institute of Wood Industry Chinese Academy of Forestry Beijing P. R. China 《北京林业大学学报》2005,(Z1)
该文介绍了日本木材工业的产品结构以及木材干燥的现状和发展,并对人工林木材高频真空干燥(RFV)与其他干燥方法进行了比较.在日本80%以上的锯材用于建筑用材.日本目前人工林工业用材林树种主要是日本柳杉(Sugi)和日本扁柏(Hinoki),占全部人工林工业用材林的近80%.该文对日本木材干燥的全部干燥方法进行了介绍,着重介绍了人工林木材高频真空干燥的应用与发展现状、存在的问题、解决方案以及工业化应用前景. 相似文献
992.
Kitaura R Kitagawa S Kubota Y Kobayashi TC Kindo K Mita Y Matsuo A Kobayashi M Chang HC Ozawa TC Suzuki M Sakata M Takata M 《Science (New York, N.Y.)》2002,298(5602):2358-2361
We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O2 locate in the middle of nanochannels and form a one-dimensional ladder structure aligned to the host channel structure. The observed O-O stretching Raman band and magnetic susceptibilities are characteristic of the confined O2 molecules in one-dimensional nanochannels of CPL-1 (coordination polymer 1 with pillared layer structure). 相似文献
993.
Molecular metals normally require charge transfer between two different chemical species. We prepared crystals of [Ni(tmdt)2] (tmdt, trimethylenetetrathiafulvalenedithiolate) and carried out crystal structure analyses and resistivity measurements. The analyses and measurements revealed that these single-component molecular crystals are metallic from room temperature down to 0.6 kelvin. Ab initio molecular orbital calculations suggested that pi molecular orbitals form conduction bands. The compact molecular arrangement, intermolecular overlap integrals of the highest occupied and lowest unoccupied molecular orbitals, and tight-binding electronic band structure calculation revealed that [Ni(tmdt)2] is a three-dimensional synthetic metal composed of planar molecules. 相似文献
994.
Trienoic fatty acids and plant tolerance of high temperature 总被引:2,自引:0,他引:2
The chloroplast membrane of higher plants contains an unusually high concentration of trienoic fatty acids. Plants grown in colder temperatures have a higher content of trienoic fatty acids. Transgenic tobacco plants in which the gene encoding chloroplast omega-3 fatty acid desaturase, which synthesizes trienoic fatty acids, was silenced contained a lower level of trienoic fatty acids than wild-type plants and were better able to acclimate to higher temperatures. 相似文献
995.
L. L. Sanford R. S. Kobayashi K. L. Deahl S. L. Sinden 《American Journal of Potato Research》1997,74(1):15-21
A selection (8380-1) fromSolatium chacoense Bitter (2n=2x=24) accession PI 458310 that synthesizes the leptine glycoalkaloids was compared in growth chambers with tetraploid (2n=4x=48) genotypes derived from tissue culture of 8380-1 leaf expiants for plant growth habit, leaf glycoalkaloid content, and effect on the development of Colorado potato beetle [Leptinotarsa decemlineata (Say)] larvae. The plants of the 4x regenerant genotypes were more vigorous with larger, more oval shaped leaflets than 8380-1 plants. The leaf concentrations of leptines and total glycoalkaloids were significantly lower (about 34%) in the 4x genotypes than in 8380-1. The proportion of leptines in the total glycoalkaloid content was nearly the same (about 80%) in both ploidy groups. In leaf-disk feeding tests, the development of Colorado potato beetle neonate larvae was not significantly different for the 2x and 4x genotypes. Both groups significantly slowed development compared with development on cv. Kennebec leaf disks. The 8380-1 selection and a group of 4x 8380-1 regenerant genotypes are maintained in the Vegetable Laboratory, Beltsville Agricultural Research Center, Beltsville, MD 20705 and are available for distribution. 相似文献
996.
H. Takahashi Y. Kurose Y. Suzuki M. Kojima T. Yamaguchi Y. Yoshida M. Ogino K. Hodate Y. Azuma T. Sugino M. Kojima K. Kangawa Y. Hasegawa S. Kobayashi 《Domestic animal endocrinology》2009
The effect of energy balance on the growth hormone (GH) secretory responsiveness to growth hormone-releasing hormone (GHRH) has not been determined in ruminant animals. Therefore, we examined the effects of intravenous injections of 0, 3.3, and 6.6 μg ghrelin/kg body weight (BW), with and without GHRH at 0.25 μg/kg BW, on GH secretory responsiveness in both the fed and fasted sheep. The injections were carried out at 48 h (Fasting state) and 3 h (Satiety state) after feeding. Blood samples were taken every 10 minutes, from 30 minutes before to 120 minutes after the injection. Low (3.3 μg/kg BW) and high (6.6 μg/kg BW) doses of ghrelin stimulated GH secretion significantly (P < .05) greater in the Satiety state than in the Fasting state. Growth hormone-releasing hormone plus both doses of ghrelin stimulated GH secretion significantly (P < .05) greater in the Satiety state than in the Fasting state. Ghrelin and GHRH exerted a synergistic effect in the Satiety state, but not in the Fasting state. Plasma ghrelin levels were maintained significantly (P < .05) greater in the Fasting state than in the Satiety state except the temporal increases after ghrelin administration. Plasma free fatty acid (FFA) concentrations were significantly (P < .01) greater in the Fasting state than in the Satiety state. In conclusion, the present study has demonstrated for the first time that ghrelin differentially modulates GH secretory response to GHRH according to feeding states in ruminant animals. 相似文献
997.
Kobayashi K Yamamoto K Kikuyama S Machida T Kobayashi T 《Journal of toxicologic pathology》2009,22(3):187-194
Congenitally primary hypothyroid growth-retarded (grt) mice exhibit a characteristic growth pause followed by delayed onset of pubertal growth. We characterized the developmental pattern of somatotropes, lactotropes and thyrotropes in the anterior pituitary, as well as plasma levels of their secretory hormones, in grt mice. Compared with normal mice, the weight of grt pituitary gland was similar at 8 weeks of age but significantly heavier after 12 weeks of age. Compared with normal mice, there were significantly fewer somatotropes in the grt pituitary until 8 weeks of age, but the number gradually increased up to 48 weeks. The number of lactotropes in grt mice was consistently lower than that in normal mice from 2 through 48 weeks, whereas the number of thyrotropes in the grt pituitary was consistently higher than in the normal pituitary. Thyrotropes in the grt pituitary exhibited hypertrophy and hyperplasia with less intensive thyroid-stimulating hormone (TSH) immunoreactivity than normal thyrotropes. In normal mice, the sum of the relative proportions of these cells plateaued at 8 weeks, where it remained up to 48 weeks of age. In grt mice, these proportions almost reached normal levels at 12 weeks of age but gradually declined after 24 weeks. Plasma growth hormone concentrations did not differ between grt and normal mice until 24 weeks of age. Compared with normal mice, grt mice exhibited significantly lower plasma prolactin and thyroxine levels but higher TSH levels. These findings indicate that development of somatotropes, lactotropes and thyrotropes in grt mice is impaired, being followed by altered hormone secretion. 相似文献
998.
Oestrus detection error and conception rates after AI based only on secondary oestrus signs were evaluated in a high yielding, 24-h tie-stalled dairy herd with low fertility, using milk progesterone profiles. Oestrus detection was based on the secondary oestrus signs such as restlessness, swelling, congestion of vulva and clear mucus discharge. Sixty eight AI conducted after observing the secondary oestrus signs in 44 animals were included in the study. Of the 68 AI, 53 (77.9%) were conducted in the follicular phase, and 13 (19.1%) and 2 (2.9%) were carried out in the luteal phase and during pregnancy, respectively. The overall error in oestrus detection based on milk progesterone profiles was 22.1%. The oestrus detection error did not differ significantly among different secondary oestrus signs. None of the AI conducted in the luteal phase resulted in conception, whereas 20.8% of AI conducted in the follicular phase resulted in conception. No significant difference in the conception rates among the groups of cows with different secondary oestrus signs was shown. The high incidence of oestrus detection error in this study might have been caused by the detection of cows in oestrus based only on secondary oestrus signs due to the confinement of animals. In conclusion, there was a high incidence of heat detection error in the 24-h tie-stalled dairy herd and oestrus detection based only on secondary oestrus signs resulted in low conception rate. 相似文献
999.
Jihye Shin Mi Ae Kim Makito Kobayashi Young Chang Sohn 《Fish physiology and biochemistry》2013,39(5):1353-1363
Thyrotropin (thyroid-stimulating hormone, TSH), a heterodimeric glycoprotein hormone produced in the pituitary, stimulates the thyroid gland and release of thyroid hormones. In contrast to a well-known efficacy of recombinant mammalian TSHs, there is no report about the production of teleost recombinant TSH and its biological activity. In this study, we report the production of a single-chain recombinant TSH (mtTSH) of Manchurian trout (Brachymystax lenok), by baculovirus in silkworm (Bombyx mori) larvae. The mtTSH was produced in silkworm larvae and characterized as a form of N-linked glycosylation. The cAMP signaling system in transiently transfected COS-7 cells revealed that the mtTSH was recognized by their cognate receptors, salmon TSHα and TSHβ receptors, but not LH receptor. The thyrotropic potency of the mtTSH was examined by rainbow trout basibranchial tissues containing thyroid follicles. The height of follicle epithelial cells was significantly increased by treatments of mtTSH in vivo and in vitro. In conclusion, the present study suggests that the mtTSH produced by baculovirus–silkworm larvae is a biologically active recombinant TSH. 相似文献
1000.
Kakinuma Makoto Ikeda Masaki Coury Daniel A. Tominaga Hiroshi Kobayashi Issei Amano Hideomi 《Fisheries Science》2009,75(4):1015-1028
We isolated two different genomic DNAs (UprbcS1 and UprbcS2) encoding the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase and portions of the 5′- and 3′-flanking regions
from sterile Ulva pertusa Kjellman. The UprbcS1 and UprbcS2 genes had three introns in the coding region. Each predicted UprbcS polypeptide was a 180-amino-acid (AA) residue including
a 38-AA transit peptide, although the 104th AA residue was replaced. The nucleotide sequences of UprbcS cDNAs isolated from a cDNA library corresponded to that of the UprbcS1 gene, suggesting that the UprbcS1 gene was predominantly expressed in sterile U. pertusa compared to UprbcS2. Southern blot analysis showed that each UprbcS gene was a single-copy gene in the sterile U. pertusa genome. Northern hybridization indicated that the expression of UprbcS was induced and repressed by dark and light treatments, respectively. When sterile U. pertusa cells were transformed with an expression vector containing the UprbcS1 promoter and terminator sequences fused with the green fluorescent protein (GFP) gene, GFP fluorescence was observed in the cells transformed. These results suggest that the UprbcS1 gene promoter is light regulated and highly active in the sterile U. pertusa cells and is available for genetic transformation system in the alga. 相似文献