全文获取类型
收费全文 | 938篇 |
免费 | 27篇 |
国内免费 | 2篇 |
专业分类
林业 | 129篇 |
农学 | 33篇 |
基础科学 | 1篇 |
113篇 | |
综合类 | 40篇 |
农作物 | 54篇 |
水产渔业 | 174篇 |
畜牧兽医 | 341篇 |
园艺 | 12篇 |
植物保护 | 70篇 |
出版年
2023年 | 2篇 |
2022年 | 18篇 |
2021年 | 50篇 |
2020年 | 21篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 24篇 |
2016年 | 29篇 |
2015年 | 28篇 |
2014年 | 51篇 |
2013年 | 58篇 |
2012年 | 50篇 |
2011年 | 63篇 |
2010年 | 31篇 |
2009年 | 37篇 |
2008年 | 59篇 |
2007年 | 54篇 |
2006年 | 57篇 |
2005年 | 49篇 |
2004年 | 49篇 |
2003年 | 61篇 |
2002年 | 43篇 |
2001年 | 38篇 |
2000年 | 21篇 |
1999年 | 10篇 |
1998年 | 13篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1980年 | 2篇 |
排序方式: 共有967条查询结果,搜索用时 15 毫秒
851.
Composition of acidic components in Chinese raw tall oil 总被引:1,自引:0,他引:1
Shi-Fa Wang Takeshi Furuno Zhi Cheng Tohru Uehara Sadanobu Katoh 《Journal of Wood Science》2000,46(3):258-262
Chinese raw tall oil samples, which were obtained from pulp and papermaking factories in Qingzhou and Jiamusi, were first divided into acidic and neutral parts with a diethylaminoethyl-Sephadex (DEAE-Sephadex) gel column. The acidic components were then analyzed qualitatively and quantitatively by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The results obtained are as follows: Most of the compounds that comprised 0.1% or more of the components were identified. Secodehydroabietic, 8,15-pimaradienoic, 8,15-isopimaradienoic, 7,13,15-abietatrien-18-oic acid, and others were found for the first time in Chinese tall oil; they have not been found in Chinese fatty rosin. Docosan-1,22-dioic acid was also found in tall oil for the first time. 相似文献
852.
The mode of action of soluble silicon against strawberry powdery mildew (Sphaerotheca aphanis var. aphanis) was investigated in four experiments. First, silicon-treated leaves from plants grown with silicate (Si+) and control leaves
were excised, inoculated with conidia, and subsequent germination and formation of appressoria in a petri dish was assessed
after 24 h. The germination rate was 49.7% on Si+ leaves, and was 67.2% on control leaves (t-test, P < 0.01). Second, we soaked cellulose membranes in various solvents and then placed the membranes on 4% water agar, dusted
the membranes with conidia, and examined after 12 h. No difference was apparent between any treatment and the control (distilled
water). Third, strawberries growing hydroponically with additional silicon in the medium were inoculated with conidia, and
leaves were observed with a scanning electron microscope 1–2 days after inoculation. Germ tubes and secondary hyphae were
shorter and had fewer branches on Si+ leaves than on the control. Moreover, penetration appeared to be inhibited. Fourth,
the cuticle was separated from leaves from plants grown as in the third experiment, placed on water agar, and dusted with
conidia. Germination of conidia, observed with a light microscope, on Si+ leaves was suppressed markedly to 40%–60% of that
of the control. These results suggested that soluble silicon induced physiological changes in the cuticle layer after absorption
by the plant. In addition, soluble silicate reduced germination of conidia, formation of appressoria, and possibly the penetration
of powdery mildew. 相似文献
853.
Takeshi Toda Toshihiro Hayakawa Joseph Mwafaida Mghalu Shigeharu Yaguchi Mitsuro Hyakumachi 《Journal of General Plant Pathology》2007,73(6):379-387
Isolates of an unidentified Rhizoctonia sp. (UR isolates) were obtained from creeping bentgrass and Kentucky bluegrass with reddish brown sheath and foliar rots.
Because the UR isolates anastomosed with isolates of three varieties of Waitea circinata (var. oryzae, var. zeae, and var. circinata), colony morphology, hyphal growth rate at different temperatures, pathogenicity, sequence analysis of the internal transcribed
spacers (ITS) region of ribosomal RNA genes (rDNA) were compared. The colony color of mature UR isolates was distinct from
isolates of the other three varieties of W. circinata. In pathogenicity tests on creeping bentgrass, the severity of the disease caused by UR isolates was significantly higher
than that caused by the three varieties of W. circinata. Sequence similarities of the rDNA-ITS region between UR isolates and between isolates within each variety were high (97–100%),
but they were lower among isolates from UR and the varieties of W. circinata (88–94%). In a phylogenetic tree based on the rDNA-ITS sequences, UR isolates formed a cluster separate from each of the
clusters formed by the three varieties of W. circinata. These results indicate that the UR isolates clearly differ from the three varieties of W. circinata. We therefore propose that the UR isolates be classified as new Rhizoctonia sp. that are closely related to W.
circinata and that the disease on creeping bentgrass should be called Waitea reddish-brown patch disease (Sekikasshoku-hagusare-byo
in Japanese). 相似文献
854.
Michiaki Iwata Kenji Umemura Takeshi Teraoka Hideki Usami Yukiko Fujisawa Yukimoto Iwasaki 《Journal of General Plant Pathology》2003,69(1):83-86
Certain cellular responses to stresses and stimuli are regulated by a G-protein-mediated signaling pathway. A rice dwarf
mutant that is defective in the α subunit of the heterotrimeric G-protein was found to be fully protected from blast fungus
by the plant activator probenazole (PBZ) despite the 1-day delay in induction of the PR-10 gene PBZ1 by PBZ. These results suggest that the signaling pathway for protection by PBZ is not via the G-protein, although G-protein
is involved in the induction of PBZ1 by PBZ.
Received: March 27, 2002 / Accepted: August 20, 2002 相似文献
855.
An avian pathogenic Escherichia coli strain M1000 showed a clear zone of erythrocyte lysis on sheep blood agar plates. The hemolytic activity was not detected in the culture supernatant nor was any DNA sequence homologous to the E. coli -hemolysin gene detected in the chromosome or plasmid DNA of the strain, indicating that the observed hemolysis was different from -type. To identify the genetic determinant responsible for the hemolysis, we performed random Tn5 insertional mutagenesis and obtained one mutant, named M5005, that totally lacked the hemolytic activity. Cloning and nucleotide sequencing of the region flanking the transposon insertion site in the M5005 chromosome revealed that the transposon was inserted within an open reading frame of the cyclic AMP receptor protein (CRP) gene, which is involved in one of the global regulatory networks of gene expression in E. coli. Nucleotide sequence analysis of the intact crp gene of the strain M1000 showed that the CRP protein of M1000 is 99% identical to that of K-12. Introduction of the intact crp gene on a low copy plasmid into the mutant M5005 restored the hemolytic phenotype, confirming that the mutation site in M5005 was in the crp gene. CRP plays a central role in catabolite repression, the phenomenon by which the synthesis of many enzymes required to metabolize various sugars is repressed in the presence of glucose. When the hemolytic activity of E. coli M1000 grown in the presence of glucose was examined, the hemolysis was totally impaired. These results indicate that the avian pathogenic E. coli strain M1000 produces a hemolysin the expression of which is dependent on crp gene function. 相似文献
856.
Development of immune assay system for both CpG and non-CpG DNA from lactic acid bacteria using a transfectant of swine Toll-like receptor 9 总被引:2,自引:1,他引:2
Takeshi SHIMOSATO Haruki KITAZAWA Masanori TOHNO Shinichiro KATOH Yasushi KAWAI Tadao SAITO 《Animal Science Journal》2004,75(4):377-382
Bacterial DNA is expected to be a potent immune stimulating agent to Toll‐like receptor (TLR) 9 expressed cells such as macrophages, monocytes, B lymphocytes, NK cells and dendritic cells. In the present study, we constructed a transfectant of swine TLR9 with mammalian cells. We demonstrated that the transfectant, recognizing both CpG and non‐CpG oligonucleotides from lactic acid bacteria, induced NF‐κB activation by gene reporter assay. These findings indicate that the swine TLR9 transfectant will be highly useful for the screening of immunostimulatory DNA from lactic acid bacteria. 相似文献
857.
Michinari YOKOHAMA Takeshi MASUDA Takashi AMANO Hiroki HIRAYAMA Takashi MANABE 《Animal Science Journal》2004,75(5):401-405
As an analysis of the cashmere proteins by Type IV 2‐DE, ten kinds of components, including three components with molecular mass 42–50 kDa whose expression level increased in the winter, were separated. In analyzing nine components of these ten using a mass spectrometer, the three components of molecular mass 70–120 kDa and pI 5.3 were identified as keratin type II microfibrillar (accession no. KRSHL2 ), keratin 48 k type I microfibrillar component 8c‐1 (accession no. KRSHL1 ) and cytosolic phospholipase A2 (accession no. O77793 ), respectively. The three components whose expression level increased in the winter, were identified as keratin type I microfibrillar 48 kDa component 8C‐1 (accession no. P02534 ) and keratin type I microfibrillar 47.6 kDa (accession no. P25690 ) (pI 5.2/42 kDa), keratin type II microfibrillar component 7C (accession no. P15241 ) and keratin typeII‐sheep (accession no. S34165 ) (pI 5.5/45 kDa), and the keratin type II microfibrillar component 5 (accession no. P25691 ) (pI 5.8–6.0/45 kDa), respectively. The three components of less than 17 kDa were identified as hair keratin type II intermediate filament (accession no. CAA51836 ) (pI 5.2) and keratin high‐sulfur matrix protein IIIB2 (accession no. P02447 ) with a different isoelectric point (pI 5.4 and 5.9), respectively. 相似文献
858.
859.
860.
Takashi Kadono Nozomu Kira Kengo Suzuki Osamu Iwata Takeshi Ohama Shigeru Okada Tomohiro Nishimura Mai Akakabe Masashi Tsuda Masao Adachi 《Marine drugs》2015,13(8):5334-5357
Carotenoids exert beneficial effects on human health through their excellent antioxidant activity. To increase carotenoid productivity in the marine Pennales Phaeodactylum
tricornutum, we genetically engineered the phytoene synthase gene (psy) to improve expression because RNA-sequencing analysis has suggested that the expression level of psy is lower than other enzyme-encoding genes that are involved in the carotenoid biosynthetic pathway. We isolated psy from P. tricornutum, and this gene was fused with the enhanced green fluorescent protein gene to detect psy expression. After transformation using the microparticle bombardment technique, we obtained several P. tricornutum transformants and confirmed psy expression in their plastids. We investigated the amounts of PSY mRNA and carotenoids, such as fucoxanthin and β-carotene, at different growth phases. The introduction of psy increased the fucoxanthin content of a transformants by approximately 1.45-fold relative to the levels in the wild-type diatom. However, some transformants failed to show a significant increase in the carotenoid content relative to that of the wild-type diatom. We also found that the amount of PSY mRNA at log phase might contribute to the increase in carotenoids in the transformants at stationary phase. 相似文献