全文获取类型
收费全文 | 788篇 |
免费 | 40篇 |
专业分类
林业 | 96篇 |
农学 | 23篇 |
基础科学 | 3篇 |
226篇 | |
综合类 | 40篇 |
农作物 | 67篇 |
水产渔业 | 45篇 |
畜牧兽医 | 257篇 |
园艺 | 15篇 |
植物保护 | 56篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 10篇 |
2021年 | 23篇 |
2020年 | 25篇 |
2019年 | 37篇 |
2018年 | 29篇 |
2017年 | 25篇 |
2016年 | 28篇 |
2015年 | 23篇 |
2014年 | 32篇 |
2013年 | 47篇 |
2012年 | 61篇 |
2011年 | 70篇 |
2010年 | 54篇 |
2009年 | 30篇 |
2008年 | 47篇 |
2007年 | 57篇 |
2006年 | 33篇 |
2005年 | 36篇 |
2004年 | 37篇 |
2003年 | 30篇 |
2002年 | 25篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1974年 | 1篇 |
1972年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有828条查询结果,搜索用时 31 毫秒
11.
Cecilia Mónica Galosi Viviana Cid de la Paz Leandro Carlos Fernández Javier Pablo Martinez María Isabel Craig María Barrandeguy María Elisa Etcheverrrigaray 《Journal of veterinary diagnostic investigation》2005,17(5):500-502
This study describes the isolation of equine herpesvirus-2 (EHV-2) from the lung of an aborted equine fetus in Argentina. The isolated virus was confirmed as EHV-2 by indirect immunofluorescence using a rabbit anti-EHV-2 polyclonal antiserum and by virus-neutralization test using an equine polyclonal antibody against EHV-2. Restriction endonuclease DNA fingerprinting with BamHI also confirmed the identity of the virus as EHV-2. Furthermore, viral nucleic acid was detected by polymerase chain reaction from the original lung sample and from the DNA obtained from cells infected with the virus isolate. This work constitutes the first reported isolation of EHV-2 from an aborted equine fetus. The presence of EHV-2 in the lung of the aborted fetus would indicate that this virus is capable of crossing the placental barrier. However, no cause-effect relationship was established between the EHV-2 isolate and the abortion. 相似文献
12.
PE Bennemann GN Diehl E Milbradt RM Vidor HCC Fries I Wentz ML Bernardi FP Bortolozzo 《Reproduction in domestic animals》2005,40(6):507-510
This study evaluated the reproductive performance of gilts inseminated at three intervals before ovulation (0-12, 13-23, 24-30 h) with sperm doses (SD) stored for 0-48 and 96-120 h. A total of 218 PIC Camborough 22 gilts were inseminated once with SD of 1.5 x 10(9) sperms. Pregnant gilts (n = 166) were slaughtered 30.8 +/- 3.7 days after artificial insemination. The number of corpora lutea (CL) and total embryos (TE) was counted. Pregnancy rates (PR) were analysed by chi-square test. TE and embryonic survival (ES), obtained as the ratio between viable embryos and CL, were analysed by GLM procedure (SAS) and mean values were compared by Tukey's test. Pregnancy rate was similar among artificial insemination-ovulation (AIOV) intervals when semen was stored for 0-48 h. However, the lowest PR was observed in the 24-30 h AIOV interval with storage time (ST) of 96-120 h (p < 0.05). There was a significant effect of the interaction between ST and AIOV (p < 0.05) on TE and ES variables. Total embryos and ES did not differ (p > 0.05) among AIOV intervals in ST of 0-48 h. However, gilts inseminated at 24-30 h AIOV interval with ST of 96-120 h showed a reduction of 6.7 embryos (p < 0.05) compared with gilts in the same interval inseminated with semen stored for 0-48 h. ES for the 24-30 h AIOV interval and ST of 96-120 h was lower than that observed in the other groups (p < 0.05). 相似文献
13.
Follicular Dynamics in Heifers during Pre-pubertal and Pubertal Period Kept under Two Levels of Dietary Energy Intake 总被引:1,自引:0,他引:1
MA Romano VH Barnabe JP Kastelic CA de Oliveira RM Romano 《Reproduction in domestic animals》2007,42(6):616-622
The objective of this study was to characterize follicular dynamics in pre-pubertal, pubertal and post-pubertal periods, as well as the effect of high-energy intake on follicular development and age at puberty in heifers. Thirty-one Nelore (Bos indicus) heifers, 6 months old, were randomly assigned to receive two different diets: one of low (GI) and other of high dietary energy intake (GII). Animals were evaluated in relation to body weight gain by being weighed every 21 days. Heifers were evaluated every other day by real-time linear ultrasonography to characterize ovarian structures development from weaning to post-pubertal period. Blood samples were collected to determine plasmatic concentrations of progesterone by RIA method. The ovulation was determined when progesterone concentrations were >1 ng/mL in three consecutive samples, and by ultrasound images of corpus luteum; and oestrous behaviour in some animals. Age at puberty differed among heifers of GII (17.00 +/- 0.46 months) compared with heifers of GI (19.87 +/- 0.47 months; p < or = 0.05). Maximum size of the dominant follicles at pre-pubertal period was greater in GII heifers than in GI (10.52 +/- 0.33 and 9.76 +/- 0.15 mm, respectively; p < or = 0.05). As heifers approached first ovulation time, size of dominant follicle increased (11.75 +/- 0.37 mm for GI and 12.52 +/- 0.91 mm for GII; p < or = 0.05). Body weight at puberty was not different in both groups (302.33 +/- 27.31 kg for GI and 326.19 +/- 27.78 kg for GII heifers; p > 0.05). We conclude that animals receiving high dietary energy intake attained the puberty earlier and the development of follicles were different than in low dietary energy intake. 相似文献
14.
Eduardo Segundo Dietrich E. Lesemann Germán Martín María P. Carmona Leticia Ruiz Isabel M. Cuadrado Leonardo Velasco Dirk Janssen 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(1):81-87
Amaranthus leaf mottle virus (AmLMV) was classified as a member of the genus Potyvirus on the basis of its particle morphology, serology, and biological properties (Casetta et al., 1986). Based on these properties, an Amaranthus viridis-infecting virus isolated in Spain, causing mottle and leaf blistering as well as reduced growth has been identified as AmLMV.
The 3′ terminal genomic region of this and a reference isolate from Italy has been sequenced and reveals a 95% nucleotide
identity between the two isolates. The sequenced part comprises the coat protein with 281 amino acids and 315 nucleotides
of the 3′ untranslated region (UTR) preceding a polyadenylated tail. Pairwise comparisons and phylogenetic analysis of the
nucleotide and deduced amino acid sequences of the CP and 3′ UTR of the cloned cDNAs with those of other potyviruses shows
that AmLMV is a distinct potyvirus closely related to Potato virus Y. 相似文献
15.
Helena P. Trenado Isabel M. Fortes Diamantina Louro Jesús Navas-Castillo 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(2):193-196
Tomato chlorosis virus causes yellow leaf disorder epidemics in many countries worldwide. Plants of Physalis ixocarpa showing abnormal interveinal yellowing and plants of Physalis peruviana showing mild yellowing collected in the vicinity of tomato crops in Portugal were found naturally infected with ToCV. Physalis ixocarpa and P. peruviana were tested for susceptibility to ToCV by inoculation with Bemisia tabaci, Q biotype. Results confirmed that ToCV is readily transmissible to both species. The infection was expressed in P. ixocarpa by conspicuous interveinal yellow areas on leaves that developed into red or brown necrotic flecks, while P. peruviana test plants remained asymptomatic. Infected plants of both P. ixocarpa and P. peruviana served as ToCV sources for tomato infection via B. tabaci transmission. This is the first report of P. ixocarpa and P. peruviana as natural hosts of ToCV. 相似文献
16.
Three new homoisoflavanones, namely ledebourin A (1), ledebourin B (2) and ledebourin C (3) were isolated from the bulbs of Ledebouria floribunda. Their structures were elucidated on the basis of detail spectroscopic analyses. This is the first report of this type of homoisoflavanones. Ledebourin B (2) and ledebourin C (3) exhibited potent antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging compared to the positive controls, the well-known antioxidant BHT and BHA. 相似文献
17.
Isabel Guadano Procesi Azzurra Carnio Federica Berrilli Margherita Montalbano Di Filippo Alessia Scarito Cristina Amoruso Marco Barni Marco Ruffini Giulia Barlozzari Manuela Scarpulla Claudio De Liberato 《Zoonoses and public health》2022,69(1):46-54
Giardia duodenalis is the most common intestinal protozoan in humans and animals worldwide, including eight morphologically identical assemblages, infecting pets, livestock, wildlife and human beings. Assemblages A and B are those with the higher zoonotic potential, and they have been detected in several mammals other than humans; the others (C to H) show a higher host specificity. Cats can harbour both the specific Assemblage F and the zoonotic ones A and B. Several studies have been carried out on G. duodenalis genotypes in cats; however, the role of this species in the epidemiology of giardiasis is still poorly understood. In this scenario, the present study carried out the detection and genetic characterization at sub-assemblage level of G. duodenalis from colony stray cats in central Italy. In the period 2018–2019, 133 cat faecal samples were analysed for the presence of G. duodenalis cysts by a direct immunofluorescence assay. Positive samples were subsequently subjected to molecular analyses for assemblage/sub-assemblage identification. Forty-seven samples (35.3%) were positive for G. duodenalis cysts by immunofluorescence. G. duodenalis DNA was amplified at SSU-rDNA locus from 39 isolates: 37 were positive for zoonotic Assemblage A and 2 showed a mixed infection (A + B). Positive results for the β-giardin gene were achieved for 25 isolates. Sequence analysis revealed 16 isolates belonging to Sub-assemblage AII and 8 to Sub-assemblage AIII. One isolate resulted as ambiguous AI/AIII. Large sequence variability at the sub-assemblage level was detected, with several double peaks and mutations, making complex a proper isolate allocation. When compared with previous studies, the 35.3% prevalence of G. duodenalis in cats reported in the present article was surprisingly high. Moreover, all positive cats resulted to be infected with zoonotic assemblages/sub-assemblages, thus indicating stray cats as a possible source of human giardiasis and highlighting the sanitary relevance of cat colonies in the study area. 相似文献
18.
Differential expression of genes encoding cell wall proteins in vascular tissues from vertical and bent loblolly pine trees 总被引:1,自引:0,他引:1
Differential expression of cell wall proteins during plant development and in response to biotic or abiotic stress suggests that these proteins may contribute in different ways to plant cell wall architecture. Because the wood of loblolly pine (Pinus taeda L.) is highly specialized in the formation of secondary cell walls, it is an ideal tissue for studying these proteins. The cDNAs coding for six novel cell wall associated proteins, as well as a homologue for a phytocyanin, were identified and characterized from differentiating xylem of loblolly pine. Three of these cDNAs encoded new putative loblolly pine arabinogalactan proteins, based on their structural similarity to classical arabinogalactan proteins (AGPs). In addition, one clone was related to the proline-rich protein group and the other two to the glycine-rich protein group and the mussel adhesive protein. Relative expression of these genes was examined in different tissues and organs from normal trees (needles, phloem and vertical wood), the underside of bent trees (compression wood) and the lateral sides of the bent stems (side wood). All clones, except one, were highly expressed in vascular tissues with noticeable differences among the three types of wood. Their relationships and diversity provide the first insights into concerted expression and related function for this important group of proteins in cell wall formation of wood. 相似文献
19.
Jorge Miguel Silva Faria Inês Sena Bruno Ribeiro Ana Margarida Rodrigues Carla Maria Nobre Maleita Isabel Abrantes Richard Bennett Manuel Mota Ana Cristina da Silva Figueiredo 《Journal of pest science》2016,89(1):207-217
The Columbia root-knot nematode (CRKN), Meloidogyne chitwoodi, is an EPPO A2 type quarantine pest since 1998. This nematode causes severe damage in economically important crops such as potato and tomato, making agricultural products unacceptable for the fresh market and food processing. Commonly used nematicidal synthetic chemicals are often environmentally unsafe. Essential oils (EOs) may constitute safer alternatives against RKN. EOs, isolated from 56 plant samples, were tested against CRKN hatching, in direct contact bioassays. Some of the most successful EOs were fractionated and the hydrocarbon molecules (HM) and oxygen-containing molecules (OCM) fractions tested separately. 24 EOs displayed very strong hatching inhibitions (≥90 %) at 2 µL mL?1 and were further tested at lower concentrations. Dysphaniaambrosioides, Filipendula ulmaria, Ruta graveolens, Satureja montana and Thymbra capitata EOs revealed the lowest EC50 values (<0.15 µL mL?1). The main compounds of these EOs, namely 2-undecanone, ascaridol, carvacrol, isoascaridol, methyl salicylate, p-cymene and/or γ-terpinene, were putatively considered responsible for CRKN hatching inhibition. S. montana and T. capitata OCM fractions showed hatching inhibitions higher than HM fractions. The comparison of EO and corresponding fractions EC50 values suggests interactions between OCM and HM fractions against CRKN hatching. These species EOs showed to be potential environmentally friendly CRKN hatching inhibitors; nonetheless, bioactivity should be considered globally, since its HM and OCM fractions may contribute, diversely, to the full anti-hatching activity. 相似文献
20.