全文获取类型
收费全文 | 1064篇 |
免费 | 70篇 |
国内免费 | 1篇 |
专业分类
林业 | 47篇 |
农学 | 39篇 |
基础科学 | 1篇 |
111篇 | |
综合类 | 129篇 |
农作物 | 17篇 |
水产渔业 | 74篇 |
畜牧兽医 | 633篇 |
园艺 | 37篇 |
植物保护 | 47篇 |
出版年
2023年 | 21篇 |
2022年 | 14篇 |
2021年 | 31篇 |
2020年 | 35篇 |
2019年 | 38篇 |
2018年 | 31篇 |
2017年 | 33篇 |
2016年 | 29篇 |
2015年 | 36篇 |
2014年 | 35篇 |
2013年 | 33篇 |
2012年 | 96篇 |
2011年 | 81篇 |
2010年 | 50篇 |
2009年 | 32篇 |
2008年 | 76篇 |
2007年 | 55篇 |
2006年 | 50篇 |
2005年 | 49篇 |
2004年 | 45篇 |
2003年 | 43篇 |
2002年 | 30篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 3篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1972年 | 9篇 |
1971年 | 6篇 |
1970年 | 6篇 |
1927年 | 2篇 |
排序方式: 共有1135条查询结果,搜索用时 296 毫秒
971.
972.
David B. Lindenmayer Jeff T. Wood Ross B. Cunningham Mason Crane Christopher Macgregor Damian Michael Rebecca Montague-Drake 《Landscape Ecology》2009,24(8):1091-1103
We implemented a replicated before-after-control-impact (BACI) experiment to quantify vertebrate response in native forest
patches to a major change in the surrounding exotic Radiata Pine (Pinus radiata) plantation. We contrasted vertebrate occupancy of patches of native eucalypt forest where the surrounding stands of exotic
Radiata Pine (Pinus radiata) were clearfelled (termed “treatment patches”) with matched “control patches” where surrounding pine stands remained unlogged.
Different species of arboreal marsupials varied in their response to our experimental treatments. The Common Ringtail Possum
was unaffected by cutting of the surrounding pine stands, whereas all sightings of the Mountain Brushtail Possum were in control
patches. For birds, species richness was significantly reduced by 4–9 species in treatment patches. Birds with cup and dome
nests were those negatively affected by the cutting of the surrounding pine stands. They may be susceptible to altered microclimatic
conditions or increasing levels of nest predation when the surrounding pine matrix is clearfelled. Our study emphasized how
the biota inhabiting retained patches of native forest within plantation landscapes can be changed when stands of surrounding
Radiata Pine are clearfelled. In the case of birds, more species will be maintained within eucalypt patches if logging is
scheduled so that not all the surrounding pine plantation is clearfelled at once. 相似文献
973.
Bellamy Chloe Boughey Katherine Hawkins Charlotte Reveley Sonia Spake Rebecca Williams Carol Altringham John 《Landscape Ecology》2020,35(4):1001-1020
Landscape Ecology - Habitat suitability models (HSM) can improve our understanding of a species’ ecology and are valuable tools for informing landscape-scale decisions. We can increase HSM... 相似文献
974.
Benjamin T. Jakobek Rebecca C. McOnie Susan L. Fubini Galina Hayes 《The Canadian veterinary journal. La revue veterinaire canadienne》2021,62(12):1292
A 7-month-old Hampshire ram, with no history of trauma or breeding, was referred for treatment of acute, unilateral scrotal swelling. Physical examination revealed a moderately sized, soft, left-sided, non-reducible swelling of the proximal scrotum and mild swelling of the scrotal neck. Ultrasound evaluation of the scrotum revealed morphologically normal testicles and a mild accumulation of free fluid in the left vaginal tunic. Unilateral, laparoscopic inguinal herniorrhaphy under general anesthesia was performed. The herniated omentum was reduced and barbed suture was used to imbricate the internal inguinal ring and the vaginal ring. No recurrence of herniation was reported 5 months after surgery.Key clinical message:Laparoscopic inguinal herniorrhaphy with barbed suture can be a safe and effective means of scrotal hernia resolution in a ram. When performed by a competent surgeon experienced in laparoscopy, this treatment for inguinal and scrotal herniation may minimize post-operative pain, provide a rapid return to function, and preserve normal testicular and scrotal anatomy. 相似文献
975.
Walton MC Lentle RG Reynolds GW Kruger MC McGhie TK 《Journal of agricultural and food chemistry》2006,54(20):7940-7946
The effect of a simultaneous intake of food or flavonoids on anthocyanins absorption and antioxidant status in pigs was investigated. Twelve male pigs at 27.1 +/- 0.7 kg BW fitted with jugular venous cannulae were maintained in individual metabolic crates. The animals were each given one of three dietary treatments in random order: blackcurrant powder (BC) to give a dose of 100 mg total ACNs/kg BW mixed either with water and sugar (Diet A), cereal (Weet-Bix), milk, and sugar (Diet B), or cereal, milk, sugar, and an additional flavonol (rutin, approximately 100 mg/kg BW) (Diet C). The four major anthocyanins of BC, delphinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-glucoside, and cyanidin-3-rutinoside, were identified and quantified by HPLC-PDA in all three diets. In the pig plasma, four peaks with a reversed pattern to those of anthocyanins in the BC extract were detected. The total amount of anthocyanins absorbed was not significantly different between the three diets, but the rate of absorption and subsequent decline was slower following administration of diet B and C than diet A. All three diets increased antioxidant capacity when measured by the FRAP assay but not when measured by the ORAC and non-protein ORAC assay. However, the increase was delayed and did not appear until 4 h after ingestion, at a time when plasma anthocyanin levels had returned to baseline. The present study demonstrates that the simultaneous intake of food or other flavonoids delays the absorption profile for anthocyanins. Our results also suggest that the increase in antioxidant capacity is not due to dietary anthocyanins but may be due to metabolites that result from anthocyanin consumption. 相似文献
976.
Small-scale Forestry - This study employs in-depth qualitative and quantitative research methods including survey and other ethnographic methods, concept mapping and informal qualitative... 相似文献
977.
Rebecca Veronesi Marina Morach Ella Hübschke Claudia Bachofen Roger Stephan Magdalena Nüesch‐Inderbinen 《Zoonoses and public health》2021,68(1):8-11
Hepatitis E virus (HEV) is the causative agent of an acute and in most cases self‐limiting hepatitis. Of the four major HEV genotypes that infect humans, genotype 3 and 4 are zoonotic and have been identified in humans but predominantly in pigs and wild boar, which are considered the main reservoirs. However, the known host range of zoonotic HEV may be increasing to comprise additional species, including companion animals. Several studies have identified contact with dogs as a risk factor for HEV infection in humans, yet information on the occurrence of HEV in Swiss dogs is lacking. To examine a possible risk of exposure, this study was designed to assess the seroprevalence of HEV in 84 Swiss dogs. Serum and plasma samples collected from four veterinary clinics were screened for HEV‐specific antibodies by HEV‐antibody ELISA test kit. In addition, information of 22 dogs regarding the country of origin, the type of dog feed and any history of hunting was recorded. Samples from seropositive animals were also screened for the presence of HEV RNA by quantitative real‐time RT‐PCR (qRT‐PCR). Overall, 38% (32 of 84) of the dogs tested seropositive for anti‐HEV, indicating exposure to HEV. Among the 22 dogs for which information was available, HEV‐specific antibodies were detected in three of five dogs that were born abroad, in one of two dogs that were fed a raw meat‐based diet, and in one hunting dog. No viral RNA could be detected in any of the serum and plasma samples; thus, the genotype of the strains remained undetermined. This study provides further evidence for canine exposure and susceptibility to HEV and highlights the need to further assess the risks of HEV transmission to humans with contact to dogs. 相似文献
978.
Rebecca L. Stepien DVM MS Keith G. Benson DVM Lisa J. Forrest VMD 《Veterinary radiology & ultrasound》1999,40(6):606-610
Right lateral, left lateral and ventrodorsal radiographs were obtained in 20 normal ferrets (11 male). Three independent observers recorded measurements of the cardiac silhouette and results for each parameter were averaged. Long axis (length), short axis (width) and total of length plus width (L+W) were recorded in each view. Comparative measurements were calculated, including the ratio of L+W/length of thoracic vertebrae 5-8, and a modified vertebral heart score (VHS) method, measuring the heart in vertebral units. Measurements made in ventrodorsal views were usually larger than corresponding measurements in lateral views. Weight and most absolute measurements differed significantly between male and female ferret (P<0.05), but the differences in absolute measurements were not apparent when related to measures of body size (Ratio and modified VHS methods). Given the variability in body weight and size in ferrets, measurements of the cardiac silhouette normalized for body size may be more universally applicable than absolute measurements. 相似文献
979.
Maria R. Finckh Rebecca J. Nelson 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(8):743-751
Eight Philippine races of Xanthomonas oryzae pv. oryzae have been identified based on virulence phenotypes observed on a set of five differential varieties. One of these, Race 3, was found to consist of two phylogenetically distinct lineages based on DNA fingerprinting analysis. To determine, if the two lineages could be differentiated based on host-specificity, 186 strains of Race 3 were analyzed with additional fingerprints and 76 selected isolates with additional differential rice varieties. The strains were separated into 36 haplotypes clustering in three groups (IS1113-B, -C, and -G) at the 75% similarity level. Isolates varied in their reaction to a rice line carrying the resistance gene Xa7, however, the variability was not consistent within lineage. Aggressiveness of isolates belonging to lineage IS1113-B and -G was significantly greater when tested during the dry season than when tested during the wet season. However, no such differences were evident for isolates from lineage IS1113-C, indicating that environmental effects presumably light and temperature are genotype-specific. 相似文献
980.
ZONG Xu-xiao Rebecca Ford Robert R Redden GUAN Jian-ping WANG Shu-min 《中国农业科学(英文版)》2009,8(3):257-267
To assesse the genetic diversity among wild and cultivated accessions of 8 taxonomic groups in 2 species, and 5 subspecies under Pisum genus, and to analyze population structure and their genetic relationships among various groups of taxonomy, the study tried to verify the fitness of traditionally botanical taxonomic system under Pisum genus and to provide essential information for the exploration and utilization of wild relatives of pea genetic resources. 197 Pisum accessions from 62 counties of 5 continents were employed for SSR analysis using 21 polymorphic primer pairs in this study. Except for cultivated field pea Pisum sativum ssp. sativum var. sativum (94 genotypes), also included were wild relative genotypes that were classified as belonging to P. fulvum, P. sativum ssp.abyssinicum, P. sativum ssp. asiaticum, P. sativum ssp. transcaucasicum, P. sativum ssp. elatius var. elatius, P. sativum ssp. elatius var. pumilio and P. sativum ssp. sativum var. arvense (103 genotypes). The PCA analyses and 3-dimension PCA graphs were conducted and drawn by NTSYSpc 2.2d statistical package. Nei78 genetic distances among groups of genetic resources were calculated, and cluster analysis using UPGMA method was carried out by using Popgene V1.32 statistical package, the dendrogram was drawn by MEGA3.1 statistical package. Allelic statistics were carried out by Popgene V1.32. The significance test between groups of genotypes was carried out by Fstat V2.9.3.2 statistical package. 104 polymorphic bands were amplified using 21 SSR primer pairs with unambiguous unique polymorphic bands. 4.95 alleles were detected by each SSR primer pair in average, of which 65.56% were effective alleles for diversity. PSAD270, PSAC58, PSAA18, PSAC75, PSAA175 and PSAB72 were the most effective SSR pairs. SSR alleles were uniformly distributed among botanical taxon units under Pisum genus, but significant difference appeared in most pairwise comparisons for genetic diversity between taxon unit based groups of genetic resources. Genetic diversity level of wild species P. fulvum was much lower than the cultivated species P. sativum. Under species P. sativum, P. sativum ssp. sativum var. sativum and P. sativum ssp. asiaticum were the highest in gentic diversity, followed by P. sativum ssp. elatius var. elatius and P. sativum ssp. transcaucasicum, P. sativum ssp. elatius var. pumilio, P. sativum ssp. sativum vat. arvense and P. sativum ssp. abyssinicum were the lowest. Four gene pool clusters were detected under Pisum genus by using PCA analysis. Gene pool "fulvum" mainly consisted of wild species Pisum fulvum, gene pool "abyssinicum" mainly consisted of P. sativum ssp. abyssinicum, and gene pool "arvense" mainly consisted of P. sativum ssp. sativum var. arvense. While gene pool "sativum" were composed by 5 botanical taxon units, they are P. sativum ssp. asiaticum, P. sativum ssp. elatius var. elatius, P. sativum ssp. transcaucasicum, P. sativum ssp. elatius var. pumilio and P. sativum ssp. sativum var. sativum. "sativum" gene pool constructed the primary gene pool of cultivated genetic resources; "fulvum" gene pool, "abyssinicum" gene pool and "arvense" gene pool together constructed the secondary gene pool of cultivated genetic resources. Pairwise Nei78 genetic distance among botanical taxon based groups of pea genetic resources ranged from 7.531 to 35.956, 3 large cluster groups were identified based on the UPGMA dendrogram. Group Ⅰ equals to "sativum" and "arvense" gene pools, Group Ⅱ equals to "abyssinicum" gene pool, and Group Ⅲ equals to "fulvum" gene pool. The UPGMA clustering results generally supporting the PCA clusting results. There were significant differences among most botanical groups under Pisum genus, with clear separation of four gene pools for genetic diversity structure. The research results partially support the traditional botanical taxonomy under Pisum genus, and pointed out its advantage and shortcoming. In order to broaden the genetic bases of pea varieties, the genetic potentials in the four gene pools should be thoroughly exploited. 相似文献