全文获取类型
收费全文 | 341篇 |
免费 | 32篇 |
国内免费 | 2篇 |
专业分类
林业 | 19篇 |
农学 | 24篇 |
基础科学 | 1篇 |
24篇 | |
综合类 | 53篇 |
农作物 | 8篇 |
水产渔业 | 16篇 |
畜牧兽医 | 219篇 |
园艺 | 5篇 |
植物保护 | 6篇 |
出版年
2023年 | 5篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 19篇 |
2013年 | 24篇 |
2012年 | 10篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 20篇 |
2008年 | 13篇 |
2007年 | 18篇 |
2006年 | 11篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 18篇 |
1997年 | 16篇 |
1996年 | 16篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1967年 | 1篇 |
1963年 | 1篇 |
1955年 | 1篇 |
1941年 | 1篇 |
1940年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有375条查询结果,搜索用时 31 毫秒
81.
JM Castillo JC Dockweiler SH Cheong M Diel de Amorim 《Reproduction in domestic animals》2018,53(1):274-277
A 13‐year‐old Romanov sheep presented for evaluation of vaginal discharge, depression and anorexia. Blood work demonstrated mature neutrophilia and marked hyperlactatemia. Transrectal and transabdominal ultrasound revealed echogenic fluid (pus) within the uterus. Purulent uterine fluid culture yield Escherichia coli. A diagnosis of pyometra was made. After medical treatment without clinical improvement, an exploratory laparotomy was performed, and a 360‐degree uterine left horn torsion was identified with the pyometra and multiple corpora lutea on both ovaries. Ovariohysterectomy was performed and the ewe recovered uneventfully. 相似文献
82.
B Dilday DA Howell SB Cenko JM Silverman PE Nugent M Sullivan S Ben-Ami L Bildsten M Bolte M Endl AV Filippenko O Gnat A Horesh E Hsiao MM Kasliwal D Kirkman K Maguire GW Marcy K Moore Y Pan JT Parrent P Podsiadlowski RM Quimby A Sternberg N Suzuki DR Tytler D Xu JS Bloom A Gal-Yam IM Hook SR Kulkarni NM Law EO Ofek D Polishook D Poznanski 《Science (New York, N.Y.)》2012,337(6097):942-945
There is a consensus that type Ia supernovae (SNe Ia) arise from the thermonuclear explosion of white dwarf stars that accrete matter from a binary companion. However, direct observation of SN Ia progenitors is lacking, and the precise nature of the binary companion remains uncertain. A temporal series of high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex circumstellar environment that provides an unprecedentedly detailed view of the progenitor system. Multiple shells of circumstellar material are detected, and the SN ejecta are seen to interact with circumstellar material starting 59 days after the explosion. These features are best described by a symbiotic nova progenitor, similar to RS Ophiuchi. 相似文献
83.
I Ruiz‐González MA Sánchez RA García‐Fernández P García‐Palencia B Sánchez CA Letelier A González‐Bulnes JM Flores 《Reproduction in domestic animals》2012,47(2):274-280
The objective of this study was to investigate differences on the endometrial immunoexpression of type I IFN receptor subunit 1 (IFNAR1) and oxytocin receptor (OTR) during the time of maternal recognition of pregnancy in sheep, when oestrus is synchronized with either prostaglandin analogues (group PG) or conventional progestagens (group P). Plasma progesterone was measured from day 0 to 21 post‐coitus (pc) (day 0 = day of oestrus). Immunohistochemistry was performed in samples of uterine horns from pregnant sheep on days 9pc, 13pc, 15pc, 17pc and 21pc to locate IFNAR1 and OTR expression in different endometrial compartments. Mean levels of plasma progesterone were different between treatments, obtaining higher levels in the PG group than in the P group (p < 0.05). Comparing days of pregnancy, IFNAR1 protein expression was different in the luminal epithelium (LE) (p < 0.05), while OTR was different in the LE and in the superficial glandular epithelium (SG) (p < 0.05). Temporal variation on the expression of both proteins from day 9pc to 21pc has been evidenced. IFNAR1 and OTR expression did not show significant differences between treatments. However, the response observed in the endometrium was highly inconsistent when prostaglandin analogues were used. Therefore, the protocol based on prostaglandin analogues still needs to be optimized before being considered as a better alternative to progestagens for oestrous synchronization in sheep. 相似文献
84.
I Parrilla D del Olmo I Caballero T Tarantini C Cuello MA Gil J Roca EA Martinez JM Vazquez 《Reproduction in domestic animals》2012,47(6):965-974
The objective of this study was to optimize protocols for the cryopreservation of sex‐sorted boar spermatozoa. In the experiment 1, we evaluated the effects of a standard boar sperm cryopreservation procedure (3% final glycerol concentration) on the in vitro characteristics of sex‐sorted sperm frozen at low sperm concentrations (20 × 106 sperm/ml; S20 group). Non‐sorted spermatozoa frozen at 1000 × 106 (C1000 group) and 20 × 106 (C20 group) sperm/ml were used as the freezing control groups. In experiment 2, the effects of different final glycerol concentrations (0.16%, 0.5%, 1.0%, 2.0% and 3.0%) on post‐thaw quality of the S20 and C20 groups were evaluated. In both experiments, the samples were evaluated prior to freezing (5°C) and at 30, 90 and 150 min after thawing. Experiment 1 indicated that freezing sperm at low concentrations decreased (p < 0.05) the total motility (TM) and progressive motility (PM) at 90 and 150 min after thawing regardless of whether the sperm were sorted or not. However, the sperm membrane integrity was not affected at any evaluation step. Inexperiment 2, significant effects on the TM and PM because of increased glycerol concentrations in the S20 and C20 groups were observed only at 90 and 150 min after thawing. The samples frozen in 3% glycerol showed lower (p < 0.05) TM and PM values when compared to those frozen in the presence of 0.5% and 1% glycerol. In both experiments, non‐sorted control samples displayed higher percentages of spermatozoa with damaged DNA than sorted spermatozoa. In conclusion, the optimization of cryopreservation conditions by decreasing the glycerol concentrations can improve post‐thaw motility of sex‐sorted spermatozoa frozen at low concentrations. 相似文献
85.
High-frequency soil CO(2) flux data are valuable for providing new insights into the processes of soil CO(2) production. A record of hourly soil CO(2) fluxes from a semi-arid ponderosa pine stand was spatially and temporally deconstructed in attempts to determine if variation could be explained by logical drivers using (i) CO(2) production depths, (ii) relationships and lags between fluxes and soil temperatures, or (iii) the role of canopy assimilation in soil CO(2) flux variation. Relationships between temperature and soil fluxes were difficult to establish at the hourly scale because diel cycles of soil fluxes varied seasonally, with the peak of flux rates occurring later in the day as soil water content decreased. Using a simple heat transport/gas diffusion model to estimate the time and depth of CO(2) flux production, we determined that the variation in diel soil CO(2) flux patterns could not be explained by changes in diffusion rates or production from deeper soil profiles. We tested for the effect of gross ecosystem productivity (GEP) by minimizing soil flux covariance with temperature and moisture using only data from discrete bins of environmental conditions (±1 °C soil temperature at multiple depths, precipitation-free periods and stable soil moisture). Gross ecosystem productivity was identified as a possible driver of variability at the hourly scale during the growing season, with multiple lags between ~5, 15 and 23 days. Additionally, the chamber-specific lags between GEP and soil CO(2) fluxes appeared to relate to combined path length for carbon flow (top of tree to chamber center). In this sparse and heterogeneous forested system, the potential link between CO(2) assimilation and soil CO(2) flux may be quite variable both temporally and spatially. For model applications, it is important to note that soil CO(2) fluxes are influenced by many biophysical factors, which may confound or obscure relationships with logical environmental drivers and act at multiple temporal and spatial scales; therefore, caution is needed when attributing soil CO(2) fluxes to covariates like temperature, moisture and GEP. 相似文献
86.
This study was conducted to measure the concentration of cefquinome in the endometrium of mares after intrauterine treatment and to evaluate associated inflammation. Mares (n = 14) were randomly assigned to one of the following groups: (i) control (n = 4) were either not treated (n = 2) or received (n = 2) lactated Ringer's intrauterine for 1 or 3 days; (ii) treated mares (n = 10) received intrauterine cefquinome for 1 or 3 days. After at least 10 days had passed following the last treatment and ovulation, mares were given Prostaglandin F2α (PGF2α) and were randomly assigned to an alternate treatment. Endometrial biopsy samples were taken at 2, 8, 24 and 48 h, or at 4, 12 and 36 h, after the last treatment. Biopsy samples were taken at the same time points from control mares (n = 2) and lactated Ringer-treated mares (n = 2). Cefquinome concentrations were quantified using a high-performance liquid chromatography (HPLC) assay and inflammation was assessed using haematoxylin and eosin (H&E)-stained sections. Concentrations of cefquinome [559 (1 day) and 595 μg/g (3 days) at 2 h, and 403 (1 day) and 370 μg/g (3 days) at 4 h] were similar between treatment groups at 2 and 4 h after treatment (p > 0.05). At 8 h, as well as at 24 and 48 h, concentrations were greater in the 3-day group (17 vs 301 μg/g, 3 vs 80 μg/g and 0.1 vs 0.2 μg/g, respectively) (p < 0.05). No significant differences (p > 0.05) in the inflammatory response at 2–48 h after treatment were found between groups. 相似文献
87.
Ataxia and paralysis in cats in Australia associated with exposure to an imported gamma-irradiated commercial dry pet food 总被引:1,自引:1,他引:0
Between June 2008 and March 2009, 87 cats in Australia developed symmetrical hindlimb ataxia, paraparesis, tetraparesis, paraplegia or tetraplegia in association with eating an imported, irradiated dry pet food. This communication reports the clinical signs and outcomes of those cats. 相似文献
88.
Y. Q. Yuan L. J. Peelman J. L. Williams A. Van Zeveren A. de Kruif A. Law A. Van Soom 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2004,121(5):356-360
Studying gene expression during the early embryonic stages of in vitro culture is essential and of special interest, not only to gain insights in embryo development but also to find candidate genes that can be used as markers to assess embryo quality. Using differential display RT‐PCR expression of AMPD3 coding for AMP deaminase 3 was found in bovine blastocysts cultured in vitro only under 2% but not under 5 and 20% oxygen tensions. Mapping of this gene to bovine chromosome 15 confirmed its identity. The differential expression of bovine AMPD3 was confirmed by RT‐PCR with specific primers. 相似文献
89.
F López-Gatius P Santolaria JL Yániz JM Garbayo RHF Hunter 《Reproduction in domestic animals》2004,39(6):429-433
The incidence of early foetal loss is increasing under intensive management systems for dairy cattle. The aims of the present study were to determine whether there is any peak period of pregnancy loss during the early foetal period and to evaluate possible differences between single and twin pregnancies. The study population consisted of 1442 pregnant cattle from a single herd. Pregnancy was diagnosed by transrectal ultrasonography between 36 and 42 days after insemination, and then weekly until day 90 of gestation or until pregnancy loss. A total of 1310 cows (90.8%) bore single embryos and 132 (9.2%) carried twins. Pregnancy loss was registered in 139 (9.6%) cows before day 90 of pregnancy: 101 (7.7%) in single and 38 (28.8%) in twin pregnancies. The average time of pregnancy loss for all animals was 58.4 ± 12.6 days and ranged from 45 to 90 days. Seventy‐five per cent of the pregnancy losses were registered between 45 and 60 days of gestation. The average time of pregnancy loss for cows with singletons was 52.1 ± 4.1 days and ranged from 45 to 61 days and that for those with twins was 75.1 ± 12.4 days and ranged from 46 to 90 days. Seventy‐five per cent of the twin pregnancy losses were registered between 68 and 90 days of gestation. Our data show that the foetal loss in singleton pregnancies occurs earlier than in twin pregnancies. Assessment of normal development of gestation on days 60 and 90 after insemination is suggested. 相似文献
90.
JM Morrell B Persson H Tjellström A Laessker H Nilsson M Danilova PV Holmes 《Reproduction in domestic animals》2005,40(6):522-525
In the absence of commercially viable methods for cryopreserving turkey spermatozoa, new processing methods are required to extend the functional life of stored turkey spermatozoa for artificial insemination. The present study evaluates the efficacy of a new extender (Turkey Semen Extend) and investigates the use of density gradient centrifugation in processing turkey spermatozoa for artificial insemination. The new extender is compared with two commercially available turkey semen extenders, Beltsville Poultry Semen Extender and Ovodyl. Turkey spermatozoa in Turkey Semen Extend were still motile 20 h after collection, representing a considerable improvement over the other semen extenders (40%, 0% and 8% for Turkey Semen Extend, Beltsville Poultry Semen Extender and Ovodyl, respectively). A field trial on a commercial turkey farm showed improved fertilization rates following insemination of turkey hens with semen extended in Turkey Semen Extend (89.7%) compared with Beltsville Poultry Semen Extender (86.9%). This difference is statistically significant (p < 0.05). Processing on a density gradient, optimized for turkey spermatozoa, also increased sperm survival (50% gradient-prepared spermatozoa still motile after 18 h compared with <10% non-processed spermatozoa). Preliminary studies indicate that gradient preparation of spermatozoa may aid survival during cryopreservation. 相似文献