全文获取类型
收费全文 | 1277篇 |
免费 | 79篇 |
专业分类
林业 | 21篇 |
农学 | 24篇 |
基础科学 | 7篇 |
83篇 | |
综合类 | 274篇 |
农作物 | 42篇 |
水产渔业 | 43篇 |
畜牧兽医 | 763篇 |
园艺 | 23篇 |
植物保护 | 76篇 |
出版年
2017年 | 11篇 |
2016年 | 18篇 |
2015年 | 17篇 |
2014年 | 13篇 |
2013年 | 36篇 |
2012年 | 35篇 |
2011年 | 50篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 36篇 |
2007年 | 28篇 |
2006年 | 41篇 |
2005年 | 39篇 |
2004年 | 25篇 |
2003年 | 30篇 |
2002年 | 30篇 |
2001年 | 34篇 |
2000年 | 33篇 |
1999年 | 27篇 |
1998年 | 22篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 16篇 |
1994年 | 18篇 |
1993年 | 13篇 |
1992年 | 34篇 |
1991年 | 30篇 |
1990年 | 25篇 |
1989年 | 37篇 |
1988年 | 30篇 |
1987年 | 36篇 |
1986年 | 33篇 |
1985年 | 29篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1979年 | 15篇 |
1978年 | 13篇 |
1976年 | 15篇 |
1975年 | 20篇 |
1974年 | 31篇 |
1973年 | 24篇 |
1972年 | 22篇 |
1971年 | 20篇 |
1970年 | 20篇 |
1969年 | 16篇 |
1968年 | 14篇 |
1967年 | 13篇 |
1966年 | 16篇 |
排序方式: 共有1356条查询结果,搜索用时 62 毫秒
1.
Shay Allred Wenjie Shao Jacob H. Jones M. Wes Schilling Beth H. Baker Peter J. Allen 《Aquaculture Research》2020,51(5):1854-1866
Catfish Ictalurus spp. are subjected to stressful conditions during harvest, which may be linked to fillet coloration and quality. Poor water quality in ponds, socks or hauling tanks, as well as handling stress, have been suggested to cause red fillets in catfish; however, chronic exposure has not resulted in red fillets. Short‐term occurrences of extreme poor water quality, particularly low dissolved oxygen, high carbon dioxide and high temperature, may occur in ponds or during harvest. Therefore, market‐sized Channel Catfish Ictalurus punctatus were acutely exposed (12 hr) to one of the three water quality treatments while confined during a simulated socking procedure and evaluated for stress responses by means of change in blood parameters and fillet quality. In fish subjected to the extreme treatment, hematocrit, plasma cortisol, glucose and lactate levels increased, with 22% mortality, indicating highly stressful conditions. In fish subjected to moderate and typical (control) treatments, cortisol increased but a lack of change or decrease in glucose and lactate indicated minimal anaerobic metabolism. Only one red fillet was produced by the extreme treatment and two by the typical treatment; therefore, the results suggest red fillets are not a product of poor water quality compounded by handling during harvest. 相似文献
2.
ABSTRACTAims: To determine if an ELISA for measurement of IgA in equine serum could be used to measure concentrations of IgA in foal faeces and to determine correlations with concentrations in the milk of the dam.Methods: Faeces from 20 Welsh Cob and Welsh Pony foals and milk from their dams were collected within 12?hours (Day 0) and at 6 days after parturition (Day 6). On Day 6, faeces could not be collected from 2/20 foals, and milk samples could not be collected from 3/20 mares. An equine IgA ELISA validated for serum and plasma was used to measure concentrations of IgA in all samples in triplicate. The precision of the assay for each sample type was determined using modified CV.Results: IgA was not detectable in 7/20 Day 0 faecal samples and in 2/18 Day 6 faecal samples. For samples with detectable IgA, the mean modified CV was 10.5 (95% CI?=?6.0–15.0)% for Day 0 faecal samples, and was 6.8 (95% CI?=?4.3–9.4)% for Day 6 faecal samples. Median concentrations of IgA in faeces on Day 0 were lower than concentrations on Day 6 (0.7?mg/g vs. 37?mg/g dry matter; p?=?0.003). Concentrations of IgA in milk and faeces on Day 6 were statistically correlated (r?=?0.59; p?=?0.006).Conclusions and clinical relevance: The IgA ELISA showed acceptable precision when used to estimate concentrations of IgA in foal faeces during the first week of life, but IgA could not be detected in 37% of meconium samples collected on Day 0. This assay may be useful for investigation of the role of maternal milk IgA in the gastrointestinal tract of neonatal foals, but further assessment of both accuracy and precision of the ELISA is required. 相似文献
3.
Immunohistochemical Expression of Growth Factors in the Follicular Wall of Normal and Cystic Ovaries of Sows 下载免费PDF全文
FJF Sant'Ana JL Reis Junior GR Blume EJ Gimeno F Rey HH Ortega 《Reproduction in domestic animals》2015,50(2):327-332
The expression of growth factors was evaluated immunohistochemically in normal and cystic ovaries of sows. The immunohistochemically stained area (IHCSA) was quantified by image analysis to analyse the expression of these proteins in the follicular wall of secondary, tertiary and cystic follicles. IGF‐I immunoreactivity was strong in the granulosa cell layer (GC), moderate in the theca interna (TI) and mild in the theca externa (TE) of the normal follicles. There was severe reduction of the labelling to IGF‐I in the GC of the follicular and luteinized cysts. In the normal follicles, the reactivity for IGF‐II was very similar to pattern noted in IGF‐I. There was reduction of the IHCSAs in the GC of the follicular and luteinized cysts, but the decrease was not significant. The staining of the IGF‐II in the TI and TE of the cysts was increased, in comparison with normal follicles. The IHCSAs for VEGF were higher in the GC and TE of the normal follicles in contrast to TI, but this difference was noted only in the tertiary follicle. The VEGF reactivity increased in the GC of the cysts, in relation to normal follicles. The results of the current study show that the formation of ovarian cysts in sows is associated with alterations in the immunohistochemical expression of some growth factors. 相似文献
4.
Ben C Maddison John Spiropoulos Christopher M Vickery Richard Lockey Jonathan P Owen Keith Bishop Claire A Baker Kevin C Gough 《Veterinary research》2015,46(1)
Ovine scrapie can be transmitted via environmental reservoirs. A pool of ovine scrapie isolates were incubated on soil for one day or thirteen months and eluted prion was used to challenge tg338 mice transgenic for ovine PrP. After one-day incubation on soil, two PrPSc phenotypes were present: G338 or Apl338ii. Thirteen months later some divergent PrPSc phenotypes were seen: a mixture of Apl338ii with either G338 or P338, and a completely novel PrPSc deposition, designated Cag338. The data show that prolonged ageing of scrapie prions within an environmental matrix may result in changes in the dominant PrPSc biological/biochemical properties. 相似文献
5.
6.
Charlotte M. Keenan Julia F. Baker Alys E. Bradley Dawn G. Goodman Takanori Harada Ronald Herbert Wolfgang Kaufmann Rupert Kellner Beth Mahler Emily Meseck Thomas Nolte Susanne Rittinghausen John Vahle Katsuhiko Yoshizawa 《Journal of toxicologic pathology》2015,28(1):51-53
The INHAND Proposal (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) has been operational since 2005. A Global Editorial Steering Committee (GESC) manages the overall objectives of the project and the development of harmonized terminology for each organ system is the responsibility of the Organ Working Groups (OWG), drawing upon experts from North America, Europe and Japan.Great progress has been made with 9 systems published to date – Respiratory, Hepatobiliary, Urinary, Central/Peripheral Nervous Systems, Male Reproductive and Mammary, Zymbals, Clitoral and Preputial Glands in Toxicologic Pathology and the Integument and Soft Tissue and Female Reproductive System in the Journal of Toxicologic Pathology as supplements and on a web site – www.goreni.org. INHAND nomenclature guides offer diagnostic criteria and guidelines for recording lesions observed in rodent toxicity and carcinogenicity studies. The guides provide representative photo-micrographs of morphologic changes, information regarding pathogenesis, and key references. During 2012, INHAND GESC representatives attended meetings with representatives of the FDA Center for Drug Evaluation and Research (CDER), Clinical Data Interchange Standards Consortium (CDISC), and the National Cancer Institute (NCI) Enterprise Vocabulary Services (EVS) to begin incorporation of INHAND terminology as preferred terminology for SEND (Standard for Exchange of Nonclinical Data) submissions to the FDA. The interest in utilizing the INHAND nomenclature, based on input from industry and government toxicologists as well as information technology specialists, suggests that there will be wide acceptance of this nomenclature. The purpose of this publication is to provide an update on the progress of INHAND. 相似文献
7.
Summary Gibberellins were extracted from seeds and green plants of different sex types of the closely related species Cucumis sativus L. (cucumber) and C. melo L. (muskmelon). Both seeds and green plants of monoecious and andromonoecious lines of C. sativus contained significantly higher gibberellin levels at all growth stages tested than did a gynoecious line. Gibberellin activity in the monoecious and andromonoecious C. sativus line reached a maximum at the growth stage corresponding to flower differentiation at cotyledonary and first leaf axils. Vernalization of seeds of gynoecious plants resulted in increased male tendency correlated with increased gibberellin activity. In contrast, monoecious and andromonoecious lines of C. melo were gibberellin deficient relative to hermaphroditic and gynoecious lines.Journal Article No 5534 from the Michigan Agricultural Experiment Station. This work was supported by a grant from the Herman Frasch Foundation. 相似文献
8.
AE Domínguez‐Rebolledo F Martínez‐Pastor AF Bisbal JL Ros‐Santaella O García‐Álvarez A Maroto‐Morales AJ Soler JJ Garde MR Fernández‐Santos 《Reproduction in domestic animals》2011,46(3):393-403
Oxidative stress represents a challenge during sperm manipulation. We have tested the effect of increasing hydrogen peroxide (H2O2) levels on red deer spermatozoa after cryopreservation, and the role of male‐to‐male variation in that response. In a first experiment, eight thawed samples were submitted to 0, 25, 50, 100 and 200 μm H2O2 for 2 h at 37°C. Intracellular reactive oxygen species (H2DCFDA‐CM) increased with H2O2 concentration, but we only detected a decrease in sperm function (motility by CASA and chromatin damage by sperm chromatin structure assay) with 200 μm . Lipoperoxidation assessed by the thiobarbituric acid reactive substance (TBARS) method increased slightly with 50 μm H2O2 and above. In a second experiment, samples from seven males were submitted to 0 and 200 μm H2O2 for 2 h, triplicating the experiment within each male. Males differed at thawing and regarding their response to incubation and H2O2 presence. We found that the kinematic parameters reflected male‐to‐male variability, whereas the response of the different males was similar for lipid peroxidation and viability. A multiparametric analysis showed that males grouped differently if samples were assessed after thawing, after incubation without H2O2 or after incubation with H2O2. Red deer spermatozoa are relatively resilient to H2O2 after thawing, but it seems to be a great male‐to‐male variability regarding the response to oxidative stress. The acknowledgement of this individual variability might improve the development of optimized sperm work protocols. 相似文献
9.
10.
Composition and proposed structure of a water-soluble glycan from the Keumsa Sangwhang Mushroom (Phellinus linteus) 总被引:1,自引:0,他引:1
Phellinus linteus is a mushroom which has been prized in Korea for its medicinal properties since ancient times. A glycan preparation from this source has shown promise in experimental anti-tumour and metastasis studies, but the glycan has not been well characterized. In the present work, the glycan fraction of a hot water extract from P. linteus (Keumsa Sangwhang Mushroom, Korea) has been isolated following ammonium sulfate precipitation, dialysis/concentration and anion exchange chromatographic steps. Analyses for monosaccharide composition showed glucose and mannose to be the major constituents. Digestion of the glycan fraction with specific glycosidases and by linkage analysis allowed us to propose a core beta(1-3) linked glucan heavily substituted via (1-6) links with beta(1-3) linked mannose chains. Significant levels of galactose and xylose, present in the glycan fraction, may be associated with this glucomannan or not. These findings are consistent with the view that a core beta(1-3)-linked glucan chain with beta(1-6) branch points is a common feature of mushroom glycans possessing anti-tumour activity. 相似文献