全文获取类型
收费全文 | 388篇 |
免费 | 23篇 |
专业分类
林业 | 36篇 |
农学 | 1篇 |
基础科学 | 1篇 |
55篇 | |
综合类 | 34篇 |
农作物 | 8篇 |
水产渔业 | 17篇 |
畜牧兽医 | 237篇 |
园艺 | 6篇 |
植物保护 | 16篇 |
出版年
2021年 | 7篇 |
2020年 | 4篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 16篇 |
2012年 | 19篇 |
2011年 | 27篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 19篇 |
2007年 | 25篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 22篇 |
2003年 | 21篇 |
2002年 | 7篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 3篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1978年 | 3篇 |
1975年 | 4篇 |
1972年 | 6篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1965年 | 3篇 |
1940年 | 2篇 |
1938年 | 2篇 |
1937年 | 3篇 |
1936年 | 3篇 |
1935年 | 3篇 |
1931年 | 3篇 |
1910年 | 2篇 |
1908年 | 2篇 |
排序方式: 共有411条查询结果,搜索用时 234 毫秒
41.
Six novel pyranoanthocyanins were identified by HPLC-ESI-MSn in black carrot (Daucus carota L. ssp. sativus var. atrorubens Alef.) juice. The two major compounds, namely, the vinylcatechol adducts of cyanidin 3-O-(6-O-feruloyl-beta-D-glucopyranosyl)-(1-->6)-[beta-D-xylopyranosyl-(1-->2)]-beta-D-galactopyranoside and cyanidin 3-O-[beta-D-xylopyranosyl-(1-->2)]-beta-D-galactopyranoside, respectively, were isolated by a combination of high-speed countercurrent chromatography with semipreparative HPLC. Their structures were fully elucidated by means of one- and two-dimensional NMR spectroscopy and high-resolution mass spectrometry. The four remaining pigments were characterized as the vinylphenol and vinylguaiacol adducts of cyanidin 3-O-[beta-D-xylopyranosyl-(1-->2)]-beta-D-galactopyranoside, the vinylguaiacol adduct of cyanidin 3-O-(6-O-feruloyl-beta-D-glucopyranosyl)-(1-->6)-[beta-D-xylopyranosyl-(1-->2)]-beta-D-galactopyranoside, and the vinylcatechol adduct of cyanidin 3-O-(6-O-sinapoyl-beta-d-glucopyranosyl)-(1-->6)-[beta-D-xylopyranosyl-(1-->2)]-beta-D-galactopyranoside. These compounds are formed during storage of the juice through the direct reaction of either caffeic, ferulic, or coumaric acid with the respective genuine anthocyanins. 相似文献
42.
Schwarz M Quast P von Baer D Winterhalter P 《Journal of agricultural and food chemistry》2003,51(21):6261-6267
Vitisin A was prepared from malvidin 3-glucoside and pyruvic acid in model wine medium, isolated by countercurrent chromatography, and purified by preparative high-performance liquid chromatography (HPLC). The synthesized compound was used as a reference standard to quantify vitisin A in Chilean wines from Vitis vinifera cv. Cabernet Sauvignon, including a vertical row of wines from the same vineyard over 16 years. Maximum vitisin A content was reached within the first year of storage. Importantly, up to half of the initial amount of vitisin A in young wines was still present in 15 year old wines. Although vitisin A was found to be much more stable as compared to other monomeric C-4 underivatized anthocyanins, it also slowly degrades after reaching its peak concentration. The "color activity concept" was applied to vitisin A, malvidin 3-glucoside, malvidin 3-(6' '-acetylglucoside), and polymeric pigments isolated by countercurrent chromatography in order to estimate their contribution toward the overall color expression of wines. It was found that vitisin A is only a minor contributor to the visually perceived color of aged red wines (color contribution approximately 5%). The major contributor is the polymeric fraction (color contribution approximately 70-90%). 相似文献
43.
44.
A Tanyola? W Meyer M Sa?lam A Ozer Z Ozan S Müftüo?lu R Schwarz 《DTW. Deutsche tier?rztliche Wochenschrift》1989,96(10):498-503
The study describes basic structural aspects of the integumental layers (epidermis, dermis, hypodermis) of the Turkish Angora goat. The results have been obtained by light- and electronmicroscopical methods. Central topics are measurements of layer thickness as related to annual season and life period, as well as typical criteria of integumental layer construction as connected with the hair cycle. Remarkable is a trimerous organization of the dermis and cyclic changes in the thickness of the stratum adiposum of the hypodermis. The findings are discussed with regard to comparable observations from other domestic mammals. 相似文献
45.
46.
47.
P-labelled aminophon, 0,0-di-u-butyl- (1-n-butylaminocyclohexyl) -phosphonate, an agricultural defoliant and siccant, was applied orally in oily solution to lactating cows, 5-6 mg/kg bodymass, resp. The halflifes of degradation in blood serum in vitro are 95 min, of the extractable metabolites in blood, milk and urine 17-20 h. The 0-and 0, N-dealkylcompound of aminophon were found as the preferred metabolites. 相似文献
48.
Johnson VS Corcoran BM Wotton PR Schwarz T Sullivan M 《The Journal of small animal practice》2005,46(8):381-388
OBJECTIVES: To identify features of canine idiopathic pulmonary fibrosis (CIPF) using high-resolution computed tomography (HRCT), and to correlate these features with clinical stages of the disease. METHODS: Ten dogs with signalment, history and clinical signs highly suggestive of CIPF were investigated. Thoracic radiography, haematology and biochemistry profiles, bronchoscopy and bronchoalveolar lavage and HRCT were performed in each case. The dogs were classified as having mild, moderate or severe stages of the disease based on their clinical presentation and radiographic signs. Features identified by HRCT were correlated with these disease stages. RESULTS: HRCT showed a spectrum of pulmonary changes and it was possible to match some of these to the stage of CIPF. CLINICAL SIGNIFICANCE: HRCT is used extensively in humans in the diagnosis and treatment planning of idiopathic pulmonary fibrosis. This preliminary study identifies the high-resolution computed tomographic features of CIPF in a small group of dogs. With further work it may be possible to use HRCT as a non-invasive tool for diagnosing, staging and therapeutically monitoring CIPF. 相似文献
49.
Schwarz T Willis R Summerfield NJ Doust R 《Journal of the American Veterinary Medical Association》2005,226(9):1512-5, 1500
An 8-year-old sexually intact male Golden Retriever with a history of collapse during exercise underwent an examination during which tachydysrhythmia was identified. At another institution, a 12.5-year-old spayed female Lhasa Apso was referred because of a cough and for evaluation of a heart murmur. In the Golden Retriever, radiographic examination revealed bulging of the craniodorsal aspect of the cardiac silhouette and echocardiography revealed right atrial dilatation. In the Lhasa Apso, a cranial mediastinal mass was suspected on the basis of radiographic findings, but no abnormalities were detected echocardiographically. In both dogs, nonselective angiography and contrast-enhanced computed tomography revealed a markedly enlarged, thin-walled right auricle. Exploratory thoracotomy in the Golden Retriever revealed a defect in the pericardium through which the right auricle and part of the atrium had herniated. In dogs, a right auricular aneurysm should be considered in differential diagnoses of a cranial mediastinal mass (detected radiographically) adjacent to the cardiac silhouette. 相似文献
50.
Schwarz E Saalmüller A Gerner W Claus R 《Veterinary immunology and immunopathology》2005,105(1-2):125-139
It is well established that glucocorticoids are key regulators of the immune system and act as immunosuppressive agents in high concentrations. In the pig, effects on the gut immune system and trafficking of lymphocytes between tissues and blood plasma were not investigated so far. Twelve pigs of 70 kg were fed 0.4 mg portions of dexamethasone (Dexa) twice daily for 9 days or remained untreated (controls) and were sacrificed for tissue collection at the end of Dexa treatment. Another six pigs with jugular vein catheters were left untreated for 7 days (control period) and then received Dexa for 9 days. Blood was drawn twice during the control period and at days 3, 6 and 9 of the Dexa period for characterization of peripheral blood leukocytes. Cells were obtained from thymus, mesenteric lymph nodes, jejunal mucosa and Peyer's patches. Lymphoid cells from gut tissue were isolated from two fractions: the EDTA-fraction, containing the intraepithelial lymphocytes (IEL), and the Collagenase-fraction, containing the lamina propria lymphocytes (LPL). In all samples, cell counts and phenotypic characterization of cells by flow cytometry (FCM) were performed. In thymus, Dexa led to a more than 90% reduction of the absolute cell number, which was mainly found in the CD4+CD8+ subpopulation. Dexa effects on lymphocytes from mesenteric lymph nodes were less severe (50%) and led mainly to a decrease (71%) of B-lymphocytes. The number of lymphocytes in the EDTA-fraction (IEL) of the jejunal mucosa decreased significantly by 56% in the Dexa-treated animals compared to the controls, whereas the number of lymphocytes in the Collagenase-fraction (LPL) decreased only moderately. In the Peyer's patches, a decreasing tendency in the number of lymphocytes in the EDTA-fraction was observed which, however, was not significant. In blood, monocytes and granulocytes were significantly increased in an order of 60%. The data show that supraphysiological amounts of Dexa remarkably reduce cell numbers in thymus and also in the intraepithelial compartment of the jejunal mucosa and ileal Peyer's patches. In blood, a notable homeostasis was observed for several leukocyte populations whereas both monocytes and granulocytes increased. 相似文献