全文获取类型
收费全文 | 76439篇 |
免费 | 3765篇 |
国内免费 | 52篇 |
专业分类
林业 | 3597篇 |
农学 | 2342篇 |
基础科学 | 392篇 |
7916篇 | |
综合类 | 15524篇 |
农作物 | 3080篇 |
水产渔业 | 3402篇 |
畜牧兽医 | 38529篇 |
园艺 | 904篇 |
植物保护 | 4570篇 |
出版年
2018年 | 856篇 |
2017年 | 925篇 |
2016年 | 858篇 |
2015年 | 781篇 |
2014年 | 952篇 |
2013年 | 2604篇 |
2012年 | 1680篇 |
2011年 | 2069篇 |
2010年 | 1359篇 |
2009年 | 1285篇 |
2008年 | 2038篇 |
2007年 | 2076篇 |
2006年 | 1894篇 |
2005年 | 1831篇 |
2004年 | 1753篇 |
2003年 | 1784篇 |
2002年 | 1690篇 |
2001年 | 2216篇 |
2000年 | 2219篇 |
1999年 | 1848篇 |
1998年 | 701篇 |
1997年 | 699篇 |
1995年 | 813篇 |
1993年 | 697篇 |
1992年 | 1490篇 |
1991年 | 1551篇 |
1990年 | 1666篇 |
1989年 | 1646篇 |
1988年 | 1528篇 |
1987年 | 1478篇 |
1986年 | 1530篇 |
1985年 | 1515篇 |
1984年 | 1247篇 |
1983年 | 1144篇 |
1982年 | 771篇 |
1981年 | 717篇 |
1979年 | 1248篇 |
1978年 | 979篇 |
1977年 | 848篇 |
1976年 | 803篇 |
1975年 | 913篇 |
1974年 | 1201篇 |
1973年 | 1240篇 |
1972年 | 1255篇 |
1971年 | 1182篇 |
1970年 | 1102篇 |
1969年 | 1003篇 |
1968年 | 863篇 |
1967年 | 906篇 |
1966年 | 838篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Pharmacokinetic assessment of the monepantel plus oxfendazole combined administration in dairy cows 下载免费PDF全文
M. Ballent P. Viviani F. Imperiale P. Dominguez S. Halwachs H. Mahnke W. Honscha C. Lanusse G. Virkel A. Lifschitz 《Journal of veterinary pharmacology and therapeutics》2018,41(2):292-300
Monepantel (MNP) is a novel anthelmintic compound launched into the veterinary pharmaceutical market. MNP is not licenced for use in dairy animals due to the prolonged elimination of its metabolite monepantel sulphone (MNPSO2) into milk. The goal of this study was to evaluate the presence of potential in vivo drug‐drug interactions affecting the pattern of milk excretion after the coadministration of the anthelmintics MNP and oxfendazole (OFZ) to lactating dairy cows. The concentrations of both parent drugs and their metabolites were measured in plasma and milk samples by HPLC. MNPSO2 was the main metabolite recovered from plasma and milk after oral administration of MNP. A high distribution of MNPSO2 into milk was observed. The milk‐to‐plasma ratio (M/P ratio) for this metabolite was equal to 6.75. Conversely, the M/P ratio of OFZ was 1.26. Plasma concentration profiles of MNP and MNPSO2 were not modified in the presence of OFZ. The pattern of MNPSO2 excretion into milk was also unchanged in animals receiving MNP plus OFZ. The percentage of the total administered dose recovered from milk was 0.09 ± 0.04% (MNP) and 2.79 ± 1.54% (MNPSO2) after the administration of MNP alone and 0.06 ± 0.04% (MNP) and 2.34 ± 1.38% (MNPSO2) after the combined treatment. The presence of MNP did not alter the plasma and milk disposition kinetics of OFZ. The concentrations of the metabolite fenbendazole sulphone tended to be slightly higher in the coadministered group. Although from a pharmacodynamic point of view the coadministration of MNP and OFZ may be a useful tool, the presence of OFZ did not modify the in vivo pharmacokinetic behaviour of MNP and therefore did not result in reduced milk concentrations of MNPSO2. 相似文献
982.
983.
984.
C. P. DELLO F. M. BELPAIRE A. DE RICK† N. H. FRAEYMAN 《Journal of veterinary pharmacology and therapeutics》1988,11(1):71-76
The concentration and the heterogeneity of alpha-1-acid glycoprotein (alpha-1-AGP) and oxprenolol binding were determined in serum of healthy dogs and dogs with inflammatory disease. In inflammation, an increase in the mean alpha-1-AGP concentration from 0.47 to 2.85 g/l was accompanied by a reduction in the mean free oxprenolol fraction from 25% to 6%. alpha-1-AGP concentration and oxprenolol binding were inversely correlated. The heterogeneity of canine alpha-1-AGP remained essentially unchanged in dogs with inflammation and, in both these dogs and the controls, between five and seven forms with different isoelectric points and one single concanavalin A-reactive form were detected. It is concluded that in dogs, as in humans, oxprenolol binds to serum alpha-1-AGP. Changes in serum binding of oxprenolol during inflammation result from a change in the serum concentration of alpha-1-AGP rather than a change of molecular heterogeneity. 相似文献
985.
A strain of Escherichia coli isolated from the yolk sac of stunted turkey poults was administered orally to day-old large white poults. Poults were inoculated with either 0.1 ml of sterile broth or 0.1 ml of a 10(-2) dilution of a 24-hr E. coli culture containing 3.4 x 10(8) viable bacteria per ml. Two levels of dietary protein (28 or 22%) were fed from 1 day to 3 weeks of age. Following E. coli inoculation of 3.4 x 10(5) viable bacteria at day one, body weight gain and feed consumption from 0 to 3 weeks of age were numerically increased 4.5 and 2.1%, respectively, and feed efficiency was significantly increased 2.4%. E. coli had a greater effect on performance of poults fed the 28% protein diet than on poults fed the 22% protein diet. Metabolism studies, conducted from 7 to 10 and from 17 to 20 days postinoculation, showed no significant changes in the measurements of nutrient utilization due to E. coli other than a 17% increase in nitrogen retention from 17 to 20 days by those poults fed the 28% protein diet. 相似文献
986.
In a feeding experiment (54 piglets) and a slaughtering test for the registration of tract and digesta properties (15 piglets) the influence of rations with 69% rye (R) or wheat (W) with and without a supplement of 200 mg of the chinoxalin derivate Bisergon/kg DM (rations RB and WB) was studied. In the sequence R, RB, W and WB the feed intake in the test period of 3 weeks after weaning amounted to 581, 651, 583 and 764 g, weight gain to 314, 365, 319 and 424 g per animal and day. In the same sequence the concentration of organic acids in the stomach amounted to 41, 5, 25 and 18 mmol per 100 g dry matter and in the colon to 106, 83, 64 and 62. Bisergon caused a redistribution of the digesta from the stomach to the large intestine and a more rapid emptying of the stomach as well. Rye caused extreme fermentation processes in the front part of the tract and Bisergon clearly has ergotropic qualities for the stabilization of the intestinal flora. 相似文献
987.
Curtis G. Schelling MS VMD Jeffrey A. Wortman VMD PhD H. Mark Saunders VMD 《Veterinary radiology & ultrasound》1988,29(5):227-233
Ultrasonographic findings of splenic infarction and necrosis in three dogs are presented. Two previously unreported ultrasonographic patterns are identified: (1) Focal, hypoechoic or isoechoic, circular, wellmarginated nodular masses with peripheral lesions causing deformation of the splenic margin. (2) Diffuse hypoechoic or heteroechoic coarse/"lacy" parenchymal pattern with no deformation of margin. The presence of gas within the splenic parenchyma of one dog was detected by both radiography and ultrasonography. Ultrasonographic patterns of splenic infarction in both man and the dog are discussed 相似文献
988.
Bruno H. Pypendop Kristine T. Siao M.G. Ranasinghe Kirby Pasloske 《Veterinary anaesthesia and analgesia》2018,45(3):269-277
Objective
To determine the effective plasma alfaxalone concentration for the production of immobility in cats.Study design
Prospective up-and-down study.Animals
Sixteen 1–2 year old male castrated research cats.Methods
Cats were instrumented with catheters in a jugular and a medial saphenous vein. Alfaxalone was administered via the medial saphenous catheter, using a target-controlled infusion system. The infusion lasted for approximately 32 minutes. A noxious stimulus (tail clamp) was applied 30 minutes after starting the alfaxalone infusion, until the cat moved or 60 seconds had elapsed, whichever occurred first. The target alfaxalone concentration was set at 5 mg L?1 in the first cat and increased or decreased by 1 mg L?1 in subsequent cats, if the previous cat had moved or not moved in response to stimulation, respectively. This was continued until six independent crossovers (different responses in pairs of subsequent cats) had been observed. Blood samples were collected before alfaxalone administration, and 15 and 31 minutes after starting the administration, for the determination of plasma alfaxalone concentration using liquid chromatography/tandem mass spectrometry. The alfaxalone concentration yielding a probability of immobility in 50% (EC50), 95% (EC95) and 99% (EC99) of the population, and their respective 95% Wald confidence intervals were calculated.Results
The EC50, EC95 and EC99 for alfaxalone-induced immobility were 3.7 (2.4–4.9), 6.2 (4.7–) and 7.6 (5.5–) mg L?1, respectively.Conclusions and clinical relevance
The effective plasma alfaxalone concentration for immobility in cats was determined. This value will help in the design of pharmacokinetic-based dosing regimens. 相似文献989.
Antognoli MC Garry FB Hirst HL Lombard JE Dennis MM Gould DH Salman MD 《Veterinary microbiology》2008,127(3-4):300-308
Mycobacterium avium subspecies paratuberculosis (MAP) disseminated infection in dairy cattle affects animal health and productivity and is also a potential public health concern. The study objectives were to characterize MAP disseminated infection in dairy cattle and to determine the role of antemortem tests in detecting cattle with disseminated infection. Forty culled dairy cows representing a variety of serum enzyme-linked immunosorbent assay (ELISA) results and body conditions were selected for the study. The physical condition of the cows was assessed via clinical examination prior to euthanasia and blood and feces were collected and tested by serum ELISA and fecal culture, respectively. Fifteen tissues were aseptically collected from each cow during necropsy and cultured for isolation of MAP. Disseminated infection was diagnosed when MAP was isolated in tissues other than the intestines or their associated lymph nodes (LNs) and was distinguished from infection found only in the gastrointestinal tissues and from absence of infection. Of the 40 cows in the study, 21 had MAP disseminated infection. Results showed that 57% (12/21) of cows with disseminated infection had average to heavy body condition and no diarrhea. Cows with disseminated infection had no to minimal gross pathologic evidence of infection in 37% (8/21) of cases. Only 76% (16/21) of cows with disseminated infection had positive historical ELISA results and only 62% (13/21) had a positive ELISA at slaughter. Thus, antemortem evidence of MAP infection was lacking in a high proportion of cows where MAP disseminated infection was confirmed. 相似文献
990.
In 2005, a prion disease identified in a goat from France was reported to be consistent with disease from the bovine spongiform encephalopathy (BSE) agent. Subsequent retrospective examination of UK goat scrapie cases led to the identification of one potentially similar, but as yet unconfirmed, case from Scotland. These findings strengthened concerns that small ruminant populations exposed to the BSE agent have become infected. The lack of data relating specifically to scrapie in goats has been contributory to past assumptions that, in general, sheep and goats respond similarly to prion infections. In this study, brain material from 22 archived caprine scrapie cases from the UK was reviewed by histopathology and by immunohistochemical examination for accumulations of disease-specific prion protein (PrP(Sc)) to provide additional data on the lesions of caprine scrapie and to identify any BSE-like features. The vacuolar change observed in the goats was characteristic of transmissible spongiform encephalopathies in general. PrP(Sc) immunohistochemical morphologic forms described in scrapie and experimental BSE infections of sheep were demonstrable in the goats, but these were generally more extensive and variable in PrP(Sc) accumulation. None of the cases examined showed a PrP(Sc) immunohistochemical pattern indicative of BSE. 相似文献