全文获取类型
收费全文 | 1275篇 |
免费 | 103篇 |
专业分类
林业 | 121篇 |
农学 | 42篇 |
基础科学 | 2篇 |
301篇 | |
综合类 | 22篇 |
农作物 | 77篇 |
水产渔业 | 63篇 |
畜牧兽医 | 622篇 |
园艺 | 24篇 |
植物保护 | 104篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 37篇 |
2020年 | 39篇 |
2019年 | 27篇 |
2018年 | 71篇 |
2017年 | 74篇 |
2016年 | 76篇 |
2015年 | 56篇 |
2014年 | 58篇 |
2013年 | 80篇 |
2012年 | 100篇 |
2011年 | 96篇 |
2010年 | 79篇 |
2009年 | 31篇 |
2008年 | 61篇 |
2007年 | 60篇 |
2006年 | 44篇 |
2005年 | 47篇 |
2004年 | 50篇 |
2003年 | 37篇 |
2002年 | 51篇 |
2001年 | 19篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1977年 | 4篇 |
1976年 | 11篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有1378条查询结果,搜索用时 15 毫秒
61.
K W Romański 《Archives of Animal Nutrition》2002,56(6):393-408
The presented study was designed to elucidate whether the cholinergic mechanisms control ovine antral slow waves in various physiological conditions, including feeding and various phases of migrating myoelectric complex (MMC). The investigations were carried out on six adult sheep of Polish Merino breed with seven bipolar electrodes surgically implanted onto the antral and small intestinal wall. In the course of chronic experiments, the myoelectric activity was recorded from these regions using the multichannel electroencephalograph. Experiments were performed on 48 h fasted and non-fasted animals. During some of these experiments, sheep were fed with standard fodder. During control experiments 0.15 M NaCl was slowly administered i.v. through the indwelling catheter and during other experiment, hexamethonium bromide (2.0 and 5.0 mg/kg). atropine sulfate (0.02; 0.1; 0.5 and 1.5 mg/kg) and pirenzepine dihydrochloride (0.02; 0.5 and 2.0 mg/kg) were administered i.v. during phase 1-2a or 2b MMC. The drugs were also given in combinations. The recordings were analysed and the antral slow wave amplitudes and frequencies were calculated. Unlike the slow wave amplitude, either feeding or the anticholinergic drugs significantly increased slow wave frequency, especially when the given procedure was started during phase 2b MMC. The most pronounced effects were observed after hexamethonium given alone or in combinations. Thus, the cholinergic system modulates antral slow wave frequency in sheep. 相似文献
62.
Both resiniferatoxin (RTX) and tetrodotoxin (TTX) have been reported to be effective in several clinical trials aiming to cure urinary bladder dysfunction. The goal of this experiment was to study the effect of intravesical administration of RTX and TTX on the chemical coding of paracervical ganglion (PCG) neurons that supply the urinary bladder in pigs. The vasoactive intestinal peptide (VIP) and the opioid family member Leu5-enkephalin (LENK) are both known for their regulatory effects in the function of the porcine genitourinary tract. The PCG neurons innervating the urinary bladder were identified by application of the retrograde tracer Fast Blue (FB), injected into the bladder wall prior to intravesical RTX or TTX administration. Immunocytochemical detection of LENK and VIP expression in the FB-labelled perikarya revealed that in the control group 25.15% of the FB-positive PCG neurons contained LENK, and 9.22% of them expressed VIP. Intravesical infusion of RTX resulted in an increase in the number of LENKIR neurons to 48.19% and VIP-IR perikarya to 11.25%. Optional treatment with TTX induced increase of LENK-IR neurons up to 81.67% and VIP-IR population to 16.46% of the FB-positive PCG cells. The present results show that both neurotoxins affect the chemical coding of PCG nervous cells supplying the porcine urinary bladder and that they stimulate both LENK and VIP expression. Furthermore, the results indicate a possible involvement of LENK and VIP neurons in the mechanisms of action of RTX and TTX in the therapy of overactive bladder disorder. 相似文献
63.
Falandysz J Lipka K Kawano M Brzostowski A Dadej M Jedrusiak A Puzyn T 《Journal of agricultural and food chemistry》2003,51(9):2832-2836
Total concentrations of mercury were determined using cold-vapor atomic absorption spectroscopy (CV-AAS) in the fruiting bodies of 16 species of wild mushrooms and underlying soil (0-10 cm) substrates collected in the areas of the Communes of Morag and ?ukta in the county of Ostróda in northeastern Poland in 1997-1998. A total of 174 composite samples of caps, 174 stalks, 80 whole fruiting bodies (collectively 1254 specimens), and 252 soils were examined. Among several species of mushrooms analyzed, the greatest concentrations were between 1300 and 71000 ng.g(-1) of dry matter. These levels were found in the caps of Sweating mushroom (Clitocybe rivulosa), King Bolete (Boletus edulis), and Common Puffball (Lycoperdon perlatum) and also were characterized by the highest bioconcentration factors (BCF) for Hg, which ranged between 160 +/- 82 and 110 +/- 34. The cap to stalk quotient for mercury concentrations was approximately 2 for most of the species except Poison Pax (Paxilus involutus), which had a greater concentration in caps than in stalks and a quotient of 4.4 +/- 7.2. Hg concentrations in the underlying soil substrates (0-10 cm layer) ranged between 21 +/- 21 and 390 +/- 130 ng.g(-1) of dry matter. The results showed that the consumption of mushrooms, considered to be the sole dietary source of mercury at the highest or mean element concentrations found, is not hazardous at daily ingestion rates of less than 70 and 210 g of fresh product, which would result in a hazard index value of less than unity. 相似文献
64.
Pharmacokinetic investigations of the marker active metabolites 4‐methylamino‐antipyrine and 4‐amino‐antipyrine after intramuscular injection of metamizole in healthy piglets 下载免费PDF全文
A. Burmańczuk C. Kowalski M. Giorgi H. Owen T. Grabowski 《Journal of veterinary pharmacology and therapeutics》2016,39(6):616-620
Metamizole (MT) is a pyrazolone nonsteroidal anti‐inflammatory drug labelled for humans and animals. The aim of this study was to assess the pharmacokinetics of its active metabolites 4‐methylamino‐antipyrine (MAA) and 4‐amino‐antipyrine (AA) in male piglets after a single intramuscular injection of MT. Eight healthy male piglets were administered MT (100 mg/kg) intramuscularly. Blood was sampled at scheduled time intervals, and drug plasma concentrations evaluated by a validated HPLC method. MAA and AA plasma concentrations were quantitatively detectable from 0.25 to 48 h and 0.50 to 72 h, respectively, in 6 of 8 and 7 of 8 animals. The average maximum concentrations of MAA and AA were of 47.59 and 4.94 mg/mL, respectively. The average half‐lives were 8.57 and 13.3 h for MAA and AA, respectively. This study showed that the amount of MAA and AA produced in piglets is different to that in the animal species previously investigated. Further studies are necessary to understand whether these differences in MAA and AA plasma concentrations between animal species necessitate diverse therapeutic drug dosing. 相似文献
65.
Paśko P Zagrodzki P Bartoń H Chłopicka J Gorinstein S 《Plant foods for human nutrition (Dordrecht, Netherlands)》2010,65(4):333-338
The effect of Chenopodium quinoa seeds on lipid profile, glucose level, protein metabolism and selected essential elements (Na, K, Ca, Mg) level was determined
in high—fructose fed male Wistar rats. Fructose decreased significantly LDL [42%, p < 0.01] and activity of alkaline phosphatase [20%, p < 0.05], and increased triglycerides level [86%, p < 0.01]. The analysis of blood of rats fed quinoa indicated, that these seeds effectively reduced serum total cholesterol
[26%, p < 0.05], LDL [57%, p < 0.008] and triglycerides [11%, p < 0.05] when compared to the control group. Quinoa seeds also significantly reduced the level of glucose [10%, p < 0.01] and plasma total protein level [16%, p < 0.001]. Fructose significantly decreased HDL [15%, p < 0.05] level in control group but when the quinoa seeds were added into the diet the decrease of HDL level was inhibited.
Quinoa seeds did not prevent any adverse effect of increasing triglyceride level caused by fructose. It was shown in this
study that quinoa seeds can reduce most of the adverse effects exerted by fructose on lipid profile and glucose level. 相似文献
66.
67.
Seasonal variations in beta carotene intake and low levels of beta carotene and vitamin A in blood plasma were found in cows fed ration based mainly on maize silage. The supplementation of daily winter rations with 300 mg Rovimix-beta carotene per cow, beginning 14 days before parturition and 60 days after calving increased slighty the beta carotene and vitamin A concentrations of blood plasma and improved some fertility indices: the number of inseminations per cow was reduced and the percentage of conception rate was significantly higher. It may be assumed that beta carotene content in feeds and it's utilization rate generally reflected in beta carotene blood plasma level and in the improvement of fertility. 相似文献
68.
M Rakowska T Zebrowska M Neumann K Medyńska K Raczyńska-Bojanowska 《Archives of Animal Nutrition》1990,40(8):695-701
Six pigs of initial weight 40 +/- 1.7 kg with a T-piece cannula fitted at the terminal ileum were given diets composed of 96.3% of rye, barley or triticum grains ground to pass the 2.6 mm mesh, 3.3% mineral and vitamin mixture and 0.4% Cr2O3. Each diet was given to all pigs in a Latin square design, and faeces and ileal digesta were collected on 7, 8, 9 and 10, 11 and 12 day of feeding each diet, respectively. The grains varied widely in the content of pentosans, polyuroids, beta-glucan and monosaccharides. The antitrypsin activities were 0.84, 2.73 and 1.62 TUI/g in barley, rye and triticum, respectively. Ileal and faecal apparent digestibilities of nitrogen and amino acids were higher (P less than or equal to 0.01) in Triticum than in barley and rye. The digestibility of carbohydrates (pentosans, beta-glucan, polyuroids and non-structural carbohydrates) were lower in pigs fed a rye diet than of those fed a Triticum diet. The results are discussed with respect of the role to non starch polysaccharides, especially pentosans in digestibility of nitrogen and energy in animals receiving a rye diet. 相似文献
69.
In a field study, the composition and concentrations of amino compounds in the xylem sap of the mistletoe, Viscum album L., and in the xylem sap of two host species, an evergreen conifer (Abies alba Mill.) and a deciduous broad-leaved tree (Populus x euramericana), were analyzed. The xylem sap of both hosts and mistletoe contained large, but similar amounts of total organic nitrogen in low molecular weight amino compounds (TONLW). Nevertheless, individual amino compounds accumulated in the xylem sap of mistletoe relative to the host xylem sap, indicating selective uptake. In the xylem sap of Populus, major amino compounds (asparagine (Asn) and glutamine (Gln)) and the bulk parameters, TONLW and proteinogenic amino acids, showed significant seasonal variation. In Abies and in mistletoe on either host, variation of amino compounds in xylem sap was largely explained by inter-annual differences, not by seasonal variation. In both hosts, TONLW in the xylem sap was dominated by Gln. There was a steady decrease in relative abundance of Gln from the host xylem sap to the mistletoe xylem sap and to the stems and leaves of mistletoe. Simultaneously, the abundance of arginine (Arg) increased. Arginine was the predominant amino compound in the stems and leaves of mistletoe, occurring at concentrations previously observed only in leaves of trees exposed to excess nitrogen. We conclude that Gln (2 mol N mol(-1)) delivered by the host xylem sap is converted, in mistletoe, to Arg (4 mol N mol(-1)) and that the organic carbon liberated from Gln contributes significantly to the parasite's heterotrophic carbon gain. Statistical analyses of the data support this conclusion. Accumulation of Arg in mistletoe is an indication of excess N supply as a result of the uptake of amino compounds from the host xylem sap and a lack of phloem uploading. 相似文献
70.
Małgorzata Skrzypczyńska 《Journal of pest science》2001,74(1):11-12
Analytical studies were conducted on the species composition of galls occurring on the leaves of Salix purpurea L. in the Ojców National Park in 1999?–?2000. The species composition of galls was identical in two consecutive years. Galls were caused by 5?species (a total of 480?galls). The most numerous species in both years was Pontania viminalis (L.). Index of occurrence frequency and Agrell's index of species co-existence have been calculated. This index reached the highest values in case of Pontania dolichura (Thoms.) and P. viminalis (L.) in 1999 as well as Phyllocolpa leucaspis (Tischb.) and P. viminalis (L.) in 2000. 相似文献