全文获取类型
收费全文 | 2008篇 |
免费 | 122篇 |
国内免费 | 10篇 |
专业分类
林业 | 153篇 |
农学 | 118篇 |
基础科学 | 38篇 |
460篇 | |
综合类 | 145篇 |
农作物 | 277篇 |
水产渔业 | 183篇 |
畜牧兽医 | 439篇 |
园艺 | 76篇 |
植物保护 | 251篇 |
出版年
2024年 | 3篇 |
2023年 | 19篇 |
2022年 | 66篇 |
2021年 | 81篇 |
2020年 | 93篇 |
2019年 | 126篇 |
2018年 | 142篇 |
2017年 | 129篇 |
2016年 | 133篇 |
2015年 | 71篇 |
2014年 | 84篇 |
2013年 | 212篇 |
2012年 | 111篇 |
2011年 | 131篇 |
2010年 | 104篇 |
2009年 | 67篇 |
2008年 | 120篇 |
2007年 | 57篇 |
2006年 | 45篇 |
2005年 | 38篇 |
2004年 | 33篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 17篇 |
2000年 | 27篇 |
1999年 | 16篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有2140条查询结果,搜索用时 15 毫秒
31.
Mahmoudreza Ovissipour Abdolmohammad Abedian Kenari Rajabmohammad Nazari Ali Motamedzadegan Barbara Rasco 《Aquaculture Research》2014,45(4):591-601
The effect of fish protein hydrolysate (FPH) on the growth, feed utilization, digestive enzymes, gut microflora and resistance to bacterial challenge in Persian sturgeon (Acipenser persicus) larvae during a 45‐day feeding trial has been investigated. Artificial diets containing different levels of tuna visceral protein hydrolysate (PH0, PH10, PH25 and PH50) and live foods (Artemia: 5 days, Daphnia: 40 days) were fed to Persian sturgeon larvae. Larvae fed on the PH10 and PH25 had growth, feed utilization, protein content and trypsin activity significantly better than PH0 and PH50 groups (P < 0.05). Condition factors, survival rate and pepsin activity were not significantly different (P > 0.05). Brush border membrane enzymes to cytosolic enzyme ratio revealed that maturation had been occurred in 41 days post hatch (dph) at moderate FPH levels. In 54 dph larvae, this ratio was not affected by the level of FPH in the diet. No significant differences were observed in the total number of gut microflora or in the resistance to Aeromonas hydrophila (P > 0.05), whereas lactic acid bacteria was significantly higher in PH50 (P < 0.05). The results of this study show that application of moderate levels of FPH in Persian sturgeon diets could enhance larvae performance due to the early maturation in intestinal. 相似文献
32.
Effects of the prebiotic mannan‐oligosaccharide on feed deprived zebrafish: Growth and reproduction
下载免费PDF全文
![点击此处可从《Aquaculture Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mohammad Navid Forsatkar Mohammad Ali Nematollahi Gholamreza Rafiee Hamid Farahmand Christian Lawrence 《Aquaculture Research》2018,49(8):2822-2832
This study was designed to investigate whether the prebiotic mannan‐oligosaccharides (MOS) can reduce the deleterious impacts of feed deprivation on growth and reproduction in zebrafish. In the growth performance experiment, juvenile fish were distributed in the following four treatments: normal‐control (NC), starved‐control (SC), normal‐prebiotic (NP) and starved‐prebiotic (SP). After 8 weeks, NP and SC fish showed the highest and lowest growth patterns, respectively among treatments. Standard length, specific growth rate and feed conversion ratio did not differ significantly between NC and SP treatments. Autochthonous lactic acid bacteria (LAB) were significantly higher in NP and SP than the NC and SP treatments. Feed restriction resulted in significantly lower concentrations of thyroxine. In the reproductive performance experiment, additional juveniles were fed as in the growth experiment. Crossing in the final week of the experiment resulted in successful spawning in only NP fish, which showed mature sperm and oocytes in histological examinations. The number of spermatozoa was significantly lower in the fish that experienced feed restriction; however, the oocytes of SP females were at the same maturation level to that observed in NC females. Sex‐steroids changed after both starvation and MOS supplementation where NC and SP showed no differences in the levels of testosterone and female's 17β‐estradiol. These results indicate that MOS supplemented diet reduced some side effects of feed deprivation (final weight and length, SGR, FCR and levels of LAB and T3), and suggest that supplementation of the diet with MOS may ameliorate some of the negative effects of feed deprivation in zebrafish. 相似文献
33.
Khemiss F Ahmadi S Massoudi R Ghoul-Mazgar S Safta S Moshtaghie AA Saïdane D 《Fish physiology and biochemistry》2009,35(3):541-549
The everted gut sac technique has been used to investigate the effect of Vibrio vulnificus on water and electrolyte (Na+, K+, Cl−, HCO3
−) transport on the intestine of sea bream (Sparus aurata L.). Both the anterior and the posterior intestine were incubated in a medium containing 108
V. vulnificus cells ml−1 at 25°C for 2 h. The presence of V. vulnificus resulted in a significant reduction (P < 0.05) of water absorption in the anterior intestine, while sodium absorption in the anterior (P < 0.01) and posterior (P < 0.05) intestine was elevated. Chloride absorption was increased, but the changed was not significant, while potassium absorption
decreased significantly (P < 0.05), but only in the posterior intestine. Incubation the sea bream intestine with V. vulnificus did not affect carbonate secretion in the anterior segment, whereas high secretion was stimulated in the posterior segment
(P < 0.01). Histological evaluations demonstrated damage in the anterior intestine of sea bream that was characterized by the
detachment of degenerative enterocytes, alterations in the microvilli, and the presence of a heterogenous cell population,
indicating inflammation. Based on our results, we conclude that V. vulnificus caused cell damage to the intestine of sea bream and that the anterior intestine is more susceptible than the posterior part
of the intestine. Several hypotheses are suggested to explain our observations, such as the presence of higher numbers of
villosities in the anterior intestine than in the posterior one and/or the presence of endogenous bacteria in the posterior
intestine which may have a protector role. 相似文献
34.
Cryopreservation of Persian sturgeon (Acipenser persicus) sperm: effects of cryoprotectants,antioxidant, membrane stabilizer,equilibration time and dilution ratio on sperm motility and fertility
下载免费PDF全文
![点击此处可从《Aquaculture Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Three experiments were performed to develop protocols for cryopreservation of Persian sturgeon Acipenser persicus, sperm. In the first experiment, sperm from six males was individually split in three subsamples and cryopreserved using Modified Tsvetkova's extender (mT) supplemented with dimethyl sulfoxide (DMSO), methanol (MeOH), glycerol (Gly) and ethylene glycol (EG) at concentration of 5%, 10%, 15% and 20%. In the second set of experiments, the effects of six equilibration times (0, 5, 10, 20, 40 and 60 min) and dilution ratios (volume sperm: volume extender 1:0.5, 1:1, 1:2, 1:3, 1:5 and 1:10) and the additive advantage of bovine serum albumin (BSA; 0, 2.5, 5 and 10 mg mL?1) and ascorbic acid (0, 2.5, 5 and 10 U mL?1), on the post‐thaw survival of sperm (triplicate set of six fish) were evaluated. Then, sperm was diluted in 1:1 mT extender with 10 mg mL?1 BSA with selected cryoprotectants (15% MeOH and 10% DMSO) for 5 min. After a month of storage in liquid nitrogen, post‐thawed sperm motility; fertilization and hatching rate and viability of derived larvae were measured (Exp.3). Evaluation of cryoprotectants efficiency showed that MeOH 15% and DMSO 10% were suitable for cryopreservation of Persian sturgeon sperm. Gly and EG resulted in very low post‐thaw motility rates even at lowest concentration. No significant difference was observed among the four different equilibration times (0, 5, 10, 20 min) (P > 0.05) although higher equilibration times than 20 min resulted low post‐thaw motility (P < 0.05). The motility of frozen–thawed sperm did not significantly change when dilution ratio was increased from 1:0.5 to 1:3 (P > 0.05). However, higher dilution ratios (1:5 and 1:10) reduced the percentage of motile sperm. Supplementation of the cryoprotectant solution with 10 mg mL?1 BSA significantly improved post‐thaw motility (P < 0.05), but ascorbic acid did not improve post‐thaw motility (P > 0.05). The results of experiment 3 showed that the highest fertilization (30.2 ± 5.75) and hatching rates (28.2 ± 5.25) were observed when samples were frozen with 15% MeOH (P > 0.05). Our study indicates that the use of mT extender consisting of 10 mg mL?1 BSA in 15% MeOH diluted with sperm at 1:1 ratio for 5 min can be recommended cryopreservation method for Persian sturgeon sperm. 相似文献
35.
辣椒(Capsicum spp.)原产于中南美洲,大约450~500年前,由葡萄牙商人引入印度,并很快在印度大量栽培,成为印度的重要经济作物。2003年印度辣椒种植面积94.55万hm^2,年产鲜椒450万t。印度是辣椒生产大国,也是世界上种植pimento红辣椒最大的国家,面积和产量分别占全球市场份额的46%和44%,单产4.7t/hm^2,低于中围(25.6/hm^2)、 相似文献
36.
Maryam Yadegari Mahmoud Orazizadeh Mahmoud Hashemitabar Ali Khodadadi 《Iranian Biomedical Journal》2013,17(4):187-193
Background: Previous studies have shown that some cytokines have protective effects on cartilage in joint diseases. In the current study, effects of IL-4 against morphological changes and tissue degradation induced by IL-1α on bovine nasal cartilage (BNC) explants were investigated. Methods: Fresh BNC samples were prepared from a slaughterhouse under sterile conditions. BNC explants culture was treated with both IL-lα (10 ng/ml) and IL-4 (50 ng/ml) at the same time for 28 days. The morphological characteristics of explants were assessed by using histology techniques and invert microscopy. Matrix metalloproteinase-1 (MMP-1) production was assessed within different days by using Western blotting. Results: IL-lα induced prominent cartilage morphology degradation. The pro and active form of MMP-1 band substantially increased at day 21 of culture. In the presence of both IL-lα and IL-4, chondrocytes preserved their ordinary normal phenotype with intact extracellular matrix. In addition, a significant reduction in pro-MMP-1and inhibition of active MMP-1 was seen. Conclusion: In conclusion, IL-4 could be regarded as a potential candidate in cartilage protecting against the degradation changes of IL-lα. It seems that the preservation effect of IL-4 is associated with significant reduction of MMP-1. Key Words: Chondrocyte, Interleukin-1α, Interleukin-4, Matrix metalloproteinase-1, Bovine nasal cartilage 相似文献
37.
Fazli Wahid Muhammad Sharif Muhammad Adnan Imtiaz Ali Khan Emre Aksoy 《Journal of plant nutrition》2013,36(15):1760-1769
AbstractInoculation effect of arbuscular mycorrhizal fungi (AMF) on phosphorus (P) transfer from composted dung of cattle with a diet supplemented with powdered rock phosphate (RP) and their successive uptake by mung bean plants was assessed in alkaline soil. The efficacy of composted RP fed dung alone or/and in combination with AMF inoculums containing six different species were compared with SSP in six replicates per treatment in pots. The results showed that the association of AMF with composted RP fed dung had a positive effect on mung bean shoot (3.04?g) and root (2.62?g) biomass, chlorophyll (a, b), carotenoid contents and N (58.38?mg plant?1) and P (4.61?mg plant?1) uptake. Similarly, the percent roots colonization (56%) and nodulation of mung bean plant roots and their post-harvest soil properties were also improved by the inoculation of AMF together with composted RP fed dung. It is concluded that the combined application of AMF with composted RP fed dung has almost the same effect as SSP for improving mung bean plants growth and their nutrients uptake. Moreover, AMF inoculants can be used as a suitable biofertilizer in combination with locally available organic sources of fertilizers for improving P status and growth of plants in alkaline soils. 相似文献
38.
Critical concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and manganese (Mn) with respect to dry matter yield end antagonistic and synergistic relationships among these nutrients were studied in which tomato (Lycopersicon esculentum L.) was grown in recirculating nutrient solution (NFT). Increments of nutrient elements in the nutrient solution increased the proportional rate of the corresponding nutrient elements. Increasing levels of N negatively correlated with plant P and positively correlated with Ca, Fe, and Zn. Iron and Mn contents of the plants were increased and N, K, Ca, and Mg were decreased as a function of P applied. Increases in K in the nutrient solution caused increases in the concentrations of K, N, P, and Zn, and decreases in the concentration of Ca and Fe. Applied Ca increased the concentrations of Ca and N, and decreased the concentrations of P, Mg, Fe, Zn, and Mn. Potassium, Ca, and Fe contents of the plants were decreased and Zn increased, while N, P, and Mn were not affected by the increasing levels of external Mg. Iron suppressed the plant Mg, Zn, and Mn contents. Synergism between Zn and Fe was seen, while P, K, Ca, Mg, and Mn contents were not affected by Zn levels. Potassium, Ca, Mg, and Fe were not responsive to applied Mn, however, N and P contents of the plants were decreased at the highest levels of Mn. 相似文献
39.
Ali vahdati Ebrahim Amiri Ali Akbar Ebadi Ali Faramarzi 《Communications in Soil Science and Plant Analysis》2020,51(16):2137-2146
ABSTRACT The present study was conducted to assess the ability of AquaCrop model in predicting of grain and biological yield of rice genotypes in water management. A two-year field experiment was conducted at the experimental farm of the Iranian Rice Research Institute in Rasht, Iran from 2016 to 2017. The experiment was established in a split-plot design with two irrigation management (continuous submergence and end season water stress) as the main plot, fourth rice genotypes as the sub-plot and three replications. The goodness-of-fit between observed and simulated grain yield and final biomass was assessed by means of the coefficient of determination (R 2), the absolute and normalized root mean square errors (RMSE). The RMSEn of predicting grain yield at calibration and evaluation stages was in the range of 6–12% and 6–8% for biological yield. The results indicated that AquaCrop model is suitable to predict grain yield and biological yield of rice genotypes in northern Iran. AquaCrop model can be used to determine optimization strategies to improve the water consumption of rice genotypes. 相似文献
40.
Irshad Ahmad Bashir Ahmad Shahzad Ali Muhammad Kamran Bayasgalan Bilegjargal 《Journal of plant nutrition》2017,40(15):2109-2115
The objective of this study was to evaluate the effects of organic and inorganic fertilizers on the yield and quality of sugar beet genotypes (Beta vulgaris L.). Therefore, a field trial was carried out in Peshawar, Pakistan, during the winters in 2012–2013. The field experiment was conducted in a randomized complete block design with split plots, having three replications. Fertilizer treatments (control, composted manure Higo Organic Plus at 5 t ha?1, Maxicrop Sea Gold seaweed extract at 5 L ha?1, farm yard manure at 10 t ha?1, inorganic nitrogen–phosphorus (NP) at 90:60 kg ha?1, NP at 120:90 kg ha?1 and NP at 150:120 kg ha?1) were allotted to main plots, while genotypes (Sandrina, Serenada and Kawe Terma) were allotted to the sub-plots. Plots treated with the application of NP at 120:90 kg ha?1 produced the highest beet yield (76.4 t ha?1) and sugar yield (11.1 t ha?1), and had the second highest polarizable sugar content (14.52%) and more economic return (Rs. 553,000 per hectare) as compared to control plots. Sugar beet genotype Serenada had significantly higher beet yield (55.5 t ha?1) and sugar yield (7.9 t ha?1) and a higher economic return (Rs. 380,000 per hectare) than the other genotypes. Sugar beet genotype Serenada supplied with NP at 120:90 kg ha?1is recommended for the general cultivation in the agro-climatic conditions of Peshawar valley. 相似文献