全文获取类型
收费全文 | 1215篇 |
免费 | 42篇 |
国内免费 | 3篇 |
专业分类
林业 | 92篇 |
农学 | 56篇 |
基础科学 | 16篇 |
217篇 | |
综合类 | 79篇 |
农作物 | 130篇 |
水产渔业 | 131篇 |
畜牧兽医 | 397篇 |
园艺 | 24篇 |
植物保护 | 118篇 |
出版年
2023年 | 14篇 |
2022年 | 46篇 |
2021年 | 55篇 |
2020年 | 71篇 |
2019年 | 60篇 |
2018年 | 46篇 |
2017年 | 49篇 |
2016年 | 46篇 |
2015年 | 50篇 |
2014年 | 50篇 |
2013年 | 101篇 |
2012年 | 78篇 |
2011年 | 93篇 |
2010年 | 43篇 |
2009年 | 24篇 |
2008年 | 53篇 |
2007年 | 49篇 |
2006年 | 29篇 |
2005年 | 26篇 |
2004年 | 32篇 |
2003年 | 27篇 |
2002年 | 23篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1981年 | 6篇 |
1979年 | 5篇 |
1976年 | 4篇 |
1975年 | 7篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1967年 | 2篇 |
1966年 | 3篇 |
排序方式: 共有1260条查询结果,搜索用时 15 毫秒
211.
Waqas Wakil M. Usman Ghazanfar Tahira Riasat Mirza Abdul Qayyum Sohail Ahmed Muhammad Yasin 《Phytoparasitica》2013,41(2):221-234
A local isolate of Metarhizium anisopliae (Hypocreales: Clavicipitaceae), Bacillus thuringiensis subsp. kurstaki and chlorantraniliprole were assessed against six field populations of tomato fruitworm Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) in a series of laboratory bioassays. Two dose rates of B. thuringiensis (0.5, 1 μg g?1), one of both M. anisopliae (1.3?×?106 conidia ml?1) and chlorantraniliprole (0.01 ppm) were applied alone and in combination with each other against 2nd, 3rd, 4th and 5th larval instars. The mortality was observed every 24 h until pupation. The bioassays were carried out at 25°C and 75% r.h. The highest mortality was observed in Rawalpindi with the lowest pupation rate by applying the combined concentrations of B. thuringiensis and chlorantraniliprole. The lowest mortality was observed in population from Gujranwala among all the tested populations. The antagonistic interaction was noted where the high dose rate of B. thuringiensis was combined with M. anisopliae; however, the remaining interactions enhanced the mortality and reduced the percent pupation. The overall results demonstrated that all the treatments gave significant control of the larval instars of H. armigera. The population from Gujranwala proved least susceptible whereas the one from Rawalpindi was highly susceptible. 相似文献
212.
基于主成分分析的云南玉溪市生态安全评价研究 总被引:2,自引:0,他引:2
以云南省为研究对象,采用PSR(压力Press-状态State-响应Response)模型建立玉溪市生态安全评价指标体系,运用主成分分析法对200.5-2009年玉溪市的生态安全现状进行分析和综合评价.结果显示,压力指标呈逐年上升趋势,必须在控制人口数量的前提下,加快城市化进程;状态指标同样呈上升趋势,说明政府对公共设施的投入增加,经济发展和环境保护得到了关注;相应指标也呈上升趋势,说明政府为改善环境作出了努力. 相似文献
213.
A. K. Ahmed G. C. Cresswell A. M. Haigh 《The Journal of Horticultural Science and Biotechnology》2013,88(3):350-354
SummaryOverhead irrigation is a common irrigation practice in nurseries, yet it can be wasteful of water and nutrients. We compared the water use, fertilizer use and growth of ‘Top Gun’ lettuce (Lactuca sativa L.) and ‘Grosse Lisse’ tomato (Lycopersicon esculentum Mill.) seedlings in sub and overhead irrigation systems. Five rates of controlled release fertilizer were used – 0.625, 1.25, 2.5, 5 and 10 kg m–3. Sub-irrigation used 86% less water than overhead irrigation. Irrigation type had a significant effect on some growth measurements by final harvest, 43 d after sowing. The sub-irrigated lettuce seedlings were significantly taller. The overhead irrigated lettuce seedlings had a higher dry weight and more leaves. The sub-irrigated tomato seedlings were taller, had longer leaves, a larger leaf area and more leaves. Increasing levels of controlled release fertilizer produced quadratic type responses over time for shoot dry weight, with 10 kg m–3 producing tomato and lettuce transplants with a higher biomass in a shorter time than lower levels of fertilizer. 相似文献
214.
Ahmed Mohamed Mahdy 《植物养料与土壤学杂志》2012,175(4):560-571
A greenhouse experiment was conducted to investigate the immediate effect of application of mono‐ammonium phosphate (MAP), single superphosphate (SSP), and triple superphosphate (TSP) fertilizers containing varying concentrations of Cd on (1) chemical speciation of Cd and Zn in soil solution by chemical‐equilibrium calculations (MINEQL+4.6 model), (2) growth of barley plants, (3) concentrations of Cd, P, and Zn in soil solution and plant tissue, as well as total plant accumulation of Cd, P, and Zn, and (4) monitoring pH and element changes during incubation periods following phosphate application. Results show that, in general, the pH of soil solution increased during the first 40 d of incubation, then declined. Also, at the end of incubation period, pH of soil solution was affected by fertilization source and fertilization rate. The concentration of Cd in soil solution changed with time. Phosphate fertilization (p < 0.05) or fertilizer source (p < 0.05) showed consistent effects. Also, the application of phosphate fertilizers with three rates significantly increased Zn concentrations in soil solution during the first half (0–30 d) of incubation period and then decreased but still more than in the control. In general, application of different sources of phosphate at 100 g kg–1 did not change the dominant forms of Cd in soil solution during all incubation time intervals. Speciation of Zn in the control after 30 d of incubation had changed, in comparison to 10 d of incubation, and the dominant forms were Zn2+, ZnOH+, ZnHCO3, ZnCO3(aq), and Zn(OH)2(aq). Adding phosphate fertilizer significantly increased both shoot and root dry weight compared to control, indicating P was a growth‐limiting factor in the control plants. The Zn concentrations in shoot and root were lower in the TSP‐ and SSP‐fertilizers treatment than those in the MAP and fertilizer treatments at all rates of fertilization. Adding phosphate increased the Cd : Zn and P : Zn ratios in the shoot and root tissue, with the effect being greater with increasing fertilization rate. Phosphate fertilization greatly increased the total accumulation of Cd of barley compared with the control plants (p < 0.001), with the effect being greater with increasing fertilization rate. Source and rate of fertilizers, and their interactions had significant effect (p < 0.05) on Cd accumulation in the whole plant. 相似文献
215.
Fertigation of humic substances improves yield and quality of broccoli and nutrient retention in a sandy soil 总被引:1,自引:0,他引:1
There is lack of information available concerning the effect of humic substances (HS) applied via fertigation on plant growth in sandy soils. Therefore, a field experiment was carried out at El‐Saff district (20 km southwest of Cairo), Egypt, to investigate the role of HS fertigation on water retention of a sandy soil, yield and quality of broccoli (Broccoli oleracea L.) as well as on soil nutrient concentration retained after harvest. The experiment consisted of six fertigation treatments (50%, 75%, and 100% of the recommended NPK‐fertilizer rate for broccoli combined with and without HS application at 120 L ha–1) in a complete randomized block design with three replicates. Humic substances affected spatial water distribution and improved water retention in the root zone. Furthermore, application of HS increased total marketable yield and head diameter of broccoli as well as quality parameters (i.e., total soluble solids, protein, and vitamin C). Higher nutrient concentrations were found in the broccoli heads and concentrations of plant‐available nutrients in soil after harvesting were also higher, indicating an improvement in soil fertility. In conclusion, HS fertigation can be judged as an interesting option to improve soil water and nutrient status leading to better plant growth. 相似文献
216.
Mallasy LO El Tinay AH Ahmed AR 《Plant foods for human nutrition (Dordrecht, Netherlands)》2002,57(1):63-71
Addition of wheat bran to sorghum flour (Dabar cultivar) at two extraction rates 72% and 80% resulted in lowering reducing sugars. The percent decreasewas 75.6% compared with the control at the end of fermentation period. There was a highly significant (p 0.05) increase in crude fiber content as a result of addition of wheat bran. The increase was from 0.8 to 5.2 and from 0.5 to 5.3% for the 80% S/WB and 72% S/WB blends, respectively. Sorghum bread containing wheat bran was lower in reducing sugars and showed a significant increase (p 0.05) in starch content. Sorghum bread containing wheat bran resulted in a lower in vitro protein and starch digestibilities. 相似文献
217.
Nilima Chaturvedi Md. Jamir Ahmed Nabin Kumar Dhal 《Journal of Soils and Sediments》2014,14(4):721-730
Purpose
Ornamentals can beautify the environment and resolve heavy metal pollution at the same time. Thus, the present study aimed at studying the growth and physiological response of Tagetes patula on iron ore tailings.Materials and methods
Pot-culture experiments were conducted to investigate the effect of iron ore tailings both individually as well as in combination with soil (at different proportions) on the growth, pigment production as well as accumulation and translocation of various heavy metals from the tailings.Results and discussion
The results suggested an increase in growth, chlorophyll content, as well as metal accumulation capacity of T. patula with increasing proportion of tailings in the soil. Furthermore, an increase in antioxidant activities in plants grown on tailings as compared to control was observed which suggests plant efficiency to overcome any stress generated due to excess of heavy metals. The order of accumulation of various heavy metals in the plant parts was observed to be Fe?>?Cr?>?Zn?>?Cu?>?Pb?>?Ni?>?Cd. Both bioaccumulation and translocation values were maximum for Fe and minimum for Ni and Cd, respectively.Conclusions
The overall study clearly suggests plant ability to grow well on the tailings and survive excess of heavy metals present in the tailings. Thus, the plant qualifies well as a potential tool for phytostabilization of iron ore tailings and probably a source of income generation from wasteland owing to its multiple commercial values. 相似文献218.
Mohammed Piro Abdelaziz Benjouad Abdelghafor Karom Ahmed NabichNoureddine Benbihi Khalid El Allali Mohammed Machmoum Lahoussine Ouragh 《Journal of Equine Veterinary Science》2011,31(11):618-624
A total of 17 microsatellite deoxyribonucleic acid loci used routinely for horse parentage control were used to evaluate genetic diversity among normal Arabian horses and severe combined immunodeficiency (SCID) carrier Arabian horses (ArS) and normal Arab-Barb horses and SCID carrier Arab-Barb horses (ArbeS). On the basis of the genotype of 186 horses, mean allelic diversity was estimated as 6.82, 5.53, and 6.7059 in normal Arabian horses, ArS, and for both groups of Arab-Barb horses, respectively. Five specific alleles were observed in ArS and ArbeS, with one common with ArS at HMS6, whereas five alleles common between ArS and ArbeS had a high frequency. Expected and observed heterozygosity showed great heterogeneity in the population studied and were similar or higher when compared with other studies on Arabian horses. Coefficient of gene differentiation Gst of Nei associated with Nei’s genetic distance and multivariate correspondence analysis indicated a possible differentiation between the studied populations when analyzed separately according to breed. Probability of assignment of a horse to a specific group was assessed using a full and partial Bayesian approach. In all, 80.6% of Arab horses and 78.2% of Arab-Barb horses were assigned properly with a partial Bayesian test, which provided better results than the full one. These findings will be useful for identification of SCID carrier horses by using the microsatellite deoxyribonucleic acid loci used routinely for horse parentage control in our laboratory. 相似文献
219.
Tian L Wang H Abdallah AM Prinyawiwatkul W Xu Z 《Journal of agricultural and food chemistry》2011,59(12):6453-6458
The capabilities of two red (RW) and two white wines (WW) in inhibiting cholesterol oxidation were evaluated using a cholesterol emulsion (CE) system. Each RW or WW was mixed with CE at different (v/v) ratios. Cholesterol oxidation was accelerated by a free radical generator, 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH), at 37 °C. The major oxidation product, 7-ketocholesterol, was monitored to determine cholesterol stability in the CE system. At a ratio of 1:250 (RW/CE), 7-ketocholesterol production was not detected during 72 h of oxidation. At a 1:1000 ratio, the inhibition rate of each RW was maintained at 100% at 24 h but decreased afterward. Both WWs had 100% inhibition rate within 48 h at a ratio of 1:10. Also, the capabilities of catechin and resveratrol solutions (1 mg/mL) in inhibiting cholesterol oxidation were studied. Each of the wine polyphenolics showed a 100% of 7-ketocholesterol inhibition rate in 24 h at a ratio of 1:500 (solution/CE). However, the inhibition rate of resveratrol was lower than that of catechin at 48 or 72 h. The results demonstrated that red wine possesses great anti-cholesterol-oxidation capability, which may contribute to health benefits in preventing cardiovascular diseases. Catechin may play a more important role than resveratrol in inhibiting cholesterol oxidation. 相似文献
220.