全文获取类型
收费全文 | 801篇 |
免费 | 46篇 |
国内免费 | 2篇 |
专业分类
林业 | 48篇 |
农学 | 66篇 |
基础科学 | 10篇 |
169篇 | |
综合类 | 32篇 |
农作物 | 73篇 |
水产渔业 | 56篇 |
畜牧兽医 | 303篇 |
园艺 | 17篇 |
植物保护 | 75篇 |
出版年
2024年 | 7篇 |
2023年 | 9篇 |
2022年 | 16篇 |
2021年 | 29篇 |
2020年 | 47篇 |
2019年 | 48篇 |
2018年 | 42篇 |
2017年 | 36篇 |
2016年 | 35篇 |
2015年 | 20篇 |
2014年 | 27篇 |
2013年 | 61篇 |
2012年 | 48篇 |
2011年 | 47篇 |
2010年 | 31篇 |
2009年 | 21篇 |
2008年 | 30篇 |
2007年 | 25篇 |
2006年 | 26篇 |
2005年 | 25篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 15篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 11篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有849条查询结果,搜索用时 15 毫秒
111.
Metwally Abd El-Alim A. Safina Sayed A. Abdel-Wahab Eman I. Abdel-Wahab Sherif I. Abdel-Wahab Tamer I. 《Journal of Crop Science and Biotechnology》2021,24(2):203-220
Journal of Crop Science and Biotechnology - Cropping systems are relatively more important for testing soybean genotypes under Egyptian conditions. A field experiment was carried out at the... 相似文献
112.
A. E. Ismail 《Anzeiger für Sch?dlingskunde》1998,71(7):138-141
Four hardwood barks (HWB) i. e.Acacia arabica (AA),Ficus sycomorus (FS),Morus alba (MA) andZiziphus spinachristi (ZS) were tried as soil amendments at 0.5, 1.0 and 1.5% rates w/w for control ofRotylenchulus reniformis and improvement of cv. Giza 1 sunflower growth under greenhouse conditions. All HWB with various concentrations significantly
(P≤0.01) reduced numbers of larvae in soil, both females and eggmasses on roots, total final nematode population as well as
the nematode build-up as compared to control. 1.5% rate of ZS, AA and MA barks were most effective in reducing numbers of
larvae in soil, total final nematode population and the nematode build-up. Also, 1.5% rate of each of FS and AA barks were
most effective in reducing numbers of females or eggmasses, respectively. On the other hand, the least reduction in the previous
nematode stages and rate of build-up was observed with 0.5% dose of FS bark. Shoot weights were increased significantly with
both of 1.0% and 1.5% doses of each of FS and ZS barks and only with 1.5% dose of MA bark. Both shoot lengths and root weights
increased significantly with 1.5% dose of all HWB or with 1.0% dose of each of AA and ZS barks as compared to control. No
significant increase in root lengths was observed. Generally, there were positive significant correlations between doses of
HWB, each of the reductions in the previous nematode stages and increases in sunflower growth criteria. 相似文献
113.
114.
Regmi NL Abd El-Aty AM Kuroha M Nakamura M Shimoda M 《Journal of veterinary pharmacology and therapeutics》2005,28(6):553-557
We examined inhibitory effects of ofloxacin (OFX), orbifloxacin (OBFX), ciprofloxacin (CFX), enrofloxacin (EFX) and norfloxacin (NFX) on cytochrome P-450 1A (CYP1A) activities using hepatic microsomes from four beagle dogs. Ethoxyresorufin O-de-ethylation was referred as CYP1A activities. All the fluoroquinolones inhibited the reaction in a noncompetitive manner. The determined inhibitory constants were the followings; 10.1 +/- 3.8 mM for OFX, 6.43 +/- 2.01 mM for OBFX, 0.726 +/- 0.134 mM for CFX, 4.06 +/- 1.19 mM for EFX and 4.75 +/- 1.63 mM for NFX respectively. As these values are >100-fold of plasma concentrations after a clinical single dose of the fluoroquinolones, it is suggested that the inhibitory effect on CYP1A activities is not so high to elicit drug-drug interaction with CYP1A substrates, when these fluoroquinolones are co-administered. Mechanism based inhibition was also examined in this study. Of the five fluoroquinolones examined, OFX, OBFX and CFX had this inhibition manner. As this inhibition is irreversible, inhibitory effects of the three fluoroquinolones may accumulate, when they are repeatedly administered. Therefore, OFX, OBFX and CFX may result in substantial drug-drug interaction with a CYP1A substrate even in clinical states. As EFX is metabolized to CFX in the body, it may also have the same possibility. 相似文献
115.
A field calibration experiment was carried out on salt‐affected clayey soil in Syria, to compare the sensitivity to soil electrical conductivity (ECe), and bulk density (ρb) of two instruments for estimating soil moisture: the neutron probe (NP) and the Diviner 2000 capacitance probe (CP). The results showed that the values of the correlation coefficient of the calibration were decreased when the ECe and ρb values increased; this decrease was more pronounced for the Diviner 2000, indicating that it was more sensitive to ρb and ECe than the NP. When only scaled frequency was used in the fitted equation, the Diviner 2000 in wet soil underestimated soil water content significantly at all depths, but especially in the top layer, by up to 0.09 cm3/cm3 compared with gravimetric determinations. However, in dry soil, the Diviner 2000 overestimated the volumetric water content by up to 0.05 cm3/cm3 in the top 15 cm, and by 0.03 cm3/cm3 at 30‐45 cm depth. The performance of the neutron probe was better overall; using a factory calibration curve no significant differences were observed between NP estimates and the gravimetric values. Including both ρb and ECe in the calibration equations improved the fits, although the regression coefficient (R2) for the Diviner 2000 remained low. 相似文献
116.
Taia A. Abd El–Mageed Ahmed M.A. El-Sherif Mahmoud M. Ali Mohamed H. Abd El-Wahed 《Archives of Agronomy and Soil Science》2017,63(6):827-840
A 2-year field experiment (2013 and 2014) was conducted in calcareous soil (CaCO3 19.2%), on soybean grown under three irrigation regimes 100%, 85% and 70% of crop evapotranspiration combined with three potassium (K2O) levels (90, 120 and 150 kg ha?1). The objective was to investigate the complementary properties of potassium fertilizer in improving soybean physiological response under water deficit. Plant water status (relative water content RWC, chlorophyll fluorescence Fv/F0 and Fv/Fm), had been significantly affected by irrigation or/and potassium application. Potassium improved growth characteristics (i.e. shoot length, number, leaf area and dry weight of leaves) as well as physiochemical attributes (total soluble sugars, free proline and contents of N, P, K, Ca and Na). Yield and yield water use efficiency (Y-WUE) were significantly affected by irrigation and potassium treatments. Results indicated that potassium application of 150 and 120 kg ha?1 significantly increased seed yield by 29.6% and 13.89%, respectively, compared with 90 kg ha?1 as average for two seasons. It was concluded that application of higher levels of potassium fertilizer in arid environment improves plant water status as well as growth and yield of soybean under water stress. 相似文献
117.
H. Yasuda S. N. Panda Mohamed A. M. Abd Elbasit T. Kawai T. Elgamri A. A. Fenta H. Nawata 《Paddy and Water Environment》2018,16(4):805-821
We investigated teleconnections of rainfall time series in the central Nile Basin (Sudan and South Sudan) with localities in the global sea surface temperature (SST) field, using monthly rainfall data from 11 gauging stations from 1960 to 1999. Annual rainfall ranged from 100 mm in the north to more than 700 mm in the south, and all stations had a strong contrast between rainy and dry seasons with rainless dry periods of several months. Rainfall time series at the stations were categorized as strongly seasonal, with precipitation concentration index exceeding 16 and seasonality index exceeding 0.9. The rainfall stations were classified into four zones on the basis of annual rainfall, seasonality, and cross-correlations among the stations. We calculated cross-correlations of interannual rainfall time series in summer (July and August) with the global SST field. For short lag times (0 or 1 month), summer rainfall in Zones I and II (northern arid regions) had significant correlations with SST over the eastern Mediterranean Sea and southern Indian Ocean, summer rainfall in Zone III (semiarid region) had significant negative correlations with SST over the Indian Ocean, and summer rainfall in Zone IV (southern wet region) had significant correlations with SST over tropical areas and the southwestern Pacific Ocean. For long lag times (3–6 months), Nile Basin summer rainfall time series had significant correlations with SST in various regions of the Atlantic and Indian Oceans but not the Pacific Ocean. Rainfall in Zones I and II had positive correlations (significance level?<?0.01) with SST south of Greenland and around the Azores Islands and negative correlations with SST south of Madagascar; rainfall in Zone III had negative correlations with SST in parts of the Indian Ocean; and rainfall in Zone IV had significant positive correlations with SST southwest of South Africa and negative correlations with SST in the southwestern Indian Ocean. In sum, rainfall in three of the zones (I, II, and IV) had significant positive and negative correlations with SST in parts of the Indian and Atlantic Oceans. For each of these zones, one positive correlation and one negative correlation were selected and correlations with the time series of the difference between the two SST records were calculated. Correlations of Nile Basin rainfall with the SST differences were stronger than the original positive and negative correlations. The resulting time series of SST difference were applied to an artificial neural network to predict summer rainfall, yielding satisfactory correlation coefficients between the observed and predicted summer rainfall (r?>?0.70). 相似文献
118.
Prevalence of serotypes G6 and G10 group A rotaviruses in dairy calves in Quebec. 总被引:6,自引:0,他引:6 下载免费PDF全文
A H Hussein E Cornaglia M S Saber Y el-Azhary 《Canadian journal of veterinary research》1995,59(3):235-237
Fecal samples from diarrheic and nondiarrheic dairy calves (1 to 3 weeks old) from 12 regions of Quebec, collected between 1992 and 1994, were screened for group A bovine rotavirus (BRV) using a combination of 2 VP6-specific monoclonal antibodies (MAbs) in an enzyme-linked immunosorbent assay (ELISA). The overall prevalence of BRV infection was 26.4% (107/405). In diarrheic calves, BRV infection reached 74.3% (55/74), but only 15.7% (52/331) in nondiarrheic calves. BRV-positive samples were serotyped by enzyme-linked immunosorbent assay (ELISA) using G6 and G10 specific MAbs. The analysis of 107 field samples revealed that, in diarrheic calves, 34.5% (19/55) were G6, 27.2% (15/55) were G10, 9% (5/55) were G6 and G10 positive, and 29.9% (16/55) were G6 and G10 negative. In nondiarrheic calves, 19.2% (10/52) were G6, 19.2% (10/52) were G10, 7.6% (4/52) were G6 and G10 positive, and 53.6% (28/52) were G6 and G10 negative. Rotavirus dsRNA was extracted from BRV-positive samples and examined by polyacrilamide gel electrophoresis (PAGE). Of 107 samples tested, 74 (69.1%) were positive, and all the samples demonstrated a typical group A rotavirus migration pattern. 相似文献
119.
Sameh A. Abdelnour Mohamed E. Abd El‐Hack Mahmoud Alagawany Mayada R. Farag Shaaban S. Elnesr 《Journal of animal physiology and animal nutrition》2019,103(2):477-484
Bee pollen (BP) is one of the most useful therapeutic products favoured by natural medicine scientists because of its possible nutritional and medical applications. It exhibits many impacts such as antimicrobial, immunostimulating, antioxidants and hepatoprotective. Furthermore, BP has some useful therapeutic features in numerous pathological situations such as its impact to normalize wound healing. Based on previous literatures, the level of BP supplement in livestock and poultry ranged from 0.1 to 20 g/kg diet. This variation depends on the species, physiological status, age and purpose of addition; so far generally, it accepted to use the level with no side effects. It has been observed that BP enhanced growth performance, immunity responses and blood variables and had hypoglycaemic activity by reducing the lipid in the blood and carcass. Also, BP contains more nutrients, which stimulate faster differentiation and proliferation of the cells of immune system of birds. Therefore, the present review recommends that BP supplementation (up to 20 g/kg diet) had possible beneficial impacts, antioxidants and protective activities on most of the production, productive and health patterns of livestock. 相似文献
120.