全文获取类型
收费全文 | 186篇 |
免费 | 9篇 |
专业分类
林业 | 8篇 |
农学 | 15篇 |
基础科学 | 1篇 |
45篇 | |
综合类 | 11篇 |
农作物 | 34篇 |
水产渔业 | 20篇 |
畜牧兽医 | 41篇 |
园艺 | 2篇 |
植物保护 | 18篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 8篇 |
2004年 | 2篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1978年 | 3篇 |
排序方式: 共有195条查询结果,搜索用时 0 毫秒
71.
Journal of Plant Diseases and Protection - The effect of the bacterial strain Pseudomonas fluorescens 5.014 together with three commercial biocontrol products (Binab T, Gliomix and Mycostop)... 相似文献
72.
The importance of subsoil denitrification on the fate of agriculturally derived nitrate (NO3) leached to groundwater is crucial for budgeting N in an ecosystem and for identifying areas where the risk of excess NO3 is reduced. However, the high atmospheric background of di-nitrogen (N2) causes difficulties in assessing denitrification enzyme activity (DEA) and denitrification potential (DP) in soils directly. Here, we apply Membrane Inlet Mass Spectrometry (MIMS) technique to investigate indirectly DEA and DP in soils by measuring N2/Ar ratio changes in headspace water over soil. Soils were collected from 0-10, 15-25 and 60-70 cm depths of a grazed ryegrass and grass-clover. The samples were amended with helium-flushed deionized water containing ranges of NO3 and carbon (glucose-C) and were incubated for six hours in the dark at 21 °C. The peaks for N2/Ar ratio, declined with increasing soil depth, indicating a reduced substrate requirements to initiate DEA en-masse (15-30 mg NO3-N alone or with 60-120 mg glucose-C, kg−1 soil). The dissolved N2O concentrations were very small (0.004-0.269 μg N kg−1 soil) but responded well to the added N and C, showing a reduction in DEA with soil depth. In three separate studies, only subsoils were incubated for 3 days at 12 °C with 20-30 mg NO3-N ± 40-60 mg glucose-C, kg−1 soil. Denitrification capacity (DC, NO3 only treatment) was not statistically different to the control (no amendment) within a land use (0.03-0.05 vs. 0.07-0.22 mg N kg−1 soil d−1), the highest being in ryegrass subsoils receiving groundwater. The DP was significantly (P < 0.0001) higher in subsoils under ryegrass than under grass-clover (0.50-0.71 vs. 1.15 mg N kg−1 soil d−1). The rates of DP (NO3 + glucose-C) increased significantly (P < 0.0001) in unsaturated and saturated subsoils (0.92 and 2.19 mg N kg−1 soil d−1, respectively) of grass-clover, due to the higher reductive state resulting from the 10 day pre-incubation. Available C accelerated denitrification in soils and superseded the temporary elevation in oxidative state due to NO3 addition. The substrates load differences between the land uses regulated the degree of denitrification rates. Results suggest that both dissolved N2O measured by gas chromatography and N2/Ar ratio measured by MIMS to indirectly determine DEA, and the latter to quantify total DC/DP in soils can be used. However, interference of oxygen in the MIMS system should be considered if available C is added or is naturally elevated in soil or groundwater. 相似文献
73.
TM El‐sherry MA Abdel‐Ghani NS Abou‐Khalil M Elsayed M Abdelgawad 《Reproduction in domestic animals》2017,52(5):781-790
The aim of the present research is to study the effect of pH values on the sperm rheotaxis properties. Semen collected from bulls was diluted with SOF medium (1:10). pH of the medium was adjusted using a digital pH meter to the following pH values: 6.0, 6.2, 6.4, 6.4, 6.8, 7.0. All kinetic parameters of sperm (n = 3,385) were determined through a computer‐assisted sperm analysis (CASA) system using microfluidic devices with controlled flow velocity. The following parameters were determined: total motility (TM%), positive rheotaxis (PR%), straightline velocity (VSL, μm/s), average path velocity (VAP, μm/s), linearity (LIN, as VSL/VCL, %), beat cross‐frequency (BCF, Hz) and curvilinear velocity (VCL, μm/s). Nitric oxide, calcium and potassium were estimated in semen at different pH values. To confirm the effect of nitric oxide and K+, we used sodium nitroprusside (an NO donor) and KCL as (a K+ donor) to see their effect on sperm PR%. The results showed no difference in TM% at pH (6–7). The PR% was the lowest at pH 6 and 7. The best parameters for the PR% were at pH 6.4–6.6. The concentration of Ca+2 did not change at different pH values. The mean NO values decreased with the increase of pH; however, the mean values of K+ increased with the increase of pH. Addition of high concentration of NO and K+ to the semen media at fixed pH level had a negative effect on TM% and PR%. In conclusion, the bull sperm had the best rheotaxis properties at pH 6.4–6.6 and sensitive to the change of seminal NO and K+. 相似文献
74.
In this study, the effect of the methanolic extract of Balanites aegyptiaca fruits (BAE) on adult Toxocara vitulorum was evaluated after incubating the parasites in Ringer solution containing 10, 30, 60, 120 and 240 μg/ml of the methanolic extract, for 24h using light and scanning electron microscopic observations. Differences in response to BAE action were concentration dependent. These changes occurred in definite sequences in response to BAE concentration and were consisted of slightly swelling which became pronounced and so severe, with lips showed wrinkled cuticular surface and deformed sensory papillae on increasing the BAE concentration. The strongest effects were reached with the highest BAE concentration, where disorganization of the cuticle and body musculature was observed. Additionally, the ovicidal effect of BAE, at the previous concentrations, on the development of T. vitulorum eggs was examined after 12h exposure. The inhibitory activity of BAE on egg development was concentration dependent and the highest value reached to 100% with the concentration of 240 μg/ml. These results were compared with those observed in the worm cuticle and eggs following incubation in albendazole, as it was a broad-spectrum nematodicidal compound with well-known ovicidal activity. 相似文献
75.
Partial purification and characterization of a protein in porcine follicular fluid which restricts sperm-egg interaction in vitro. 下载免费PDF全文
An attempt was made to isolate and characterize a component in preovulatory porcine follicular fluid (pFF) which has a restricting effect on sperm-egg interaction in vitro. Using the zona-free hamster ova (eggs) penetration assay as an in vitro test system, it was shown previously that the numbers of porcine spermatozoa attached to or penetrated into each egg and the number of eggs with sperm attached or penetrated decreased significantly as the concentration of pFF was increased in the culture medium. In the present study, the component in pFF having these effects was shown to be a heat stable, nonsteroidal substance which retained its activity after dialysis, lyophilization and gel filtration chromatography. The activity was also found to be present in preovulatory homologous serum. Separation of the material on protein type gel filtration columns with detection at 280 nm, together with the banding seen with Coomassie staining on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), suggests that it is a protein. Based on high pressure liquid chromatographic separation (HPLC) and SDS-PAGE analyses, the bioactivity could be due to a single protein of 87 kD or to one or more of three smaller proteins, possibly disaggregated products of the 87 kD protein, in the range of 26-28 kD. 相似文献
76.
77.
Crossbreeding effects for litter and lactation traits in a Saudi project to develop new lines of rabbits suitable for hot climates 总被引:1,自引:1,他引:0
A.M. Al-Saef M.H. Khalil A.H. Al-Homidan S.N. Al-Dobaib K.A. Al-Sobayil M.L. García M. Baselga 《Livestock Science》2008,118(3):238-246
A five-years crossing scheme involving the Spanish V line (V) and Saudi Gabali (S) rabbits was practiced to produce 14 genetic groups: V, S, 1/2V1/2S, 1/2S1/2V, 3/4V1/4S, 3/4S1/4V, (1/2V1/2S)2, (1/2S1/2V)2, (3/4V1/4S)2, (3/4S1/4V)2, ((3/4V1/4S)2)2, ((3/4S1/4V)2)2, Saudi 2 (a new synthetic line) and Saudi 3 (another new synthetic line). A total of 3496 litters from 1022 dams were used to evaluate litter size at birth (LSB) and weaning (LSW), litter weight at birth (LWB), litter weight at 21 d (LW21) and litter weight at weaning (LWW), pre-weaning litter mortality (PLM), milk yield at lactation intervals of 0–7 d (MY07), 0–21 d (MY021), 0–28 d (TMY) and milk conversion ratio as g of litter gain per g of milk suckled during 21 d of lactation (MCR021). A generalized least squares procedure was used to estimate additive and heterotic effects (direct, maternal, and grand-maternal).The comparison among V, S, Saudi 2 and Saudi 3 showed a complementarity between V and S. Line V was superior for LSB, LSW, LWB, PLM, MY07, MY021 and TMY, while line S was superior for the other traits (LW21, LWW and MCR021). Saudi 2 and Saudi 3 had the means equal to or higher than the founder lines (V or S) for all traits. Saudi 2 showed better values in litter size and pre-weaning litter mortality compared to Saudi 3 with no significant differences for the other traits. Concerning crossbreeding parameters, direct additive effects were significant for all traits, ranging between 12.3% and 31.8% relative to the average of the means of V and S. All estimates for direct heterosis except LWB and MCR021 were significant and ranged from 5.3% to 27.5%. No estimates for maternal additive effects and grand-maternal additive and heterotic effects were significant. Only estimates for maternal heterotic effects of LSB and LSW were significant (8.6% and 10.6%, respectively). 相似文献
78.
Screening techniques and sources of resistance against parasitic weeds in grain legumes 总被引:1,自引:0,他引:1
Diego Rubiales Alejandro Pérez-de-Luque Mónica Fernández-Aparico Josefina C. Sillero Belén Román Mohamed Kharrat Shaban Khalil Daniel M. Joel Charlie Riches 《Euphytica》2006,147(1-2):187-199
Summary A number of parasitic plants have become weeds, posing severe constraints to major crops including grain legumes. Breeding
for resistance is acknowledged as the major component of an integrated control strategy. However, resistance against most
parasitic weeds is difficult to access, scarce, of complex nature and of low heritability, making breeding for resistance
a difficult task. As an exception, resistance against Striga gesnerioides based on a single gene has been identified in cowpea and widely exploited in breeding. In other crops, only moderate to low
levels of incomplete resistance of complex inheritance against Orobanche species has been identified. This has made selection more difficult and has slowed down the breeding process, but the quantitative
resistance resulting from tedious selection procedures has resulted in the release of cultivars with useful levels of incomplete
resistance. Resistance is a multicomponent event, being the result of a battery of escape factors or resistance mechanisms
acting at different levels of the infection process. Understanding these will help to detect existing genetic diversity for
mechanisms that hamper infection. The combination of different resistance mechanisms into a single cultivar will provide durable
resistance in the field. This can be facilitated by the use of in vitro screening methods that allow highly heritable resistance components to be identified, together with adoption of marker-assisted
selection techniques. 相似文献
79.
Physiological and molecular evaluation of ten Egyptian barley cultivars under salt stress conditions
Khalil Shaimaa R. M. Ashoub Ahmed Hussein Basita A. Brüggemann Wolfgang Hussein Ebtissam H. A. Tawfik Mohamed S. 《Journal of Crop Science and Biotechnology》2022,25(1):91-101
Journal of Crop Science and Biotechnology - Ten Egyptian barley cultivars (Giza 129, 132, 123, 127, 2000, 130, 126, 135, 128 and 133) were assessed under 0, 100 and 200 mM NaCl. The... 相似文献
80.
The hydroalcoholic extract (HAE) of the leaves of Dodonaea viscosa, given by oral route at dose of 300 mg/kg, significantly inhibited the paw edema induced by carrageenin injection. The extract did not show any sign of toxicity in mice up to 5000 mg/kg p.o. This result seems to support the use of D. viscosa leaves ethanolic extract in relieving inflammation. 相似文献