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排序方式: 共有159条查询结果,搜索用时 62 毫秒
51.
Naama Zimerman-Lax Dafna Tamir-Ariel Moshe Shenker Saul Burdman 《Journal of General Plant Pathology》2018,84(1):27-34
The gram-negative bacterium Acidovorax citrulli causes bacterial fruit blotch (BFB) disease of cucurbits, which represents a serious threat to melon and watermelon production worldwide. To date, there are no efficient means to manage the disease, and reliable resistance sources for cucurbit germplasm are lacking. Mineral nutrition markedly affects plant diseases. Recently, we reported that disease severity on melon foliage and A. citrulli growth in the leaf tissue were significantly influenced by the form of nitrogen supply. In the present study, we investigated the influence of potassium nutrition on BFB severity and A. citrulli establishment in the foliage of melon plants. Fertilization with relatively low concentrations of potassium increased these variables compared with higher potassium concentrations. Since establishment of A. citrulli during the growing season is assumed to increase the incidence of fruit infection, the fact that mineral nutrition influences BFB incidence in the plant foliage is of particular importance. 相似文献
52.
Pitch memory: an advantage for the left-handed 总被引:1,自引:0,他引:1
D Deutsch 《Science (New York, N.Y.)》1978,199(4328):559-560
In an auditory or musical task, subjects made pitch recognition judgments when the tones to be compared were separated by a sequence of interpolated tones. The left-handed subjects performed significantly better than the right-handed and also had a significantly higher variance. Further analysis showed that the superior performance was attributable largely to the left-handed subjects with mixed hand preference. 相似文献
53.
Moshe Reuveni Moshe Harpaz Reuven Reuveni 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(9):853-860
Foliar sprays of solutions of di-potassium hydrogen orthophosphate, K2HPO4 (DKP) and potassium di-hydrogen orthophosphate, KH2PO4 (MKP), commercial systemic fungicides, and an alternating treatment with phosphate fertilizer and systemic fungicides inhibited development of the powdery mildew fungus, Oidium mangiferae, on flowers and bloom clusters of field-grown mango trees. The effectiveness of the alternation treatments with an appropriate systemic fungicide and 1% solution of mono-potassium phosphate (MKP) in controlling powdery mildew on bloom clusters was similar to that of the commercial treatment with the systemic fungicides. However, application of the systemic fungicides alone, on the same dates on which they were applied in the alternation treatment, without application of the phosphate treatment was significantly less effective in controlling the disease than either the phosphate or the alternation treatment. This indicates that the use of phosphate fertilizer has a significant role in disease control and that it can reduce the number of fungicide treatments necessary against powdery mildew by up to 50%. These results were confirmed in large-scale demonstration trials conducted in commercial orchards in 1994 and 1995. Our 1997 findings also revealed that tank-mix treatments of 1% MKP solution with half the recommended quantity of sterol inhibitor fungicide applied at 14-day intervals provided a protection against powdery mildew comparable with or superior to that given by the standard fungicides-based treatment applied at 7-day intervals. Tank-mix treatments of MKP (1%) with sterol inhibitor at the recommended rate or with the new strobilurin Kresoxym-methyl (BAS 490F, strobi), or the BAS 490F alone, were the most effective, and provided >95% protection against O. mangiferae, compared with the control. Phosphate solutions were found not to be phytotoxic to plant tissue. These treatments affected the yield of mango trees: a significantly lower yield was observed on control untreated trees, probably because of powdery mildew infection on flowers. The inhibitory effectiveness of phosphate salts makes them a potential major component of an integrated pest management program. 相似文献
54.
55.
Wheat of two strong high-protein and two weak low-protein cultivars from New Zealand and Australia were milled to commercial
specifications. All millstreams were tested for α-amylase, β-amylase, falling number, protein, starch, damaged starch, amylose,
amylopectin, pentosan and ash. The distribution of β-amylase in millstream flours was more variable among cultivars than α-amylase.
Generally, both enzymes had lowest activity in sizing and early reduction flours. α-Amylase was very high in the bran, pollard
and germ fractions, in which ash content was very high, whereas β-amylase was low in these fractions. These observations,
together with the moderate correlation of α-amylase and poor correlation of β-amylase to ash content, suggest that most α-amylasein
flour derives from contamination with bran, pollard and germ, whereas most β-amylase derives from the endosperm. Falling numbers
varied between the cultivars, but variation amongst millstreams for each cultivar was low, except for cv. Frame, which had
particularly high falling number values (834 and 1197) in second and third break flours. These two flours had some of the
highest α-amylase levels and lowest starch levels. However, they also had very high protein content (22 and 26%) and very
low starch damage (3.2 and 4.5%), which may contribute to the high falling numbers. When endogenous α-amylase in the flour
with the highest falling number was supplemented with high levels of barleyα-amylase, the flour withstood the detrimental
effects of α-amylasein baking (sticky crumb, poor crumb texture and loaf volume) better than flours of lower falling number,
but did not withstand the effects ofα-amylase on falling number.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
56.
Evaluation of plant-based water status indicators in mature apple trees under field conditions 总被引:1,自引:0,他引:1
The performance of different indicators of plant water status as a tool for irrigation management was evaluated in mature
field grown ‘Golden Delicious’ apple trees during the late summer of 1998. Control (C) and stress (S) treatments were studied.
In the C treatment trees were irrigated daily at 100% ETc whereas in the S treatment water was withheld during 31 days (DOY’s 236–266). Predawn water potential (Ψpd) and midday stem water potential (Ψstem) were measured several times a week during the experimental period. Three daily measurements of stomatal conductance (gs) and stem water potential were made during five consecutive days in mid-September. Trunk diameter changes (TDC) were recorded
by LVDT sensors, and from these measurements, maximum daily shrinkage (MDS), daily growth (DG), and cumulative growth (CG)
were calculated. Midday Ψstem showed the best ratio between the response to moderate water stress and tree variability (“signal/noise” ratio) among the
indicators studied here, followed closely by Ψpd. On the other hand, the poorest water status indicator was gs. Due to the low trunk growth rate of the trees, and its high variability, DG and CG were not adequate indicators. MDS showed
a lower sensitivity to water stress and a higher variability (CV = 0.19) than midday Ψstem (CV = 0.08) and Ψpd (CV = 0.10). However, MDS correlated well with ET0 and with midday Ψstem (R
2 = 0.79) thus, making this parameter an interesting and promising tool for irrigation management in apple orchards. More research
needs to be done in order to define reference values for MDS and plant water potential indicators, in relation to evaporative
conditions and in different phenological periods, and to quantify the relationship between water status indicators values
and apple tree yield and fruit quality. 相似文献
57.
Precision parameters of methods of analysis required for nutrition labeling. Part I. Major nutrients
W Horwitz R Albert M J Deutsch J N Thompson 《Journal of the Association of Official Analytical Chemists》1990,73(5):661-680
Major components of foods and feeds are fat, protein, and carbohydrates. Fat and protein are determined by direct measurements that are interpreted as the quantity of the constituent. Carbohydrates are usually calculated by difference. For this calculation, values for moisture/solids, ash, and "fiber" are also needed. The readily available collaborative studies for the determination of these major components are reviewed in an attempt to assign precision parameters to validated methods of analysis. When a number of studies for the same analyte, in the same food, by the same method are available, it is seen that the precision parameters among laboratories (standard deviations, SR; relative standard deviations, RSDR) and the ISO maximum tolerable difference functions (repeatability value, r; reproducibility value, R) are not characterized by any conventional distribution. The precision data are best summarized as a median or average parameter and the interval containing the centermost 90% of reported values. Typically, the precision of methods of analysis can be expressed as a function of concentration only, independent of analyte, matrix, and method. The average RSDR value from each collaborative data set can then be used as the numerator in a ratio containing, as the denominator, the value calculated from the Horwitz equation: RSDR = 2 exp (1 - 0.5 log C) where C is the concentration as a decimal fraction. A series of ratios consistently above 1, and especially above 2, probably indicates that a method is unacceptable with respect to precision. By this criterion, only the protein (Kjeldahl) determination is unqualifiedly acceptable with a 90% interval for RSDR of 1 to 3% at C values above about 0.01 (1 g/100 g). Fat, moisture/solids, and ash are acceptable down to limiting concentrations in the region of 1 to 5 g/100 g, if a test portion large enough to provide at least 50 mg of weighable residue or volatiles is specified. Measurements of individual carbohydrates and fiber-related analytes have unexpectedly poor precisions among laboratories. The variability, although high, may still be suitable for nutrition labeling. Reliability of analyses for the control of labeling of the primary nutrients must be achieved through quality assurance programs that require strict adherence to the directions of empirical methods and the use of suitable reference materials for absolute methods. 相似文献
58.
Structural changes in plasma circulating fibrinogen after moderate beer consumption as determined by electrophoresis and spectroscopy 总被引:2,自引:0,他引:2
Gorinstein S Caspi A Goshev I Aksu S Salnikow J Scheler C Delgado-Licon E Rosen A Weisz M Libman I Trakhtenberg S 《Journal of agricultural and food chemistry》2003,51(3):822-827
The effects of short-term moderate beer consumption (MBC) on plasma circulating fibrinogen (PCF) in patients suffering from coronary atherosclerosis were investigated by use of 2-dimensional electrophoresis (2-DE), circular dichroism (CD), and Fourier transform infrared spectroscopy (FT-IR). Forty-eight volunteers after coronary bypass surgery were divided into experimental (EG) and control (CG) groups, each of 24. Patients of the EG group consumed 330 mL of beer/day (about 20 g of alcohol) for 30 consecutive days, and CG volunteers drank mineral water instead of beer. Blood samples were collected before and after the experiment. In 21 out of 24 patients after beer consumption the plasma circulating fibrinogen was compromised: changes in its secondary structure were found. These changes were expressed in relatively low electrophoretic mobility and charge heterogeneity, decrease in alpha-helix and increase in beta-sheet, and in slight shift of amide I and II bands. Our findings indicate that one of the positive benefits of moderate beer consumption is to diminish the production of fibrinogen and its stability, which reduces the potential risk exerted by this protein. Thus, in most of beer-consuming patients some qualitative structural changes in plasma circulating fibrinogen were detected. 相似文献
59.
60.