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181.
To analyze the contribution of neuraminidase (NA) toward protection against avian influenza virus (AIV) infection, three different recombinant Newcastle disease viruses (NDVs) expressing hemagglutinin (HA) or NA, or both, of highly pathogenic avian influenza virus (HPAIV) were generated. The lentogenic NDV Clone 30 was used as backbone for the insertion of HA of HPAIV strain A/chicken/Vietnam/P41/05 (H5N1) and NA of HPAIV strain A/duck/Vietnam/TG24-01/05 (H5N1). The HA was inserted between the genes encoding NDV phosphoprotein (P) and matrixprotein (M), and the NA was inserted between the fusion (F) and hemagglutinin-neuraminidase protein (HN) genes, resulting in NDVH5VmPMN1FHN. Two additional recombinants were constructed carrying the HA gene between the NDV P and M genes (NDVH5VmPM) or the NA between F and HN (NDVN1FHN). All recombinants replicated well and stably expressed the HA gene, the NA gene, or both. Chickens immunized with NDVH5VmPMN1FHN or NDVH5VmPM were protected against two different HPAIV H5N1 and also against HPAIV H5N2. In contrast, immunization of chickens with NDVN1FHN induced NDV- and AIV N1-specific antibodies but did not protect the animals against a lethal dose of HPAIV H5N1. Furthermore, expression of AIV N1, in addition to AIV H5 by NDV, did not increase protection against HPAIV H5N1.  相似文献   
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183.
Translesion synthesis (TLS) is the major pathway by which mammalian cells replicate across DNA lesions. Upon DNA damage, ubiquitination of proliferating cell nuclear antigen (PCNA) induces bypass of the lesion by directing the replication machinery into the TLS pathway. Yet, how this modification is recognized and interpreted in the cell remains unclear. Here we describe the identification of two ubiquitin (Ub)-binding domains (UBM and UBZ), which are evolutionarily conserved in all Y-family TLS polymerases (pols). These domains are required for binding of poleta and poliota to ubiquitin, their accumulation in replication factories, and their interaction with monoubiquitinated PCNA. Moreover, the UBZ domain of poleta is essential to efficiently restore a normal response to ultraviolet irradiation in xeroderma pigmentosum variant (XP-V) fibroblasts. Our results indicate that Ub-binding domains of Y-family polymerases play crucial regulatory roles in TLS.  相似文献   
184.
185.
A theory has been developed for calculating the twist that develops in boards during drying without restraint, as well as the deformation in cross-section that accompanies the development of twist. Calculations require a knowledge of only a limited number of parameters: width, thickness and length of the board, annual ring orientation, distance from the pith, radial, tangential and longitudinal shrinkage coefficients, and the variation of spiral grain angle (SGA) with distance from the pith. The theory is derived from geometrical and physical principles and shows that a complicated interaction between all the above parameters gives rise to twist. A novel coordinate system is used that is better adapted to the fact that spiral grain lies at an angle to the log axis rather than the usual Cartesian or cylindrical polar coordinates. Unlike the finite element models that have recently been developed this theory does not allow for the effect of stresses that develop in a board, although the theory in its present form can easily be extended to incorporate this effect. The advantage of this theory over the more exact finite element models lies in its educational value in that it clearly identifies the mechanisms that are responsible for twist. An associated MS Excel spreadsheet allows rapid analysis of different scenarios such as the effect on twist of changing the shrinkage coefficients, annual ring orientations and moisture content. The theory predicts that for radiata pine 100×50 mm boards maximum twist occurs near the pith, and that the direction of twist reverses when the distance from the pith is greater than about 120 mm. These predictions are shown to agree with experiment. The theory also predicts that if a radiata pine log is live-sawn (through-and-through sawn) there will be two regions in the mature wood where the quartersawn boards will have large negative twist values, but that this can be avoided by cant- or grade-sawing. In contrast, the theory also predicts that if the SGA is constant at 4° from pith to bark, board twist will decrease smoothly from pith to bark for all annual ring orientations without ever becoming negative.  相似文献   
186.
New equipment was developed to measure the strength of individual annual rings in green wood under predominantly tensile stress. This equipment was then used to assess the variation of the radial modulus of rupture (rMOR) in thirty-six 25-year-old radiata pine trees taken from three sites in New Zealand. The rMOR for individual rings ranged from 4.2 to 12.7 MPa and was calculated on the assumption that during bending of the specimens fracture was caused by the tensile force in the radial direction (i.e., perpendicular to the tangential-longitudinal plane). No consistent trends were observed in rMOR from pith to bark; nor was there any evidence of differences between the three sites. However, there was substantial between-tree variability that manifested mainly in different average rMOR values for the trees rather than in variations from pith to bark. These results indicate that there are no concerns with respect to splitting resistance for the juvenile wood of radiata pine. It will be of interest to investigate whether splitting resistance is under genetic control.  相似文献   
187.
The effects of a series of divalent, first row transition elements, i.e. Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ on the crystallization of ferrihydrite have been compared. With the exception of Mn2+, the metal ions considered, stabilized ferrihydrite and enhanced the amount of haematite in the reaction product. The stabilizing ability of these ions could be related to the increase in covalency of these metals along the series. With more than 15 mole% divalent metal ion present, ferrihydrite transformed to a spinel phase by a dissolution/reprecipitation mechanism. These metals can replace some Fe3+ in the structures of the crystallization products. Factors that influence the extent of isomorphous substitution are the match between the radii and charges of Fe3+ and the substituent ions and also, the congruency of dissolution of the M/ferrihydrite coprecipitate.  相似文献   
188.
A modified instantaneous profile method is described, which determines the hydraulic conductivity functions of soils with varying textures. Soil suction head as a function of time and depth, rate of outflow as a function of time and the final distribution of moisture content are monitored on undisturbed soil columns. Data is handled following a modification of the procedure of Weeks and Richards (1967). The apparatus consists of five measuring cells, a monitoring unit, five balances and equipment to section the soil columns for the gravimetric determination of soil moisture content. Each measuring cell contains a soil core of 250 cm3, into which five micro-tensiometers are inserted at 2 cm intervals. Exemplary hydraulic conductivity functions are shown for samples taken from an Arenosol, from silty and clayey-silty horizons of a Luvisol and from a clayey Vertisol. The functions showed good agreement with in situ data. Evaluations of variability show the method to be very reliable. On average, the functions of five samples can be determined in one week, making the method quick. At the same time, the method has great potential for the study of effects of soil structure on hydraulic conductivity.  相似文献   
189.
Summary Land-races are somewhat younger than usually mentioned. Also land-races are not abandoned populations but influenced by a simple continuous, equalizing human selection, as well as by natural evolution. Thus the phenotypical uniformity will be high, while the genetical variability is larger than in commercial bred varieties, but much less than in populations grown in a gene centre. Many effects like resistance, adaptation and continuous annual yield are resulting from the land-race's multiline character, which can be seen as biological model for surviving of agricultural populations. The breeder's effort to isolate certain genes will be troublesome and often less effective because of this multiline symbiosis and genes approaching demand and botanical features of a gone period.
Getreide-Landsorten aus Österreich und ihre Verwendung in der Züchtung
Zusammenfassung Landsorten sind etwas jünger als allgemein angenommen. Landsorten sind auch keine zufälligen Populationen, sondern sie werden sowohl von der ständigen egalisierenden menschlichen Selektion als auch von der natürlichen Evolution beeinflußt. Sie sind deshalb phänotypisch sehr einheitlich. Ihre genetische Variabilität ist zwar höher als bei Zuchtsorten, jedoch nicht so groß wie bei Populationen in einem Genzentrum. Viele Eigenschaften wie Resistenz, Anpassung und kontinuierliche Jahreserträge lassen sich auf den Multilinien-Charakter der Landsorten zurückführen, der wiederum als biologisches Modell für den Fortbestand landwirtschaftlicher Populationen gelten kann. Infolge dieses Multilinien-Charakters der Landsorten ist es für den Züchter schwierig und oft wenig effektiv, bestimmte Gene zu isolieren.

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  相似文献   
190.
Application of no postharvest stress or by size reduction, grinding, chopping, or slicing and exposure to UV light or ultrasound were investigated for the elicitation of trans-resveratrol, total phenolic compounds, and antioxidant activity (AOA) in peanut kernels. AOA and total phenolic compounds did not increase in stressed peanuts over incubation times 0-48 h at 25 degrees C; however, an increase in trans-resveratrol concentration over time occurred. Slicing (2 mm), ultrasound exposure for 4 min at 25 degrees C, and incubation for 36 h produced the highest level of trans-resveratrol synthesis in peanuts, increasing concentrations from 0.48 +/- 0.08 microg/g in untreated peanuts to 3.96 +/- 0.96 microg/g. AOA in stressed peanuts was negatively correlated with trans-resveratrol concentration, indicating that as AOA decreased trans-resveratrol concentration increased.  相似文献   
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