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21.
The translational dynamics of poly(ethylene glycol) (PEG) polymers with molecular weights (Mw) varying from 6x10(2) to 5x10(5) were investigated by pulsed field gradient NMR in casein suspensions and in gels induced by acidification, enzyme action, and a combination of both. For molecules with Mwor=8000, there was strong dependence of diffusion on PEG size and on the casein network structure as revealed by scanning electron microscopy images. The diffusion coefficients of the two largest PEGs were increased after coagulation by amounts that depended on the internal structure of the gel. In addition, the 527,000 g/mol PEG was found to deviate from Gaussian diffusion behavior to greater or lesser extents according to the casein concentration and the sample microstructure. The results are discussed in terms of network rearrangements. 相似文献
22.
I. François F.‐X. Lalèyê M. Micat K. Benredouane K. Portier 《Equine veterinary journal》2014,46(5):596-600
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Guillaume Sallé Carole Moreno Simon Boitard Julien Ruesche Aurélie Tircazes-Secula Frédéric Bouvier Mathias Aletru Jean-Louis Weisbecker Fran?oise Prévot Jean-Paul Bergeaud Cathy Trumel Christelle Grisez Emmanuel Liénard Philippe Jacquiet 《Veterinary research》2014,45(1):68
This study reports a functional characterization of a limited segment (QTL) of sheep chromosome 12 associated with resistance to the abomasal nematode Haemonchus contortus. The first objective was to validate the identified QTL through the comparison of genetically susceptible (N) and resistant (R) sheep produced from Martinik × Romane back-cross sheep. The R and N genotype groups were then experimentally infected with 10 000 H. contortus larvae and measured for FEC (every three days from 18 to 30 days post-challenge), haematocrit, worm burden and fertility. Significant differences in FEC and haematocrit drop were found between R and N sheep. In addition, the female worms recovered from R sheep were less fecund. The second step of the characterization was to investigate functional mechanisms associated with the QTL, thanks to a gene expression analysis performed on the abomasal mucosa and the abomasal lymph node. The gene expression level of a candidate gene lying within the QTL region (PAPP-A2) was measured. In addition, putative interactions between the chromosome segment under study and the top ten differentially expressed genes between resistant MBB and susceptible RMN sheep highlighted in a previous microarray experiment were investigated. We found an induction of Th-2 related cytokine genes expression in the abomasal mucosa of R sheep. Down-regulation of the PAPP-A2 gene expression was observed between naïve and challenged sheep although no differential expression was recorded between challenged R and N sheep. The genotyping of this limited region should contribute to the ability to predict the intrinsic resistance level of sheep. 相似文献
25.
Marie-Laure Desprez-Loustau Gilles Saint-Jean Benoît Barrès Cécile Françoise Dantec Cyril Dutech 《Annals of Forest Science》2014,71(5):563-573
Context
Parasites can induce strong effects on their host’s growth, not only as a result of host resource exploitation (growth loss) but also with a potential adaptive value for host (tolerance response) and themselves (increased transmission).Aims
We assessed these three types of phenotypic changes in oak seedlings infected by powdery mildew.Methods
A manipulative field experiment with three levels of parasite inoculum was designed in order to tease apart infection from genetic effects on oak growth. Seedlings were monitored during 3 years for height growth, phenology and infection.Results
Powdery mildew infection induced both significant growth loss and qualitative changes in plant architecture. The most striking and unexpected change was increased growth polycyclism in infected seedlings. This benefitted both the host as a form of compensation for infection-caused height loss, and the pathogen, by increasing sporulation.Conclusion
The study highlights the effect of parasites in the expression of plant phenotypic traits, such as phenology and ultimately tree architecture. Both host tolerance and parasitic manipulation may be involved in the observed changes in growth patterns. These results suggest a complex interplay between development and defence in trees and emphasize the need to better assess tolerance mechanisms when considering the defence strategies of trees against pathogens. 相似文献26.
D.A.R. Vilela S.G.B. Silva M.T.D. Peixoto H.P. Godinho L.R. França 《Fish physiology and biochemistry》2003,28(1-4):187-190
The morphometric study of spermatogenic cysts in sexually mature tilapias, during the evolution of spermatogenesis, showed a dramatic increase in both number of germ cells and cyst volume. However, the opposite trend was observed for germ cell size. Nevertheless, the number of Sertoli cells increased gradually up to leptotene/zygotene cysts, stabilizing thereafter. Based on the number of spermatids supported by each Sertoli cell and compared to mammals, Sertoli cell efficiency in tilapias is remarkably high. Sertoli cell proliferation was frequently observed, mainly in spermatogonial cysts, and probably is the major factor related to the testis growth and the increase in sperm production that normally occurs in adult tilapias. The combined duration of spermatocytes (5 days) and spermiogenic (5–6 days) phases of spermatogenesis in fish kept at 25 °C was 10–11 days. Mainly due to acceleration in meiosis, these two phases lasted a total of 6 days in tilapias kept at 30 °C, in the opposite way, at 20 °C spermatogenesis was arrested at pachytene spermatocytes. To our knowledge, this is the most comprehensive investigation performed up to date on testis morphometry and function in adult tilapias. 相似文献
27.
Romain Gastineau Fran?ois Turcotte Jean-Bernard Pouvreau Michèle Moran?ais Jo?l Fleurence Eko Windarto Fiddy Semba Prasetiya Sulastri Arsad Pascal Jaouen Mathieu Babin Laurence Coiffard Céline Couteau Jean-Fran?ois Bardeau Boris Jacquette Vincent Leignel Yann Hardivillier Isabelle Marcotte Nathalie Bourgougnon Réjean Tremblay Jean-Sébastien Deschênes Hope Badawy Pamela Pasetto Nikolai Davidovich Gert Hansen Jens Dittmer Jean-Luc Mouget 《Marine drugs》2014,12(6):3161-3189
In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries. 相似文献
28.
Van Campenhout Jean Petit François Peeters Alexandre Houbrechts Geoffrey 《Journal of Soils and Sediments》2022,22(2):704-729
Journal of Soils and Sediments - Suspended sediment transport, which represents the majority of the sediment load, has been studied across very different scales and in a wide variety of regions and... 相似文献
29.
Transposable elements are presents in all known genomes so far, and have the faculty of changing their genomic location and/or number of copies within the genome. They are mobile endogenous genetic elements, with a large variety of structure and transposition mechanism. In crops, they compose the major part of the nucleic DNA, up to 80% in some cereals like maize and wheat. Despite their omnipresence, they are largely unknown and uncharacterized within the Poaceae family. In this review, we describe a possible classification of the elements present in this family, some of their known transposition mechanism, their known activity and possible action in crops, and their possible origin. 相似文献
30.