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1.
P. J. Skuce C. F. Johnston I. Fairweather D. W. Halton C. Shaw K. D. Buchanan 《Cell and tissue research》1990,261(3):573-581
Summary The presence and distribution of neuropeptides belonging to the pancreatic polypeptide family have been demonstrated by an indirect immunofluorescence technique in the nervous systems of adult male and female Schistosoma mansoni. Seven antisera of differing regional specificity to pancreatic polypeptide (PP), peptide YY (PYY) and neuropeptide Y (NPY) were employed on both whole-mount and cryostat-sectioned material. Positive immunoreactivity (IR) was obtained with all antisera except an N-terminally-directed antiserum to NPY. In the CNS, immunoreactivity was restricted to cell bodies and nerve fibres in the anterior ganglia, central commissure and dorsal and ventral nerve cords of both sexes, whereas, in the PNS, positive-IR was present in the plexuses innervating the subtegumental musculature and the oral and ventral suckers. Intense immunoreactivity was observed in a plexus of nerve fibres and cell bodies in the lining of the gynaecophoric canal and in fine nerve fibres innervating the dorsal tubercles of the male. In contrast, in the female, strong immunoreactivity was evident in nerve plexuses innervating the lining of the ovovitelline duct and in the wall of the ootype, but most notably in a cluster of cells in the region of Mehlis' gland. Results suggest that molecules with C-terminal homology to the PP-family are present in S. mansoni. These peptides would appear to be important regulatory molecules in the parasite's nervous system and may play a role in the control of egg production. 相似文献
2.
Nutrient transfer between the root zones of soybean and maize plants connected by a common mycorrhizal mycelium 总被引:8,自引:0,他引:8
Gabor J. Bethlenfalvay Maria G. Reyes-Solis Susan B. Camel Ronald Ferrera-Cerrato 《Physiologia plantarum》1991,82(3):423-432
The objective of the study was to determine whether nutrient fluxes mediated by hyphae of vesicular-arbuscular mycorrhizal (VAM) fungi between the root zones of grass and legume plants differ with the legume's mode of N nutrition. The plants, nodulating or nonnodulating isolines of soybean [ Glycine max (L.) Merr.], were grown in association with a dwarf maize ( Zea mays L.) cultivar in containers which interposed a 6-cm-wide root-free soil bridge between legume and grass container compartments. The bridge was delimited by screens (44 μm) which permitted the passage of hyphae, but not of roots and minimized non VAM interactions between the plants. All plants were colonized by the VAM fungus Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe. The effects of N input to N-sufficient soybean plants through N2 -fixation or N-fertilization on associated maize-plant growth and nutrition were compared to those of an N-deficient (nonnodulating, unfertilized) soybean control. Maize, when associated with the N-fertilized soybean, increased 19% in biomass, 67% in N content and 77% in leaf N concentration relative to the maize plants of the N-deficient association. When maize was grown with nodulated soybean, maize N content increased by 22%, biomass did not change, but P content declined by 16%. Spore production by the VAM fungus was greatest in the soils of both plants of the N-fertilized treatment. The patterns of N and P distribution, as well as those of the other essential elements, indicated that association with the N-fertilized soybean plants was more advantageous to maize than was association with the N2 -fixing ones. 相似文献
3.
and
1988. Homosexual male pairing in Schistosoma mansoni.International Journal for Parasitology 18: 1115–1117. To see whether male worms within the gynecophoral canal of another male worm would become feminized (i.e. express vestigial female-associated genes), we established homosexual pairs by twice exposing mice to male cercariae with a 4 or 6-week interval, and perfusing 3–5 weeks later. From 13 to 34% of these worms were found in pairs, compared with 0 to 7% in singly exposed controls. ‘Inner’ males in homosexual pairs showed no histological evidence of female reproductive structures, but were stunted, had poorly developed testes, and the high nuclear density characteristic of mature females. More vitelline follicles occurred in unpaired unisexual males than in homosexually paired males, fewest in bisexually paired males. Uptake of tyrosine, an indicator of vitelline development, occurred in the same relative order. The gynecophoral microenvironment often led to stunting, probably through starvation induced by the relative inaccessibility of host blood to homosexually clasped males. 相似文献
4.
In areas with short growing seasons, poor early vegetative growth of soybean (Glycine max [L.] Merr.) is often attributed to the restrictive effect of cool soil conditions on nodulation and N2-fixation by this subtropical grain legume. However, there are few studies regarding potential genetic variability of soybean and Bradyrhizobium japonicum genotypes for nodulation at cool root-zone temperatures (RZT). Experiments were conducted to (1) test for a threshold temperature for low RZT inhibition of soybean nodulation and (2) ascertain whether this threshold temperature response depends mainly on the micro- or macrosymbiont. In experiment 1 soybean seedlings (Glycine max [L.] Merr. cv. Maple Arrow) were inoculated with 1 ml of a log phase culture of B. japonicum strain 532C, H8 or H15 (the latter two strains were isolated from cold soils of Hokkaido, northern Japan) and maintained at either 16, 17.5, 19 or 25°C RZT. In experiment 2 seedlings of cv. Maple Arrow and a cold-tolerant Evans isoline were combined with strain 532C and two Hokkaido strains (H5, H30) at both 19 and 25°C RZT. Results indicated that N2-fixation at 44 days after inoculation was substantially reduced (30–40%) by RZT as high as 19°C, due to development of less nodule mass and to a delay in the onset of N2-fixation and a small decrease in the number of nodules formed. However, the number of nodules formed was sharply reduced and the time required for the first appearance of nodules was significantly delayed below an RZT of 17.5°C. Differences between cultivars for nodulation and N accumulation were apparent at 25°C, but were abolished by growth at 19°C, indicating that, in spite of differences in growth potential between the cultivars under optimum RZT, both cultivars were equally limited by low RZT. Differences between B. japonicum strains were consistent across temperatures and were largely attributable to higher rates of specific nodule activity recorded for strain 532C, which seemed well adapted to low RZT. These results suggest that the host plant mediates the sensitivity of N2-fixation under low RZT and that inoculation with B. japonicum strains from cold environments is unlikely to enhance soybean N2-fixation under cool soil conditions. 相似文献
5.
本实验用平截末端连接法把卡那霉素抗性基因插入到大豆根瘤菌(Brahyrh;zobiumjaponicum)110的苹果酸脱氢酶(mdh)基因中,致使mdh基因失活,再通过电激法把这一重组基因转入大豆根瘤菌(Brahyrhizobiumjaponicum)2143中,进而探讨mdh基因失活对大豆固氮作用的影响。 相似文献
6.
L. Desprs F. J. Kruger D. Imbert-Establet M. L. Adamson 《International journal for parasitology》1995,25(12):1509-1514
The internal transcribed spacer region of the ribosomal RNA, ITS2, was sequenced from a singlé specimen of S. hippopotami collected from a pulmonary artery of the hippopotamus, Hippopotamus amphibius in South Africa. The nucleotide sequence was aligned with those of S. mansoni, S. rodhaini, S. haematobium, S. intercalatum, S. curassoni. S bovis and S. japonicum. Both maximum parsimony and genetic distance analyses were performed on these data sets. Using S. japonicum as outgroup to the African schistosomes, a single most-parsimonious tree was obtained of length 64 steps with a consistency index of 1. S. hippopotami was the sister-group to the remaining African species. This species has lateral-spined eggs and its basal position in the tree suggests that this condition is primitive and that terminal-spined eggs developed secondarily. Molecular data clearly show that S. hippopotami cannot be considered synonymous with S. mansoni. Assuming the hippopotamus is the normal host of S. hippopotami, phylogenetic analysis is consistent with an ancient association between schistosomes and ungulates. 相似文献
7.
日本血吸虫尾蚴发育的超微结构观察:Ⅱ.腺体 总被引:1,自引:1,他引:0
在透射电镜下观察不同发育期日本血吸虫尾蚴的腺体。结果:胚球期(S2)主要出现体细胞分裂与分化,首次证明分泌细胞及其小体在S2出现,雏体期(S3)见到前钻腺细胞体与钻腺管束及分泌小体。成熟前期(S4)钻腺分泌小体基质分A/B为主两型,分别演变为成熟期(S)5的后/前钻腺分泌小体。头腺分泌小体亦在S4出现。从前钻腺体排至头器远端腺管的分泌小体,显眼透明球消失成为致密同质性小体,已为大家共识。而在后钻腺 相似文献
8.
9.
John T. Sullivan Charles S. Richards Kian Joe Lie Donald Heyneman 《International journal for parasitology》1981,11(6):481-484
Sullivan J. T., Richards C. S., Lie K. J. and Heyneman D. 1981. Schistosoma mansoni, NIH-Sm-PR-2 strain, in non-susceptible Biomphalaria glabrata: Protection by Echinostoma paraensei. International journal for Parasitology11:481–484. Among seven inbred genetic stocks of Biomphalaria glabrata that are non-susceptible for the NIH-Sm-PR-2 strain of Schistosoma mansoni (PR-2), five stocks revert to nearly complete susceptibility when first infected with Echinostoma paraensei. These include both stocks in which PR-2 sporocysts are normally destroyed within 3–7 days, and stocks in which sporocysts often survive undeveloped for at least 3 weeks. Hence, these five stocks are resistant to but physiologically suitable for the development of PR-2. Of the two remaining stocks, one remains partly non-susceptible to PR-2, since less than 50 % of echinostome-infected snails revert to susceptibility, while the other stock remains completely non-susceptible to PR-2 following echinostome infection, due perhaps to a high level of residual resistance and/or unsuitability. 相似文献
10.
In juvenile albino Biomphalaria glabrata snails exposed for the first time to Echinostoma lindoense miracidia, and observed to be resistant, the sporocysts migrated to the heart at the same speed as they did in susceptible snails. However, in resistant snails the sporocysts were soon destroyed in the heart by amebocyte clumps. When these snails were then re-exposed to miracidia of the same species of trematode, the sporocysts were quickly destroyed soon after miracidial penetration, chiefly in the head-foot region. This strongly accelerated tissue reaction appears to have been induced by the previous contact with the same parasite. The sensitization of the snail tissues was highly specific: the hosts remained susceptible to Schistosoma mansoni and Paryphostomum segregation (Echinostomatidae), although partial resistance was observed against Echinostoma paraensei and E. liei, which are closely related to E. lindoense. 相似文献