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71.
Our investigations of diurnal variations of the 13C/12C ratio and CO2 content in soil air were carried out in three environments during periods of high biosphere activity. It has been observed that diurnal variation of CO2 concentration is negatively correlated 13. Particularly great variations occurred at shallow soil depths (10–30 cm) when the plant cover activity was high while the soil temperature was rather low. Under such conditions the 13 variations had the magnitude of 4, while the CO2 concentration varied more than doubly. The maximum of the 13C/12C ratlo and the minimum of the CO2 concentration in a cultivated field with winter wheat took place in the afternoon, whereas in deciduous forest similar patterns were observed at dawn. In these cases soil temperatures at 10 cm depths varied less than 2°C. Hence, under wheat the variation in root respiration rate seem to be the main reason of the recorded varations. In an uncultivated grass-field during the hottest period in summer we did not measure any distinct variations of CO2 properties in spite of the fact that soil temperature varied up to 5°C. This might be due to dominant microbial respiration at the high soil temperature, which exceeded 20°C. 相似文献
72.
Stanislaw Grzesiak Morio Iijima Yasuhiro Kono Akira Yamauchi 《Acta Physiologiae Plantarum》1997,19(3):349-357
Relatively little research has been conducted to determine different responses to drought among cultivars of the legume species.
The objective of this study was to identify differences in seedlings growth, water relations and leaf conductances resulting
from drought imposed on two field bean and two field pea cultivars that had been observed to differ in their drought tolerances,
and special emphasis was placed on the root system development.
Distinct differences between resistant and sensitive cultivars of field bean and field pea became evident in measurements
of the characteristics of the lateral root. The drought treatment induced statistically significant decrease in the number
of the developed laterals, their total length and dry matter. In the drought resistant cultivars (field bean Gobo and field
pea Solara) this reduction was smaller in comparison with sensitive ones (field bean Victor and field pea Bareness). The effect
of drought on growth of tap root in the drought resistant and drought sensitive cultivars was smaller and statistically not
significant. The results showed that drought resistant cultivars when compared with drought sensitive one would demonstrate
less abundance in the above-ground part and greater dimensions of the root system.
The measurements of leaf water potential and stomata diffusive resistance measurements indicate that the physiological reasons
for the different reactions to drought between the resistant and the sensitive field bean and field pea cultivars may be due
to a more effective protection of the level of tissue hydration and due to increase stomata diffusive resistance in the resistant
cultivars. During recovery period it has been also demonstrated that in the drought resistant cultivars a tendency exists
for a more complete return to the level of the control plants. 相似文献
73.
74.
Stanislaw Gill Wanda Dembínska-Migas Ewa Śliwíska Włodzimierz Maria Daniewskit Ferdinand Bohlmann 《Phytochemistry》1980,19(9):2049-2051
The aerial parts of Gaillardia grandiflora afforded two new pseudoguaianolides,9-O-desacetylspathulin-2-O-angelate 9-O-desacetylspathulin-2-O-isovalerate. The structures were elucidated by 1H NMR spectroscopic investigations by some chemical transformations. 相似文献
75.
Dr. J. Stanislaw Knypl 《Planta》1964,61(4):352-360
Summary Effect of 2,4-dinitrophenol, iodoacetic acid, mannitol, ribonuclease, CaCl2, phosphates, low oxygen tension, different temperatures, CCC and IAA on the coumarin-induced growth of sunflower hypocotyl sections have been investigated. Results indicate that coumarin-induced growth is auxin-like in type; nevertheless, the primary mode of coumarin action is probably quite different from that of IAA.With 4 Figures in the Text 相似文献
76.
77.
Guido Reifenberger Dr. Jürgen K. Mai Stanislaw Krajewski Wolfgang Wechsler 《Cell and tissue research》1987,248(2):305-313
Summary This study reports a specific cross-reactivity of the three anti-human-hematopoetic-cell monoclonal antibodies, anti-Leu-7 (HNK-1), anti-Leu-11a (NKP-15), and anti-Leu-M1 (MMA), with different epitopes in the brain of the adult rat. The distribution of these epitopes in rat brain is determined by means of immunohistochemistry in paraffin-embedded frontal serial sections.The reaction pattern of anti-Leu-11a monoclonal antibody is very similar to that of polyclonal antibodies against the myelin basic protein. Both antisera give a specific reaction with myelinated fibers. Immunoreaction products with the anti-Leu-7 monoclonal antibody are found as diffuse, mostly punctiform material in the neuropil and even more evident as small granules coating the cell surface of many neurons. In the white matter anti-Leu-7 reveals a moderate reactivity, which occurs predominantly as spots and fine-stranded material within the myelinated fiber tracts.Anti-Leu-M1 immunoreactivity is present between myelinated fiber bundles of the white matter, where it has a reticulate appearance, and as fine-granulated material within the grey matter of the cortex and the nuclei. The characteristic feature in the grey matter is that of irregularly shaped immunopositive plaques, which are often located around small blood vessels. The cytoplasm of glial and neuronal cells appeared negative with this MAB.The exact topographical distribution of the Leu-7 and Leu-M1 epitopes throughout the rat brain is described. The present hypotheses concerning the nature of this shared antigenicity between hematopoetic cells and nervous tissue are discussed.Supported by the Deutsche Forschungsgemeinschaft, SFB 200 相似文献
78.
Summary Transmission electron microscopy was used to study the effects of proteolytic enzymes (collagenase, trypsin, clostripain), the calcium chelator ethyleneglycol-bis-(-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA), and the calcium ionophore A 23187 on substrate adhesion and fine structure of chondrocytes and fibroblasts. Monolayer cultured cells responded to treatment with the proteolytic enzymes followed by EGTA or A 23187 by rounding and detaching from the substrate. This was accompanied by the formation of a microvillous surface, deep nuclear folds, and numerous cytoplasmic vacuoles. Labeling experiments with colloidal thorium dioxide indicated that the vacuoles were formed by endocytosis and fusion of endocytic vesicles with preexisting lysosomes. To a variable extent, similar changes were produced by trypsin or EGTA alone. The cells regained their normal fine structure after withdrawal of the reagents and when seeded onto a substrate. In suspension culture, recovery was incomplete; the cells retained a rounded shape and an increased number of cytoplasmic vacuoles.The results suggest that changes in plasma membrane composition and its permeability to calcium represent the primary signal for cell rounding and detachment. The cellular mechanisms responsible for the associated folding of the nuclear envelope and the cell surface remain unidentified. Nevertheless, this is believed to represent a means of handling of excess membrane during sudden transition from a flattened to a rounded shape. Membrane stored in folds and vacuoles is reutilized when the cells reattach and spread out on a substrate.Expert technical assistance was provided by Karin Blomgren and Anne-Marie Motakefi. Financial support was obtained from the Swedish Medical Research Council (06537), the King Gustaf V 80th Birthday Fund and from the Funds of Leiden University 相似文献
79.