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81.
在水稻遗传转化过程中发现一个不含外源基因的条斑和颖花异常的双突变体。该突变体的茎、叶、穗出现条斑。在分蘖盛期,一些叶片开始分岔或卷曲;花器官数目增多,表现为多内外稃,叶片状浆片,或浆片增大,雌雄蕊增多,颖花开裂。透射电镜对叶片白色组织细胞超微结构观察,发现细胞壁内陷,质体结构异常,不能发育出正常叶绿体所具有的片层和类囊体。叶绿素总含量和净光合速率明显低于野生型。突变体绿色组织部分中的细胞生长正常,但细胞较大。利用扫描电镜对花器官形态发生过程进行观察,雄蕊原基发育严重不同步,原基大小也不一样;心皮原基较小。 相似文献
82.
The olive tree (Olea europaea L.) is a very important evergreen fruit tree because of the high interest of olive oil and table olives in the human diet. Differentiation of olive floral buds during winter is strictly related to flowering during spring and finally to fruit production during autumn–winter. In order to determine which are the developmental events in differentiating olive floral buds we studied in four olive cultivars “Amfissis”, “Kalamon”, “Manzanillo” and “Chalkidikis” the anatomical progress of the ontogeny using median longitudinal sections of floral buds (cutting odd nodes), in weekly intervals from early February (initiation of differentiation) to mid-April (one week after floral bud burst) keeping the cultivars under the same environmental conditions. At the same time, we determined the changes in their water extractable proteins, as an index of the meristematic activity. At the beginning of differentiation, floral buds consisted of the apical and one pair of developed (odd) axillary meristems which were covered with the corresponding bracts. Floral buds showed a slow gradual enlargement in all cultivars. The sequence of the developmental events (initiation of intense mitotic activity in the apical and the first axillary meristems, initiation of mitotic activity in the second axillary meristem, development of the third pair of bracts (except from cv. Chalkidikis), appearance of mitotic activity in the third axillary meristem, swelling of apical and axillary meristems and appearance of primordial whorls) are presented comparatively. All cultivars showed similar ontogenetic trends but there were temporal differences in the initiation, the progress and the completion of the process. Cv. Amfissis initiated differentiation one week later compared to the other cultivars, also delaying the development of the second and the third axillary meristems. On the other hand, cvs. Kalamon and Chalkidikis delayed one week to complete the process when compared to cvs. Amfissis and Manzanillo. 相似文献
83.
We studied biotic and abiotic factors that influence pollination in two sympatric winter flowering species. Helleborus foetidus and Helleborus bocconei flower simultaneously in winter. Although climatic conditions are not favorable for biotic pollination both species rely mainly on large bees of the genus Bombus. At the beginning of flowering, harsh climatic conditions are restrictive for insect visits. As flowering continues and temperatures rise, pollinator activity increases. The two plant species share pollinators that visit them indiscriminately. The flowers of the two species differ in form and insects visit H. foetidus by inserting their heads and H. bocconei ventrally: pollen load on insects is highly specialized. With the arrival of spring, many other species start to bloom and in spite of the large number of flowers still on the plants insects abandon Helleborus species. At the end of spring increasing biotic interactions take away pollinators from the Helleborus species. 相似文献
84.
对大叶相思(Acacia auriculiformis)栽培植株进行观察,用光学显微镜和扫描电子显微镜(SEM)对其花部形态和开花生物学特征进行研究。结果表明,大叶相思开花期为8~12月,穗状花序由114.9±11.9朵花组成,每朵花含124.1±16.5枚雄蕊,每雄蕊含有8粒16合花粉,单花花粉量为15885粒;雌蕊1枚,具14.4±1.8个胚珠,柱头凹陷,属于湿柱头类型。P/O值为1103.1;大叶相思花在夜间开放,开花可分为5个阶段。开花期间观察到雌蕊先于雄蕊伸出花冠和雄蕊先于雌蕊伸出花冠并存的现象,推测雌雄基本同熟。SEM观察花药在开花的第2阶段形成开裂线,第4阶段完全开裂并开始散粉。雄蕊于开花第1天的9: 00~12: 00大量散粉;雌蕊柱头在开花第1天上午出现分泌物,随后逐渐减少。开花后3~4 d柱头开始凋零,柱头可授期约为3 d,以开花第1天10: 00之后的可授性最佳。 相似文献
85.
Integrins are cell adhesion molecules that mediate numerous developmental processes in addition to a variety of acute physiological events. Two reports implicate a Drosophila beta integrin, betaPS, in olfactory behavior. To further investigate the role of integrins in Drosophila olfaction, we used Gal4-driven expression of RNA interference (RNAi) transgenes to knock down expression of myospheroid (mys), the gene that encodes betaPS. Expression of mys-RNAi transgenes in the wing reduced betaPS immunostaining and produced morphological defects associated with loss-of-function mutations in mys, demonstrating that this strategy knocked down mys function. Expression of mys-RNAi transgenes in the antennae, antennal lobes, and mushroom bodies via two Gal4 lines, H24 and MT14, disrupted olfactory behavior but did not alter locomotor abilities or central nervous system structure. Olfactory behavior was normal in flies that expressed mys-RNAi transgenes via other Gal4 lines that specifically targeted the antennae, the projection neurons, the mushroom bodies, bitter and sweet gustatory neurons, or Pox neuro neurons. Our studies confirm that mys is important for the development or function of the Drosophila olfactory system. Additionally, our studies demonstrate that mys is required for normal behavioral responses to both aversive and attractive odorants. Our results are consistent with a model in which betaPS mediates events within the antennal lobes that influence odorant sensitivity. 相似文献
86.
87.
Salt, known as taste quality, is generally neglected in olfaction, although the olfactory sensory neurons stretch into the salty nasal mucus covering the olfactory epithelium (OE). Using a psychophysical approach, we directly and functionally demonstrate in the awake rat for a variety of structurally diverse odorants that sodium is a critical factor for olfactory perception and sensitivity, both very important components of mammalian communication and sexual behavior. Bathing the olfactory mucus with an iso-osmotic sodium-free buffer solution results in severe deficits in odorant detection. However, sensitivity returns fully within a few hours, indicating continuous mucus production. In the presence of sodium in the mucus covering the OE, all odorants induce odorant-specific c-Fos expression in the olfactory bulb. Yet, if sodium is absent in the mucus, no c-Fos expression is induced as demonstrated for n-octanal. Our noninvasive approach to induce anosmia in mammals here presented--which is fully reversible within hours--opens new possibilities to study the functions of olfactory communication in awake animals. 相似文献
88.
89.
Nymphaea and Nuphar (Nymphaeaceae) share an extra-axillary mode of floral inception in the shoot apical meristem (SAM). Some leaf sites along the ontogenetic spiral are occupied by floral primordia lacking a subtending bract. This pattern of flower initiation in leaf sites is repeated inside branching flowers of Nymphaea prolifera (Central and South America). Instead of fertile flowers this species usually produces sterile tuberiferous flowers that act as vegetative propagules. N. prolifera changes the meristem identity from reproductive to vegetative or vice versa repeatedly. Each branching flower first produces some perianth-like leaves, then it switches back to the vegetative meristem identity of the SAM with the formation of foliage leaves and another set of branching flowers. This process is repeated up to three times giving rise to more than 100 vegetative propagules. The developmental morphology of the branching flowers of N. prolifera is described using both microtome sections and scanning electron microscopy. 相似文献
90.
Odor presentation generates both fast oscillations and slow patterning in the spiking activity of the projection neurons (PNs)
in the antennal lobe (AL) of locusts, moths and bees. Experimental results indicate that the oscillations are the result of
the interaction between the PNs and the inhibitory local neurons (LNs) in the AL; e.g., blocking inhibition by application
of GABA-receptor antagonists abolishes these oscillations. The slow patterning, on the other hand, was shown to be somewhat
resistant to such blockage. In a H-H model, we reproduce both the oscillations and the slow patterning. As previously suggested,
the oscillations are the result of the interaction between the PNs and LNs. We suggest that calcium and calcium-dependent
potassium channels (found in PNs of bees and moths) are sufficient to account for the slow patterning resistant to the application
of GABA-receptor antagonists. The intrinsic bursting property of the PNs, resulting from these additional modeled currents,
give rise to another network feature that was seen experimentally in locusts: A relatively small increase in the number of
additional generated PN action potentials when LN input is blocked. Consequently, the major effect of network inhibition is
to redistribute the action potentials of the PNs from bursting to one action potential per cycle of the oscillations.
Action Editor: Christiane Linster 相似文献