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881.
Analysis of a morphological dataset containing 152 parsimony‐informative characters yielded the first phylogenetic reconstruction spanning the South American characiform family Anostomidae. The reconstruction included 46 ingroup species representing all anostomid genera and subgenera. Outgroup comparisons included members of the sister group to the Anostomidae (the Chilodontidae) as well as members of the families Curimatidae, Characidae, Citharinidae, Distichodontidae, Hemiodontidae, Parodontidae and Prochilodontidae. The results supported a clade containing Anostomus, Gnathodolus, Pseudanos, Sartor and Synaptolaemus (the subfamily Anostominae sensu Winterbottom) albeit with a somewhat different set of relationships among the species within these genera. Anostomus as previously recognized was found to be paraphyletic and is split herein into two monophyletic components, a restricted Anostomus and the new genus Petulanos gen. nov. , described herein. Laemolyta appeared as sister to the clade containing Anostomus, Gnathodolus, Petulanos, Pseudanos, Sartor and Synaptolaemus. Rhytiodus and Schizodon together formed a well‐supported clade that was, in turn, sister to the clade containing Anostomus, Gnathodolus, Laemolyta, Petulanos, Pseudanos, Sartor and Synaptolaemus. Anostomoides was sister to the clade formed by these nine genera. Leporinus as currently defined was not found to be monophyletic, although certain clades within that genus were supported, including the species with subterminal mouths in the former subgenus Hypomasticus which we recognize herein as a genus. Abramites nested in Leporinus, and Leporellus was found to be the most basal anostomid genus. The presence of cis‐ and trans‐Andean species in Abramites, Leporellus, Leporinus and Schizodon, all relatively basal genera, suggests that much of the diversification of anostomid species pre‐dates the uplift of the Andean Cordilleras circa 11.8 million years ago. Several important morphological shifts in anostomid evolution are illustrated and discussed, including instances of convergence and reversal. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 70–210.  相似文献   
882.
Based on morphological evidence, we newly define the genus Stenotaenia Koch, 1847 (=Scnipaeus Bergsøe & Meinert, 1866; =Simophilus Silvestri, 1896; =Onychopodogaster Verhoeff, 1902; =Insigniporus Attems, 1903; =Notadenophilus Verhoeff, 1928; =Bithyniphilus Verhoeff, 1941; =Schizopleres Folkmanova, 1956; =Euronesogeophilus Matic, 1972; all syn. nov. ) as including the following 15 species: Stenotaenia linearis (Koch, 1835) (=Geophilus simplex Gervais, 1835; =Geophilus brevicornis Koch, 1837; =Scnipaeus foveolatus Bergsøe & Meinert, 1866; =Himantarium caldarium Meinert, 1886 syn. nov. ; =Geophilus (Geophilus) linearis var. polyporus Verhoeff, 1896 syn. nov. ; =Geophilus ormanyensis Attems, 1903 syn. nov. , after lectotype designation; =Insigniporus acuneli C?pu?e, 1968 syn. nov. ) from central and northern Europe; Stenotaenia frenum (Meinert, 1870) from northern Africa; Stenotaenia romana (Silvestri, 1895) (=Geophilus silvestrii Verhoeff, 1928 syn. nov. ) and Stenotaenia sorrentina (Attems, 1903) (=Geophilus forficularius Fanzago, 1881 syn. nov. ; =Geophilus linearis abbreviatus Verhoeff, 1925 syn. nov. ) from the Italian peninsula and Sardinia; Stenotaenia antecribellata (Verhoeff, 1898) (=Simophilus albanensis Attems, 1929 syn. nov. ), Stenotaenia cribelliger (Verhoeff, 1898), Stenotaenia palpiger (Attems, 1903), Stenotaenia rhodopensis (Kaczmarek, 1970), and Stenotaenia sturanyi (Attems, 1903) from the Balkan peninsula; Stenotaenia naxia (Verhoeff, 1901) (=Geophilus graecus Verhoeff, 1902) from the Aegean islands; Stenotaenia asiaeminoris (Verhoeff, 1898) and Stenotaenia bosporana (Verhoeff, 1941) from Anatolia; Stenotaenia giljarovi (Folkmanova, 1956) from western Caucasus; Stenotaenia fimbriata (Verhoeff, 1934) and Stenotaenia palaestina (Verhoeff, 1925) from Palestine; with the only exception of S. linearis, all of these binomens are comb. nov. In Stenotaenia, a strongly conserved overall morphology is matched by an unusual interspecific variation in both the body size of fully grown specimens (from 1.7 cm in S. romana to 7.7 cm in S. sturanyi) and the number of leg‐bearing segments (from 43 in male S. romana to 115 in female S. sturanyi). The number of segments correlates with maximum body size. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 153 , 253–286.  相似文献   
883.
独叶草叶二叉分枝脉序中网结脉和盲脉的形态学研究   总被引:12,自引:1,他引:12  
对独叶草营养叶二叉分枝脉序及其中的网结脉和盲脉的形态学研究表明:(1)网结脉中2条完全汇合的与靠近脉中完全分离的叶脉之间未发现任何形式的维管束汇合的中间类型及网结脉中具有不同程度的连接脉退化痕迹的事实表明,网结脉不可能由靠近脉产生,相反,由于网结脉中联结脉的退化而形成开放脉;(2)盲脉是通过伴随着齿退化的达齿脉的退化、网结脉中联结脉的间断、非网结脉由分枝处间断三种方式产生的;(3)越裂片脉的出现及其可以形成网结脉的现象表明独叶草营养叶可能曾具有较为复杂的脉序,这种叶脉也呈现出退化的趋势;(4)独叶草营养叶的二叉分枝脉序可能是一种退化性状,而网结脉的出现可能是这种退化过程中的残留痕迹。  相似文献   
884.
To compare rectal gland morphology of bull sharks Carcharhinus leucas , animals captured in the freshwater reaches of the Brisbane River, Australia, were acclimated to sea water over 17 days with 1 week in the final salinity. A control group was left in fresh water for 17 days. Animals in fresh water and sea water were strongly hyper- and hypo-ionic with respect to plasma Na+ and Cl, respectively. This difference necessitates NaCl secretion by the rectal gland in sea water and conservation of NaCl in fresh water. Structural differences in the rectal gland of freshwater and seawater acclimated bull sharks were limited. There was no difference in rectal gland cross-sectional area, lumen area, rectal gland vein area, number of secretory tubules or secretory cells per secretory tubule in freshwater and seawater acclimated animals. At a cellular level, there was no difference between the degree of basolateral and lateral folding, number of mitochondria or number of desmosomes per tight junction. Tight junction width was significantly greater in seawater acclimated animals. The number of red blood cells in the interstitial tissue was also significantly higher in seawater acclimated animals, possibly as a result of increased blood perfusion of the secretory epithelia. The lack of major structural changes in the rectal glands of bull sharks acclimated to fresh water and sea water most likely represents the salinity gradient in the Brisbane River where animals are found throughout the river and can experience large fluctuations in salinity over short distances. Differences in rectal gland morphology of bull sharks in fresh water and sea water are discussed in terms of their relevance to osmoregulation in elasmobranchs.  相似文献   
885.
目的:促溶剂通常用于甾体生物催化过程以提高底物溶解度,但在发酵液中添加促溶剂对菌体形态及发酵液特性的影响还少有报道。方法:利用旋转流变仪和顺磁分析仪分别对发酵液的流变特性及体积氧传递系数KLa进行监测。结果:无论是否添加促溶剂,发酵液都表现出非牛顿流体力学特性,但添加3%1,2丙二醇后同一时期发酵液稠度系数减小大约17%,而流动指数平均增加8%。结论:添加促溶剂使得发酵液表观黏度减小,体积氧传递系数增大,从而有利于甾体化合物的生物转化。  相似文献   
886.
Pre-dispersal seed predators of quickly maturing inflorescences of Asteraceae are constrained by shortage of development time. At seed dispersal, they should pupate or, if still immature, relocate into another inflorescence. To investigate how dominant coleopteran predators of dandelion seed, Glocianus punctiger (Curculionidae) and Olibrus bicolor (Phalacridae), cope with time limitation we combined observation (development and temperature of dandelion capitulum, thermal constants of predator development, age structure of larval populations at seed dispersal) and analogy (“rate isomorphy” in predator development, comparing “model” coleopteran species with similar temperature requirements). Development of a dandelion capitulum takes 21 days. The time available to G. punctiger (140–190 day degrees, development threshold 6.3°C) is sufficient to complete development and pupate after seed dispersal. By contrast, only 30–50 day degrees are available to O. bicolor (threshold 13.5°C) and this is not enough to complete development and consequently immature larvae should move to other capitula to continue feeding until pupation. These contrast strategies which are determined by this thermal adaptation, are accompanied by differences in larval morphology. The “cold adapted” G. punctiger has an apodous larva not capable of migrating between capitula while the “warm adapted” O. bicolor has a mobile campodeiform larva capable of migration.  相似文献   
887.
大量采集新疆各地网衣属(LecideaAch.)地衣标本,发现1个中国新记录种L.hypocrita,4个新疆新记录种L.berengeriana,L.confluens,L.lactea,L.lithophila。文中对这些新记录地衣进行了详细描述,并提供了反映地衣特征的彩色图片。  相似文献   
888.
Synchrotron radiation X‐ray tomographic microscopy (SRXTM) was used to virtually dissect and peel the shields off of the microscopic, bivalved phosphatocopine crustaceans in the Cambrian ‘Orsten’ type of preservation of Sweden. Doing so opened up for an array of concealed internal structures to be observed in a fully enclosed specimen of Hesslandona ventrospinata and a semi‐enclosed specimen of Hesslandona angustata. For comparison, also a head‐larva stage specimen of H. angustata, with shields in ‘butterfly position’, was analysed. The X‐ray tomographic data sets revealed excellently preserved structures, such as labrum, sternum, antennae, mandibular and post‐mandibular limbs with their minute setae, all of which were more or less disguised by the enclosing shields. This, moreover, allowed assignment to growth stages of the specimens, which is impossible based solely on external morphology and size. Micro‐spherules observed inside the shields of the semi‐enclosed H. angustata specimen may represent remains of food particles, and the feeding biology of phosphatocopines is discussed in detail. Our analyses suggest that phosphatocopines were particle feeders. The SRXTM technique offers the ability to three‐dimensionally reconstruct the morphology in high resolution, construct virtual serial sections and study concealed structures. The resulting data allow for new structures to be revealed for previously known taxa and for new taxa to be identified, with the added benefit of not destroying the specimens in the process. Hence, we do not longer have to rely on serendipitous finds of broken and/or open phosphatocopine specimens to elucidate their diagnostic ventral morphology.  相似文献   
889.
用扫描电镜对唇成熟卵子及早期精子入卵过程进行观察.结果 显示,唇成熟卵子在动物极中央有一深凹陷的表面光滑的精孔器,其外径2.512 μm,内径2.330 μm,精子直径1.567 μm.混匀的精卵刚遇水时,没有精子进入精孔器.受精后1 s,精孔器内出现精子.受精后5 s,组织切片显示,精子已经进入卵子内,并形成具有强烈抑制多精入卵作用的受精锥.受精后10 s,精子在精孔器前庭集结,尚未形成受精塞.受精后20 s,在精孔器内形成受精塞.受精塞没有阻塞精孔管,经分析它不是来源于皮层反应产物.受精塞形成后,可以吸附入卵的精子,这对多精入卵有积极的抑制作用;精子尾部在入卵过程中相互缠绕,这也是减少多精入卵的重要机制.受精后30 s, 受精塞和吸附的精子向精孔器外移动.受精后50 s, 受精塞和吸附的精子堵塞精孔器.受精后60 s, 受精塞吸附的精子开始解体,但是由于精孔管未封闭,还有精子通过精孔管进入到质膜.在人工受精过程中,卵子的单精受精屏障会因其周围精子密度大、精子与卵子距离短、精子运动速度快而被打破,从而导致这些卵子出现多精入卵的现象.受精后80 s, 精孔管仍然没有封闭,精孔器附近的精子明显出现活动能力的差异:精孔器外面的精子活动能力最强,精孔管旁边的精子活动能力较弱;精孔管外堆积的精子活性消失,受精塞吸附的精子已开始解体,经初步分析,这可能是进入其内的精子耗能有所差异的结果.受精后100 s,受精塞吸附的精子解体.  相似文献   
890.
The genus Oxystele, a member of the highly diverse marine gastropod superfamily Trochoidea, is endemic to southern Africa. Members of the genus include some of the most abundant molluscs on southern African shores and are important components of littoral biodiversity in rocky intertidal habitats. Species delimitation within the genus is still controversial, especially regarding the complex O. impervia / O. variegata. Here, we assessed species boundaries within the genus using DNA barcoding and phylogenetic tree reconstruction. We analysed 56 specimens using the mitochondrial gene COI. Our analysis delimits five molecular operational taxonomic units (MOTUs), and distinguishes O. impervia from O. variegata. However, we reveal important discrepancies between MOTUs and morphology-based species identification and discuss alternative hypotheses that can account for this. Finally, we indicate the need for future study that includes additional genes, and the combination of both morphology and genetic techniques (e.g. AFLP or microsatellites) to get deeper insight into species delimitation within the genus.  相似文献   
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