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201.
争胜鼠的上门齿釉质结构分为两层。内层施氏明暗带界线清楚,呈横向延伸,带宽不规则,主要为1个釉柱宽。釉柱间质很发育,围绕釉柱,其微晶方向与釉往平行,属单系。争胜鼠与始鼠科共有单系门齿微细结构,而与先松鼠科共有始啮型头骨的特征,因前者为较进特征而后者为近祖的原始特征,故争胜鼠与始鼠科有较近的系统关系。  相似文献   
202.
与南京汤山直立人伴生的偶蹄类及其古环境浅析   总被引:8,自引:2,他引:6  
董为 《人类学学报》1999,18(4):270-281
在汤山葫芦洞大洞发现的偶蹄类化石共有 4个科、 5个属种 ,其中化石毛冠鹿为首次在华东地区发现。除德氏水牛相似种以外 ,其它属种与周口店第 1地点的标本相比具有个体较大(如李氏野猪、葛氏斑鹿和肿骨鹿 )或形态较进步 (如李氏野猪、似德氏水牛 )。这些动物所反映的古环境为植被丰富 ,并以阔叶乔木和灌木为主 ,间有局部开阔草地。当时的年平均气温与现在相似 ,但冬季偏冷。  相似文献   
203.
本文以126例生育年龄非妊娠女工的髂结节间径、髂前上棘间径、大转子间径及坐骨结节间径为自变量估计因变量中骨盆横径,求出多元回归方程:=—6.89+0.05x_1+0.12x_2+0.23x_3+0.77x_4;以骶耻外径和骨盆倾斜度为自变量估计因变量中骨盆矢径,其回归方程为:=6.09+0.39x_1-0.05x_2。对两方程进行方差分析,其F值分别为4.069和8.26,均具高度显著性,可以应用于临床对中骨盆径的估计以取代X线测量法。  相似文献   
204.
A comparative study of middle layer both in sterile and fertile anthers of Tai Gu wheat was made on electron-microscopic level. The submicroscopic structure of middle layer in fertile form was found that its middle layer degeneration was somewhat later than the period mentioned in literatures, and lasted somewhat as long as that of tapetal layer. On the other hand, there was a tendency of early disintegration of middle layer in sterile anthers. When abnormal meiosis of pollen mother cells was progressing and followed by pollen mother cells abortion one after another, the middle layers degenerated gradually, and appeared as irregular dark regions or empty spaces.  相似文献   
205.
本文扼要介绍近年来日本旧石器早、中期考古的新发现,以及在年代学、文化分期、技术与类型学方面的研究工作的新进展。作者在此基础上探讨了日本旧石器中期向晚期的过渡,以及日本列岛旧石器早、中期文化与东北亚大陆同期文化的对比。  相似文献   
206.
New data and records of the genus Chrysotoxum Meigen, 1803 are reported, arising from taxonomic and faunistic examination of adult specimens collected from 1920 to 2011 from four northeastern provinces of Turkey (Erzurum, Bayburt, Kars, and Artvin), and from the neighboring countries of Armenia, Azerbaijan and Iran. Three new species are described: Chrysotoxum antennalis Vuji?, Nedeljkovi? &; Hayat sp. n., C. clausseni Vuji?, Nedeljkovi? &; Hayat sp. n. and C. persicum Vuji?, Nedeljkovi? &; Hayat sp. n. The first two are known only from northeastern Turkey, and the third also occurs in Armenia, Azerbaijan and Iran. These new species have in common an antenna with the basoflagellomere being shorter than the scape and pedicel together.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:4C264678-8E47-4DE0-AC7D-91DABC597BCD  相似文献   
207.
根据一件产自云南罗平中三叠世关岭组Ⅱ段的新标本并结合产自相同地点和地层中的模式标本对纤细滇美龙(Dianmeisaurus gracilis Shang & Li,2015)进行了详细研究.原模式标本暴露其腹而,而新标本暴露其背面,两者互相补充提供了更完整、精确的纤细滇美龙解剖学信息.新材料揭示该种具有非常短小的吻部,眶前区的长度不仅短于眶后区长度,甚至短于眼眶的长度;外鼻孔小且位置靠前,即鼻孔前区的长度短于鼻孔后缘与眼眶前缘之间的距离;由两额骨构成的眼眶间隔非常狭窄,宽度小于顶骨平台宽度的1/3;额骨前后两端均具渐尖的突起;顶骨后部不收缩,顶骨平台后缘呈深V型.补充了新信息和包含更多属种(如Dawazisaurus)后的系统发育学分析支持了之前滇美龙和滇东龙互为姊妹群的结论,同时它们和马家山龙、滇肿龙、贵州龙和大洼子龙一起构成了一个仅由中国的属种组成的单系类群.与欧洲肿肋龙类群(Dactylosaurus,Anarosaurus,Serpianosaurus和Neusticosaurus)相比,这一单系类群与幻龙类有更近的亲缘关系.  相似文献   
208.
The Givetian platform of the Ardennes Massif records several alternations between a siliciclastic‐carbonate ramp and a carbonate shelf. Usually these depositional contexts are considered as a major disruption implying a perturbation of many ecological parameters. We established the impact of these variations on the biodiversity structure through the study of the trophic organisation. Thanks to a previous microfacies analysis, 550 levels of the Mont d'Haurs section in Givet and ten associated environments were precisely defined. Seven palaeotrophic levels are recognized from micropalaeontological data, including benthic, planktonic, heterotroph and autotroph organisms. The spatial and temporal distributions of these levels have been analysed through means of multivariate analyses. The statistic results show that the distribution of the palaeotrophic levels during periods characterized by a mixed ramp is not significantly different than during carbonate shelf influences. These environmental modifications do not affect the community‐type. These results support recent studies performed on different benthic communities occurring in the Givetian of the Ardennes Massif. Indeed, trilobite and ostracod faunas of this period appear more affected by global environmental changes as the Ka?ák (uppermost Eifelian) and Taghanic (late middle Givetian) events. Moreover, along the proximal‐distal transect on the platform, the reef constitutes the most singular environment. However, contrary with the Frasnian reefs of the Ardennes Massif, which consist of carbonate mud mounds laying on a deep mixed ramp, there is no trilobite community that appears restricted to Givetian reefs. Thus global bioevents during the Middle Devonian have a more important control on the biodiversity than the platform morphology. These results support the view that at wide scales (spatial and temporal), the biodiversity responds more positively to ecological disturbances.  相似文献   
209.
The Bohemo‐Iberian regional scale for South Gondwana, involving the ‘Mediterranean Province’, comprises five regional stages (Arenigian, Oretanian, Dobrotivian, Berounian and Kralodvorian) plus the global Tremadocian and Hirnantian. The predominance of shallow‐water taxa in those high‐latitude faunas imposes serious difficulties for correlating the regional succession with the formal global chronostratigraphy because of the almost total absence of the key graptolites and conodonts defining the base of the standard series, stages and stage slices. Instead, the abundant benthic faunas (trilobites, brachiopods, molluscs, echinoderms) of South Gondwanan origin largely dominated in the area from the middle Darriwilian to the late Katian. The poleward faunal migration of originally Avalonian, Baltic, Laurentian and even Asiatic taxa during the Boda Event of global warming progressively ends with the endemicity in the region, where the ensuing benthic assemblages were severely affected by the Hirnantian glaciation. The regional scale significantly improves the precision of correlations between Ordovician strata from SW and central Europe, North Africa and a large part of the Middle East. An updated record of palaeontological data from areas where Mediterranean faunas remain practically unknown, or are still poorly investigated, is also included. Palaeobiogeographical relationships based on the distribution of faunas across South Gondwana are suggested as an improvement for positioning many territories in modern palaeogeographical reconstructions and offer a constructive approach to problems related to the pre‐Variscan and pre‐Alpine orogenic puzzles.  相似文献   
210.
Glycine soja, also called wild soybean, is the wild ancestor of domesticated soybean (Glycine max), and one of the world's major cultivated crops. Wild soybean is a valuable resource for the breeding of cultivated soybean and harbors useful genes or agronomic traits. To use and conserve this valuable resource, we conducted a study to evaluate the genetic diversity and population structure of wild soybean using the sequencing data of two nuclear loci (AF105221 and PhyB) and one chloroplast locus (trnQ-rps16) of more than 600 individuals representing 53 populations throughout the natural distribution range. The results showed that most of the variation was found within the populations and groups, but significant genetic differentiation was also detected among different eco-geographical groups. Correlations between genetic and geographical distance at all the loci were consistent with the isolation by distance gene flow model. G. soja exhibited the highest genetic diversity in middle and downstream of Yangzi River (MDYR) region, followed by North East China (NEC), and was the lowest in North West China (NWC). We concluded that both in situ and ex situ conservation strategies required for wild soybean populations, especially which are native to MDYR and NEC regions.  相似文献   
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