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991.
植物未减数配子及其应用研究进展   总被引:12,自引:1,他引:11  
  相似文献   
992.
In this paper, some results of the study on the sporepollen of the Yanghugou Formation in the western Shaan-Gan-Ning (Ordos) Basin of Northwest China axe reported. Plenty of well preserved microfossil, which 136 types belong to 62 microspore genera and one megaspore genus, including 2 new genera , 13 new species, I Acritarch (Chamosphaera pseudozonatus gen. et sp. nov.), from 8 bore-holes and outcrop have been discribed. In generally, the microfiora of the Yanghugou Formation is similar to the Taiyuan Formation (Upper Carboniferous). According to the spore-pollen assemblage of Yanghugou Formation may correlate with those in the Middle Carboniferous of Great Britain, Belgium the north of France, German and North America. Besides, the assemblage are similar to Middle Carboniferous of Nortth Shandong and Hengshanbu of Ningxia in the microfossil assemblage. The geological age of the beds is considered to Late of Middle Carboniferous.  相似文献   
993.
A new genus and species Pinnatiramosus qianensis is described from the Xiushan Formation of Middle Silurian (Wenlockian)in the north of Guizhou, China. This plant consists of a prostrate axis and erect pinnate branching system. Conductin gbundle is comprised of tubular cells with scalariform or alternate simple pits. Pinnatiramosus gen. nov. Diagnosis: Plant cylindrical, differentiated into erect branches and prostrate axes; erect branches much branched, consisting of regular or irregular pinnate lateral branches; laterals opposite or alternate, with basal parts constricted and acute or blunt apices. Conducting bundle comprised of longitudinally aligned tubes with secondary thickening. Reproductive structures nor seen. Derivation of name: Pinnatus (Latin)=pinnate and ramosus (Latin)=ramose, referred to the external morphology of the plant. Pinnatiramosus qianensis sp. nov. Diagnosis: Characters described as the genus. Prostrate axes at least 400 mm in length and 3–6 mm in diameter, produced erect longer branches and downward shorter branches; erect branches up to 200 mm long and vary from 1.0 to 2.5mm in diameter, branched at least six orders, with lateral branches unequally developed, long laterals scattered among short ones; lateral branches oppositely or alternately arranged on main axis, 1–3 mm: apart; ultimate bran- ches 0.4–0.8 mm in diameter, with acute or blunt apex; borne at angles of 40–70˚ with main axis. Conducting bundle ca. 1/4 of the axis diameter, composed of tubular elements with secondary thickening; tubes range from 15–54μm in diameter, with blunt end wall; secondary wall averages 4.86 μm in thickness, ranging 2.5–6.6 μm, with scalariform and alternate pits. Derivation of name: Qian is the abbreviation for Guizhou province from where the plants are found. In this paper, is made the comparison of this new plant with fossil and living algae as well as early vascular plants on the basis of its external morphology and internal structure According to the comparison, Pinnatiramosus belongs to one of specialized plants with tracheophyte- like conducting tissue. Some interesting opinions are here provided as follows: (i) Silurian is, an important age of plant evolution. During this period certainly coexist not only various algae and undoubted vascular plants but also a group of interesting plants that were just immigrating from aquatic to terrestrial environments. (ii) The transmigration of algae from water to land occurred along several different evolutionary lines. Accompanying changes of these algae on morphology and anatomy were adapted to terrestrial environments. (iii) Pinnatiramosus represents a group of new plants with remarkably nontracheophyte morphology but tracheophyte- like anatomy. (iv) The tracheid-like tubes, macerated out of Silurian rocks, derived more probably from non-vascular plants such as Pinnatiramosus, Prototaxitesor Nematothallus than from vascular plants.  相似文献   
994.
This paper deals with some Middle Jurassic fossil plants from southern margin of the Eerduosi Basin. There are 36 species in 13 genus in this flora, i.e. Equisetum multi- dentatus Oishi, E. sp., Coniopteris hymenophylloides (Brongn.) Seward, C. bella Harris, C, burejensis (Zalessky) Seward, C. szeiana Choweet Yeh, C. tatungensis Sze, C. spp., Todites williamsoni (Brongn.) Seward, T. cf. williamsoni (Brongn.) Seward, Cladophle- bis asiatica Chow et Yeh, C. argutula (Heer) Fontaine, C. hsiehiana Sze, C. ( Gleichenites) takeyamae Oishi et Takahasi, C. cf. gracils Sze C. triangularis Oishi, C. grabauiana P’an C. cf punctata (Thoms) Chow et Yeh, C. spp., Baiera cf. concinna (Heer) Kawasaki, B. furcata (L. et H.) Braun, B. sp., Sphenobaiera longifolia (Pomel) Florin, Ginkgo obrutchewi Seward, G. sp., Phoenicopsis angustifolia Heer P. manchurica (Yo- koyama) Yabe, p. sp., Czekanowskia rigida Heer, C. sp., Pterphyllum sp., Elatocladus cf manchurica (Yokoyama) Yabe, E. sp., Podozamites lanceolatus (L. et. H.) Braun P. sp., Carpolithus sp. etc. The dominant groups of this flora are Filicopsida and Ginkgopsida. So it could be compared with the flora of Yanan Formation from inner Earduosi Basin and other floras from Northeast, Northwest and China, such as the floras of Dutung, Mentougon and Dongsheng etc. This flora is different from the Late Triassic flora and the Early Jurassic flora of North China. It belongs to the Coniopteris-Phoenicopsis flo- ra, which was assigned to Early-Middle Jurassic flora by Prof. Sze. But after studying, the authers believe that this flora should belong to Middle Jurassic rather than Early Jurassic. The climate was warm and damp in that time in North China.  相似文献   
995.
The effects of the exogenous auxin——NAA, kinetin and wound on the callus formation of the cotyledon of mung bean (Phaseolus radiatus L.) with relation to the biosyntheses of endogeonous tryptophan (Trp) and IAA have been studied. The results indicate that wound plays an important role in the callus formation. The size of wounded surface is directly proportional to the proliferation of the callus tissue. The levels of free Trp and endogenous 1AA decreased in the initial period of the callus formation of mung bean cotyledon but increased in the later period. The substitution of L-Trp for NAA in the culture medium would play almost the same role in the callus proliferation. It has proposed that the exogenous phytohormones affect the biosyntheses of endogenous Trp and IAA, thereafter induce the callus formation. The wound has an important synergism with the phytohormones in this process.  相似文献   
996.
Ovules (or seeds) are distributed widely in the beds of Paleozoic of China, but what have been found are all impressions or molds of them. Recently, while studying the fossil plants in coal balls of Coal Seam No.7 (P1) at the upper part of Taiyuan Formation in Xishan Coal- Field, Taiyuan, Shanxi Province, We found a kind of petrified ovules with internal structures, which not only are abundant but also quite well presserved. Having been studied, they are put into Cardiocarpus Brongniart and considered as a new species C. samaratus. In the coal bails they are often found associated with the leaves, stems and fructifications of Cordaites, so it is very possible that these ovules belong to Cordaites. It is very interesting that these ovules are very similar to those of the earliest conifers Lebachia described by G. M. Rothwell in 1982. This indicates' that there is a close relation between Cordaites and conifers. Cardioearpus samaratus ap.nov. The ovules are small, flat and obviously-winged. The average length is 6–7mm. The largest width (nearly equal to the length) is at the lower middle part of the ovule. Wings and the top and base of the ovule bend to the same side in a varying extent. The ovule is not cordate at the base. The integument can be divided into three layers: the sarcrotesta consisting of parenchymatous cells, the sclerotesta and the endotesta consisting of longitudinally-elongated sclerenchymatous and parenchymatous cells. The lower midrile part of the nucellus is vascularized. The micropyle is elliptical in transverse section. One main vascular bundle extends upwards from the base. Before it arrives at the sclerotesta, it biforcates into two vascular bundles and extend upwards in the sarcrotesta at the wings. In the meantime, the main vascular bundle continues' to extend upwards and passes across the sclerotesta and reaches the base of the nucellus from where it extends into the nucellus.  相似文献   
997.
The Couderousse Member of the Blacourt Formation in the Banc-Noir quarry, Ferques inlier, Boulonnais (Pas-de-Calais, France) has yielded a tooth plate whose morphology is similar to that of Synthetodus, which is considered a holocephalan. Its histology is made of an outer enameloid-like tissue, and an inner trabecular dentine. Its occlusal surface shows a bean-shaped bulge. This tooth plate was prepared from a limestone that is dated from the Middle–Upper varcus Conodont Zone, that is lower upper Givetian. This limestone has also yielded a Pokorninella bricae–Rothpletzella–Tentaculites assemblage, which is indicative of an environment of the inner to middle marine platform boundary. This specimen appears to be the oldest confirmed holocephalan (‘bradyodont’) tooth plate for which the name Melanodus loonesi nov. gen. et sp. is erected.  相似文献   
998.
记中国辽宁西部九佛堂组发现的中国翼龙一新种   总被引:10,自引:0,他引:10  
根据发现于辽宁省西部下白垩统九佛堂组的—小型翼手龙类骨架,建立一新种:谷氏中国翼龙Sinopterus gui sp.nov.。它的吻端直而尖锐,其下颌发育—明显的脊突。肱骨的三角脊发育,其末端没有扩展,呈四边形。翼掌骨的长度稍微短于飞行指第一指节的长度。股骨与胫骨之比率小,乌喙骨短于肩胛骨,联合背椎只有椎体相互愈合。虽然它与董氏中国翼龙相似,但是存在明显区别,比如个体较小,而大多数背椎椎体相互愈合等。谷氏中国翼龙是目前在辽西及其周边地区所发现最小的没有牙齿的翼手龙类。  相似文献   
999.
吉林延边早白垩世大拉子组植物化石新类型--星学异麻黄   总被引:6,自引:0,他引:6  
陶君容  杨永 《古生物学报》2003,42(2):208-215
报道产自吉林省延边早白垩世大拉子组植物化石新类型——星学异麻黄(Alloephedra xingxuei gen.et sp.nov.)。大拉子组的时代处于早白垩世的阿普特期-阿尔必期(Aptian-Albian)。化石标本保存了植物的茎枝、雌球花及种子;该种的茎枝分节,节间具细纵槽纹,叶退化,雌球花单个着生于小枝顶部,种子成对且种子顶部宿存珠孔管等特征与现存麻黄科植物最为相近,因此可能属于麻黄科。  相似文献   
1000.
伊朗卡尚地区始新世沟鞭藻类   总被引:3,自引:1,他引:2  
文章简要报道了伊朗卡尚地区库姆组首次发现的沟鞭藻类。计6属6种。根据沟鞭藻化石组合面貌,并结合介形虫和钙质超微化石组合。探讨了含沟鞭藻化石的地层时代.推测其沉积环境为正常浅海大陆架环境。  相似文献   
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