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101.
中国玛蚱属的分类研究及四新种记述(蚱总科:短翼蚱科) 总被引:5,自引:0,他引:5
本文系统研究分布于我国玛蚱属 Mazarredia Bolivar 的种类, 共计有12种, 其中有4新种, 即长翅玛蚱 Mazarredia longipennis sp. nov., 短背玛蚱 M. brachynota sp. nov., 罗城玛蚱 M. lochengensis sp. nov. 及瘤背玛蚱 M. torulosinota sp. nov.。文中记述了每个种的引证和分布地区, 给出了分种检索表。模式标本保存于陕西师范大学动物研究所。图11表4参12 相似文献
102.
茄科天仙子族的叶表皮特征及其系统学意义 总被引:16,自引:2,他引:14
在光学显微镜和扫描电镜下,观察了茄科天仙子族7属21种及其邻近类群2属3种共24种植物的叶表皮特征。结果表明:气孔器在各种植物的上、下表皮均有分布,多为无规则型,也有不等细胞型;叶表皮细胞形状有不同规则形、十字形、近长圆形和不规则多边形,垂周壁较平直、浅波状、波状或深波状。在扫描电镜下可见:叶表皮气孔器外拱盖内缘近平滑、浅波状或波状;角质膜多为具条纹,也有同时具条纹和颗粒或鳞片,偶尔仅具颗粒和鳞片 相似文献
103.
Fang Fang 《Ichthyological Research》2000,47(1):13-26
The three barredDanio species known from the Irrawaddy River drainage are redescribed. Two species are known from southwestern Yunnan:Danio interruptus in the Husa He and Longchuan, Jian watersheds, andD. apogon abundantly in the main river and tributaries of the Daying Jiang basin. The third species,D. shanensis, occurs in the Myitnge basin of northern Shan State, Myanmar.Danio interruptus differs from other barredDanio species by having a short, incomplete lateral line, a deeper head, and shorter thicker dark vertical bars or blotches anteriorly
on the sides.Danio shanensis has the lateral line either complete or incomplete, lesser head depth, and a series of deeper narrower vertical bars.Danio apogon has no lateral line, narrow or indistinct dark vertical bars, and a wide, but indistinct, horizonatal P stripe.Danio choprae, previously considered, as a barredDanio species, is more closely related to theD. dangila species group. 相似文献
104.
105.
Based on corresponding ascocarp ontogeny and thallus structure, the genera Euopsis and Harpidium are included in the family Lichinaceae. In the two species of Euopsis, E. granatina and E. pulvinata, the apothecia develop from ascogonia in generative tissue, while in H. rutilans they are pycnoascocarps. In thallus anatomy, the species of Euopsis resemble Pyrenopsis haematopsis and allied species, while H. rutilans corresponds in structure and development of the thallus and apothecia to Pyrenopsis haemaleella (syn. P. sphinctotricha). H. rutilans is the first member of Lichinaceae known to have only a green algal symbiont. In E. granatina, two phycobionts are always present, a species of Gloeocapsa and a chlorococcalean alga. In Euopsis and Harpidium, the ascus wall is composed of an outer, non-expansible and an inner, expansible layer; the latter surrounds the protoplast as an amyloid collar, which expands during spore release into a long, tapering rostrum. In Euopsis, the outer wall layer is strongly amyloid and the upper part separated from the expanded amyloid rostrum by a non-amyloid zone, appearing like a slit in LM studies. The ultrastructure and function of the ascus in E. granatina has been studied in TEM and is interpreted as functionally unitunicate-rostrate. Unitunicate asci with short rostrum are described for P. haemaleella and P. haematopsis. 相似文献
106.
107.
Diverse effects of invasive ecosystem engineers on marine biodiversity and ecosystem functions: A global review and meta‐analysis 下载免费PDF全文
Tamar Guy‐Haim Devin A. Lyons Jonne Kotta Henn Ojaveer Ana M. Queirós Eva Chatzinikolaou Christos Arvanitidis Serena Como Paolo Magni Andrew J. Blight Helen Orav‐Kotta Paul J. Somerfield Tasman P. Crowe Gil Rilov 《Global Change Biology》2018,24(3):906-924
Invasive ecosystem engineers (IEE) are potentially one of the most influential types of biological invaders. They are expected to have extensive ecological impacts by altering the physical–chemical structure of ecosystems, thereby changing the rules of existence for a broad range of resident biota. To test the generality of this expectation, we used a global systematic review and meta‐analysis to examine IEE effects on the abundance of individual species and communities, biodiversity (using several indices) and ecosystem functions, focusing on marine and estuarine environments. We found that IEE had a significant effect (positive and negative) in most studies testing impacts on individual species, but the overall (cumulative) effect size was small and negative. Many individual studies showed strong IEE effects on community abundance and diversity, but the direction of effects was variable, leading to statistically non‐significant overall effects in most categories. In contrast, there was a strong overall effect on most ecosystem functions we examined. IEE negatively affected metabolic functions and primary production, but positively affected nutrient flux, sedimentation and decomposition. We use the results to develop a conceptual model by highlighting pathways whereby IEE impact communities and ecosystem functions, and identify several sources of research bias in the IEE‐related invasion literature. Only a few of the studies simultaneously quantified IEE effects on community/diversity and ecosystem functions. Therefore, understanding how IEE may alter biodiversity–ecosystem function relationships should be a primary focus of future studies of invasion biology. Moreover, the clear effects of IEE on ecosystem functions detected in our study suggest that scientists and environmental managers ought to examine how the effects of IEE might be manifested in the services that marine ecosystems provide to humans. 相似文献
108.
Existing life cycle assessment (LCA) studies for furniture focus on single pieces of furniture and use a bottom‐up approach based on their bill of materials (BOM) to build up the data inventories. This approach does not ensure completeness regarding material and energy fluxes and representativeness regarding the product portfolio. Integrating material and energy fluxes collected at company level into product LCA (top‐down approach) over‐rides this drawback. This article presents a method for systematic LCA of industrially produced furniture that merges the top‐down approach and bottom‐up approach. The developed method assigns data collected at the company level to the different products while, at the same time, considering that wood‐based furniture is a complex product. Hence, several classifications to reduce the complexity to a manageable level have been developed. Simultaneously, a systematic calculation routine was established. The practical implementation of the developed method for systematic LCA is carried out in a case study within the German furniture industry. The system boundary was set in accord with the EN 15804 specification cradle‐to‐gate‐with‐options. The analysis therefore includes the manufacturing phase supplemented by an end‐of‐life scenario. The case study shows that the manufacturing of semifinished products (especially wood‐based panels and metal components) as well as the electric energy demand in furniture manufacturing account for a notable share of the environmental impacts. A sensitivity analysis indicates that up to roughly 10% of the greenhouse gas emissions are not recorded when conducting an LCA based on a BOM instead of applying the developed approach. 相似文献
109.
Helicobacter pylori infection reduces the risk of Barrett's esophagus: A meta‐analysis and systematic review 下载免费PDF全文
Bálint Erőss Nelli Farkas Áron Vincze Benedek Tinusz László Szapáry András Garami Márta Balaskó Patrícia Sarlós László Czopf Hussain Alizadeh Zoltán Rakonczay Jr Tamás Habon Péter Hegyi 《Helicobacter》2018,23(4)
Introduction
The prevalence of Helicobacter pylori infection (HPI) has been decreasing in developed countries, with an increasing prevalence of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) at the same time. The aim of our meta‐analysis was to quantify the risk of BE in the context of HPI.Methods
A systematic search was conducted in 3 databases for studies on BE with data on prevalence of HPI from inception until December 2016. Odds ratios for BE in HPI were calculated by the random effects model with subgroup analyses for geographical location, presence of dysplasia in BE, and length of the BE segment.Results
Seventy‐two studies were included in the meta‐analysis, including 84 717 BE cases and 390 749 controls. The overall analysis showed that HPI reduces the risk of BE; OR = 0.68 (95% CI: 0.58‐0.79, P < .001). Subgroup analyses revealed risk reduction in Asia OR = 0.53 (95% CI: 0.33‐0.84, P = .007), Australia OR = 0.56 (95% CI: 0.39‐0.80, P = .002), Europe OR = 0.77 (95% CI: 0.60‐0.98, P = .035), and North‐America OR = 0.59 (95% CI: 0.47‐0.74, P < .001). The risk was significantly reduced for dysplastic BE, OR = 0.37 (95% CI: 0.26‐0.51, P < .001) for non‐dysplastic BE, OR = 0.51 (95% CI: 0.35‐0.75, P = .001), and for long segment BE, OR = 0.25 (95% CI: 0.11‐0.59, P = .001) in case of HPI.Conclusions
This extensive meta‐analysis provides additional evidence that HPI is associated with reduced risk of BE. Subgroup analyses confirmed that this risk reduction is independent of geographical location. HPI is associated with significantly lower risk of dysplastic, non‐dysplastic, and long segment BE. 相似文献110.