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1.
Abstract

The two dominant environmental oscillations shape biology and survival of species: the day–night cycle and the succession of the seasons in the year. Organisms have adapted to anticipate these variations by evolving internal circadian (ca.- about, diem- day) and circannual clocks. The former enables the organisms to regulate physiological functions on a daily basis, and the latter on the annual basis. In mammals, the suprachiasmatic nuclei (SCN) of the anterior hypothalamus contain master pacemaker and orchestrate peripheral clocks in synchrony with the daily 24 h light-dark cycle, while in birds circadian pacemake is an interacting system principally located in the retina, pineal and the hypothalamus. In this mini review, we discuss the role of circadian clocks in regulation of seasonal timing in higher vertebrates, with reference to birds and mammals.  相似文献   
2.
北京动物园分别采用全人工和人工.狗乳交替哺育的方法,成功哺育6只雪豹幼崽。通过对育幼箱内外温、湿度的监测结果表明,幼崽呼吸频率随年龄增加而呈现周期性波动,9周后接近成年雪豹;幼崽体温0—87日龄呈逐渐下降趋势,50日龄后趋于稳定;排便和排尿量均随年龄增长呈增加趋势,70日龄增长量趋缓;幼崽体重直线增长。通过对两种哺育方式的卡方检验结果表明,两种哺育方式下雪豹幼崽体重生长存在显著差异。育幼箱内温度和幼崽自身体温对体重增长具有显著的影响;体温与幼崽呼吸频率和进食量具有显著的相关性。此外,还应注意饲料转换时机及微量元素对幼年雪豹生长发育的重要性。  相似文献   
3.
Blue light controls solar tracking by flowers of an alpine plant   总被引:2,自引:0,他引:2  
In at least 18 plant families, leaves or flowers can maintain a specific orientation with respect to diurnal movements of the sun. Previous work on heliotropic leaves has demonstrated that blue light (400–500nm) provides the cue for their tracking response. Floral heliotropism occurs in several families of arctic and alpine plants, but the spectral sensitivity of the response has not been studied previously. Moreover, no studies on the spectral sensitivity of any heliotropism have been conducted on wild plants growing in their natural habitat. Working under field conditions, we used coloured acrylic filters to determine whether heliotropism by flowers of the snow buttercup (Ranunculus adoneus) is responsive to broad-band blue or red light. Flowers were able to orient towards the sun under boxes made entirely of blue-transmitting filters and in red-transmitting boxes having a single blue side that faced the sun. In these treatments, solar tracking ability was not significantly different from that observed in adjacent control flowers. In contrast, the precision of solar orientation was significantly reduced in red-transmitting boxes and red boxes with a single blue side oriented away from the sun. In the early morning, flowers covered by red-transmitting boxes failed to orient in the direction of sunrise, suggesting that this floral response, unlike that seen in some heliotropic leaves, lacks a residual‘memory’ for previous solar movements.  相似文献   
4.
5.
高寒森林溪流微生物群落结构的季节性变化   总被引:2,自引:0,他引:2  
高寒森林溪流不仅是区域河流的源头,而且是联系陆地与水域的生态纽带。微生物活动可能成为控制溪流生态系统过程的关键因子,但其结构与动态过程缺乏必要关注。因此,结合同步温度动态监测,采用实时荧光定量PCR和DGGE技术,在2014年到2015年冻融季节和生长季节关键时期对比研究了川西高寒森林溪流和森林林下土壤中微生物群落的动态特征。研究结果发现,高寒森林溪流具有较低的真菌和细菌群落丰度;与森林土壤相同,溪流在冻融季节表现出相对生长季节更高的真菌/细菌比,而且从冻融季节到生长季节,溪流微生物丰度动态也表现出明显的季节性变化特征。与森林土壤不同的是,溪流中细菌和真菌的丰度及其Shannon-Wiener多样性指数的最高值均出现在生长季节而不是冬季冻融季节,并且溪流中细菌丰度在季节性变化的不同时期具有显著差异(P0.05)。此外,森林土壤细菌类群以芽孢杆菌属(Bacillus sp.)比例相对较高,真菌类群则以格孢菌属(Pleosporales sp.)、曲霉属(Aspergillus sp.)和其他一些子囊菌门(Ascomycota)的类群为优势;而溪流细菌类群以红球菌属(Rhodococcus sp.)为主,真菌类群则以曲霉属和空团菌属(Cenococcum sp.)为主。同时,季节性变化中温度、p H、水溶性有机碳和溶解氧等环境因子可显著影响溪流微生物群落结构及其组成,这些环境因子在高寒森林溪流微生物群落的季节性变化过程中具有重要的作用。  相似文献   
6.
Ecological, morphological and life‐history traits have been increasingly used in community ecology during the last decade. Dung beetles represent a model group of insects frequently used in studies of landscape ecology and grassland management. Their body sizes and nesting behavioral traits are regularly used to help understand ecological processes at the community level. However, information on their seasonal activity, wing morphometry and dung specialization is sparse in published reports, or is simply not available yet. We thus compiled a comprehensive list of the morphological and ecological traits of Central European dung beetles (Geotrupidae, Scarabaeidae and Aphodiidae). We gathered information from published works and, for the first time, took morphometric measurements of wings. We provide a database of 12 traits for all 100 dung beetle species occurring in Central Europe. Most species are not restricted to one specific dung type, and the most frequently used dung types are sheep/goat, cattle and horse dung, which are almost equally exploited by 90, 89 and 87 species, respectively. More than one‐third of all species are active in winter, and the number of active species is the highest in June. The wing morphometry shows a high variation and is largely determined by the family identity; the ratio of elytron length to wing area is the largest in Aphodiidae but the smallest in Geotrupidae. Our database is the first standardized set of information for Central European dung beetles and can be used in future trait‐based studies focusing on the ecology and conservation of these beetles.  相似文献   
7.
Abstract

A study was undertaken to compare the patterns of spatial variability, epiphytic percentage cover, and distribution of epiphytic fauna and flora between the two adjacent seagrasses Cymodocea nodosa and the invasive species Halophila stipulucea. Samples were taken at six stations separated by 600?m and exposed to different current conditions. The stations G2 and G5 were affected by a high current tide, while G4 was directly exposed to the northern marine currents. The station G3 was situated in the middle of a Posidonia oceanica bed and was less exposed to hydrodynamism, whereas the other stations were relatively protected. Results indicate that for both H. stipulacea and C. nodosa, shoot density and epiphytic cover biomass decreased when exposed to high levels of hydrodynamic activity. In terms of epiphytic leaf assemblages, our results showed significant differences for the two host plants in their mean cover and for the six stations at the largest and smallest spatial scale. Our observations highlight the dominance of Rhodophyta and the low number of epiphytic species and the epiphytic cover on H. stipulacea compared to C. nodosa. In addition, results indicate the absence of two taxa Hydrozoans and Annelida in the epiphytic assemblage of H. stipulacea leaves.  相似文献   
8.
9.
董思言  延晓冬  熊喆  石英  王娟怀 《生态学报》2015,35(14):4871-4879
近几十年中国地区土地利用/覆盖变化(LUCC)较大,在区域气候模拟中尤其需要使用更加准确的土地利用/覆盖数据。基于模式原有的USGS和新开发的LUC90两种土地利用/覆盖资料,利用区域环境集成模拟系统(RIEMS2.0)分别进行连续10a模拟,分析LUCC对中国不同季节气温的影响。结果表明:1)采用LUC90资料后,中国及东北、华北、华南夏季平均气温增加,但只有东北模拟与观测值的偏差减小,且通过显著性检验(P0.01)。中国及东北、华南冬季平均气温增加,并且模拟与观测值的偏差减少。中国及华北和华南对冬季气温年际变率的模拟改善好于夏季。2)土地利用/覆盖变化通过影响潜热通量的变化和净吸收辐射通量的变化来影响不同季节气温的变化。冬季净辐射通量变化对气温变化的贡献较夏季大,而夏季潜热通量变化对气温变化的贡献较冬季大。雨养农田转变森林、草地、灌溉农田过程造成通量变化,其对气温变化的影响也存在不同分区季节的差异。  相似文献   
10.
巢湖流域地下水硝态氮含量空间分布和季节变化格局   总被引:4,自引:0,他引:4  
王庆锁  顾颖  孙东宝 《生态学报》2014,34(15):4372-4379
2009年冬季、2010年春季和夏季分别在巢湖流域采集了253个、249个和230个水井的地下水样品,分析了其硝态氮含量。结果表明,巢湖流域的地下水硝酸盐污染比较严重,冬季、春季和夏季的地下水硝态氮的超标率(≥10 mg/L)均超过20%。巢湖北部区的地下水硝态氮含量高于南部地区。在巢湖北部区,东北部江淮分水岭丘陵区的地下水硝态氮含量较低。在巢湖南部区,地下水硝态氮含量具有从西部山区向东部平原逐渐升高的趋势。不同土地利用类型的地下水硝态氮含量排序是村庄菜地旱地乡镇水稻-油菜(或小麦)轮作田果园单季水稻田养殖场,传统水稻田绿色水稻田。巢湖流域地下水硝态氮含量的季节变化总趋势为冬季≈春季夏季,主要与降水有关。不同土地利用类型的地下水硝态氮含量的季节变化格局不同,其中地下水硝态氮含量呈现冬季春季夏季的土地类型为菜地、果园和水稻田,春季冬季夏季的土地类型为旱地、乡镇、畜禽养殖场,春季夏季冬季的土地类型为村庄,这种季节变化格局主要与不同土地利用类型的施肥量、施肥时间的不同有关。  相似文献   
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