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51.
The basal anomodont Suminia getmanovi Ivakhnenko, 1994 from the late Palaeozoic of Russia is highly specialized in its masticatory apparatus, and has been suggested to represent the earliest arboreal tetrapod in the fossil record. Its postcranial anatomy is described in detail for the first time, revealing a large number of autapomorphies for this small herbivore. These include a reduced number of presacral and therein dorsal vertebrae, an elongate neck, a long and possibly prehensile tail, a procoracoid with a notch at its ventromedial margin rather than a foramen, an iliac blade with a robust ridge at its anteromedial edge, a pubis with a puboischiadic fenestra and separate pubic foramen, and elongate limbs. Additional autapomorphic characters are displayed in the autopodium, which comprises about 40% of the entire limb length. These features include an enlarged, phalangiform distal carpal 1 and tarsal 1, a short and robust first metacarpal, a crescent‐shaped distal tarsal 4, and elongate penultimate phalangeal elements. The phylogenetic relationships of basal anomodonts are revisited using an expanded data set, with the addition of key taxa and several postcranial characters. Unlike dicynodonts, Suminia retained the plesiomorphic phalangeal formula for amniotes of 2‐3‐4‐5‐3 (manus) and 2‐3‐4‐5‐4 (pes). This pattern is achieved by the retention of disc‐like phalangeal elements between the proximal and penultimate phalanges in digits III, IV (manus and pes), and V (pes only). In light of the new material, Suminia can be recognized as the most complete basal anomodont, offering new insights into the early evolution of the group. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 661–698.  相似文献   
52.
植物对铅胁迫的耐性及其解毒机制研究进展   总被引:18,自引:0,他引:18  
植物对重金属元素的耐性、积累特性是利用植物修复铅污染土壤的前提,因而需要全面理解植物对铅吸收、转运、积累和解毒的一系列生理机制.本文从植物自身对铅的适应和防御机制出发,综述了细胞壁和液泡在植物细胞钝化与铅积累中的功能;根系分泌物对铅生物有效性的影响;超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、谷光苷肽还原酶(GR)、抗坏血酸过氧化物酶(APX)和植物螯合肽、谷胱甘肽在铅解毒中的作用,以及金属硫蛋白和铅特异基因表达的研究进展.并对未来该领域的研究以及铅污染环境植物修复技术的发展进行了展望.  相似文献   
53.
生长期SD大鼠对日粮常规营养物质和氨基酸消化率的研究   总被引:2,自引:0,他引:2  
目的了解SD大鼠对营养物质消化特点,研究不同结构日粮营养物质的可消化性,为筛选适合SD生长大鼠的日粮营养物质水平和日粮配方提供科学参数. 方法采用饲养试验结束时的90 d龄体重相近的90只SD大鼠,分为9个组,每组10 只,雌雄各半,分笼、每笼5只,采用全收粪法对9个配方日粮进行5 d消化试验,测定9个日粮的能量和6种常规营养物质以及17种氨基酸(AA)的表观消化率.结果以第3组日粮的可消化性为最好,它的总能(GE)、粗蛋白(CP)、粗纤维(CF)、粗脂肪(EE)、无氮浸出物(NFE)、钙(Ca)、磷(P)和17种氨基酸的表观消化率(%)依次分别为85.7、88.0、2 9.5、89.2、90.0、47.6、35.7和85.0(17个氨基酸AA平均值);这些营养物质在9个组的总平均表现消化率(%)依次分别为82.1、79.1、24.7、84.9、88.4、37.1、33.1和 81.5,结果表明,生长期SD大鼠对不同结构的日粮,不同水平的营养物质的可消化性不同 ,不同营养物质的消化率差别较大,以第3组日粮配方及其营养水平较适宜于生长期SD大鼠 ,它的DE、CP、EE、CF、NFE、Ca和P水平依次为14MJ.kg-1、18%、4.5%、4.0%、5 5.0%、1.00%和0.66%,它的苏氨酸,胱氨酸、缬氨酸、蛋氨酸、异亮氨酸、亮氨酸、酪氨酸、苯丙氨酸、赖氨酸、组氨酸和精氨酸水(%)依次为0.74、0.38、1.00、0.40、0. 93、1.65、0.62、0.94、1.00、0.58和1.22,它的可消化氨基酸水平(%)依次为0.60 、0.29、0.84、0.31、0.76、1.45、0.52、0.82、0.87、0.52和1.12.结论日粮能量具有较高的可消化性,对于其他营养物质的消化吸收利用有正效应影响.  相似文献   
54.
1963-2012年新疆棉花需水量时空分布特征   总被引:3,自引:0,他引:3  
王梅  杨倩  郑江华  刘志辉 《生态学报》2016,36(13):4122-4130
研究基于新疆地区54个国家基本气象站1963-2012年的逐日气象资料,采用联合国粮食与农业组织FAO推荐的Penman-Monteith公式及作物系数法,计算了近50年来新疆棉花全育期和各生长阶段需水量。并利用线性趋势估计、MK检验、空间插值法对农作物全育期及各生长阶段需水量年际变化趋势和空间分布特征进行分析。结果表明:1)1963-2012年,新疆54个气象站棉花全育期平均需水量为759 mm,各站变化范围为555-1205 mm,差异明显。其空间分布整体呈现西北向东南递增、南疆大于北疆、东部大于西部的趋势。2)1963-2012年,在棉花的生长初期与发育期,全疆需水量空间分布总体由北向南增大并呈带状。在棉花的生长中期与生长末期,需水量空间分布表现为由西向东增大的格局。3)近50年棉花不同生长阶段需水量总体呈现下降趋势,并且除了生长中期下降趋势较显著外其他都不太明显。其中,生长中期下降速率最大为6.1 mm/10a,发育期及生长末期下降速率次之分别为2 mm/10a和1.3 mm/10a,生长初期下降速率最小,需水量以0.6 mm/10a的速率递减。4)新疆1963-2012年棉花全育期需水量总体呈下降趋势,递减速率平均约为5.3 mm/10a,并在1981年开始发生突变。5)全育期年需水量下降倾向率总体呈现与全育期平均需水量相同的空间分布特征,总体呈现北疆小于南疆、东部大于西部、由西北向东南递增的空间分布特征。  相似文献   
55.
We present a Bayesian method for characterizing the mating system of populations reproducing through a mixture of self-fertilization and random outcrossing. Our method uses patterns of genetic variation across the genome as a basis for inference about reproduction under pure hermaphroditism, gynodioecy, and a model developed to describe the self-fertilizing killifish Kryptolebias marmoratus. We extend the standard coalescence model to accommodate these mating systems, accounting explicitly for multilocus identity disequilibrium, inbreeding depression, and variation in fertility among mating types. We incorporate the Ewens sampling formula (ESF) under the infinite-alleles model of mutation to obtain a novel expression for the likelihood of mating system parameters. Our Markov chain Monte Carlo (MCMC) algorithm assigns locus-specific mutation rates, drawn from a common mutation rate distribution that is itself estimated from the data using a Dirichlet process prior model. Our sampler is designed to accommodate additional information, including observations pertaining to the sex ratio, the intensity of inbreeding depression, and other aspects of reproduction. It can provide joint posterior distributions for the population-wide proportion of uniparental individuals, locus-specific mutation rates, and the number of generations since the most recent outcrossing event for each sampled individual. Further, estimation of all basic parameters of a given model permits estimation of functions of those parameters, including the proportion of the gene pool contributed by each sex and relative effective numbers.  相似文献   
56.
Ecological models written in a mathematical language L(M) or model language, with a given style or methodology can be considered as a text. It is possible to apply statistical linguistic laws and the experimental results demonstrate that the behaviour of a mathematical model is the same of any literary text of any natural language. A text has the following characteristics: (a) the variables, its transformed functions and parameters are the lexic units or LUN of ecological models; (b) the syllables are constituted by a LUN, or a chain of them, separated by operating or ordering LUNs; (c) the flow equations are words; and (d) the distribution of words (LUM and CLUN) according to their lengths is based on a Poisson distribution, the Chebanov's law. It is founded on Vakar's formula, that is calculated likewise the linguistic entropy for L(M). We will apply these ideas over practical examples using MARIOLA model. In this paper it will be studied the problem of the lengths of the simple lexic units composed lexic units and words of text models, expressing these lengths in number of the primitive symbols, and syllables. The use of these linguistic laws renders it possible to indicate the degree of information given by an ecological model.  相似文献   
57.
目的:探讨黄连解毒汤(HLJDT)对链脲佐菌素(STZ)诱导的2型糖尿病肾病大鼠肾脏的保护作用及其可能的机制。方法:将雄性Wistar大鼠随机分为对照组(n=10)和用STZ诱导的模型组。将成功造模的大鼠随机分为模型组(n=12)、低、中和高剂量组(每组n=12),分别给予对照组和模型组灌胃饮用水,而给其他三组分别灌胃HLJDT(60、120和240 g·kg-1·d-1)。12周后处死大鼠并测量生化指标,实时荧光定量PCR和western blot检测TGF-β1,p38MAPK和Caspase-3的基因和蛋白表达。结果:与模型组比较,HLJDT中高剂量组体重、肾脏重、肾重体重比和FBG显著提高。与对照组比较,模型组的TG、BUN、Scr和UP 24 h均显著提高;而与模型组比较,HLJDT高剂量组均显著降低TG、BUN、Scr、UP 24 h和MDA的水平,升高NO,SOD的水平。另外,TGF-β1,P38MAPK和Caspase-3的表达,模型组显著高于对照组,但经过HLJDT的治疗后,与模型组比较有显著降低。(所有取值为P0.05,P0.01)。结论:我们的研究提供了HLJDT是通过调控血糖、降低氧化应激的水平和下调TGF-β1,p38MAPK和Caspase-3的表达来保护DN大鼠的实验依据。  相似文献   
58.
A spin-labeled fatty acid (16-doxylstearic acid), linked by an ester bond to a maleimide or a nitrene residue, was covalently attached to band 3 of erythrocyte membranes. The electron spin resonance spectrum of the spin-labeled protein was examined at different temperatures in: (a) whole erythrocyte ghosts; (b) ghosts depleted of spectrin and actin; (c) alkaline-treated ghosts; (d) vesicles made with purified band 3 reassociated with dimyristoylphosphatidylcholine. Most spectra are composite with a major component corresponding to a large overall splitting. The determination of the percentage of the immobilized component was carried out by pairwise subtraction. At low temperatures (1–7°C), the highest fraction of immobilized component was found in dimyristoylphosphatidylcholine vesicles (approx. 100%); alkaline-treated membranes had approx. 75% of the immobilized component at the same temperature; whole erythrocyte, spectrin/actin-depleted and spectrin/actin/ankyrin-depleted ghosts gave identical results (approx. 60% of immobilized component). The immobilized fraction decreased in all samples with increasing temperature or addition of a nonsolubilizing concentration of dodecyl octaethylene glycol monoether. In dimyristoylphosphatidylcholine vesicles, however, the modification in the ratio of the two components was obtained only above the lipid transition temperature (23°C). The strong immobilization of the spin-labeled lipid chain at all temperatures suggested trapping of the lipid chain between proteins. At low temperature, in dimyristoylphosphatidylcholine vesicles or in alkaline-treated ghosts, lipid-protein segregation is likely to take place. In whole erythrocyte ghosts, on the other hand, the large contribution of the motionally restricted component at physiological temperature indicates the oligomeric nature of band 3. Partial dissociation of the oligomers occurs as the temperature is increased, but the presence or absence of cytoskeletal proteins has no influence on the state of oligomerization of band 3.  相似文献   
59.
Aims:  To determine the survival and growth characteristics of Cronobacter species ( Enterobacter sakazakii ) in infant wheat-based formulas reconstituted with water, milk, grape juice or apple juice during storage.
Methods and Results:  Infant wheat-based formulas were reconstituted with water, ultra high temperature milk, pasteurized grape or apple juices. The reconstituted formulas were inoculated with Cronobacter sakazakii and Cronobacter muytjensii and stored at 4, 25 or 37°C for up to 24 h. At 25 and 37°C, Cronobacter grew more (>5 log10) in formulas reconstituted with water or milk than those prepared with grape or apple juices ( c. 2–3 log10). The organism persisted, but did not grow in any formulas stored at 4°C. Formulas reconstituted with water and milk decreased from pH 6·0 to 4·8–5·0 after 24 h, whereas the pH of the formulas reconstituted with fruit juices remained at their initial pH values, c. pH 4·8–5·0.
Conclusions:  Cronobacter sakazakii and C. muytjensii can grow in reconstituted wheat-based formulas. If not immediately consumed, these formulas should be stored at refrigeration temperatures to reduce the risk of infant infection.
Significance and Impact of the Study:  The results of this study will be of use to regulatory agencies and infant formula producers to recommend storage conditions that reduce the growth of Cronobacter in infant wheat-based formulas.  相似文献   
60.
Aims:  To determine the prevalence of Cronobacter spp. ( Enterobacter sakazakii ) in follow-on formula powders commercially available in European countries.
Methods and Results:  A total of 470 samples comprising 31 different products from 18 brand names belonging to seven companies were tested for the presence of Cronobacter species. No milk- or soy-based infant formula powders were found to contain Cronobacter species . However, two cereal-based infant drinks were positive for Cronobacter sakazakii . A review of the published cases spanning the past 48 years did not reveal any fatalities attributable to Cronobacter spp. in children over 3 months.
Conclusions:  The low incidence of Cronobacter in infant powdered drinks, the lack of fatal Cronobacter infections in infants greater than 3 months and the low incidence of Cronobacter -related reported illness in this age group indicated that ingestion of these products presents a low risk for the intended consumers.
Significance and Impact of the Study:  The risk posed to neonates from the consumption of infant formula contaminated with Cronobacter is clear. Risks associated with powdered follow-on formulae intended for consumption by older infants is now under consideration by the World Health Organization. Our data contributes to the body of knowledge available for the assessment of the risk to consumers from these food products.  相似文献   
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