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61.
62.
Diversity of an ectomycorrhizal fungal community studied by a root tip and total soil DNA approach 总被引:4,自引:0,他引:4
Molecular methods based on soil DNA extracts are increasingly being used to study the fungal diversity of ectomycorrhizal (EM) fungal communities in soil. Contrary to EM root tip identification, the use of molecular methods enables identification of extramatrical mycelia in soil. To compare fungal diversity as determined by root tip identification and mycelial identification, six soil samples were analysed. Root tips were extracted from the six samples and after amplification, the basidiomycete diversity on the root tips was analysed by denaturing gradient gel electrophoresis (DGGE). The soil from the six samples was sieved, total soil DNA was extracted and after amplification, the basidiomycete diversity in the soil fractions was analysed by DGGE. Fourteen different bands were excised from the DGGE gel and sequenced; fungal taxon names could be assigned to eight bands. Out of a total of 14 fungal taxa detected in soil, 11 fungal taxa were found on root tips, of which seven were EM fungal taxa. To examine whether the sieving treatment would affect EM species diversity, two different sieve mesh sizes were used and in addition, the organic soil fraction was analysed separately. DGGE analysis showed no differences in banding pattern for the different soil fractions. The organic fraction gave the highest DGGE band intensities. This work demonstrates that there is a high correspondence between basidiomycete diversity detected by molecular analysis of root tips and soil samples, irrespective of the soil fraction being analysed. 相似文献
63.
Using ethane as a marker for peroxidative damage to membranes by reactive oxygen species (ROS) we examined the injury of rice
seedlings during submergence in the dark. It is often expressed that membrane injury from ROS is a post-submergence phenomenon
occurring when oxygen is re-introduced after submergence-induced anoxia. We found that ethane production, from rice seedlings
submerged for 24–72 h, was stimulated to 4–37 nl gFW−1, indicating underwater membrane peroxidation. When examined a week later the seedlings were damaged or had died. On de-submergence
in air, ethane production rates rose sharply, but fell back to less than 0.1 nl gFW−1 h−1 after 2 h. We compared submergence-susceptible and submergence-tolerant cultivars, submergence starting in the morning (more
damage) and in the afternoon (less damage) and investigated different submergence durations. The seedlings showed extensive
fatality whenever total ethane emission exceeded about 15 nl gFW−1. Smaller amounts of ethane emission were linked to less extensive injury to leaves. Partial oxygen shortage (O2 levels <1%) imposed for 2 h in gas phase mixtures also stimulated ethane production. In contrast, seedlings under anaerobic
gas phase conditions produced no ethane until re-aerated: then a small peak was observed followed by a low, steady ethane
production. We conclude that damage during submergence is not associated with extensive anoxia. Instead, injury is linked
to membrane peroxidation in seedlings that are partially oxygen deficient while submerged. On return to air, further peroxidation
is suppressed within about 2 h indicating effective control of ROS production not evident during submergence itself. 相似文献
64.
We designed cassettes allowing the systematic fusion of fluorescent or luminescent proteins preceded by the calmodulin binding peptide tag to the C–terminus of Escherichia coli proteins. The chromosomal insertion, and thus physiological expression level of these fusions, permits the study of protein localization by fluorescent microscopy and protein quantification, in vivo and dynamically in diverse conditions. Furthermore, the calmodulin binding peptide tag allows standard detection, affinity purification, and co–purification experiments. These cassettes are therefore very valuable for the versatility of experiments they make available for a given strain, from biochemistry to dynamic and in vivo studies. 相似文献
65.
目的采用液相悬浮芯片系统同时测定实验兔圆小囊中IL-1β、IL-1R1、IL=8、IL-8RA和IL=15各基因的表达情况,并对该方法进行评价。方法利用Affymetrix的Panomics QuantiGene Plex2.0Assay中bDNA信号放大和多磁珠分析技术,来同时检测两种实验兔圆小囊中多重mRNA并定量。建立实验兔免疫相关白介素基因的液相悬浮芯片检测方法。结果可同时检测IL-1β、IL=1R1、IL-8、IL=8RA和IL-15各基因的含量,并发现WHBE兔IL-15基因的相对表达量显著高于JW兔(P〈0.05),IL-1R1基因的相对表达量显著高于JW兔(P〈0.01),IL-8RA基因在WHBE兔中的相对表达量也高于JW兔(P〈0.05)。结论建立了实验兔白介素基因的液相悬浮芯片检测方法,WHBE兔的IL-15、IL-1R1和IL-8RA基因表达量较高,可能与WHBE兔独特的免疫学特性有关。 相似文献
66.
Simulations inform design of regional occupancy‐based monitoring for a sparsely distributed,territorial species 下载免费PDF全文
Quresh S. Latif Martha M. Ellis Victoria A. Saab Kim Mellen‐McLean 《Ecology and evolution》2018,8(2):1171-1185
Sparsely distributed species attract conservation concern, but insufficient information on population trends challenges conservation and funding prioritization. Occupancy‐based monitoring is attractive for these species, but appropriate sampling design and inference depend on particulars of the study system. We employed spatially explicit simulations to identify minimum levels of sampling effort for a regional occupancy monitoring study design, using white‐headed woodpeckers (Picoides albolvartus), a sparsely distributed, territorial species threatened by habitat decline and degradation, as a case study. We compared the original design with commonly proposed alternatives with varying targets of inference (i.e., species range, space use, or abundance) and spatial extent of sampling. Sampling effort needed to achieve adequate power to observe a long‐term population trend (≥80% chance to observe a 2% yearly decline over 20 years) with the previously used study design consisted of annually monitoring ≥120 transects using a single‐survey approach or ≥90 transects surveyed twice per year using a repeat‐survey approach. Designs that shifted inference toward finer‐resolution trends in abundance and extended the spatial extent of sampling by shortening transects, employing a single‐survey approach to monitoring, and incorporating a panel design (33% of units surveyed per year) improved power and reduced error in estimating abundance trends. In contrast, efforts to monitor coarse‐scale trends in species range or space use with repeat surveys provided extremely limited statistical power. Synthesis and applications. Sampling resolutions that approximate home range size, spatially extensive sampling, and designs that target inference of abundance trends rather than range dynamics are probably best suited and most feasible for broad‐scale occupancy‐based monitoring of sparsely distributed territorial animal species. 相似文献
67.
68.
MicroRNAs简称miRNAs(微小RNAs),是真核生物、原核生物以及病毒中由非编码蛋白基因转录的初级microRNAs加工成的调控因子.在转录后水平和蛋白质翻译水平,microRNAs通过降解或翻译抑制甚至激活来调控靶mRNA.实验和计算机方法已应用于microRNAs和靶基因的鉴定.大规模测序技术使得microRNAs在不同物种的多样性分析得以实现.着重介绍microRNAs、靶基因及其功能研究的实验技术和计算机方法,以及基于microRNAs的保守性,借助模式生物中已知的microRNAs,研究其在其他生物中的功能和作用. 相似文献
69.
铜绿假单胞菌是临床上常见致病菌, 传统的检测方法有各种弊端。本研究对该细菌的ETA基因用生物信息学方法加以分析, 选取相对保守且高度特异的DNA序列, 设计一对特异性引物和一个TaqMan探针, 建立FQ-PCR (fluorescence quantitative PCR)检测PA的方法。通过对梯度浓度的铜绿假单胞菌基因组DNA样品进行FQ-PCR检测和对多种细菌的DNA进行扩增, 来检测其灵敏度和验证引物和探针的特异性。试验结果表明, 对比现有的检测方法, 以ETA基因为靶基因, 基于TaqMan探针的快速FQ-PCR检测技术有更高的灵敏度和更好的特异性等优点, 具有很好的研究价值和应用前景。 相似文献
70.
Detecting a smooth signal: Optimality of cusum based procedures 总被引:2,自引:0,他引:2