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971.
Dumonteil E Ruiz-Piña H Rodriguez-Félix E Barrera-Pérez M Ramirez-Sierra MJ Rabinovich JE Menu F 《Memórias do Instituto Oswaldo Cruz》2004,99(3):253-256
In most countries, Chagas disease transmission control remains based on domestic insecticide application. We thus evaluated the efficacy of intra-domicile cyfluthrin spraying for the control of Triatoma dimidiata, the only Chagas disease vector in the Yucatán peninsula, Mexico, and monitored potential re-infestation every 15 days for up to 9 months. We found that there was a re-infestation of houses by adult bugs starting 4 months after insecticide application, possibly from sylvatic/peridomicile areas. This points out the need to take into account the potential dispersal of sylvatic/peridomestic adult bugs into the domiciles as well as continuity action for an effective vector control. 相似文献
972.
Andersen T Carstensen J Hernández-García E Duarte CM 《Trends in ecology & evolution》2009,24(1):49-57
There is an apparent gap between the prominence of present theoretical frameworks involving ecological thresholds and regime shifts, and the paucity of efforts to conduct simple tests and quantitative inferences on the actual appearance of such phenomena in ecological data. A wide range of statistical methods and analytical techniques are now available that render these questions tractable, some of them even dating back half a century. Yet, their application has been sparse and confined within a narrow subset of cases of ecological regime shifts. Our objective is to raise awareness on the range of techniques available, and to their principles and limitations, to promote a more operational approach to the identification of ecological thresholds and regime shifts. 相似文献
973.
Nebyl prokázán sensibilizující ú?inek EDTA na muta?ní aktivitu EMS uArabidopsis thaliana. 相似文献
974.
Qian Jia HongTao Wu XingJun Zhou Jian Gao Wei Zhao JouDi Aziz JingShuang Wei Lihua Hou Shuyin Wu Ying Zhang XiangFeng Dong YanMin Huang WeiYuan Jin HongJie Zhu XinHui Zhao ChunHua Huang LiPing Xing Liwen Li Jun Ma Xiyan Liu Ran Tao ShuaiDong Ye YiGao Song LingLing Song GuanPing Chen ChunLing Du XueTing Zhang Bo Li YanTao Wang Wei Yang Gilbert Rishton YuYang Teng GouQing Leng LuanFeng Li WenXian Liu LiJun Cheng QiuBo Liang ZhengWu Li XiuQin Zhang Yajun Zuo Wei Chen Huicheng Li Matthew Hui 《中国科学:生命科学英文版》2010,53(1):94-100
High mammalian gene expression was obtained for more than twenty different proteins in different cell types by just a few laboratory scale stable gene transfections for each protein. The stable expression vectors were constructed by inserting a naturally-occurring 1.006 kb or a synthetic 0.733 kb DNA fragment (including intron) of extremely GC-rich at the 5′ or/and 3′ flanking regions of these protein genes or their gene promoters. This experiment is the first experimental evidence showing that a non-coding extremely GC-rich DNA fragment is a super “chromatin opening element” and plays an important role in mammalian gene expression. This experiment has further indicated that chromatin-based regulation of mammalian gene expression is at least partially embedded in DNA primary structure, namely DNA GC-content. 相似文献
975.
María?F.?MonteroEmail author Manuela?Aristizábal Guillermo?García Reina 《Journal of applied phycology》2011,23(6):1053-1057
Biodiesel from algae is considered an alternative for a third generation of biofuels. However, most microalgae are not lipogenic
during fast growth periods, but high-lipid content occurs at resting stages. Microalgae biomass production for biodiesel needs
continuous high volumetric and aerial yields and large amount of neutral lipid in the biomass. These requirements are similar
to demanding a marathon runner to be obese. We show that by using cell sorting capabilities of flow cytometers, in combination
with the lipid-soluble fluorescent dye Nile Red, we can isolate and select cells with a high and stable lipid content. In
our study, we were able to select the equivalent of a stable “fat marathon runner” through three sorting events obtained from
wild populations of Tetraselmis suecica. 相似文献
976.
Spatial variation in twelve floral characters was examined in an epiphytic orchidLepanthes rupestris to evaluate the strength and direction of phenotypic selection in seven riparian populations along two river basins in the Caribbean National Forest “El Yunque” for a range of 18–34 months. We evaluated selection on floral characters based on male (pollinaria removal) and female fitness (fruit set). Simple linear and quadratic regressions were used to evaluate the strength of directional, disruptive and stabilizing selections. Univariate and multivariate analyses were used to estimate the total strength of the selection acting on a character. Phenotypic selection was inconsistent among characters and populations. Few of the characters appeared to be under selection and none of them was found to be consistent throughout all populations. Inconsistency in selection coefficients among populations could suggest that selection is spatially variable. We only noted one character (column length) which had some consistency in differential selection coefficients among populations. Previous studies have shown that effective population sizes inL. rupestris are small and the observed “fitness differences” among populations could as easily be explained as stochastic events at play. We argue that the observed “fitness differences” in most characters and inconsistency among populations are likely from stochastic noise and not phenotypic selection. Consequently, we propose that random selection on character state support the hypothesis of genetic drift in small orchid populations. 相似文献
977.
Graça Soveral Catarina Prista Teresa F. Moura Maria C. Loureiro‐Dias 《Biology of the cell / under the auspices of the European Cell Biology Organization》2011,103(1):35-54
In yeast, the presence of orthodox aquaporins has been first recognized in Saccharomyces cerevisiae, in which two genes (AQY1 and AQY2) were shown to be related to mammal and plant water channels. The present review summarizes the putative orthodox aquaporin protein sequences found in available genomes of yeast and filamentous fungi. Among the 28 yeast genomes sequenced, most species present only one orthodox aquaporin, and no aquaporins were found in eight yeast species. Alignment of amino acid sequences reveals a very diverse group. Similarity values vary from 99% among species within the Saccharomyces genus to 34% between ScAqy1 and the aquaporin from Debaryomyces hansenii. All of the fungal aquaporins possess the known characteristic sequences, and residues involved in the water channel pore are highly conserved. Advances in the establishment of the structure are reviewed in relation to the mechanisms of selectivity, conductance and gating. In particular, the involvement of the protein cytosolic N‐terminus as a channel blocker preventing water flow is addressed. Methodologies used in the evaluation of aquaporin activity frequently involve the measurement of fast volume changes. Particular attention is paid to data analysis to obtain accurate membrane water permeability parameters. Although the presence of aquaporins clearly enhances membrane water permeability, the relevance of these ubiquitous water channels in yeast performance remains obscure. 相似文献
978.
高速逆流色谱法分离纯化茶黄素 总被引:21,自引:0,他引:21
首次应用高速逆流色谱法分离纯化茶黄素单体成分,溶剂系统为乙酸乙酯-正己烷-甲醇-水(3:1:1:6),优化了分离茶黄素的条件。同时与SephadexLH-20柱色谱法梯度洗脱对比,结果表明,高速逆流色谱法分离时间相对较短,可进行较大量的分离制备。高速逆流色谱法较之SephadexLH-20柱色谱法还有一个突出的优点,即无不可逆吸附污染及不会导致样品化学变性。 相似文献
979.
Plants harbor diverse communities of fungi and other microorganisms. Fungi are known to occur both on plant surfaces (epiphytes)
and inside plant tissues (endophytes), but the two communities have rarely been compared. We compared epiphytic and endophytic
fungal communities associated with leaves of coffee (Coffea arabica) in Puerto Rico. We asked whether the dominant fungi are the same in both communities, whether endophyte and epiphyte communities
are equally diverse, and whether epiphytes and endophytes exhibit similar patterns of spatial heterogeneity among sites. Leaves
of naturalized coffee plants were collected from six sites in Puerto Rico. Epiphytic and endophytic fungi were isolated by
placing leaf pieces on potato dextrose agar without and with surface sterilization, respectively. A total of 821 colonies
were isolated and grouped into 131 morphospecies. The taxonomic affinities of the four most common nonsporulating fungi were
determined by sequencing the nuclear ribosomal internal transcribed spacer (ITS) region: two grouped with Xylaria and one each with Botryosphaeria and Guignardia. Of the most common genera, Pestalotia and Botryosphaeria were significantly more common as epiphytes; Colletotrichum, Xylaria, and Guignardia were significantly more common as endophytes. Suprisingly, more morphospecies occurred as endophytes than as epiphytes. Differences
among sites in number of fungi per plant were significant. Thus epiphytic and endophytic communities differed greatly on a
single leaf, despite living only millimeters apart, and both communities differed from site to site. Significant correlations
between occurrence of fungal morphospecies suggested that fungi may have positive or negative effects on their neighbors.
This is the first quantitative comparison of epiphytic and endophytic fungal floras in any plant, and the first to examine
endophytic fungi or epiphytic fungi in leaves of coffee, one of the world’s most valuable crops. 相似文献
980.
Bone marrow stromal cells produce nerve growth factor and glial cell line-derived neurotrophic factors 总被引:19,自引:0,他引:19
García R Aguiar J Alberti E de la Cuétara K Pavón N 《Biochemical and biophysical research communications》2004,316(3):753-754
Bone marrow stromal cells (BMSC) have attracted interest through their possible use for cell therapy in neurological diseases. Recent reports demonstrated that these cells are able to migrate and have potential for neuronal differentiation after transplantation into brain parenchyma. The objective of this work was determine whether rat BMSC express NGF and GDNF, in order to study its potential application for treatment of neurodegenerative diseases. BMSC were harvested from male rats and cultured in DMEM supplemented with 20% fetal bovine serum. At passage 6 the total RNA was isolated using TriZol reactive. RT-PCRs to evaluate the expression of NGF and GDNF using specific primers were carried out. Our results indicate that rat BMSC have potential to produce NGF and GDNF. We have not found any report in favor of GDNF or NGF production from rat BMSC. 相似文献