全文获取类型
收费全文 | 2782篇 |
免费 | 245篇 |
出版年
2023年 | 13篇 |
2022年 | 31篇 |
2021年 | 45篇 |
2020年 | 23篇 |
2019年 | 31篇 |
2018年 | 43篇 |
2017年 | 38篇 |
2016年 | 67篇 |
2015年 | 96篇 |
2014年 | 146篇 |
2013年 | 134篇 |
2012年 | 162篇 |
2011年 | 196篇 |
2010年 | 137篇 |
2009年 | 116篇 |
2008年 | 145篇 |
2007年 | 149篇 |
2006年 | 152篇 |
2005年 | 106篇 |
2004年 | 149篇 |
2003年 | 132篇 |
2002年 | 128篇 |
2001年 | 59篇 |
2000年 | 56篇 |
1999年 | 53篇 |
1998年 | 42篇 |
1997年 | 32篇 |
1996年 | 34篇 |
1995年 | 15篇 |
1994年 | 24篇 |
1993年 | 25篇 |
1992年 | 39篇 |
1991年 | 27篇 |
1990年 | 31篇 |
1989年 | 30篇 |
1988年 | 27篇 |
1987年 | 19篇 |
1986年 | 27篇 |
1985年 | 28篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1982年 | 17篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 24篇 |
1978年 | 20篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1972年 | 11篇 |
1971年 | 6篇 |
排序方式: 共有3027条查询结果,搜索用时 140 毫秒
1.
2.
3.
Yi-Shiang Huang Virginie Bertrand Dimitriya Bozukova Christophe Pagnoulle Christine Labrugère Edwin De Pauw Marie-Claire De Pauw-Gillet Marie-Christine Durrieu 《PloS one》2014,9(12)
Posterior Capsular Opacification (PCO) is the capsule fibrosis developed on implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LECs) undergoing Epithelial Mesenchymal Transition (EMT). Literature has shown that the incidence of PCO is multifactorial including the patient''s age or disease, surgical technique, and IOL design and material. Reports comparing hydrophilic and hydrophobic acrylic IOLs have shown that the former has more severe PCO. On the other hand, we have previously demonstrated that the adhesion of LECs is favored on hydrophobic compared to hydrophilic materials. By combining these two facts and contemporary knowledge in PCO development via the EMT pathway, we propose a biomimetically inspired strategy to promote LEC adhesion without de-differentiation to reduce the risk of PCO development. By surface grafting of a cell adhesion molecule (RGD peptide) onto the conventional hydrophilic acrylic IOL material, the surface-functionalized IOL can be used to reconstitute a capsule-LEC-IOL sandwich structure, which has been considered to prevent PCO formation in literature. Our results show that the innovative biomaterial improves LEC adhesion, while also exhibiting similar optical (light transmittance, optical bench) and mechanical (haptic compression force, IOL injection force) properties compared to the starting material. In addition, compared to the hydrophobic IOL material, our bioactive biomaterial exhibits similar abilities in LEC adhesion, morphology maintenance, and EMT biomarker expression, which is the crucial pathway to induce PCO. The in vitro assays suggest that this biomaterial has the potential to reduce the risk factor of PCO development. 相似文献
4.
5.
Bertrand Krafft 《Insectes Sociaux》1967,14(2):161-182
Résumé Le présent article a pour but d'analyser les multiples facteurs pouvant perturber l'étude duthermopreferendum de l'Araignée socialeAgelena consociata Denis et d'exposer les résultats obtenus.Pour satisfaire lethigmotactisme très développé de ces Araignées, la boîte servant à cette étude est cloisonnée et sa hauteur est de 1 cm.Un abreuvoir placé dans chaque compartiment maintient une humidité saturante pour compenser le gradient hygrométrique résultant du gradient thermique.L'expérience doit durer plusieurs jours et ne commencer que 24 heures après l'introduction des Araignées: premièrement, parce que cela permet aux Araignées de recouvrir le fond de la boîte d'une nappe de soie, ce qui contribue à les rapprocher de leurs conditions naturelles; deuxièmement, parce que la phase d'activité de ces Araignées est nocturne. Or, il semble que c'est lors de cette phase que les animaux choisissent leurthermopreferendum.Il ne faut pas effectuer plus de trois relevés par jour, sans quoi les Araignées, très sensibles aux perturbations, ont tendance à se diriger vers l'extrémité froide.Lethermopreferendum desAgelena consociata se situe à 22°65±0,10 pour la température de l'air et à 22°89±0,12 par rapport à la température du sol.
Summary This article aims at analysing the various causes which can disturb the study of thethermopreferendum of social SpidersAgelena consociata Denis and aims at explaining the achieved results.In order to satisfy the extremely developedthigmotactisme of these Spiders, the box used for that study has been partitioned off; its height is 1 cm.A small piece of wet cotton-wool placed into each partition maintains a saturated humidity to compensate the hygrometric gradient resulting from the thermic gradient.The experiment must go on during several days and must only begin a day after having put the Spiders into the box: first because the Spiders can cover the bottom with a cobweb, which contributes to create almost natural conditions; secondly because the period of activity of these Spiders takes place at night. As a fact it seems that it is during this period that the Spiders choose theirthermopreferendum.More than three readings a day must not be performed because otherwise the Spiders, wich are very sensitive to disturbances, are inclined to go towards the cold end of the box.Thethermopreferendum of theAgelena consociata takes place at 22°65 C±0,10 C as for the temperature of the air and at 22°89 C±0,12 C as for the temperature of the ground.相似文献
6.
A light-weight nonmagnetic, nonconductive instrument has been devised for use with magnetic resonance imaging, computerized tomography, and digital subtraction imaging for work in the field of epilepsy, brain tumors and vascular lesions. The apparatus' main characteristic is its ability to use optionally either the lateral orthogonal or the spherical-radial approach. 相似文献
7.
Barbara Tillmann Pierre Jolic?ur Masami Ishihara Nathalie Gosselin Olivier Bertrand Yves Rossetti Isabelle Peretz 《PloS one》2010,5(4)
Congenital amusia is a neurogenetic disorder of music processing that is currently ascribed to a deficit in pitch processing. A recent study challenges this view and claims the disorder might arise as a consequence of a general spatial-processing deficit. Here, we assessed spatial processing abilities in two independent samples of individuals with congenital amusia by using line bisection tasks (Experiment 1) and a mental rotation task (Experiment 2). Both amusics and controls showed the classical spatial effects on bisection performance and on mental rotation performance, and amusics and controls did not differ from each other. These results indicate that the neurocognitive impairment of congenital amusia does not affect the processing of space. 相似文献
8.
Effect of dibutyryl cyclic AMP and theophylline on lipoprotein lipase secretion by human monocyte-derived macrophages 总被引:1,自引:0,他引:1
The effect of dibutyryl cyclic AMP and theophylline on lipoprotein lipase secretion was investigated after a 24 h pretreatment of human monocyte-derived macrophages. Both the effectors decreased in a dose-dependent manner the enzyme activity recovered in the culture medium. The decrease in lipoprotein lipase activity appeared to be related to reduced enzyme synthesis without apparent modification of its stability and half-life and was conversely associated with an increase of lysosomal acid hydrolase activities. This effect was reversible on removal of the nucleotide. The present findings suggest that cyclic AMP may play a role in lipoprotein lipase expression in human macrophages and therefore may participate in the regulation of lipoprotein uptake by these cells, which are strongly implicated in the atherogenic process. 相似文献
9.
Quantification by fluorescence of apurinic sites in DNA 总被引:1,自引:0,他引:1
J R Bertrand C Malvy C Paoletti 《Biochemical and biophysical research communications》1987,143(2):768-774
Time dependent fluorescence is observed when single or double stranded DNA with apurinic sites are mixed with 9-NH2-ellipticine. A concentration dependent plateau is obtained which is linearly related to the ratio of apurinic sites in DNA. We therefore suggest that it is possible to have a direct measurement of apurinic sites in DNA by fluorescence. 相似文献
10.
alpha-DNA. VI: Comparative study of alpha- and beta-anomeric oligodeoxyribonucleotides in hybridization to mRNA and in cell free translation inhibition. 总被引:18,自引:15,他引:3
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C Gagnor J R Bertrand S Thenet M Lema?tre F Morvan B Rayner C Malvy B Lebleu J L Imbach C Paoletti 《Nucleic acids research》1987,15(24):10419-10436
alpha and beta-anomeric d(G2T12G2) oligodeoxyribonucleotides were compared for their hybridization to rA12: the observed melting temperatures are 27 degrees C for beta-oligodeoxyribonucleotide/RNA hybrid and 53 degrees C for alpha-oligodeoxyribonucleotide/RNA. alpha-oligonucleotides with the four bases, complementary to natural mRNAs, were synthesized for the first time, labeled at their 5'-end with [32P] and used as probes in Northern blot experiments. In spite of these higher affinities for their target RNA's, they were unable to block translation of natural or synthetic mRNA's in rabbit reticulocyte lysate. We have studied the RNase H activity on model rA12:alpha- or beta-d(G2T12G2) hybrids or on mRNA:alpha- or beta-oligonucleotides hybrids. Specific hybridization protects RNA strech when using alpha-oligonucleotides but not beta-oligonucleotides. Thus, our results show the inability of RNase H to degrade RNA in alpha-oligodeoxyribonucleotides:RNA duplexes. 相似文献