全文获取类型
收费全文 | 5375篇 |
免费 | 478篇 |
国内免费 | 3篇 |
专业分类
5856篇 |
出版年
2023年 | 24篇 |
2022年 | 52篇 |
2021年 | 103篇 |
2020年 | 65篇 |
2019年 | 51篇 |
2018年 | 79篇 |
2017年 | 71篇 |
2016年 | 128篇 |
2015年 | 242篇 |
2014年 | 276篇 |
2013年 | 347篇 |
2012年 | 441篇 |
2011年 | 449篇 |
2010年 | 286篇 |
2009年 | 269篇 |
2008年 | 338篇 |
2007年 | 367篇 |
2006年 | 363篇 |
2005年 | 349篇 |
2004年 | 309篇 |
2003年 | 347篇 |
2002年 | 303篇 |
2001年 | 50篇 |
2000年 | 33篇 |
1999年 | 58篇 |
1998年 | 73篇 |
1997年 | 43篇 |
1996年 | 43篇 |
1995年 | 32篇 |
1994年 | 34篇 |
1993年 | 29篇 |
1992年 | 29篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1974年 | 5篇 |
1973年 | 8篇 |
1972年 | 5篇 |
1971年 | 5篇 |
排序方式: 共有5856条查询结果,搜索用时 15 毫秒
71.
72.
Julie Landes Pierre‐Yves Henry Isabelle Hardy Martine Perret Samuel Pavard 《Ecology and evolution》2019,9(11):6189-6198
The survival cost of reproduction has been revealed in many free‐ranging vertebrates. However, recent studies on captive populations failed to detect this cost. Theoretically, this lack of survival/reproduction trade‐off is expected when resources are not limiting, but these studies may have failed to detect the cost, as they may not have fully accounted for potential confounding effects, in particular interindividual heterogeneity. Here, we investigated the effects of current and past reproductive effort on later survival in captive females of a small primate, the gray mouse lemur. Survival analyses showed no cost of reproduction in females; and the pattern was even in the opposite direction: the higher the reproductive effort, the higher the chances of survival until the next reproductive event. These conclusions hold even while accounting for interindividual heterogeneity. In agreement with aforementioned studies on captive vertebrates, these results remind us that reproduction is expected to be traded against body maintenance and the survival prospect only when resources are so limiting that they induce an allocation trade‐off. Thus, the cost of reproduction has a major extrinsic component driven by environmental conditions. 相似文献
73.
Kang S Bennett CN Gerin I Rapp LA Hankenson KD Macdougald OA 《The Journal of biological chemistry》2007,282(19):14515-14524
74.
Aneuploidy, the relative excess or deficiency of specific chromosome types, results in gene dosage imbalance. Plants can produce viable and fertile aneuploid individuals, while most animal aneuploids are inviable or developmentally abnormal. The swarms of aneuploid progeny produced by Arabidopsis triploids constitute an excellent model to investigate the mechanisms governing dosage sensitivity and aneuploid syndromes. Indeed, genotype alters the frequency of aneuploid types within these swarms. Recombinant inbred lines that were derived from a triploid hybrid segregated into diploid and tetraploid individuals. In these recombinant inbred lines, a single locus, which we call SENSITIVE TO DOSAGE IMBALANCE (SDI), exhibited segregation distortion in the tetraploid subpopulation only. Recent progress in quantitative genotyping now allows molecular karyotyping and genetic analysis of aneuploid populations. In this study, we investigated the causes of the ploidy-specific distortion at SDI. Allele frequency was distorted in the aneuploid swarms produced by the triploid hybrid. We developed a simple quantitative measure for aneuploidy lethality and using this measure demonstrated that distortion was greatest in the aneuploids facing the strongest viability selection. When triploids were crossed to euploids, the progeny, which lack severe aneuploids, exhibited no distortion at SDI. Genetic characterization of SDI in the aneuploid swarm identified a mechanism governing aneuploid survival, perhaps by buffering the effects of dosage imbalance. As such, SDI could increase the likelihood of retaining genomic rearrangements such as segmental duplications. Additionally, in species where triploids are fertile, aneuploid survival would facilitate gene flow between diploid and tetraploid populations via a triploid bridge and prevent polyploid speciation. Our results demonstrate that positional cloning of loci affecting traits in populations containing ploidy and chromosome number variants is now feasible using quantitative genotyping approaches. 相似文献
75.
Sourisseau M Schilte C Casartelli N Trouillet C Guivel-Benhassine F Rudnicka D Sol-Foulon N Le Roux K Prevost MC Fsihi H Frenkiel MP Blanchet F Afonso PV Ceccaldi PE Ozden S Gessain A Schuffenecker I Verhasselt B Zamborlini A Saïb A Rey FA Arenzana-Seisdedos F Desprès P Michault A Albert ML Schwartz O 《PLoS pathogens》2007,3(6):e89
An unprecedented epidemic of chikungunya virus (CHIKV) infection recently started in countries of the Indian Ocean area, causing an acute and painful syndrome with strong fever, asthenia, skin rash, polyarthritis, and lethal cases of encephalitis. The basis for chikungunya disease and the tropism of CHIKV remain unknown. Here, we describe the replication characteristics of recent clinical CHIKV strains. Human epithelial and endothelial cells, primary fibroblasts and, to a lesser extent, monocyte-derived macrophages, were susceptible to infection and allowed viral production. In contrast, CHIKV did not replicate in lymphoid and monocytoid cell lines, primary lymphocytes and monocytes, or monocyte-derived dendritic cells. CHIKV replication was cytopathic and associated with an induction of apoptosis in infected cells. Chloroquine, bafilomycin-A1, and short hairpin RNAs against dynamin-2 inhibited viral production, indicating that viral entry occurs through pH-dependent endocytosis. CHIKV was highly sensitive to the antiviral activity of type I and II interferons. These results provide a general insight into the interaction between CHIKV and its mammalian host. 相似文献
76.
Comparative proteome profiling and functional analysis of chronic myelogenous leukemia cell lines 总被引:1,自引:0,他引:1
Fontana S Alessandro R Barranca M Giordano M Corrado C Zanella-Cleon I Becchi M Kohn EC De Leo G 《Journal of proteome research》2007,6(11):4330-4342
The aim of the present study was the molecular profiling of different Ph+ chronic myelogenous leukemia (CML) cell lines (LAMA84, K562, and KCL22) by a proteomic approach. By employing two-dimensional gel electrophoresis combined with mass spectrometry analysis, we have identified 191 protein spots corresponding to 142 different proteins. Among these, 63% were cancer-related proteins and 74% were described for the first time in leukemia cells. Multivariate analysis highlighted significant differences in the global proteomic profile of the three CML cell lines. In particular, the detailed analysis of 35 differentially expressed proteins revealed that LAMA84 cells preferentially expressed proteins associated with an invasive behavior, while K562 and KCL22 cells preferentially expressed proteins involved in drug resistance. These data demonstrate that these CML cell lines, although representing the same pathological phenotype, show characteristics in their protein expression profile that suggest different phenotypic leukemia subclasses. These data contribute a new potential characterization of the CML phenotype and may help to understand interpatient variability in the progression of disease and in the efficacy of a treatment. 相似文献
77.
A comparative analysis of perturbations caused by a gene knock-out, a dominant negative allele, and a set of peptide aptamers 总被引:1,自引:0,他引:1
78.
79.
Sophie Vanhunsel Steven Bergmans An Beckers Isabelle Etienne Tine Van
Bergen Lies De Groef Lieve Moons 《Aging cell》2022,21(1)
As the mammalian central nervous system matures, its regenerative ability decreases, leading to incomplete or non‐recovery from the neurodegenerative diseases and central nervous system insults that we are increasingly facing in our aging world population. Current neuroregenerative research is largely directed toward identifying the molecular and cellular players that underlie central nervous system repair, yet it repeatedly ignores the aging context in which many of these diseases appear. Using an optic nerve crush model in a novel biogerontology model, that is, the short‐living African turquoise killifish, the impact of aging on injury‐induced optic nerve repair was investigated. This work reveals an age‐related decline in axonal regeneration in female killifish, with different phases of the repair process being affected depending on the age. Interestingly, as in mammals, both a reduced intrinsic growth potential and a non‐supportive cellular environment seem to lie at the basis of this impairment. Overall, we introduce the killifish visual system and its age‐dependent regenerative ability as a model to identify new targets for neurorepair in non‐regenerating individuals, thereby also considering the effects of aging on neurorepair. 相似文献
80.