全文获取类型
收费全文 | 3585篇 |
免费 | 241篇 |
国内免费 | 5篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 52篇 |
2021年 | 84篇 |
2020年 | 37篇 |
2019年 | 59篇 |
2018年 | 90篇 |
2017年 | 63篇 |
2016年 | 110篇 |
2015年 | 166篇 |
2014年 | 189篇 |
2013年 | 240篇 |
2012年 | 295篇 |
2011年 | 327篇 |
2010年 | 202篇 |
2009年 | 162篇 |
2008年 | 228篇 |
2007年 | 254篇 |
2006年 | 253篇 |
2005年 | 236篇 |
2004年 | 208篇 |
2003年 | 165篇 |
2002年 | 194篇 |
2001年 | 21篇 |
2000年 | 7篇 |
1999年 | 18篇 |
1998年 | 28篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有3831条查询结果,搜索用时 18 毫秒
901.
Beth L. Nicholson Baodong Wu Irina Chevtchenko K. Andrew White 《RNA (New York, N.Y.)》2010,16(7):1402-1419
RNA viruses recruit the host translational machinery by different mechanisms that depend partly on the structure of their genomes. In this regard, the plus-strand RNA genomes of several different pathogenic plant viruses do not contain traditional translation-stimulating elements, i.e., a 5′-cap structure and a 3′-poly(A) tail, and instead rely on a 3′-cap-independent translational enhancer (3′CITE) located in their 3′ untranslated regions (UTRs) for efficient synthesis of viral proteins. We investigated the structure and function of the I-shaped class of 3′CITE in tombusviruses—also present in aureusviruses and carmoviruses—using biochemical and molecular approaches and we determined that it adopts a complex higher-order RNA structure that facilitates translation by binding simultaneously to both eukaryotic initiation factor (eIF) 4F and the 5′ UTR of the viral genome. The specificity of 3′CITE binding to eIF4F is mediated, at least in part, through a direct interaction with its eIF4E subunit, whereas its association with the viral 5′ UTR relies on complementary RNA–RNA base-pairing. We show for the first time that this tripartite 5′ UTR/3′CITE/eIF4F complex forms in vitro in a translationally relevant environment and is required for recruitment of ribosomes to the 5′ end of the viral RNA genome by a mechanism that shares some fundamental features with cap-dependent translation. Notably, our results demonstrate that the 3′CITE facilitates the initiation step of translation and validate a molecular model that has been proposed to explain how several different classes of 3′CITE function. Moreover, the virus–host interplay defined in this study provides insights into natural host resistance mechanisms that have been linked to 3′CITE activity. 相似文献
902.
Airich LG Tsyrenzhapova IS Vorontsova OV Feofanov AV Doroshenko VG Mashko SV 《Journal of molecular microbiology and biotechnology》2010,19(4):189-197
YddG is an inner membrane protein (IMP) that exports aromatic amino acids in Escherichia coli. Topology models of YddG produced by sequence-based analysis in silico have predicted the presence of 9 or 10 potential transmembrane segments. To experimentally analyze the membrane topology of YddG, we used randomly created fusions to β-lactamase (BlaM) as a reporter. The selection of such fusions under 50 μg/ml of ampicillin had to fit with the periplasmic location of the BlaM domain. Five periplasmic loops of YddG predicted by the 10-transmembrane (TM) helices model were identified via the characterization of 12 unique in-frame fusions distributed along the yddG coding region. To confirm the 10-TM helices model further, cytoplasmic regions of YddG were identified with the help of ZsGreen fluorescent protein as a reporter. The presence of four cytoplasmic regions and the cytoplasmic localization of the C-terminus were revealed. Therefore, a 10-TM helices topology with cytoplasmic locations of the N- and C-termini is supported. The present data confirm the 'positive-inside rule' for IMPs and the early results of other workers regarding the cytoplasmic location of the C-terminus of YddG. The pole-specific localization of YddG-ZsGreen in E. coli cells was detected by fluorescence microscopy. 相似文献
903.
Background
Both somatic copy number alterations (CNAs) and germline copy number variants (CNVs) that are prevalent in healthy individuals can appear as recurrent changes in comparative genomic hybridization (CGH) analyses of tumors. In order to identify important cancer genes CNAs and CNVs must be distinguished. Although the Database of Genomic Variants (DGV) contains a list of all known CNVs, there is no standard methodology to use the database effectively. 相似文献904.
Jacques Le Derout Irina V Boni Philippe Régnier Eliane Hajnsdorf 《BMC molecular biology》2010,11(1):17
Background
The bacterial Lsm protein, Hfq, is an RNA chaperone involved in many reactions related to RNA metabolism, such as replication and stability, control of small RNA activity and polyadenylation. Despite this wide spectrum of known functions, the global role of Hfq is almost certainly undervalued; its capacity to bind DNA and to interact with many other proteins are only now beginning to be taken into account. 相似文献905.
Irina Y Lebedeva Vladimir A Lebedev Roland Grossmann Nahid Parvizi 《Reproductive biology and endocrinology : RB&E》2010,8(1):15
Background
The ovaries are the primary targets of senescence effects in mammalian and avian species. In the present study, relationships between reproductive aging, sex steroids and the growth pattern of the pre-ovulatory follicle wall were investigated using young hens with long clutch (YLC), old hens with long clutch (OLC), old hens with short clutch (OSC), and old hens with interrupted long clutch (OILC). 相似文献906.
907.
908.
Yan Z. Voloshin Irina G. Makarenko Semen V. Svidlov Ekaterina G. Lebed Mikhail E. Gurskii 《Inorganica chimica acta》2010,363(2):395-403
The direct template condensation of diacetylmonooxime hydrazone with the 1,4-pentadienylboronates as Lewis acids on an iron(II) ion matrix led to the 1,4-pentadienylboron-capped semiclathrochelate iron(II) oximehydrazonates. The H+-ion-catalyzed macrocyclization of these precursors with an excess of triethyl orthoformate resulted in macrobicyclic complexes with a single apical 1,4-pentadienyl substituent. The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, 1H, 11B{1H} and 13C{1H} NMR, 57Fe Mössbauer spectroscopies, and X-ray crystallography. The X-ray diffraction and NMR data for complexes obtained showed the syn,syn,syn-orientation of all ethoxy substituents in 1,3,5-triazacyclohexane capping fragment in relation to a clathrochelate framework. 相似文献
909.
Pilar Santolaria Fernando López-Gatius Irina García-Ispierto Gregori Bech-Sàbat Eduardo Angulo Teresa Carretero Jóse Antonio Sánchez-Nadal Jesus Yániz 《International journal of biometeorology》2010,54(1):93-98
The aim of this study was to determine possible relationships between farm climate conditions, recorded from day 0 to day
40 post-artificial insemination (AI), and late embryo/early fetal loss in high producing dairy cows. Pregnancy was diagnosed
by rectal ultrasonography between 28 and 34 days post-AI. Fetal loss was registered when a further 80- to 86-day diagnosis
proved negative. Climate variables such as air temperature and relative humidity (RH) were monitored in the cubicles area
for each 30-min period. Temperature-humidity indices (THI); cumulative stressful values and episodes of acute change (defined
as the mean daily value 1.2 times higher or lower than the mean daily values of the 10 previous days) of the climate variables
were calculated. The data were derived from 759 cows in one herd. A total of 692 pregnancies (91.2%) carried singletons and
67 (8.8%) carried twins. No triplets were recorded. Pregnancy loss was recorded in 6.7% (51/759) of pregnancies: 5.6% (39/692)
in single and 17.9% (12/67) in twin pregnancies. Using logistic regression procedures, a one-unit increase in the daily cumulative
number of hours for the THI values higher than 85 during days 11–20 of gestation caused a 1.57-fold increase in the pregnancy
loss, whereas the likelihood of fetal loss increased by a factor of 1.16 for each additional episode of acute variation for
the maximum THI values during gestation days 0–40. THI values higher than 85 and episodes of acute variation for the maximum
THI values were only recorded during the warm and cool periods, respectively. The presence of twins led to a 3.98-fold increase
in pregnancy loss. In conclusion, our findings show that cumulative stressful and episodes of acute variation of climatic
conditions can compromise the success of gestation during both the cool and warm periods of the year. Twin pregnancy was confirmed
as a main factor associated with pregnancy loss. 相似文献
910.
Boris R. Krasnov David Mouillot Irina S. Khokhlova Natalia P. Korallo-Vinarskaya 《International journal for parasitology》2010,40(7):807-817
Different host species harbour parasite faunas that are anywhere from very similar to very different in species composition. A priori, the similarity in the parasite faunas of any two host species should decrease with increases in either the phylogenetic distance, the distinctness of the environments occupied or the geographical distance between these hosts. We tested these predictions using extensive data on the faunas of fleas (Insecta: Siphonaptera) and gamasid mites (Acari: Parasitiformes) parasitic on rodents across the Palaearctic. For each pair of host species, we computed the similarity in parasite faunas based on both species composition as well as the phylogenetic and/or taxonomic distinctness of parasite species. Phylogenetic distances between hosts were based on patristic distances through a rodent phylogeny, geographic distances were computed from geographic range data, and environmental dissimilarity was measured from the average climatic and vegetation scores of each host range. Using multiple regressions on distance matrices to assess the separate explanatory power of each of the three dependent variables, environmental dissimilarity between the ranges of host species emerged as the best predictor of dissimilarity between parasite faunas, especially for fleas; in the case of mites, phylogenetic distance between host species was also important. A closer look at the data indicates that the flea and mite faunas of two hosts inhabiting different environments are always different, whilst hosts living in similar environments can have either very similar or dissimilar parasite faunas. Additional tests showed that dissimilarity in flea or mite faunas between host geographic ranges was best explained by dissimilarity in vegetation, followed by dissimilarity in climatic conditions. Thus, external environmental factors may play greater roles than commonly thought in the evolution of host-parasite associations. 相似文献