首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   534篇
  免费   85篇
  619篇
  2021年   5篇
  2018年   9篇
  2016年   6篇
  2015年   17篇
  2014年   14篇
  2013年   13篇
  2012年   25篇
  2011年   20篇
  2010年   15篇
  2009年   16篇
  2008年   15篇
  2007年   23篇
  2006年   19篇
  2005年   18篇
  2004年   16篇
  2003年   19篇
  2002年   17篇
  2001年   13篇
  2000年   10篇
  1999年   13篇
  1998年   11篇
  1997年   4篇
  1996年   9篇
  1995年   8篇
  1994年   7篇
  1992年   18篇
  1991年   11篇
  1990年   8篇
  1989年   14篇
  1988年   13篇
  1987年   13篇
  1986年   10篇
  1985年   14篇
  1984年   11篇
  1983年   8篇
  1982年   11篇
  1981年   9篇
  1978年   12篇
  1977年   4篇
  1976年   4篇
  1975年   6篇
  1974年   7篇
  1973年   4篇
  1972年   5篇
  1971年   12篇
  1970年   4篇
  1969年   10篇
  1967年   5篇
  1964年   11篇
  1955年   4篇
排序方式: 共有619条查询结果,搜索用时 15 毫秒
61.
Type 2 diabetes is a serious, genetically influenced disease for which no fully effective treatments are available. Identification of biochemical or regulatory pathways involved in the disease syndrome could lead to innovative therapeutic interventions. One way to identify such pathways is the genetic analysis of families with multiple affected members where disease predisposing genes are likely to be segregating. We undertook a genomewide screen (389-395 microsatellite markers) in samples of 835 white, 591 Mexican American, 229 black, and 128 Japanese American individuals collected as part of the American Diabetes Association's GENNID study. Multipoint nonparametric linkage analyses were performed with diabetes, and diabetes or impaired glucose homeostasis (IH). Linkage to diabetes or IH was detected near markers D5S1404 (map position 77 cM, LOD = 2.80), D12S853 (map position 82 cM, LOD = 2.81) and GATA172D05 (X-chromosome map position 130 cM, LOD = 2.99) in whites, near marker D3S2432 (map position 51 cM, LOD = 3.91) in Mexican Americans, and near marker D10S1412 (map position 14 cM, LOD = 2.39) in African Americans mainly collected in phase 1 of the study. Further analyses showed evidence for interactions between the chromosome 5 locus and region on chromosome 12 containing the MODY 3 gene (map position 132 cM) and between the X-chromosome locus and region near D12S853 (map position 82 cM) in whites. Although these results were not replicated in samples collected in phase 2 of the GENNID study, the region on chromosome 12 was replicated in samples from whites described by Bektas et al. (1999).  相似文献   
62.
Stachybotrys occurring in mouldy indoor environments is associated with the so called “sick building syndrome” in humans or cases of idiopathic pulmonary hemorrhages. Samples of mouldy materials from indoor environments (n=15) were analysed for the occurrence of this fungus and its secondary metabolites by a sensitive LC-MS/MS method. In four samples,Stachybotrys and macrocyclic trichothecenes have been detected. Maximum values for Satratoxin G and H in wallpaper were determined with 9.7 μg/cm2 and 12.0 μg/cm2, respectively.  相似文献   
63.
Sibley and Ahlquist compared the single-copy nuclear DNA sequences of the hominoid primates using DNA-DNA hybridization. From this data set they estimated a phylogeny that clusters man and chimpanzees using a distance Wagner procedure. However, no assessment of statistical confidence in this estimated phylogeny was made, despite the fact that their data set contains internal inconsistencies concerning the correct branching order. This paper presents a modification of Pielou's Q- statistic that allows one to make nonparametric tests of phylogenetic relationship from distance data. The results of this analysis indicate that the estimated phylogeny of Sibley and Ahlquist is without statistical significance owing to the internal inconsistencies of the data set. A survey and additional analyses of other types of molecular data indicate that the phylogeny that clusters chimpanzees and gorillas and has the human lineage splitting off earlier is statistically consistent with all the molecular data (including the DNA-DNA hybridization data), whereas the phylogeny estimated by Sibley and Ahlquist can be rejected at the 5% level using the data on restriction- endonuclease sites in the mitochondrial genome.   相似文献   
64.
Y. YOM-TOV  R. WILSON  AMOS AR 《Ibis》1986,128(1):1-8
The water budget of incubating Jackass Penguin eggs was studied on Marcus Island, South Africa, and complementary measurements were made in the laboratory. The mean ambient temperature was 16-5 "C and the mean humidity was 12-4 Torr (89% relative humidity). The temperature of incubated live and water-filled eggs ranged between 14oCand 37 oC. The mean calculated egg temperature was 34-9' C. The mean brood patch temperature was 37-1 oC, slightly lower than the cloacal temperature (37.8 oC). The mean brood patch area was about 38 cm2. The rate of water loss was 411 mg day-1. The total diffusive water loss during 37 days of incubation was, as predicted, 15-2% of the initial 100-3 g egg mass. The total pore number was 6245 per egg and the shell thickness was 577 fira. It is suggested that the eggshell parameters, incubation length and nesting behaviour are compensated in such a way that an egg-to-nest water vapour pressure difference lower than commonly found is sufficient to bring about the normal total water loss.  相似文献   
65.
66.
We report on genome sequencing of Oligotropha carboxidovorans strain OM4 and resequencing of strain OM5. The genomes of both are composed of one chromosome and two plasmids. The presence of two plasmids in the OM5 genome is inconsistent with the previously published sequence, for which only one plasmid was described (D. Paul, S. Bridges, S. Burgess, Y. Dandass, and M. Lawrence, BMC Genomics 11:511, 2010).  相似文献   
67.
Cell-penetrating peptides (CPPs) may have impli-cations in biomedical sciences by improving the delivery of a wide variety of drugs through the membrane barrier. CPPs are generally taken up by endocytotic pathways, and vesicular encapsulation is a limiting factor in the area of intracellular targeting. A novel, cationic cysteine-rich CPP, CyLoP-1, has been developed exhibiting distinguished diffused cytosolic distribution along with endosomal uptake at low micromolar concentrations. Comparative uptake analysis with known CPPs showed CyLoP-1 as a promising delivery vector to access the cytosol in a variety of cell types. In addition to the positively charged residues, the presence of cysteines and tryptophans proved to be essential to maintain its functionality. Also, the oxidation status of the cysteines played an important role for the uptake efficiency of CyLoP-1, with the disulfide-containing form being more effective. The distinct feature of CyLoP-1 to enter the cytosol was further explored by the covalent attachment of cargoes of different nature and sizes. In particular, induction of caspase-3 activity (indicating apoptosis) by a CyLoP-1-SmacN7 conjugate proved successful delivery of the pro-apoptotic cargo to its site of action in the cytosol. Efficient intracellular delivery into the entire cytosol already at low micromolar concentrations makes CyLoP-1 a promising candidate for cytosolic delivery of cargoes of small sizes. Thus, this peptide might prove to be useful for efficient transmembrane delivery of agents directed to cytosolic targets.  相似文献   
68.

Background  

Existing cut-offs for fasting plasma glucose (FPG) and post-load glucose (2hPG) criteria are not equivalent in the diagnosis of diabetes and glucose intolerance. Adjusting cut-offs of single measurements have not helped so we undertook this project to see if they could be complementary.  相似文献   
69.
70.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号