全文获取类型
收费全文 | 9870篇 |
免费 | 691篇 |
国内免费 | 1篇 |
出版年
2021年 | 66篇 |
2020年 | 49篇 |
2019年 | 90篇 |
2018年 | 113篇 |
2017年 | 99篇 |
2016年 | 144篇 |
2015年 | 219篇 |
2014年 | 310篇 |
2013年 | 649篇 |
2012年 | 457篇 |
2011年 | 458篇 |
2010年 | 305篇 |
2009年 | 303篇 |
2008年 | 485篇 |
2007年 | 508篇 |
2006年 | 484篇 |
2005年 | 491篇 |
2004年 | 509篇 |
2003年 | 411篇 |
2002年 | 481篇 |
2001年 | 298篇 |
2000年 | 341篇 |
1999年 | 293篇 |
1998年 | 117篇 |
1997年 | 90篇 |
1996年 | 74篇 |
1995年 | 92篇 |
1994年 | 83篇 |
1993年 | 82篇 |
1992年 | 189篇 |
1991年 | 233篇 |
1990年 | 180篇 |
1989年 | 170篇 |
1988年 | 196篇 |
1987年 | 167篇 |
1986年 | 147篇 |
1985年 | 142篇 |
1984年 | 119篇 |
1983年 | 97篇 |
1982年 | 68篇 |
1981年 | 73篇 |
1980年 | 58篇 |
1979年 | 80篇 |
1978年 | 72篇 |
1977年 | 50篇 |
1976年 | 42篇 |
1975年 | 44篇 |
1974年 | 42篇 |
1973年 | 46篇 |
1972年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
Z. Kato Seiji Fukuda Shunji Tomatsu Hugo Vega Teruo Yasunaga Atsushi Yamagishi Naoto Yamada A. Valencia Luis Alejandro Barrera Kazuko Sukegawa Tadao Orii Naomi Kondo 《Human genetics》1997,101(1):97-101
Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive lysosomal storage disorder caused by a genetic defect in N-acetylgalactosamine-6-sulfate
sulfatase (GALNS). In previous studies, we have found two common mutations in Caucasians and Japanese, respectively. To characterize
the mutational spectrum in various ethnic groups, mutations in the GALNS gene in Colombian MPS IVA patients were investigated,
and genetic backgrounds were extensively analyzed to identify racial origin, based on mitochondrial DNA (mtDNA) lineages.
Three novel missense mutations never identified previously in other populations and found in 16 out of 19 Colombian MPS IVA
unrelated alleles account for 84.2% of the alleles in this study. The G301C and S162F mutations account for 68.4% and 10.5%
of mutations, respectively, whereas the remaining F69V is limited to a single allele. The skewed prevalence of G301C in only
Colombian patients and haplotype analysis by restriction fragment length polymorphisms in the GALNS gene suggest that G301C
originated from a common ancestor. Investigation of the genetic background by means of mtDNA lineages indicate that all our
patients are probably of native American descent.
Received: 2 January 1997 / Accepted: 10 June 1997 相似文献
3.
Molecular and Biochemical Characterization of Three Anthocyanin Synthetic Enzymes from Gentiana triflora 总被引:5,自引:0,他引:5
Tanaka Yoshikazu; Yonekura Keiko; Fukuchi-Mizutani Masako; Fukui Yuko; Fujiwara Hiroyuki; Ashikari Toshihiko; Kusumi Takaaki 《Plant & cell physiology》1996,37(5):711-716
Full length cDNA clones of flavonoid 3',5'-hydroxylase, dihydroflavonol4-reductase and flavonoid 3-glucosyltransferase were clonedfrom petals of Gentiana triflora. Their sequences were homologousto counterparts from other plants. Flavonoid 3',5'-hydroxylaseand flavonoid 3-glucosyltransferase were enzymatically characterizedby expressing cDNAs in heterologous expression systems. (Received May 21, 1996; Accepted June 4, 1996) 相似文献
4.
M. Hakoda Naoyuki Kamatani Sakura Kurumada Yuko Hirai Kimitaka Sakamoto Hisashi Yamanaka Chihiro Terai Sadao Kashiwazaki 《Human genetics》1997,99(2):164-170
Both germline and somatic mutations are known to affect phenotypes of human cells in vivo. In previous studies, we cloned
mutant peripheral blood T cells from germline heterozygous humans for adenine phosphoribosyltransferase (APRT) (EC 2.4.2.7)
deficiency and found that approximately 1.3 × 10–4 peripheral T cells had undergone in vivo somatic mutations. Loss of heterozygosity (LOH) was the major cause of the mutations
at the APRT locus since approximately 80% of the mutant T cell clones exhibited loss of normal alleles. In the present study,
we identified three heterozygous individuals for APRT deficiency (representing two separate families), in whom none of the
somatic mutant cells exhibited LOH at the APRT locus. The germline mutant APRT alleles of these heterozygotes from two unrelated
families had the same gross DNA abnormalities detectable by Southern blotting. None of the germline mutant APRT alleles so
far reported had such gross DNA abnormalities. The data suggest that the germline mutation unique to these heterozygous individuals
is associated with the abrogation of LOH in somatic cells. The absence of LOH at a different locus has already been reported
in vitro in an established cell line but the present study describes the first such event in vivo in human individuals.
Received: 10 May 1996 相似文献
5.
6.
Shunsuke Yaguchi Atsuko Yamazaki Wakana Wada Yasutaka Tsuchiya Toshihiko Sato Hideo Shinagawa Yutaro Yamada Junko Yaguchi 《Development, growth & differentiation》2015,57(3):242-250
Sea urchins are model non‐chordate deuterostomes, and studying the nervous system of their embryos can aid in the understanding of the universal mechanisms of neurogenesis. However, despite the long history of sea urchin embryology research, the molecular mechanisms of their neurogenesis have not been well investigated, in part because neurons appear relatively late during embryogenesis. In this study, we used the species Temnopleurus reevesii as a new sea urchin model and investigated the detail of its development and neurogenesis during early embryogenesis. We found that the embryos of T. reevesii were tolerant of high temperatures and could be cultured successfully at 15–30°C during early embryogenesis. At 30°C, the embryos developed rapidly enough that the neurons appeared at just after 24 h. This is faster than the development of other model urchins, such as Hemicentrotus pulcherrimus or Strongylocentrotus purpuratus. In addition, the body of the embryo was highly transparent, allowing the details of the neural network to be easily captured by ordinary epifluorescent and confocal microscopy without any additional treatments. Because of its rapid development and high transparency during embryogenesis, T. reevesii may be a suitable sea urchin model for studying neurogenesis. Moreover, the males and females are easily distinguishable, and the style of early cleavages is intriguingly unusual, suggesting that this sea urchin might be a good candidate for addressing not only neurology but also cell and developmental biology. 相似文献
7.
Y. Yamada 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1995,91(4):655-658
Conclusions The comparison of different selection indices is justified only if the indices are constrated to achieve the same profit function, even when each index is not optimized with respect to that profit function.When a profit function is known and is non-linear, the desired gains index may be more efficient than the economic index. The optimum desired gains index should be determined by iterative techniques over several generations to compare the genetic progress with the economic index, because gains by the economic index are not linear and the changes observed in the initial generations of selection are not the same rates in future generations, although those changes are linear in the case of the desired gains index. 相似文献
8.
9.
10.
Genotoxicity of ptaquiloside, a bracken carcinogen, in the hepatocyte primary culture/DNA-repair test 总被引:2,自引:0,他引:2
The genotoxicity of ptaquiloside (PT), recently isolated from bracken fern and shown to be carcinogenic, was examined by means of the hepatocyte primary culture/DNA-repair test. PT elicited clear unscheduled DNA synthesis with a dose-response effect. The result indicates that PT is a genotoxic carcinogen. 相似文献