全文获取类型
收费全文 | 8138篇 |
免费 | 616篇 |
国内免费 | 53篇 |
出版年
2021年 | 72篇 |
2020年 | 43篇 |
2019年 | 79篇 |
2018年 | 104篇 |
2017年 | 87篇 |
2016年 | 109篇 |
2015年 | 160篇 |
2014年 | 227篇 |
2013年 | 561篇 |
2012年 | 351篇 |
2011年 | 336篇 |
2010年 | 218篇 |
2009年 | 203篇 |
2008年 | 318篇 |
2007年 | 355篇 |
2006年 | 333篇 |
2005年 | 344篇 |
2004年 | 377篇 |
2003年 | 323篇 |
2002年 | 371篇 |
2001年 | 306篇 |
2000年 | 343篇 |
1999年 | 286篇 |
1998年 | 112篇 |
1997年 | 88篇 |
1996年 | 57篇 |
1995年 | 89篇 |
1994年 | 74篇 |
1993年 | 67篇 |
1992年 | 178篇 |
1991年 | 232篇 |
1990年 | 177篇 |
1989年 | 172篇 |
1988年 | 198篇 |
1987年 | 168篇 |
1986年 | 146篇 |
1985年 | 139篇 |
1984年 | 107篇 |
1983年 | 84篇 |
1982年 | 63篇 |
1981年 | 70篇 |
1980年 | 56篇 |
1979年 | 77篇 |
1978年 | 71篇 |
1977年 | 47篇 |
1976年 | 42篇 |
1975年 | 44篇 |
1974年 | 41篇 |
1973年 | 45篇 |
1972年 | 38篇 |
排序方式: 共有8807条查询结果,搜索用时 281 毫秒
1.
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
2.
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
3.
4.
Miguel Angel Pujana Monica Gratacós Jordi Corral Isabel Banchs Aurora Sánchez David Genís Carlos Cervera Víctor Volpini X. Estivill 《Human genetics》1997,101(1):18-21
Genetic anticipation – increasing severity and a decrease in the age of onset with successive generations of a pedigree –
is clearly present in autosomal dominant cerebellar ataxia (ADCA). Anticipation is correlated with expansion of the CAG/CTG
repeat sequence to sizes above those in the normal range through the generations of a pedigree. Genetic heterogeneity has
been demonstrated for ADCA, with four cloned genes (SCA1, SCA2, SCA3/MJD, and SCA6) and three mapped loci (SCA4, SCA5 and
SCA7). Another related dominant ataxia, dentatorubral-pallidoluysian atrophy (DRPLA), presents anticipation with CAG/CTG repeat
expansions. We had previously analysed ADCA patients who had not shown repeat expansions in cloned genes for CAG/CTG repeat
expansions by the repeat expansion detection method (RED) and had detected expansions of between 48 and 88 units in 17 unrelated
familial cases. We present here an analysis of 13 genes and expressed sequence tags (ESTs) containing 10 or more CAG/ CTG
repeat sequences selected from public databases in the 17 unrelated ADCA patients. Of the 13 selected genes and ESTs, 9 were
found to be polymorphic with heterozygosities ranging between 0.09 and 0.80 and 2 to 17 alleles. In ADCA patients none of
the loci showed expansions above the normal range of the CAG/CTG repeat sequences, excluding them as the mutation causing
ADCA.
Received: 28 May 1997 / Accepted: 30 June 1997 相似文献
5.
N. Yamada W. Murata Y. Yamaguchi K.-I. Fujita A. Ogita T. Tanaka 《Letters in applied microbiology》2021,72(4):390-398
Amphotericin B (AmB), a typical polyene macrolide antifungal agent, is widely used to treat systemic mycoses. In the present study, we show that the fungicidal activity of AmB was enhanced by benzyl isothiocyanate (BITC), a cruciferous plant-derived compound, in the budding yeast, Saccharomyces cerevisiae. In addition to forming a molecular complex with ergosterol present in fungal cell membranes to form K+-permeable ion channels, AmB has been recognized to mediate vacuolar membrane disruption resulting in lethal effects. BITC showed no effect on AmB-induced plasma membrane permeability; however, it amplified AmB-induced vacuolar membrane disruption in S. cerevisiae. Furthermore, the BITC-enhanced fungicidal effects of AmB significantly decreased cell viability due to the disruption of vacuoles in the pathogenic fungus Candida albicans. The application of the combinatorial antifungal effect of AmB and BITC may aid in dose reduction of AmB in clinical antifungal therapy and consequently decrease side effects in patients. These results also have significant implications for the development of vacuole-targeting chemotherapy against fungal infections. 相似文献
6.
7.
The specificity for 11-deoxycortisol (11-DOC) of a monoclonal antibody (mAb), designated SCET, was changed to specificity for cortisol (CS) by site-specific mutagenesis followed by random mutagenesis. The Fab form of SCET was expressed on the surface of a phage. During the first step, mutations were introduced at 14 amino acid positions in three complementarity-determining regions (CDRs) of the VH domain that seemed likely to form the steroid-binding pocket. A clone, DcC16, was isolated from the resultant library with multiple mutations and this clone was shown to have CS-binding activity but also to retain high 11-DOC-binding activity. During the second step, mutations were introduced randomly into the entire VH-coding region of the DcC16 clone by an error-prone polymerase chain reaction, and CS-specific mutant antibodies were selected in the presence of 11-DOC as a competitor. Three representative clones were analyzed with the BIAcore instrument, and each revealed a large increase in the binding constant for CS and a decrease in that for 11-DOC. Structural models, constructed by computer simulation, indicated the probable molecular basis for these changes in specificity. 相似文献
8.
A congenital diverticulum of the ileum (Meckel's diverticulum), approximately 10 mm long, was detected in a rat and examined histologically. The histological findings were basically the same as in the ileum. Although Meckel's diverticulum is uncommon in the rat, the present report demonstrated the possibility of discovering new cases. 相似文献
9.
10.