全文获取类型
收费全文 | 83篇 |
免费 | 0篇 |
专业分类
现状及发展 | 29篇 |
研究方法 | 11篇 |
综合类 | 43篇 |
出版年
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 4篇 |
2009年 | 1篇 |
2008年 | 4篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1989年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1956年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有83条查询结果,搜索用时 281 毫秒
41.
42.
T M Schuster 《Nature》1966,209(5020):302-303
43.
P Cuisinier-Gleizes A George M Thomasset H Mathieu 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1975,280(18):2145-2148
Chronic metabolic acidosis entails hyperparathyroidism and osteopathy. In order to elucidate the role of the thyroparathyroids in this bone lesion production the effects of acidic diet for 7 weeks were studied in parathyroidectomized (PTX), thyroparathyroidectomized (TPTX) and shamoperated (Sh-O) growing rats. In all animals urinary excretion of calcium, phosphate, ammonium and titrable acidity was similarly increased. The rise in hydroxyproline excretion and urinary 85-sr (that was injected previous to acidic feeding) was more marked in PTX and TPTX rats. Moreover, in these animals the serum calcium level was increased, the blood pH was decreased. According to these data, an acidic diet intake that is not sufficient to elicit a fall in blood pH of normal young rats can induce severe acidosis in chronically parathyroidectomized or thyroparathyroidectomized animals; moreover the bone resorption appears more marked. It is concluded that parathyroids are involved in the extra-cellular fluid defense mechanism against acidosis by a no bone resorptive mechanism. We hypothesize that the parathyroids permit the necessary and adequate supply of bicarbonates by the bone to maintain blood pH homeostasis. 相似文献
44.
Summary Culturing amphibian embryonic cells on different supports suggests the important role played by the contact between support and cellular membrane in spreading and morphological differentiation of these cells. They spread on glass but do not spread when glass is covered by acrylamide gels (3%, 7% and 9%), by acrylamide-carboxymethylcellulose, or acrylamide-hydroxyethylcellulose gels, or by agarose gel (1,5%). Nevertheless, cells spread and differentiate on mixed acrylamide (7% or 9%) agarose (0.80%) gels. 相似文献
45.
Forest F Grenyer R Rouget M Davies TJ Cowling RM Faith DP Balmford A Manning JC Procheş S van der Bank M Reeves G Hedderson TA Savolainen V 《Nature》2007,445(7129):757-760
One of the biggest challenges for conservation biology is to provide conservation planners with ways to prioritize effort. Much attention has been focused on biodiversity hotspots. However, the conservation of evolutionary process is now also acknowledged as a priority in the face of global change. Phylogenetic diversity (PD) is a biodiversity index that measures the length of evolutionary pathways that connect a given set of taxa. PD therefore identifies sets of taxa that maximize the accumulation of 'feature diversity'. Recent studies, however, concluded that taxon richness is a good surrogate for PD. Here we show taxon richness to be decoupled from PD, using a biome-wide phylogenetic analysis of the flora of an undisputed biodiversity hotspot--the Cape of South Africa. We demonstrate that this decoupling has real-world importance for conservation planning. Finally, using a database of medicinal and economic plant use, we demonstrate that PD protection is the best strategy for preserving feature diversity in the Cape. We should be able to use PD to identify those key regions that maximize future options, both for the continuing evolution of life on Earth and for the benefit of society. 相似文献
46.
Stoepker C Hain K Schuster B Hilhorst-Hofstee Y Rooimans MA Steltenpool J Oostra AB Eirich K Korthof ET Nieuwint AW Jaspers NG Bettecken T Joenje H Schindler D Rouse J de Winter JP 《Nature genetics》2011,43(2):138-141
DNA interstrand crosslink repair requires several classes of proteins, including structure-specific endonucleases and Fanconi anemia proteins. SLX4, which coordinates three separate endonucleases, was recently recognized as an important regulator of DNA repair. Here we report the first human individuals found to have biallelic mutations in SLX4. These individuals, who were previously diagnosed as having Fanconi anemia, add SLX4 as an essential component to the FA-BRCA genome maintenance pathway. 相似文献
47.
A single particle confined in an asymmetric potential demonstrates an anticipated ratchet effect by drifting along the 'easy' ratchet direction when subjected to non-equilibrium fluctuations. This well-known effect can, however, be dramatically changed if the potential captures several interacting particles. Here we demonstrate that the inter-particle interactions in a chain of repelling particles captured by a ratchet potential can, in a controllable way, lead to multiple drift reversals, with the drift sign alternating from positive to negative as the number of particles per ratchet period changes from odd to even. To demonstrate experimentally the validity of this very general prediction, we performed transport measurements on a.c.-driven vortices trapped in a superconductor by an array of nanometre-scale asymmetric traps. We found that the direction of the vortex drift does undergo multiple reversals as the vortex density is increased, in excellent agreement with the model predictions. This drastic change in the drift behaviour between single- and multi-particle systems can shed some light on the different behaviour of ratchets and biomembranes in two drift regimes: diluted (single particles) and concentrated (interacting particles). 相似文献
48.
The contribution of bone to whole-organism physiology 总被引:1,自引:0,他引:1
The mouse genetic revolution has shown repeatedly that most organs have more functions than expected. This has led to the realization that, in addition to a molecular and cellular approach, there is a need for a whole-organism study of physiology. The skeleton is an example of how a whole-organism approach to physiology can broaden the functions of a given organ, reveal connections of this organ with others such as the brain, pancreas and gut, and shed new light on the pathogenesis of degenerative diseases affecting multiple organs. 相似文献
49.
A D'Hont F Denoeud JM Aury FC Baurens F Carreel O Garsmeur B Noel S Bocs G Droc M Rouard C Da Silva K Jabbari C Cardi J Poulain M Souquet K Labadie C Jourda J Lengellé M Rodier-Goud A Alberti M Bernard M Correa S Ayyampalayam MR Mckain J Leebens-Mack D Burgess M Freeling D Mbéguié-A-Mbéguié M Chabannes T Wicker O Panaud J Barbosa E Hribova P Heslop-Harrison R Habas R Rivallan P Francois C Poiron A Kilian D Burthia C Jenny F Bakry S Brown V Guignon G Kema M Dita C Waalwijk S Joseph A Dievart 《Nature》2012,488(7410):213-217
Bananas (Musa spp.), including dessert and cooking types, are giant perennial monocotyledonous herbs of the order Zingiberales, a sister group to the well-studied Poales, which include cereals. Bananas are vital for food security in many tropical and subtropical countries and the most popular fruit in industrialized countries. The Musa domestication process started some 7,000 years ago in Southeast Asia. It involved hybridizations between diverse species and subspecies, fostered by human migrations, and selection of diploid and triploid seedless, parthenocarpic hybrids thereafter widely dispersed by vegetative propagation. Half of the current production relies on somaclones derived from a single triploid genotype (Cavendish). Pests and diseases have gradually become adapted, representing an imminent danger for global banana production. Here we describe the draft sequence of the 523-megabase genome of a Musa acuminata doubled-haploid genotype, providing a crucial stepping-stone for genetic improvement of banana. We detected three rounds of whole-genome duplications in the Musa lineage, independently of those previously described in the Poales lineage and the one we detected in the Arecales lineage. This first monocotyledon high-continuity whole-genome sequence reported outside Poales represents an essential bridge for comparative genome analysis in plants. As such, it clarifies commelinid-monocotyledon phylogenetic relationships, reveals Poaceae-specific features and has led to the discovery of conserved non-coding sequences predating monocotyledon-eudicotyledon divergence. 相似文献