全文获取类型
收费全文 | 238篇 |
免费 | 2篇 |
专业分类
系统科学 | 2篇 |
丛书文集 | 1篇 |
教育与普及 | 1篇 |
理论与方法论 | 10篇 |
现状及发展 | 91篇 |
研究方法 | 28篇 |
综合类 | 103篇 |
自然研究 | 4篇 |
出版年
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 4篇 |
2012年 | 14篇 |
2011年 | 17篇 |
2010年 | 5篇 |
2009年 | 1篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 17篇 |
2005年 | 20篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 17篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1977年 | 7篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1971年 | 5篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1968年 | 6篇 |
1967年 | 2篇 |
1966年 | 3篇 |
1965年 | 3篇 |
1954年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有240条查询结果,搜索用时 15 毫秒
211.
212.
213.
G. L. Sottocasa N. Stagni B. de Bernard 《Cellular and molecular life sciences : CMLS》1971,27(10):1247-1248
Zusammenfassung Es wird eine raschere und empfindlichere Methode zur Bestimmung der Aktivität von Dioldehydrase beschrieben. 相似文献
214.
215.
216.
D. Bernard J. -C. Maurizis C. Nicolas J. Michelot G. Bétail G. Meyniel 《Cellular and molecular life sciences : CMLS》1985,41(3):385-387
Summary Antibodies reacting with 3,5,3,5 tetraiodo-l-tyrosyl-l-tyrosine (I2Tyr-I2Tyr) were elicited in rabbits by immunization with an oxidized yeast conjugate coupled with I2Tyr-I2Tyr. Ion-exchange chromatography was used to purify immunoglobulins, in order to improve the specificity in measurement of I2Tyr-I2Tyr level in patient serum. IgG binding capacity versus I2Tyr-I2Tyr was considerably increased after immunoglobulin purification.Acknowledgments. The authors with to thank Mrs M. Ollier for her valuable technical assistance. 相似文献
217.
Jaeger JJ Beard KC Chaimanee Y Salem M Benammi M Hlal O Coster P Bilal AA Duringer P Schuster M Valentin X Marandat B Marivaux L Métais E Hammuda O Brunet M 《Nature》2010,467(7319):1095-1098
Reconstructing the early evolutionary history of anthropoid primates is hindered by a lack of consensus on both the timing and biogeography of anthropoid origins. Some prefer an ancient (Cretaceous) origin for anthropoids in Africa or some other Gondwanan landmass, whereas others advocate a more recent (early Cenozoic) origin for anthropoids in Asia, with subsequent dispersal of one or more early anthropoid taxa to Africa. The oldest undoubted African anthropoid primates described so far are three species of the parapithecid Biretia from the late middle Eocene Bir El Ater locality of Algeria and the late Eocene BQ-2 site in the Fayum region of northern Egypt. Here we report the discovery of the oldest known diverse assemblage of African anthropoids from the late middle Eocene Dur At-Talah escarpment in central Libya. The primate assemblage from Dur At-Talah includes diminutive species pertaining to three higher-level anthropoid clades (Afrotarsiidae, Parapithecidae and Oligopithecidae) as well as a small species of the early strepsirhine primate Karanisia. The high taxonomic diversity of anthropoids at Dur At-Talah indicates either a much longer interval of anthropoid evolution in Africa than is currently documented in the fossil record or the nearly synchronous colonization of Africa by multiple anthropoid clades at some time during the middle Eocene epoch. 相似文献
218.
Mutations in MRAP, encoding a new interacting partner of the ACTH receptor, cause familial glucocorticoid deficiency type 2 总被引:10,自引:0,他引:10
Metherell LA Chapple JP Cooray S David A Becker C Rüschendorf F Naville D Begeot M Khoo B Nürnberg P Huebner A Cheetham ME Clark AJ 《Nature genetics》2005,37(2):166-170
Familial glucocorticoid deficiency (FGD), or hereditary unresponsiveness to adrenocorticotropin (ACTH; OMIM 202200), is an autosomal recessive disorder resulting from resistance to the action of ACTH on the adrenal cortex, which stimulates glucocorticoid production. Affected individuals are deficient in cortisol and, if untreated, are likely to succumb to hypoglycemia or overwhelming infection in infancy or childhood. Mutations of the ACTH receptor (melanocortin 2 receptor, MC2R) account for approximately 25% of cases of FGD. FGD without mutations of MC2R is called FGD type 2. Using SNP array genotyping, we mapped a locus involved in FGD type 2 to chromosome 21q22.1. We identified mutations in a gene encoding a 19-kDa single-transmembrane domain protein, now known as melanocortin 2 receptor accessory protein (MRAP). We show that MRAP interacts with MC2R and may have a role in the trafficking of MC2R from the endoplasmic reticulum to the cell surface. 相似文献
219.
Parallel evolution of similar traits in independent populations that inhabit ecologically similar environments strongly implicates natural selection as the cause of evolution. Parallel speciation is a special form of parallel evolution where traits that determine reproductive isolation evolve repeatedly, in closely related populations, as by-products of adaptation to ecological conditions. The outcome of such parallel evolution is that ecologically divergent pairs of populations exhibit greater levels of reproductive isolation than ecologically similar pairs of populations of a similar or younger age. The parallel evolution of reproductive isolation provides strong evidence for natural selection in the process of speciation, but only one conclusive example from nature is known. Populations of the walking-stick insect Timema cristinae that use different host-plant species have diverged in body size and shape, host preference, behaviour and the relative frequency of two highly cryptic colour-pattern morphs. Here we report that divergent selection for host adaptation, and not genetic drift, has promoted the parallel evolution of sexual isolation in this species. Our findings represent a clear demonstration that host-plant adaptation can play a crucial and repeatable role in the early stages of speciation. 相似文献
220.
Zusammenfassung Funktionsdynamik von Gehirn-Norepinephrin (NE) in kastrierten und scheinkastrierten männlichen, geschlechtsreifen (C57Br/6J)-Mäusen wurde nach 13 Monaten Isolierung untersucht. Kastrierung bewirkt starken Abfall des ursprünglichen Niveaus und der Stoffwechselgeschwinddigkeit von NE.
Supported in part by a USPHS Predoctoral Fellowship toB. K. Bernard and NIMH Grant No. MH 15352 toR. M. Paolino. 相似文献
Supported in part by a USPHS Predoctoral Fellowship toB. K. Bernard and NIMH Grant No. MH 15352 toR. M. Paolino. 相似文献