全文获取类型
收费全文 | 927篇 |
免费 | 55篇 |
出版年
2022年 | 8篇 |
2021年 | 8篇 |
2019年 | 13篇 |
2018年 | 24篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 40篇 |
2014年 | 35篇 |
2013年 | 41篇 |
2012年 | 69篇 |
2011年 | 58篇 |
2010年 | 40篇 |
2009年 | 40篇 |
2008年 | 35篇 |
2007年 | 49篇 |
2006年 | 44篇 |
2005年 | 37篇 |
2004年 | 40篇 |
2003年 | 47篇 |
2002年 | 33篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 20篇 |
1997年 | 7篇 |
1996年 | 13篇 |
1995年 | 20篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1987年 | 9篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 13篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1969年 | 5篇 |
1937年 | 4篇 |
1936年 | 4篇 |
1933年 | 6篇 |
1932年 | 4篇 |
排序方式: 共有982条查询结果,搜索用时 93 毫秒
931.
As rational adults, we are free to elect what is (or is not) done to our bodies. However, this strong freedom does not extend
to the borders of life. Control over the uses of our biological material is constrained and uncertain at law. Our article
examines the legal condition of embryos and organs: how law conceptualises them and regulates their uses. 相似文献
932.
933.
L. C. Beadle 《Journal of Zoology》1974,173(4):539-548
Synopsis. This article has been composed at the request of the Committee of the Nuffield Unit of Tropical Animal Ecology (NUTAE) at its final meeting in Cambridge in October 1971 and has benefited from the comments of the Committee Members and the two successive directors. It is a short record of the history and aims of the Unit and includes only a superficial review of the research done, though a full list of publications is appended. It refers to the ten years ending in 1971 during which it was basically financed by the Nuffield Foundation and after which it was transferred to the Uganda Institute of Ecology. For an account of the previous development of interest in conservation and research on African wildlife see Worthington, E. B. (1961). The wild resources of East and Central Africa. London. H.M.S.O. 相似文献
934.
935.
936.
Bernadette J. Connors Charles A. Maynard William A. Powell 《Biotechnology letters》2001,23(17):1407-1411
Subtracted and size-selected unsubtracted cDNA libraries were created to examine gene expression in the woody tissues of Castanea dentata. A total of 50 clones were sequenced and comparisons were made to the GenBank database. Expression analysis of 20 selected clones revealed that 13 were expressed predominantly in the stem and leaf tissues, while the other seven were present in all tissues examined. 相似文献
937.
938.
Bernadette Coddeville Erwin Regoeczi Gérard Strecker Yves Plancke Geneviève Spik 《Biochimica et Biophysica Acta (BBA)/General Subjects》2000,1475(3):321-328
Five variants of mouse serum transferrin (mTf, designated mTf-I to mTf-V) with respect to carbohydrate composition have been isolated by DEAE-cellulose chromatography in the following relative percentages: mTf-I: 0.55; mTf-II: 0.79; mTf-III: 71.80; mTf-VI: 21.90 and mTf-V: 4.96. The primary structures of the major glycans from mTf-III and mTf-IV were determined by methylation analysis and 1H-nuclear magnetic resonance (NMR) spectroscopy. All glycans possessed a common trimannosyl-N,N′-diacetylchitobiose core. From the glycovariant mTf-III two isomers of a conventional biantennary N-acetyllactosamine type were isolated, in which two N-glycolylneuraminic acid (Neu5Gc) residues are linked to galactose either by a (α2-6) or (α2-3) linkage. A subpopulation of this glycovariant contains a fucose residue (α1-6)-linked to GlcNAc-1. The structure of the major glycan found in variant mTf-IV contained an additional Neu5Gc and possessed the following new type of linkage: Neu5Gc(α2-3)Gal(β1-3)[Neu5Gc(α2-6)]GlcNAc(β1-2)Man(α1-3). In addition to this glycan, a minor compound contained the same antennae linked to Man(α1-6). In fraction mTf-V, which was found to be very heterogeneous by 1H NMR analysis, carbohydrate composition and methylation analysis suggested the presence of tri′-antennary glycans sialylated by Neu5Gc α-2,6- and α-2,3-linked to the terminal galactose residues. In summary, mTf glycans differed from those of other analyzed mammalian transferrins by the presence of Neu5Gc and by a Neu5Gc(α2-6)GlcNAc linkage in trisialylated biantennary structures, reflecting in mouse liver, a high activity of CMP-Neu5Ac hydroxylase and (α2-6)GlcNAc sialyltransferase. 相似文献
939.
Mollie Sue Oremland Bernadette M. Allen † Phillip J. Clapham ‡ Michael J. Moore § Charley Potter ¶ James G. Mead ¶ 《Marine Mammal Science》2010,26(1):1-16
This study's objective was to investigate mandibular fractures in 50 short-finned pilot whales, Globicephala macrorhynchus, from two mass strandings. Based on current theories that this species is sexually dimorphic and polygynous, hypotheses were: (1) males should suffer more frequent or more substantial mandibular fractures than should females, and (2) fracture occurrence should increase with male reproductive maturity and potential correlates of maturity, such as age and length. Fractures were described and correlated with physical characteristics to infer possible explanations for injuries. Mandibular fractures were surprisingly common in males and females, being found in more than half of the animals examined (27/50, or 54% overall; 17/36 or 47% of females and 10/14 or 71% of males). Length was the only correlate of fracture presence; the proportion of animals showing evidence of fracture increased with length. These results offer some support to initial hypotheses, but there must be another set of consequences that contribute to mandibular fractures in females. A combination of intra- and interspecific interactions and life history characteristics may be responsible for fractures. Further research from a larger sample of this and other cetacean species are suggested to help elucidate both the causes and implications of mandibular fractures. 相似文献
940.