全文获取类型
收费全文 | 11269篇 |
免费 | 1034篇 |
国内免费 | 1篇 |
出版年
2022年 | 98篇 |
2021年 | 202篇 |
2020年 | 116篇 |
2019年 | 152篇 |
2018年 | 197篇 |
2017年 | 156篇 |
2016年 | 274篇 |
2015年 | 511篇 |
2014年 | 545篇 |
2013年 | 619篇 |
2012年 | 863篇 |
2011年 | 778篇 |
2010年 | 521篇 |
2009年 | 472篇 |
2008年 | 701篇 |
2007年 | 659篇 |
2006年 | 604篇 |
2005年 | 612篇 |
2004年 | 598篇 |
2003年 | 579篇 |
2002年 | 512篇 |
2001年 | 116篇 |
2000年 | 100篇 |
1999年 | 112篇 |
1998年 | 174篇 |
1997年 | 121篇 |
1996年 | 123篇 |
1995年 | 116篇 |
1994年 | 95篇 |
1993年 | 76篇 |
1992年 | 89篇 |
1991年 | 73篇 |
1990年 | 74篇 |
1989年 | 61篇 |
1988年 | 75篇 |
1987年 | 53篇 |
1986年 | 63篇 |
1985年 | 72篇 |
1984年 | 81篇 |
1983年 | 61篇 |
1982年 | 61篇 |
1981年 | 74篇 |
1980年 | 59篇 |
1979年 | 59篇 |
1978年 | 54篇 |
1977年 | 48篇 |
1976年 | 41篇 |
1974年 | 41篇 |
1973年 | 43篇 |
1970年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
161.
Comparative chromosome painting between two marsupials: origins of an XX/XY1Y2 sex chromosome system
Roland Toder Rachel J. W. O’Neill Johannes Wienberg Patricia C. M. O’Brien Lucille Voullaire Jennifer A. Marshall-Graves 《Mammalian genome》1997,8(6):418-422
Cross-species chromosome painting was used to investigate genome rearrangements between tammar wallaby Macropus eugenii (2n = 16) and the swamp wallaby Wallabia bicolor (2n = 10♀/11♂), which diverged about 6 million years ago. The swamp wallaby has an XX female:XY1Y2 male sex chromosome system thought to have resulted from a fusion between an autosome and the small original X, not involving
the Y. Thus, the small Y1 should represent the original Y and the large Y2 the original autosome. DNA paints were prepared from flow-sorted and microdissected chromosomes from the tammar wallaby.
Painting swamp wallaby spreads with each tammar chromosome-specific probe gave extremely strong and clear signals in single-,
two-, and three-color FISH. These showed that two tammar wallaby autosomes are represented unchanged in the swamp wallaby,
two are represented by different centric fusions, and one by a tandem fusion to make the very long arms of swamp wallaby Chromosome
(Chr) 1. The large swamp wallaby X comprises the tammar X as its short arm, and a tandemly fused 7 and 2 as the long arm.
The acrocentric swamp wallaby Y2 is a 2/7 fusion, homologous with the long arm of the X. The small swamp wallaby Y1 is confirmed as the original Y by its painting with the tammar Y. However, the presence of sequences shared between the microdissected
tammar Xp and Y on the swamp wallaby Y2 implies that the formation of the compound sex chromosomes involved addition of autosome(s) to both the original X and Y.
We propose that this involved fusion with an ancient pseudoautosomal region followed by fission proximal to this shared region.
Received: 16 October 1996/Accepted: 30 January 1997 相似文献
162.
Xiangning Deng Jennifer Moran Neal G. Copeland Debra J. Gilbert Nancy A. Jenkins Paul Primakoff Patricia A. Martin-DeLeon 《Mammalian genome》1997,8(2):94-97
We have determined the chromosomal localization of the murine gene encoding the 68-kDa sperm adhesion molecule 1, Spam1 or Ph-20. Using two independent approaches, fluorescence in situ hybridization (FISH) and interspecific backcross analysis, we show
that Spam1 maps to proximal mouse Chromosome (Chr) 6. This map position is within the conserved linkage group corresponding to human
Chr 7q, where the human homolog, SPAM 1, has been shown to map previously. Genetic mapping shows the gene to be very closely
linked to Met, one of the most proximal loci on MMU 6. It thus places the gene near the centromere and the junction of the Rb(6.16)24Lub
and Rb(6.15)1Ald translocations. The essential role of the Spam1 sperm antigen in mouse sperm-egg interactions and its gene
location provide strong support for its candidacy as the gene involved in the dysfunction of mouse sperm bearing the Rb(6.16)24Lub
or Rb(6.15)1Ald translocation.
Received: 16 July 1996 / Accepted: 23 September 1996 相似文献
163.
Kyle A. Serikawa Patricia C. Zambryski 《The Plant journal : for cell and molecular biology》1997,11(4):863-869
Domain exchange constructs that traded regions surrounding the homeodomain were constructed for two kn1 -like genes, KNAT1 and KNAT3, and introduced into Arabidopsis thaliana under the control of the 35S CaMV promoter. The kn1-like homeodomain proteins all have the homeodomain located near the C-terminus of the protein, and also share a second conserved domain (the ELK domain) immediately N-terminal to the homeodomain. Progeny were scored for the appearance of the KNAT1 overexpression phenotype. A construct containing the KNAT3 N-terminus and the KNAT1 ELK- and homeodomain resulted in a KNAT1 overexpression phenotype, indicating that specificity mainly resides within the ELK- and homeodomain region. Further exchanges demonstrated that specificity probably does not arise from a single region within the ELK and/or homeodomain but rather requires sequences both N-terminal and C-terminal to residue 23 of the homeodomain. Further, in contrast to some animal homeodomains, KNAT1 does not utilize the residues of the N-terminal arm of the homeodomain for specificity. 相似文献
164.
165.
166.
Mapping of a Gene for Long QT Syndrome to Chromosome 4q25-27 总被引:21,自引:0,他引:21
Jean-Jacques Schott Flavien Charpentier Sophie Peltier Patrick Foley Emmanuel Drouin Jean-Brieuc Bouhour Patricia Donnelly Gilles Vergnaud Lucien Bachner Jean-Paul Moisan Herv Le Marec Olivier Pascal 《American journal of human genetics》1995,57(5):1114-1122
Long QT syndrome (LQTS) is a heterogeneous inherited disorder causing syncope and sudden death from ventricular arrhythmias. A first locus for this disorder was mapped to chromosome 11p15.5. However, locus heterogeneity has been demonstrated in several families, and two other loci have recently been located on chromosomes 7q35-36 and 3p21-24. We used linkage analysis to map the locus in a 65-member family in which LQTS was associated with more marked sinus bradycardia than usual, leading to sinus node dysfunction. Linkage to chromosome 11p15.5, 7q35-36, or 3p21-24 was excluded. Positive linkage was obtained for markers located on chromosome 4q25-27. A maximal LOD score of 7.05 was found for marker D4S402. The identification of a fourth locus for LQTS confirms its genetic heterogeneity. Locus 4q25-27 is associated with a peculiar phenotype within the LQTS entity. 相似文献
167.
168.
Ecomorphological correlates in ten species of subtropical seagrass fishes: diet and microhabitat utilization 总被引:6,自引:0,他引:6
Philip J. Motta Kari B. Clifton Patricia Hernandez Bradley T. Eggold 《Environmental Biology of Fishes》1995,44(1-3):37-60
Synopsis Ecomorphological correlates were sought among ten species of distantly related subtropical seagrass fishes. Morphometric data associated with feeding and microhabitat utilization were compared by principal components analysis, cluster analysis, and canonical correspondence analysis to dietary data. Morphology was generally a poor predictor of diet except for a group of mid-water planktotrophic filter feeders. Separation of the species along morphological axes appears to be related more to microhabitat utilization resulting in three major groups: (1) a group of planktotrophic, mid-water fishes specialized for cruising and seeking out evasive prey characterized by a compressed fusiform body, forked caudal fin, long, closely spaced gill rakers, short to intermediate! length pectoral fin, pointed pectoral fin, large lateral eye, short head, and a terminal or subterminal mouth; (2) slow swimming, less maneuverable epibenthic fishes that pick or suck their prey off the substrate. They are united by more rounded caudal and pectoral fins, and short or no gill rakers; and (3) a group of more mobile and maneuverable epibenthic foragers characterized by a more compressed, sub-gibbose body, long, pointed pectoral fins, forked caudal fins, large lateral eyes, subterminal mouth, and greater jaw protrusibility. Cases of convergence in trophic and microhabitat utilization characters were apparent in some of the groups. 相似文献
169.
Valerie Brecx Aleksandra Misicka Patricia Verheyden Dirk Tourwé George van Binst 《Letters in Peptide Science》1995,2(3-4):165-168
Summary A new cis-peptide bond mimetic, -benzyl-o-aminomethylphenylacetic acid, was synthesized and incorporated in a homodetic somatostatin analogue. Biological binding tests and 2D NMR conformational analysis indicate that the configuration of the bridge-unit asymmetric center and the orientation of the benzyl side chain play a key role in the biological activity of this type of somatostatin analogues. 相似文献
170.
John J. Malinowski Bruce L. Grasberger Gary Trakshel Edward E. Huston Tracey M. Banks Patricia G. Brake Richard B. Ciccarelli Barry N. Jones James A. Koehn Diane Kratz Nicole Lundberg Panayiotis E. Stevis Carla T. Helaszek Mark A. Ator Angela M. Small Wood Travis Stams Byron Rubin Richard S. Alexander 《Protein science : a publication of the Protein Society》1995,4(10):2149-2155