全文获取类型
收费全文 | 8460篇 |
免费 | 839篇 |
国内免费 | 3篇 |
出版年
2022年 | 64篇 |
2021年 | 134篇 |
2020年 | 83篇 |
2019年 | 82篇 |
2018年 | 141篇 |
2017年 | 122篇 |
2016年 | 200篇 |
2015年 | 339篇 |
2014年 | 368篇 |
2013年 | 481篇 |
2012年 | 572篇 |
2011年 | 547篇 |
2010年 | 358篇 |
2009年 | 344篇 |
2008年 | 518篇 |
2007年 | 453篇 |
2006年 | 391篇 |
2005年 | 429篇 |
2004年 | 409篇 |
2003年 | 417篇 |
2002年 | 359篇 |
2001年 | 146篇 |
2000年 | 101篇 |
1999年 | 126篇 |
1998年 | 135篇 |
1997年 | 100篇 |
1996年 | 79篇 |
1995年 | 82篇 |
1994年 | 81篇 |
1993年 | 84篇 |
1992年 | 75篇 |
1991年 | 72篇 |
1990年 | 63篇 |
1989年 | 59篇 |
1988年 | 69篇 |
1987年 | 75篇 |
1986年 | 67篇 |
1985年 | 75篇 |
1984年 | 62篇 |
1983年 | 67篇 |
1982年 | 71篇 |
1981年 | 76篇 |
1980年 | 56篇 |
1979年 | 50篇 |
1978年 | 40篇 |
1977年 | 44篇 |
1974年 | 35篇 |
1973年 | 38篇 |
1971年 | 39篇 |
1969年 | 44篇 |
排序方式: 共有9302条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Mario Penna Robert R. Capranica Jane Somers 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,170(1):73-82
Summary Twenty four castrated male, 6 intact male, and 11 intact female Hyla cinerea were injected subcutaneously with 25 g arginine-vasotocin (AVT) and induced to call 1 h later in response to the playback of a conspecific mating call. Eighteen castrated males and 8 intact females were implanted 5 mg androgen pellets for 3 weeks prior to the neuropeptide injection. Among castrated males, 6/9 testosterone (T) implanted, 4/9 dihydrotestosterone (DHT) implanted and 2/6 non implanted individuals produced calls after being administered AVT. 5/6 intact non implanted males and 6/8 T intact implanted females also called, and 3 intact non implanted females remained silent after the injection. Evoked calls had a mid-frequency spectral peak at about 1900 Hz which is absent in field-recorded mating calls of this species. Calls of implanted females and castrated non implanted males were shorter than those of castrated implanted and intact non implanted males. Audiograms measured before hormone implants showed dips of enhanced sensitivity at about 0.5, 0.9 and 3.0 kHz in males and females. After AVT injection, thresholds at frequencies within the 0.7–1.5 kHz range were increased in castrated males. Such reduction in sensitivity points to an inhibition of the auditory system during hormone induced vocal activation.Abbreviations
AVT
arginine-vasotocin
-
DHT
dihydrotestosterone
-
T
testosterone
-
TS
torus semicircularis 相似文献
55.
Mapping of genes on the linear chromosome of the bacterium Borrelia burgdorferi: Possible locations for its origin of replication 总被引:13,自引:0,他引:13
Iain G. Old Jane MacDougall Isabelle Saint Girons Barrie E. Davidson 《FEMS microbiology letters》1992,99(2-3):245-250
Molecular clones of Borrelia burgdorferi, aetiologic agent of Lyme borreliosis, were isolated and analysed by DNA sequence determination. This procedure yielded B. burgdorferi homologues of gidA, gyrB, gyrA, ftsA and ftsZ. The genes were located on the physical map of the B. burgdorferi linear chromosome. Also mapped were the genes fla and p60 while dnaA was mapped using a heterologous probe. gyrA and gyrB were found to be in tandem and were mapped, along with dnaA at the centre of the chromosome. gidA was located close to the left hand extremity of the chromosome. Because gyrB, dnaA and gidA are normally located within 50 kb of the origin of replication (oriC), we propose two possible sites for oriC in the B. burgdorferi linear chromosome. 相似文献
56.
Insertional inactivation of a gene which controls expression of vancomycin resistance on plasmid pHKK100 总被引:8,自引:0,他引:8
Sandra Handwerger Linda Discotto Jane Thanassi Michael J. Pucci 《FEMS microbiology letters》1992,92(1):11-14
Expression of inducible high level vancomycin resistance (Vmr) in enterococci appears to require other plasmid-encoded genes in addition to the previously described structural genes vanA and vanH. Tn917 mutagenesis was used to identify such a region in the Vmr plasmid pHKK100. Insertional inactivation of a 693-bp open reading frame upstream from vanH resulted in complete loss of Vmr. This putative 26,642-Da protein has been designated VanR. 相似文献
57.
58.
59.
Sarah Jane Gurr Michael J. McPherson Claire Scollan Howard J. Atkinson Dianna J. Bowles 《Molecular & general genetics : MGG》1991,226(3):361-366
Summary A major pathogen of potato plants (Solanum tuberosum) is the potato cyst nematode (Globodera spp.), which induces localized redifferentiation of a limited number of host cells to form a specialized feeding-site termed the syncytium. A novel strategy utilizing the polymerase chain reaction (PCR) was employed to construct a cDNA library from dissected potato roots highly enriched in syncytial material. The library was differentially screened with cDNA probes derived from the infected root tissue from a compatible interaction and from healthy root tissue. Characterization of one gene identified by the library screen indicated an expression pattern that correlated with events in the immediate vicinity of the pathogen after syncytial establishment. The strategy for library construction and screening could be applicable to the study of gene expression in any plant-pathogen interaction in which the limited supply of cells at the interface of the two organisms precludes a more traditional approach. 相似文献
60.