全文获取类型
收费全文 | 5519篇 |
免费 | 549篇 |
国内免费 | 8篇 |
出版年
2022年 | 37篇 |
2021年 | 81篇 |
2020年 | 36篇 |
2019年 | 57篇 |
2018年 | 85篇 |
2017年 | 61篇 |
2016年 | 116篇 |
2015年 | 147篇 |
2014年 | 201篇 |
2013年 | 245篇 |
2012年 | 316篇 |
2011年 | 309篇 |
2010年 | 234篇 |
2009年 | 170篇 |
2008年 | 313篇 |
2007年 | 290篇 |
2006年 | 205篇 |
2005年 | 230篇 |
2004年 | 221篇 |
2003年 | 209篇 |
2002年 | 198篇 |
2001年 | 109篇 |
2000年 | 95篇 |
1999年 | 99篇 |
1998年 | 74篇 |
1997年 | 62篇 |
1996年 | 64篇 |
1995年 | 59篇 |
1994年 | 45篇 |
1993年 | 57篇 |
1992年 | 94篇 |
1991年 | 91篇 |
1990年 | 79篇 |
1989年 | 78篇 |
1988年 | 87篇 |
1987年 | 67篇 |
1986年 | 62篇 |
1985年 | 58篇 |
1984年 | 70篇 |
1983年 | 57篇 |
1982年 | 45篇 |
1981年 | 45篇 |
1980年 | 61篇 |
1979年 | 52篇 |
1978年 | 56篇 |
1977年 | 42篇 |
1976年 | 54篇 |
1975年 | 45篇 |
1974年 | 38篇 |
1973年 | 51篇 |
排序方式: 共有6076条查询结果,搜索用时 31 毫秒
41.
S Daniels-McQueen A Ray W E Walden B K Ray P H Brown R E Thach 《Nucleic acids research》1988,16(15):7741
42.
43.
44.
45.
Summary The inheritance of both the mitochondrial DNA (mtDNA) and the nuclear-encoded extrachromosomal ribosomal DNA (rDNA) has been studied in the myxomycete, Didymium iridis, by DNA-DNA hybridization of labeled probes to total DNA at various stage of the life cycle. Both the mtDNA and rDNA populations rapidly become homogeneous in individuals, but there is a qualitative difference in the patterns of inheritance of these two molecules. One parental rDNA type was preferentially inherited in all crosses; selective replication of this molecule is tentatively proposed as the mechanism of inheritance. In contrast, either parental mtDNA type could be inherited. Since the inherited population of parental mtDNA molecules are not partitioned into cells in this coenocytic organism, no known mechanism of inheritance can explain the rapid and apparently random loss of one parental mtDNA type in individuals. 相似文献
46.
47.
Peter O''Connell G. Mark Lathrop Mark Leppert Yusuke Nakamura Ulrich Müller Jean-Marc Lalouel Ray White 《Genomics》1988,3(4):367-372
We have constructed a primary genetic map of human chromosome 18 consisting of 11 DNA markers and one serological marker (JK). Two of these loci define highly polymorphic VNTR systems. The markers define a continuous genetic linkage map of 97 cM in males and 205 cM in females; female genetic distances in a panel of 59 three-generation families were consistently about twice those observed in males. The high odds in support of the linear order of the markers on this recombination map, and the extent of coverage of chromosome 18, indicate that this map will permit efficient linkage studies of human genetic diseases that may be segregating on chromosome 18 and will provide anchor points for development of high-resolution maps for this chromosome. 相似文献
48.
Sixty-nine strains of bacteria isolated from murcha and ragi (amylase starters) were studied. These came from 14 different amylase starters from Java, Bali, and Nepal and were isolated from dilution plates incubated under aerobic and anaerobic conditions. Most belonged to Pediococcus , probably P. pentosaceus , and to Streptococcus faecalis. None were able to attack starch although they are used in starch fermentations. When inoculated on rice as pure cultures most of them failed to show visible growth unless yeasts and moulds were added at the same time. The roles of these bacteria are unknown but they may produce secondary products from the glucose formed by the amylolytic yeasts and moulds always found in the starters. 相似文献
49.
Immunization of mice with a synthetic GM3-lactam-BSA (bovine serum albumin) conjugate (designed to emulate the corresponding natural GM3-lactone conjugate), followed by fusion of splenocytes with myeloma cells, gave rise to more than 300 monoclonal hybridomas producing antibodies to GM3-lactam-BSA, which did not react with Glc-BSA and BSA. Eight antibody clones were randomly chosen from the positive 300 hybridomas. The eight clones, all belonging to the IgG class, were unreactive against GM3-ganglioside, whereas two antibodies (P5-1 and P5-3, both IgG1, ) reacted with GM3-ganglioside lactone. Binding of these two antibodies to the GM3-lactam-BSA conjugate was inhibited by soluble glycosides of GM2-, GM3-, and GM4-lactam and by GM3- and GM4-lactam, respectively, but not by Gb3 or asialo-GM1 and GM2-saccharides. A third antibody (P3; IgG2b, ) was inhibited by GM2-, GM3-, and GM4-lactam, but did not recognize GM3-ganglioside lactone. 相似文献
50.
Christopher S. Colwell Sat Bir S. Khalsa Gene D. Block 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,170(2):211-215
Summary The eye of the marine mollusk Aplysia californica contains a photo-entrainable circadian pacemaker that drives an overt circadian rhythm of spontaneous compound action potentials in the optic nerve. Both light and serotonin are known to influence the phase of this ocular rhythm. The current study evaluated the effect of FMRFamide on both light and serotonin induced phase shifts of this rhythm. The application of FMRFamide was found to block serotonin induced phase shifts but, by itself, FMRFamide did not cause significant phase shifts. Furthermore, the effects of FMRFamide on light-induced phase shifts appeared to be phase dependent (i.e., the application of FMRFamide inhibited light-induced phase delays but actually enhanced the magnitude of phase advances). As in Aplysia, the eye of Bulla gouldiana also contains a circadian pacemaker. In Bulla, FMRFamide prevented light-induced phase advances and delays. Although FMRFamide alone generated phase dependent phase shifts, it did not cause phase shifts at the phases where it blocked the effects of light. These data demonstrate that FMRFamide can have pronounced modulatory effects on phase shifting inputs to the ocular pacemakers of both Aplysia and Bulla.Abbreviations
ASW
artificial seawater
-
CAP
compound action potential
-
CT
circadian time
-
5-HT
serotonin 相似文献