全文获取类型
收费全文 | 3864篇 |
免费 | 234篇 |
出版年
2022年 | 20篇 |
2021年 | 46篇 |
2020年 | 32篇 |
2019年 | 42篇 |
2018年 | 54篇 |
2017年 | 42篇 |
2016年 | 71篇 |
2015年 | 103篇 |
2014年 | 132篇 |
2013年 | 260篇 |
2012年 | 195篇 |
2011年 | 240篇 |
2010年 | 137篇 |
2009年 | 130篇 |
2008年 | 198篇 |
2007年 | 173篇 |
2006年 | 191篇 |
2005年 | 154篇 |
2004年 | 182篇 |
2003年 | 190篇 |
2002年 | 169篇 |
2001年 | 118篇 |
2000年 | 142篇 |
1999年 | 108篇 |
1998年 | 66篇 |
1997年 | 46篇 |
1996年 | 42篇 |
1995年 | 38篇 |
1994年 | 31篇 |
1993年 | 33篇 |
1992年 | 59篇 |
1991年 | 61篇 |
1990年 | 49篇 |
1989年 | 58篇 |
1988年 | 58篇 |
1987年 | 36篇 |
1986年 | 38篇 |
1985年 | 48篇 |
1984年 | 24篇 |
1983年 | 24篇 |
1982年 | 19篇 |
1981年 | 21篇 |
1980年 | 18篇 |
1979年 | 13篇 |
1978年 | 19篇 |
1977年 | 24篇 |
1976年 | 13篇 |
1975年 | 24篇 |
1974年 | 16篇 |
1973年 | 28篇 |
排序方式: 共有4098条查询结果,搜索用时 15 毫秒
41.
T. Kageoka C. Satoh K. Goriki M. Fujita S. Neriishi K. Yamamura J. Kaneko N. Masunari 《Human genetics》1985,70(2):101-108
Summary Electrophoretic screening of glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6PD) was conducted one sample of 9,260 children born to the atomic bomb survivors in Hiroshima (Honshu) and Nagasaki (Kyushu). The prevalence of electrophoretic variants was 0.11% in males and 0.42% in females in Hiroshima, and 0.16% in males and 0.31% in females in Nagasaki. Enzymologic characteristics of 10 variants obtained from three males and seven hemizygous fathers of heterozygous females were examined. As a result, three new types of G6PD variants were identified among five variants detected in Hiroshima, and three new types among five variants in Nagasaki. All the variants except one belonged to Class 3, as defined by Yoshida et al. (1971). 相似文献
42.
Restriction endonucleases (13 out of 18 species used for the test) were certified to cleave single-stranded(ss)DNA. Such enzymes as AvaII, HaeII, DdeI, AluI, Sau3AI, AccII,TthHB8I and HapII were newly reported to cleave ssDNA. A model to account for the cleavage of ssDNA by restriction enzymes was proposed with supportive data. The essential part of the model was that restriction enzymes preferentially cleave transiently formed secondary structures (called canonical structures) in ssDNA composed of two recognition sequences with two fold rotational symmetry. This means that a restriction enzyme can cleave ssDNAs in general so far as the DNAs have the sequences of restriction sites for the enzyme, and that the rate of cleavage depends on the stabilities of canonical structures. 相似文献
43.
Purification and characterization of two kinds of porins from the Enterobacter cloacae outer membrane. 总被引:5,自引:0,他引:5 下载免费PDF全文
Two major outer membrane proteins of Enterobacter cloacae 206 were purified and identified as porins by using reconstituted vesicles. The 37-kilodalton porin forms a channel with a radius of 0.6 nm, which prefers positively charged substances to negatively charged ones, whereas the 39- to 40-kilodalton porin forms a larger channel with a radius of 0.8 nm, which has weaker selectivity for electric charges. 相似文献
44.
A newly designed Y-shaped box was previously reported by authors to be useful for a screening test of visual abnormality in rats because of easy numerization and statistical analysis of the results. In the present paper, the relationship between the intensity of illumination and the negative phototaxic response were examined. The total selection rate for the dark area (total time of selecting dark area/total trials) of non-treated rats under 30 lux illumination was 98% and identical wit the result of those under 1600 lux. The selecting rates of non-treated rats under the illumination of 15, 10, 7.5, 5 and 1.25 lux were 95, 93, 89, 82 and 67%, respectively. On the other hand those of dark-adapted rats one hour under 15, 7.5 and 5 lux showed 98, 95 and 92%, respectively. From these results, the critical intensities of illumination-unaffected selection rate for darkness in non-treated and dark-adapted rats were estimated at 30 and 15 lux, respectively. There was an obvious effect of dark-adaptation on the visual ability of rats. The selection rate of eyelid-sutured rats under 30 lux was 52%, an approximate theoretical value of true blindness, but it was 85% under 1600 lux. It is suggested that a more exact detection of visual abnormality would be possible under the critical intensity of illumination-unaffected selection rate for darkness. 相似文献
45.
M Kaneko 《Mutation research》1984,131(3-4):157-161
The rate of removal of DNA adducts of several benzo[a]pyrene metabolites from nuclear DNA was compared by introducing a microsome-activating system in human fibroblast cells. Confluent human fibroblasts were exposed to benzo[a]pyrene in the presence of a microsomal activating system and DNA adducts were formed in the nuclear DNA. The adducts present in DNA were determined after 1 h of incubation and 48 h later. There was no difference in the rate of removal between 7S- and 7R -N2-[10-(7 beta, 8 alpha-trihydroxy-7,8,9,10- tetrahydrobenzo[a]pyrene)yl]deoxyguanosine, 7R -N2-[10(7beta, 8 alpha, 9 beta-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene)yl]deoxyguanosine and the covalent adduct of 9-hydroxybenzo[a]pyrene-4,5-epoxide to guanosine. This finding does not agree with the idea that metabolites forming 'persistent DNA adducts' are always responsible for the carcinogenicity of their parent compound. 相似文献
46.
Oncogene amplification in tumor cells 总被引:1,自引:0,他引:1
N Kanda Y Kaneko Y Hayashi T Utakoji 《Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme》1986,31(13):1277-1285
47.
A new class of site-specific endodeoxyribonucleases. Endo.Sce I isolated from a eukaryote, Saccharomyces cerevisiae 总被引:6,自引:0,他引:6
H Watabe T Iino T Kaneko T Shibata T Ando 《The Journal of biological chemistry》1983,258(8):4663-4665
We had found that yeasts had intracellular endodeoxyribonucleases that cut phage DNA into a set of double-stranded fragments with discrete chain lengths. We purified one of them to apparent homogeneity from Saccharomyces cerevisiae and designated it Endo.Sce I. Sequence analysis around 5 cleavage sites in plasmid DNA and phage DNA revealed that Endo.Sce I cuts a defined phosphodiester bond in each strand of double helix at the cleavage sites and produces free cohesive ends consisting of 4 nucleotides protruding at 3'-termini. However, unlike in the case of prokaryotic type II-restriction endonucleases, (i) Endo.Sce I seems to consist of two nonidentical subunits, (ii) no common palindrome or consensus sequence including more than 5 base pairs is detected at or near these cleavage sites, and (iii) Endo.Sce I can cut the DNA isolated from the cells that produced Endo.Sce I. All of the 5 cleavage sites are included in inverted repeats, but these inverted repeats are variable in size, nucleotide sequence, and distance between repeating units. An inverted repeat itself is not a structure recognized by Endo.Sce I. This study shows that Endo.Sce I is the first example of eukaryotic site-specific endonuclease and has properties, as described above, which distinguish it from prokaryotic restriction endonucleases. 相似文献
48.
Masanori Kasahara Toshinao Takenouchi Kazumasa Ogasawara Hitoshi Ikeda Tsuguyo Okuyama Naoshi Ishikawa Junko Moriuchi Akemi Wakisaka Yuko Kikuchi Miki Aizawa Takehisa Kaneko Noboru Kashiwagi Yasuharu Nishimura Takehiko Sasazuki 《Immunogenetics》1983,17(5):485-495
To study the gene products of the HLA complex, we produced two monoclonal antibodies, termed HU-18 and HU-23. They were active in complement-dependent cytotoxicity and detected B-cell alloantigens encoded by a locus (or loci) linked to HLA. When three types of HLA-DR4 homozygous B-cell lines with different HLA-D specificities were tested for reactivity with HU-18 and HU-23, they displayed distinct reaction patterns depending on the HLA-D specificities they possessed: EBV-Wa (HLA-DYT homozygous), negative for both HU-18 and HU-23; KT2 and KOB (HLA-DKT2 homozygous), positive only for HU-18; and ER (HLA-Dw4 homozygous), positive for both. These differential reaction patterns were further confirmed by testing against a panel of 17 HLA-DR4-positive peripheral blood lymphocytes with known HLA-D specificities. Thus, these monoclonal antibodies allow us to identify HLA-DYT, HLA-DKT2, and HLA-Dw4 solely by serologic methods. This is the first clearcut serologic identification of these three HLA-DR4-associated HLA-D specificities, which have been indistinguishable by conventional serology and identified only by cellular techniques. It is hoped that immunochemical investigations using HU-18 and HU-23 will advance our understanding of the HLA-D region on a molecular level. 相似文献
49.
50.