全文获取类型
收费全文 | 1246篇 |
免费 | 105篇 |
出版年
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 18篇 |
2015年 | 28篇 |
2014年 | 36篇 |
2013年 | 66篇 |
2012年 | 52篇 |
2011年 | 59篇 |
2010年 | 45篇 |
2009年 | 38篇 |
2008年 | 52篇 |
2007年 | 72篇 |
2006年 | 59篇 |
2005年 | 55篇 |
2004年 | 60篇 |
2003年 | 46篇 |
2002年 | 62篇 |
2001年 | 55篇 |
2000年 | 69篇 |
1999年 | 54篇 |
1998年 | 23篇 |
1997年 | 22篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 27篇 |
1991年 | 24篇 |
1990年 | 27篇 |
1989年 | 28篇 |
1988年 | 21篇 |
1987年 | 21篇 |
1986年 | 25篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1976年 | 4篇 |
1972年 | 4篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有1351条查询结果,搜索用时 46 毫秒
971.
Sogabe A Matsumoto K Ohashi M Watanabe A Takata H Murakami Y Omori K Yanagisawa Y 《Biology letters》2008,4(4):362-365
Syngnathid fish (pipefish and seahorses) are unique among teleost fish in that their ovary consists of a rolled sheet with germinal ridge(s) on the dorsal side running along the entire length of the sheet. A distinct difference is seen in the ovarian structure between polygamous Syngnathus pipefish and monogamous seahorses (Hippocampus spp.), the former having one germinal ridge and the latter with two ridges. This study examined the ovarian structure and the mode of egg production in a monogamous pipefish Corythoichthys haematopterus. The ovary of C. haematopterus had two germinal ridges like that observed in monogamous seahorses. There were two distinct groups of follicles in the ovary, one being a cohort of extremely small follicles and the other a cohort of follicles developing and increasing in size with the passage of time. We suggest that the ovarian structure and the mode of egg production in this pipefish are adaptations to monogamy. 相似文献
972.
973.
974.
Fetal gender determination in early pregnancy through qualitative and quantitative analysis of fetal DNA in maternal serum 总被引:28,自引:0,他引:28
Hiroshi Honda Norio Miharu Yoko Ohashi Osamu Samura Masayuki Kinutani Tetsuaki Hara Koso Ohama 《Human genetics》2002,110(1):75-79
Fetal DNA in maternal plasma and serum has been shown to be a useful material for fetal gender determination and for screening tests for abnormal pregnancies except during early gestational ages. Maternal serum samples were obtained from 81 pregnant women during the 5th-10th weeks of gestation. Fetal gender was determined by conventional polymerase chain reaction (PCR) to detect a Y-chromosomal sequence (DYS14) in maternal serum during early gestation and confirmed by examination of the newborns after delivery. Real-time quantitative analyses of the SRY and beta-globin genes were also performed in order to determine fetal gender and to quantify fetal DNA concentration in maternal serum during early gestation. When using conventional PCR, the total sensitivity of identifying a male fetus was 95%, but its sensitivity after the 7th week was 100%, whereas in real-time quantitative PCR, the total sensitivity after the 5th week was 100%. Quantitative analyses of the SRY gene revealed that the mean concentration of fetal DNA in maternal serum was 30.55 copies/ml, that fetal DNA concentration showed a tendency to increase with the progression of pregnancy, and that it had a wide normal range. Thus, we could confidently determine fetal gender by using maternal serum samples taken as early as the 7th week. 相似文献
975.
Iwatsuki K Ikeda Y Ohashi K Nakamura K Kai C 《Microbes and infection / Institut Pasteur》1999,1(12):987-991
We produced a B95a lymphoid cell line persistently infected with canine distemper virus (CDV), in which virus-specific antigens were present in nearly 100% of cells without causing cytopathic effect. The virus recovered from this cell line was able to infect fresh B95a cells persistently, indicating that a persistent CDV was established. 相似文献
976.
H Ohashi S Hashizume H Murakami K Aihara K Shinohara H Omura 《Cell biology international reports》1986,10(2):77-83
A 6-thioguanine-resistant human B-lymphoblastoid cell line, HO-323, was isolated for making human-human hybridomas with high efficiency. Fusions with peripheral blood lymphocytes of systemic lupus erythematosus (SLE) patients and lymphocytes isolated from lymph nodes of lung and breast cancer patients yield constantly more than one hybridoma clones per 10(5) HO-323 cells plated. HO323 cells also fused with lymphocytes from normal peripheral blood to give hybridomas in the same efficiency. The HO-323 cells were diploid with 46 chromosomes and non-secretors of immunoglobulins. This parent cells doubled every 15 hr and could proliferate in serum-containing medium, even if they were plated at low cell density of less than 10(3) cells/ml. The cells could grow in serum-free medium as well as in serum-containing medium, and the resultant human-human hybridomas could also grow in the same media. 相似文献
977.
Molecular cloning of the penicillin G acylase gene from Arthrobacter viscosus. 总被引:2,自引:2,他引:2 下载免费PDF全文
H Ohashi Y Katsuta T Hashizume S N Abe H Kajiura H Hattori T Kamei M Yano 《Applied microbiology》1988,54(11):2603-2607
Penicillin G acylase was purified from the cultured filtrate of Arthrobacter viscosus 8895GU and was found to consist of two distinct subunits with apparent molecular weights of 24,000 (alpha) and 60,000 (beta). The partial N-terminal amino acid sequences of the alpha and beta subunits were determined with a protein gas phase sequencer, and a 29-base oligonucleotide corresponding to the partial amino acid sequence of the alpha subunit was synthesized. An Escherichia coli transformant having the penicillin G acylase gene was isolated from an A. viscosus gene library by hybridization with the 29-base probe. The resulting positive clone was further screened by the Serratia marcescens overlay technique. E. coli carrying a plasmid designated pHYM-1 was found to produce penicillin G acylase in the cells. This plasmid had an 8.0-kilobase pair DNA fragment inserted in the EcoRI site of pACYC184. 相似文献
978.
Yamada T Ohashi Y Ohshima M Inui H Shiota N Ohkawa H Ohkawa Y 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(2-3):308-314
A gene of the enzyme involved in xenobiotic metabolism in mammalian liver was introduced into potato to confer inducible herbicide
tolerance. A rat cytochrome P450 monooxygenase, CYP1A1 cDNA, was kept under the control of the tobacco PR1a promoter in order
to apply the system of chemical inducible expression using the plant activator Benzothiadiazole (BTH). Transgenic plants were
obtained based on the kanamycin resistance test and PCR analysis. Northern-blot analysis revealed the accumulation of mRNA
corresponding to rat CYP1A1 in the transgenic plants treated with BTH (3.0 μmol/pot), whereas no accumulation of the corresponding
mRNA occurred without BTH treatment. These transgenic plants also produced a protein corresponding to CYP1A1 in the leaves
by BTH treatment. The transgenic plants with BTH application showed a much-higher tolerance to the phenylurea herbicides chlortoluron
and methabenzthiazuron than non-transgenic plants. These findings indicated that the ability of metabolizing the two herbicides
to less-toxic derivatives was displayed in the transgenic plants after BTH treatment. Transgenic plants harboring the CYP1A1
cDNA fused with the yeast P450 reductase (YR) gene under the control of PR1a were also produced. Although the plants showed
a lower expression level of the fused gene than transgenic plants with CYP1A1 cDNA alone, they were tolerant to herbicides.
These facts suggested that the CYP1A1 enzyme fused with YR showed a higher specific activity than CYP1A1 alone. This study
demonstrated that the mammalian cDNA for the de-toxification enzyme of herbicides under the control of the PR1a promoter conferred
chemical-inducible herbicide tolerance on potato.
Received: 15 March 2001 / Accepted: 14 June 2001 相似文献
979.
The acetyltransferase activity of neutrophils from patients with inflammatory disorders was assayed using the homogenate preparation of neutrophils. The enzyme activity was evaluated on both non-stimulated and stimulated neutrophils. The enzyme activity of neutrophils from 21 patients with rheumatoid arthritis and 10 patients with Behcet's disease was not significantly different from that of the control group. In contrast, it was significantly elevated in patients with bacterial infection, especially that of non-stimulated cells. The increase in the enzyme activity best correlated with the degree of fever. The elevated enzyme activity tended to normalize during convalescence. 相似文献
980.
Y Ozaki S Kume T Ohashi Y Niwa 《Biochemical and biophysical research communications》1986,134(2):690-697
Superoxide production by neutrophils induced by 1-oleoyl-2-acetyl-sn-glycerol at concentrations below 100 microM was enhanced by extracellular calcium ions, while that of phorbol myristate acetate was unaffected. Verapamil, a calcium-channel blocker, more effectively inhibited the superoxide production induced by 1-oleoyl-2-acetyl-sn-glycerol than that of phorbol myristate acetate. Cytochalasin B at 5 micrograms/ml significantly potentiated superoxide production by 1-oleoyl-2-acetyl-sn-glycerol at concentrations below 100 microM, but not that of phorbol myristate acetate. It is suggested that neutrophil activation induced by the former have different features from that of the latter. 相似文献