全文获取类型
收费全文 | 687篇 |
免费 | 49篇 |
专业分类
736篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 17篇 |
2017年 | 5篇 |
2016年 | 15篇 |
2015年 | 28篇 |
2014年 | 20篇 |
2013年 | 49篇 |
2012年 | 51篇 |
2011年 | 51篇 |
2010年 | 23篇 |
2009年 | 25篇 |
2008年 | 35篇 |
2007年 | 32篇 |
2006年 | 44篇 |
2005年 | 46篇 |
2004年 | 37篇 |
2003年 | 47篇 |
2002年 | 41篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1967年 | 4篇 |
1965年 | 1篇 |
排序方式: 共有736条查询结果,搜索用时 9 毫秒
11.
12.
Yukie Takahashi Masako Sohnaka Minoru Nakao Kenji Miyamoto Masahito Fukunaga 《Microbiology and immunology》1993,37(9):721-727
Thirty-two Borrelia isolates were obtained from the adult stage of ixodid ticks, Ixodes ovatus, collected in various localities in Japan. Borrelial isolates were cultivated and analyzed by polyacrylamide gel electrophoresis, with monoclonal antibodies, by pulsed field gel electrophoresis, and by genomic Southern hybridization. All borrelial isolates showed similar protein profiles and monoclonal antibody reactivities, while plasmid profiles were rather diverse. Genomic hybridization using rRNA gene probes demonstrated the genetic similarities of those isolates. We found no significant differences among the borrelial isolates tested, and the restriction fragment length polymorphism patterns of I. ovatus isolates were quite distinct from those of borrelial strains associated with Lyme disease. Therefore, the isolates of Borrelia obtained from I. ovatus were thought to fall into different genospecies. 相似文献
13.
The holotype of a bothid flounder,Arnoglossus tapeinosomus (Bleeker, 1866), was re-examined and found to bear none of the diagnostic characters ascribed by many authors to the species.
In addition, the shape of the prevomer was clearly different between the holotype and 18 specimens supposedly“A. tapeinosomus.” A. macrolophus Alcock, 1889, which was synonymized underA. tapeinosomus by Weber and de Beaufort (1929), is considered as a valid replacement name for“A. tapeinosomus,” because of the elongated anterior rays in the dorsal fin and a large, dark spot on the posterior dorsal and anal fin bases.A. tapeinosomus is redescribed from the holotype. 相似文献
14.
The flagellin gene of Borrelia miyamotoi sp. nov. and its phylogenetic relationship among Borrelia species 总被引:1,自引:0,他引:1
Abstract We have cloned and sequenced the flagellin gene from Borrelia miyamotoi strain HT31 and compared it with previously published flagellin sequences. Sequence similarity analysis demonstrated that strain HT31 is phylogenetically distant from the three species of Lyme disease borreliae and is deeply branched into the relapsing fever borrelia cluster. The result was in full agreement with the classification of Borrelia strains using 16S rRNA sequences. This finding indicates that a phylogenetic analysis using flagellin gene sequences might be useful for classification of Borrelia strains. 相似文献
15.
Shin Aizawa† Ichita Amaki Takeshi Miyanomae† Masahito Tsurusawa† Kazuhiro J. Mori† 《Cell proliferation》1984,17(2):145-152
ABSTRACT Supernatants of murine bone-marrow cultures contain a colony-promoting factor (CPF) which increases the number of granulocyte and macrophage colonies in semi-solid agar cultures in the presence of colony-stimulating factor (CSF). Incubation of bone-marrow cells with CPF results in an increase in the number of granulocyte/macrophage progenitor cells (CFU-c) and the CPF-responsive cells may be younger than the CFU-c. We have investigated the radiosensitivity and the pattern of the recovery after irradiation of CPF-responsive cells. We found that the radiosensitivity of CPF-responsive cells was significantly lower than those of CFU-c. burst-forming units-erythroid (BFU-e) and pluripotent stem cells in vivo (CFU-s) and in vitro (CFU-mix). the CPF-responsive cells remained subnormal even at 28 days after irradiation of the mice, a time when the CFU-s and CFU-c had recovered completely. Therefore the CPF-responsive cells may constitute a separate compartment, namely ‘pre-CFU-c’, in the maturation sequence of granulopoiesis, and this maturation of the ‘pre-CFU-c’ to CFU-c seems to be highly stimulated after irradiation to counterbalance the influx from CFU-s. 相似文献
16.
Negative ion fast atom bombardment-tandem mass spectrometry for structural analysis of isoprenoid diphosphates 总被引:1,自引:0,他引:1
M Kitaoka H Nagaki T Kinoshita M Kurabayashi T Koyama K Ogura 《Analytical biochemistry》1990,185(1):182-186
Applicability of negative ion fast atom bombardment (FAB)-tandem mass spectrometry (MS/MS) was examined in trace mixture analyses and structural assignments of some isoprenoid diphosphates. Negative ion FAB-MS spectra using a glycerol matrix of these isoprenoid diphosphates showed predominantly molecular ions (M-H)- together with fragment ions at m/z 177 (H3P2O7)-, 176 (H2P2O7)-, 159 (HP2O6)-, and 79 (PO3)- which were characteristic of the diphosphate ester moiety. The molecular ions did not overlap with peaks arising from any impurities even when crude sample such as butanol extracts from enzymatic reaction mixtures were directly analyzed without any purification. Moreover, collisionally activated dissociation spectra of the molecular ion showed many structurally significant fragment ions which enabled us to elucidate the structures of such irregular alkyl chain moieties as those having a homoisoprenoid skeleton or substituted structures. These studies indicate that negative ion FAB-MS/MS is a simple and useful technique for trace mixture analysis and structure elucidation of isoprenoid diphosphates. 相似文献
17.
F Taguchi D Nagaki M Saito C Haruyama K Iwasaki 《Japanese journal of microbiology》1975,19(5):395-398
The prevalance and distribution of BK virus antibody in women during pregnancy and the occurrence of transplacental transmission of BK virus was determined by measurement of IgM antibody in the serum. Sera were collected from 63 nonpregnant women, 71 women who had experienced spontaneous abortion, 80 in the first trimester of pregnancy and the same 80 at delivery. Umbilical cord blood was also taken at delivery. Hemagglutination inhibition (HI) tests for BK virus used the micromethod of Gardner. Results indicate that a significant level of HI antibody was present in 70% of sera from all 4 experimental groups. This showed that BK virus infection was not limited to cases of spontaneous abortion. Of the 80 pregnant mothers, 6 showed a 4-fold or greater HI antibody seroconversion to BK virus after delivery. Of these 6 seroconversion patients, sensitive antibody was detected in 3 umbilical cords. Umbilical cords of those without seroconversion had no sensitive antibody. As evidenced by 2-NE-sensitive antibody, BK virus infections were also recognized in 6 of 71 women who aborted, 4 of 80 in the first trimester of pregnancy and 2 collected after delivery. The 2-ME-sensitive antibody was not found in any of 63 samples from nonpregnant women. Data indicate that 2-ME-sensitive antibody was present only in sera of women during pregnancy and after abortion. It may be possible that BK virus persists in a latent form in many healthy women and becomes activated during pregnancy. 相似文献
18.
Seiya Oura Toshiaki Hino Takashi Satoh Taichi Noda Takayuki Koyano Ayako Isotani Makoto Matsuyama Shizuo Akira Kei-ichiro Ishiguro Masahito Ikawa 《PLoS genetics》2022,18(6)
Meiosis is a hallmark event in germ cell development that accompanies sequential events executed by numerous molecules. Therefore, characterization of these factors is one of the best strategies to clarify the mechanism of meiosis. Here, we report tripartite motif-containing 41 (TRIM41), a ubiquitin ligase E3, as an essential factor for proper meiotic progression and fertility in male mice. Trim41 knockout (KO) spermatocytes exhibited synaptonemal complex protein 3 (SYCP3) overloading, especially on the X chromosome. Furthermore, mutant mice lacking the RING domain of TRIM41, required for the ubiquitin ligase E3 activity, phenocopied Trim41 KO mice. We then examined the behavior of mutant TRIM41 (ΔRING-TRIM41) and found that ΔRING-TRIM41 accumulated on the chromosome axes with overloaded SYCP3. This result suggested that TRIM41 exerts its function on the chromosome axes. Our study revealed that Trim41 is essential for preventing SYCP3 overloading, suggesting a TRIM41-mediated mechanism for regulating chromosome axis protein dynamics during male meiotic progression. 相似文献
19.
Masahito Tsuboi Jun Shoji Atsushi Sogabe Ingrid Ahnesjö Niclas Kolm 《Ecology and evolution》2016,6(3):647-655
The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the high cost of brain development and maintenance is predicted to constrain adaptive brain size evolution (the expensive tissue hypothesis, ETH). Here, we test the ETH in a teleost fish with predominant female mating competition (reversed sex roles) and male pregnancy, the pacific seaweed pipefish Syngnathus schlegeli. The relative size of the brain and other energetically expensive organs (kidney, liver, heart, gut, visceral fat, and ovary/testis) was compared among three groups: pregnant males, nonpregnant males and egg producing females. Brood size in pregnant males was unrelated to brain size or the size of any other organ, whereas positive relationships were found between ovary size, kidney size, and liver size in females. Moreover, we found that the size of energetically expensive organs (brain, heart, gut, kidney, and liver) as well as the amount of visceral fat did not differ between pregnant and nonpregnant males. However, we found marked differences in relative size of the expensive organs between sexes. Females had larger liver and kidney than males, whereas males stored more visceral fat than females. Furthermore, in females we found a negative correlation between brain size and the amount of visceral fat, whereas in males, a positive trend between brain size and both liver and heart size was found. These results suggest that, while the majority of variation in the size of various expensive organs in this species likely reflects that individuals in good condition can afford to allocate resources to several organs, the cost of the expensive brain was visible in the visceral fat content of females, possibly due to the high costs associated with female egg production. 相似文献
20.
Yuka Okada Yuko Ueshin Hidetoshi Hasuwa Kazuhiro Takumi Masaru Okabe Masahito Ikawa 《Genesis (New York, N.Y. : 2000)》2009,47(4):217-223
Lentiviral vectors efficiently integrate into the host genome of both dividing and nondividing cells, and so they have been used for stable transgene expression in biological and biomedical studies. However, recent studies have highlighted the risk of insertional mutagenesis and subsequent oncogenesis. Here, we used an integrase‐defective lentiviral (IDLV) vector to decrease the chance of random integration and examined the feasibility of lentiviral vector‐mediated gene targeting into murine embryonic stem (ES) cells. After transduction with wild‐type lentiviral vectors, none of the 512 G418 resistant clones were found to be homologous recombinant clones. Although the transduction efficiency was lower with the IDLV vectors (5.9% of wild‐type), successful homologous recombination was observed in nine out of the 941 G418 resistant clones (0.83 ± 1.32%). Pluripotency of the homologous recombinant ES cells was confirmed by the production of chimeric mice and subsequent germ line transmission. Because lentiviral vectors can efficiently transduce a variety of stem cell types, our strategy has potential relevance for secure gene‐manipulation in therapeutic applications. genesis 47:217–223, 2009. © 2009 Wiley‐Liss, Inc. 相似文献