全文获取类型
收费全文 | 2913篇 |
免费 | 191篇 |
出版年
2023年 | 11篇 |
2022年 | 14篇 |
2021年 | 44篇 |
2020年 | 21篇 |
2019年 | 26篇 |
2018年 | 36篇 |
2017年 | 40篇 |
2016年 | 68篇 |
2015年 | 104篇 |
2014年 | 116篇 |
2013年 | 168篇 |
2012年 | 181篇 |
2011年 | 173篇 |
2010年 | 109篇 |
2009年 | 122篇 |
2008年 | 179篇 |
2007年 | 175篇 |
2006年 | 188篇 |
2005年 | 165篇 |
2004年 | 158篇 |
2003年 | 152篇 |
2002年 | 120篇 |
2001年 | 65篇 |
2000年 | 60篇 |
1999年 | 64篇 |
1998年 | 25篇 |
1997年 | 29篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 21篇 |
1993年 | 21篇 |
1992年 | 43篇 |
1991年 | 50篇 |
1990年 | 31篇 |
1989年 | 32篇 |
1988年 | 25篇 |
1987年 | 24篇 |
1986年 | 28篇 |
1985年 | 22篇 |
1984年 | 23篇 |
1983年 | 22篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1978年 | 6篇 |
1977年 | 13篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1974年 | 9篇 |
1973年 | 7篇 |
1968年 | 5篇 |
排序方式: 共有3104条查询结果,搜索用时 283 毫秒
41.
Naoyuki Miyashita Yoshifumi Kubota Masashi Kimura Masamitsu Nakajima Yoshihito Niki Rinzo Soejima Akira Matsumoto 《Microbiology and immunology》1994,38(11):857-864
The isolation of Chlamydia pneumoniae, especially from elderly persons, is generally not easy. Recently, we succeeded in isolating a chlamydial strain, which was designated KKpn-15, from a 57-year-old man suffering from acute bronchitis. It was compared with well established strains of C. pneumoniae, C. trachomatis and C. psittaci, and its biological properties, such as the morphology of elementary bodies (EBs) and inclusions, and the immunochemistry of EB proteins, were investigated. Based on the results obtained in the present study, it was confirmed that the new chlamydial strain, KKpn-15, is a member of the C. pneumoniae strain and that the organisms of KKpn-15 are useful as an antigen for the serodiagnosis and epidemiology of C. pneumoniae infection. 相似文献
42.
Serum-free culture of rat keratinocytes 总被引:2,自引:0,他引:2
Hirosuke Oku Chikara Kumamoto Tomoyuki Miyagi Takanori Hiyane Junichi Nagata Isao Chinen 《In vitro cellular & developmental biology. Animal》1994,30(8):496-503
Summary Procedures for the serum-free culture of rat keratinocytes have been established. Basal cells prepared from epidermis of newborn
rat were stored in liquid nitrogen and used for primary culture. Among the available media, MCDB 153, developed originally
for human keratinocyte (HK) culture, was the best for the development of serum-free formulation. To grow rat keratinocytes,
bovine serum albumin was arbitrarily substituted for the macromolecule supplements needed for HK culture, i.e. fetal bovine
serum protein or bovine pituitary extract. Qualitative and quantitative adjustment of supplements was thereafter made to support
rapid cell growth. Satisfactory cell growth was achieved in the optimized medium of MCDB 153 supplemented with growth factors
and amino acids: insulin (10 μg/ml), hydrocortisone (0.1 μg/ml), epidermal growth factor (25 ng/ml), calcium chloride (0.2
mM), histidine (0.23 mM), isoleucine (0.05 mM), tryptophane (0.015 mM), threonine (1.25 mM), tyrosine (0.031 mM), alanine (4.08 mM), and albumin (2 mg/ml). This optimized culture system was superior to the original HK culture condition for rapid growth
of rat keratinocytes. Under our condition, cells grew as a monolayer, becoming confluent, but without stratification, and
were passaged 2 to 3 times without any changes in morphology. The serum-free formulation allows us to control more accurately
the concentrations of biomolecules in the medium including lipids and hormones, and therefore will be suitable for the study
focusing on lipid metabolism or hormonal regulation of rat keratinocytes. 相似文献
43.
K. Ogawa-Goto Y. Ohta K. Kubota N. Funamoto T. Abe T. Taki K. Nagashima† 《Journal of neurochemistry》1993,61(4):1398-1403
Abstract: Compositions of neutral and sulfated glucuronyl glycosphingolipids purified from human motor and sensory nerves and myelins were studied. Higher neutral glycosphingolipids (fraction B), which were separated from GazlCer (fraction A), were analyzed by TLC and TLC-immunostaining. Both nerve myelins contained paragloboside (nLc4 Cer) and nLc6 Cer dominantly as major higher glycosphingolipids and very little globoside (Gb4 Cer), whereas both nerves contained Gb4 Cer and nLc4 Cer. Besides these major glycosphingolipids, a neutral glycolipid containing asialoGMI (Gg4 Cer) epitope and other minor components such as ceramide trihexoside and ceramide dihexoside were detected in both nerves and their myelins. Furthermore, sulfated glucuronyl nLc4 Cer and n Lc6 Cer, which were monoclonal antibody HNK-1 reactive glycolipids, were detected in both nerves and myelins. 相似文献
44.
Shuhei Takatsuka Takeshi Kubota Yuta Kurashina Sho Kurihara Motoki Hirabayashi Masato Fujioka Hirotaka James Okano Hiroaki Onoe 《Biotechnology and bioengineering》2023,120(8):2371-2377
Adeno-associated virus (AAV)-based gene therapy holds promise as a fundamental treatment for genetic disorders. For clinical applications, it is necessary to control AAV release timing to avoid an immune response to AAV. Here we propose an ultrasound (US)-triggered on-demand AAV release system using alginate hydrogel microbeads (AHMs) with a release enhancer. By using a centrifuge-based microdroplet shooting device, the AHMs encapsulating AAV with tungsten microparticles (W-MPs) are fabricated. Since W-MPs work as release enhancers, the AHMs have high sensitivity to the US with localized variation in acoustic impedance for improving the release of AAV. Furthermore, AHMs were coated with poly-l -lysine (PLL) to adjust the release of AAV. By applying US to the AAV encapsulating AHMs with W-MPs, the AAV was released on demand, and gene transfection to cells by AAV was confirmed without loss of AAV activity. This proposed US-triggered AAV release system expands methodological possibilities in gene therapy. 相似文献
45.
Hiroshi Suemizu Chika Kito-Maruyama Yusuke Sotomaru Tomoyuki Ogura Kyoji Hioki Yasuyuki Ohnishi Norikazu Tamaoki 《Experimental Animals》2004,53(5):463-466
In short-term carcinogenicity testing using CB6F1-TgrasH2 mice, sibling nonTgrasH2 mice are used as a negative control. However, selection of TgrasH2 and nonTgrasH2 mice has been performed by PCR with only transgene specific primers by the conventional method. Therefore, the conventional method involves the risk of false negative results due to reaction failure, and contamination with TgrasH2 mice in the control mice group. Based on the nucleotide sequence information around the pre-integration site, we developed a genotyping method for distinguishing not only TgrasH2 mice (hemizygous for the Tg allele) but also nonTgrasH2 (homozygous for the nonTg allele) in a positive manner. 相似文献
46.
Molecular cloning of a novel mitogen-inducible nuclear protein with a Ran GTPase-activating domain that affects cell cycle progression. 总被引:8,自引:2,他引:6 下载免费PDF全文
M Hattori N Tsukamoto M S Nur-e-Kamal B Rubinfeld K Iwai H Kubota H Maruta N Minato 《Molecular and cellular biology》1995,15(1):552-560
We have cloned a novel cDNA (Spa-1) which is little expressed in the quiescent state but induced in the interleukin 2-stimulated cycling state of an interleukin 2-responsive murine lymphoid cell line by differential hybridization. Spa-1 mRNA (3.5 kb) was induced in normal lymphocytes following various types of mitogenic stimulation. In normal organs it is preferentially expressed in both fetal and adult lymphohematopoietic tissues. A Spa-1-encoded protein of 68 kDa is localized mostly in the nucleus. Its N-terminal domain is highly homologous to a human Rap1 GTPase-activating protein (GAP), and a fusion protein of this domain (SpanN) indeed exhibited GAP activity for Rap1/Rsr1 but not for Ras or Rho in vitro. Unlike the human Rap1 GAP, however, SpanN also exhibited GAP activity for Ran, so far the only known Ras-related GTPase in the nucleus. In the presence of serum, stable Spa-1 cDNA transfectants of NIH 3T3 cells (NIH/Spa-1) hardly overexpressed Spa-1 (p68), and they grew as normally as did the parental cells. When NIH/Spa-1 cells were serum starved to be arrested in the G1/G0 phase of the cell cycle, however, they, unlike the control cells, exhibited progressive Spa-1 p68 accumulation, and following the addition of serum they showed cell death resembling mitotic catastrophes of the S phase during cell cycle progression. The results indicate that the novel nuclear protein Spa-1, with a potentially active Ran GAP domain, severely hampers the mitogen-induced cell cycle progression when abnormally and/or prematurely expressed. Functions of the Spa-1 protein and its regulation are discussed in the context of its possible interaction with the Ran/RCC-1 system, which is involved in the coordinated nuclear functions, including cell division. 相似文献
47.
Tadashi II Masayuki Kubota Takashi Hirano Mamoru Ohashi Keiichi Yoshida Sakaru Suzuki 《Glycoconjugate journal》1995,12(3):282-289
The fast atom bombardment (FAB) collision induced dissociation (CID)-mass spectrometry/mass spectrometry (MS/MS) technique was successfully applied to characterize and identify the structures of the immunoreactive trisulfated and tetrasulfated tetrasaccharides that were obtained from the chondroitin sulfate in a shark fin using a treatment with chondroitinase ABC.Abbreviations FABMS
fast atom bombardment mass spectrometry
- CID
collision induced dissociation
- MS/MS
mass spectrometry/mass spectrometry
- UA2S-GalNAc6S
2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-galactose
- UA-GalNAc4S
2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4-O-sulfo-d-galactose
- UA-GalNAcDiS
2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4,6-di-O-sulfo-d-galactose 相似文献
48.
Rat erythrocyte phosphatidylethanolamine (PE) consists of 60% alkenylacyl, 5% alkylacyl and 35% diacyl types. The fatty acid at the 2-position of these types is mainly composed of arachidonic acid. When intact rat erythrocytes were incubated with exogenous arachidonic acid, about 90% of the arachidonic acid incorporated into the PE fraction was found in the 2-position of the diacyl type. The rates of incorporation of arachidonic acid into alkenylacyl-, alkylacyl- and diacylPE were 78, 134 and 1360 pmol/h per mumol of the corresponding PE, respectively. The substrate specificities of endogenous phospholipase A2 and acyl-CoA:lysophospholipid acyltransferase were observed. DiacylPE was hydrolysed rapidly by endogenous phospholipase A2, while alkenylacyl- and alkylacylPE were poor substrates for the enzyme. The selective transfer of arachidonic acid into the 2-position of 1-acyl-lysoPE was observed. 1-Alkenyl- and 1-alkyl-lysoPE were also poor substrates for acyl-CoA:lysophospholipid acyltransferase. The acyltransferase activities with the lysoPE analogues were higher than the phospholipase A2 activities with PE analogues. These results suggest that the different incorporation rates of arachidonic acid into alkenylacyl-, alkylacyl- and diacylPE are based on the substrate specificity of endogenous phospholipase A2. 相似文献
49.
Melinda M. Smith Frances W. Robinson Tomoyuki Watanabe Tetsuro Kono 《生物化学与生物物理学报:生物膜》1984,775(2):121-128
The glucose transport activity solubilized from the basal and plus insulin forms of the Golgi-rich fraction of adipocytes was partially characterized, and the results were compared with those of the activity obtained from the plus insulin form of the plasma membrane-rich fraction. The transport activity was determined in a cell-free, reconstituted, system. Prior to reconstitution, the activities in the three preparations were all (a) stable at 0°C for at least 4 h, but not at 37°C or above; (b) most stable at pH 7–9, and (c) less stable in Tes than in Tris buffer. After reconstitution, the three activities were all (d) stable at 0°C, (e) most active at pH 5.5, (f) mildly stimulated by divalent cations, (g) unaffected by insulin or 1 mM of several SH-blocking agents, (h) inhibited by heavy metal ions, 10–100 mM of monovalent salts, organic solvents, several sugar isomers, and specific sugar-transport inhibitors. The rates of d-glucose uptake by the three liposome preparations were all inhibited more strongly by 2-deoxy-d-glucose or than by d-glucose. These data indicate that the general properties of the glucose transport activity in the Golgi-rich fraction are similar to those of the activity in the plasma membrane-rich fraction. 相似文献
50.
Biological activities of chemically synthesized analogues of the nonreducing sugar moiety of lipid A 总被引:12,自引:0,他引:12
M Matsuura Y Kojima J Y Homma Y Kubota A Yamamoto M Kiso A Hasegawa 《FEBS letters》1984,167(2):226-230
Adriamycin-Fe3+ complex catalyzes the formation of hydroxyl radical from hydrogen peroxide but the DNA-adriamycin-iron ternary complex is much more effective. 11-Deoxyadriamycin, which shows no spectral evidence of complex formation with iron, was ineffective. The generation of hydroxyl radical by adriamycin-Fe3+ complex in the presence of DNA correlates with its ability to cleave DNA. Hydroxyl radicals are thus implicated as the reactive oxygen species involved in the DNA damage caused by the adriamycin-Fe3+ complex. 相似文献