全文获取类型
收费全文 | 2359篇 |
免费 | 111篇 |
专业分类
2470篇 |
出版年
2023年 | 6篇 |
2022年 | 25篇 |
2021年 | 45篇 |
2020年 | 17篇 |
2019年 | 29篇 |
2018年 | 48篇 |
2017年 | 31篇 |
2016年 | 54篇 |
2015年 | 97篇 |
2014年 | 101篇 |
2013年 | 115篇 |
2012年 | 184篇 |
2011年 | 188篇 |
2010年 | 124篇 |
2009年 | 93篇 |
2008年 | 158篇 |
2007年 | 166篇 |
2006年 | 149篇 |
2005年 | 121篇 |
2004年 | 184篇 |
2003年 | 147篇 |
2002年 | 111篇 |
2001年 | 27篇 |
2000年 | 14篇 |
1999年 | 26篇 |
1998年 | 18篇 |
1997年 | 14篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1970年 | 5篇 |
1969年 | 2篇 |
1967年 | 3篇 |
排序方式: 共有2470条查询结果,搜索用时 15 毫秒
1.
Shigeki Takeura Hiizu Aoki Tatsuya Tsurumi Yukihiro Nishiyama Hisashi Fujioka Saiji Yoshii Koichiro Maeno 《Microbiology and immunology》1984,28(4):427-437
Host-dependent restriction of influenza B virus replication in L cells was analysed in comparison with productive infection in MDCK or 1–5C-4 cells. The synthesis and intracellular distribution of virus-specific proteins and the production of cytoplasmic ribonucleoproteins in nonpermissive L cells were similar to those in permissive MDCK cells. However, an electron microscopic study of infected L cells showed neither extracellular virions nor budding virus particles on the cell surface, in contrast to MDCK cells which produced numerous virus particles. PAGE analysis of the plasma membrane isolated from the cells demonstrated no significant difference in the composition of viral polypeptides between permissive 1-5C-4 and nonpermissive L cells. It was noted that the abortiveness of influenza B virus infection in L cells may be due to a defect in host cell function involved in the initiation of virus budding. 相似文献
2.
[3H]Dihydroergocryptine ([3H]DHE) was shown to bind to sites in membranes from neuroblastoma X glioma hybrid cells (NG 108-15) that had the characteristics expected of alpha-adrenergic receptors. The binding was saturable with 0.3 pmol [3H]DHE bound per mg of protein and of high affinity, with an apparent dissociation constant (KD) of 1.8 nM. The specificity of the binding site for various ligands was more similar to that of alpha 2 receptors than to that of alpha 1. No specific binding of [3H]WB-4101 was found in the membranes derived from NG 108 cells. This finding also indicated that the [3H]DHE binding site in the cell is the alpha 2 receptor. GTP lowered the affinity of agonists for the [3H]DHE binding site, although the nucleotide hardly affected the affinity of antagonists including [3H]DHE. 相似文献
3.
Tatsuya Matsunami Toshihiro Suzuki Yasuo Hisa Kuniaki Takata Tetsuro Takamatsu Masahito Oyamada 《Cell communication & adhesion》2006,13(1):93-102
To elucidate the role of the spiral limbus in glucose transport in the cochlea, we analyzed the expression and localization of GLUT1, connexin26, connexin30, and occludin in the spiral limbus of the rat cochlea. GLUT1 and occludin were detected in blood vessels. GLUT1, connexin26, connexin30, and occludin were also expressed in fibrocytes just basal to the supralimbal lining cells. Connexin26 and connexin30 were present among not only these GLUT1-positive fibrocytes but also GLUT1-negative fibrocytes. In vivo glucose imaging using 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (6-NBDG, MW 342) together with Evans Blue Albumin (EBA, MW 68,000) showed that 6-NBDG was rapidly distributed throughout the spiral limbus, whereas EBA was localized only in the vessels. Moreover, the gap junctional uncoupler heptanol inhibited the distribution of 6-NBDG. These findings suggest that gap junctions play an important role in glucose transport in the spiral limbus, i.e., that gap junctions mediate glucose transport from GLUT1-positive fibrocytes to GLUT1-negative fibrocytes in the spiral limbus. 相似文献
4.
5.
Compression wood (CW) contains higher quantities of β-1-4-galactan than does normal wood (NW). However, the physiological
roles and ultrastructural distribution of β-1-4-galactan during CW formation are still not well understood. The present work
investigated deposition of β-1-4-galactan in differentiating tracheids of Cryptomeria japonica during CW formation using an immunological probe (LM5) combined with immunomicroscopy. Our immunolabeling studies clearly
showed that differences in the distribution of β-1-4-galactan between NW (and opposite wood, OW) and CW are initiated during
the formation of the S1 layer. At this stage, CW was strongly labeled in the S1 layer, whereas no label was observed in the S1 layer of NW and OW. Immunogold labeling showed that β-1-4-galactan in the S1 layer of CW tracheids significantly decreased during the formation of the S2 layer. Most β-1-4-galactan labeling was present in the outer S2 region in mature CW tracheids, and was absent in the inner S2 layer that contained helical cavities in the cell wall. In addition, delignified CW tracheids showed significantly more labeling
of β-1-4-galactan in the secondary cell wall, suggesting that lignin is likely to mask β-1-4-galactan epitopes. The study
clearly showed that β-1-4-galactan in CW was mainly deposited in the outer portion of the secondary cell wall, indicating
that its distribution may be spatially consistent with lignin distribution in CW tracheids of Cryptomeria japonica. 相似文献
6.
Madhusoodana P. Nambiar Tatsuya Oda Chaohua Chen Yasuo Kuwazuru Henry C. Wu 《Journal of cellular physiology》1993,154(2):222-228
The intracellular pathway following receptor-mediated endocytosis of cholera toxin was studied using brefeldin A (BFA), which inhibited protein secretion and induced dramatic morphological changes in the Golgi region. In both mouse Y1 adrenal cells and CHO cells, BFA at 1 μg/ml caused a 80–90% inhibition of the cholera toxin (CT)-elevation of intracellular cAMP. The inhibition of the cytotoxicity of CT by BFA was also observed in a rounding assay of Y1 adrenal cells. The inhibition of CT cytotoxicity by BFA was dose dependent, with the ID50 value similar to the LD50 of BFA in Y1 adrenal cells. Binding and internalization of [125I]-cholera toxin in Y1 adrenal cells was not affected by BFA. Unlike the BFA-sensitive cell lines such as Y1 adrenal and CHO cells, BFA at 1 μg/ml did not inhibit the cytotoxicity of CT in PtK1 cells, of which the Golgi structure was BFA-resistant. These results strongly suggest that a BFA-sensitive Golgi is required for the protection of CT cytotoxicity by BFA. In contrast, elevation of the intracellular cAMP by forskolin, which acts directly on the plasma membrane adenylate cyclase, was not affected by BFA. These observations indicate that the intoxication of target cells by CT requires an intact Golgi region for its intracellular trafficking and/or processing. In this respect, CT shares a common intracellular pathway with ricin, Pseudomonas toxin, and modeccin, even though their structures and modes of action are very different. © 1993 Wiley-Liss, Inc. 相似文献
7.
Simulation study on effects of channel noise on differential conduction at an axon branch. 总被引:1,自引:0,他引:1 下载免费PDF全文
Y Horikawa 《Biophysical journal》1993,65(2):680-686
Effects of membrane channel noise (random opening and closing of ion channels) are studied on spike conduction at a branching point on an axon. Computer simulation is done on the basis of a stochastic version of the Hodgkin-Huxley cable model, into which the channel noise is incorporated. It is shown that the channel noise makes conduction of spikes into daughter branches random; spikes randomly succeed or fail in conduction into daughter branches. The conduction is then randomly differential even though the forms and properties of daughter branches are the same. The randomness is considerable when the radius of an axon is small (approximately 1 microns). 相似文献
8.
Fast blue (FB), rhodamine microspheres (RH), horseradish peroxidase (HRP), and wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) were used as retrograde tracers to study the innervation of the rat superficial pineal gland (SP). One of the tracers was injected into the gland of each animal. All four retrograde tracers injected into the gland always labeled neurons in the superior cervical ganglia (SCG). No retrograde labeling was ever seen in the suprachiasmatic nuclei, paraventricular hypothalamic nuclei, lateral hypothalamus, habenular nuclei, amygdalar nuclei, or superior salivatory nuclei. Retrograde labeling was seen in the anterior hypothalamic nuclei, anterior thalamic nuclei, lateral geniculate bodies, and midbrain tectal structures when a tracer spread from the injection site to the overlying cortex, tectum, or commissures. Control studies included injection of tracer into the subarachnoid space around the SP or into structures adjacent to the SP. Only the injection of FB or WGA-HRP into the subarachnoid space labeled neurons in the SCG. This labeling was probably due to the spread of tracer to the choroid plexus. These results agree with recent work confirming the existence of a direct projection of the SCG into the interstitium around pinealocytes. The evidence does not substantiate an innervation originating in the habenular nuclei; the superior salivatory nuclei; or any other diencephalic, midbrain, pontine, or medullary structure. 相似文献
9.
10.
Haruaki Uchiyama Koichi Ohara Kazuko Haga Tatsuya Haga Arata Ichiyama 《Journal of neurochemistry》1990,54(6):1870-1881
Muscarinic acetylcholine receptors purified from porcine cerebra or atria were covalently labeled with [3H]propylbenzilylcholine mustard ([3H]PrBCM), and then the labeled receptors were subjected to limited hydrolysis with trypsin, V8 protease, and lysyl endopeptidase, followed by analysis involving sodium dodecyl sulfate-polyacrylamide gel electrophoresis, fluorography, autoradiography, or immunostaining. The labeled peptides were located on the basis of their reactivity with antibodies raised against three synthetic peptides with partial sequences of the m1 or m2 receptor, and of their sensitivity to endoglycosidase F, which was taken as evidence that they contain glycosylation sites near the N terminus. The [3H]PrBCM-binding site in both cerebral and atrial receptors was found to be located between the N terminus and the second intracellular loop, because the size of the smallest deglycosylated peptide that contained both the [3H]PrBCM-binding and glycosylation sites was approximately 16 kDa. Cerebral receptors were 32P-phosphorylated with protein kinase C, and the major phosphorylation sites in cerebral muscarinic receptors were found to be located in a C-terminal segment including a part of the third intracellular loop, because a 32P-labeled peptide of 12-14 kDa reacted with anti-(m1 C-terminal peptide) antiserum. The presence of an intramolecular disulfide bond, probably between Cys 98 and Cys 178 in the first and second extracellular loops, respectively, was suggested by the finding that a peptide of approximately 17 kDa containing the [3H]PrBCM-binding site, but not the glycosylation sites, was partly converted to a peptide of approximately 12 kDa on treatment with beta-mercaptoethanol. 相似文献