全文获取类型
收费全文 | 1243篇 |
免费 | 113篇 |
出版年
2021年 | 9篇 |
2018年 | 9篇 |
2017年 | 16篇 |
2016年 | 17篇 |
2015年 | 19篇 |
2014年 | 28篇 |
2013年 | 45篇 |
2012年 | 70篇 |
2011年 | 58篇 |
2010年 | 35篇 |
2009年 | 36篇 |
2008年 | 38篇 |
2007年 | 44篇 |
2006年 | 42篇 |
2005年 | 48篇 |
2004年 | 60篇 |
2003年 | 48篇 |
2002年 | 61篇 |
2001年 | 43篇 |
2000年 | 70篇 |
1999年 | 49篇 |
1998年 | 19篇 |
1997年 | 19篇 |
1996年 | 18篇 |
1995年 | 26篇 |
1994年 | 22篇 |
1993年 | 14篇 |
1992年 | 42篇 |
1991年 | 28篇 |
1990年 | 27篇 |
1989年 | 43篇 |
1988年 | 33篇 |
1987年 | 29篇 |
1986年 | 27篇 |
1985年 | 19篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 19篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1974年 | 8篇 |
1972年 | 6篇 |
1971年 | 5篇 |
1970年 | 7篇 |
1969年 | 6篇 |
1968年 | 6篇 |
排序方式: 共有1356条查询结果,搜索用时 343 毫秒
31.
M Kita Y Ohmoto Y Hirai N Yamaguchi J Imanishi 《Comptes rendus des séances de la Société de biologie et de ses filiales》1990,184(5-6):380-384
Mycoplasma shows a variety of effects on immune system, including the activation of macrophage, the increase in T cell cytotoxicity, and the enhancement of the proliferation and maturation of B cells, etc. As it is well known that many cytokines regulate the immune system, it is interesting to examine whether or not human peripheral blood mononuclear cells (PBMC) produce interleukin (IL) in response to mycoplasmas. In the present study, human PMBC were incubated with 7 species of mycoplasmas for 48 hours, and IL-1 beta, IL-2 and IL-6 activities in the supernatants were determined by ELISA. All the species of mycoplasmas were able to induce IL-1 beta and IL-6, although IL-2 was induced only by M. pneumoniae. These results suggest that the influence of mycoplasma infection on immune system may be partly due to the interleukins induced by mycoplasmas. 相似文献
32.
33.
Introduction of p130cas signaling complex formation upon integrin-mediated cell adhesion: a role for Src family kinases. 总被引:14,自引:5,他引:9 下载免费PDF全文
Integrin-mediated cell adhesion triggers intracellular signaling cascades, including tyrosine phosphorylation of intracellular proteins. Among these are the focal adhesion proteins p130cas (Cas) and focal adhesion kinase (FAK). Here we identify the kinase(s) mediating integrin-induced Cas phosphorylation and characterize protein-protein interactions mediated by phosphorylated Cas. We found that expression of a constitutively active FAK in fibroblasts results in a consecutive tyrosine phosphorylation of Cas. This effect required the autophosphorylation site of FAK, which is a binding site for Src family kinases. Integrin-mediated phosphorylation of Cas was not, however, compromised in fibroblasts lacking FAK. In contrast, adhesion-induced tyrosine phosphorylation of Cas was reduced in cells lacking Src, whereas enhanced phosphorylation of Cas was observed Csk- cells, in which Src kinases are activated. These results suggest that Src kinases are responsible for the integrin-mediated tyrosine phosphorylation of Cas. FAK seems not to be necessary for phosphorylation of Cas, but when autophosphorylated, FAK may recruit Src family kinases to phosphorylate Cas. Cas was found to form complexes with Src homology 2 (SH2) domain-containing signaling molecules, such as the SH2/SH3 adapter protein Crk, following integrin-induced tyrosine phosphorylation. Guanine nucleotide exchange factors C3G and Sos were found in the Cas-Crk complex upon integrin ligand binding. These observations suggest that Cas serves as a docking protein and may transduce signals to downstream signaling pathways following integrin-mediated cell adhesion. 相似文献
34.
Takeshi K. Watanabe Toyomasa Katagiri Mikio Suzuki Fumio Shimizu Tsutomu Fujiwara Naohide Kanemoto Yusuke Nakamura Yoshikatsu Hirai Hiroumi Maekawa Ei-ichi Takahashi 《Genomics》1996,38(3):273
From a human fetal-brain cDNA library we isolated two novel genes encoding peptides containing six EGF-like repeats. Both showed significant homologies with nel, a gene strongly expressed in neural tissues of chicken. The cDNAs, designated NELL1 (nel-like, type 1) and NELL2 (nel-like, type 2), contained open reading frames encoding 810 and 816 amino acids, respectively. NELL2 is strongly expressed in brain of adult and fetus but only weakly in fetal kidney. NELL1 and NELL2 were mapped by FISH to chromosomal bands 11p15.1–p15.2 and 12q13.11–q13.12, respectively. 相似文献
35.
36.
Jianyu Zheng Kohei Irifune Kouji Hirai Masashi Nakata Ryuso Tanaka Hiromichi Morikawa 《Journal of plant research》1994,107(4):365-369
In situ hybridization with a biotin-labeled rice ribosomal DNA (rDNA) probe to the somatic metaphase chromosomes of six species ofPhaseolus andVigna (P. angularis, P. calcaratus, P. coccineus, P. vulgaris, V. sesquipedalis andV. sinensis) was done to determine the sites of rDNA. Hybridization signals were present in the terminal and subterminal chromosome regions
of each of the six species. The number of rDNA sites was two inP. angularis andP. calcaratus, four inP. coccineus andP. vulgaris, and six inV. sesquipedalis andV. sinensis. 相似文献
37.
Hirai Nobuhiro; Kojima Yasuhiro; Koshimizu Koichi; Shinozaki Masateru; Takimoto Atsushi 《Plant & cell physiology》1993,34(7):1039-1044
Flowering of Pharbitis nil strain Violet is induced in continuouslight under poor nutritional conditions. High-performance liquidchromatography of extracts of the cotyledons revealed that twocompounds in addition to chlorogenic acid accumulate under suchconditions. The compounds were identified as pinoresinol glucosideand p-coumaroylquinic acid. The endogenous levels of these phenylpropanoidswere correlated with the flowering response when nutrition waspoor. However, activation of phenylpropanoid biosynthesis seemednot to be essential for the induction of flowering. (Received May 17, 1993; Accepted July 26, 1993) 相似文献
38.
Kazuyoshi Masuda Shunji Nagata Koichiro Hirano Yasushi Takagishi Hidematsu Hirai 《Microbiology and immunology》1993,37(2):165-167
This paper describes an attempt to effectively induce antibody-dependent cell-mediated cytotoxicity (ADCC) in nude mice. A monoclonal antibody against α-fetoprotein, 80G, coadministered with spleen cells from other nude mice bearing HuH-7N (xenograft of human hepatoma cell line, HuH-7) significantly suppressed the growth of HuH-7N as compared to treatment with 80G alone. 80G with spleen cells from normal nude mice also had some suppressive effect. In contrast, no effect was observed with each spleen cells alone as well as 80G alone. These results suggest that further supply of effector cells could enhance ADCC activity in nude mice. 相似文献
39.
Kazuyoshi Masuda Shunji Nagata Koichiro Hirano Yasushi Takagishi Hidematsu Hirai 《生物化学与生物物理学报:疾病的分子基础》1993,1182(2):128-132
This study was carried out to clarify the reason for elevation of serum α-fetoprotein (AFP) level of nude mice bearing hepatoma cells after treatment with monoclonal antibodies (MoAbs) to AFP. MoAbs to AFP showed no effect on the cumulative amounts of AFP secreted from human hepatoma cell line, HuH-7, in vitro. However, the treatment of nude mice bearing HuH-7N cells (HuH-7 xenograft) with MoAbs to AFP led to elevation of the serum AFP level in spite of the fact that the growth curve of HuH-7N cells was similar to that for PBS treatment. This apparent elevation of the serum AFP level is thought to be due to the slow elimination of AFP-MoAb immune complexes with little lattice structure from circulation, but not the enhancement of AFP secretion of HuH-7N cells. Thus, when using a MoAb alone or MoAb-drug conjugate, the serum AFP level should only be cautiously used as a tumor marker for evaluating the targeting immunotherapy. 相似文献
40.
Transforming growth factor beta (TGF beta) regulates the growth of human umbilical vein endothelial cells (HUVEC) differently depending on the isoform of TGF beta and the culture conditions. The cells are resistant to growth inhibition by TGF beta when the cells are cultured on substratum coated with gelatin. However, the proliferation of HUVEC cultured on substratum without a gelatin coating is inhibited by TGF beta, depending on the isoform and concentration of TGF beta. Binding assays with 125I-TGF beta 1 reveal that HUVEC contain a single class of high-affinity (Kd = 4.4 pM) TGF beta 1 binding sites with 8500 sites per cell. Affinity cross-linking studies demonstrate that HUVEC express 180 and 80 kDa TGF beta 1 binding sites that do not bind TGF beta 2. The reduction and the removal of glycosaminoglycans does not affect the electrophoretic mobility of the 180-kDa binding protein cross-linked with 125I-TGF beta 1. Therefore, the 180-kDa TGF beta 1 binding protein is not related to the type III TGF beta receptor, but might be a novel TGF beta 1-specific receptor/binding protein expressed on vascular endothelial cells. The expression of TGF beta 1 binding sites is not affected by the presence or absence of the gelatin coating on the culture substratum. The data suggest that a gelatin coating does not regulate the susceptibility of HUVEC to TGF beta 1 at the level of the receptor/binding proteins, and that growth inhibition of HUVEC by TGF beta 1 is linked to the regulation of extracellular matrices required for the interaction between the cells and the substratum. 相似文献