首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   856篇
  免费   38篇
  国内免费   19篇
  2023年   6篇
  2022年   7篇
  2021年   16篇
  2020年   22篇
  2019年   18篇
  2018年   33篇
  2017年   20篇
  2016年   26篇
  2015年   20篇
  2014年   48篇
  2013年   87篇
  2012年   41篇
  2011年   33篇
  2010年   45篇
  2009年   45篇
  2008年   45篇
  2007年   46篇
  2006年   37篇
  2005年   19篇
  2004年   22篇
  2003年   19篇
  2002年   14篇
  2001年   14篇
  2000年   14篇
  1999年   12篇
  1998年   12篇
  1997年   13篇
  1996年   7篇
  1995年   12篇
  1994年   12篇
  1993年   10篇
  1992年   7篇
  1991年   5篇
  1990年   7篇
  1989年   3篇
  1988年   9篇
  1987年   3篇
  1986年   4篇
  1985年   8篇
  1984年   14篇
  1983年   13篇
  1982年   13篇
  1981年   10篇
  1980年   5篇
  1979年   5篇
  1978年   11篇
  1977年   5篇
  1976年   4篇
  1975年   5篇
  1974年   5篇
排序方式: 共有913条查询结果,搜索用时 15 毫秒
1.
The presence of rhodopsin-like protein was detected in the head of the freshwater planarian Dugesia japonica japonica Ichikawa et Kawakatsu by use of anti-frog-rhodopsin rabbit IgG. Two membrane proteins of molecular weights 65000 and 62000 were separated by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis and found to react with the anti-rhodopsin IgG. The antibody may be useful for monitoring regeneration of the planarian eye.  相似文献   
2.
Abstract Significantly higher Giardia lamblia trophozoites load in the intestine of infected mice accompanied pronounced influx of suppressor/cytotoxic T cells (Lyt 2.2+), T cells (Thy 1.2+) and significant reduction in IgA-containing cells in the gut during the establishment and peak phases of infection. The induction of helper/inducer T cells (Lyt 1.1+) and significant enhancement of IgA-containing cells in gut resulted in the decline of the trophozoite loads. However, the prior treatment of animals with dexamethasone alone resulted in significant reduction in helper/inducer T cells (Lyt 1.1+) and the IgA-containing cells in the gut; the percents of suppressor/cytotoxic T cells (Lyt 2.2+) and IgM-containing cells remained unaltered. Although the G. lamblia infection in such animals further significantly increased the influx of suppressor/cytotoxic T cells, the late response of helper/inducer T cells and IgA-containing cells was abrogated during the decline phase of infection. The significant reduction in the trophozoite load — despite immuno-suppressive therapy — appeared to be due to unaltered IgM response in such animals which probably took over the function of IgA in defense against G. lamblia . The data of the investigation thus suggested a role of helper/inducer T cells and antibodies producing cells in gut as important effector cells resulting in the termination of primary G. lamblia infection.  相似文献   
3.
BackgroundPrevious reports have shown that pulmonary and systemic hypergamma-globulinemia in CF patients is a reflection of chronic pulmonary infection. Infection with Pseudomonas aeruginosa is known to have major prognostic significance in patients CF. This study aims to identify the incidence of immunoglobulins (especially: IgG, and IgE) in a cohort of CF patients.MethodsA total of 297 patients recruited all over the country’s region for this study were a as part of the CF registry data from 1st January 1984 to 1st June 2016. All patients had their immunoglobulin levels measured by enzyme link immunosorbent assay (ELISA) in 3 stages, at presentation and two follow-ups.ResultsOf the 297 patients recruited, 139 (46.8%) were males while 158 (53.2%) were females. IgA and IgM levels were found not to have risen above the previously reported levels in healthy individuals in all stages. On the contrary, IgE level increased from 209.51 ± 32.30 KU/L to 303.58 ± 37.11 KU/L from baseline to stage 3 while IgG level rose from 12.26 ± 0.43 mg/mL to 17.17 ± 1.68 mg/mL for baseline and stage 3 respectively all above previously reported levels in healthy individuals.ConclusionThis study establishes a potential for the use of IgE and IgG in disease diagnosis as well as the prognostic implications. However, further study is needed to identify the role of infection or medications in relation to the rise of both IgE and IgG with advancement of age and progression of disease severity which may inherently confound the observed results.  相似文献   
4.
Melittin peptides carrying 2,4-dinitro-6-carboxyphenyl (Dncp) haptenic groups regularly evoked anti-hapten IgG responses in mice or guinea pigs when the hapten was C-terminally attached. Single haptens on the N-terminal helix in several positions gave poor or no responses in the early stages but adequate titres after prolonged immunization. Peptides with Dncp at the C-terminus as an invariant feature and a second Dncp in various positions along the peptide chain did not fail to produce adequate responses. The hampering effect is not due to a defect at the T-cell level but involves the recognition step on the B-cell. It is implied that the haptenic interaction with the paratope of the recognizing immunoglob ulin on the B-cell involves the cell membrane in an important way. It is also suggested that late antibody responses should not be overlooked during the development of proteinaceous immunogens for vaccination.  相似文献   
5.
《Cell reports》2020,30(2):351-366.e7
  1. Download : Download high-res image (294KB)
  2. Download : Download full-size image
  相似文献   
6.
7.
The translational diffusion coefficient D 20,w 0 , of monomeric human immunoglobulin G (IgG) has been studied by photon-correlation spectroscopy as a function of pH and protein concentration. At pH 7.6, we find D 20,w 0 =3.89×10–7±0.02 cm2/sec, in good agreement with the value determined by classic mehods. This value corresponds to an effective hydrodynamic radius R, of 55.1±0.3 Å. As pH is increased to 8.9; with the same ionic strength, the molecule appears to expand slightly (3.5% increase in hydrodynamic radius). The concentration dependence of the IgG diffusion constant is interpreted in terms of solution electrostatic effects and shows that long-range repulsive interactions are negligible in the buffer used. The diffusion coefficient for dimeric IgG has also been determined to be D20,w=2.81×10–7±0.04 cm2/sec at 1.6 mg/ml, which corresponds to a hydrodynamic radius of 75 Å. For light-scattering studies of protein molecules in the dimension range of 5–10 nm (Mr=105–107) we find monomeric horse spleen ferritin well suited as a reference standard. Ferritin is a spherical molecule with a hydrodynamic radius R of 6.9±0.1 nm and is stable for years in our standard Tris-HCl-NaCl buffer even at room temperature.  相似文献   
8.
依据GenBank中SARS基因组序列,采用人工合成的方法合成编码SARS病毒N蛋白的全基因(1296bp)序 列,再与设计的CTL特异性表位基因(195bp)重组后,克隆到pET-28a( )质粒中,重组质粒转化到大肠杆菌BL21 (DE3)中诱导表达。利用SARS患者恢复期阳性血清,鉴定表达蛋白。进一步纯化后免疫马,并用ELISA方法检 测血清抗体效价。结果显示SDS-PAGE表明所表达的蛋白相对分子质量约为55000 Da,与预计大小相符;Western blot显示表达的蛋白具有良好的抗原性和特异性。对表达蛋白形成的包涵体进行洗涤,得到的蛋白纯度可达到 70.1%。切胶纯化免疫马后,获得的抗SARS抗体滴度达1:2560。为亚单位疫苗研制和精制抗SARS抗体免疫制 剂提供基础。  相似文献   
9.
发展了一种在实验室大幅度提高抗体产量的方法,即采用添加2%的去免疫球蛋白IgG的腹水于无血清培养基中的方法,培养杂交瘤细胞,获得了高达3.55 ×106/ml的细胞密度,纯化后获得了135μg/ml的单克隆抗体产量,比通常的用无血清培养的单位体积培养液抗体产量高4倍。对于体外生产单克隆抗体而言,这种方法经济并且易于推广,它的成功是抗体产量提高的一个巨大进步。  相似文献   
10.
Structural changes in different parts of the brain in rheumatoid arthritis (RA) patients have been reported. RA is not regarded as a brain disease. Body organs such as spleen and lung produce RA-relevant genes. We hypothesized that the structural changes in the brain are caused by changes of gene expression in body organs. Changes in different parts of the brain may be affected by altered gene expressions in different body organs. This study explored whether an association between gene expressions of an organ or a body part varies in different brain structures. By examining the association of the 10 most altered genes from a mouse model of spontaneous arthritis in a normal mouse population, we found two groups of gene expression patterns between five brain structures and spleen. The correlation patterns between the prefrontal cortex, nucleus accumbens, and spleen were similar, while the associations between the other three parts of the brain and spleen showed a different pattern. Among overall patterns of the associations between body organs and brain structures, spleen and lung had a similar pattern, and patterns for kidney and liver were similar. Analysis of the five additional known arthritis-relevant genes produced similar results. Analysis of 10 nonrelevant-arthritis genes did not result in a strong association of gene expression or clearly segregated patterns. Our data suggest that abnormal gene expressions in different diseased body organs may influence structural changes in different brain parts.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号