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   410篇
  免费   36篇
  446篇
  2022年   4篇
  2021年   5篇
  2020年   8篇
  2019年   2篇
  2018年   7篇
  2017年   2篇
  2016年   9篇
  2015年   20篇
  2014年   10篇
  2013年   16篇
  2012年   24篇
  2011年   21篇
  2010年   14篇
  2009年   16篇
  2008年   22篇
  2007年   15篇
  2006年   18篇
  2005年   18篇
  2004年   23篇
  2003年   29篇
  2002年   15篇
  2001年   16篇
  2000年   18篇
  1999年   12篇
  1998年   8篇
  1997年   9篇
  1996年   9篇
  1994年   4篇
  1993年   6篇
  1992年   6篇
  1991年   3篇
  1990年   3篇
  1989年   9篇
  1988年   6篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1980年   2篇
  1976年   1篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1971年   2篇
  1969年   1篇
  1968年   1篇
  1960年   1篇
排序方式: 共有446条查询结果,搜索用时 10 毫秒
111.
There was a significant amount of non‐specific, but not of allergen (e.g., papain, mite feces and four kinds of pollen)‐specific, IgE antibodies (Abs) in the sera of normal mice. An i.n. injection of each allergen without adjuvant into mice caused an increase in total IgE Ab titers with a similar time course in the serum. However, the stage of initiation of allergy varied from allergen to allergen. Submandibular lymph node cells from normal mice contained papain‐, but not mite feces‐ or pollen‐specific IgE+ cells and an i.n. injection of papain induced papain‐specific IgE Abs in the serum. In contrast, one (i.n.) or two (i.n. and s.c) injections of mite feces induced neither mite feces‐specific IgE+ cells in the lymph nodes nor mite feces‐specific IgE Abs in the serum. I.n. sensitization with cedar pollen induced cedar pollen‐specific IgE+ small B cells in the lymph nodes on Day 10, when non‐specific IgE Ab titers reached a peak in the serum, implying induction of related allergen‐specific IgE+ small cells as well. In fact, a second (s.c.) injection of ragweed (or cedar) pollen into mice sensitized i.n. once with cedar (or ragweed) pollen, but not with mite feces, induced a large amount of ragweed (or cedar) pollen‐specific IgE Abs in the serum. These results indicate that when firstly‐sensitized non‐specific IgE+ small B cells in mouse lymph nodes include some secondly‐sensitized allergen‐specific ones, mice produce IgE Abs specific for the secondly‐injected allergen.
  相似文献   
112.
Advanced glycation end products (AGEs) formed from glyceraldehyde (Gcer) and glycolaldehyde (Gcol) are involved in the pathogenesis of diabetic complications, via interactions with a receptor for AGEs (RAGE). In this study, we aimed to elucidate the RAGE-binding structure in Gcer and Gcol-derived AGEs and identify the minimal moiety recognized by RAGE. Among Gcer and Gcol-derived AGEs, GLAP (glyceraldehyde-derived pyridinium) and GA-pyridine elicited toxicity in PC12 neuronal cells. The toxic effects of GLAP and GA-pyridine were suppressed in the presence of anti-RAGE antibody or the soluble form of RAGE protein. Furthermore, the cytotoxicity test using GLAP analog compounds indicated that the 3-hydroxypyridinium (3-HP) structure is sufficient for RAGE-dependent toxicity. Surface plasmon resonance analysis showed that 3-HP derivatives directly interact with RAGE. These results indicate that GLAP and GA-pyridine are RAGE-binding epitopes, and that 3-HP, a common moiety of GLAP and GA-pyridine, is essential for the interaction with RAGE.  相似文献   
113.
Human natural killer cells and a subset of T cells express a repertoire of killer cell immunoglobulin receptors (KIRs) that recognize major histocompatibility complex (MHC) class I molecules. KIRs and T cell receptors (TCRs) bind in a peptide-dependent manner to overlapping regions of peptide-MHC class I complexes. KIRs with two immunoglobulin domains (KIR2Ds) recognize distinct subsets of HLA-C alleles. Here we use surface plasmon resonance to study the binding of soluble forms of KIR2DL1 and KIR2DL3 to several peptide-HLA-Cw7 complexes. KIR2DL3 bound to the HLA-Cw7 allele presenting the peptide RYRPGTVAL with a 1:1 stoichiometry and an affinity (K(d) approximately 7 microM at 25 degrees C) within the range of values measured for other cell-cell recognition molecules, including the TCR. Although KIR2DL1 is reported not to recognize the HLA-Cw7 allele in functional assays, it bound RYRPGTVAL/HLA-Cw7, albeit with a 10-20-fold lower affinity. TCR/peptide-MHC interactions are characterized by comparatively slow kinetics and unfavorable entropic changes (Willcox, B. E., Gao, G. F., Wyer, J. R. , Ladbury, J. E., Bell, J. I., Jakobsen, B. K., and van der Merwe, P. A. (1999) Immunity 10, 357-365), suggesting that binding is accompanied by conformational adjustments. In contrast, we show that KIR2DL3 binds RYRPGTVAL/HLA-Cw7 with fast kinetics and a favorable binding entropy, consistent with rigid body association. These results indicate that KIR/peptide-MHC class I interactions have properties typical of other cell-cell recognition molecules, and they highlight the unusual nature of TCR/peptide-MHC recognition.  相似文献   
114.
High activity of angiotensin-converting enzyme was demonstrated in human pituitary tissue. This activity required the presence of chloride ion and was almost completely inhibited by a specific converting enzyme inhibitor captopril (10 nM), indicating that the activity measured is indeed angiotensin-converting enzyme. The specific activity of the enzyme was 1.68 +/- 1.20 nmol hippuric acid generated mg of protein-1 min-1 (mean +/- SD, for 11 specimens). The biochemical features of the enzyme were closely related to the well-characterized human lung converting enzyme, such as molecular weight (290,000), optimum pH (8.0-8.5), the presence of glycoprotein residues, and dependence on chloride ion concentration. These results provide definitive evidence for the presence of angiotensin-converting enzyme in human pituitary tissue.  相似文献   
115.
To gain insight into the genetic mechanisms of photoreceptor development, we analyzed a collection of zebrafish mutations characterized by early photoreceptor cell loss. The mutant defects impair outer segment formation and are accompanied by an abnormal distribution of visual pigments. Rods and different cone types display defects of similar severity suggesting that genetic pathways common to all photoreceptors are affected. To investigate whether these phenotypes involve cell–cell interaction defects, we analyzed genetically mosaic animals. Interaction of niezerka photoreceptors with wild-type tissues improves the survival of mutant cells and restores their elongated morphology. In contrast, cells carrying mutations in the loci brudas, elipsa, fleer, and oval retain their defective phenotypes in a wild-type environment indicating cell-autonomy. These experiments identify distinct phenotypic categories of photoreceptor mutants and indicate that zebrafish photoreceptor defects involve both cell-autonomous and cell-nonautonomous mechanisms.  相似文献   
116.
Magnolia stellata is a rare subcanopy tree species that grows in secondary forests in warm temperate zones. It is now endangered due to habitat degradation by vegetation succession. In an attempt to improve the habitat, a 30 m?×?10 m plot (0.03 ha) was set up with all vegetation including M. stellata being clear-cut in January 2012. The number of sprouts increased for 1–2 years after clear-cutting and then gradually decreased or remained constant. Five years after clear-cutting, the numbers of individuals and stems, and the total basal area (BA), were 87.0, 165.5 and 3.2%, respectively, of the values before clear-cutting. BA was highest for Ilex pedunculosa, followed by M. stellata and Hydrangea paniculata. Some sprouted individuals of M. stellata produced flower buds in the second year after clear-cutting, and flowered and fruited in the spring and summer of the third year, respectively. The densities of potential canopy species were 18,533 ha?1 (height >?0.5 m) and 7,267 ha?1 (height >?1.2 m), vastly exceeding the value of the criterion for successful natural regeneration after clear-cutting of warm temperate forests in the region (3,000 ha?1). Based on this criterion, it is thus considered that the natural regeneration has reached completion. However, 45.1% (height >?0.5 m) and 95.5% (height >?1.2 m) of M. stellata individuals were regenerated by sprouting. Further research is needed into how individuals, regenerated from seedlings, develop and reach sexual maturity, and how successive generations change.  相似文献   
117.
Fucosylated haptoglobin (Fuc-Hpt) and Mac-2 binding protein (Mac-2 bp) are identified as cancer biomarkers, based on the results from a glyco-proteomic analysis. Recently, we reported that these glyco-biomarkers were associated with liver fibrosis and/or ballooning hepatocytes in patients with nonalcoholic fatty liver disease (NAFLD). We evaluated the ability of these glycoproteins to estimate liver fibrosis in 317 patients with chronic hepatitis C. We measured the serum Fuc-Hpt and Mac-2 bp levels using a lectin-antibody ELISA and ELISA, respectively. The serum levels of both Fuc-Hpt and Mac-2 bp increased with the progression of liver fibrosis. The multivariate analysis revealed that Mac-2 bp was an independent factor associated with moderate liver fibrosis (F ≥ 2). In contrast, Fuc-Hpt was an independent factor associated with advanced liver fibrosis (F ≥ 3). In terms of evaluating liver fibrosis, the serum levels of these glycomarkers were correlated with well-known liver fibrosis indexes, such as the aspartate aminotransferase to platelet ratio index (APRI) and Fibrosis-4 (FIB4) index. An assay that combined the APRI or FIB4 index and the Fuc-Hpt or Mac-2 bp levels increased the AUC value for diagnosing hepatic fibrosis. Interestingly, the cumulative incidence of hepatocellular carcinoma (HCC) was significantly higher in the patients with elevated serum levels of Fuc-Hpt and Mac-2 bp. In conclusion, both Fuc-Hpt and Mac-2 bp could be useful glyco-biomarkers of liver fibrosis and predictors of HCC in patients with chronic hepatitis C.  相似文献   
118.
119.
Vital statistics on the breeding through successive generations were presented for the cynomolgus monkey colony of NIH, Tokyo. The results of this retrospective survey clearly demonstrated the third (F2) and the fourth (F3) generations could be bred and reared successfully by the indoor caged-breeding system in which either individual timed-mating or group mating procedure was adopted. Several important and difficult problems involved in the production of successive generations of the cynomolgus monkey by our breeding system were discussed from the standpoint of laboratory animal science.  相似文献   
120.
Summary We describe a genetic polymorphism of human lymphocyte cytosol major polypeptide with mol. wt. 64,000, detected in peripheral blood lymphocytes by high resolution two-dimensional electrophoresis. Three different electrophoretic types (1-1, 2-1, 2-2) of the polypeptide have been identified. Family and population studies indicate that the three phenotypes of the polypeptide are determined by two common alleles at a single autosomal locus. The polypeptide occurs in the cytosol and is predominent in peripheral blood lymphocytes, B-lymphoblastoid cells, T-lymphoblastoid cells, lymph node, and spleen. The polypeptide has not been detected in HeLa cells, fibroblasts, erythrocytes, serum, and cerebrum. Traces of the polypeptide exist in liver, kidney, and skeletal muscle. It is proposed that the polypeptide and its locus be temporarily designated lymphocyte cytosol 64K polypeptide (LC64K polypeptide) andLC64P, respectively. In a Japanese population, the gene frequencies ofLC64P 1 andLC64P 2 were 0.936 and 0.064, respectively. The data suggest thatLC64P is a new locus, product of which shows genetic polymorphism and is associated with the function and/or the structure of lymphocytes.  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