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   1251篇
  免费   97篇
  国内免费   4篇
耳鼻咽喉   8篇
儿科学   26篇
妇产科学   17篇
基础医学   159篇
口腔科学   41篇
临床医学   106篇
内科学   325篇
皮肤病学   58篇
神经病学   106篇
特种医学   16篇
外科学   147篇
综合类   3篇
预防医学   63篇
眼科学   54篇
药学   105篇
中国医学   9篇
肿瘤学   109篇
  2024年   2篇
  2023年   19篇
  2022年   43篇
  2021年   77篇
  2020年   33篇
  2019年   37篇
  2018年   47篇
  2017年   39篇
  2016年   47篇
  2015年   44篇
  2014年   55篇
  2013年   52篇
  2012年   77篇
  2011年   80篇
  2010年   47篇
  2009年   41篇
  2008年   79篇
  2007年   72篇
  2006年   67篇
  2005年   56篇
  2004年   54篇
  2003年   76篇
  2002年   79篇
  2001年   17篇
  2000年   13篇
  1999年   11篇
  1998年   2篇
  1997年   4篇
  1996年   10篇
  1995年   3篇
  1994年   5篇
  1993年   2篇
  1992年   10篇
  1991年   2篇
  1990年   4篇
  1989年   6篇
  1988年   6篇
  1987年   4篇
  1986年   5篇
  1985年   2篇
  1984年   1篇
  1983年   2篇
  1979年   11篇
  1978年   1篇
  1977年   1篇
  1975年   3篇
  1969年   3篇
  1967年   1篇
排序方式: 共有1352条查询结果,搜索用时 15 毫秒
51.
IL‐22 induces STAT3 phosphorylation and mediates psoriasis‐related gene expression. However, the signaling mechanism leading from pSTAT3 to the expression of these genes remains unclear. We focused on Bcl‐3, which is induced by STAT3 activation and mediates gene expression. In cultured human epidermal keratinocytes, IL‐22 increased Bcl‐3, which was translocated to the nucleus with p50 via STAT3 activation. The increases in CXCL8, S100As and human β‐defensin 2 mRNA expression caused by IL‐22 were abolished by siRNA against Bcl‐3. Although CCL20 expression was also augmented by IL‐22, the knockdown of Bcl‐3 increased its level. Moreover, the combination of IL‐22 and IL‐17A enhanced Bcl‐3 production, IL‐22‐induced gene expression, and the expression of other psoriasis‐related genes, including those encoding IL‐17C, IL‐19, and IL‐36γ. The expression of these genes (except for CCL20) was also suppressed by the knockdown of Bcl‐3. Bcl‐3 overexpression induced CXCL8 and HBD2 expression but not S100As expression. We also compared Bcl‐3 expression between psoriatic skin lesions and normal skin. Immunostaining revealed strong signals for Bcl‐3 and p50 in the nucleus of epidermal keratinocytes from psoriatic skin. The IL‐22‐STAT3‐Bcl‐3 pathway may be important in the pathogenesis of psoriasis.  相似文献   
52.
Carbon monoxide (CO) has potent anti-inflammatory and anti-oxidant effects. We report herein on the preparation of a nanotechnology-based CO donor, CO-bound hemoglobin-vesicles (CO-HbV). We hypothesized that CO-HbV could have a therapeutic effect on idiopathic pulmonary fibrosis (IPF), an incurable lung fibrosis, that is thought to involve inflammation and the production of reactive oxygen species (ROS). Pulmonary fibril formation and respiratory function were quantitatively evaluated by measuring hydroxyproline levels and forced vital capacity, respectively, using a bleomycin-induced pulmonary fibrosis mice model. CO-HbV suppressed the progression of pulmonary fibril formation and improved respiratory function compared to saline and HbV. The suppressive effect of CO-HbV on pulmonary fibrosis can be attributed to a decrease in ROS generation by inflammatory cells, NADPH oxidase 4 and the production of inflammatory cells, cytokines and transforming growth factor-β in the lung. This is the first demonstration of the inhibitory effect of CO-HbV on the progression of pulmonary fibrosis via the anti-oxidative and anti-inflammatory effects of CO in the bleomycin-induced pulmonary fibrosis mice model. CO-HbV has the potential for use in the treatment of, not only IPF, but also a variety of other ROS and inflammation-related disorders.  相似文献   
53.
 We screened DNAs from 48 Japanese individuals for single-nucleotide polymorphisms (SNPs) in genes encoding 13 cytochrome P450 (CYP) enzymes and 14 aldehyde dehydrogenases (ALDHs) by directly sequencing their entire genomic regions except for repetitive elements. This approach identified 810 SNPs and 96 insertion/deletion polymorphisms among the 27 genes. Of the 810 SNPs, 229 were identified among the CYP genes and 581 in the ALDH genes; of the total, 48 SNPs were located in 5′ flanking regions, 619 in introns, 91 in exons, and 52 in 3′ flanking regions. These variants should contribute to studies designed to investigate possible correlations between genotypes and phenotypes of disease susceptibility or responsiveness to drug therapy. Received: April 23, 2002 / Accepted: April 25, 2002  相似文献   
54.
We examined the role of cell surface clustering of beta2-integrin caused by protein kinase C (PKC)-activated-cPLA2 in adhesion of eosinophilic AML14.3D10 (AML) cells. Phorbol 12-myristate 13-acetate (PMA) caused time- and concentration-dependent adhesion of AML cells to plated bovine serum albumin (BSA), which was blocked by anti-CD11b or anti-CD18 monoclonal antibodies (mAb) directed against beta2-integrin. Inhibition of PKC with Ro-31-8220 or rottlerin blocked PMA-induced cell adhesion in a concentration-dependent fashion. Inhibition of cytosolic phospholipase A2 (cPLA2) with trifluoromethyl ketone or methyl arachidonyl fluorophosphonate also blocked PMA-induced cell adhesion. PMA caused time-dependent p42/44 mitogen-activated protein kinase (MAPK) (ERK) phosphorylation in these cells. U0126, a MAPK/extracellular signal-regulated protein kinase kinase (MEK) inhibitor, at the concentrations that blocked PMA-induced ERK phosphorylation, had no effect on PMA stimulated AML cell adhesion. Neither p38 MAPK nor c-Jun N-terminal kinase (JNK) was phosphorylated by PMA. PMA also caused increased cPLA2 activity, which was inhibited by Ro-31-8220, but not U0126. Confocal immunofluorescence microscopy showed that PMA caused clustering of CD11b on the cell surface, which was blocked by either PKC or cPLA2 inhibition. PMA stimulation also caused up-regulation of CD11b on the AML cell surface. However, this up-regulation was not affected by cPLA2- or PKC-inhibition. Using the mAb, CBRM1/5, we also demonstrated that PMA does not induce the active conformation of CD11b/CD18. Our data indicate that PMA causes AML cell adhesion through beta2-integrin by PKC activation of cPLA2. This pathway is independent of MEK/ERK and does not require change of CD11b/CD18 to its active conformation. We find that avidity caused by integrin surface clustering - rather than conformational change or up-regulation of CD11b/CD18 - causes PMA stimulated adhesion of AML cells.  相似文献   
55.
Central nervous control of micturition and urine storage.   总被引:3,自引:0,他引:3  
The micturition reflex is one of the autonomic reflexes, but the release of urine is regulated by voluntary neural mechanisms that involve centers in the brain and spinal cord. The micturition reflex is a bladder-to-bladder contraction reflex for which the reflex center is located in the rostral pontine tegmentum (pontine micturition center: PMC). There are two afferent pathways from the bladder to the brain. One is the dorsal system and the other is the spinothalamic tract. Afferents to the PMC ascend in the spinotegmental tract, which run through the lateral funiculus of the spinal cord. The efferent pathway from the PMC also runs through the lateral funiculus of the spinal cord to inhibit the thoracolumbar sympathetic nucleus and the sacral pudendal nerve nucleus, while promoting the activity of the sacral parasymapathetic nucleus. Inhibition of the sympathetic nucleus and pudendal nerve nucleus induces relaxation of the bladder neck and the external urethral sphincter, respectively. There are two centers that inhibit micturition in the pons, which are the pontine urine storage center and the rostral pontine reticular formation. In the lumbosacral cord, excitatory glutamatergic and inhibitory glycinergic/GABAergic neurons influence both the afferent and efferent limbs of the micturition reflex. The activity of these neurons is affected by the pontine activity. There are various excitatory and inhibitory areas co-existing in the brain, but the brain has an overall inhibitory effect on micturition, and thus maintains continence. For micturition to occur, the cerebrum must abate its inhibitory influence on the PMC.  相似文献   
56.
Group A rotavirus (RVA) is a major cause of acute gastroenteritis in infants and young children worldwide. This study aims to clarify the distribution of G/P types and genetic characteristics of RVAs circulating in Thailand. Between January 2014 and September 2016, 1867 stool specimens were collected from children and adults with acute gastroenteritis in six provinces in Thailand. RVAs were detected in 514/1867 (27.5%) stool specimens. G1P[8] (44.7%) was the most predominant genotype, followed by G3P[8] (33.7%), G2P[4] (11.5%), G8P[8] (7.0%), and G9P[8] (1.3%). Unusual G3P[9] (0.8%), G3P[10] (0.4%), G4P[6] (0.4%), and G10P[14] (0.2%) were also detected at low frequencies. The predominant genotype, G1P[8] (64.4%), in 2014 decreased to 6.1% in 2016. In contrast, the frequency of G3P[8] markedly increased from 5.5% in 2014 to 65.3% in 2015 and 89.8% in 2016. On polyacrylamide gel electrophoresis, most (135/140; 96.4%) of the G3P[8] strains exhibited a short RNA profile. Successful determination of the nucleotide sequences of the VP7 genes of 98 G3P[8] strains with a short RNA profile showed that they are all equine-like G3P[8] strains. On phylogenetic analysis of genome segments of two representative Thai equine-like G3P[8] strains, it was noteworthy that they possessed distinct NSP4 genes, one bovine-like and the other human-like. Thus, we found that characteristic equine-like G3P[8] strains with a short RNA electropherotype are becoming highly prevalent in children and adults in Thailand.  相似文献   
57.
The striatonigral and olivopontocerebellar systems are known to be vulnerable in multiple system atrophy (MSA), showing neuronal loss, astrogliosis, and alpha-synuclein-immunoreactive inclusions. MSA patients who displayed abundant neuronal cytoplasmic inclusions (NCIs) in the regions other than the striatonigral or olivopontocerebellar system have occasionally been diagnosed with variants of MSA. In this study, we report clinical and pathologic findings of MSA patients characterized by prominent pathologic involvement of the hippocampus. We assessed 146 consecutively autopsied MSA patients. Semi-quantitative analysis of anti-alpha-synuclein immunohistochemistry revealed that 12 of 146 patients (8.2%) had severe NCIs in two or more of the following areas: the hippocampal granule cells, cornu ammonis areas, parahippocampal gyrus, and amygdala. In contrast, the remaining 134 patients did not show severe NCIs in any of these regions. Patients with severe hippocampal involvement showed a higher representation of women (nine women/three men; Fisher's exact test, p = 0.0324), longer disease duration (13.1 ± 5.9 years; Mann–Whitney U-test, p = 0.000157), higher prevalence of cognitive impairment (four patients; Fisher's exact test, p = 0.0222), and lower brain weight (1070.3 ± 168.6 g; Mann–Whitney U-test, p = 0.00911) than other patients. The hippocampal granule cells and cornu ammonis area 1/subiculum almost always showed severe NCIs. The NCIs appeared to be ring-shaped or neurofibrillary tangle-like, fibrous configurations. Three of 12 patients also had dense, round-shaped NCIs that were morphologically similar to pick bodies. The patients with Pick body-like inclusions showed more severe atrophy of the medial temporal lobes and broader spreading of NCIs than those without. Immunohistochemistry for hyperphosphorylated tau and phosphorylated TDP-43 revealed minimal aggregations in the hippocampus of the hippocampal MSA patients. Our observations suggest a pathological variant of MSA that is characterized by severe involvement of hippocampal neurons. This phenotype may reinforce the importance of neuronal alpha-synucleinopathy in the pathogenesis of MSA.  相似文献   
58.
Bacteroides forsythus is a gram-negative, anaerobic, fusiform bacterium and is considered to be an etiological agent in periodontal disease. A lipoprotein fraction prepared from B. forsythus cells by Triton X-114 phase separation (BfLP) activated human gingival fibroblasts and a human monocytic cell line, THP-1, to induce interleukin-6 production and tumor necrosis factor alpha production. BfLP was found to be capable of inducing nuclear factor-kappaB translocation in human gingival fibroblasts and THP-1 cells. By using Chinese hamster ovary K1 cells transfected with Toll-like receptor genes together with a nuclear factor-kappaB-dependent CD25 reporter plasmid, it was found that signaling by BfLP was mediated by Toll-like receptor 2 but not by CD14 or Toll-like receptor 4. BfLP induced apoptotic cell death in human gingival fibroblasts, KB cells (an oral epithelial cell line), HL-60 cells (a human myeloid leukemia cell line), and THP-1 cells but not in MOLT4 cells (a T-cell leukemia cell line). Caspase-8, an initiator caspase in apoptosis, was found to be activated in these cells in response to BfLP stimulation. Thus, this study suggested that BfLP plays some etiological roles in oral infections, especially periodontal disease, by induction of cell activation or apoptosis.  相似文献   
59.
60.
Dendritic cells (DCs) are potent antigen presenting cells and possess a direct anti-tumor cytotoxic ability. Nevertheless, the mechanism of anti-tumor cytotoxicity by DCs and the methods for its evaluation are not fully elucidated. In order to clarify this mechanism of cytotoxicity, we examined the ability of DCs 1) to suppress [3H] thymidine (3H-TdR) uptake by tumor cells; 2) to induce cytolysis on 51Cr-labeled tumor cells; 3) and to induce DNA fragmentation on 3H-TdR labeled tumor cells (JAM test). Cytolysis and DNA fragmentation are markers of necrotic and apoptotic mechanisms of cytotoxicity in vitro, respectively. DCs inhibited approximately 38.6% to 54.8% of the growth of B4D6, NB4, U937, and Daudi cells as evaluated by the uptake of 3H-TdR. However no cytolysis was verified by 51Cr-release assay. On the other hand, cytotoxicity rates found using the JAM test ranged from 3 to 81% depending on the cell line and the effector to target cell ratio. The discrepancy of cytotoxicity between 51Cr-release assay and the JAM test may be due to the phagocytosis of apoptotic tumor cells or the absorption of released 51Cr by DCs surrounding the target cells. In conclusion, the JAM test was more sensitive than the 4-h and the 10-h 51Cr-release assay to investigate cytotoxicity mediated by DCs toward hematopoietic tumor cell lines in vitro.  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