全文获取类型
收费全文 | 5273篇 |
免费 | 251篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 47篇 |
儿科学 | 125篇 |
妇产科学 | 56篇 |
基础医学 | 583篇 |
口腔科学 | 161篇 |
临床医学 | 376篇 |
内科学 | 1264篇 |
皮肤病学 | 51篇 |
神经病学 | 363篇 |
特种医学 | 203篇 |
外科学 | 913篇 |
综合类 | 19篇 |
预防医学 | 298篇 |
眼科学 | 64篇 |
药学 | 539篇 |
中国医学 | 9篇 |
肿瘤学 | 469篇 |
出版年
2023年 | 23篇 |
2022年 | 48篇 |
2021年 | 95篇 |
2020年 | 44篇 |
2019年 | 60篇 |
2018年 | 81篇 |
2017年 | 74篇 |
2016年 | 75篇 |
2015年 | 74篇 |
2014年 | 112篇 |
2013年 | 157篇 |
2012年 | 226篇 |
2011年 | 267篇 |
2010年 | 142篇 |
2009年 | 87篇 |
2008年 | 192篇 |
2007年 | 232篇 |
2006年 | 213篇 |
2005年 | 240篇 |
2004年 | 224篇 |
2003年 | 197篇 |
2002年 | 218篇 |
2001年 | 203篇 |
2000年 | 190篇 |
1999年 | 187篇 |
1998年 | 64篇 |
1997年 | 59篇 |
1996年 | 56篇 |
1995年 | 47篇 |
1994年 | 55篇 |
1993年 | 55篇 |
1992年 | 171篇 |
1991年 | 166篇 |
1990年 | 140篇 |
1989年 | 128篇 |
1988年 | 119篇 |
1987年 | 104篇 |
1986年 | 111篇 |
1985年 | 110篇 |
1984年 | 60篇 |
1983年 | 59篇 |
1982年 | 30篇 |
1981年 | 28篇 |
1980年 | 23篇 |
1979年 | 44篇 |
1975年 | 24篇 |
1974年 | 27篇 |
1971年 | 21篇 |
1969年 | 20篇 |
1968年 | 20篇 |
排序方式: 共有5540条查询结果,搜索用时 15 毫秒
41.
Activation of protease-activated receptor 2 stimulates proliferation and interleukin (IL)-6 and IL-8 secretion of endometriotic stromal cells 总被引:3,自引:0,他引:3
Hirota Y Osuga Y Hirata T Harada M Morimoto C Yoshino O Koga K Yano T Tsutsumi O Taketani Y 《Human reproduction (Oxford, England)》2005,20(12):3547-3553
BACKGROUND: Inflammation has been proposed to play essential roles in the pathophysiology of endometriosis, in which neutrophils and mast cells have been suggested to be involved. We studied whether the protease-activated receptor 2 (PAR2), which is activated by enzymes from neutrophils and mast cells, in endometriotic stromal cells (ESC) has any implication in the development of the disease. METHODS: Cultured ESC were stimulated with various concentrations of a specific PAR2 agonist peptide. Proliferating activity of the cells was determined using immunostaining of proliferating cell nuclear antigen (a cell proliferation marker), 5-bromo-2'-deoxyuridine incorporation into DNA and cell count. The concentrations of interleukin (IL)-6 and IL-8 were measured using specific enzyme-linked immunosorbent assay kits. The phosphorylation of three mitogen-activated protein kinases (MAPK), i.e. p38 MAPK, p42/44 MAPK and stress-activated protein Kinase/c-jun N terminal Kinase, in ESC was examined with Western blot analysis. RESULTS: Activation of PAR2 stimulated the proliferation of ESC and the secretion of IL-6 and IL-8 from ESC in a dose-dependent manner. Activation of PAR2 stimulated the phosphorylation of all three MAPK, and inhibitors of each MAPK suppressed the PAR2 activation-induced proliferation of ESC. CONCLUSIONS: The activation of PAR2 in ESC may be involved in the pathophysiology of endometriosis by inducing the growth and inflammation of endometriotic lesions. 相似文献
42.
Yozo Miura Yuzo Morimoto Masayoshi Kinoshita 《Macromolecular chemistry and physics.》1974,175(12):3487-3493
2,4,6-Triphenyl-3,4-dihydro-s-tetrazin-1(2H)-yl ( 1 ) (1,3,5-triphenylverdazyl) was allowed to react with ethyl- and butyllithium, ethyl-, isopropyl-, and butylmagnesium bromide, as well as benzylmagnesium chloride to give the coupling products 2a–d . These results indicate that structures corresponding to 2 are present in the polymers resulting from vinyl monomers containing the verdazyl structure, if they are initiated with alkyllithium or a Grignard reagent. A reaction mechanism is discussed. 相似文献
43.
Fujita M Ishihara M Simizu M Obara K Ishizuka T Saito Y Yura H Morimoto Y Takase B Matsui T Kikuchi M Maehara T 《Biomaterials》2004,25(4):699-706
Addition of various heparinoids to the lactose-introduced, water-soluble chitosan (CH-LA) aqueous solution produces an injectable chitosan/heparinoid hydrogel. In the present work, we examined the capability of the chitosan/non-anticoagulant heparin (periodate-oxidized (IO(4)-) heparin) hydrogel to immobilize fibroblast growth factor (FGF)-2, as well as the controlled release of FGF-2 molecules from the hydrogel in vitro and in vivo. The hydrogel was biodegraded in about 20 days after subcutaneous injection into the back of a mouse. When the FGF-2-incorporated hydrogel was subcutaneously injected into the back of both mice and rats, a significant neovascularization and fibrous tissue formation were induced near the injected site. These results indicate that the controlled release of biologically active FGF-2 molecules is caused by biodegradation of the hydrogel, and that subsequent induction of the vascularization occurs. 相似文献
44.
Osteopontin affects the persistence of beta-glucan-induced hepatic granuloma formation and tissue injury through two distinct mechanisms 总被引:4,自引:0,他引:4
Morimoto J Inobe M Kimura C Kon S Diao H Aoki M Miyazaki T Denhardt DT Rittling S Uede T 《International immunology》2004,16(3):477-488
Osteopontin (OPN) plays a pivotal role in various immune responses and inflammatory diseases. OPN is expressed in various granulomatous diseases; however, the cellular and molecular role of OPN in these diseases is not well known. We analyzed the role of OPN in a beta-glucan-induced hepatic granuloma model. First, we found that neither OPN deficiency nor overexpression of OPN affected the number and the size of hepatic granulomas at day 7, indicating that OPN is not involved in the formation of hepatic granulomas at the early stages. Importantly, OPN did not influence the liver tissue damage as defined by alanine aminotransferase and aspartate aminotransferase levels at early stages. Second, OPN deficiency resulted in the reduction of IL-12 and IFN-gamma production at early stages. Third, at late stages, OPN deficiency resulted in a decrease in the number and size of hepatic granulomas, and a reduction of liver tissue injury. This was due to the reduction of the cellular recruitment including macrophages, CD4 T cells and dendritic cells into the liver, and the reduction of tumor necrosis factor (TNF)-alpha production in the liver. In contrast, overexpression of OPN resulted in the persistence of granuloma formation. These data suggest that OPN affects the persistence of hepatic granuloma formation. Our results indicate that OPN up-regulates the production of IL-12 and IFN-gamma within the granulomas at early stages, and OPN has an additional role in the regulation of cellular recruitment and TNF-alpha production at late stages that determine the severity of liver tissue injury. 相似文献
45.
46.
The role of functionally distinct helper T lymphocyte subpopulations in the induction of human B cell differentiation 总被引:8,自引:0,他引:8
J W Sleasman C Morimoto S F Schlossman T F Tedder 《European journal of immunology》1990,20(6):1357-1366
Human helper T lymphocytes can be dissected into two functionally distinct subpopulations based on expression of the CD45RA (2H4) or CD45R0 (UCHL-1) surface antigens. While both subpopulations are able to induce equivalent levels of B cell activation and proliferation, only the CD4+CD45RA- subpopulation is capable of inducing B cell differentiation in pokeweed mitogen (PWM)-stimulated cultures. To define the mechanism responsible for the dichotomy between induction of proliferation and differentiation by the two CD4+ subpopulations, we examined the abilities of the purified T cell subpopulations to produce lymphokine mRNA following T cell activation. Northern analysis revealed that both subpopulations produced interleukin (IL) 2 and interferon (IFN)-gamma mRNA following PWM activation. The CD4+CD45RA- subpopulation, however, produced higher levels of IFN-gamma mRNA and the CD4+CD45RA+ cells produced higher levels of IL 2 mRNA. Neither subpopulation elaborated detectable mRNA for IL 4, IL 5 or IL 6. Of greatest significance was that the addition of recombinant or T cell-derived lymphokines could not compensate for the inability of the CD4+CD45RA+ subpopulation to induce B cell differentiation in PWM assays. Direct T-B cell contact was required for the optimal induction B cell differentiation in these assays, suggesting that CD4+CD45RA+ T cells were deficient in their ability to directly deliver the T cell-B cell signals required for B cell differentiation. These results suggest that the differential ability of the two subpopulations of CD4+ T cells to induce B cell differentiation does not result from differences in lymphokines elaborated, but may result from differences in their abilities to interact directly with B cells to initiate differentiation. 相似文献
47.
H Yoshida H Adachi Y Hamada T Aki T Yumoto K Morimoto T Orido 《Acta pathologica japonica》1988,38(3):325-338
The osteosarcomas were subclassified into osteoblastic, fibroblastic, chondroblastic and telangiectatic types and examined by electron microscopy. Their immunohistochemical reactions were also studied. In an overall survey of the above types, fibroblast-like cells revealed poorly developed cytoplasmic organelles with rather short, branching rough endoplasmic reticulum, mixed with osteoblast-like cells that were hardly distinguishable from the former. They appeared to be an early stage of an osteoblastic cell lineage from the distribution and development of their cell organelles and highly positive vimentin activity. The tumor cells in malignant cartilage varied in appearance from chondroblast-like to osteoblast-like cells. All types of tumor cells expressed alkaline phosphatase activity to a significant degree. Immunohistochemical staining showed a mixture of procollagen type I-positive cells among the cells positive for both procollagen type II and S-100 protein in the malignant cartilage. Irrespective of any ultrastructural differences between these various tumor cell types, they all revealed a significant degree of ALPase activity unlike other types of bone tumors, suggesting that the tumor cells which constitute the various types of osteosarcoma are derived from a common precursor cell. 相似文献
48.
Requirements for the development of IL-4-producing T cells during intestinal nematode infections: what it takes to make a Th2 cell in vivo 总被引:1,自引:0,他引:1
Zhugong Liu Qian Liu John Pesce Robert M. Anthony Erika Lamb Jeannette Whitmire Hossein Hamed Motoko Morimoto Joseph F. Urban Jr William C. Gause 《Immunological reviews》2004,201(1):57-74
Summary: Components of the type 2 immune response may mediate host protection against both helminthic parasites and harmful allergic responses. A central player in this response is the T‐helper 2 (Th2) effector cell, which produces interleukin (IL)‐4, IL‐5, IL‐13, and other Th2 cytokines during the primary and memory response. Specific aspects of the parasite that trigger Th2‐cell differentiation are not yet defined. Furthermore, the cell types and cell surface and secreted molecules that provide the immune milieu required for the development of Th2 effector cells and also Th2 memory cells are not well understood. They will probably vary with the particular helminth or other antigen inducing the Th2 response. We have used third stage larvae of intestinal nematode parasites as adjuvants to promote naïve nonparasite antigen‐specific T cells to differentiate into Th2 cells. This model system avoids possible parasite antigen‐specific T‐cell clones or cross‐reactive memory T cells that may preferentially differentiate into Th2 effector cells during the course of infection and confound the stereotypical components of parasite‐induced Th2 cell differentiation. We have found that these parasites have a potent adjuvant effect and have used our model system to begin to investigate the events that lead to the development of polarized Th2 cells in vivo. 相似文献
49.
K Yoshioka T Iseki M Okada Y Morimoto N Eryu S Maki 《Clinical and experimental immunology》1988,74(3):419-424
Goodpasture (GP) antigens, protein components reactive with human autoantibodies against glomerular basement membrane (GBM), were identified in human alveolar basement membrane (ABM) using an enzyme-linked immunoassay (ELISA), Western blotting and immunoprecipitation. All six anti-GBM antisera studied, three obtained from patients with glomerulonephritis and pulmonary haemorrhages (i.e. GP syndrome), and three from patients with glomerulonephritis alone, distinctively reacted with collagenase-digested (CD) ABM. Very cationic 22-28 kD and 40-48 kD components were detected by blot analysis combined with two-dimensional gel electrophoresis. These proteins showed some similarities to GP antigens in human GBM with respect to the monomer-dimer composition and charge distribution. Inhibition ELISA revealed that the binding of anti-GBM antisera to CDGBM decreased when they were pre-incubated with CDABM, suggesting that the anti-GBM antisera recognized the same epitope(s) on the GBM and ABM. Heterogeneity of the GP antigens in human ABM was demonstrated by blotting; monomeric antigens were absent or at low levels in the CDABM of three out of 10 normal individuals. In immunoprecipitation, anti-GBM antisera from patients with and without pulmonary haemorrhage showed different reactivities with CDABM. The former antisera precipitated both monomeric and dimeric components, but the latter did not. The observations of variation in monomer-dimer composition of ABM, and the different binding of anti-GBM antisera to it may explain why only some patients with anti-GBM nephritis have lung involvement. 相似文献
50.
Continuous measurement of fluid mobilization from ICF space following acute dehydration by dialyzation in dogs 总被引:1,自引:0,他引:1
The changes of the distribution of body fluid following acute isotonic dialyzation were studied from the results of continuous monitoring of extracellular fluid volume and physiological parameters. An indicator of extracellular space, 51Cr-EDTA, was injected into splenonephrectomized dogs. After the equilibrium of tracer dilution was attained, 10 ml/kg of plasma water was isotonically withdrawn by means of a dialyzer of hollow fiber type. The volumes of extracellular fluid (ECF) and plasma (PV) were continuously monitored for 80 min and plasma osmolality was measured at 10 min intervals. At the 50-60th min after the fluid modification, the reduction of PV was only 3.8 ml/kg and that of ECF was 4.2 ml/kg. The continuous profile of ECF change showed a significant mobilization of water from intracellular fluid (ICF) soon after the dialyzation. It is concluded that, in the state of hypovolemia, plasma fluid is replenished with the transvascular fluid absorption from interstitial space and that, concomitantly, the reduction of ISF is restituted with the fluid mobilization from ICF into extracellular space within the early stage of 1 hr. Good linear correlation was found between the amount of mobilized water from ICF and the increment of plasma osmolality. An increase in osmotic force was considered the mechanism which caused the fluid shift. These findings suggest that the change in plasma osmolality is a good predictor of mobilized volume from ICF in hypovolemia. The effects of inverse fluid modification, i.e., isotonic infusion, were also compared. 相似文献