全文获取类型
收费全文 | 2029749篇 |
免费 | 134380篇 |
国内免费 | 4199篇 |
专业分类
耳鼻咽喉 | 25489篇 |
儿科学 | 66356篇 |
妇产科学 | 53516篇 |
基础医学 | 281873篇 |
口腔科学 | 55949篇 |
临床医学 | 173110篇 |
内科学 | 400512篇 |
皮肤病学 | 44062篇 |
神经病学 | 160823篇 |
特种医学 | 76409篇 |
外国民族医学 | 244篇 |
外科学 | 303719篇 |
综合类 | 41967篇 |
现状与发展 | 4篇 |
一般理论 | 569篇 |
预防医学 | 161692篇 |
眼科学 | 47584篇 |
药学 | 146290篇 |
7篇 | |
中国医学 | 5719篇 |
肿瘤学 | 122434篇 |
出版年
2021年 | 15802篇 |
2019年 | 16808篇 |
2018年 | 44771篇 |
2017年 | 33817篇 |
2016年 | 37243篇 |
2015年 | 23583篇 |
2014年 | 31233篇 |
2013年 | 45305篇 |
2012年 | 70044篇 |
2011年 | 85945篇 |
2010年 | 55372篇 |
2009年 | 45407篇 |
2008年 | 78493篇 |
2007年 | 84368篇 |
2006年 | 65604篇 |
2005年 | 63912篇 |
2004年 | 62592篇 |
2003年 | 60252篇 |
2002年 | 56446篇 |
2001年 | 96906篇 |
2000年 | 99415篇 |
1999年 | 81348篇 |
1998年 | 20726篇 |
1997年 | 18003篇 |
1996年 | 18004篇 |
1995年 | 17301篇 |
1994年 | 15772篇 |
1993年 | 14432篇 |
1992年 | 59815篇 |
1991年 | 57515篇 |
1990年 | 55198篇 |
1989年 | 52676篇 |
1988年 | 47977篇 |
1987年 | 46686篇 |
1986年 | 43967篇 |
1985年 | 41601篇 |
1984年 | 30520篇 |
1983年 | 25928篇 |
1982年 | 14445篇 |
1979年 | 26910篇 |
1978年 | 18460篇 |
1977年 | 15726篇 |
1976年 | 14660篇 |
1975年 | 15527篇 |
1974年 | 18981篇 |
1973年 | 18231篇 |
1972年 | 16873篇 |
1971年 | 15631篇 |
1970年 | 14602篇 |
1969年 | 13737篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
D. Lothschütz M. Jennewein S. Pahl H.F. Lausberg A. Eichler W. Mutschler R.G. Hanselmann M. Oberringer 《Inflammation research》2002,51(8):416-422
OBJECTIVE AND DESIGN: Inflammatory and tumorous bronchi were screened in order to obtain new tumor relevant cytogenetic parameters. MATERIAL OR SUBJECTS: Bronchial cells of 32 patients were cultivated by standard cell culture procedures. METHODS: Tetraploidy and aneuploidy was determined by enumeration of chromosome 7 and 8 versus the number of centrosomes. The resulting data were correlated with histopathological data. RESULTS: Tetra- and aneuploidy of epithelial cells were detectable in 76% of tumor cell cultures, 75% of high grade inflammatory tissues and 40% of non- and low grade-inflammatory tissues. Additionally, we observed centrosome hyper-amplification and multipolar mitoses not only in the tumor but also in the early stages of inflammation. CONCLUSION: Inflammatory bronchi already show tumor-specific features and may consequently represent the preliminary genetic stage of cancer development in bronchi. 相似文献
972.
973.
974.
975.
B. Tutluolu S. At A. N. Anakkaya E. Altu G. A. Tosun M. Yaman 《Clinical and experimental allergy》2002,32(8):1170-1173
OBJECTIVE: This study aimed to investigate the rate of occupational sensitization to horse hair in grooms and whether occupational exposure to horse hair increases respiratory and allergic symptoms and affects lung function in grooms or not. METHODS: This is a cross-sectional study. Two hundred grooms were randomly selected among 1000 grooms working in Veliefendi Hippodrome of Istanbul. One hundred and twenty-five subjects agreed to enter the study. Ninety-two workers who worked in the different parts of this hippodrome enrolled as the control group. A detailed questionnaire including respiratory and allergic symptoms was filled in, physical examination, skin prick tests and pulmonary function tests were performed. RESULTS: Sensitization to horse hair was 12.8% in grooms and 4.3% in controls. The difference was statistically significant (P = 0.0035). Asthma was found in 14.4% of the grooms and 5.4% of the controls, allergic rhinitis in 42.4% of the grooms and 18.4% of the controls, allergic conjunctivitis in 35.2% of the grooms and 15.2% of the controls, and allergic skin diseases in 32.8% of the grooms and 13% of the controls. The differences were statistically significant (P = 0.043, P = 0.0002, P = 0.001 and P = 0.0008, respectively). The means of FEV1, FEV1/FVC and FVC parameters were significantly lower in the groom group (P = 0.006, P = 0.001 and P = 0.003, respectively). In the multivariate analysis, being in the groom group and working years were found to be predictive factors for impairments of lung function (P < 0.001 and P = 0.002, respectively). CONCLUSION: Occupational exposure to horse increases the sensitization to horse hair, induces asthma and allergic symptoms and also impairs lung functions. 相似文献
976.
A. O. Azghani J. W. Baker S. Shetty E. J. Miller G. J. Bhat 《Inflammation research》2002,51(10):506-510
OBJECTIVE AND DESIGN: Bacterial products as well as the host airway inflammatory responses contribute to the pathogenesis of Pseudomonas infections. We sought to determine if Pseudomonas elastase (PE) induces mitogen-activated protein (MAP) kinase activity in association with interleukin-8 (IL-8) production by alveolar epithelial cells. METHODS: We utilized Western blot analysis to detect phosphorylation of signaling intermediates and ELISA was used to measure IL-8 production. RESULTS: We found that PE induces phosphorylation of the extracellular signal-regulated (ERK1/2) proteins of the MAPK pathway in A549 epithelial cells. Similar results were obtained using primary cultures of rabbit alveolar type II epithelial cells. PE also enhanced IL-8 production, which was abolished in the presence of the ERK activation inhibitor U0126. CONCLUSIONS: We conclude that PE activates the ERK1/2 arm of the MAPK pathway and that activation of this pathway results in enhanced IL-8 production. The results demonstrate that PE may augment pulmonary inflammation via cellular signaling that regulates expression of IL-8. 相似文献
977.
978.
Neutrophil defensins stimulate the release of cytokines by airway epithelial cells: modulation by dexamethasone 总被引:5,自引:0,他引:5
S. van Wetering S. P. G. Mannesse-Lazeroms M. A. J. A. van Sterkenburg P. S. Hiemstra 《Inflammation research》2002,51(1):8-15
OBJECTIVE AND DESIGN: Neutrophils may contribute to recruiting other cells to sites of inflammation by generating chemotactic signals themselves, or by stimulating other cell types to release chemoattractants such as interleukin-8 (IL-8). Recently, we demonstrated that neutrophil-derived alpha-defensins are able to increase IL-8 expression in airway epithelial cells. In addition, it has previously been reported that neutrophil elastase-induced IL-8 synthesis was insensitive to inhibition by the glucocorticoid dexamethasone. The aim of the present study was to investigate the effect of defensins on the expression of various cytokines in cultured airway epithelial cells and to examine the effect of dexamethasone on defensin-induced cytokine synthesis in these cells. METHODS: Cultures of A549 cells and primary bronchial epithelial cells (PBEC) were stimulated with defensins either alone or in the presence of dexamethasone. Supernatants were analyzed for IL-8, ENA-78, IL-6, MCP-1 and GM-CSF by ELISA. In addition, IL-8 and ENA-78 mRNA was detected by Northern blot analysis. RESULTS: Defensins increased IL-8 expression, ENA-78, MCP-1 and GM-CSF release from A549 cells, whereas in PBEC only IL-8 and IL-6 were increased. Pre-treatment with dexamethasone significantly reduced defensin-induced IL-6, IL-8 and ENA-78 synthesis in airway epithelial cells. In addition, dexamethasone also reduced the neutrophil chemotactic activity in supernatants of these cells. CONCLUSIONS: The results from the present study indicate that defensins differentially induce cytokine secretion by A549 cells and PBEC. Glucocorticoids may interfere with the defensin-induced inflammatory process by reducing defensin-induced cytokine secretion in lung epithelial cells. 相似文献
979.
Previously, we prepared two different monoclonal antibodies (mAbs) against human 4-1BB (CD137): an agonistic mAb BBK-1 and an antagonistic mAb BBK-2. In this paper, we describe the molecular cloning of these two mAbs and present comparisons of their amino acid sequences. cDNAs encoding the heavy (H) and light (L) chains of the two mAbs were cloned by screening of cDNA libraries constructed from hybridomas secreting these mAbs. Comparisons of amino acid sequences of the two mAbs showed that, while the constant regions of the H and L chains were identical between the two mAbs, the variable region showed 45% identity in H chains and 48% identity in L chains. This suggests that these two mAbs recognize different epitopes of 4-1BB and may have different effects on the activity of 4-1BB. 相似文献
980.
We describe a simple direct extraction method for the gas-liquid chromatography determination of serum valproic acid. The working range for the assay is 2-180 mg/L and our within-run precision was 5.8 and 4.3% at the 40 and 90 mg/L concentrations respectively. Hemolyzed and lipemic sera as well as samples from patients with hyperbilirubinemia and from patients with decreased renal function were put through the assay and no interfering peaks were noted. Interference occurred when teflon-lined screw caps were used during the extraction step. The method was proven to be accurate by linear regression analysis of samples containing weighed-in amounts of valproic acid. The above assay was compared to an enzyme immunoassay technique (EMIT). The working range for the latter is 10-150 mg/L and the with-run precision was 10.8 and 5.9% and 90 mg/L concentration respectively. Samples were run by both the gas-liquid chromatograph and enzyme immunoassay methods and gave very similar results over the range 16-139 mg/L. 相似文献