全文获取类型
收费全文 | 150855篇 |
免费 | 13165篇 |
国内免费 | 9995篇 |
专业分类
耳鼻咽喉 | 1315篇 |
儿科学 | 1776篇 |
妇产科学 | 2579篇 |
基础医学 | 17528篇 |
口腔科学 | 2385篇 |
临床医学 | 19563篇 |
内科学 | 23929篇 |
皮肤病学 | 1645篇 |
神经病学 | 8175篇 |
特种医学 | 5135篇 |
外国民族医学 | 78篇 |
外科学 | 15944篇 |
综合类 | 24076篇 |
现状与发展 | 27篇 |
一般理论 | 5篇 |
预防医学 | 9472篇 |
眼科学 | 4293篇 |
药学 | 15668篇 |
132篇 | |
中国医学 | 7533篇 |
肿瘤学 | 12757篇 |
出版年
2024年 | 409篇 |
2023年 | 2120篇 |
2022年 | 5491篇 |
2021年 | 6882篇 |
2020年 | 5002篇 |
2019年 | 4756篇 |
2018年 | 4811篇 |
2017年 | 4367篇 |
2016年 | 4096篇 |
2015年 | 6229篇 |
2014年 | 7768篇 |
2013年 | 7373篇 |
2012年 | 10832篇 |
2011年 | 11587篇 |
2010年 | 7334篇 |
2009年 | 5881篇 |
2008年 | 7851篇 |
2007年 | 7945篇 |
2006年 | 7973篇 |
2005年 | 7867篇 |
2004年 | 5569篇 |
2003年 | 5420篇 |
2002年 | 4597篇 |
2001年 | 4081篇 |
2000年 | 4047篇 |
1999年 | 4104篇 |
1998年 | 2560篇 |
1997年 | 2517篇 |
1996年 | 1821篇 |
1995年 | 1709篇 |
1994年 | 1457篇 |
1993年 | 951篇 |
1992年 | 1373篇 |
1991年 | 1200篇 |
1990年 | 1053篇 |
1989年 | 919篇 |
1988年 | 784篇 |
1987年 | 745篇 |
1986年 | 561篇 |
1985年 | 510篇 |
1984年 | 270篇 |
1983年 | 193篇 |
1982年 | 124篇 |
1981年 | 128篇 |
1980年 | 79篇 |
1979年 | 122篇 |
1978年 | 59篇 |
1976年 | 52篇 |
1975年 | 55篇 |
1974年 | 65篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Jinyi Yuan Biwen Mo Zhuang Ma Yuan Lv Shih-Lung Cheng Yanping Yang Zhaohui Tong Renguang Wu Shenghua Sun Zhaolong Cao Jufang Wu Demei Zhu Liwen Chang Yingyuan Zhang 《Journal of microbiology, immunology, and infection》2019,52(1):35-44
Background/Purpose
Nemonoxacin is a novel nonfluorinated quinolone with excellent in vitro activity against most pathogens in community-acquired pneumonia (CAP), especially Gram-positive isolates. The purpose of this study was to assess the efficacy and safety of nemonoxacin compared with levofloxacin in patients with CAP.Methods
A phase 3, multicenter, randomized (2:1) controlled trial was conducted in adult CAP patients receiving nemonoxacin 500 mg or levofloxacin 500 mg orally once daily for 7–10 days. Clinical, microbiological response and adverse events were assessed. Non-inferiority was determined in terms of clinical cure rate of nemonoxacin compared with that of levofloxacin in a modified intention-to-treat (mITT) population. NCT registration number: NCT01529476.Results
A total of 527 patients were randomized and treated with nemonoxacin (n = 356) or levofloxacin (n = 171). The clinical cure rate at test-of-cure visit was 94.3% (300/318) for nemonoxacin and 93.5% (143/153) for levofloxacin in the mITT population [difference (95% CI), 0.9% (?3.8%, 5.5%)]. The microbiological success rate was 92.1% (105/114) for nemonoxacin and 91.7% (55/60) for levofloxacin in the bacteriological mITT population [difference (95% CI), 0.4% (?8.1%, 9.0%)]. The incidence of adverse events (AEs) was comparable between nemonoxacin (33.1%, 118/356) and levofloxacin (33.3%, 57/171) (P > 0.05).Conclusion
Nemonoxacin 500 mg once daily for 7–10 days is as effective and safe as levofloxacin for treating adult CAP patients in terms of clinical cure rates, microbiological success rates, and safety profile.ClinicalTrials.gov identifier: NCT01529476. 相似文献992.
目的 观察缺血再灌注后加用NO供体对肾脏ICAM-1表达及白细胞浸润的影响。方法 分别采用ICAM-1和整合素β2多克隆抗体,免疫组化方法观察加有NO供体后大鼠肾脏缺血再灌注24hICAM-1表达的变化及肾功能改变。结果 缺血再灌注24h大鼠肾脏ICAM-1及β2阳性细胞表达显著增强,以外髓直小血管,皮质肾小管外毛细血管较为明显,再灌注同时灌注NO供体SIN-1可显著抑制缺血再灌注后ICAM-1的表达增强,减少局部炎细胞浸润,改善肾功能,结论 NO供体可减少肾组织ICAM-1的表达及炎细胞浸润,发挥对急性缺血性肾衰的治疗作用。 相似文献
993.
Social isolation stress augments angiogenesis induced by colon 26-L5 carcinoma cells in mice 总被引:3,自引:0,他引:3
Wu W Murata J Murakami K Yamaura T Hayashi K Saiki I 《Clinical & experimental metastasis》2000,18(1):1-10
We have previously shown that tumor necrosis factor-α (TNF-α), which is an important angiogenesis-related factor, was over-secreted in male BALB/c mice under social isolation stress as compared with the control, and closely associated with a remarkable elevation of tumor invasion and metastasis of colon 26-L5 carcinoma cells. In the present study, we explored the effect of isolation stress on the angiogenesis caused by colon 26-L5 carcinoma cells in vivo and in vitro. Social isolation lead to the enhancement of tumor growth after intrahepatic implantation with a fragment of colon 26-L5 tumor. Angiogenic response (number of vessels oriented towards tumor mass) and tumor growth (size) were significantly increased in the socially isolated mouse relative to that in the group-housed mice. Furthermore, higher protein level of hepatic TNF-α was found in the stressed mice than that in the control. Expression of mRNA for vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were also elevated in the tumor regions and liver tissues of the stressed mice in comparison with that in group-housed mice. On the other hand, hepatic sinusoidal endothelial (HSE) cells treated with TNF-α exhibited a marked promotion of the migration, invasion, expression of mRNA for matrix metalloproteinase (MMP)-9, and tube-like formation, but no cytotoxicity against the cells in vitro. The above data suggest that the social isolation stress augmented the tumor-induced angiogenesis probably by up-regulating the angiogenesis-related factors, including TNF-α, VEGF and HGF, and consequently mediating the functions of endothelial cells such as migration, invasion, and tube-like formation. 相似文献
994.
Several genetic mouse models of differential sensitivity to opioids have been used to investigate the mechanisms underlying individual variation in responses to opioids. The CXBK mice are inbred recombinant mice which have a lower level of mu(1)-opioid receptors than their parental strain. Endomorphin-1 and endomorphin-2 are endogenous opioid peptides that are highly selective for mu-opioid receptors, while beta-endorphin, which is also an endogenous opioid peptide, is non-selective for mu-, delta- and putative epsilon-opioid receptors. The present study was designed to investigate the effects of these endogenous opioid peptides on G-protein activation by monitoring guanosine-5'-o-(3-[35S]thio)triphosphate binding to pons/medulla membranes of CXBK mice and their parental strain C57BL/6 ByJ mice. Endomorphin-1 (0.1-10 microM), endomorphin-2 (0.1-10 microM) and beta-endorphin (0.1-10 microM) increased guanosine-5'-o-(3-[35S]thio)triphosphate binding to the pons/medulla membranes from C57BL/6 ByJ and CXBK mice in a concentration-dependent manner. However, the increases of guanosine-5'-o-(3-[35S]thio)triphosphate binding induced by either endomorphin-1 or endomorphin-2 in CXBK mice were significantly much lower than those in C57BL/6ByJ mice. However, no significant difference was found in the increases of the guanosine-5'-o-(3-[35S]thio)triphosphate binding induced by beta-endorphin in C57BL/6 ByJ and CXBK mice. Moreover, whereas the increase of guanosine-5'-o-(3-[35S]thio)triphosphate binding induced by 10 microM endomorphin-1 or endomorphin-2 were almost completely blocked by a mu-opioid receptor antagonist beta-funaltrexamine (10 microM) in both strains, the increase of guanosine-5'-o-(3-[35S]thio)triphosphate binding induced by 10 microM beta-endorphin was attenuated to approximately 70% of stimulation by co-incubation with 10 microM beta-funaltrexamine in both strains. The residual stimulation of [35S]guanosine-5'-o-(3-thio)triphosphate binding by 10 microM beta-endorphin in the presence of 10 microM beta-funaltrexamine was further attenuated by the addition of putative epsilon-opioid receptor partial agonist beta-endorphin (1-27) (1 microM) in both strains. Like the endomorphins, the synthetic mu-opioid receptor agonist [D-Ala(2),N-MePhe(4), Gly-ol(5)]enkephalin at 10 microM showed lower increases of guanosine-5'-o-(3-[35S]thio)triphosphate binding in CXBK mice than those in C57BL/6ByJ mice. However, there was no strain difference in the stimulation of guanosine-5'-o-(3-[35S]thio)triphosphate binding induced by 10 microM of the selective delta(1)-opioid receptor agonist [D-Pen(2,5)]enkephalin, delta(2)-opioid receptor agonist [D-Ala(2)]deltorphin II or kappa-opioid receptor agonist U50,488H. The results indicate that the G-protein activation by endomorphin-1 and endomorphin-2 in the mouse pons/medulla is mediated by both mu(1)- and mu(2)-opioid receptors. Moreover, beta-endorphin-induced G-protein activation in the mouse pons/medulla is, in part, mediated by mu(2)- and putative epsilon-, but not by mu(1)-opioid receptors. 相似文献
995.
乙醇对人绒毛孕酮分泌的影响 总被引:1,自引:0,他引:1
本工作利用灌流技术观察了四种不同浓度的乙醇(0.5%、1%、2.5%、5%)对妊娠早期人工流产新鲜胎盘绒毛分泌孕酮的影响。结果表明,乙醇具有促进孕酮分泌的作用,并存在剂量依赖的关系。提示乙醇可能破坏胎盘激素内分泌的平衡,从而影响胎儿的正常生长与发育。 相似文献
996.
Shieh WJ Hsiao CH Paddock CD Guarner J Goldsmith CS Tatti K Packard M Mueller L Wu MZ Rollin P Su IJ Zaki SR 《Human pathology》2005,36(3):303-309
This article describes the pathological studies of fatal severe acute respiratory syndrome (SARS) in a 73-year-old man during an outbreak of SARS in Taiwan, 2003. Eight days before onset of symptoms, he visited a municipal hospital that was later identified as the epicenter of a large outbreak of SARS. On admission to National Taiwan University Hospital in Taipei, the patient experienced chest tightness, progressive dyspnea, and low-grade fever. His condition rapidly deteriorated with increasing respiratory difficulty, and he died 7 days after admission. The most prominent histopathologic finding was diffuse alveolar damage of the lung. Immunohistochemical and in situ hybridization assays demonstrated evidence of SARS-associated coronavirus (SARS-CoV) infection in various respiratory epithelial cells, predominantly type II pneumocytes, and in alveolar macrophages in the lung. Electron microscopic examination also revealed coronavirus particles in the pneumocytes, and their identity was confirmed as SARS-CoV by immunogold labeling electron microscopy. This report is the first to describe the cellular localization of SARS-CoV in human lung tissue by using a combination of immunohistochemistry, double-stain immunohistochemistry, in situ hybridization, electron microscopy, and immunogold labeling electron microscopy. These techniques represent valuable laboratory diagnostic modalities and provide insights into the pathogenesis of this emerging infection. 相似文献
997.
Factors affecting the outcome of distal realignment for patellofemoral disorders of the knee 总被引:1,自引:0,他引:1
This study correlated the risk factors with the clinical outcome of distal realignment for patellofemoral disorders in 48 patients with 53 knees with 25 to 96 months follow-up. The indications for surgery included pain and disability due to patellofemoral disorders with failure of at least 6 months of conservative treatments. The evaluations included pain scores, Lysholm functional scores and radiographs of the knee. The overall results were satisfactory in 47 knees (88.7%) and unsatisfactory in six knees (11.3%). There was no correlation of the clinical results with age, sex, body weight and body height, preoperative pain scores and Lysholm scores. However, the clinical outcome correlated with the severity of articular damage and the correction of patellar malalignment. Error in patient selection and inadequate surgical technique were attributable to poor outcomes. 相似文献
998.
Na?Wang Qiu-Liang?Wu Yan?Fang Hai-Qiang?Mai Mu-Sheng?Zeng Guo-Ping?Shen Jing-Hui?Hou Yi-Xin?ZengEmail author 《Journal of translational medicine》2005,3(1):26
Nasopharyngeal carcinoma (NPC) is a tumor derived from epithelial cells and Epstein-Barr virus infection has been reported
to be a cause of this disease. Chemokine receptor CXCR4 was found to be involved in HIV infection and was highly expressed
in human malignant breast tumors and the ligand for CXCR4, CXCL12 (SDF-1), exhibited high expression in organs in which breast
cancer metastases are often found. The metastatic pattern of NPC is quite similar to that of malignant breast tumors. In this
study, we investigated the expression of CXCR4 in nasopharyngeal carcinoma (NPC) tissues by immunohistostaining. We found
different staining patterns, which included localization in the nucleus, membrane, cytoplasm or a combination of them. The
staining intensity was also variable among samples. The metastatic rates in patients with high compared to low or absent expression
was 38.6% versus 19.8%, respectively (P = 0.004). High expression of CXCR4 was associated with poor overall survival (OS = 67.05% versus 82.08%, P = 0.0225). These results suggest that CXCR4 may be involved in the progression of NPC and that a high level of CXCR4 expression
could be used as a prognostic factor. 相似文献
999.
研究了长序列心电信号的最佳复杂度。先将原始序列符号化 ,再采用 L empel- Ziv算法来计算复杂度 ,探讨影响复杂度的各种因素 ,然后对三组不同信号即正常心电、心绞痛和心肌梗塞信号进行分析。结果表明 ,采用最佳阈值比用平均值为阈值得到的复杂度更能明显地分辨出正常和异常信号 ,原始序列符号化的阈值以及信号长度直接影响序列复杂度 ,因此 ,在实际信号的复杂度测量上 ,应采用最佳阈值和最佳信号长度。 相似文献
1000.
Fundic gland polyps in familial adenomatous polyposis: neoplasms with frequent somatic adenomatous polyposis coli gene alterations 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Abraham SC Nobukawa B Giardiello FM Hamilton SR Wu TT 《The American journal of pathology》2000,157(3):747-754
Fundic gland polyps (FGPs) are the most common gastric polyps in patients with familial adenomatous polyposis (FAP). FGPs have traditionally been regarded as nonneoplastic, possibly hamartomatous lesions, but the pathogenesis of FGPs in both FAP and sporadic patients remains unclear. FGPs in FAP can show foveolar dysplasia, and rarely invasive gastric adenocarcinoma has been reported in patients with FAP and fundic gland polyposis. Using direct gene sequencing and allelic loss assays at 5q, we analyzed somatic adenomatous polyposis coli (APC) gene alterations in 41 FAP-associated FGPs (20 with foveolar dysplasia, six indefinite for dysplasia, and 15 nondysplastic) and 13 sporadic FGPs. The foveolar epithelium and dilated fundic glands of the polyps were separately microdissected and analyzed in 25 of 41 FAP-associated FGPs and 13 of 13 sporadic FGPs. Somatic APC gene alterations were identified frequently (21 of 41 cases, 51%) in FAP-associated FGPs. Both the foveolar epithelium and the dilated fundic gland epithelium comprising the FGPs were shown to carry the same somatic APC gene alteration in 24 (96%) of 25 cases. Furthermore, there was no difference in the frequency of somatic APC gene alterations between FGPs with foveolar dysplasia (10 of 20, 50%), indefinite for dysplasia (four of six, 67%), and nondysplastic (seven of 15, 47%) in FAP patients (P: = 0.697). In contrast, FGPs from non-FAP patients showed infrequent (one of 13, 8%) APC gene alterations (P: = 0.008). These results show that FGPs in FAP patients are pathogenetically distinct from sporadic FGPs. Somatic, second-hit APC gene alterations, which precede morphological dysplasia in many FAP-associated FGPs, indicate that FGPs arising in the setting of FAP are neoplastic lesions. 相似文献