全文获取类型
收费全文 | 2014篇 |
免费 | 191篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 69篇 |
妇产科学 | 42篇 |
基础医学 | 203篇 |
口腔科学 | 33篇 |
临床医学 | 300篇 |
内科学 | 420篇 |
皮肤病学 | 56篇 |
神经病学 | 91篇 |
特种医学 | 188篇 |
外国民族医学 | 1篇 |
外科学 | 250篇 |
综合类 | 24篇 |
预防医学 | 208篇 |
眼科学 | 14篇 |
药学 | 147篇 |
中国医学 | 20篇 |
肿瘤学 | 134篇 |
出版年
2023年 | 35篇 |
2022年 | 90篇 |
2021年 | 129篇 |
2020年 | 80篇 |
2019年 | 68篇 |
2018年 | 64篇 |
2017年 | 59篇 |
2016年 | 63篇 |
2015年 | 72篇 |
2014年 | 99篇 |
2013年 | 98篇 |
2012年 | 119篇 |
2011年 | 109篇 |
2010年 | 88篇 |
2009年 | 98篇 |
2008年 | 84篇 |
2007年 | 68篇 |
2006年 | 101篇 |
2005年 | 72篇 |
2004年 | 57篇 |
2003年 | 57篇 |
2002年 | 45篇 |
2001年 | 12篇 |
2000年 | 15篇 |
1999年 | 27篇 |
1998年 | 38篇 |
1997年 | 44篇 |
1996年 | 42篇 |
1995年 | 29篇 |
1994年 | 26篇 |
1993年 | 30篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 12篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1977年 | 4篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 3篇 |
排序方式: 共有2214条查询结果,搜索用时 15 毫秒
51.
Dung T. Nguyen Lan T. Pham Ha T. T. Le Minh X. Vu Hanh T.
M. Le Huong T. M. Le Nam H. Pham Le T. Lu 《RSC advances》2018,8(35):19707
Magnetic nanoparticles have received much interest for their application in wastewater treatment because of their easy retrieval and reuse. However, the methods used to synthesise high saturation magnetization magnetic nanoparticles require expensive and pure precursors. In the current study, we explore the potential for using spent pickling liquor, a wastewater solution from steel factories, as the iron precursor for preparing iron oxide nanoparticles. Here, magnetic Fe3O4 nanoparticles were synthesized via the oxidation–precipitation of spent pickling liquors using a saturated solution of calcium hydroxide at room temperature. The Fe3O4 nanoparticles were then modified with antibacterial polyguanidine to form a nanocomposite. It was found that monodisperse magnetic Fe3O4 nanoparticles with a size in the range 20–30 nm and a high saturation magnetization value of 73.9 emu g−1 were synthesised. The Fe3O4 nanoparticles were successfully encapsulated with polyguanidine to form an Fe3O4/polyguanidine nanocomposite. FT-IR and TGA analysis results indicated the presence of the polymer on the Fe3O4 surface and the polymer content in the nanocomposite was about 15% (w/w). The Fe3O4/polyguanidine nanocomposite exhibited strong antibacterial activity against Escherichia coli (E. coli), demonstrating its potential for use in disinfecting wastewater.An Fe3O4/polyguanidine nanocomposite with strong antibacterial activity was prepared from Fe3O4 nanoparticles, using spent pickling liquors as the iron source, which were then encapsulated with polyguanidine. 相似文献
52.
Dr. Michael D. Schuffler MD Lawrence R. Kaplan MD Linda Johnson BS MT ASCP 《Digestive diseases and sciences》1978,23(9):821-828
The purpose of this investigation was to determine the frequency and severity of small intestinal mucosal damage in pseudoobstruction syndromes. One hundred eighty-nine interpretable biopsies from 12 patients were blindly reviewed by two investigatiors. The underlying disorders were scleroderma in 7 and idiopathic intestinal pseudoobstruction in 5. All 12 had small-intestinal dilatation on small-bowel series. Eight of the 12 patients had biopsies characterized by moderate, to severe mucosal damage; 3 of these had some biopsies which were flat. The damage did not correlate with: (1) types and numbers of organisms recovered from small intestinal aspirates; (2) duration of illness; (3) degree of dilatation of the proximal small bowel; (4) concentrations of deconjugated bile salts in small intestinal fluid; or (5) amount of fat absorbed in fat-balance studies. We conclude that mucosal damage is common in pseudoobstruction syndromes. The pathogenesis of the damage and its relationship to intraluminal bacteria remain undefined. 相似文献
53.
The finding of elevated intracellular levels of adenosine deaminase (ADA) in some patients with acute lymphoblastic leukemia has led to attempts to control this disease with the adenosine deaminase inhibitor 2'-deoxycoformycin (dCF). Because of clinical reports indicating its relative freedom from myelotoxicity, we have tested the effects of this drug on erythroid, granulocytic, and T-lymphocyte colony formation by normal marrow and peripheral blood cells. While clinically the drug has been found to be active at serum concentrations of approximately 10 microM, we have tested it at concentrations up to and including 1 mM. It was found that both erythroid and granulocytic colony growth was completely unaffected by 1 mM dCF, a concentration at least 2 magnitudes higher than that necessary to totally ablate intracellular ADA levels. T-lymphocyte colony growth was unaffected by 100 microM dCF, but at 1 mM some inhibition was observed. These findings therefore indicate that dCF, while able to cause leukemic cell lysis in vivo, has no inhibitory effect on the proliferative capacity of normal hematopoietic cells. 相似文献
54.
55.
Christine E. Wong Jennifer S. Yu David A. Quigley Minh D. To Kuang-Yu Jen Phillips Y. Huang Reyno Del Rosario Allan Balmain 《Genes & development》2013,27(6):670-682
Epithelial–mesenchymal transition (EMT) is thought to be an important, possibly essential, component of the process of tumor dissemination and metastasis. About 20%–30% of Hras mutant mouse skin carcinomas induced by chemical initiation/promotion protocols have undergone EMT. Reduced exposure to TPA-induced chronic inflammation causes a dramatic reduction in classical papillomas and squamous cell carcinomas (SCCs), but the mice still develop highly invasive carcinomas with EMT properties, reduced levels of Hras and Egfr signaling, and frequent Ink4/Arf deletions. Deletion of Hras from the mouse germline also leads to a strong reduction in squamous tumor development, but tumors now acquire activating Kras mutations and exhibit more aggressive metastatic properties. We propose that invasive carcinomas can arise by different genetic and biological routes dependent on exposure to chronic inflammation and possibly from different target cell populations within the skin. Our data have implications for the use of inhibitors of inflammation or of Ras/Egfr pathway signaling for prevention or treatment of invasive cancers. 相似文献
56.
57.
58.
Nakasone N Tran HH Nguyen MB Higa N Toma C Song T Ichinose Y Iwanaga M 《The American journal of tropical medicine and hygiene》2005,73(3):586-587
Enterohemorrhagic Escherichia coli O157:H7 was isolated for the first time in Vietnam. Shiga toxin-producing E. coli were isolated from 8 of 100 cows examined. The two strains showing serotype O157:H7 carried the eae, ehxA, and stx2c genes, but the other six were negative for the eae gene. 相似文献
59.
Marco A Costa Steven Shoemaker Hideki Futamatsu Chris Klassen Dominick J Angiolillo Minh Nguyen Alan Siuciak Paul Gilmore Martin M Zenni Luis Guzman Theodore A Bass Norbert Wilke 《Journal of the American College of Cardiology》2007,50(6):514-522
OBJECTIVES: To evaluate the ability of quantitative perfusion cardiac magnetic resonance (CMR) to assess the hemodynamic significance of coronary artery disease (CAD) compared with well-established anatomic and physiologic techniques. BACKGROUND: Fractional flow reserve (FFR) is considered by many investigators to be a reliable stenosis-specific method to determine hemodynamically significant CAD. Quantitative perfusion CMR is a promising noninvasive approach to detect CAD but has yet to be validated against FFR. METHODS: This is a prospective study in patients with suspected CAD who underwent coronary angiography, FFR, and CMR assessments. The quantitative myocardial perfusion reserve (MPR) was calculated in 720 myocardial sectors (8 sectors/slice). The MPR was calculated from the ratio between stress and rest myocardial flow based on signal intensity time curves using deconvolution analysis. Stress was simulated with adenosine for both FFR and MPR. The MPR assessments were compared to FFR (n = 44 coronary segments) and quantitative coronary angiography (n = 108 segments) in the corresponding coronary territories. RESULTS: The MPR was 1.54 +/- 0.36 in segments with FFR < or =0.75 (n = 14) and 2.11 +/- 0.68 in those with FFR >0.75 (n = 30; p = 0.0054). An MPR cutoff of 2.04 was 92.9% (95% CI 77.9 to 100.0) sensitive and 56.7% (95% CI 32.8 to 80.6) specific in predicting a coronary segment with FFR < or =0.75. The MPR was 1.54 +/- 0.49 in coronary segments with > or =50% diameter stenosis (DS) (n = 47) and 2.13 +/- 0.80 in segments with <50% DS (n = 61; p < 0.001). An MPR cutoff of 2.04 was 85.1% (95% CI 71.1 to 99.2) sensitive and 49.2% (95% CI 33.6 to 64.8) specific in predicting CAD with > or =50% DS. CONCLUSIONS: Quantitative perfusion CMR is a safe noninvasive test that represents a stenosis-specific alternative to determine the hemodynamic significance of CAD. 相似文献
60.