全文获取类型
收费全文 | 1230篇 |
免费 | 171篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 23篇 |
妇产科学 | 18篇 |
基础医学 | 263篇 |
口腔科学 | 47篇 |
临床医学 | 97篇 |
内科学 | 279篇 |
皮肤病学 | 23篇 |
神经病学 | 82篇 |
特种医学 | 118篇 |
外科学 | 146篇 |
综合类 | 39篇 |
预防医学 | 63篇 |
眼科学 | 9篇 |
药学 | 74篇 |
中国医学 | 5篇 |
肿瘤学 | 129篇 |
出版年
2021年 | 9篇 |
2020年 | 11篇 |
2018年 | 25篇 |
2017年 | 17篇 |
2016年 | 24篇 |
2015年 | 28篇 |
2014年 | 23篇 |
2013年 | 35篇 |
2012年 | 42篇 |
2011年 | 52篇 |
2010年 | 42篇 |
2009年 | 50篇 |
2008年 | 42篇 |
2007年 | 55篇 |
2006年 | 43篇 |
2005年 | 36篇 |
2004年 | 43篇 |
2003年 | 25篇 |
2002年 | 35篇 |
2001年 | 31篇 |
2000年 | 33篇 |
1999年 | 23篇 |
1998年 | 31篇 |
1997年 | 51篇 |
1996年 | 45篇 |
1995年 | 29篇 |
1994年 | 30篇 |
1993年 | 32篇 |
1992年 | 27篇 |
1991年 | 28篇 |
1990年 | 28篇 |
1989年 | 35篇 |
1988年 | 37篇 |
1987年 | 28篇 |
1986年 | 27篇 |
1985年 | 26篇 |
1984年 | 18篇 |
1983年 | 20篇 |
1982年 | 11篇 |
1981年 | 25篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 19篇 |
1977年 | 12篇 |
1976年 | 10篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1972年 | 13篇 |
1971年 | 9篇 |
1969年 | 12篇 |
排序方式: 共有1419条查询结果,搜索用时 15 毫秒
51.
To clarify the defective erythropoiesis in eight patients with Diamond- Blackfan anemia, we studied their bone marrow response in vitro to recombinant human interleukin-3 (IL-3) and recombinant granulocyte- macrophage colony-stimulating factor (GM-CSF). In an erythropoietin- containing assay system, specimens from six of the eight patients yielded low numbers of erythroid colonies compared to control values, and in five of these no erythropoietin dose-response could be elicited. Addition of IL-3, GM-CSF or both to cultures from the six patients had no effect on CFU-E-derived colonies. In contrast, IL-3 but not GM-CSF induced a marked increase in the number (183%) and size of the BFU-E- derived colonies in five of the six cases and partially corrected the impaired dose-response to erythropoietin in four. Bone marrow from the other two patients yielded numbers of CFU-E and BFU-E colonies comparable to controls and manifested similar increments in colonies with increasing concentrations of erythropoietin. When IL-3 was added to these cultures, further increments were observed in the number and size of BFU-E colonies. We conclude that IL-3 enhanced the marrow erythropoiesis in most of the patients and exerted a corrective effect on the aberrant colony formation in the presence of erythropoietin. The data raise the possibility of IL-3 as a therapeutic agent in Diamond- Blackfan anemia. 相似文献
52.
Structural studies on the authentic mumps virus nucleocapsid showing uncoiling by the phosphoprotein
53.
54.
55.
Luiz Fernando Gorup Bruno Perlatti Aleksey Kuznetsov Pedro Augusto de Paula Nascente Edison Perevalo Wendler Alcindo A. Dos Santos Willyam Rger Padilha Barros Thiago Sequinel Isabela de Macedo Tomitao Andressa Mayumi Kubo Elson Longo Emerson Rodrigues Camargo 《RSC advances》2020,10(11):6259
Metals capped with organochalcogenides have attracted considerable interest due to their practical applications, which include catalysis, sensing, and biosensing, due to their optical, magnetic, electrochemical, adhesive, lubrication, and antibacterial properties. There are numerous reports of metals capped with organothiol molecules; however, there are few studies on metals capped with organoselenium or organotellurium. Thus, there is a gap to be filled regarding the properties of organochalcogenide systems which can be improved by replacing sulfur with selenium or tellurium. In the last decade, there has been significant development in the synthesis of selenium and tellurium compounds; however, it is difficult to find commercial applications of these compounds because there are few studies showing the feasibility of their synthesis and their advantages compared to organothiol compounds. Stability against oxidation by molecular oxygen under ambient conditions is one of the properties which can be improved by choosing the correct organochalcogenide; this can confer important advantages for many more suitable applications. This paper reports the successful synthesis and characterization of gold nanoparticles functionalized with organochalcogenide molecules (dibutyl-disulfide, dibutyl-diselenide and dibutyl-ditelluride) and evaluates the oxidation stability of the organochalcogenides. Spherical gold nanoparticles with diameters of 24 nm were capped with organochalcogenides and were investigated using X-ray photoelectron spectroscopy (XPS) to show the improved stability of organoselenium compared with organothiol and organotellurium. The results suggest that the organoselenium is a promising candidate to replace organothiol because of its enhanced stability towards oxidation by molecular oxygen under ambient conditions and its slow oxidation rate. The observed difference in the oxidation processes, as discussed, is also in agreement with theoretical calculations.This study presents the improved stability against oxidation by molecular oxygen under ambient conditions of organoselenium compared with organothiol, and organotellurium. 相似文献
56.
Joo Paulo de Campos da Costa Marcelo Assis Vinícius Teodoro Andre Rodrigues Camila Cristina de Foggi Miguel Angel San-Miguel Joo Paulo Pereira do Carmo Juan Andrs Elson Longo 《RSC advances》2020,10(37):21745
This study demonstrates that the electron beam irradiation of materials, typically used in characterization measurements, could be employed for advanced fabrication, modification, and functionalization of composites. We developed irradiation equipment using an electron beam irradiation source to be applied in materials modification. Using this equipment, the formation of a thick Ag film on the Ag3PO4 semiconductor is carried out by electron beam irradiation for the first time. This is confirmed by various experimental techniques (X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy) and ab initio molecular dynamics simulations. Our calculations demonstrate that, at the earlier stages, metallic Ag growth is initiated preferentially at the (110) surface, with the reduction of surface Ag cations forming metallic Ag clusters. As the (100) and (111) surfaces have smaller numbers of exposed Ag cations, the reductions on these surfaces are slower and are accompanied by the formation of O2 molecules.This study demonstrates that the electron beam irradiation of materials, typically used in characterization measurements, could be employed for advanced fabrication, modification, and functionalization of composites. 相似文献
57.
Tommaso Zurleni Elson Gjoni Andrea Ballabio Roberto Casieri Paola Ceriani Luca Marzoli Francesco Zurleni 《World journal of gastrointestinal surgery》2013,5(11):287-293
AIM: To investigate the clinical relevance and prognosis regarding survival according to the changes of the tumor-node-metastasis (TNM) in gastric cancer patients.METHODS: We retrospectively studied 347 consecutive subjects who underwent surgery for gastric adenocarcinoma at the Division of General Surgery, Hospital of Busto Arsizio, Busto Arsizio, Italy between June 1998 and December 2009. Patients who underwent surgery without curative intent, patients with tumors of the gastric stump and patients with tumors involving the esophagus were excluded for survival analysis. Patients were staged according to the 6th and 7th edition TNM criteria; 5-year overall survival rates were investigated, and the event was defined as death from any cause.RESULTS: After exclusion, our study population included 241 resected patients with curative intent for gastric adenocarcinoma. The 5-year overall survival (5-year OS) rate of all the patients was 52.8%. The diagnosed stage differed in 32% of 241 patients based on the TNM edition used for the diagnosis. The patients in stage II according to the 6th edition who were reclassified as stage III had significantly worse prognosis than patients classified as stage II (5-year OS, 39% vs 71%). According to the 6th edition, 135 patients were classifed as T2, and 75% of these patients migrated to T3 and exhibited a significantly worse prognosis than those who remained T2, regardless of lymph node involvement (37% vs 71%). The new N1 patients exhibited a better prognosis than the previous N1 patients (67% vs 43%).CONCLUSION: 7th TNM allows new T2 and N1 patients to be selected with better prognosis, which leads to different staging. New stratification is important in multimodal therapy. 相似文献
58.
Chinnery PF Mowbray C Patel SK Elson JL Sampson M Hitman GA McCarthy MI Hattersley AT Walker M 《Journal of medical genetics》2007,44(6):e80
Mitochondria play a central role in the secretion of insulin by pancreatic beta-cells, and pathogenic mutations of mitochondrial DNA (mtDNA) can cause diabetes. The aetiology of type 2 diabetes has a strong genetic component, raising the possibility that genetic variants of mtDNA alter the risk of developing the disorder. Recent studies have produced conflicting results. By studying 897 UK cases of type 2 diabetes and 1010 population-matched controls, it is shown that European mtDNA haplogroups are unlikely to play a major role in the risk of developing the disorder. 相似文献
59.
60.
Simon S. Jameson James M. Mason Paul N. Baker David W. Elson David J. Deehan Mike R. Reed 《The Journal of arthroplasty》2014
Influence of BMI upon patient outcomes and complications following THA was examined across a national cohort of patients. Outcomes were compared by BMI groups (19.0–29.9 kg/m2 [reference], 30.0–34.9 kg/m2 [obese class I], 35.0 kg/m2+ [obese class II/III]), adjusted for case-mix differences. Obese class I patients had a significantly smaller improvement in OHS (18.9 versus 20.5, P < 0.001) and a greater risk of wound complications (odds ratio [OR] = 1.57, P = 0.006). For obese class II/III patients, there were significantly smaller improvements in OHS and EQ-5D index (P < 0.001), and greater risk of wound complications (P = 0.006), readmission (P = 0.001) and reoperation (P = 0.003). Large improvements in patient outcomes were seen irrespective of BMI, although improvements were marginally smaller and complication rates higher in obese patients. 相似文献