全文获取类型
收费全文 | 633篇 |
免费 | 37篇 |
国内免费 | 34篇 |
专业分类
儿科学 | 40篇 |
妇产科学 | 6篇 |
基础医学 | 75篇 |
口腔科学 | 24篇 |
临床医学 | 102篇 |
内科学 | 144篇 |
皮肤病学 | 15篇 |
神经病学 | 9篇 |
特种医学 | 115篇 |
外科学 | 38篇 |
综合类 | 15篇 |
预防医学 | 28篇 |
眼科学 | 2篇 |
药学 | 64篇 |
肿瘤学 | 27篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 11篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 23篇 |
2013年 | 31篇 |
2012年 | 17篇 |
2011年 | 13篇 |
2010年 | 26篇 |
2009年 | 37篇 |
2008年 | 13篇 |
2007年 | 30篇 |
2006年 | 20篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 14篇 |
2001年 | 6篇 |
2000年 | 11篇 |
1999年 | 21篇 |
1998年 | 34篇 |
1997年 | 34篇 |
1996年 | 36篇 |
1995年 | 24篇 |
1994年 | 34篇 |
1993年 | 21篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 20篇 |
1988年 | 24篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1969年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有704条查询结果,搜索用时 62 毫秒
11.
报道了β-阻滞剂塞利洛尔的简便制备方法,即以对乙氧基苯胺为原料,经酰胺化,傅克反应,以环氧氯丙烷取代,最后用叔丁胺直接与环氧基反应开环等4步反应制得。比文献五步反应缩短了一步,产物经元素分析、红外光谱、核磁共振谱、质谱等分析确定结构。 相似文献
12.
13.
Hausegger KA; Cragg AH; Lammer J; Lafer M; Fluckiger F; Klein GE; Sternthal MH; Pilger E 《Radiology》1994,190(1):199
14.
X-linked chronic granulomatous disease: correction of NADPH oxidase defect by retrovirus-mediated expression of gp91-phox 总被引:3,自引:0,他引:3
Chronic granulomatous disease (CGD) is an inherited immunodeficiency resulting from the inability of an individual's phagocytes to produce superoxide anions because of defective NADPH oxidase. The disease may be treated by bone marrow transplantation and as such is a candidate for somatic gene therapy. Two thirds of patients have defects in an X- linked gene (X-CGD) encoding gp91-phox, the large subunit of the membrane cytochrome b-245 component of NADPH oxidase. Epstein-Barr virus-transformed B-cell lines from patients with CGD provide a model system for the disease. We have used retrovirus-mediated expression of gp91-phox to reconstitute functionally NADPH oxidase activity in B-cell lines from three unrelated patients with X-CGD. The protein is glycosylated and membrane associated, and the reconstituted oxidase is appropriately activated via protein kinase C. The kinetics of superoxide production by such reconstituted cells is similar to that of normal B-cell lines. These data show the potential of gene therapy for this disease. 相似文献
15.
The merits of surgical treatment of fractures of the mandibular condyle versus non-surgical management remains highly controversial, despite a large volume of literature dedicated to this topic. One reason the controversy remains, is because most of the outcomes in the literature are not directly comparable. The disparate range of condylar fracture classifications used is one of the reasons that studies are not comparable. We sought to review classification systems for condylar fractures used in the recent scientific literature.Review of the literature from 2016 to 2019, looking for papers relating to fractures of the mandibular condyle. Papers identified were assessed for type of study, focus of study, classification system used.88 studies were identified, including prospective and retrospective cohort studies, randomised and non-randomised prospective studies, randomised controlled trials and case series. More studies focussed on epidemiological factors than surgical access, fixation or outcomes. 31 used no classification system, whilst 17 used unique classification systems and 40 used previously referenced classification systems.Classification systems are used to help separate clinical problems into distinguishable groups, where there is a difference in management or outcome depending on the distinguishing features.There is currently a wide diversity of classification systems used for condyle fractures, and as a result, comparisons of surgical access, fixation and outcomes are difficult to make. Having a single classification system across the published literature would allow easier comparison and the classification proposed by the AO group is recommended for future use. 相似文献
16.
In two previous studies, we observed that recombinant human interleukin- 3 (IL-3) induced an increase in marrow burst-forming unit-erythroid- derived colonies in vitro in some patients with Diamond-Blackfan anemia (DBA). To determine whether a similar erythropoietic response could be induced in vivo, we treated 13 patients with DBA (aged 4 to 19 years) with two preparations of IL-3. All patients had absent absolute reticulocyte counts and markedly reduced to absent recognizable bone marrow erythroid elements; patients with circulating reticulocytes in the previous 12 months were excluded from study. All patients except 1 had failed steroid therapy and had been transfusion-dependent since infancy; 1 patient was maintained on high-dose prednisone at the time of enrollment. On the first arm of the study, IL-3 (Immunex Corp, Seattle, WA) was administered subcutaneously using a dose escalation regimen of 125 to 500 micrograms/m2/day in divided dosage at 12-hour intervals, coadministered with 1.5 mg/kg/d of oral ferrous sulphate. Of the 13 patients that entered the trial, 4 stopped prematurely because of adverse side effects. In the other 9 evaluable cases, reticulocytes increased transiently in 1 patient from 0 to 65 x 10(9)/L after 35 days of IL-3 therapy at 250 micrograms/m2, but transfusion dependency persisted. One transient peak in absolute reticulocyte count was noted in 6 other patients, but no erythroid response was observed after completion of a full course of IL-3. Oral prednisone at 0.5 mg/kg/d was then coadministered with IL-3 at 500 micrograms/m2 to 5 of the patients without effect, and treatment was stopped. In 2 patients, a second preparation of IL-3 (Sandoz Canada Inc, Dorval, Quebec, Canada) was initiated in a dose escalation regimen of 2.5 to 10 micrograms/kg and was coadministered with ferrous sulphate. No erythroid response was observed in either patient, and in one of the two, alternate-day subcutaneous recombinant erythropoietin at 300 U/kg was administered for 3 weeks in combination with daily IL-3 at 10 micrograms/kg, but no increased erythropoiesis was seen. Significant increases in white blood cell and eosinophil counts during administration of both preparations of IL-3 were observed in all patients. These data show that the response of DBA patients to IL-3 in vivo is heterogeneous and cannot be predicted from in vitro studies. The absence of a corrective effect of IL-3 in these patients with DBA indicates that a deficiency of the cytokine is not central in the pathogenesis of the disorder. 相似文献
17.
Z Khalpey MH Yacoub RT Smolenski 《Annals of the Royal College of Surgeons of England》2013,95(1):9-14
Introduction
Human donor organ shortages have led surgeons and scientists to explore the use of animals as alternative organ sources. Acute thrombovascular rejection (AVR) is the main hurdle in xenotransplantation. Disparities in nucleotide metabolism in the vessels of different species may contribute significantly to the microvascular component of AVR.Methods
We evaluated the extent of nucleotide metabolism mismatch in selected organs and endothelial cells of different mammals with particular focus on the changes in activity of ecto-5’-nucleotidase (E5’N) elicited by exposure of porcine hearts or endothelial cells to human blood (ex vivo) or human plasma (in vitro).Results
E5’N activity in the rat heart was significantly higher than in other species. We noted a significant difference (p<0.001) in E5’N activity between human and pig endothelial cell lines. Initial pig aortic endothelial E5’N activity decreased in vitro after a three-hour exposure to human and porcine plasma while remaining constant in controls. Ex vivo perfusion with fresh human blood for four hours resulted in a significant decrease of E5’N activity in both wild type and transgenic pig hearts overexpressing human decay accelerating factor (p<0.001).Conclusions
This study provides evidence that mismatches in basal mammalian metabolic pathways and humoral immunity interact in a xenogeneic environment. Understanding the role of nucleotide metabolism and signalling in xenotransplantation may identify new targets for genetic modifications and may lead to the development of new therapies extending graft survival. 相似文献18.
DC Bosanquet CN Jones N Gill P Jarvis MH Lewis 《Annals of the Royal College of Surgeons of England》2013,95(1):15-19
Introduction
Numerous strategies are employed routinely in an effort to lower rates of surgical site infections (SSIs). A laminar flow theatre environment is generally used during orthopaedic surgery to reduce rates of SSIs. Its role in vascular surgery, especially when arterial bypass grafts are used, is unknown.Methods
A retrospective review of a prospectively maintained database was undertaken for all vascular procedures performed by a single consultant over a one-year period. Cases were performed, via random allocation, in either a laminar or non-laminar flow theatre environment. Demographic data, operative data and evidence of postoperative SSIs were noted. A separate subgroup analysis was undertaken for patients requiring an arterial bypass graft. Univariate and multivariate logistical regression was undertaken to identify significant factors associated with SSIs.Results
Overall, 170 procedures were analysed. Presence of a groin incision, insertion of an arterial graft and a non-laminar flow theatre were shown to be predictive of SSIs in this cohort. In the subgroup receiving arterial grafts, only a non-laminar flow theatre environment was shown to be predictive of an SSI.Conclusions
This study suggests that laminar flow may reduce incidences of SSI, especially in the subgroup of patients receiving arterial grafts. 相似文献19.
Khaleghi S Rahbarizadeh F Ahmadvand D Rasaee MJ Pognonec P 《International journal of hematology》2012,95(4):434-444
In accordance with the two-step hypothesis of T cell activation and the observation that stimulation through the T cell receptor
(TCR) alone may lead to anergy, we focused on the introduction of co-stimulatory signaling to this type of receptors to achieve
optimal activation. Enhanced mRNA and cell surface receptor expression via the co-stimulatory gene fragment (OX40) was confirmed
by RT-PCR and flow cytometry. Inclusion of the OX40 co-stimulatory signaling region in series with the TCR led to enhanced
antigen-induced IL-2 production after stimulation by MUC1-expressing cancer cell lines as compared to the chimeric receptor
without OX40. Moreover, with the aim of maintaining high efficiency, while providing a means of controlling any possible unwanted
proliferation in vivo, a regulation system was used. This controls the dimerization of a membrane-bound caspase 8 protein.
Toward that goal, pFKC8 and CAR constructs were co-transfected into Jurkat cells, and the level of apoptosis was measured.
24 h after addition of the dimerizer, a 91% decrease in transfected cells was observed. 相似文献
20.