全文获取类型
收费全文 | 1791篇 |
免费 | 218篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 63篇 |
妇产科学 | 17篇 |
基础医学 | 240篇 |
口腔科学 | 30篇 |
临床医学 | 193篇 |
内科学 | 412篇 |
皮肤病学 | 19篇 |
神经病学 | 106篇 |
特种医学 | 95篇 |
外科学 | 235篇 |
综合类 | 29篇 |
一般理论 | 5篇 |
预防医学 | 294篇 |
眼科学 | 103篇 |
药学 | 55篇 |
中国医学 | 2篇 |
肿瘤学 | 129篇 |
出版年
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 25篇 |
2020年 | 29篇 |
2019年 | 34篇 |
2018年 | 31篇 |
2017年 | 43篇 |
2016年 | 27篇 |
2015年 | 33篇 |
2014年 | 38篇 |
2013年 | 69篇 |
2012年 | 77篇 |
2011年 | 94篇 |
2010年 | 66篇 |
2009年 | 40篇 |
2008年 | 87篇 |
2007年 | 93篇 |
2006年 | 82篇 |
2005年 | 68篇 |
2004年 | 68篇 |
2003年 | 77篇 |
2002年 | 86篇 |
2001年 | 74篇 |
2000年 | 65篇 |
1999年 | 54篇 |
1998年 | 38篇 |
1997年 | 39篇 |
1996年 | 33篇 |
1995年 | 31篇 |
1994年 | 29篇 |
1993年 | 26篇 |
1992年 | 35篇 |
1991年 | 28篇 |
1990年 | 46篇 |
1989年 | 37篇 |
1988年 | 41篇 |
1987年 | 42篇 |
1986年 | 33篇 |
1985年 | 29篇 |
1984年 | 14篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1975年 | 13篇 |
1974年 | 12篇 |
1973年 | 5篇 |
1968年 | 5篇 |
排序方式: 共有2028条查询结果,搜索用时 31 毫秒
61.
Wakefield JC 《The Journal of nervous and mental disease》2012,200(6):499-511
The proposed changes to DSM-5 will create new categories of mental disorder (referred to here generically as Prolonged Grief Disorder' [PGD]) to diagnose individuals experiencing prolonged intense grief reactions to the loss of a loved one. Individuals could be diagnosed even if they have no depressive or anxiety symptoms but only symptoms typical of grief (e.g., yearning, avoidance of reminders, disbelief, feelings of emptiness). The main challenge for such proposals is to establish that the proposed diagnostic criteria validly discriminate a genuine psychiatric disorder of grief from intense normal grief. With this test in mind, I evaluate the soundness of four empirical arguments and one conceptual argument that have been put forward to support such proposals: (1) PGD has discriminant validity because distinctive, pathognomonic symptoms distinguish it from normal grief; (2) PGD has discriminant validity because it identifies grief symptoms that are of greater absolute severity than in normal grief; (3) PGD has predictive validity because it implies a chronic, interminable process of grieving, thus a derailment of the normal process of grief resolution; (4) PGD has predictive validity because it predicts negative mental and physical health outcomes unlikely in normal grief; and (5) PGD has conceptual validity because grief is analogous to a wound or, alternatively, lengthy grief is analogous to a wound that does not heal. Upon close examination, each of these arguments turns out to have serious empirical or conceptual deficiencies. I conclude that the proposed diagnostic criteria for PGD fail to discriminate disorder from intense normal grief and are likely to yield massive false-positive diagnoses. Consequently, the proposal to add pathological grief categories to DSM-5 should be withdrawn pending further research to identify more valid criteria for diagnosing PGD. 相似文献
62.
Use of the appropriateness evaluation protocol for estimating the incremental costs associated with nosocomial infections 总被引:1,自引:0,他引:1
Existing methods for estimating additional days of hospital stay due to nosocomial infections (NI) have a number of documented limitations. An alternative method described in this paper uses the Appropriateness Evaluation Protocol (AEP) to determine whether each day of acute inpatient care is appropriate based on the need for care of the NI, original cause of hospitalization (OC), or combined NI-OC requirements. Using this method to identify specific days of hospitalization due to Staphylococcus aureus nosocomial infection, we find: 1) length of stay is increased for only a minority of patients (38%); 2) an average of 20 additional days of stay occurred for patients with 1 or more days attributed to NI; and 3) an average of 52% of length of stay of patients with 1 or more days attributed to NI can be attributed to the NI. Application of the AEP-based method is a useful alternative for identifying additional days of stay due to NI. 相似文献
63.
Macrovascular thrombosis is driven by tissue factor derived primarily from the blood vessel wall 总被引:21,自引:3,他引:21
Day SM Reeve JL Pedersen B Farris DM Myers DD Im M Wakefield TW Mackman N Fay WP 《Blood》2005,105(1):192-198
Leukocytes and leukocyte-derived microparticles contain low levels of tissue factor (TF) and incorporate into forming thrombi. Although this circulating pool of TF has been proposed to play a key role in thrombosis, its functional significance relative to that of vascular wall TF is poorly defined. We tested the hypothesis that leukocyte-derived TF contributes to thrombus formation in vivo. Compared to wild-type mice, mice with severe TF deficiency (ie, TF(-/-), hTF-Tg+, or "low-TF") demonstrated markedly impaired thrombus formation after carotid artery injury or inferior vena cava ligation. A bone marrow transplantation strategy was used to modulate levels of leukocyte-derived TF. Transplantation of low-TF marrow into wild-type mice did not suppress arterial or venous thrombus formation. Similarly, transplantation of wild-type marrow into low-TF mice did not accelerate thrombosis. In vitro analyses revealed that TF activity in the blood was very low and was markedly exceeded by that present in the vessel wall. Therefore, our results suggest that thrombus formation in the arterial and venous macrovasculature is driven primarily by TF derived from the blood vessel wall as opposed to leukocytes. 相似文献
64.
65.
Five female patients and one male patient with solid and papillary epithelial neoplasms of the pancreas were examined with computed tomography (CT). The mean age of the patients was 27 years (range, 13-46 years). All cases showed well-encapsulated, round or lobulated masses consisting of both cystic and solid areas. Cystic portions showed CT numbers that suggested hemorrhagic necrosis. There were no internal septations within the masses. In three tumors located in the head of the pancreas, dilatation of the biliary tree was absent or minimal, although the masses were large. Two tumors contained calcifications. One tumor demonstrated metastatic deposits in liver and lymph nodes. Metastatic masses appeared similar to the primary pancreatic mass. Solid and papillary neoplasm of the pancreas should be the primary diagnostic consideration when characteristic CT findings are detected in a young female patient. 相似文献
66.
Hodgkin disease: CT of the thymus 总被引:2,自引:0,他引:2
The computed tomography (CT) scans in two groups of patients with Hodgkin disease were reviewed to determine the frequency of thymic enlargement. In 50 CT scans from 50 patients with evidence of thoracic disease on CT scans who were examined for primary staging, the thymus was enlarged in 15 of 50 (30%). Fifty CT scans were obtained from 44 patients at the time of 50 separate episodes of known or suspected relapse. Relapse occurred in the mediastinum in 12 episodes, lung parenchyma in five, and both sites in one. Thymic enlargement thought to be due to involvement by disease was present in seven of 18 (38%). Mediastinal disease was associated with thymic enlargement in all but one patient in whom a thymic cyst developed after radiation therapy. Differentiation of thymic enlargement from enlarged superior mediastinal lymph nodes was easily made in all but two patients. Thymic enlargement in the absence of lymph node enlargement may indicate a different disease, since isolated Hodgkin disease of the thymus is uncommon. Primary thymic tumor should be considered initially, whereas after treatment, rebound hyperplasia of the thymus may be the cause of enlargement. 相似文献
67.
A polymer system was developed for use in permanent inflation of detachable balloons, to avoid long-term reliance on the integrity of balloon shells or valve mechanisms. This system is based on 2-hydroxy-ethyl methacrylate (HEMA) as the monomer, in combination with a cross-linking agent and a water-soluble curing system. The low-viscosity, hydrophilic mixture can be exchanged through a small-bore catheter into a detachable balloon and polymerizes in 40-60 minutes at body temperature. Partially polymerized HEMA can cause vascular occlusion; hence, careful timing of balloon detachment is required. The evolution of the radiographic appearance of HEMA-filled balloons is predictable. The balloons remain radiopaque on plain radiographs as long as the balloon shell and valve mechanisms are competent. After rupture of the shell or failure of the valve mechanism, the balloons become invisible on plain radiographs but remain hyperattenuating on computed tomography scans. 相似文献
68.
雄激素对骨骼肌合成有明显影响,随着年龄增大,雄激素的下降常伴随肌量和肌力的下降。这种肌量和肌功能的下降,被称为少肌症或肌体老化,是老年人体质弱化(男性化减退)进展的关键事项。也是导致快速机能衰退及其不良后果的关键。雄激素水平下降对老年男性体质弱化(男性化减退)的潜在影响和对躯体功能的促进治疗作用无疑已经引起了相当的关注。本综述概述了近期关于肌肉老化、少肌症、老年体质弱化的概念、定义,并评估了关于雄激素和老年体质弱化的研究进展。近期源于观测性和介入性研究的证据强烈支持雄激素对老年男性肌量的作用,但雄激素对肌力和特有的躯体功能的效用并不明确。研究显示,雄激素治疗在老年男性中通常有良好的耐受性,而近期的研究则关注于雄激素的高剂量治疗和对于心血管风险较高人群的治疗。雄激素受体调节剂(SARMs)的初期试验研究显示传统雄激素治疗对于老年患者在肌量和肌功能方面有相同的效用。将来的重要研究方向包括利用这类雄激素治疗并结合适用于不同老年患者群体促进躯体功能的运动训练,同时将更多地关注近期关于激素水平、身体成分及躯体功能间关系的观测性(回顾性)研究。 相似文献
69.
Maggie KM Ma Helen KW Law Kin Sun Tse Kwok Wah Chan Gary CW Chan Desmond YH Yap Maggie MY Mok Lorraine PY Kwan Sydney CW Tang Bo Ying Choy Tak Mao Chan 《International journal of urology》2018,25(5):450-455
Objectives
To evaluate the use of shear wave elastography in assessment of kidney allograft tubulointerstitial fibrosis.Methods
Shear wave elastography assessment was carried out by two independent operators in kidney transplant recipients who underwent allograft biopsy for clinical indications (i.e. rising creatinine >15% or proteinuria >1 g/day). Allograft biopsies were interpreted by the same pathologist according to the 2013 Banff Classification.Results
A total of 40 elastography scans were carried out (median creatinine 172.5 μmol/L [interquartile range 133.8–281.8 μmol/L]). Median tissue stiffness at the cortex (22.6 kPa [interquartile range 18.8–25.7 kPa] vs 22.3 kPa [interquartile range 19.0–26.5 kPa], P = 0.70) and medulla (15.0 kPa [interquartile range 13.7–18.0 kPa] vs 15.6 kPa [interquartile range 14.4–18.2 kPa]) showed no significant differences between the two observers. Interobserver agreement was satisfactory (intraclass correlation coefficient of the cortex 0.84, 95% CI 0.70–0.92 and intraclass correlation coefficient of the medulla 0.88, 95% CI 0.78–0.94). The areas under the receiver operating characteristic curves for detection of tubulointerstitial fibrosis were estimated to be 0.75 (95% CI 0.61–0.89), 0.85 (95% CI 0.75–0.95) and 0.65 (95% CI 0.53–0.78) for cortical, medullary tissue stiffness and serum creatinine, respectively.Conclusions
Shear wave elastography can be used as a non‐invasive tool to evaluate kidney allograft fibrosis with reasonable interobserver agreement and superior test performance to serum creatinine in detecting early tubulointerstitial fibrosis. 相似文献70.
Chemoattractant-induced changes in surface expression and redistribution of a functional ligand for P-selectin on neutrophils 总被引:4,自引:0,他引:4
Adhesion between platelets and neutrophils is mediated through the interaction of P-selectin on activated platelets with a carbohydrate- containing structure on neutrophils, and occurs under both static and shear conditions. Recent studies using flow chambers have shown that neutrophils become activated after binding to surface-adherent platelets expressing P-selectin. The objective of the present study was to investigate the effect of such activation on the interactions of platelet P-selectin with its ligand on neutrophils. Flow cytometric analyses using P-selectin chimeras revealed that activation induced a rapid and marked reduction in chimera binding, with levels of binding decreased by 71% after 15 minutes of stimulation with the chemotactic agent, FMLP. Using a visual assay of platelet-neutrophil rosetting, we showed that the P-selectin ligand was translocated and clustered at the uropod of neutrophils following the shape changes and polarization induced by chemotactic stimulation. Activated neutrophils bound to surface-adherent platelets also displayed the clustering of P-selectin ligand at the uropod, and these neutrophils detached from the platelets when a shear stress (2 dynes/cm2) was applied through the adhesion chamber. These results indicate that chemotactic stimulation of neutrophils induces changes in the surface expression and distribution of a biologically relevant ligand for P-selectin, and that these changes might influence the adhesive interactions occurring between neutrophils and activated platelets. 相似文献