首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1910篇
  免费   105篇
  国内免费   3篇
耳鼻咽喉   38篇
儿科学   193篇
妇产科学   66篇
基础医学   195篇
口腔科学   36篇
临床医学   101篇
内科学   331篇
皮肤病学   21篇
神经病学   183篇
特种医学   35篇
外科学   312篇
综合类   45篇
现状与发展   1篇
一般理论   1篇
预防医学   73篇
眼科学   38篇
药学   156篇
中国医学   6篇
肿瘤学   187篇
  2022年   23篇
  2021年   48篇
  2020年   21篇
  2019年   31篇
  2018年   47篇
  2017年   33篇
  2016年   44篇
  2015年   47篇
  2014年   47篇
  2013年   64篇
  2012年   102篇
  2011年   117篇
  2010年   78篇
  2009年   70篇
  2008年   94篇
  2007年   112篇
  2006年   91篇
  2005年   109篇
  2004年   72篇
  2003年   74篇
  2002年   57篇
  2001年   53篇
  2000年   51篇
  1999年   46篇
  1998年   19篇
  1997年   21篇
  1996年   13篇
  1995年   11篇
  1992年   31篇
  1991年   29篇
  1990年   24篇
  1989年   17篇
  1988年   28篇
  1987年   16篇
  1986年   13篇
  1985年   17篇
  1984年   12篇
  1983年   16篇
  1982年   14篇
  1981年   10篇
  1979年   10篇
  1978年   19篇
  1977年   21篇
  1976年   12篇
  1975年   11篇
  1974年   20篇
  1973年   14篇
  1972年   15篇
  1970年   12篇
  1968年   8篇
排序方式: 共有2018条查询结果,搜索用时 15 毫秒
41.
Somewhat paradoxically, fracture risk, which depends on applied loads and bone strength, is elevated in both anorexia nervosa and obesity at certain skeletal sites. Factor‐of‐risk (Φ), the ratio of applied load to bone strength, is a biomechanically based method to estimate fracture risk; theoretically, higher Φ reflects increased fracture risk. We estimated vertebral strength (linear combination of integral volumetric bone mineral density [Int.vBMD] and cross‐sectional area from quantitative computed tomography [QCT]), vertebral compressive loads, and Φ at L4 in 176 women (65 anorexia nervosa, 45 lean controls, and 66 obese). Using biomechanical models, applied loads were estimated for: 1) standing; 2) arms flexed 90°, holding 5 kg in each hand (holding); 3) 45° trunk flexion, 5 kg in each hand (lifting); 4) 20° trunk right lateral bend, 10 kg in right hand (bending). We also investigated associations of Int.vBMD and vertebral strength with lean mass (from dual‐energy X‐ray absorptiometry [DXA]) and visceral adipose tissue (VAT, from QCT). Women with anorexia nervosa had lower, whereas obese women had similar, Int.vBMD and estimated vertebral strength compared with controls. Vertebral loads were highest in obesity and lowest in anorexia nervosa for standing, holding, and lifting (p < 0.0001) but were highest in anorexia nervosa for bending (p < 0.02). Obese women had highest Φ for standing and lifting, whereas women with anorexia nervosa had highest Φ for bending (p < 0.0001). Obese and anorexia nervosa subjects had higher Φ for holding than controls (p < 0.03). Int.vBMD and estimated vertebral strength were associated positively with lean mass (R = 0.28 to 0.45, p ≤ 0.0001) in all groups combined and negatively with VAT (R = –[0.36 to 0.38], p < 0.003) within the obese group. Therefore, women with anorexia nervosa had higher estimated vertebral fracture risk (Φ) for holding and bending because of inferior vertebral strength. Despite similar vertebral strength as controls, obese women had higher vertebral fracture risk for standing, holding, and lifting because of higher applied loads from higher body weight. Examining the load‐to‐strength ratio helps explain increased fracture risk in both low‐weight and obese women. © 2015 American Society for Bone and Mineral Research.  相似文献   
42.
43.
In the present study, we have synthesized mixed cuprous/copper oxide nanosuspensions by metallosurfactant based microemulsion technique. Three metallosurfactants were synthesized which includes two non-ionic double chained metallosurfactants with C12, C16 chains with coordinated copper i.e. Cudda and Cuhexa, respectively. Another cationic double chained metallosurfactant with loosely bound metal (Cuctac) was also prepared. The prepared metallocomplexes were characterized using FTIR, elemental analysis, and NMR. The effect of the position of metallosurfactant in microemulsion on the fabrication and properties of nanosuspensions was elucidated. In this method, no external reducing agent and capping agent were added and tween 80 acted both as reducing and stabilizing agent for the nanoparticles. The synthesized nanoparticles were characterized and it was observed that mixed copper and cuprous oxide particles are present in colloidal suspension for all the three studied metallosurfactants. The kinetics of formation of mixed copper/cuprous oxide nanosuspensions (Ns) and their stability was estimated using Uv-visible spectroscopy. Further, the binding and interactions of copper nanosuspensions with calf Thymus DNA (CT-DNA) were assessed using Uv–vis spectroscopy, circular dichroism and gel electrophoresis. Additionally, the antioxidant activity of the Cu Ns was checked using DPPH assay. The role of positive charge on nanoparticles as evaluated from Zeta potential was responsible for DNA affinity. The DNA conformational changes in the presence of nanosuspensions and relevant scavengers were investigated. Further, the anti-proliferative activity of copper Ns was assessed using HeLa cells and Cuhexa derived Ns were proved to be active with highest activity at a low concentration and were nontoxic towards normal cell lines. In summary, this work demonstrates a softer approach for the synthesis of copper nanosuspensions with a size range of 2–5?nm and evaluated the role of type and structure of metallosurfactant on size, stability of particles and anti-proliferative activity.  相似文献   
44.
AIM: The purpose of this article is to report a rare case of primary tuberculosis of the tongue. BACKGROUND: Tuberculosis is an infectious, chronic granulomatous disease that can involve almost any organ in the body, but primary lesions are usually confined to the lungs. Oral lesions are an infrequent occurrence in tuberculosis, and tuberculosis of the oral cavity is often a consequence of active pulmonary tuberculosis. Although primary tuberculosis in the oral cavity has been documented, it is a rare occurrence. REPORT: A 42-year-old male patient presented with chief complaints of severe pain and ulceration on the ventrolateral surface of the left side of the tongue, measuring about 1.25 x 1.50 cm with surrounding erythema and induration of one-month duration. The ulcer was initially painless but became painful later with increased severity over time. The sore tongue caused difficulty in eating, drinking, swallowing, and even talking. The patient also complained of malaise for some duration, but there was no history of fever, cough, weight loss, and his bladder-bowel habits were normal. An excisional biopsy differentiated the lesion from squamous cell carcinoma and confirmed the diagnosis. SUMMARY: Even though primary tuberculosis in the oral cavity is a rare finding, it must be included in the differential diagnosis of mucosal lesions. This case provides a clinical example of the importance of this inclusion for the well being of the patient and for the community due to the communicable nature of the disease.  相似文献   
45.

Gastro-oesophageal reflux disease (GORD) after one anastomosis gastric bypass (OAGB) remains a concern. We reviewed the current literature on revisional surgery after OAGB for GORD. MEDLINE, EMBASE, and PubMed databases were searched. We identified 21 studies, appraising 13,658 OAGB patients. A total of 230 (1.6%) patients underwent revisional surgery for GORD. Revision to Roux-en-Y configuration was performed in 211 (91.7%) patients. Six (2.6%) patients had a Braun entero-enterostomy added to the OAGB. Thirteen (5.6%) patients underwent excluded stomach fundoplication (ESF). Reflux symptoms resolved in 112 (48.6%) patients, persisted in 13 (5.6%) patients, and were not reported in 105 (45.6%) patients. Revisional surgery after OAGB for GORD appears to be rare, and when required, conversion to Roux-en-Y configuration is the commonest choice.

  相似文献   
46.
The A7 harmonization team (A7 HT), a part of the Global Bioanalysis Consortium (GBC), focused on reviewing best practices for repeat analysis and incurred sample reanalysis (ISR) as applied during regulated bioanalysis. With international representation from Europe, Latin America, North America, and the Asia Pacific region, the team first collated common practices and guidance recommendations and assessed their suitability from both a scientific and logistical perspective. Subsequently, team members developed best practice recommendations and refined them through discussions and presentations with industry experts at scientific meetings. This review summarizes the team findings and best practice recommendations. The few topics where no consensus could be reached are also discussed. The A7 HT recommendations, together with those from the other GBC teams, provide the basis for future international harmonization of regulated bioanalytical practices.  相似文献   
47.
48.
49.
Neurocritical Care - In the original article, Figure&nbsp;5 has incorrect EEG images and the corrected version is shown below.  相似文献   
50.
Pericyte-mediated capillary constriction decreases cerebral blood flow in stroke after an occluded artery is unblocked. The determinants of pericyte tone are poorly understood. We show that a small rise in cytoplasmic Ca2+ concentration ([Ca2+]i) in pericytes activated chloride efflux through the Ca2+-gated anion channel TMEM16A, thus depolarizing the cell and opening voltage-gated calcium channels. This mechanism strongly amplified the pericyte [Ca2+]i rise and capillary constriction evoked by contractile agonists and ischemia. In a rodent stroke model, TMEM16A inhibition slowed the ischemia-evoked pericyte [Ca2+]i rise, capillary constriction, and pericyte death; reduced neutrophil stalling; and improved cerebrovascular reperfusion. Genetic analysis implicated altered TMEM16A expression in poor patient recovery from ischemic stroke. Thus, pericyte TMEM16A is a crucial regulator of cerebral capillary function and a potential therapeutic target for stroke and possibly other disorders of impaired microvascular flow, such as Alzheimer’s disease and vascular dementia.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号