全文获取类型
收费全文 | 1709篇 |
免费 | 83篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 159篇 |
妇产科学 | 7篇 |
基础医学 | 136篇 |
口腔科学 | 34篇 |
临床医学 | 104篇 |
内科学 | 433篇 |
皮肤病学 | 25篇 |
神经病学 | 102篇 |
特种医学 | 104篇 |
外科学 | 314篇 |
综合类 | 96篇 |
预防医学 | 81篇 |
眼科学 | 17篇 |
药学 | 100篇 |
中国医学 | 2篇 |
肿瘤学 | 74篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 29篇 |
2020年 | 15篇 |
2019年 | 31篇 |
2018年 | 33篇 |
2017年 | 17篇 |
2016年 | 31篇 |
2015年 | 32篇 |
2014年 | 46篇 |
2013年 | 43篇 |
2012年 | 68篇 |
2011年 | 89篇 |
2010年 | 73篇 |
2009年 | 69篇 |
2008年 | 75篇 |
2007年 | 74篇 |
2006年 | 101篇 |
2005年 | 46篇 |
2004年 | 62篇 |
2003年 | 53篇 |
2002年 | 45篇 |
2001年 | 55篇 |
2000年 | 69篇 |
1999年 | 59篇 |
1998年 | 63篇 |
1997年 | 34篇 |
1996年 | 43篇 |
1995年 | 29篇 |
1994年 | 26篇 |
1993年 | 26篇 |
1992年 | 17篇 |
1991年 | 22篇 |
1990年 | 16篇 |
1989年 | 25篇 |
1988年 | 34篇 |
1987年 | 24篇 |
1986年 | 17篇 |
1985年 | 29篇 |
1984年 | 15篇 |
1983年 | 23篇 |
1982年 | 15篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 14篇 |
1974年 | 7篇 |
1973年 | 7篇 |
排序方式: 共有1800条查询结果,搜索用时 15 毫秒
81.
MC Chau SF Leung KM Kam KY Cheung WH Kwan KH Yu KW Chiu TC Chan 《Journal of Medical Imaging and Radiation Oncology》2007,51(5):480-484
To assess the dosimetric effect of using interpolated contours in planning intensity‐modulated radiation therapy (IMRT) for advanced T‐stage nasopharyngeal carcinoma. The present study focused on T3–T4 tumours where the proximity of targets to neurological organs poses a stringent test on the feasibility of such an approach. Contours of targets and organs were delineated on CT images of 2.5‐mm interval and a reference IMRT plan was generated. An investigative (INV) IMRT plan was then generated with the same planning protocol, but based on interpolated contours that replaced deleted contours on alternate slices. The reference and INV plans were compared. Regarding target coverage, all targets in the INV plans met the acceptance criteria except for the PTV in one case. Regarding organs, the mean dose to 1% volume of the brainstem and spinal cord in the INV plans were kept below their dose limits. No significant differences in the mean doses to others organs were found. Satisfactory target coverage and protection of critical organs to a degree similar to full‐scale contouring could be achieved with use of interpolated contours. The saving in manpower time for contouring is expected to significantly improve the throughput of the IMRT planning process. 相似文献
82.
Hepatic metallothionein as a source of zinc and cysteine during the first year of life 总被引:1,自引:0,他引:1
Metallothionein, a high cysteine-containing protein, can bind with both essential and nonessential metals and thus play an important role as a metal storage protein and also in the detoxification of toxic metals. Although in the human fetus, levels of trace minerals and metallothionein are very high, their postnatal changes are not well documented. The purpose of the present investigation, therefore, was to quantify the accumulation of metallothionein in premature and full-term infants during the first year of life and to identify factors affecting its accumulation. From 47 postmortem samples, it was determined that hepatic metallothionein levels were highest in newborn premature and full-term infants falling to levels found in older children by 4.4 months of age. Hepatic zinc levels were also highest in the youngest infants, falling with increasing postnatal age. There was a significant positive correlation between zinc and metallothionein at all ages. However, there was a negative correlation between hepatic metallothionein levels and cystathionase activity. Hepatic copper and metallothionein levels were unrelated. The renal concentration of metallothionein, zinc, and copper were significantly lower than corresponding hepatic levels. The fall in hepatic levels of zinc and metallothionein during the first months of life correspond to a period of negative zinc balance and low endogenous cysteine production in the newborn. Thus metallothionein may play an important role as a storage depot for these two essential nutrients during this critical period of active growth. 相似文献
83.
1 In this study, we have investigated the vasodilator response to acetylcholine under diabetes conditions in isolated renal arteries of rabbits. We have also examined the contribution of endothelium-derived nitric oxide (EDNO) and endothelium-derived hyperpolarizing factor (EDHF) to the endothelium-dependent relaxation caused by acetylcholine in the renal arteries of alloxan-induced diabetic rabbits. 2 Acetylcholine (10(-10) - 10(-4) M) produced cumulative concentration-response curve in the renal arteries of both control and diabetic rabbits. The EC50 values and maximal responses to acetylcholine were not significantly different relative to diabetic conditions. In order to isolate the EDHF component of acetylcholine-induced vasodilator response, L-nitro-methyl arginine ester (L-NAME, 10(-4) M) and indomethacin (10(-6) M) were added to the Krebs' solution throughout the experiment. Under these conditions, acetylcholine induced vasodilatation in the isolated renal arteries from both control and diabetic rabbits. The vasodilator response to acetylcholine was not affected under diabetic conditions. 3 Sodium nitroprusside (SNP)-induced relaxation was increased in the diabetic rabbits compared with the control animals. 4 Tetrabutyl ammonium (TBA, 0.5 mM) produced a significant reduction in acetylcholine-induced vasodilatation in both preparations from control and diabetic animals, consistent with involvement of K+ channels in mediating this response. Glibenclamide (1 microM) attenuated acetylcholine-induced vasodilatation in preparations from control animals only, while iberiotoxin (0.05 microM) significantly reduced the vasodilator response to acetylcholine in preparations from both control and diabetic animals. 5 The role of EDNO in mediating acetylcholine-induced vasodilatation was examined. The vascular preparations were incubated with 20 mM K(+)-Krebs' solution to inhibit the EDHF contribution to acetylcholine-induced vasodilatation. Under this condition, acetylcholine induced a vasodilator response in both preparations from control and diabetic rats. Pretreatment with L-NAME (10(-4) M) attenuated acetylcholine-induced vasodilatation in both preparations, indicating an nitric oxide-mediated vasodilator response. 6 Our results indicated that acetylcholine-induced vasodilatation in the isolated renal arteries of alloxan-induced diabetic rabbits was not affected under diabetic conditions. Acetylcholine-induced vasodilatation is mediated by two vasodilator components; namely, EDHF and EDNO. The contribution of EDHF and EDNO to acetylcholine-induced vasodilatation was not affected under diabetic conditions and there was no indication of endothelial dysfunction associated with diabetes. EDHF component was found to act mainly through high conductance Ca(2+)-activated K+ channels under normal and diabetic conditions, while the adenosine triphosphate-dependent K+ channels were involved in mediating acetylcholine vasodilator response in the control preparations only. 相似文献
84.
Posthemorrhagic ventricular dilation in the neonate: development and characterization of a rat model
Cherian SS Love S Silver IA Porter HJ Whitelaw AG Thoresen M 《Journal of neuropathology and experimental neurology》2003,62(3):292-303
Intraventricular hemorrhage is a common complication of prematurity. Posthemorrhagic ventricular dilation (PHVD) has a high rate of disability and no safe and effective treatment. Its pathogenesis is poorly understood, largely because of the lack of a satisfactory animal model. We have developed a model of neonatal PHVD in the rat. Seven-day-old (P7) Wistar rat pups were given 80-microl injections of citrated rat blood or artificial cerebrospinal fluid (CSF) into alternate lateral ventricles on P7 and P8. Intracranial pressure was monitored and increased briefly by over 8-fold. Some rats received further 10-microl intraventricular injections of India ink on P21. Animals were weighed daily and simple neurologic tests performed. On P21 (or P22 if India ink had been injected), the rats were perfusion-fixed and blocks processed for paraffin histology. Sixty-five percent of pups injected with blood and 50% injected with artificial CSF developed dilated lateral ventricles, with patchy loss of ependyma, marked astrocytic gliosis, and rarefaction of periventricular white matter. India ink injection revealed slow transit of CSF from the dilated lateral ventricles but eventual passage into the subarachnoid space. Pups that had received intraventricular injections but did not develop ventricular dilation nonetheless had lighter brains than littermate controls (p < 0.001). Body weights were not significantly different from controls. Hydrocephalic animals had reduced motor performance as assessed by a grip traction test (p = 0.0002). This model is well suited to studying the pathogenesis of PHVD. 相似文献
85.
86.
A 50-year-old man was diagnosed as having absent pulmonary valve syndrome with aneurysmal dilatation of the pulmonary arteries. He also had a large subaortic ventricular septal defect and severe aortic regurgitation. He underwent successful intracardiac repair and aortic valve replacement. This case is presented in view of its rarity and controversies in the surgical management. 相似文献
87.
Deltopectoral flap and pectoralis major flaps form the basis of most reconstructions following ablative surgeries of head and neck region for cancers. There are many papers reporting acute complications but the literature on one late complication i.e. secondaries at flap donor site is rare. This is one such report and review of literature. 相似文献
88.
Idiopathic hypertrophic cranial pachymeningitis 总被引:6,自引:0,他引:6
Idiopathic hypertrophic cranial pachymeningitis is a rare form of fibrosing chronic inflammatory process of unknown etiology, which causes thickening of the intracranial dura mater. We present four patients with hypertrophic cranial pachymeningitis who presented with chronic headache and cranial nerve palsies. The diagnosis of idiopathic hypertrophic cranial pachymeningitis was based on neuroimaging findings of thickened enhancing dura, exclusion of known causes and histopathologic findings compatible with nonspecific inflammation in the meningeal biopsies. Corticosteroid therapy was effective in all cases in inducing a complete or partial remission of the neurologic symptoms and signs. We describe the clinical, radiological and pathological features of idiopathic hypertrophic cranial pachymeningitis and discuss the relationship of this entity with other inflammatory fibrosclerotic disorders to explain the pathogenesis. A high index of suspicion, prompt confirmation of the diagnosis by meningeal biopsy, and early institution and long-term maintenance of steroid therapy may help to prevent irreversible neurologic sequelae, especially blindness. 相似文献
89.
Bhat MR Cherian SM Shetty JN 《Indian journal of dermatology, venereology and leprology》2002,68(2):103
An 18-year-old female who presented with features suggestive of pigmented xerodermoid is reported. 相似文献
90.
Khan S Roy A Christopher DJ Cherian AM 《Journal of the Indian Medical Association》2002,100(11):643-4, 655
Asthma and related allergic disorders are reported to be rare in poor and developing countries and their prevalence is expected to rise with urbanisation. Investigation was carried to see the prevalence of asthma and asthma-related symptoms by using a simple questionnaire-based data collection. One hundred and twenty bank employees were studied in the age group 25-55 years in 4 centres of Vellore town. A one-page questionnaire in English regarding asthma and allergic symptoms was used to assess the prevalence and the details of medical care utilisation by those who were asthmatics. The prevalence of self-reported bronchial asthma was 8.3% and that of asthma-related symptoms 15.8%. A significant number of subjects with symptoms suggestive of asthma self-reported themselves as non-asthmatic. There was a significant association between those who had symptoms of asthma and a positive family history of asthma. Most of the asthmatic subjects using allopathic medicines reported a poor quality of life, despite treatment. The prevalence of asthma in Vellore town is more than that reported in other studies carried out at different centres in India. The prevalence may actually be higher since a significant number of subjects with symptoms suggestive of asthma reported themselves as non-asthmatic subjects. As expected, positive family history was forthcoming in subjects with asthma symptoms. Most asthmatic subjects have not experienced a significant improvement in their quality of life, which could indicate sub-optimal management. These findings can form the basis for further studies to investigate factors that lead to these variations. 相似文献