全文获取类型
收费全文 | 356700篇 |
免费 | 63442篇 |
国内免费 | 17973篇 |
专业分类
耳鼻咽喉 | 3937篇 |
儿科学 | 7726篇 |
妇产科学 | 5836篇 |
基础医学 | 47101篇 |
口腔科学 | 9867篇 |
临床医学 | 48113篇 |
内科学 | 66424篇 |
皮肤病学 | 10218篇 |
神经病学 | 27665篇 |
特种医学 | 12071篇 |
外国民族医学 | 125篇 |
外科学 | 42954篇 |
综合类 | 43696篇 |
现状与发展 | 64篇 |
一般理论 | 67篇 |
预防医学 | 22743篇 |
眼科学 | 8979篇 |
药学 | 34411篇 |
229篇 | |
中国医学 | 15518篇 |
肿瘤学 | 30371篇 |
出版年
2024年 | 925篇 |
2023年 | 4313篇 |
2022年 | 10715篇 |
2021年 | 15083篇 |
2020年 | 14935篇 |
2019年 | 19011篇 |
2018年 | 18863篇 |
2017年 | 19162篇 |
2016年 | 19335篇 |
2015年 | 23351篇 |
2014年 | 26192篇 |
2013年 | 25748篇 |
2012年 | 24885篇 |
2011年 | 26702篇 |
2010年 | 22661篇 |
2009年 | 16563篇 |
2008年 | 17171篇 |
2007年 | 15932篇 |
2006年 | 15469篇 |
2005年 | 15052篇 |
2004年 | 10639篇 |
2003年 | 9635篇 |
2002年 | 8477篇 |
2001年 | 7748篇 |
2000年 | 7678篇 |
1999年 | 7521篇 |
1998年 | 4187篇 |
1997年 | 4161篇 |
1996年 | 3203篇 |
1995年 | 2970篇 |
1994年 | 2554篇 |
1993年 | 1680篇 |
1992年 | 2514篇 |
1991年 | 2192篇 |
1990年 | 1819篇 |
1989年 | 1576篇 |
1988年 | 1398篇 |
1987年 | 1284篇 |
1986年 | 1023篇 |
1985年 | 816篇 |
1984年 | 522篇 |
1983年 | 409篇 |
1982年 | 248篇 |
1981年 | 216篇 |
1980年 | 200篇 |
1979年 | 259篇 |
1978年 | 152篇 |
1977年 | 115篇 |
1974年 | 118篇 |
1973年 | 99篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Fabrication of porous hollow silica nanoparticles and their applications in drug release control. 总被引:11,自引:0,他引:11
Preparation and characterization of porous hollow silica nanoparticles (PHSN) for controlled release applications were investigated. Through orthogonally designed experiments, the optimal synthesis conditions for the preparation of PHSN were obtained and the produced PHSN were characterized by BET, SEM, TEM and IR. Scanning and transmission electron microscopy images revealed their hollow shell-core structure and also demonstrated that the size and shape of PHSN are determined by the templating CaCO3 nanoparticles. The produced PHSN were applied as a carrier to study the controlled release behaviors of Brilliant Blue F (BB), which was used as a model drug. Being loaded into the inner core and on the surfaces of the nanoparticles, BB was released slowly into a bulk solution for about 1140 min as compared to only 10 min for the normal SiO2 nanoparticles, thus exhibited a typical sustained release pattern without any burst effect. In addition, higher BET of the carriers, lower pH value and lower temperature prolonged BB release from PHSN, while stirring speed showed little influence on the release behavior. It showed that PHSN have a promising future in controlled drug delivery applications. 相似文献
102.
103.
Birgit Herting MD Bettina Beuthien‐Baumann MD Katrin Pöttrich PhD Markus Donix MD Antje Triemer PhD Johannes B. Lampe MD Rüdiger von Kummer MD Karl Herholz MD Heinz Reichmann MD Vjera A. Holthoff MD 《Movement disorders》2007,22(4):490-497
Depressive symptoms are common in patients with neurodegenerative disorders. Imaging studies suggest that a disruption of frontal-subcortical pathways may underlie depression associated with basal ganglia disease. This pilot study tested the hypothesis that frontal dysfunction contributes to depression associated with multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). Depressed patients with MSA (n = 11), PSP (n = 9), and age-matched controls (n = 25) underwent measures of cerebral glucose metabolism applying positron emission tomography with (18)F-fluorodeoxyglucose. Regional metabolism in the patient groups was compared to the normal subjects using the voxel-based statistical parametric mapping. Depressive symptom severity (Hamilton Depression Rating) and degree of locomotor disability (Hoehn & Yahr) were assessed in the patient groups. The association between prefrontal metabolism and the occurrence of depressive symptoms and the degree of locomotor disability was investigated. When compared to controls, MSA patients revealed significant metabolic decreases in bilateral frontal, parietal, and cerebellar cortex and in the left putamen. In PSP patients, significant hypometabolism was demonstrated in bilateral frontal cortex, right thalamus, and midbrain. Depression severity but not the patients' functional condition was significantly associated with dorsolateral prefrontal glucose metabolism in both patient groups. The findings of this pilot study support the hypothesis that depressive symptoms in MSA and PSP are associated with prefrontal dysfunction. 相似文献
104.
105.
Ting-Kai Leung Chien-Jui Cheng Chi-Ming Lee Li-Kuo Shen Hung-Jung Wang Ya-Yen Chen 《中华医学杂志(英文版)》2005,118(17):1493-1496
The current report focuses on two patients of the same age who presented similar appearances on initial anteroposterior chest images. Follow-up images showed superoanterior and superoposterior mediastinal lesions. The first patient with noninvasive cystic thymoma was suspected before surgery, while the pathologic diagnosis was intrathoracic phrenic nerve schwannoma. The second patient was with an asymmetric, dumbbell-shaped paravertebral tumor over T3 and T4 on the left side. The preoperative… 相似文献
106.
Yusen Chen Jun Nakura Jing-Ji Jin Zhihong Wu Miyuki Yamamoto Michiko Abe Yasuharu Tabara Yoshikuni Yamamoto Michiya Igase Xiao Bo Katsuhiko Kohara Tetsuro Miki 《Hypertension research》2003,26(6):439-444
The beta-adrenoceptor (beta-AR)-stimulatory guanine nucleotide-binding (Gs) protein system has been shown to play important roles in the cardiovascular system. The gene encoding the alpha-subunit of Gs proteins (GNAS1) is a candidate genetic determinant for hypertension. Because alcohol consumption is known to affect blood pressure partly through the beta-AR-Gs protein system, we examined the possible interaction between GNAS1 T393C polymorphism and drinking status in the association with hypertension in the present study. As a result, a non-significant but reasonable trend supporting the presence of an interaction was shown (p = 0.076). In line with this trend, the T393C polymorphism significantly interacted with drinking status in the association with systolic blood pressure (p = 0.028). Moreover, supporting the presence of an interaction, T allele carriers consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than CC homozygotes in non-drinkers and light drinkers. In contrast, CC homozygotes consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than T allele carriers in moderate to heavy drinkers. The present study also showed a significant interaction between the T393C polymorphism and drinking status in the association with pulse pressure (p = 0.026), reflected by a significant association between the T393C polymorphism and pulse pressure in moderate to heavy drinkers (p = 0.026). These findings may be helpful in conducting further molecular and biological studies on the relationship among the effects of alcohol, the beta-AR-Gs protein system, and hypertension. 相似文献
107.
108.
109.
Amyloidosis is a systemic disease that usually occurs in the gastrointestinal tract or in muscular or adipose tissue. Primary amyloidosis of the urinary bladder is a rare disease that can mimic bladder cancer on cystoscopic examination as well as in its clinical presentation of painless gross hematuria. This report describes a 49-year-old male with repeated painless gross hematuria, who underwent transurethral resection of a suspected bladder tumor. Pathologic examination revealed papillary urothelial hyperplasia with vascular ectasia and no signs of malignancy. Massive gross hematuria occurred 2.5 years later. Cystoscopy showed multiple papillary lesions with yellowish-brown submucosal plaques on the posterior bladder wall. A second transurethral tumor resection was performed and histologic examination revealed plasma cell infiltration and eosinophilic amorphous deposits in the subepithelial stroma and vascular wall. The deposits were positive for Congo red and apple-green birefringence under polarized light examination but negative for Masson's trichrome stain, indicating that they were not fibrotic in nature. Hence, the diagnosis of amyloidosis of the urinary bladder was confirmed. Screening for amyloidosis was negative in other organ systems and the patient has remained disease-free up to the last follow-up 4 years after the second transurethral resection. Amyloidosis should be considered in the differential diagnosis of patients with recurrent hematuria who have symptoms characteristic of bladder cancer but negative pathologic study for malignancy. Correct diagnosis relies on clinical alertness and the use of a special staining technique during pathologic examination. 相似文献
110.
目的探讨用游离自体腹白线片修补急性十二指肠溃疡穿孔的应用价值。方法从2006年1月至2006年7月对13例用自体腹白线片修补急性十二指肠溃疡穿孔的病人的临床资料和随访情况进行回顾性分析,其中2例穿孔大于2cm2,平均手术时间60分钟,平均失血量20ml,平均住院天数9±1天。结果游离自体腹白线片修补急性十二指肠溃疡穿孔13例均痊愈出院。随访15天至6个月,无手术并发症。结论本方法操作较简单、安全、效果好,其适应症广,是一种可行的新方法。 相似文献