全文获取类型
收费全文 | 44500篇 |
免费 | 4216篇 |
国内免费 | 2680篇 |
专业分类
耳鼻咽喉 | 543篇 |
儿科学 | 509篇 |
妇产科学 | 481篇 |
基础医学 | 4688篇 |
口腔科学 | 1212篇 |
临床医学 | 5682篇 |
内科学 | 6056篇 |
皮肤病学 | 445篇 |
神经病学 | 1918篇 |
特种医学 | 1500篇 |
外国民族医学 | 13篇 |
外科学 | 4460篇 |
综合类 | 8808篇 |
现状与发展 | 8篇 |
一般理论 | 12篇 |
预防医学 | 3418篇 |
眼科学 | 1093篇 |
药学 | 4573篇 |
43篇 | |
中国医学 | 2742篇 |
肿瘤学 | 3192篇 |
出版年
2024年 | 166篇 |
2023年 | 584篇 |
2022年 | 1429篇 |
2021年 | 1865篇 |
2020年 | 1500篇 |
2019年 | 1261篇 |
2018年 | 1323篇 |
2017年 | 1282篇 |
2016年 | 1131篇 |
2015年 | 1932篇 |
2014年 | 2455篇 |
2013年 | 2596篇 |
2012年 | 3690篇 |
2011年 | 3974篇 |
2010年 | 2821篇 |
2009年 | 2481篇 |
2008年 | 2844篇 |
2007年 | 2896篇 |
2006年 | 2582篇 |
2005年 | 2373篇 |
2004年 | 1617篇 |
2003年 | 1586篇 |
2002年 | 1245篇 |
2001年 | 1049篇 |
2000年 | 905篇 |
1999年 | 770篇 |
1998年 | 457篇 |
1997年 | 427篇 |
1996年 | 295篇 |
1995年 | 271篇 |
1994年 | 219篇 |
1993年 | 136篇 |
1992年 | 150篇 |
1991年 | 126篇 |
1990年 | 104篇 |
1989年 | 91篇 |
1988年 | 122篇 |
1987年 | 105篇 |
1986年 | 67篇 |
1985年 | 63篇 |
1984年 | 38篇 |
1983年 | 31篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1980年 | 18篇 |
1979年 | 54篇 |
1978年 | 16篇 |
1975年 | 19篇 |
1974年 | 20篇 |
1972年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Feng-Yuan Liu Chien-Yu Lin Joseph T Chang Shu-Hang Ng Shy-Chyi Chin Hung-Ming Wang Chun-Ta Liao Sheng-Chieh Chan Tzu-Chen Yen 《Journal of nuclear medicine》2007,48(10):1614-1619
Conventional work-up (CWU) with chest radiography, abdominal ultrasonography, and skeletal scintigraphy has limited value in M staging of nonkeratinizing nasopharyngeal carcinoma (NPC). Our aim was to evaluate whether (18)F-FDG PET could replace CWU by comparing their diagnostic efficacies. METHODS: Patients with histologically proven nonkeratinizing NPC and no prior treatment were prospectively enrolled. All study participants underwent CWU and (18)F-FDG PET for primary M staging. Distant metastasis was considered to be present if there was any reliable evidence identified within 1 y after diagnosis. The comparative diagnostic efficacies of (18)F-FDG PET, CWU, and the combination of (18)F-FDG PET and CWU (PET+CWU) were evaluated using the areas under the receiver-operating-characteristic (ROC) curves. RESULTS: Sixty-one (20.3%) of 300 eligible patients were found to have distant metastases. On a patient-based analysis, (18)F-FDG PET was found to be more effective than CWU (P < 0.001), whereas it was equally effective with PET+CWU (P = 0.130). On region-based analyses, (18)F-FDG PET was more effective than skeletal scintigraphy and chest radiography for detecting bone metastases (P < 0.001) and chest metastases (P < 0.001), respectively. (18)F-FDG PET and abdominal ultrasound were equally effective for detecting hepatic metastases (P = 0.127). On region-based analyses, the combination of (18)F-FDG PET and CWU did not yield any noticeable increase in diagnostic efficacy. CONCLUSION: (18)F-FDG PET can replace CWU in primary M staging of nonkeratinizing NPC. 相似文献
82.
目的探讨眶骨延长术扩大眶容积治疗眼球突出的可行性。方法1年龄山羊6只,环行截开右侧眶壁,于眶上壁放置延长器,侧向延长1.5cm,经大体、X线、干骨标本及组织学观察成骨情况。结果6只山羊眶骨得到不同程度的侧向延长,延长侧随着眶骨容量的增加,眼球突度较自身对照侧为小。结论眶骨延长术可造成山羊眶骨侧向移位,有可能成为治疗眼球过度突出的方法之一。 相似文献
83.
[目的]利用医院局域网对医院感染进行实时监控,提高工作效率。[方法]采用Windows98平台,应用Access建立数据库,进行感染监控。[结果]局域网使用方便、操作简单,使医院感染监控及时、准确。[结论]利用医院局域网对医院感染可进行实时性监控,减轻了医护人员和专职人员的工作量,提高了工作效率。 相似文献
84.
内固定与带血管髂骨块治疗青壮年股骨颈骨折 总被引:3,自引:0,他引:3
[目的]探讨内固定与带旋髂深血管蒂髂骨块移植治疗青壮年股骨颈骨折的手术方法及临床疗效.[方法]对15例青壮年股骨颈骨折行切开复位,空心螺钉或HDS内固定并同时切取带旋髂深血管蒂的髂骨块转位移植.[结果]15例均获随访,随访时间平均2 a 5个月,骨折全部愈合,1例发生股骨头缺血坏死.[结论]内固定加带旋髂深血管蒂髂骨块转位移植是治疗青壮年股骨颈骨折的最佳手术方式. 相似文献
85.
Bing Feng P. Hendrik Pretorius Troy H. Farncombe Seth T. Dahlberg Manoj V. Narayanan Miles N. Wernick Anna M. Celler Jeffrey A. Leppo Michael A. King 《Journal of nuclear cardiology》2006,13(3):354-361
BACKGROUND: Dynamic single photon emission computed tomography (SPECT) acquisition and reconstruction of early poststress technetium 99m teboroxime washout images has been shown to be useful in the detection of coronary disease. Assessment of poststress regional wall motion may offer additional use in assessing coronary disease. Our goal was to investigate the feasibility of simultaneously imaging myocardial ischemia and transient poststress akinesis using gated-dynamic SPECT. METHODS AND RESULTS: A gated-dynamic mathematical cardiac torso (MCAT) phantom was developed to model both teboroxime kinetics and cardiac regional wall motion. A lesion was simulated as having delayed poststress teboroxime washout together with a transient poststress wall motion abnormality. Gated projection data were created to represent a 3-headed SPECT system undergoing a total rotation of 480 degrees . The dynamic expectation-maximization reconstruction algorithm with postsmoothing across gating intervals by Wiener filtering, and the ordered-subset expectation maximization reconstruction algorithm with 3-point smoothing across gating intervals were compared. Compared with the ordered-subset expectation maximization with 3-point smoothing, the dynamic expectation-maximization algorithm with Wiener filtering was able to produce visually higher-quality images and more accurate left ventricular ejection fraction estimates. CONCLUSION: From simulations, we conclude that changing cardiac function and tracer localization possibly can be assessed by using a gated-dynamic acquisition protocol combined with a 5-dimensional reconstruction strategy. 相似文献
86.
87.
目的我们前期的实验结果显示A20 mRNA和蛋白在人脑胶质瘤组织及细胞系(U251、U87、BT325)中高表达,本研究拟构建A20RNAi载体,并检测其对U251细胞A20表达的抑制作用。方法构建三种针对人A20基因的真核干涉表达载体,以脂质体法将其分别转染人脑胶质瘤细胞系U251,以RT-PCR、蛋白印迹法检测各干涉载体对U251细胞中A20mRNA和蛋白表达的抑制作用。结果成功构建三种针对A20基因的RNAi载体,经RT-PCR、蛋白印迹检测筛选出对A20基因干涉效果最佳的载体,命名为pSilencer3.1-A20R1。结论成功构建A20基因干涉载体,为进一步探讨A20与脑胶质瘤恶性增殖、血管形成以及抗凋亡的关系奠定实验基础。 相似文献
88.
目的探讨软组织血管瘤多排CT血管成像的影像表现方法回顾性分析临床、手术及病理证实20例软组织血管瘤CT平扫、增强和CT血管成像的不同表现结果CT平扫病灶呈软组织密度,5例灶内或灶缘见斑点状或斑块状高密度钙化灶;20例增强后病灶血管成像呈不同表现,12例动脉期瘤体内呈网状血管强化并见明显的瘤体供血动脉,其中单支供血动脉4例,2支以上多支供血动脉8例,供血动脉较对侧明显增粗瘤体内明显迂曲静脉血管6例,而静脉期瘤体表现为网状血管阴影强化8例病变动脉期瘤体不强化或仅轻微强化,且无明显供血动脉参与供血,静脉期瘤体逐渐均匀一致强化结论软组织血管瘤的多排螺旋CT血管成像可清晰显示软组织血管瘤的形态、大小、供血血管 相似文献
89.
CT重建椎弓根轴线投影点定位研究 总被引:7,自引:0,他引:7
目的:建立椎弓根螺钉最佳入钉点,提高椎弓根螺钉内固定术的准确性和安全性。方法:高速螺旋CT共扫描检查40例国人的200个L1~L5脊椎。重建后测量400个椎弓根的入点坐标(x,y),即椎弓根轴线在椎骨后表面的投影点与后正中线的距离(x)及与横突中线的垂直距离(y)。结果:x坐标从L1~L5逐渐增大,男性大于女性(P<0.05);y坐标从L1到L4逐渐下移,在L4与横突中线接近重叠,但L5突然上升,与L2节段水平相当,L1~L5y坐标基本上都在横突中线以上,但每组数据变异较大。就y坐标而言,椎弓根轴线投影点与传统入点比较均有差异。结论:横突中线是椎弓根螺钉置入的重要参照标志,但椎弓根轴线投影点并不在横突中线上,不同个体、节段之间y坐标存在的较大差异是高误置率发生的重要原因。对个体而言,术前常规通过CT测量椎弓根轴线在椎骨后表面的投影点数据对椎弓根螺钉的置入有重要指导意义。 相似文献
90.
BACKGROUND: Cutaneous metastasis from adenoid cystic carcinoma of the salivary gland is very rare. OBJECTIVE: To present an unusual case of cutaneous metastasis from adenoid cystic carcinoma of the right parotid gland. METHODS: A 63-year-old woman with multiple subcutaneous nodules on the abdomen and a gradually enlarged mass over the right parotid area was examined. A skin biopsy was taken from one of the abdominal nodules. RESULT: Skin biopsy demonstrated the characteristic histopathologic features of metastatic adenoid cystic carcinoma. A subsequent computerized tomography of the head and neck revealed a huge soft tissue mass involving the right parotid gland. Computerized tomography of the chest revealed extensive nodular pleural thickening, and pleural biopsy also showed typical histopathologic features of metastatic adenoid cystic carcinoma. All of these results are consistent with the diagnosis of an adenoid cystic carcinoma of the right parotid gland with disseminated metastases. CONCLUSION: We report a rare case of cutaneous metastasis from adenoid cystic carcinoma of the right parotid gland. The presentation of cutaneous metastasis is often nonspecific and may mimic benign lesions. Subcutaneous nodules that are rapidly developing or eruptive, are rapidly growing and have stony hardness in nature, have pain or tenderness, and have nonhealing ulceration remind us of the possibility of cutaneous metastases. Dermatologists and dermatologic surgeons should keep the diagnosis of cutaneous metastasis in mind and always perform skin biopsy when encountering these lesions. 相似文献