全文获取类型
收费全文 | 28484篇 |
免费 | 3117篇 |
国内免费 | 1949篇 |
专业分类
耳鼻咽喉 | 309篇 |
儿科学 | 504篇 |
妇产科学 | 555篇 |
基础医学 | 2694篇 |
口腔科学 | 438篇 |
临床医学 | 3299篇 |
内科学 | 3771篇 |
皮肤病学 | 329篇 |
神经病学 | 1369篇 |
特种医学 | 994篇 |
外国民族医学 | 11篇 |
外科学 | 3423篇 |
综合类 | 5470篇 |
现状与发展 | 7篇 |
一般理论 | 2篇 |
预防医学 | 2487篇 |
眼科学 | 482篇 |
药学 | 3050篇 |
33篇 | |
中国医学 | 2003篇 |
肿瘤学 | 2320篇 |
出版年
2024年 | 144篇 |
2023年 | 569篇 |
2022年 | 1344篇 |
2021年 | 1744篇 |
2020年 | 1331篇 |
2019年 | 1049篇 |
2018年 | 1081篇 |
2017年 | 1101篇 |
2016年 | 968篇 |
2015年 | 1508篇 |
2014年 | 1785篇 |
2013年 | 1932篇 |
2012年 | 2551篇 |
2011年 | 2554篇 |
2010年 | 1824篇 |
2009年 | 1435篇 |
2008年 | 1608篇 |
2007年 | 1457篇 |
2006年 | 1302篇 |
2005年 | 1151篇 |
2004年 | 791篇 |
2003年 | 783篇 |
2002年 | 677篇 |
2001年 | 524篇 |
2000年 | 427篇 |
1999年 | 340篇 |
1998年 | 148篇 |
1997年 | 177篇 |
1996年 | 129篇 |
1995年 | 113篇 |
1994年 | 107篇 |
1993年 | 60篇 |
1992年 | 121篇 |
1991年 | 106篇 |
1990年 | 91篇 |
1989年 | 77篇 |
1988年 | 81篇 |
1987年 | 68篇 |
1986年 | 55篇 |
1985年 | 37篇 |
1984年 | 26篇 |
1983年 | 20篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1971年 | 8篇 |
1970年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Bruce Ho PhD Woodrew Chao Reza Sadri Lu Huang Ricky Taira Henry Shih 《Journal of digital imaging》1995,8(4):180-190
A key advantage in the conversion from film-based to digital radiology is the possibility of a long-term on line electronic archival of patient studies. The popular approach based on optical disk jukeboxes for the long-term archive and magnetic disk storage for data caching is not economically attractive because of the cost of both the jukebox and the medium. Strategies for extending the archival system design with a tape jukebox have been studied. The proposed strategy calls for the use of high-ratio lossy compression together with low-cost tape storage to make long-term on line archiving more affordable. An intelligent prefetching algorithm based on hospital information system and radiologic information system triggers, which in turn are augmented by manual case preparation, can effectively overcome the longer latency of ad hoc retrievals. This longer latency is caused by both system-level bottlenecks and the sequential access constraint of the tape drive. Strategies for image clustering and tape allocation by patient classification also enhance retrieval efficiency. This archival design using image compression, prefetching, and clustering could be implemented in many of the existing teleradiology and picture archiving and communication systems. 相似文献
82.
Lung preservation solution substrate composition affects rat lung oxidative metabolism during hypothermic storage 总被引:1,自引:0,他引:1
Peltz M Hamilton TT He TT Adams GA Koshy S Burgess SC Chao RY Jessen ME Meyer DM 《Respiratory physiology & neurobiology》2005,148(3):2771-283
Lungs harvested for transplantation utilize oxygen after procurement. We investigated the effects of storage solution substrate composition on pulmonary oxidative metabolism and energetics during the preservation interval. Rat lungs were harvested and stored at 10 degrees C in low-potassium dextran (LPD) solution. Groups of lungs were preserved with preservation solution containing 5mM carbon-13 ((13)C) labeled glucose or increasing concentrations of (13)C labeled pyruvate. Additional groups of rat lungs were studied with dichloroacetate (DCA) added to the pyruvate-modified preservation solutions. Oxidative metabolism (measured by (13)C-enrichment of glutamate) and adenine nucleotide levels were quantified. Increasing preservation solution pyruvate concentration augmented glutamate (13)C-enrichment up to a concentration of 32mM pyruvate. DCA further stimulated oxidative metabolism only at lower concentrations of pyruvate (4 and 8mM). ATP and ADP were not different among groups, but AMP levels were higher in the glucose group. These data suggest that altering the substrate composition of the preservation solution influences lung metabolism during allograft preservation for transplantation. 相似文献
83.
Evidence for platelet-activating factor as a late-phase mediator of chronic pancreatitis in the rat. 总被引:3,自引:0,他引:3 下载免费PDF全文
W. G. Zhou W. Chao B. A. Levine M. S. Olson 《The American journal of pathology》1990,137(6):1501-1508
The role of platelet-activating factor (PAF) as a mediator of pancreatic inflammation was examined in the rat pancreatic duct ligation model of obstructive pancreatitis. Pancreatic generation of PAF, as measured by bioassay (ie, platelet [3H]serotonin secretion), was determined at various times after induction of inflammation. Tissue levels of PAF in the normal pancreas averaged 600 +/- 49 pg/g, but PAF was not detectable during the initial 24 hours of pancreatitis, a time when the inflammatory reaction would be considered acute, that is, during the period of maximal serum amylase release and the development of interstitial edema. However a substantial increase in pancreatic PAF levels (12 times control levels) was observed 7 to 14 days after duct ligation during the late-phase response interval similar to the situation characteristic of chronic pancreatitis in which parenchymal atrophy, fibrosis, and pancreatic insufficiency evolve. One week after duct ligation when PAF levels peaked, an evaluation was made of the effects of PAF antagonists (BN52021 and WEB2170) on pancreatic lesions using Evan's blue extravasation, pancreatic myeloperoxidase (MPO) activity, and acid phosphatase activity in peritoneal lavage fluid. BN52021 or WEB2170 treatment was shown to reduce pancreatic damage and inflammation significantly. Long-term in vivo administration of exogenous PAF (20 micrograms/kg/hr for 7 days) exhibited a reduction of [3H]thymidine uptake into and amylase release from pancreatic acini in vitro. Our observations 1) that pancreatic PAF levels increased significantly during the chronic phase of obstructive pancreatitis induced by duct ligation; 2) that inhibition of the action of PAF, through specific receptor antagonism, caused an attenuation of pancreatic lesions; and 3) that chronic administration of PAF resulted in decreased pancreatic regeneration and exocrine function are consistent with a pivotal role for PAF as a late-phase inflammatory mediator in chronic pancreatitis in rats. 相似文献
84.
Ching-Yu Lin Angel Chao Yuh-Cheng Yang Hung-Hsueh Chou Chih-Ming Ho Ruey-Wen Lin Ting-Chang Chang Jia-Yia Chiou Fang-Yu Chao Kung-Liahng Wang Tsai-Yen Chien Swei Hsueh Chu-Chun Huang Chien-Jen Chen Chyong-Huey Lai 《Journal of clinical virology》2008,42(4):361-367
BACKGROUND: Type-specific persistence of human papillomavirus (HPV) infection can cause invasive cervical cancer. OBJECTIVES: To evaluate the efficacy of HPV detection and typing with a general polymerase chain reaction (PCR)-based genotyping array and to compare it with a type-specific PCR assay. STUDY DESIGN: Four hundred and thirty-three cervical samples were tested with a modified MY11/GP6+ PCR-based reverse-blot assay (EasyChip HPV Blot; King Car, Taiwan [hereafter HPV Blot]) and with 20 genotypes of L1-type-specific PCR (HPV-6, -11, -16, -18, -31, -33, -35, -39, -45, -51, -52, -53, -56, -58, -59, -62, -66, -68, -70, and -71 [CP8061]). RESULTS: The concordance of the two tests in determining HPV positivity was 96.8% (419/433), with a Cohen's kappa=0.93 (95% CI: 0.90-0.97) and McNemar's test of P=1.0, which indicates excellent agreement. The overall concordance of the two tests in the identification of type-specific HPV was 91.0% (394/433). Sensitivity (90-100%), specificity (99.2-100%), and accuracy (98.6-100%) rates of HPV Blot against the gold standard were satisfactory for HPV-16, -18, -58, -33, -52, -39, -45, -31, -51, -70 while HPV-71 (63.6%) had suboptimal sensitivity. Though the kappa values between the two tests for many individual genotypes could not be reliably calculated because of low positivity, the kappa values for HPV-16, -52, and -58 were excellent (0.93, 0.96, and 0.95, respectively). CONCLUSION: The modified MY11/GP6+ PCR-based HPV Blot assay is accurate and sensitive for detection and genotyping of HPV in cervical swab samples. 相似文献
85.
Dendritic cells (DC) are specialized antigen-presenting cells. DC can acquire and process antigens in the periphery before maturing and migrating to secondary lymphoid tissues where they present the antigens and deliver co-stimulatory signals to T cells. We describe an immunostimulatory oligonucleotide containing a CpG motif that stimulated murine DC to up-regulate co-stimulatory molecules, induce T-cell proliferative responses and secrete interleukin-12 in vitro. Administration of this oligonucleotide, but not of a control oligonucleotide lacking this motif, to mice led to the disappearance of DC from the marginal zone and T-cell areas of spleen, but not from heart or kidney. The same CpG did not cause maturation of monocyte-derived human DC in vitro, but lipopolysaccharide-treated monocyte-derived DC showed enhanced functional activity and up-regulated co-stimulatory molecules. 相似文献
86.
儿童早期发展对个人成年时期,乃至老年阶段的全面发展和健康促进均具有重要意义,受到越来越多的社会关注。本文从早期教育中运动能力培养的角度,总结其对儿童早期体格生长、智力发展、神经心理发育的作用及对特殊儿童疾病干预的影响,为促进儿童健康成长寻找途径和方向。 相似文献
87.
目的分析老年慢性病患者肺部感染与白细胞分化抗原14(CD14)和人类白细胞抗原(HLA)基因多态性的关系。方法选取2017年10月-2019年10月菏泽市单县中心医院老年慢性疾病患者615例,以其中合并肺部感染者97例(15.77%)为研究组,另在未合并肺部感染者中随机抽取92例为对照组,采集两组临床资料,检测并比较两组CD14-159 C/T、CD14-260 C/T和HLA-A、HLA-B和HLA-DRB1基因分布。结果两组患者性别、年龄、体质量指数(BMI)及基础疾病等临床资料比较差异无统计学意义,研究组合并慢性疾病种类较对照组多(P<0.05);两组CD14-159 C/T基因型分布差异显著(P<0.05),研究组CD14-159 C等位基因频率显著低于对照组,T等位基因频率显著高于对照组(P<0.05),两组CD14-260 C/T基因型及等位基因频率比较差异无统计学意义;研究组HLA-A*0101等位基因频率高于对照组,HLA-B*5201和HLA-DRB1*1502等位基因频率低于对照组,差异有统计学意义(P<0.05)。结论合并慢性疾病种类较多的老年慢性疾病患者容易发生肺部感染,感染可能与CD14和HLA基因多态性有关,CD14-159 TT和HLA-A*0101可能为易感基因。 相似文献
89.
目的:报告成人室间隔缺损的外科治疗经验。方法:对26例成人室间隔缺损的手术治疗进行回顾性分析。其中行室缺直接缝合3例,单纯补片修补19例,单向活瓣补片修补4例。同时行主动脉瓣折叠悬吊2例,双瓣置换l例,二尖瓣成成形l例,三尖瓣成形4例.结果:无手术死亡。术后并发症:切口感染、术后出血二次开胸止血、呼吸道感染和片周漏各l例,心动过速4例.术后随访24例(92.3%),随访时间1月~92月,晚期死亡l例,死因为片周漏并感染性心内膜炎.结论:成人室间隔缺损的临床表现虽较为复杂,手术效果令人满意.选择正确的手术方法及注意围术期处理是手术治疗成功的关键。 相似文献
90.
目的 :研究Schafer列线图在确定前列腺手术适应证中的作用。方法 :对 45例前列腺增生症 (BPH)患者进行了压力 -流率测定 ,经Schafer列线图和线性被动尿道阻力关系 (Lin -PURR)定量分析BPH患者膀胱出口梗阻 (BOO)程度和逼尿肌收缩强度。结果 :本组患者无BOO和轻度BOO者为 2 0 .0 % ,逼尿肌收缩强度很弱者为 8.9% ,不适合前列腺手术者为 2 8.8%。结论 :对BPH患者术前作出准确的评价 ,在前列腺治疗的方法选择方面有十分重要的意义 相似文献