全文获取类型
收费全文 | 1223篇 |
免费 | 53篇 |
国内免费 | 66篇 |
专业分类
耳鼻咽喉 | 95篇 |
儿科学 | 60篇 |
妇产科学 | 11篇 |
基础医学 | 140篇 |
口腔科学 | 44篇 |
临床医学 | 162篇 |
内科学 | 243篇 |
皮肤病学 | 36篇 |
神经病学 | 14篇 |
特种医学 | 254篇 |
外科学 | 85篇 |
综合类 | 30篇 |
预防医学 | 54篇 |
眼科学 | 23篇 |
药学 | 40篇 |
中国医学 | 4篇 |
肿瘤学 | 47篇 |
出版年
2021年 | 12篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 20篇 |
2014年 | 18篇 |
2013年 | 27篇 |
2012年 | 25篇 |
2011年 | 22篇 |
2010年 | 36篇 |
2009年 | 45篇 |
2008年 | 25篇 |
2007年 | 66篇 |
2006年 | 36篇 |
2005年 | 22篇 |
2004年 | 16篇 |
2003年 | 19篇 |
2002年 | 25篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 24篇 |
1998年 | 64篇 |
1997年 | 74篇 |
1996年 | 74篇 |
1995年 | 63篇 |
1994年 | 48篇 |
1993年 | 52篇 |
1992年 | 28篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 53篇 |
1988年 | 32篇 |
1987年 | 47篇 |
1986年 | 21篇 |
1985年 | 28篇 |
1984年 | 17篇 |
1983年 | 27篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 20篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1973年 | 14篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1969年 | 7篇 |
1967年 | 4篇 |
排序方式: 共有1342条查询结果,搜索用时 0 毫秒
51.
小鼠皮肤超氧化物歧化酶活性与枸杞多糖的干预 总被引:1,自引:0,他引:1
目的:观察枸杞多糖对皮肤胶原代谢和自由基产生的影响,探讨其抗皮肤衰老的作用。方法:实验于2005-06/2006-05在广东医学院整形外科研究所完成。①实验材料:清洁级昆明小鼠60只,月龄2个月,体质量16~24g,雌雄各半。②实验分组:将小鼠随机分为正常对照组、衰老模型组和抗衰老模型组,每组20只。③实验干预:模型组每日用D-半乳糖溶液皮下注射制造衰老模型,用量和时间为80mg/(kg·d)7d,120mg/(kg·d)14d,140mg/(kg·d)14d,180mg/(kg·d)7d。正常对照组每日注射同体积的生理盐水。抗衰老模型组在注射D-半乳糖期间以枸杞多糖灌胃,剂量为20mg/(kg·d),正常对照组和衰老组则以同体积的生理盐水代之灌胃。④实验评估:42d后切取小鼠颈背部皮肤,测定超氧化物歧化酶活力、羟脯氨酸和丙二醛含量。结果:56只小鼠进入结果分析(4只死亡)。①小鼠皮肤超氧化物歧化酶活力:与正常对照组相比,衰老组和抗衰老组小鼠皮肤超氧化物歧化酶活力降低,差异有显著性意义(P<0.01);抗衰老组与衰老模型组比较,超氧化物歧化酶活力增加,差异有显著性意义(P<0.01)。②与正常对照组相比,衰老组和抗衰老组小鼠皮肤羟脯氨酸和丙二醛含量增加,差异有显著性意义(P<0.01);抗衰老组与衰老组比较,羟脯氨酸和丙二醛含量均降低,差异有显著性意义(P<0.01)。结论:枸杞多糖改善皮肤老化的作用与提高小鼠皮肤超氧化物歧化酶活力,降低羟脯氨酸、丙二醛含量,影响胶原代谢有关。 相似文献
52.
Efficient gene delivery to multipotential hematopoietic stem cells would greatly facilitate the development of effective gene therapy for certain hematopoietic disorders. We have recently described a rapid multiparameter sorting procedure for significantly enriching stem cells with competitive long-term lymphomyeloid repopulating ability (CRU) from 5-fluorouracil (5-FU)-treated mouse bone marrow. The sorted cells have now been tested as targets for retrovirus-mediated delivery of a marker gene, NeoR. They were cocultured for 4 days with fibroblasts producing a high titer of retrovirus in medium containing combinations of the hematopoietic growth factors interleukin-3 (IL-3), IL-6, c-kit ligand (KL), and leukemia inhibitory factor (LIF) and then injected into lethally irradiated recipients, together with sufficient "compromised" bone marrow cells to provide short-term support. Over 80% of the transplanted mice displayed high levels (> or = 20%) of donor- derived leukocytes when analyzed 4 to 6 months later. Proviral DNA was detected in 87% of these animals and, in half of them, the majority of the hematopoietic cells were marked. Thus, infection of the stem cells was most effective. The tissue and cellular distribution of greater than 100 unique clones in 55 mice showed that most sorted stem cells had lymphoid as well as myeloid repopulating potential. Secondary transplantation provided strong evidence for infection of very primitive stem cells because, in several instances, different secondary recipients displayed in their marrow, spleen, thymus and day 14 spleen colony-forming cells the same proviral integration pattern as the primary recipient. Neither primary engraftment nor marking efficiency varied for stem cells cultured in IL-3 + IL-6, IL-3 + IL-6 + KL, IL-3 + IL-6 + LIF, or all four factors, but those cultured in IL-3 + IL-6 + LIF appeared to have lower secondary engraftment potential. Provirus expression was detected in 72% of the strongly marked mice, albeit often at low levels. Highly efficient retroviral marking of purified lymphomyeloid repopulating stem cells should enhance studies of stem cell biology and facilitate analysis of genes controlling hematopoietic differentiation and transformation. 相似文献
53.
Soubhagya R. Nayak Ashwin Krishnamurthy SJ Madhan Kumar Latha V. Prabhu Bhagath Kumar Potu Sujatha D’Costa Anu Vinod Ranade 《Hand (New York, N.Y.)》2010,5(1):31-36
The superficial palmar arch (SPA) and its contributing arteries are highly variable. The palmar type of median artery (PMA)
can be involved in the formation of the SPA by replacing the superficial palmar branch of the radial artery (RA) or the ulnar
artery (UA). The present study was undertaken to investigate the presence of the PMA and its contribution in the formation
of SPA in 42 cadavers (84 upper limbs) of Indian origin. When there was a PMA, its outer diameter was measured in the carpal
tunnel. The PMA was found in 13 upper limbs (15.4%), and of these ten incidences (11.9%), the PMA took part in the formation
of SPA, and in three instances (3.5%), the PMA did not make up part of the SPA. Out of the ten cases in which the PMA contributed
to the formation of SPA, in six cases (7.1%), the PMA anastomosed with the UA; in three cases (3.5%), the PMA anastomosed
with both the UA and the RA, and in one incidence (1.1%), the PMA joined the arteria radialis indicis (deep branch of the
RA) to complete the SPA. The outer diameters of the median arteries varied between 0.8 and 2.6 mm with the mean value of 1.7 mm.
The present study concludes that the median–ulnar type of SPA was the most common type of SPA when the PMA was encountered
as a source of superficial arterial arcade of the hand, followed by the radial–median–ulnar type. The vascular patterns found
in this study are important to hand surgeons. The present study of PMA origin, course, and its contribution to the SPA will
add to the existing knowledge of the vascular anatomy of forearm and hand. 相似文献
54.
55.
G S Berke D M Moore B R Gerratt D G Hanson M Natividad 《American journal of otolaryngology》1989,10(3):181-187
We investigated the effect of variation in superior laryngeal nerve stimulation (SLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three SLNS frequencies (100 Hz, 130 Hz, and 160 Hz) using a constant rate of air flow. Increasing SLNS, which causes a contraction of the cricothyroid muscle, produced a marked increase in Fo, little change in Psub, an increase in the open quotient, and a decrease in the closed quotient of the glottal cycle. 相似文献
56.
Office-based system for voice analysis 总被引:2,自引:0,他引:2
G S Berke D G Hanson T K Trapp D M Moore B R Gerratt M Natividad 《Archives of otolaryngology--head & neck surgery》1989,115(1):74-77
There has been recent growing interest in the analysis of various electronically recorded signals as potential tools for objective assessment of vocal dysfunction. In the past, analysis of such signals required an expensive multitrack FM recorder, mainframe computer system, customized software, and significant time commitment. This report describes an adaptation of commercially available components that allow digital recording of multiple electronic signals, storage of data, and subsequent signal analysis using an inexpensive personal microcomputer system. Commercially available software for manipulation and examination signals is discussed as adapted for examination of glottographic and acoustic signals. The relatively inexpensive availability of similar computer systems will, hopefully, encourage assessment of the clinical applications of objective techniques of voice quality. 相似文献
57.
G S Berke D M Moore B R Gerratt D G Hanson T S Bell M Natividad 《The Laryngoscope》1989,99(9):977-982
The present investigation was designed to examine the effect of variation in recurrent laryngeal nerve stimulation (RLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three fundamental frequencies (F0) (100 Hz, 130 Hz, and 160 Hz) for RLNS, using a constant rate of air flow. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the open quotient (OQ), and an increase in the closing quotient (CQ). Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS. 相似文献
58.
D C Green G S Berke P H Ward B R Gerratt 《The Annals of otology, rhinology, and laryngology》1992,101(11):883-887
Intralaryngeal injections of botulinum toxin (Botox), under electromyographic guidance, have emerged as an effective treatment for adductor spasmodic dysphonia. To remain effective, these injections must be repeated every 3 to 9 months as the symptoms recur. One drawback to the current method is the need for electromyographic confirmation of needle placement into the thyroarytenoid muscle. This report describes an anatomic approach to Botox injection that requires only flexible nasopharyngeal endoscopy and careful evaluation of the anatomic landmarks. This technique has been used successfully on 13 patients, and objective pretreatment and posttreatment measures are reported. 相似文献
59.
Carriage of Haemophilus influenzae and Streptococcus pneumoniae in healthy Chinese and Vietnamese children in Hong Kong 总被引:1,自引:0,他引:1
RYT Sung JM Ling SM Fung SJ Oppenheimer DW Crook JTF Lau AFB Cheng 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(11):1262-1267
Nasopharyngeal carriage of Haemophilus influenzae and Streptococcus pneumoniae was studied in 621 healthy Chinese children and 300 healthy Vietnamese children aged from 2 months to 5 years in Hong Kong. The carriage rate of H, influenzae type b in Vietnamese children was 1.3% (CI 0.04-2.63%); it was zero in Chinese. The carriage rate of non-typable H. influenzae was 5.8% (CI 1.4-7.6%) in Chinese and 65.4% (CI 58.9-69.8%) in Vietnamese. The carriage rates of S. pneumoniae were 10.8% (CI 8.3-13.2%) and 55.7% (CI 50.1-61.3%) in Chinese and Vietnamese children, respectively. Univariate and multivariate logistic regression analyses were performed to search for factors associated with differences in carriage rates of both H. influenzae and S. pneumoniae between Chinese and Vietnamese children. Although older age, smaller living area and parental smoking were associated with higher carriage rates, these could not explain the remarkably low carriage rates of both bacteria in Chinese children. 相似文献
60.
Synovial sarcoma of the head and neck 总被引:2,自引:0,他引:2
Synovial sarcoma, a malignant soft-tissue tumor that occurs primarily in the extremities, is seen rarely in the head and neck. Although known to behave aggressively in the extremities, recent reports suggest that the course of synovial sarcoma may be more indolent when it occurs in the head and neck. Five new cases of synovial sarcoma of the head and neck are described herein. Of four patients with adequate follow-up, three died of pulmonary metastases at 1, 2 1/2, and 8 years following initial treatment. The fourth patient is alive with disease at the primary site six years after diagnosis. The poor prognosis for patients with this disease suggests that aggressive treatment is necessary. 相似文献