首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23680篇
  免费   1640篇
  国内免费   600篇
耳鼻咽喉   534篇
儿科学   124篇
妇产科学   223篇
基础医学   1713篇
口腔科学   1894篇
临床医学   1474篇
内科学   2206篇
皮肤病学   1805篇
神经病学   786篇
特种医学   857篇
外国民族医学   1篇
外科学   4381篇
综合类   2831篇
现状与发展   1篇
预防医学   566篇
眼科学   3952篇
药学   1532篇
  9篇
中国医学   511篇
肿瘤学   520篇
  2024年   78篇
  2023年   395篇
  2022年   819篇
  2021年   1008篇
  2020年   808篇
  2019年   699篇
  2018年   680篇
  2017年   740篇
  2016年   821篇
  2015年   731篇
  2014年   1300篇
  2013年   1495篇
  2012年   1093篇
  2011年   1267篇
  2010年   1083篇
  2009年   1092篇
  2008年   1088篇
  2007年   1081篇
  2006年   963篇
  2005年   884篇
  2004年   819篇
  2003年   738篇
  2002年   647篇
  2001年   631篇
  2000年   504篇
  1999年   409篇
  1998年   422篇
  1997年   404篇
  1996年   337篇
  1995年   308篇
  1994年   295篇
  1993年   265篇
  1992年   242篇
  1991年   232篇
  1990年   191篇
  1989年   162篇
  1988年   152篇
  1987年   149篇
  1986年   135篇
  1985年   159篇
  1984年   146篇
  1983年   101篇
  1982年   96篇
  1981年   72篇
  1980年   57篇
  1979年   33篇
  1978年   32篇
  1977年   19篇
  1976年   13篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Erb:YAG and Hol:YAG laser ablation rates of fibrocartilage and nucleus pulposus were measured in vitro simulating clinical conditions. After ablation macroscopic and microscopic appearance of the ablation site was investigated. Hol:YAG and Erb:YAG laser mean ablation rates increased almost linearly with rising energies, showing higher total ablation rates for the Hol:YAG laser due to its higher achievable energy density. At comparable energy densities the Erb:YAG laser appears to be more effective with respect to the corresponding ablation rates. Consequently, the ablational threshold proved to be lower for the Erb:YAG laser. Whereas during Hol:YAG laser ablation, some smoke formation and considerable tissue shrinking occurred, these effects could not be observed during Erb:YAG laser ablation. Consequently macroscopic and microscopic inspection showed some thermal damage after Hol:YAG and only minimal alterations after Erb:YAG laser ablation. Adjacent thermal damage was determined and proved to be lower for the Erb:YAG laser. In our opinion the characteristics of each laser system provide certain advantages for special clinical indications.  相似文献   
62.
采用双波长薄层扫描法测定新疆雪莲芦丁含量。以乙酸乙酯一甲酸一水(67:13:20)为展开剂,硅胶GF254薄层析分离;测定波长λs为263nm,参比波长λR为235nm。样品回收率为97.3%;相对标准偏差为2.8%。在芦T0.5~6.0μg范围内有良好的线性,相关系数为0.999。本法简便、快速、灵敏度高。  相似文献   
63.
Summary To characterize and compare the pathologic, hemodynamic and electrocardiographic changes of both transeatheter laser and electrical energy on ventricle, 33 subendocardial myocardium lesions were induced at energy 60, 120 and 240 Joules by either transcatheter laser irradiation or electrical shock in 7 anesthetized dogs. The following results were observed: 1) Both laser and electrical ablation on myocardium created nonhomogeneous myocardium injury, but laser ablation caused mainly focal tissue vaporization and necrosis, while electrical shock induced widespread tissue degenerations; 2) Both laser and electrical induced-lesion dimensions increased parallel to the total dosage of energy; 3) Laser ablation caused mainly (90%) single ventricular premature beats and 86 % of them occurred within the first minute after energy discharged, while ventricular tachycardias were found in any electrical energy groups; ventricular fibrillations occurring during laser and electrical ablation were 5 % and 13 % respectively (P< 0.01): 4) A decrease in aortic blood pressure and an increase in central verous pressure induced by laser ablation were significantly less than that produced by the same amount of electrical energy (P<0.0l). Our preliminary results have shown that transeatheter laser ablation has great potential for becoming a practical method in the management of refractory tachycardias.  相似文献   
64.
65.
弱激光血疗法的发展及展望   总被引:3,自引:1,他引:2  
本文主要介绍了弱激光血疗的机制及其在我国的发展过程.弱激光血疗法起源于前苏联的紫外光量子疗法,传入我国后经历了静脉内照射疗法,离体血液激光照射回输疗法,口咽部照射伴吸氧疗法,鼻腔内照射疗法等.本文对各种疗法的特点及临床应用进行了详细叙述.有些学者认为,中医的观点也能揭示激光血疗的机制.从中医辨证的角度,人的体质分为虚证和实证.结合中医针灸的虚则补之,实则泻之的原理,根据患者的虚实状况,采用含有中医补泻信息的调制激光照射血液,同时加照相关敏感穴位,促进疗效,以体现中医的辨证施治的原则可取得更好的疗效.  相似文献   
66.
大鼠肺微血管和肺泡铸型的扫描电镜观察   总被引:2,自引:0,他引:2  
用扫描电镜观察以甲基丙烯酸甲酯灌注鼠的肺微血管和肺泡。胸膜下毛细血管较稀疏,网孔粗大。毛细血管部分成锐角折返,亦可见毛细血管盲端。肺泡隔毛细血管均成扁平状膨大,且相互吻合成单层密集网。肺泡铸型为大小不等、不规则的多面体,表面可见肺泡Ⅱ型细胞核之压迹。两肺泡之间可见呈桥式连接的肺泡孔,亦可见部分呈三通管样相连。  相似文献   
67.
Vitiligo is a skin disease with a worldwide prevalence ranging from 0.5% to 4%. Conservative therapies include photochemotherapy, phototherapy with UVB radiation (broadband UVB 290–320 nm, narrow band UVB 311 nm), systemic steroids and pseudocatalase. Modern therapeutic options include treatment with topical immunomodulators (tacrolimus, pimecrolimus), analogues of vitamin D3, excimer laser and surgery/transplantation. Our analysis compares these therapies for vitiligo and the evidence levels supporting their effectiveness. Conclusions: The face and neck respond best to all therapeutic approaches, while the acral areas are least responsive. For generalized vitiligo, phototherapy with UVB radiation is most effective with the fewest side effects; PUVA is the second best choice.Topical corticosteroids are the preferred drugs for localized vitiligo. They may be replaced by topical immunomodulators which display comparable effectiveness and fewer side effects.The effectiveness of vitamin D analogues is controversial with limited data. Surgical therapy can be very successful, but requires an experienced surgeon and is very demanding of time and facilities, thus limiting its widespread use. L-phenylalanine therapy appears effective on the face but enjoys neither widespread use nor extensive data support. No single therapy for vitiligo can be regarded as the most effective as the success of each treatment modality depends on the type and location of vitiligo.  相似文献   
68.
CO2激光治疗宫颈糜烂2412例疗效观察   总被引:2,自引:0,他引:2  
目的 探讨CO2激光治疗宫颈糜烂的疗效。方法 采用CO2激光输出功率20-40w,波长10.6μm,针对轻、中、重不同糜烂程度采用不同光束强度,光斑直径约0.3-0.5的连续波治疗宫颈糜烂2412例。结果 术后三个月复查,总有效率100%。结论 CO2激光治疗术简单、安全、疗效满意,适用于治疗I-Ⅲ0宫颈糜烂。  相似文献   
69.
The aim of this study was to evaluate corneal innervation in soft contact lens wearers using the Tomey Confoscan confocal microscope (40x/0.75 objective lens). Three distinct age- and sex-matched subject groups were involved, including extended soft (hydrogel and silicone-hydrogel) contact lens wearers, overnight soft (hydrogel) contact lens wearers, and non contact lens wearers. A number of variables were objectively measured, subjectively evaluated, or graded in order to investigate the distribution and morphology of corneal nerves. For most of the evaluated parameters, no statistically significant differences were found. However, qualitative observations showed noticeable differences in corneal nerve appearance among the different subject groups; the degree of corneal oedema was suggested as the main causative factor. In conclusion, neither the short-term (overnight wear) nor the long-term (12-month extended wear) soft contact lens wear appeared to affect the morphology and/or distribution of corneal nerves as viewed with confocal microscopy.  相似文献   
70.
Standard imaging techniques using a curved linear array echoendocope are summarized to facilitate the attainment of expertise in endoscopic ultrasonography and endoscopic ultrasound‐guided fine needle aspiration, and to promote the widespread use of this diagnostic and therapeutic tool. Typical images of the mediastinal organs, the bilio‐pancreatic systems and neighboring organs by scanning from the esophagus, stomach, duodenal bulb, and descending portion of the duodenum, are shown in a sequential manner. The basic techniques of endoscopic ultrasound‐guided fine needle aspiration are also presented.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号