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   17835篇
  免费   1340篇
  国内免费   415篇
耳鼻咽喉   458篇
儿科学   80篇
妇产科学   188篇
基础医学   938篇
口腔科学   1316篇
临床医学   1154篇
内科学   1493篇
皮肤病学   1422篇
神经病学   382篇
特种医学   561篇
外国民族医学   1篇
外科学   4022篇
综合类   2137篇
现状与发展   1篇
预防医学   383篇
眼科学   3509篇
药学   839篇
  8篇
中国医学   359篇
肿瘤学   339篇
  2024年   59篇
  2023年   287篇
  2022年   546篇
  2021年   782篇
  2020年   631篇
  2019年   529篇
  2018年   514篇
  2017年   592篇
  2016年   673篇
  2015年   574篇
  2014年   1048篇
  2013年   1148篇
  2012年   885篇
  2011年   1013篇
  2010年   869篇
  2009年   877篇
  2008年   842篇
  2007年   827篇
  2006年   767篇
  2005年   687篇
  2004年   634篇
  2003年   535篇
  2002年   440篇
  2001年   461篇
  2000年   360篇
  1999年   278篇
  1998年   301篇
  1997年   288篇
  1996年   256篇
  1995年   209篇
  1994年   214篇
  1993年   194篇
  1992年   165篇
  1991年   156篇
  1990年   131篇
  1989年   114篇
  1988年   105篇
  1987年   108篇
  1986年   90篇
  1985年   110篇
  1984年   93篇
  1983年   62篇
  1982年   47篇
  1981年   36篇
  1980年   29篇
  1979年   8篇
  1978年   10篇
  1977年   3篇
  1974年   1篇
  1972年   1篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
31.
目的:观察蛙皮素(BBS)对前列腺癌PC-3细胞骨架形态及细胞内游离Ca2+([Ca2+]i)浓度的影响。方法:①利用免疫荧光法(IH),结合激光扫描共聚焦显微镜(LSCM)检测10-5mol/L浓度BBS处理的PC-3细胞角蛋白(CK)的表达,以反映其对细胞骨架形态的影响;②应用Fluo-3/AM荧光标记技术和LSCM检测不同浓度BBS(10-9、10-7、10-5mol/L)处理的PC-3细胞[Ca2+]i浓度。结果:①10-5mol/L浓度的BBS可促进PC-3细胞CK表达及伪足形成;②BBS可提高PC-3细胞[Ca2+]i浓度,并具有浓度依赖性。结论:实验证明一定浓度的BBS可明显提高PC-3细胞[Ca2+]i浓度及CK表达,进而影响PC-3细胞骨架形态。本研究为探索BBS应用于肿瘤研究以及BBS作用后细胞内信息传递途径提供了基础。  相似文献   
32.
BACKGROUND/PURPOSE: Laser-induced autofluorescence spectroscopy provides excellent possibilities for medical diagnostics of different tissue pathologies including cancer. However, to create the whole picture of pathological changes, investigators collect spectral information from patients in vivo or they study different tumor models to obtain objective information for fluorescent properties of every kind of healthy and diseased tissue. Therefore, it is very important to find the most appropriate, and close to the human skin, animal samples from the fluorescence point of view, which will allow the extrapolation of the animal data to human spectroscopic diagnostics. METHODS: In the present work, we examined the autofluorescence properties of different animal skin tissues, which are considered as the most common skin models. A nitrogen laser was used as an excitation source. Samples of healthy mouse, chicken and pig skin in vivo and/or ex vivo were studied and were compared with results obtained from investigations of healthy human skin in vivo. RESULTS AND CONCLUSION: Specific features of the recorded spectra are discussed and the possible origin of the obtained fluorescence signals is proposed. Quantitative evaluation of data extrapolation for each skin type is also depicted.  相似文献   
33.
强脉冲光治疗浅表(皮肤)血管瘤临床观察   总被引:4,自引:4,他引:0  
目的:观察强脉冲光(IPL)治疗浅表(皮肤)血管瘤的疗效。方法:选择60例浅表(皮肤)血管瘤患者,随机分为治疗组和对照组,治疗组用535nm、580nm强脉冲光治疗皮损,每三周治疗一次,三次为一个疗程;对照组采用波长为532nm的Q开关Nd:YAG激光治疗,每两周治疗一次,三次为一个疗程。观察两组皮损的治愈率、并发症等情况,并行统计学处理。结果:治疗组皮损三次治愈率明显高于对照组(P〈0.01),患处瘢痕形成及炎症性色素沉着发生率均低于对照组。结论:强脉冲光(IPLTM)治疗浅表(皮肤)血管瘤效果满意。  相似文献   
34.
玻璃体切割联合激光治疗增殖性糖尿病性视网膜病变   总被引:1,自引:0,他引:1  
目的:观察分析玻璃体切割联合激光治疗增殖性糖尿病性视网膜病变的疗效及充填材料选择.方法:分析426例472眼增殖性糖尿病性视网膜病变的患者行玻璃体切割,膜剥离切除,眼内电凝,激光光凝并根据情况选用眼内充填材料.结果:术后随访6-12个月,448/472眼(占95%)一次视网膜解剖复位成功,除1眼术后合并中央静脉阻塞,1眼合并中央动脉阻塞,8眼视网膜脱离术后复发视力下降外,其余均有不同程度提高.视力0.05以上362眼(76.7%),与术前相比有显著性差异(P>0.05),46眼视力大于0.2.结论:玻璃体切割手术联合激光治疗是挽救增殖性糖尿病性玻璃体视网膜病变患者最终失明的有效方法.  相似文献   
35.
36.
Abstract— NdYAG laser-induced modification of the root surface may inhibit development of external inflammatory resorption in replanted teeth. This study tested this hypothesis in vivo. The pulp chambers of six mandibular premolars in each of two dogs were accessed, inoculated with plaque, and sealed (Groups 1, 2). Two additional premolars in each dog were endodontically treated without inoculation (Groups 3, 4). After 2 weeks, teeth were hemisected and extracted. Each root had a 2times3 mm surface area denuded of cementum on the buccal and lingual surface. In Groups 1 (n= 12 roots) and 3 (n=4), the denuded surfaces were wiped with 15% EDTA, coated with black ink, and irradiated with Nd:YAG laser (0.75 W, 15 ppc, 300 pm tip, 20 s). In Groups 2 (n= 12) and 4 (n= 4), the surfaces were wiped with 15% EDTA, and rinsed with sterile saline for 20 s. Roots were replanted within 5 min. The dogs were perfwion-euthanised 10 weeks after replantation. Block specimens were removed, decalcified, embedded and horizontally sectioned (6 pm) at 180-pm intervals, resulting in 10 to 14 cross-sections of each root. From these, the middle five consecutive sections were stained with hematoxylin and eosin, and observed by light microscopy for occurrence of surface, inflammatory and replacement resorption on the denuded surfaces. No obvious differences were noted between the laser-irradiated and non-irradiated surfaces. Inflammatory resorption was frequent in Groups 1 and 2, and absent in Groups 3 and 4. Replacement resorption was minimal in Groups 1 and 2, and frequent in Groups 3 and 4. Differences between Groups 1 and 2, and between Groups 3 and 4 were not significant, whereas the differences between the two pairs of groups were statistically significant (chi-square and two-way ANOVA, P>0.006). These results did not support the hypothesis, and questioned the clinical validity of the surface modification in NdYAG laser-irradiated den-tin. Therefore, the clinical application of NdYAG laser to the root surfaces of replanted teeth is not warranted.  相似文献   
37.
金陈进  高汝龙 《眼科学报》1993,9(4):175-178
应用激光干涉视力仪检测了23例(23只眼)膜性白内障Nd:YAG激光切开术前及术后的干涉视力,结果显示:术前与术后干涉视力之间的差异无显著性(P>0.05)。术前干涉视力与术后矫正视力呈正相关(P<0.05),提示半透明膜性白内障对激光干涉视力无显著影响.激光干涉视力是反映术后视力康复的可靠方法.但在具体分析时,应注意假阴性和假阳性的可能.65.2%的眼术后矫正视力高于术后干涉视力,反映了高度屈光不正的无晶体眼对激光干涉条纹在视网膜上的形成有一定的影响.  相似文献   
38.
The purpose of the present study was to analyse clinically failed and retrieved implants prior to and after cleaning by means of scanning electron microscopy (SEM) and X-ray induced photoelectron spectroscopy (XPS) as compared to unused controls. Six different chemical and physical techniques for cleaning of contaminated titanium implants were evaluated: 1) rinsing in absolute ethanol for 10 min, 2) cleaning in ultrasonic baths containing trichloroethylene (TRI) and absolute ethanol, 10 min in each solution, 3) abrasive cleaning for 30 s, 4) cleaning in supersaturated citric acid for 30 s, 5) cleaning with continuous CO2-laser in dry conditions at 5 W for 10 s, 6) cleaning with continuous CO2-laser in wet conditions (saline) at 5 W for 10 s. SEM of failed implants showed the presence of contaminants of varying sizes and XPS showed almost no titanium but high carbon signals. XPS of unused titanium implants showed lower levels of titanium as previously reported, probably due to contamination of carbon which increased with time in room air. Cleaning of used implants in citric acid followed by rinsing with deionized water for 5 min followed by cleaning in ultrasonic baths with TRI and absolute ethanol gave the best results with regard to macroscopical appearance and surface composition. However, as compared to the unused implants the results from an element composition point of view were still unsatisfactory. It is concluded that further development and testing of techniques for cleaning of organically contaminated titanium is needed.  相似文献   
39.
With the invention of the laser, many clinical disciplines have taken advantage of this new energy source. Its precision, intensity and energy density is superior to all other known surgical devices. Based on the principle of light amplification from a photon-emitting resonator, the monochromaticity, collimation and coherence provide the high-energy density of the laser beam for medical applications. The state-of-the-art and future potential of laser use in cardiovascular diseases will be reviewed. Most of the work in this field has been accomplished during the past decade with numerous research projects. Although many technical advances have been made, so far the results in cardiovascular medicine are in the areas of vessel anastomosis, ablation of conduction passes for arrhythmia therapy, and angioplasty. In this paper, special attention will be given to the recent success in XeCl excimer laser application for photodecomposition of tissue with a goal of improved recanalization. The high-power density of the XeCl excimer laser provides significant advantages for the disruption of both embolic and calcified plaque. Regardless of the type of tissue ablated, gross, histologic, and ultra-structural analysis confirmed the absence of thermal injury in luminar recanalization as well as in animal studies. Progress in the manufacture of catheters, with multiple very small diameter fibers, led to the decisive breakthrough in clinical laser angioplasty. Peripheral as well as coronary arteries have been successfully recanalized followed by balloon dilatation. The ease of application and the success achieved thus far have resulted in an optimistic assessment for laser medicine.  相似文献   
40.
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