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   1677篇
  免费   119篇
  国内免费   7篇
耳鼻咽喉   8篇
儿科学   144篇
妇产科学   43篇
基础医学   267篇
口腔科学   8篇
临床医学   98篇
内科学   250篇
皮肤病学   28篇
神经病学   105篇
特种医学   16篇
外科学   319篇
综合类   101篇
预防医学   89篇
眼科学   19篇
药学   153篇
中国医学   5篇
肿瘤学   150篇
  2023年   10篇
  2022年   24篇
  2021年   59篇
  2020年   27篇
  2019年   34篇
  2018年   36篇
  2017年   24篇
  2016年   34篇
  2015年   27篇
  2014年   37篇
  2013年   44篇
  2012年   85篇
  2011年   95篇
  2010年   56篇
  2009年   68篇
  2008年   71篇
  2007年   81篇
  2006年   58篇
  2005年   56篇
  2004年   36篇
  2003年   36篇
  2002年   54篇
  2001年   41篇
  2000年   26篇
  1999年   33篇
  1998年   11篇
  1997年   12篇
  1995年   17篇
  1994年   17篇
  1993年   16篇
  1992年   27篇
  1991年   36篇
  1990年   25篇
  1989年   32篇
  1988年   25篇
  1987年   22篇
  1986年   36篇
  1985年   18篇
  1984年   19篇
  1983年   15篇
  1981年   9篇
  1979年   16篇
  1975年   15篇
  1974年   18篇
  1973年   12篇
  1972年   10篇
  1971年   13篇
  1970年   16篇
  1966年   10篇
  1958年   8篇
排序方式: 共有1803条查询结果,搜索用时 15 毫秒
61.
Controversy exists regarding the validity of follicular lesion of undetermined significance (FLUS), an indeterminate diagnostic category of The Bethesda System for Reporting Thyroid Cytopathology (BSRTC). According to BSRTC, FLUS carries a 5–15% risk of cancer. This study was designed to determine if cytomorphology could stratify FLUS into subgroups with different risks of malignancy. Reports of 127 consecutive FNAs reported as FLUS with subsequent tissue diagnoses were evaluated for the presence of various cytologic features and the results were correlated with histological diagnoses. FLUS cases with focal nuclear atypia (nuclear overlap/crowding, nuclear grooves/membrane irregularities, nuclear enlargement, and/or nuclear pseudoinclusions) were more frequently malignant on excision whereas those with architectural atypia (microfollicles) were more often benign on excision (P < 0.05). The presence of any one or more of these nuclear features increased the risk of carcinoma in subsequent thyroid resection. Papillary carcinomas predominated in excised FLUS cases with focal nuclear atypia whereas most FLUS with architectural atypia were adenomas or hyperplastic nodules on histological evaluation. BSRTC recommends that thyroid aspirates containing follicular cell nuclear and/or architectural atypia insufficient for a diagnosis of suspicious for follicular neoplasm, suspicious for malignancy or malignant be classified as FLUS. Our findings indicate that FLUS cases with focal nuclear atypia carry a risk for malignancy that is substantially higher than that assigned to FLUS and are best classified as suspicious. FLUS cases lacking these atypical nuclear features have a risk for malignancy that approximates the risk BSRTC has assigned to FLUS. Diagn. Cytopathol. 2014;42:18–22. © 2013 Wiley Periodicals, Inc.  相似文献   
62.
63.
Our objective was to determine the role of surface charge and wettability on early stage mineralization as well as bone cell adhesion and proliferation on polarized HAp surface. To estimate the surface wettability, contact angles were measured in water, simulated body fluid (SBF) and Dulbecco’s modified Eagle’s medium/nutrient mixture F-12 Ham (DMEM). Experimental results show that HAp surface wettability and surface energy can be tailored by inducing surface charge without introducing any volumetric effects in the material. Increasing the surface charge increased the wettability and also the energy of HAp surfaces in all tested media. A maximum surface energy of 49.47 ± 3.76 mJ/m2 was estimated for positively charged HAp surfaces polarized at 400 oC. The in vitro bioactivity of polarized HAp samples was evaluated by soaking in SBF and DMEM (cell media). Cell–materials interaction was studied by culturing with human fetal osteoblast cells (hFOB). In vitro results show that tailoring the combined effect of wettability and charge polarity on the HAp surface enable differential binding of inorganic ions (e.g., Ca2+, Cl?, Na+, HCO3? etc) and organic cell adhesive proteins (e.g., fibronectin, vitronectin etc) with different surface properties, which results in accelerated or decelerated mineralization as well as cell adhesion and proliferation on polarized HAp surface.  相似文献   
64.
Subcutaneous mycoses caused by the family Entomophthoraceae is very rare type of disease and is being reported sporadically from various Tropical countries including India. Here we report 8 cases of rhinoentomophthoromycosis caused by Conidiobolous coronatus and 7 cases of chronic subcutaneous phycomycosis caused by Basidiobolus ranarum. Cases were detected during a span of 9 years between 1991 to 1999, from 9 districts in and around Kolkata (Eastern India). Former type of lesions were detected among 20 to 65 age group of healthy individuals, predominantly males (7:1). In the latter type, male-female ratio was 2:5, and except for one all cases belonged to below 20 years age group of healthy individuals. Several cases were detected only after examination of repeat biopsy samples. With high degree of clinical suspicion, right approach is needed for laboratory confirmation of diagnosis.  相似文献   
65.
Electrically polarized bulk sintered hydroxyapatite (HAp) compacts have been shown to accelerate mineralization and bone tissue ingrowth in vivo. In this work, a comprehensive study has been carried out to investigate the influence of surface charge and polarity on in vitro bone cell adhesion, proliferation and differentiation on electrically polarized HAp-coated Ti. Uniform and crack free sol–gel derived HAp coatings of 20 ± 1.38 μm thickness were polarized by application of an external d.c. field of 2.0 kV cm?1 at 400 °C for 1h. In vitro bioactivity of polarized HAp coatings was evaluated by soaking in simulated body fluid, and bone cell–material interactions were studied by culturing with human fetal osteoblast cells (hFOB) for a maximum period of 11 days. Scanning electron microscopic observation showed that accelerated mineralization on negatively charged surfaces favored rapid cell attachment and faster tissue ingrowth over non-polarized HAp coating surfaces, while positive charge on HAp coating surfaces restricted apatite nucleation with limited cellular response. Immunochemistry and confocal microscopy confirmed that the cell adhesion and early stage differentiation were more pronounced on negatively charged coating surfaces as hFOB cells expressed higher vinculin and alkaline phosphatase proteins on negatively charged surface compared to cells grown on all other surfaces. Our results in this study are process independent and potentially applicable to any other commercially available coating techniques.  相似文献   
66.
Metallic biomaterials are widely used to restore the lost structure and functions of human bone. Due to the large number of joint replacements, there is a growing demand for new and improved orthopedic implants. More specifically, there is a need for novel load-bearing metallic implants with low effective modulus matching that of bone in order to reduce stress shielding and consequently increase the in vivo lifespan of the implant. In this study, we have fabricated porous Ti6Al4V alloy structures, using laser engineered net shaping (LENS?), to demonstrate that advanced manufacturing techniques such as LENS? can be used to fabricate low-modulus, tailored porosity implants with a wide variety of metals/alloys, where the porosity can be designed in areas based on the patient’s need to enhance biological fixation and achieve long-term in vivo stability. The effective modulus of Ti6Al4V alloy structures has been tailored between 7 and 60 GPa and porous Ti alloy structures containing 23–32 vol.% porosity showed modulus equivalent to human cortical bone. In vivo behavior of porous Ti6Al4V alloy samples in male Sprague–Dawley rats for 16 weeks demonstrated a significant increase in calcium within the implants, indicating excellent biological tissue ingrowth through interconnected porosity. In vivo results also showed that total amount of porosity plays an important role in tissue ingrowth.  相似文献   
67.
成年大鼠成骨细胞体外培养及细胞凋亡的观察   总被引:5,自引:0,他引:5  
目的 为研究骨重建过程中成骨细胞的关键作用 ,建立成年大鼠成骨细胞体外培养方法并进行细胞凋亡的观察。方法  1 5周龄SD大鼠 ,在无菌条件下取颅盖骨置于培养瓶中DMEM培养液 ,内含体积分数为 1 0 %的胎牛血清 (FCS) ,在体积分数为 5 %的CO2 、37℃孵箱内培养。按原位DNA末端标记 (TUNEL)检测试剂盒方法染色 ,以荧光显微镜观察凋亡。结果 经活体观察、ABC法Ⅰ型胶原染色和碱性酸酶染色 ,显示培养细胞为成骨细胞。结论 本实验建立了成年大鼠成骨细胞体外培养方法并进行细胞凋亡的观察  相似文献   
68.
目的观察仙荷降脂液对饲料所致高脂血症家兔血脂及血液流变性的影响。方法健康家兔随机分为对照组 (A组 ) ,高脂血症对照组 (B组 )和高脂血症治疗组 (C组 )。A组给予普通饲料 ,B组和C组均给予高脂饲料喂养 ,C组高脂喂养3周后每天加喂仙荷降脂液 ,于实验第0、21、42d分别测定血脂、血液流变学指标。结果C组用药后血清总胆固醇 (TC)、甘油三脂 (TG)、高密度脂蛋白胆固醇(HDL -C)均显著低于B组 (P<0.01) ;全血粘度 (10s-1)、血浆粘度、红细胞刚性指数 (REI)、血小板粘附率均明显降低(P<0.01 ,和P<0.05)。结论仙荷降脂液能降低高脂血症家兔血清TC、TG、HDL -C和改善血液流变性。  相似文献   
69.
Journal of Digital Imaging - Measurement of angles on foot radiographs is an important step in the&nbsp;evaluation of malalignment. The objective is to develop a CNN model to measure angles on...  相似文献   
70.

Introduction

The administration of pre and post-operative antibiotics for open reduction and internal fixation of facial fracture is the usual norm followed. Although the benefit of antibiotic has been established in the literature, the value of post-operative administration has been questioned and yet not extensively studied or investigated. There are rising concerns over the duration and undesired effects of antibiotics. The purpose of the study was to evaluate necessity and/or efficacy of post-operative antibiotics in the open reduction of zygomatic and mandibular fracture.

Methods

Sixty patients who underwent open reduction and internal fixation were divided into two groups for the trial. Ab group (30 patients) received pre, intra and post-operative antibiotics. Non-Ab group (30 patients) did not receive post-operative antibiotics though pre and intra-operative antibiotics were administered. Patients were evaluated for post-op infection at the end of 1st and 3rd week after operation.

Results

Among 60 patients, 2 patients (1 from Ab group and 1 from non-Ab group) were infected; so statistically no significant difference in result was obtained (Fisher’s exact test, P value = 1).

Conclusion

In this trial, the use of post-operative antibiotics in the open reduction and internal fixation of facial fracture was shown to confer no benefit/efficacy in reducing the chances of infection.  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