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   1574篇
  免费   146篇
  国内免费   88篇
耳鼻咽喉   30篇
儿科学   43篇
妇产科学   19篇
基础医学   154篇
口腔科学   30篇
临床医学   196篇
内科学   331篇
皮肤病学   11篇
神经病学   84篇
特种医学   32篇
外科学   355篇
综合类   36篇
预防医学   89篇
眼科学   62篇
药学   137篇
中国医学   6篇
肿瘤学   193篇
  2023年   8篇
  2022年   18篇
  2021年   34篇
  2020年   23篇
  2019年   42篇
  2018年   37篇
  2017年   41篇
  2016年   36篇
  2015年   60篇
  2014年   65篇
  2013年   70篇
  2012年   98篇
  2011年   122篇
  2010年   63篇
  2009年   56篇
  2008年   79篇
  2007年   126篇
  2006年   103篇
  2005年   101篇
  2004年   84篇
  2003年   84篇
  2002年   55篇
  2001年   54篇
  2000年   37篇
  1999年   31篇
  1998年   10篇
  1997年   21篇
  1996年   21篇
  1995年   12篇
  1994年   13篇
  1993年   11篇
  1992年   26篇
  1991年   21篇
  1990年   23篇
  1989年   13篇
  1988年   11篇
  1987年   6篇
  1986年   11篇
  1985年   9篇
  1983年   7篇
  1981年   4篇
  1980年   5篇
  1979年   5篇
  1978年   4篇
  1977年   7篇
  1976年   7篇
  1975年   5篇
  1974年   7篇
  1973年   4篇
  1972年   6篇
排序方式: 共有1808条查询结果,搜索用时 15 毫秒
81.
目的:观察白藜芦醇对一次性力竭游泳大鼠肝脏组织的作用及发挥作用的最佳口服剂量。方法:实验于2006-05/07在成都体育学院运动医学系动物实验室完成。①实验分组:选取雄性SD大鼠70只,随机分为7组,每组10只,分别为安静对照组,运动对照组,运动 15mg/kg白藜芦醇组,运动 50mg/kg白藜芦醇组,运动 100mg/kg白藜芦醇组,运动 200mg/kg白藜芦醇组,运动 300mg/kg白藜芦醇组。②实验干预:不同剂量白藜芦醇组每天灌胃15,50,100,200,300mg/kg白藜芦醇,安静对照组和运动对照组分别灌胃相同体积的溶媒(二甲亚砜 生理盐水),连续5周。末次给予实验用样品1h后,各运动组每只鼠尾跟部负荷3%体质量铅皮,置于水深50cm、水温(31±1)℃游泳槽中游泳。游泳力竭后即刻,股动脉取血并迅速取出肝组织。③指标检测:赖氏比色法测定血清中谷丙转氨酶活性;邻苯三酚自氧化法测定肝组织超氧化物歧化酶活性;硫代巴比妥酸法测定肝组织丙二醛含量。结果:纳入动物70只,均进入结果分析。①血清谷丙转氨酶活性和肝组织中丙二醛含量:运动对照组显著高于安静对照组,不同剂量白藜芦醇组低于运动对照组(P<0.05或P<0.01)。运动 100,200,300mg/kg白藜芦醇组低于运动 15,50mg/kg白藜芦醇组[谷丙转氨酶活性:(972.36±121.86),(944.36±105.35),(888.34±88.68),(1773.52±89.35),(1377.78±27.01)nkat/L,P<0.01;丙二醛含量:(7.90±2.56),(7.69±3.69),(7.13±2.62),(19.90±2.21),(12.16±1.78)μmol/g,P<0.05]。100,200,300mg/kg白藜芦醇组间差异无显著性。②肝脏组织中超氧化物歧化酶活性:运动对照组显著低于安静对照组,不同剂量白藜芦醇组高于运动对照组(P<0.05或P<0.01)。运动 100,200,300mg/kg白藜芦醇组高于15,50mg/kg白藜芦醇组[(2325.80±163.37),(2379.14±121.86),(2447.16±89.18),(1096.05±120.19),(1514.64±28.17)μkat/g,P<0.01]。结论:①白藜芦醇对力竭性运动大鼠肝脏组织具有保护作用。②100,200,300mg/kg白藜芦醇对肝脏组织发挥保护作用效果优于15,50mg/kg,建议使用100mg/kg白藜芦醇就能达到理想效果。  相似文献   
82.
Objective:  The purpose of the present study was to build a database of reference ranges of fetal nasal bone length (NBL) in a Chinese population. The accuracy rate of detecting Down syndrome was also analyzed using fetal NBL as a marker.
Methods:  The control group of fetuses included 342 normal singleton pregnancies with no chromosomal or congenital anomalies. The present study was a cross-section study and the control group was used to construct percentile values of NBL from 13 to 29 gestational weeks of age. Two-dimensional ultrasonography was used for the nasal bone studies. Measurements of NBL were collected and each fetus contributed a single value to the reference sample. During the study period, 14 fetuses with Down syndrome were examined. Measurement of fetal NBL was made during amniocentesis, with gestational age ranging from 13 to 19 weeks.
Results:  From 342 normal fetuses with gestational age ranging from 13 to 29 weeks, reference ranges of NBL were constructed. The reference ranges were constructed from the 100(1 − p)% reference range:     , where Ŷ  = 25 − exp(3.58 − 0.044 ×  t  + 0.0006 ×  t 2), with Ŷ being the fitted mean of regression model and t being gestational age (weeks). Using fetal NBL, the regression model was Pr (Down syndrome) = exp( W )/[1 + exp( W )], where W  = 0.62–4.80 × NBL (multiples of the median) in predicting Down syndrome. Fetal NBL was found to have a sensitivity and specificity of 0.78 and 0.78, respectively, in predicting Down syndrome in the second trimester of pregnancy.
Conclusions:  Fetal NBL measurement can provide a simple and useful algorithm to predict Down syndrome during the second trimester of pregnancy.  相似文献   
83.

Background

Current measures for breast cancer prevention and options for treatment adopted in Hong Kong are mainly based on research data and clinical evidence from overseas. It is essential to establish a cancer-specific registry to monitor the status of breast cancer in Hong Kong.

Objectives

We summarized the current status of breast cancer in Hong Kong based on the data collected from Hong Kong Breast Cancer Registry (HKBCR).

Methods

Prevalent and newly diagnosed breast cancers (including in situ and invasive breast cancers) were registered in the HKBCR. Information on patient demographics, risk factors, medical information, and survival were analyzed and reported in this study.

Results

Data of 2,330 breast cancer patients were analyzed. We observed an earlier median age at diagnosis in Hong Kong than those reported in other countries. Distribution of cancer stage was: stage 0 (11.4%), stage I (31.4%), stage II (41%), stage III (12.5%), stage IV (0.8%), and unclassified (2.9%). The percentages of patients who received surgery, chemotherapy, radiation therapy, and endocrine therapy were 98.7, 67.9, 64.8, and 64.1%, respectively. At a median follow-up of 1.2?years, locoregional recurrence was recorded at 2%, distant recurrence at 2.8%, and breast-cancer–related mortality at 0.3%.

Conclusions

The HKBCR serves as a surveillance program to monitor disease and treatment patterns. It is pivotal to support research for more effective breast cancer prevention and treatment strategies in Hong Kong.  相似文献   
84.
The present study retrospectively reviews our experience in 40 cases of vestibular schwannoma, operated between the years 1995 and 2002. All the patients underwent tumour resection either in sitting or in the Park bench position via the suboccipital retromastoid route. The position of the patient was selected arbitrarily. Precordial Doppler echocardiography was used to monitor air embolism. Operative results, including the size of the tumour, completeness of resection, anatomical and functional preservation of the facial nerve, operative complications and mortality were analysed and compared in these two operative positions. There was no statistically significant difference in terms of surgical results between these two groups.   相似文献   
85.
经肛门内镜显微手术切除直肠肿瘤   总被引:14,自引:3,他引:14  
目的评价经肛门内镜显微手术(TEM)切除直肠绒毛状腺瘤和早期直肠癌的应用效果。方法分析我院总结1995年11月至2001年12月27例TEM手术的临床资料。结果本组患者肿瘤直径中位值2.5cm,肿瘤下缘与齿状线距离(8.9±3.4)cm,肿瘤侵犯直肠周径范围(35.7±17.5)%。平均手术时间(109±46)min。平均住院日4.5d。无围手术期死亡。手术并发症有尿潴留、暂时性大便失禁和慢性阻塞性肺病(COPD)复发。术中2例切穿至腹腔,即刻内镜下修补成功。切缘100%瘤细胞阴性。病理示直肠绒毛状腺瘤14例、直肠腺癌13例,后者包括pTis2例,pT16例和pT25例。直肠癌腔内超声肿瘤T分期符合率为84.6%。5例pT2中2例中转前切除术,1例接受术后放疗,2例无附加任何治疗。平均随访18个月,所有病例无局部复发。死亡2例,但无复发迹象。结论TEM易行且安全,是直肠绒毛状腺瘤和部分T1直肠癌的治愈性手术,也可作为T2直肠癌的姑息性治疗手段。  相似文献   
86.
目的探讨经肛门内镜显微手术(transanal endoscopicmic rosurgery,TEM)治疗直肠绒毛状腺瘤和早期直肠癌的疗效。方法1995年11月~2003年12月,我院行TEM治疗直肠肿瘤31例。全麻下根据肿瘤位置选择合适的体位,经肛门插入特殊的手术直肠镜,保持CO2充气状态,在立体视镜和腔镜系统下,采用针形电刀或5mm超声刀将直肠肿瘤完整切除(黏膜下或全层切除),手术创口在腔内连续缝合。结果31例直肠肿瘤均获完整切除,切缘均阴性。手术时间45~220min,平均95min;术中出血量0~180ml,平均40ml。手术并发症:暂时性排气失控2例,急性尿潴留1例,慢性阻塞性气道疾病急性发作1例,因服用阿斯匹林而出现继发性出血1例。术后病理分期:pT0期16例,pTis期2例,pT1期7例,pT2和pT3期各3例。31例随访2~92个月,平均23个月,肿瘤无原位复发。结论TEM是治疗直肠绒毛状腺瘤和早期直肠癌的一种安全、有效的微创手术方法。  相似文献   
87.
We present a case of histologically confirmed lipomatous meningioma, the first to our knowledge reported in Hong Kong. A 75‐year‐old woman presented to us with on and off dizziness for 1 month. Computed tomography (CT) of the brain showed an extra‐axial mass lesion containing fat and solid enhancing foci at her right frontal region. The definitive diagnosis could be made preoperatively. Postoperative histological examination of the tumour revealed the diagnosis of lipomatous meningioma. We have reviewed the literature and discussed the diagnostic clues, clinical presentation and pathology of this rare tumour.  相似文献   
88.
Background and Aims: In the management of peptic ulcer bleeding, the benefits of second‐look endoscopic treatment with thermal coagulation or injections in controlling recurrent bleeding is unsure. This study set out to compare efficacy of routine second‐look endoscopy with treatment using either thermal coagulation or injections versus single endoscopy by pooling data from published work. Methods: Full publications in the English‐language published work as well as abstracts in major international conferences were searched over the past 10 years, and six trials fulfilling the search criteria were found. Outcome measurements included: (i) recurrent bleeding; (ii) requirement of surgical intervention; and (iii) mortality. We examined heterogeneity of trials and pooled the effects by meta‐analysis. The quality of studies was graded according to the prospective randomization, methods of patient allocation, the list of exclusion criteria, outcome definitions and the predefined salvage procedures for uncontrolled bleeding. Results: Among 998 patients recruited in these five randomized trials, 119 received routine second‐look endoscopy with thermal coagulation, and 374 received second‐look with endoscopic injection and 505 had single endoscopic therapy. Less recurrent bleeding was reported after thermal coagulation (4.2%) than single endoscopy (15.7%) (relative risk [RR] = 0.29; 95% confidence interval [CI] = 0.11–0.73), but no reduction was reported for the requirement of surgical intervention and all‐cause mortality. Injection therapy did not reduce re‐bleeding (17.6%) when compared to single endoscopy (20.8%; RR = 0.85; 95% CI = 0.63–1.14), requirement for surgery and mortality. Conclusion: Routine second‐look endoscopy with thermal coagulation, but not injection therapy, reduced recurrent peptic ulcer bleeding. There is no proven benefit in reducing surgical intervention and overall mortality.  相似文献   
89.
We identified a novel zebrafish mutant that has wavy‐notochord phenotypes, such as severely twisted notochord and posterior malformations, but has normal melanocytes. Histological evidences showed that proliferating vacuolar cells extended their growth to the muscle region, and consequently caused the wavy‐notochord phenotypes. Interestingly, those malformations can be greatly reversed by exposure with copper, suggesting that copper plays an important role on wavy‐notochord phenotypes. In addition, after long‐term copper exposure, the surviving larvae derived from wavy‐notochord mutants displayed bone malformations, such as twisted axial skeleton and osteophyte. These phenotypic changes and molecular evidences of wavy‐notochord mutants are highly similar to those embryos whose lysyl oxidases activities have been inactivated. Taken together, we propose that (i) the putative mutated genes of this wavy‐notochord mutant might be highly associated with the lysyl oxidase genes in zebrafish; and (ii) this fish model is an effective tool for monitoring copper pollution of water from natural resources. © 2009 Wiley Periodicals, Inc. Environ Toxicol 26: 103–109, 2011.  相似文献   
90.
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