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   1210篇
  免费   99篇
  国内免费   19篇
耳鼻咽喉   3篇
儿科学   82篇
妇产科学   9篇
基础医学   117篇
口腔科学   26篇
临床医学   95篇
内科学   243篇
皮肤病学   27篇
神经病学   24篇
特种医学   132篇
外科学   139篇
综合类   152篇
预防医学   83篇
眼科学   9篇
药学   67篇
中国医学   41篇
肿瘤学   79篇
  2023年   8篇
  2022年   17篇
  2021年   25篇
  2020年   20篇
  2019年   16篇
  2018年   25篇
  2017年   21篇
  2016年   22篇
  2015年   29篇
  2014年   47篇
  2013年   42篇
  2012年   50篇
  2011年   47篇
  2010年   76篇
  2009年   63篇
  2008年   28篇
  2007年   34篇
  2006年   45篇
  2005年   30篇
  2004年   27篇
  2003年   26篇
  2002年   17篇
  2001年   19篇
  2000年   12篇
  1999年   28篇
  1998年   50篇
  1997年   60篇
  1996年   52篇
  1995年   40篇
  1994年   35篇
  1993年   35篇
  1992年   12篇
  1991年   7篇
  1990年   11篇
  1989年   27篇
  1988年   33篇
  1987年   22篇
  1986年   28篇
  1985年   26篇
  1984年   28篇
  1983年   12篇
  1982年   20篇
  1981年   13篇
  1980年   11篇
  1979年   3篇
  1977年   6篇
  1976年   6篇
  1975年   2篇
  1958年   4篇
  1957年   2篇
排序方式: 共有1328条查询结果,搜索用时 0 毫秒
111.
目的 建立大鼠血浆中栀蒡热毒平方有效组分中栀子苷、牛蒡子苷和黄芩苷的HPLC血药浓度测定方法.方法 血浆样品采用甲醇-乙腈(1∶ 1)沉淀蛋白,HPLC测定血药浓度.色谱柱为Diamonsil C18柱(4.6 mm×150 mm, 5 μm),流动相乙腈-0.2%磷酸水梯度洗脱,流速1.0 mL/min,检测波长238 nm和278 nm.结果 各成分的最低检测浓度(S/N>3)在0.23~0.32 mg/L,平均回收率均在85%以上,日内、日间精密度及稳定性的RSD均小于10%.结论 该方法简便、准确,可作为栀蒡热毒平方血药浓度定量分析方法.  相似文献   
112.

INTRODUCTION

Published colorectal cancer surgery data suggest no role for the analysis of the anastomotic doughnuts following anterior resection. The usefulness of routine histological analysis of the upper gastrointestinal doughnut is not clear. Our study assessed the impact of cancer involvement of the doughnut on clinical practice. Factors associated with doughnut involvement and the effect on patients'' survival were also analysed.

PATIENTS AND METHODS

The clinicopathological details of 462 patients who underwent potentially curative oesophagogastrectomy for cancer with a stapled anastomosis between 1994 and 2006 in two specialist centres were retrospectively analysed. Univariate, multivariate and survival analyses were carried out.

RESULTS

Approximately 5% of doughnuts (22 of 462) were histologically involved with cancer. Microscopic involvement of the proximal resection margin, local lymph node metastasis and lymphatic invasion within the main resected specimen were independently associated with doughnut involvement (all P < 0.05). However, these three factors taken together failed to predict doughnut involvement. Doughnut involvement was an independent adverse prognostic factor for overall survival (P = 0.0013).

CONCLUSIONS

In contrast to findings in colorectal surgery, doughnut involvement with cancer appears to have useful prognostic information following oesophagogastrectomy. Routine histological analysis of upper gastrointestinal doughnuts is justified. Doughnut involvement could potentially strengthen the indications for adjuvant therapy in the future.  相似文献   
113.

Introduction

Breast gangrene has been reported as a complication following puerperal sepsis, breast surgery, nipple piercings, warfarin toxicity, etc. We report a case of primary breast gangrene in an HIV-positive individual which, to the best of our knowledge, is the first of its kind.

Case report

A 40-year-old previously healthy woman presented with fulminating left breast gangrene. She was detected to be HIV positive. Mastectomy was performed. The detailed management of the condition is discussed.

Conclusion

Severe necrotising infections may be initial manifestations of HIV infection and patients with such infections should be screened for HIV.  相似文献   
114.
子宫结合带(JZ)是MRI上显示的子宫壁正常结构,JZ在MRI上呈低信号。妊娠期以外的子宫结合带是依赖雌激素的周期性调控来控制子宫的收缩运动的,除此之外,许多生物因子都参与了JZ的调节,如CX43、干扰素因子IFNγ、细胞活素和生长因子等。JZ与子宫肌瘤、子宫内膜异位症、子宫腺肌症、妊娠期并发症、不孕、胚胎植入等的发生均有关,其相关研究现在主要聚集在MRI方面的研究,本文综述了子宫结合带的调节因素及相关疾病。  相似文献   
115.
BACKGROUND: Women exhibit greater liver damage than men after chronic alcohol consumption. Similar findings are reported in animal models. Here, we determined whether differential liver injury occurred in male and female rats after feeding these animals liquid diets containing either ethanol or isocaloric dextrose with fish oil as the sole source of lipid. METHODS: Control and ethanol liquid diets containing fish oil were pair-fed to male and female rats for 8 weeks. Liver damage was evaluated by triglyceride accumulation, lipid peroxide formation, serum transaminases, histological evaluation, and the activities of selected lysosomal and hepatoprotective enzymes. RESULTS: Fatty liver was detected after ethanol feeding in both genders, but in female rats, triglyceride levels were 60% higher, lipid peroxides were 2-fold higher, and inflammatory cells were more evident than in males. A 2-fold elevation of cathepsin B in hepatic cytosol fractions, indicating lysosomal leakage, was detected in ethanol-fed female rats but no such elevation was observed in males. The basal activity of the hepatoprotective enzyme, betaine-homocysteine methyltransferase was 4-fold higher in livers of control male rats than females, and the enzyme activity was further elevated in ethanol-fed male rats but not in females. CONCLUSIONS: Thus, female rats given ethanol in a diet containing fish oil exhibited more severe liver damage than males. We propose that this difference results, in part, from a greater tendency by females to accumulate hepatic fat, thereby enhancing the potential for oxidative stress, which in turn leads to hepatic inflammation. In addition, our findings indicate that female rats have a higher susceptibility to liver damage because of a reduced capacity for hepatoprotection.  相似文献   
116.

Background  

Within the last decade there has been a growth in the call-centre industry in the UK, with a growing awareness of the voice as an important tool for successful communication. Occupational voice problems such as occupational dysphonia, in a business which relies on healthy, effective voice as the primary professional communication tool, may threaten working ability and occupational health and safety of workers. While previous studies of telephone call-agents have reported a range of voice symptoms and functional vocal health problems, there have been no studies investigating the use and impact of vocal performance in the communication industry within the UK. This study aims to address a significant gap in the evidence-base of occupational health and safety research. The objectives of the study are: 1. to investigate the work context and vocal communication demands for call-agents; 2. to evaluate call-agents' vocal health, awareness and performance; and 3. to identify key risks and training needs for employees and employers within call-centres.  相似文献   
117.
目的对用于评价西安城区居民膳食营养状况的西安食物频率问卷(FFQ)的重现性和准确性进行食物组的研究。方法在西安城区随机抽取出125名50~80岁当地居民,共完成6轮的食物摄入情况的调查,其中4轮24小时膳食回顾调查(24HDRs)的结果作为参考,通过第一轮FFQ结果与第二轮FFQ以及4轮24HDRs结果之间的比较分别进行FFQ的重现性和准确性研究。结果各个食物组在两轮FFQ间的Spearman相关系数在0.38(糕点类)~0.74(茶类)。第二轮FFQ与4轮24HDRs均值间的相关系数在0.12~0.74之间,经过个体内方差校正后,相关系数均有所提高。结论西安食物频率问卷可以相对准确、可靠地评价西安城区50岁以上居民的膳食营养状况。  相似文献   
118.
直视下尿道内切开术的再认识   总被引:7,自引:0,他引:7  
目的:观察直视下尿道内切开术(DVIU)的长期疗效,重新评价DVIU的临床应用价值。方法:回顾性分析2003年1月~2007年1月收治的65例尿道狭窄或闭锁患者行DVIU及术后随访的临床资料:狭窄长度0.5~2.0cm,平均1.2cm。其中≤1.0cm者25例,1.1~2.0cm者40例。30例行尿道超声检查测量尿道瘢痕厚度,其中瘢痕厚度≤1cm者10例,〉1cm者20例,瘢痕长度和厚度均≤1cm者9例。结果:65例共行DVIU72例次,72例次内切开手术均获得成功。63例获得随访,随访时间24~60个月,平均40.5个月。48例(76.2%)因狭窄复发而最终接受开放手术。尿道超声显示瘢痕厚度≤1cm的10例中,只有1例接受手术;瘢痕厚度〉1cm的20例中,18例接受手术;瘢痕长度和厚度均≤1cm的9例均未行手术。结论:DVIU适合于狭窄段和瘢痕厚度均〈1cm的患者,切开次数以1次为宜,手术疗效与严格掌握适应证密切相关。  相似文献   
119.
目的:探讨尿道狭窄患者围手术期尿液TGF-β1浓度变化情况以及影响该浓度的相关因素.方法:使用ELISA试剂盒对29例尿道狭窄患者术前1个月及术后1个月尿液中TGF-β1进行测定及记录.同期取泌尿系统其他手术的14例患者作为对照组,测定其术后1个月尿液中TGF-β1浓度.结果:检测结果显示实验组在接受手术治疗后尿液中TGF-β1含最较对照组有显著增高(P<0.05).同时实验组患者术前和术后尿液TGF-β1浓度也存在明显差异(P<0.05).在相关性因素的分析中,前尿道狭窄患者术后尿液中TGF-β1含量的变化幅度较后尿道狭窄患者更为显著(P<0.05),同时采用自体组织替代技术较传统端端吻合技术以及内镜切开技术更能引起尿液中TGF-β1的明显变化(P<0.05).但年龄、既往手术次数均未能引起患者术后TGF-β1的变化.结论:狭窄部位、手术方式都与患者尿液中 TGF-β1的含量存在一定的联系,而年龄及既往手术史等因素未发现与患者体内TGF-β1含量有较大的联系.  相似文献   
120.
Ko V  Nanji S  Tambouret RH  Wilbur DC 《Cancer》2007,111(2):67-73
BACKGROUND: Inappropriate use of the category of atypical squamous cells of undetermined significance (ASCUS) can result in overtreatment or undertreatment of patients, which may decrease the cost effectiveness of screening. Quality assurance tools, such as the ASCUS to squamous intraepithelial lesion ratio (ASCUS:SIL) and case review, are imperfect. High-risk HPV (hrHPV) testing is an objective test for a known viral carcinogen, and hrHPV may be more useful in monitoring the quality of ASCUS interpretations. METHODS: hrHPV rates for cytologic diagnoses and patient age groups were calculated for a 2-year period. All hrHPV results for ASCUS and SIL over a 17-month period were analyzed by patient age group, over time, and by individual cytopathologist to compare hrHPV rates with the corresponding ASCUS:SIL. RESULTS: The hrHPV positive rate for SIL was >90%, and it was 32.6% for ASCUS. Stratification by patient age showed that approximately 50% of patients younger than 30 years and older than 70 years of age were hrHPV positive, whereas other patients had a lower rate ranging from 14% to 34%. The overall ASCUS:SIL was 1.42, and the overall hrHPV positive rate was 39.9%. Over time and by individual cytopathologist, the hrHPV rate performed similarly to the ASCUS:SIL. The analysis by patient age showed a high statistical correlation (R(2) = 0.9772) between the 2 methods. CONCLUSIONS: Despite differences between these techniques, the hrHPV rate closely recapitulates the ASCUS:SIL. When used together, the 2 methods can complement each other. The desirable hrHPV-positive range appears to be 40% to 50%; however, this may vary based on the patient population. The hrHPV rate is as quick and cost effective as determining the ASCUS:SIL.  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