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   8739篇
  免费   712篇
  国内免费   59篇
耳鼻咽喉   63篇
儿科学   307篇
妇产科学   301篇
基础医学   1151篇
口腔科学   273篇
临床医学   836篇
内科学   1807篇
皮肤病学   71篇
神经病学   536篇
特种医学   293篇
外科学   1470篇
综合类   168篇
一般理论   10篇
预防医学   422篇
眼科学   339篇
药学   472篇
中国医学   31篇
肿瘤学   960篇
  2024年   12篇
  2023年   58篇
  2022年   74篇
  2021年   214篇
  2020年   145篇
  2019年   189篇
  2018年   250篇
  2017年   133篇
  2016年   189篇
  2015年   241篇
  2014年   331篇
  2013年   349篇
  2012年   544篇
  2011年   622篇
  2010年   383篇
  2009年   358篇
  2008年   544篇
  2007年   591篇
  2006年   561篇
  2005年   509篇
  2004年   456篇
  2003年   408篇
  2002年   312篇
  2001年   302篇
  2000年   257篇
  1999年   207篇
  1998年   70篇
  1997年   67篇
  1996年   55篇
  1995年   41篇
  1994年   49篇
  1993年   41篇
  1992年   111篇
  1991年   98篇
  1990年   99篇
  1989年   95篇
  1988年   67篇
  1987年   69篇
  1986年   61篇
  1985年   55篇
  1984年   41篇
  1983年   38篇
  1982年   27篇
  1981年   30篇
  1980年   23篇
  1979年   23篇
  1978年   17篇
  1977年   24篇
  1976年   15篇
  1975年   13篇
排序方式: 共有9510条查询结果,搜索用时 12 毫秒
91.
Imaging findings in hippocampal sclerosis: correlation with pathology   总被引:15,自引:0,他引:15  
We evaluated the ability of preoperative radiologic imaging to detect hippocampal sclerosis in 31 patients who underwent surgery for intractable epilepsy. Hippocampal sclerosis is commonly associated with surgically treatable temporal lobe epilepsy. It is pathologically described as neuronal cell loss with associated gliosis in the hippocampus. While previous reports have correlated imaging results with clinical or qualitative histologic findings, this study used quantitative pathologic criteria (neuronal cell density) to diagnosis hippocampal sclerosis. We focused our study on the 11 patients with cryptogenic temporal lobe epilepsy. Of these, nine had hippocampal sclerosis by pathologic criteria. MR findings included unilateral hippocampal atrophy, an increased signal in the hippocampus on long TR scans, and atrophy in the adjacent white matter and temporal lobe. Hippocampal atrophy was most frequently seen in the red nucleus plane on coronal scans, corresponding to the body of the hippocampus. We also compared hippocampal size on MR with neuronal density in surgical specimens of the 11 patients with cryptogenic temporal lobe epilepsy. A statistically significant correlation was found between MR size and neuronal density in CA3 and CA4 of the cornu ammonis and the granular cell layer of the hippocampus. Since temporal lobectomy eliminated seizures in seven of nine patients with hippocampal sclerosis, preoperative diagnosis by MR has important therapeutic consequences.  相似文献   
92.
Immunoreactive prostaglandin (PG) E2 was released into the ambient medium in a dose dependent fashion when either hydroxyapatite (HA) or calcium pyrophosphate dihydrate (CPPD) crystals were added to canine synovial fibroblasts in tissue culture. PGE2 release peaked 6 to 9 hours after HA or CPPD crystals were added in the presence of serum but at 24 hours if they were added in the presence of lactalbumin hydrolysate. PGE2 release correlated with crystal endocytosis estimated qualitatively by serial phase contrast microscopy and time lapse photography. As postulated previously by others for monosodium urate crystals, prostaglandin production by synovial cells may also be related to the pathogenesis of the destructive arthropathies associated with HA or CPPD crystals.  相似文献   
93.
94.
95.

Summary

Vertebral fractures are the most common osteoporotic fractures. Data on the vertebral fracture risk in Asia remain sparse. This study observed that Hong Kong Chinese and Japanese populations have a less dramatic increase in hip fracture rates associated with age than Caucasians, but the vertebral fracture rates were higher, resulting in a high vertebral-to-hip fracture ratio. As a result, estimation of the absolute fracture risk for Asians may need to be readjusted for the higher clinical vertebral fracture rate.

Introduction

Vertebral fractures are the most common osteoporotic fractures. Data on the vertebral fracture risk in Asia remain sparse. The aim of this study was to report the incidence of clinical vertebral fractures among the Chinese and to compare the vertebral-to-hip fracture risk to other ethnic groups.

Methods

Four thousand, three hundred eighty-six community-dwelling Southern Chinese subjects (2,302 women and 1,810 men) aged 50 or above were recruited in the Hong Kong Osteoporosis Study since 1995. Baseline demographic characteristics and medical history were obtained. Subjects were followed annually for fracture outcomes with a structured questionnaire and verified by the computerized patient information system of the Hospital Authority of the Hong Kong Government. Only non-traumatic incident hip fractures and clinical vertebral fractures that received medical attention were included in the analysis. The incidence rates of clinical vertebral fractures and hip fractures were determined and compared to the published data of Swedish Caucasian and Japanese populations.

Results

The mean age at baseline was 62?±?8.2?years for women and 68?±?10.3?years for men. The average duration of follow-up was 4.0?±?2.8 (range, 1 to 14) years for a total of 14,733 person-years for the whole cohort. The incidence rate for vertebral fracture was 194/100,000 person-years in men and 508/100,000 person-years in women, respectively. For subjects above the age of 65, the clinical vertebral fracture and hip fracture rates were 299/100,000 and 332/100,000 person-years, respectively, in men, and 594/100,000 and 379/100,000 person-years, respectively, in women. Hong Kong Chinese and Japanese populations have a less dramatic increase in hip fracture rates associated with age than Caucasians. At the age of 65 or above, the hip fracture rates for Asian (Hong Kong Chinese and Japanese) men and women were less than half of that in Caucasians, but the vertebral fracture rate was higher in Asians, resulting in a high vertebral-to-hip fracture ratio.

Conclusions

The incidences of vertebral and hip fractures, as well as the vertebral-to-hip fracture ratios vary in Asians and Caucasians. Estimation of the absolute fracture risk for Asians may need to be readjusted for the higher clinical vertebral fracture rate.  相似文献   
96.

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   
97.
目的:观察遗传性骨软骨瘤软骨细胞的生物学特性。方法:采用透射电镜、细胞培养等方法观察肿瘤软骨细胞形态特征;同时观察肿瘤软骨细胞的增殖、贴附能力,与正常人关节软骨细胞做对照。结果:透射电镜(TEM)发现肿瘤软骨细胞膜附近含有大量的微丝结构,集结成束,与细胞突起有关;体外单层培养发现肿瘤软骨细胞突起增多,细胞呈现星形;骨软骨瘤软骨细胞的增殖与贴附能力随着传代的增加减慢和减低,传4代细胞增殖能力和贴附能力均与肿瘤原代细胞及正常关节软骨细胞具有明显差别(P<0.1)。结论:骨软骨瘤软骨细胞虽然与正常软骨细胞大体相似,但生物学特性存在明显区别:细胞形态改变,微丝增加,细胞增殖与贴附能力等均不同于正常软骨细胞。  相似文献   
98.
Hemodialysis vascular access dysfunction is a major cause of morbidity and hospitalization in the hemodialysis population. The major cause of hemodialysis vascular access dysfunction is venous stenosis as a result of neointimal hyperplasia. Despite the magnitude of the clinical problem, however, there has been a paucity of novel therapeutic interventions in this field. This is in marked contrast to a recent plethora of targeted interventions for the treatment of arterial neointimal hyperplasia after coronary angioplasty. The reasons for this are two-fold. First there has been a relative lack of cellular and molecular research that focuses on venous neointimal hyperplasia in the specific setting of hemodialysis vascular access. Second, there have been inadequate efforts by the nephrology community to translate the recent advances in molecular and interventional cardiology into therapies for hemodialysis vascular access. This review therefore (1) briefly examines the different forms of hemodialysis vascular access that are available, (2) describes the pathology and pathogenesis of hemodialysis vascular access dysfunction in both polytetrafluoroethylene grafts and native arteriovenous fistulae, (3) reviews recent concepts about the pathogenesis of vascular stenosis that could potentially be applied in the setting of hemodialysis vascular access dysfunction, (4) summarizes novel experimental and clinical therapies that could potentially be used in the setting of hemodialysis vascular access dysfunction, and, finally, (5) offers some broad guidelines for future innovative translational and clinical research in this area that hopefully will reduce the huge clinical morbidity and economic costs that are associated with this condition.  相似文献   
99.
100.
BACKGROUND: Studies have shown that 27% to 38% of girls with adolescent idiopathic scoliosis have systemic osteopenia. The aim of this study was to investigate whether osteopenia could serve as one of the important prognostic factors in predicting curve progression. METHODS: A prospective study was performed in 324 adolescent girls with adolescent idiopathic scoliosis who had a mean age of thirteen and a half years. Bone mineral density of the spine and both hips was measured at the time of the clinical diagnosis of scoliosis. All patients were followed longitudinally until skeletal maturity or until the curve had progressed > or =6 degrees . The univariate chi-square test and stepwise logistic regression were used to predict the prevalence of curve progression, and a receiver operating characteristic curve was plotted. RESULTS: The overall prevalence of curve progression was 50%. The prevalence of osteopenia at the spine and hips was 27.5% and 23.1%, respectively. A larger initial Cobb angle (odds ratio = 4.6), a lower Risser grade (odds ratio = 4.7), premenarchal status (odds ratio = 2.5), osteopenia in the femoral neck of the hip on the side of the concavity (odds ratio = 2.3), and a younger age at the time of diagnosis (odds ratio = 2.1) were identified as risk factors in predicting curve progression. A predictive model was established, and the area under the receiver operating characteristic curve of the model was 0.80 (p < 0.01). CONCLUSION: Osteopenia may be an important risk factor in curve progression. The measurement of bone mineral density at the time of diagnosis may serve as an additional objective measurement in predicting curve progression in adolescent idiopathic scoliosis. The bone mineral density-inclusive predictive model may be used in treatment planning for patients with adolescent idiopathic scoliosis who are at high risk of curve progression.  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