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   3256篇
  免费   162篇
  国内免费   15篇
耳鼻咽喉   49篇
儿科学   61篇
妇产科学   87篇
基础医学   614篇
口腔科学   113篇
临床医学   246篇
内科学   725篇
皮肤病学   95篇
神经病学   250篇
特种医学   101篇
外科学   335篇
综合类   20篇
一般理论   1篇
预防医学   250篇
眼科学   46篇
药学   228篇
中国医学   25篇
肿瘤学   187篇
  2023年   26篇
  2022年   33篇
  2021年   80篇
  2020年   57篇
  2019年   79篇
  2018年   119篇
  2017年   91篇
  2016年   86篇
  2015年   101篇
  2014年   122篇
  2013年   171篇
  2012年   268篇
  2011年   289篇
  2010年   144篇
  2009年   84篇
  2008年   175篇
  2007年   197篇
  2006年   184篇
  2005年   181篇
  2004年   157篇
  2003年   166篇
  2002年   159篇
  2001年   27篇
  2000年   33篇
  1999年   27篇
  1997年   8篇
  1996年   8篇
  1992年   14篇
  1991年   21篇
  1990年   8篇
  1989年   18篇
  1988年   21篇
  1987年   15篇
  1986年   16篇
  1985年   25篇
  1984年   20篇
  1983年   13篇
  1981年   6篇
  1979年   8篇
  1978年   11篇
  1977年   8篇
  1976年   12篇
  1974年   11篇
  1973年   9篇
  1972年   7篇
  1971年   15篇
  1970年   13篇
  1969年   7篇
  1968年   7篇
  1966年   9篇
排序方式: 共有3433条查询结果,搜索用时 0 毫秒
71.
72.
73.
BACKGROUND: It has been suggested that genes related to Amerindian ancestry account for the high prevalence of gallstone disease (GD) observed in Mexican-Americans. The HLA-B39 is an allele found in higher frequency in Amerindians whereas HLA-B15 is rarely found. The aim of this study was to test the hypothesis that gallstone susceptibility genes are more prevalent in Mexicans with recent Amerindian ancestry. METHODS: We carried out a prospective case-controlled study. Subjects were divided into those who had stones visible on gallbladder ultrasound (cases), and those whose ultrasounds were negative for gallstones (controls). Body mass index (BMI) was calculated, and serum lipids and lipoprotein, and glucose levels were measured. Class I HLA (HLA-B) typing was performed by PCR amplification of genomic DNA. RESULTS: Of the 1,101 subjects, 146 were classified as subjects with GD (cases) and 955 as subjects without GD (controls). Mean age of the cases was 53.5 +/- 12.5 yr versus 44.78 +/- 12.0 yr for the controls, p= 0.001. A family history of GD was observed in 48% of the cases versus 28.4% of the controls, p= 0.001. HLA-B39 was more frequently increased in GD subjects (0.162), compared with controls (0.063), p= 0.008. The odds ratio of having HLA-B39 was 2.8 and 95% (CI 95%= 1.3-6.3) for GD; HLA-B15 was more frequently increased in controls than in cases. CONCLUSIONS: The most prevalent HLA alleles detected in these GD cases are characteristic of Amerindian populations, supporting the role of genetics in the high prevalence of the development of GD in Mexican mestizos.  相似文献   
74.
BACKGROUND AND AIMS OF THE STUDY: Left ventricular (LV) contraction is slowed in patients with aortic stenosis (AS). Although the possible role of LV systolic function abnormalities in the assessment of AS severity has been evaluated, current echocardiographic techniques cannot offer precise quantification of LV motion velocity. The study aim was to evaluate an automated segmental motion analysis (ASMA) system to assess AS severity. METHODS: Twenty-two patients with AS, sinus rhythm and preserved LV ejection fraction were studied prospectively. Patients underwent both conventional Doppler echocardiography to measure transaortic gradient and aortic valve area by the continuity equation, and ASMA of the interventricular septum. The ASMA line graph mode displays changes in area through the cardiac cycle. The RR interval and time from the R-wave to peak maximum area shortening were measured, and an ASMA index was calculated. RESULTS: A significant and strong inverse correlation was found between aortic valve area and ASMA index (r = -0.78; 95% CI -0.90 to -0.55; p <0.001). The area under the ROC curve in the diagnosis of severe AS (aortic valve area < or =0.8 cm2) was 0.97 (95% CI 0.90-1.0). Sensitivity, specificity, positive and negative predictive values and overall accuracy for an ASMA index >0.40 were 100, 91.7, 92.3, 100 and 95.8%, respectively. CONCLUSION: The ASMA system may be valuable in evaluating AS, as it offers a strong correlation with aortic valve area calculated by the continuity equation, and very high sensitivity and specificity in the diagnosis of severe AS.  相似文献   
75.
Rouvier J  Scazziota A  Altman R 《Circulation》2002,106(24):e200-1; author reply e200-1
  相似文献   
76.
77.
Dystrophic epidermolysis bullosa is a rare blistering condition caused by mutations in the COL7A1 gene. Different clinical variants have been described, with dominant and recessive inheritance, but no consistent findings have been elucidated to establish a genotype–phenotype correlation. We present three unrelated patients with two identical pathogenic compound heterozygous mutations in the COL7A1 gene that developed different clinical forms of dystrophic epidermolysis bullosa—epidermolysis bullosa pruriginosa and mild recessive non‐Hallopeau–Siemens—raising the possibility of other genetic or environmental modifying factors responsible for the phenotype of the disease.  相似文献   
78.
79.
Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by the selective loss of dopaminergic neurons in the nigrostriatal pathway. The lipophile 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) can cross the blood–brain barrier and is subsequently metabolized into toxic1‐methyl‐4‐phenylpyridine (MPP+), which causes mitochondrial dysfunction and the selective cell death of dopaminergic neurons. The present article reports the neuroprotective effects of silibinin in a murine MPTP model of PD. The flavonoid silibinin is the major active constituent of silymarin, an extract of milk thistle seeds, and is known to have hepatoprotective, anticancer, antioxidative, and neuroprotective effects. In the present study, silibinin effectively attenuated motor deficit and dopaminergic neuronal loss caused by MPTP. Furthermore, in vitro study confirmed that silibinin protects primary cultured neurons against MPP+‐induced cell death and mitochondrial membrane disruption. The findings of the present study indicate that silibinin has neuroprotective effects in MPTP‐induced models of PD rather than antioxidative or anti‐inflammatory effects and that the neuroprotection afforded might be mediated by the stabilization of mitochondrial membrane potential. Furthermore, these findings suggest that silibinin protects mitochondria in MPTP‐induced PD models and that it offers a starting point for the development of treatments that ameliorate the symptoms of PD. © 2015 Wiley Periodicals, Inc.  相似文献   
80.
Data on saccadic latency in patients with Spinocerebellar Ataxia 2 (SCA2) are sparse and contradictory. In order to determine whether saccadic latency is definitely prolonged, identify its possible determinants and evaluate it as disease biomarker we assessed the saccadic latency by electronystagmography in 110 SCA2 patients and their paired controls. Mean saccadic latencies were significantly longer in patients when compared to controls for all tested target displacements. Forty-six percent of SCA2 patients had saccadic latencies above the normal range. Reciprobit plots of saccadic latency demonstrated a skewed distribution in the direction of longer latencies for the patients compared to controls. As saccadic latency increased, the velocity and amplitude of saccades significantly decreased in SCA2 subjects but not in controls. Saccadic latency was not influenced by any demographical, clinical or molecular SCA2 variables, but it showed a significant correlation with the performance of the Stroop test, the verbal fluency test and the Wisconsin Card Sorting Test in SCA2 patients. This paper demonstrated that saccadic latency is prolonged in SCA2 patients and it significantly correlates with the performance of frontal-executive functions, thus this parameter could be a useful biomarker to evaluate the efficiency of future therapeutical options on these dysfunctions.  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