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   8773篇
  免费   545篇
  国内免费   57篇
耳鼻咽喉   61篇
儿科学   198篇
妇产科学   122篇
基础医学   823篇
口腔科学   173篇
临床医学   777篇
内科学   2271篇
皮肤病学   81篇
神经病学   1186篇
特种医学   282篇
外科学   1573篇
综合类   21篇
一般理论   1篇
预防医学   363篇
眼科学   208篇
药学   458篇
中国医学   14篇
肿瘤学   763篇
  2024年   9篇
  2023年   124篇
  2022年   207篇
  2021年   391篇
  2020年   230篇
  2019年   301篇
  2018年   308篇
  2017年   236篇
  2016年   272篇
  2015年   285篇
  2014年   412篇
  2013年   494篇
  2012年   761篇
  2011年   709篇
  2010年   363篇
  2009年   365篇
  2008年   543篇
  2007年   528篇
  2006年   545篇
  2005年   450篇
  2004年   407篇
  2003年   358篇
  2002年   309篇
  2001年   67篇
  2000年   54篇
  1999年   66篇
  1998年   41篇
  1997年   39篇
  1996年   47篇
  1995年   28篇
  1994年   34篇
  1993年   28篇
  1992年   39篇
  1991年   38篇
  1990年   21篇
  1989年   34篇
  1988年   19篇
  1987年   15篇
  1986年   20篇
  1985年   18篇
  1984年   28篇
  1983年   17篇
  1982年   14篇
  1981年   17篇
  1980年   8篇
  1979年   13篇
  1977年   6篇
  1976年   6篇
  1975年   10篇
  1974年   10篇
排序方式: 共有9375条查询结果,搜索用时 31 毫秒
91.
92.
Clinical Rheumatology - Kawasaki disease (KD) is the most frequent cause of acquired heart disease in children in high-income countries because of coronary artery involvement. Risk factors for...  相似文献   
93.
94.
The absence or very low levels of plasminogen cause a rare disabling disease called ligneous conjunctivitis, characterized by the growth of fibrin-rich pseudomembranes in the conjunctiva and on other mucosal surfaces. Several mutations have been detected in the plasminogen gene of patients affected with ligneous conjunctivitis. The human plasminogen gene, located on chromosome 6, has a marked homology with the genes belonging to the plasminogen-apo(a) family, and with a number of pseudogenes and plasminogen-like genes located on chromosome 2. This work describes a series of nucleotide variations related to genes other than the plasminogen one, found during the genetic characterization of plasminogen defect in two unrelated patients with ligneous conjunctivitis. The results of automated sequences of each exon and intron-exon boundaries were compared with those of the human plasminogen gene from the NCBI gene bank. In particular, a co-amplified gene on chromosome 2 mimicking a 14 bp deletion in exon 5 of the plasminogen gene was identified by sequencing two different bands obtained from a long run of the PCR exon 5 product in NuSieve agarose gel, and by PstI restriction enzyme analysis of the same amplicons. Moreover, 21 single nucleotide exchanges due to plasminogen-like genes co-amplification were observed, namely one in exon 1, two in exon 4, three in exons 3, 5 and 16, four in exon 13, and five in exon 17. In conclusion, these data confirm the difficulty of plasminogen genetic analysis and may help researchers to better identify the true plasminogen gene mutations causing molecular defects.  相似文献   
95.
Purpose

To evaluate the reproducibility of the 2D shear wave elastography (2D-SWE) method and to identify the prognostic factors of breast lesions.

Methods

In this prospective study, 44 female patients were consecutively included from January 2020 to September 2021. All patients showing visible masses at B-mode ultrasound underwent to clinical evaluation, followed by qualitative and quantitative 2D-SWE by two different operators with over 15-year and 2-year experience, respectively. Subsequently, patients underwent to surgical treatment after core needle biopsy. Reproducibility of qualitative and quantitative 2D-SWE was evaluated by Cohen’s kappa and intraclass correlation coefficient (ICC). Clinical, imaging, and histopathological data and 2D-SWE evaluations were analysed with Spearman's rank correlation test.

Results

The mean age of the patients was 55 years?±?12. The mean histological and ultrasound tumour size of were 23.1 mm?±?13.2 and 17.2 mm?±?10.2, respectively. The interobserver agreement showed a good reproducibility limited to the qualitative evaluation colour maps (Cohen’s kappa?=?0.603) and to the quantitative evaluation E ratio (ICC?=?0.771). Correlation analysis between the ultrasound and 2D-SWE values and the clinical-pathological parameters showed a significant relationship between E ratio and Elston–Ellis grading (P?<?0.030) and between tumour size and Elston–Ellis grading (P?<?0.041).

Conclusion

The 2D-SWE has shown good reproducibility among operators with different experience. It could be a promising tool in the evaluation of some prognostic factors in ultrasound visible breast cancer.

  相似文献   
96.
We have previously shown that the life cycles of several viruses are influenced by host-cell redox states. Reports of the antioxidant activities of the plant polyphenol resveratrol (RV) prompted us to investigate its effects on influenza virus replication in vitro and in vivo. We found that RV strongly inhibited the replication of influenza virus in MDCK cells but that this activity was not directly related to glutathione-mediated antioxidant activity. Rather, it involved the blockade of the nuclear-cytoplasmic translocation of viral ribonucleoproteins and reduced expression of late viral proteins seemingly related to the inhibition of protein kinase C activity and its dependent pathways. RV also significantly improved survival and decreased pulmonary viral titers in influenza virus-infected mice. No toxic effects were observed in vitro or in vivo. That RV acts by inhibiting a cellular, rather than a viral, function suggests that it could be a particularly valuable anti-influenza drug.  相似文献   
97.
Seventeen year old identical twin brothers with no family history of cardiopathy began experiencing palpitations almost simultaneously. In both, examination revealed marked cardiomegaly and hypokinesia of the ventricular walls, and clinical and radiologic signs of progressive cardiac failure developed a few days later. Both boys died suddenly, 49 days and 5 months, respectively, after the initial examination. Electrocardiographic and vectorcardiographic studies revealed a severe intraventricular conduction disturbance that coincided with histologic changes in the myocardial tissue, including profuse interstitial fibrosis, hypertrophy and degeneration of the myocardial fibers, aberrant arrangement of the muscular fibers and considerable alteration of the structure of cardiac tissue. In the absence of hereditary and chromosomal factors, and excluding possible viral intervention during fetal life, it is believed that a teratogenic factor can produce the structural alterations of the tissue and derangement of the fibers observed in these hearts.The irregular contractions of the heart at the level of the net-like meshwork, disarrangement of myocardial fibers, and adaptative mechanisms of the heart inherent in the destruction of the contractile tissue contributed to the functional cardiac disorders that resulted in congestive heart failure and sudden death in these twins.  相似文献   
98.
Summary The aim of the present study was to evaluate possible hemodynamic effects of somatostatin in insulin-dependent diabetic subjects. For this purpose, 7 insulin-requiring juvenile-onset diabetics were submitted to a short-term infusion of cyclic somatostatin (250 μg/h, over 2 h) or saline in randomized order. Somatostatin infusion resulted in a progressive and significant decrease in heart rate, stroke volume, cardiac index and velocity circumferential fiber; on the other hand, left ventricular ejection time was augmented by somatostatin. None of these effects was seen in the saline control study. We conclude that somatostatin exerts a negative inotropic effect in insulin-dependent diabetes.  相似文献   
99.
Two nonsense polymorphisms of Z-dependent protease inhibitor (ZPI; Serpina10) have been identified. To assess the risk of venous thromboembolism (VTE) associated with W303x and R67X Serpina10 mutations, we performed a meta-analysis of studies comparing the prevalence of these two mutations in VTE patients and in controls Odds Ratios (ORs) and 95% confidence intervals (CIs) were calculated for each trial and pooled using a random-effects model. Five studies involving 5000 patients were included. R67X and W303X mutations of Serpina10 were not associated with increased VTE risk (OR 1.63; 95% CI 0.84, 3.16 and OR 1.21; 95% CI 0.29, 4.98 respectively).  相似文献   
100.
BACKGROUND: Controversy prevails regarding the existence of a correlation between the severity of coronary artery disease (CAD) and the extent and distribution of obesity. PURPOSE: To assess the correlation between total fat, truncal fat (TF), and lean mass, obtained with dual-energy X-ray absorptiometry (DEXA) and standard anthropomorphic indices (body mass index, waist circumference, waist-to-hip ratio) and to verify whether DEXA indices can predict the extent and severity of CAD. MATERIALS AND METHODS: Fifty-eight patients (19 females) consecutively referred for coronary angiography underwent physical examination and DEXA assessment of body composition. RESULTS: Of the 58 patients enrolled, 22 were overweight and 13 were obese. Significant CAD was found in 39 (67%) patients. DEXA-derived total mass and fat mass enabled us to distinguish overweight from obese patients (P<0.005), whereas just TF mass correlated with the number of diseased vessels after adjusting for body mass index, sex, age, and smoking habit (odds ratio, 8.68; 95% confidence interval: 1.02-74.10). CONCLUSION: TF determined by DEXA is independently related with CAD extension.  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