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   11658篇
  免费   715篇
  国内免费   93篇
耳鼻咽喉   74篇
儿科学   321篇
妇产科学   296篇
基础医学   1637篇
口腔科学   159篇
临床医学   925篇
内科学   3011篇
皮肤病学   164篇
神经病学   1635篇
特种医学   437篇
外科学   1053篇
综合类   31篇
一般理论   5篇
预防医学   583篇
眼科学   165篇
药学   882篇
中国医学   13篇
肿瘤学   1075篇
  2024年   28篇
  2023年   186篇
  2022年   314篇
  2021年   551篇
  2020年   303篇
  2019年   428篇
  2018年   474篇
  2017年   335篇
  2016年   404篇
  2015年   437篇
  2014年   611篇
  2013年   699篇
  2012年   933篇
  2011年   1002篇
  2010年   549篇
  2009年   517篇
  2008年   741篇
  2007年   680篇
  2006年   664篇
  2005年   575篇
  2004年   431篇
  2003年   378篇
  2002年   328篇
  2001年   79篇
  2000年   75篇
  1999年   95篇
  1998年   63篇
  1997年   44篇
  1996年   42篇
  1995年   33篇
  1994年   27篇
  1993年   25篇
  1992年   25篇
  1991年   40篇
  1990年   33篇
  1989年   35篇
  1988年   34篇
  1987年   22篇
  1986年   30篇
  1985年   17篇
  1984年   13篇
  1983年   16篇
  1982年   13篇
  1981年   18篇
  1980年   9篇
  1979年   20篇
  1978年   10篇
  1977年   8篇
  1973年   8篇
  1966年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
We describe two episodes of CMV retinitis in a pediatric patient who underwent a CD34+ selected graft from his haploidentical father. Both recipient and donor were cytomegalovirus (CMV) seropositive. Both episodes occurred late post-grafting during a phase of complete immunological recovery with sufficient numbers of circulating CMV-specific clones. Antiviral treatment with foscarnet and ganciclovir was successful but prolonged treatment was required to prevent relapses. We hypothesize that this complication was more related to an immune reconstitution process than to an immune-deficient state post-grafting. We conclude that CMV retinitis is a late complication of HSCT that can occur despite satisfactory immune reconstitution. Usually, it is responsive to antiviral therapy. Dilated fundoscopic examination is essential both for examining patients with reduced visual acuity and for screening asymptomatic patients.  相似文献   
104.
BACKGROUND: The aim of this study was to assess the extent to which a more widespread use of new effective treatments for heart failure associated with earlier detection of the disease may have contributed to enhancing the prognosis of idiopathic dilated cardiomyopathy (IDC) patients over the past 20 years. METHODS: Heart transplant-free survival curves were analyzed in 343 IDC patients, prospectively enrolled from January 1, 1978 to June 30, 1997 in the Heart Muscle Disease Registry of the Cardiology Department in Trieste (94 enrolled between 1978 and 1987, Group 1; 249 between 1988 and 1997, Group 2). At enrollment, 91 patients had no heart failure symptoms (NoHF), whereas the remaining 252 showed HF of recent (HF < or = 6 months, n = 132) or non-recent (HF > 6 months, n = 120) onset. RESULTS: In comparison to Group 1, Group 2 was treated more frequently with ACE-inhibitors and beta-blockers (p < 0.0001) and showed a better long-term survival (p = 0.0034), resulting from a reduction of death for refractory HF or need for heart transplant (p = 0.011). Conversely, the risk of sudden death did not significantly differ between the two groups. NoHF, HF > 6 months and HF < or = 6 months groups were similarly treated with ACE-inhibitors and beta-blockers. Long-term survival was better in patients without HF than in those with overt HF (p = 0.0015). As compared to Group HF > 6 months, Group HF < or = 6 months had a poorer one-year prognosis (p = 0.045), related to the presence of a subgroup of patients with refractory HF and need for heart transplant, but showed a better survival rate over the following years (p = 0.015). Over the two subsequent decades of enrollment, a significant improvement in patient survival was observed within Groups NoHF (p = 0.03) and HF > 6 months (p = 0.01), but not in Group HF < or = 6 months. CONCLUSIONS: Over the past 20 years, the increasing use of ACE-inhibitors and beta-blockers in IDC was associated with a significant improvement in long-term survival, resulting from a reduction in mortality for refractory heart failure or need for heart transplant. In addition, early diagnosis may have contributed significantly to enhancing the prognosis of IDC, since the benefits of medical therapy were lower in patients identified and treated in advanced stages of the disease. Moreover, early diagnosis was shown to be useful in recognizing patients with recent onset of heart failure who are not responders to aggressive medical treatments and urgently need heart transplant.  相似文献   
105.
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   
106.

Post–mortem computed tomography (PMCT) is a routine tool in many forensic pathology departments as it is fast and non-destructive and allows less gruesome visualization than photographs, and the images are indefinitely storable. Several studies investigated congruence between PMCT and autopsy for skull fracture but registered only the presence or absence of fracture systems. The objective of this study was to determine location-specific sensitivity and specificity of PMCT for individual fracture lines in blunt force head trauma. Accurate 3D models based on PMCT data with all fracture lines visible are important for future studies on fractures, applying finite element analysis (FEA). We retrospectively sampled adult cases from 2013 to 2019 with skull fracture mentioned in the autopsy report. PMCT was on a Siemens 64-slice scanner and autopsy according to international guidelines. The location and direction of all fracture lines at autopsy and at de novo interpretation of scans were registered and compared. Ninety-nine cases with 4809 individual findings were included. Age ranged from 18 to 100 years. The overall sensitivity was 0.58, and specificity was 0.91. For individual locations, sensitivity ranged from 0.24 to 0.85, and specificity ranged from 0.73 to 1.00. Intra-observer agreement was 0.74, and inter-observer agreement ranged from 0.43 to 0.58. In conclusion, PMCT is suited for detection of fracture systems, but not for detection of all individual fracture lines. Our results differed from the existing literature due to the methodological choices of registering individual fracture lines. Future studies utilising FEA must supplement PMCT with autopsy data.

  相似文献   
107.
Corynebacterium species that are normally abundant on the skin and mucous membranes rarely cause infections and are susceptible to most antibiotics. The report in 1976 of four cases of sepsis at the National Institutes of Health caused by a hitherto undescribed Corynebacterium that is highly antibiotic resistant, but uniformly susceptible to vancomycin, alerted the medically oriented scientific community to the emergence of these organisms as a possible new cause of nosocomial infections. Although we have always performed antibiotic susceptibility tests on all microorganisms recovered from normally sterile body fluids, our first recovery of these organisms was in August 1977. Since then we have recovered 52 such strains from 39 patients, most frequently from the rectum, followed by the groin, blood, lesions and urine in order of predominance. Characterization by API 50 L strips revealed that most, but not all strains resemble the JK group of Riley et al. [1]. Cell wall studies and DNA base ratios further confirmed their status as corynebacteria. Hospital acquisition has been proved; cross infection between patients is the most likely mode of spread. Their recognition is necessary for optimal preventive and therapeutic care of patients with compromised host defenses.  相似文献   
108.
In order to assess high-pressure barocepture sensitivity and parasympathetic function in elderly patients with silent myocardial ischemia, we selected 45 inpatients in our geriatric unit for a prospective cohort study of patients with coronary heart disease. All patients were over 65 years of age (37 men and 8 women) and had coronary heart disease, documented by an angiographic study and electrocardiographic evidence of myocardial ischemia during exercise stress testing, performed according to the Bruce protocol. The subjects were divided in three subgroups: group 1 (22 patients) with electrocardiographic and echocardiographic history of myocardial infarction but no angina chest pain during exercise testing; group 2 (13 patients) with no exercise induced chest pain; and group 3 (10 patients) with exercise-induced chest pain. Baroceptor sensitivity was assessed in all subjects, by evaluating heart rate changes expressed in RR interval on the basis of changes in the mean arterial pressure during intravenous infusion of stepwise doses (50-100 and 150 mug) of phenylephrine hydrochloride. Heart rate changes were also evaluated during overshoot of the Valsalva maneuver (Valsalva max.), providing an index of parasympathetic activity. Our results showed that group two patients (only silent ischemia) had significantly (P>0.001) greater baroceptor sensitivity than the other two groups (group 2; 15.2+/-1.9 ms/mmHg; group 1: 10.0+/-1.7 ms/mmHg; and group 3: 9.8+/-1.7 ms/mmHg). Group two also showed a significant positive correlation (r=0.58; P<0.05) between baroceptor sensitivity and end-diastolic pressure and a significant inverse correlation (r=-0.672; P<0.05) between baroceptor sensitivity and the ejection fraction. Group 2 patients had a significantly longer RR interval than group 1 (P<0.05) and group 3 (P<0.05); a significant positive correlation (r=0.620; P<0.05) between Valsalva max. and end-diastolic pressure; and a significant inverse correlation (r=0.694; P<0.05) between Valsalva max. and the ejection fraction. Valsalva max. and baroceptor sensitivity correlated significantly in all three groups (group 1, r=0.707; P<0.001; group 2, r=0.94; P<0.001; and group 3; r=0.833; P<0.05). In conclusion our data suggest that elderly patients with silent ischemia appear to have an increased capacity for evoking parasympathetic reflexes that could inhibit pain perception.  相似文献   
109.
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   
110.
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