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   5875篇
  免费   422篇
  国内免费   48篇
耳鼻咽喉   77篇
儿科学   188篇
妇产科学   136篇
基础医学   816篇
口腔科学   93篇
临床医学   564篇
内科学   1299篇
皮肤病学   139篇
神经病学   362篇
特种医学   147篇
外科学   829篇
综合类   158篇
预防医学   592篇
眼科学   123篇
药学   453篇
中国医学   25篇
肿瘤学   344篇
  2023年   43篇
  2022年   56篇
  2021年   140篇
  2020年   85篇
  2019年   134篇
  2018年   126篇
  2017年   127篇
  2016年   120篇
  2015年   173篇
  2014年   206篇
  2013年   239篇
  2012年   385篇
  2011年   400篇
  2010年   210篇
  2009年   216篇
  2008年   402篇
  2007年   429篇
  2006年   372篇
  2005年   326篇
  2004年   350篇
  2003年   306篇
  2002年   269篇
  2001年   132篇
  2000年   154篇
  1999年   128篇
  1998年   50篇
  1997年   29篇
  1996年   28篇
  1995年   17篇
  1994年   27篇
  1993年   22篇
  1992年   64篇
  1991年   51篇
  1990年   63篇
  1989年   52篇
  1988年   40篇
  1987年   49篇
  1986年   48篇
  1985年   33篇
  1984年   19篇
  1983年   15篇
  1982年   19篇
  1981年   16篇
  1979年   27篇
  1978年   18篇
  1976年   13篇
  1975年   13篇
  1974年   13篇
  1973年   17篇
  1972年   12篇
排序方式: 共有6345条查询结果,搜索用时 15 毫秒
61.
Twelve laryngeal squamous cell carcinoma cases (7 laryngeal and 5 hypopharyngeal cancer; 15 samples) were analysed by immunohistochemistry for the expression of invasion markers CD44v6/v3, NM23 and matrix metalloproteinase, MMP2. The laryngeal epithelium showed CD44v6+v3+NM23- /MMP2- phenotype. When tumors were grouped into TNM categories the phenotype of the T2 and T3 tumors was similar, characterised by decreased CD44v3+ and lack of MMP2 expressions. Meanwhile the NM23 expression was more frequent in T3 tumors. In T4 stage the frequency of NM23 and MMP2 positive cases increased (5/6 and 4/6, respectively) but there was no correlation with the appearence of lymph node metastasis. Comparison of the phenotype of laryngeal and hypopharyngeal tumors, irrespective of the TNM stages, revealed characteristic differences: T2 stage laryngeal tumors showed decreased CD44v3 and occasional NM23 and MMP2 positivity, while in T3 stage these tumors were characterised by increased frequency of NM23 positivity. The phenotype of the hypopharyngeal tumors was significantly different with a high frequency of MMP2 positive cases (5/6) and NM23+1ow CD44v3+ phenotype. The sharp differences in the phenotypes of laryngeal and hypopharyngeal carcinomas were connected to the differences in their invasive capacity unlike to the size of the tumors, since the T4 stage hypopharyngeal tumors had a significantly smaller size than laryngeal ones, even at lower stages. This work was supported by the Hungarian Ministry of Welfare: ETT No: T-11-100/93  相似文献   
62.
Serving personnel of Armed Forces admitted with tuberculosis between Apr 1996–1999 were evaluated for co-infection of tuberculosis and HIV. Sixty (1.06%) of tuberculosis patients were found to be HIV positive. Initial test was done by spot kits and subsequently confirmed by ELISA on two different samples. Majority of the cases were in sexually active age group 48 (80%). Alcohol and smoking was associated in 80% cases. Thirty six (60%) were sputum smear positive for AFB. Twenty eight (46.7%) gave history of exposure to sex workers. Family members were not available for study. Sero prevalence of HIV in association with tuberculosis is less in Armed Forces compared to civil population.KEY WORDS: HIV, Seroprevalence, Tuberculosis  相似文献   
63.
OBJECTIVE: The objective of this study was to evaluate the use of three-dimensional CT and virtual bronchoscopy in the treatment of neonates, infants, and children with esophageal atresia and tracheal stenosis. CONCLUSION: Long-gap (n = 1) and short-gap (n = 5) esophageal atresia, long-segment stenosis (n = 2), patent poststenting trachea (n = 1), normal trachea without fistula (n = 1), and tracheal bronchus (n = 1) were studied. Fistulas between the lower esophagus and carina were noted in all six cases of esophageal atresia. All CT findings correlated with operative or bronchoscopy findings. Sensitivity and specificity were 100%. Three-dimensional CT and virtual bronchoscopy are accurate and useful techniques in the preoperative assessment of esophageal atresia and tracheal stenosis in neonates, infants, and children.  相似文献   
64.
65.
OBJECTIVE: Recurrent aortic narrowing after repair of aortic coarctation or interrupted aortic arch, as well as diffuse, long-segment aortic hypoplasia, can be difficult to manage. Extra-anatomic ascending aorta-descending aorta bypass grafting through a sternotomy is an alternative approach for this problem. METHODS: Since 1985, 19 patients aged 2 months to 18 years (mean 10.7 years) underwent extra-anatomic bypass with 10- to 30-mm Dacron grafts. The initial diagnosis was coarctation with hypoplastic arch in 15, interrupted aortic arch in 3, and diffuse long-segment aortic hypoplasia in 1. Seventeen of the children had a total of 22 previous operations: transthoracic interposition or bypass graft (n = 7), end-to-end anastomosis (n = 7), subclavian arterioplasty (n = 6), and synthetic patch (n = 2). The mean time from initial repair was 8.0 years (range 0.6-18 years). Three children had previous sternotomies. Cardiopulmonary bypass was avoided in all but 6 patients (5 with simultaneous intracardiac repairs). RESULTS: No hospital or late deaths occurred. On follow-up from 4 months to 14.7 years (mean 7.9 years), no reoperations for recurrent stenosis were performed. Two patients have arm-to-leg pressure gradients: 20 mm Hg at rest in 1 patient and a 60-mm Hg systolic exercise gradient with no resting gradient in the other. One patient required exclusion of an aortic aneurysm at the old coarctation repair site 13 years after extra-anatomic bypass. Three children had subsequent successful cardiac operations. CONCLUSIONS: Extra-anatomic bypass is an effective and relatively easy approach for selected cases of complex or reoperative aortic arch obstruction. It should be considered as an alternative operative technique for complex aortic arch reconstruction.  相似文献   
66.
Since pregnancy-induced hypertension is associated with impaired uteroplacental blood flow, we studied fetoplacental and maternal renin production in controls and subjects with pregnancy-induced hypertension. We measured total, active, and inactive (pro-) renin in maternal serum, fetal arterial and venous blood, and chorion homogenate in eight normotensive term patients and 18 patients with pregnancy-induced hypertension. No differences in active or prorenin were found in maternal blood from normal women or patients with pregnancy-induced hypertension. In contrast, fetal artery and vein, as well as chorionic tissue, contained significantly higher active renin in pregnancy-induced hypertension compared with normal subjects. No difference in fetal or chorionic prorenin was seen in the two groups. Thus active to total renin ratio was higher in the fetus and chorion of subjects with pregnancy-induced hypertension, which suggests enhanced active renin production. These results suggest that pregnancy-induced hypertension is associated with increased activity of the renin-angiotensin system in the fetoplacental unit, which is not reflected in the maternal circulation. This may be an attempt by the fetus and chorionic membranes to maintain vascular homeostasis in the face of altered uteroplacental blood flow.  相似文献   
67.
The plasticity of macrophages with selective functional phenotypes partially arises in respective to their microenvironment. Tumor‐associated macrophages (TAMs) may promote disease progression with tumor specific manner. Here we report that in pediatric malignant soft‐tissue tumors, the presence of TAMs and expression of adiponectin (APN) are heterogeneous. Both APN and TAMs had high expression in rhabdomyosarcoma, especially in the malignant subtype, alveolar rhabdomyosarcoma. To investigate the mode of action of APN on TAM activation, a murine MN/MCA1 sarcoma model was used. The Results revealed that exogenous APN had no effect on MN/MCA1 proliferation but tumor size was markedly reduced in apn?/? mice versus WT controls. The accumulation of TAMs in apn?/? mice was also reduced which correlated to downregulated serum levels of MCP‐1. Likewise, TAMs in apn?/? mice exhibited a M1‐like phenotype, characterized by increase in MHC IIhigh population and M1 phenotypic markers, such as iNOS gene and serum TNF‐α accompanied by a decrease in M2 markers, namely YM1 gene and serum IL‐10. In addition, APN deficiency increased the number of CD4+ T cells, CD8+ T cells and NK cells in tumors and reduced tumor metastasis. The altered phenotype of TAMs in apn?/? mice was associated with a marked decrease in phospho‐p38 and treatment with a p38 MAPK inhibitor significantly reduced tumor size and increased MHC II expression on TAMs in WT mice, implying p38 MAPK signaling pathway may contribute to APN‐mediated TAM polarization. Collectively, our findings suggest that APN may have a potential role in regulating soft tissue sarcoma growth.  相似文献   
68.
PURPOSE: To evaluate the feasibility of concurrent weekly Cis-platinum chemoradiation (CRT) in the curative treatment of primary vaginal cancer. METHODS: A retrospective review was performed of all primary vaginal cancer patients treated with curative intent at the Ottawa Hospital Regional Cancer Centre between 1999 and 2004 using concurrent Cis-platinum CRT. RESULTS: Twelve patients were treated with concurrent weekly CRT. The median age at diagnosis was 56 years (range, 34-69 years), and the median follow-up was 50 months (range, 11-75 months). Ten patients (83%) were diagnosed with squamous cell carcinoma and 2 patients (17%) with adenocarcinoma. The distribution according to stage was as follows: 6 (50%) Stage II, 4 (33%) Stage III, and 2 (17%) Stage IVA. All patients received pelvic external beam radiotherapy (EBRT) concurrently with weekly intravenous Cis-platinum chemotherapy (40 mg/m(2)) followed by brachytherapy (BT). The median dose of EBRT was 4500 cGy given in 25 fractions over 5 weeks. Ten patients received interstitial BT, and 2 patients received intracavitary BT, with the median dose being 3000 cGy. The 5-year overall survival, progression-free survival, and locoregional progression-free survival rates were 66%, 75%, and 92%, respectively. Late toxicity requiring surgery occurred in 2 patients (17%). CONCLUSIONS: For the treatment of primary vaginal cancer, it is feasible to deliver concurrent weekly Cis-platinum chemotherapy with high-dose radiation, leading to excellent local control and an acceptable toxicity profile.  相似文献   
69.

Aim of study

In this study, we have investigated the analgesic and anti-arthritic effects of a traditional Chinese medicine (TCM) combination of Lingzhi and San Miao San (SMS) in a rat model of arthritis induced by Freund's complete adjuvant (FCA).

Materials and methods

Sprague–Dawley rats were induced with monoarthritis by single unilateral injection of FCA into the knee joint. The TCM combination was administered to the rats daily by intraperitoneal injection (50 mg/(kg day)) or via oral administration (500 mg/(kg day)) for 7 days before induction of arthritis and 7 days after. Extension angle that provoked struggling behavior, and size and blood flow of the rat knees were measured to give indexes of allodynia, edema, and hyperemia, respectively. The extent of cell infiltration, tissue proliferation, and erosions of joint cartilage provided additional indexes of the arthritis condition.

Results

FCA injection produced significant allodynia, edema, hyperemia, immune cell infiltration, synovial tissue proliferation, and erosions of joint cartilage in the ipsilateral knees compared with the contralateral saline-injected knees. Intraperitoneal injection of the TCM combination (50 mg/(kg day)) suppressed allodynia, edema, and hyperemia in the inflamed knees, and oral administration (500 mg/(kg day)) suppressed edema and hyperemia. Histological examination showed that the TCM administered by either route reduced immune cell infiltration and erosion of joint cartilage.

Conclusions

These findings suggest the Lingzhi and SMS formulation has analgesic and anti-inflammatory effects in arthritic rat knees, and concur to previous clinical studies that showed the TCM combination reduced pain in rheumatoid arthritis patients, and extends its possible benefit to suppression of inflammatory symptoms in these patients.  相似文献   
70.
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