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   6515篇
  免费   452篇
  国内免费   77篇
耳鼻咽喉   110篇
儿科学   190篇
妇产科学   91篇
基础医学   855篇
口腔科学   279篇
临床医学   519篇
内科学   1467篇
皮肤病学   216篇
神经病学   351篇
特种医学   417篇
外科学   936篇
综合类   39篇
预防医学   362篇
眼科学   161篇
药学   415篇
中国医学   64篇
肿瘤学   572篇
  2024年   8篇
  2023年   64篇
  2022年   136篇
  2021年   270篇
  2020年   158篇
  2019年   194篇
  2018年   235篇
  2017年   201篇
  2016年   280篇
  2015年   324篇
  2014年   350篇
  2013年   381篇
  2012年   574篇
  2011年   516篇
  2010年   331篇
  2009年   214篇
  2008年   373篇
  2007年   350篇
  2006年   320篇
  2005年   315篇
  2004年   276篇
  2003年   222篇
  2002年   188篇
  2001年   115篇
  2000年   110篇
  1999年   96篇
  1998年   38篇
  1997年   31篇
  1996年   29篇
  1995年   17篇
  1994年   24篇
  1993年   20篇
  1992年   26篇
  1991年   42篇
  1990年   20篇
  1989年   31篇
  1988年   23篇
  1987年   18篇
  1986年   14篇
  1985年   12篇
  1984年   5篇
  1983年   6篇
  1982年   7篇
  1981年   7篇
  1980年   10篇
  1979年   15篇
  1974年   5篇
  1973年   5篇
  1970年   4篇
  1966年   7篇
排序方式: 共有7044条查询结果,搜索用时 15 毫秒
141.
142.
Arteriovenous malformations (AVMs) are direct communications between primitive reticular networks of dysplastic vessels that have failed to mature into capillary vessels. Based on angiographic findings, peripheral AVMs can be classified into six types: type I, type IIa, type IIb, type IIc, type IIIa, and type IIIb. Treatment strategies vary with the types. Type I is treated by embolizing the fistula between the artery and the vein with coils. Type II (IIa, IIb, and IIc) AVM is treated as follows: first, reduce the blood flow velocity in the venous segment of the AVM with coils; second, perform ethanol embolotherapy of the residual shunts. Type IIIa is treated by transarterial catheterization of the feeding arteries and injection of diluted ethanol. Type IIIb is treated by transarterial or direct puncture approaches. A high concentration of ethanol is injected through the transarterial catheter or direct puncture needle. When the fistula is large, coil insertion is required to reduce the amount of ethanol. Type I and type II AVMs showed the best clinical results; type IIIb showed a satisfactory response rate. However, type IIIa showed the poorest response rate, either alone or in combination with other types. Clinical success can be achieved by using different treatment strategies for different angiographic AVM types.  相似文献   
143.
144.

Purpose

Endobronchial metastasis is defined as documented extrathoracic malignancies metastatic to the endobronchus within a bronchoscopically visible range. Although the clinical and radiologic findings of endobronchial metastasis are similar to primary lung cancer, treatment and prognosis may be different. We hereby investigated the clinical, radiologic and bronchoscopic aspects of endobronchial metastases (EBM) in Korean patients.

Materials and Methods

A total of 43 patients with EBM who underwent bronchoscopic biopsies from June 1991 to December 2009 at Severance Hospital, Yonsei University College of Medicine in Seoul, Korea, were analyzed retrospectively. We evaluated clinical, radiologic and bronchoscopic characteristics of EBM.

Results

The patients consisted of 27 males and 16 females and their ages ranged from 18 to 77 years. The common primary cancers related to EBM were rectal (16.3%), colon (11.6%), breast (9.3%) and uterine (9.3%) cancers. The mean interval from diagnosis of primary cancer to EBM was 36 months, and the mean survival duration from diagnosis of EBM was 16.1 months in 33 deceased patients.

Conclusion

EBM develop in various types of malignancies at various times with unremarkable manifestations. Therefore, physicians should consider the possibility of EBM, especially if a patient has a history of any malignancy, regardless of respiratory symptoms. Respiratory symptoms related with EBM can be treated by various safe procedures.  相似文献   
145.
The antigenicity of the influenza A virus hemagglutinin is responsible for vaccine efficacy in protecting pigs against swine influenza virus (SIV) infection. However, the antigenicity of SIV strains currently circulating in Japan and Vietnam has not been well characterized. We examined the antigenicity of classical H1 SIVs, pandemic A(H1N1)2009 (A(H1N1)pdm09) viruses, and seasonal human-lineage SIVs isolated in Japan and Vietnam. A hemagglutination inhibition (HI) assay was used to determine antigenic differences that differentiate the recent Japanese H1N2 and H3N2 SIVs from the H1N1 and H3N2 domestic vaccine strains. Minor antigenic variation between pig A(H1N1)pdm09 viruses was evident by HI assay using 13 mAbs raised against homologous virus. A Vietnamese H1N2 SIV, whose H1 gene originated from a human strain in the mid-2000s, reacted poorly with post-infection ferret serum against human vaccine strains from 2000-2010. These results provide useful information for selection of optimal strains for SIV vaccine production.  相似文献   
146.
Cardiopulmonary bypass (CPB) contributes to the secretion of anti-inflammatory cytokines that mediate the inflammatory response observed during open heart surgery. In addition to many factors, type of anesthesia management affects immune response and central nervous system in cardiac surgery. The aim of this study was to assess the effect of propofol versus desflurane anesthesia on systemic immune modulation and central nervous system on patients undergoing coronary artery bypass grafting. Forty patients undergoing elective coronary artery bypass graft surgery with CPB were included in this prospective randomized study. Patients were allocated to receive propofol (n?=?20) or desflurane (n?=?20) for maintenance of anesthesia. The blood samples for IL-6, IL-8, TNF-α, and S100β were drawn just prior to the operation before the induction of anesthesia, second before cardiopulmonary bypass, third after CPB, fourth 4 h postoperatively at the ICU. Major finding in our study is that S100β levels were lower in propofol group when compared to desflurane anesthesia. And also immune reaction was less in patients exposed to desflurane anesthesia when compared to propofol anesthesia as indicated by lower plasma concentrations of IL-8 and IL-6. Propofol is more preferable in terms of S100β for anesthetic management for CABG.  相似文献   
147.

Rationale:

Carbon monoxide (CO) poisoning is associated with direct cardiovascular toxicity. In mild CO poisoning in which cardiovascular life support is not required, the effects of CO on left and right ventricular functions are unknown in patients without cardiac failure.

Objectives:

Echocardiography was used to determine whether or not mild CO poisoning impairs ventricular function. Twenty otherwise healthy patients with CO poisoning and 20 age- and gender-matched controls were studied. Echocardiographic examinations were performed at the time of admission and 1 week after poisoning.

Results:

The impairment observed in the left and right ventricular diastolic function at the time of admission was greater than the impairment 1 week after poisoning. Mild CO poisoning did not have a significant effect on systolic function. Carboxyhemoglobin levels were positively correlated with left ventricular diastolic dysfunction, whereas the levels were not correlated with right ventricular diastolic function.

Conclusions:

In CO intoxication, the development of left and right ventricular diastolic dysfunction precedes systolic abnormality. Patients with mild CO poisoning do not manifest cardiovascular symptoms; however, it should be borne in mind that most of these patients have myocardial involvement.  相似文献   
148.
To determine the fascial configuration between the superior mesenteric artery and vein and the posterior aspect of the pancreas, we examined histological sections of 10 elderly donated cadavers without pathology in the abdomen. The retropancreatic fascia was absent along the pancreatic parenchyma facing the artery and vein. Abundant nerves along the artery were separated from the pancreas by loose tissue almost 10 mm in thickness. In addition, anterior renal fasciae facing the pancreatic body were not evident in these specimens, possibly due to the degeneration of the left adrenal gland with age. Thus, a definite renal fascia was restricted on the lateral and posterior sides of the left kidney. These findings suggest that interactions between a pancreatic tumor and nerves would require migration of cancer cells over a long distance. Conversely, attachment of the enlarged tumor mass to the nerves may be necessary for the invasion. The anterior renal fascia may fuse with the retropancreatic fascia.  相似文献   
149.

Purpose

The palatal mucosa is a major donor site for connective tissue in the field of periodontal plastic surgery, since it satisfies both the esthetic and functional demands of patients. The purpose of this study was to use histomorphometric analysis to measure the thicknesses of the palatal mucosa and the lamina propria including the epithelium on cadavers.

Methods

Thirty-four hemimaxillae of cadavers were examined (13 male and 4 female, mean age 57.2 years). Each maxilla was processed for histological sectioning and subsequently for histomorphometric analysis. The thicknesses of the palatal mucosa and the lamina propria including the epithelium were measured at three points starting from the alveolar crest, at intervals of 4 mm, with the aid of Adobe Photoshop.

Results

The thickness of the palatal mucosa at the alveolar crest and at 4 and 8 mm below the alveolar crest were 2.51 ± 0.83 (mean ± SD), 2.92 ± 0.80, and 3.62 ± 0.99 mm, respectively, and thus increasing from the alveolar crest toward the midpalatal suture. Conversely, the thicknesses of the lamina propria including the epithelium at these same positions were 2.06 ± 0.70, 1.54 ± 0.48, and 1.28 ± 0.46 mm, respectively, thus decreasing toward the midpalatal suture.

Conclusions

The present results indicate that clinicians need to be particularly careful when harvesting palatal mucosa that is destined to be used as autogenous donor material for connective tissue in periodontal plastic surgery.  相似文献   
150.
We aimed to determine the pathogenesis of gastric mixed adenoneuroendocrine carcinoma (MANEC) and pure neuroendocrine carcinoma (NEC), which is largely unknown. Targeted DNA sequencing was performed on 34 tumor samples from 21 patients – 13 adenocarcinoma (ADC)/NEC components from MANECs and eight pure NECs – and 21 matched non‐neoplastic gastric tissues. Mutational profiles of MANECs/NECs were compared with those of other tumors using public databases. The majority (64.1%; 59/92) of mutations in MANEC were shared by both ADC and NEC components. TP53 was the most commonly mutated gene in MANEC (69.2%, 9/13) and pure NEC (87.5%, 8/9). All TP53 mutations in MANEC were pathogenic mutations and were shared by both ADC and NEC components. A subset of TP53WT MANECs had a microsatellite‐unstable phenotype or amplifications in various oncogenes including ERBB2 and NMYC, and the only TP53WT pure NEC harbored MYC amplification. Compared to NEC in other organs, NECs arising from the stomach had unique features including less frequent RB1 mutations. Differentially altered genes of MANEC ADC components were significantly associated with receptor tyrosine kinase signaling pathways, while differentially altered genes of MANEC NEC components were significantly associated with the NOTCH signaling pathway. Our data provide evidence suggesting a possible clonal origin of ADC and NEC components of MANEC, and we found that gastric MANECs and pure NECs are distinct entities with unique mutational profiles and underlying protein networks. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  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