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   22867篇
  免费   1415篇
  国内免费   218篇
耳鼻咽喉   381篇
儿科学   327篇
妇产科学   298篇
基础医学   3905篇
口腔科学   395篇
临床医学   1879篇
内科学   4504篇
皮肤病学   752篇
神经病学   1951篇
特种医学   1233篇
外科学   3069篇
综合类   88篇
一般理论   4篇
预防医学   859篇
眼科学   493篇
药学   2124篇
中国医学   296篇
肿瘤学   1942篇
  2024年   16篇
  2023年   200篇
  2022年   507篇
  2021年   830篇
  2020年   425篇
  2019年   594篇
  2018年   690篇
  2017年   523篇
  2016年   790篇
  2015年   1012篇
  2014年   1156篇
  2013年   1372篇
  2012年   2028篇
  2011年   1946篇
  2010年   1127篇
  2009年   910篇
  2008年   1409篇
  2007年   1300篇
  2006年   1217篇
  2005年   1098篇
  2004年   952篇
  2003年   825篇
  2002年   723篇
  2001年   428篇
  2000年   401篇
  1999年   340篇
  1998年   169篇
  1997年   128篇
  1996年   124篇
  1995年   103篇
  1994年   84篇
  1993年   72篇
  1992年   104篇
  1991年   99篇
  1990年   80篇
  1989年   75篇
  1988年   76篇
  1987年   68篇
  1986年   55篇
  1985年   53篇
  1984年   37篇
  1983年   43篇
  1982年   30篇
  1981年   22篇
  1980年   28篇
  1979年   40篇
  1978年   23篇
  1977年   24篇
  1976年   18篇
  1975年   16篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
142.
OBJECTIVE: Otitis media with effusion is one of the most common and intractable ear diseases. However, the role of Th1, Th2, and immunoregulatory cytokines on the pathogenesis of the disease in adult patients remains to be determined. The aim of this study is to disclose the cytokine expression in middle ear effusions (MEEs) in adults and to compare the profile on the basis of the presence of allergic rhinitis and the type of effusions. STUDY DESIGN: A prospective controlled clinical study. PATIENTS: MEEs were collected from 80 adult subjects. The concentration of interleukin (IL)-2, IL-4, IL-5, IL-10, IL-12, and interferon (IFN)-gamma in MEEs were determined by using enzyme-linked immunosorbent assay. RESULTS: IL-2, IL-4, IL-5, IL-10, IL-12, and IFN-gamma in MEEs were detected in 60 (75.0%), 33 (41.3%), 42 (52.5%), 14 (17.5%), 80 (100%), and 66 (82.5%) samples, respectively. Among these cytokines, only the concentration of IL-4 in the allergic rhinitis-positive group was significantly higher than that in the allergic rhinitis-negative group. On the other hand, IL-2, IL-12, and IFN-gamma were detected, regardless of the presence of allergic rhinitis, and the concentration of these cytokines correlated with each other. The correlation between the concentration of IL-4 and IL-5 was also detected. In addition, both the incidence rate and the concentration of IL-10 in MEEs were significantly higher in the mucoid type compared with those in the serous type effusions. CONCLUSION: Regardless of allergic status, IL-12 may play a critical role in the pathogenesis of otitis media with effusion by affecting the production of IL-2 and IFN-gamma. In addition, IL-4 may have some impact on the immunologic condition in adults with allergic rhinitis. IL-10 potentially affects the viscosity of MEEs.  相似文献   
143.
144.
To develop the new gel formulations that show sustained release for a period of time, the bioadhesive carbopol gels containing tretinoin were prepared. The release characteristics of drug from the carbopol gel were studied according to temperature, receptor medium and drug concentration. For the enhancement of its percutaneous absorption, some kinds of penetration enhancer were used. As the concentration of drug increased, the release of drug from the gel increased, showing concentration dependency. The increase of temperature showed the increased drug release, depending on the activation energy of permeation. Among the enhancers used such as the glycols and the non-ionic surfactants, polyoxyethylene 2-oleyl ether showed the best enhancing effect. The carbopol gels of tretinoin containing an enhancer could be developed for the enhanced transdermal delivery of drug.  相似文献   
145.
It has been suggested that expression of anti-apoptotic proteins such as Bcl-2 or BAG-1 may confer cellular resistance to chemotherapy. A corollary of this hypothesis is that expression of these proteins may predict clinical response to treatment and that Bcl-2- or BAG-1-positive cells may selectively be enriched in postchemotherapy tissue specimens. The goal of this exploratory pilot study was to assess these two predictions by using immunohistochemistry in 29 paired pre- and postchemotherapy breast tissue specimens obtained from patients who underwent preoperative doxorubicin-based chemotherapy. All breast cancers expressed BAG-1 protein, and, in individual tumors, 40-100% of neoplastic cells stained positive for this protein. Homogenous cytoplasmic staining was typically observed, though neoplastic cells also showed nuclear staining in many specimens. We found no correlation between prechemotherapy expression of BAG-1 and subsequent pathological response to cytotoxic therapy. Paired pre- and posttreatment specimens showed similar levels of BAG-1 expression when residual tumor could be assessed. Bcl-2 was expressed in 55% of cancers and was localized to the cytoplasm. Absence of Bcl-2 expression in prechemotherapy specimens was associated with more frequent complete pathological response (58% vs. 20%; p = 0.04). However, similar to BAG-1, no difference between pre- and posttherapy expression of Bcl-2 was observed in neoplastic cells in paired tissue specimens. These observations suggest that BAG-1 contributes an important cellular function to breast epithelial cells, which is reflected by its ubiquitous expression in these tissues. However, it does not appear to determine response to doxorubicin-based chemotherapy. In contrast, lack of Bcl-2 expression was associated with a higher probability of complete pathological response to doxorubicin-based chemotherapy.  相似文献   
146.
Yang DM  Yoon MH  Kim HS  Kim HS  Shin DB 《Clinical imaging》2000,24(4):217-220
Most intrarenal pseudoaneurysms result from a laceration of the renal artery or its branches. However, tumor-induced renal pseudoaneurysm is very rare. We report a case in which embolization of an intrarenal pseudoaneurysm complicating renal metastases resulting from a choriocarcinoma was successful.  相似文献   
147.
Alveolar soft part sarcoma: MR and angiographic findings   总被引:5,自引:5,他引:0  
Suh JS  Cho J  Lee SH  Shin KH  Yang WI  Lee JH  Cho JH  Suh KJ  Lee YJ  Ryu KN 《Skeletal radiology》2000,29(12):680-689
Objective. To present the MR and angiographic findings of alveolar soft part sarcoma (ASPS). Design and patients. MR examinations (12 tumors of 10 patients) of ASPS performed at multiple hospitals were retrospectively reviewed. The tumors were found in the thigh (n=4), lower leg (n=4), femur (n=2, local metastasis), scalp (n=1) and arm (n=1). The MR signal characteristics including signal intensity, homogeneity and signal void of lesions and bony invasion including direct invasion or local metastasis were evaluated. Angiographic findings (n=4) and post-embolotherapy follow-up MR imaging (n=2) findings were also assessed. Results. Local bony metastasis was found in two cases. Seven tumors showed heterogeneous high signal intensity on T1- and T2-weighted images with good enhancement. One tumor had a very high signal on T1-weighted images. Eight tumors (67%) showed numerous signal voids in or near the tumors. All four angiographic studies showed numerous enlarged vessels, arteriovenous shunts and delayed washout. Two cases mimicked arteriovenous malformations on angiographic studies but MR images demonstrated solid soft tissue components as well as tortuous vessels. Conclusions. High signal on T1-weighted image and numerous signal voids are highly suggestive of ASPS, although they are not universal as has been suggested and arteriovenous malformation should be included in the differential diagnosis. Local bony metastases in ASPS were seen in two cases and should be carefully investigated. Received: 12 April 2000 Revision requested: 27 June 2000, 8 August 2000 Revision received: 2 August 2000, 21 August 2000 Accepted: 22 August 2000  相似文献   
148.
Selective serotonin reuptake inhibitors (SSRIs) have wide indications for the treatment of anxiety disorders, including panic disorder, generalized anxiety disorder, posttraumatic stress disorder, obsessive-compulsive disorder and social anxiety disorder in addition to depression. Until recently, no animal model has been available for screening the anxiolytic effect of SSRIs and studying its mechanism of action. We have investigated the relationship between serotonin neurotransmission and anxiety using conditioned fear stress (CFS), an animal model of anxiety. CFS increased serotonin neurotransmission in the medial prefrontal cortex and amygdala. In behavioral pharmacological studies, SSRIs, serotonin1A agonists and monoamine oxidase inhibitors, which are assumed to facilitate serotonin neurotransmission, decreased conditioned freezing, an index of anxiety or fear, in CFS. In vivo microdialysis studies showed that serotonin neurotransmission in the medial prefrontal cortex increased after recovery from the freezing behavior. Microinjection of SSRI to the basolateral nucleus of the amygdala reduced conditioned freezing, indicating that the amygdala is one of target brain sites of anxiolytic action of SSRIs. Furthermore, CFS-induced c-Fos expression in the basolateral nucleus of the amygdala was reduced by SSRI pretreatment. Taken together, recent studies indicate that facilitation of brain serotonin neurotransmission decreases anxiety in agreement with the clinical evidence.  相似文献   
149.
Surgical treatment of intractable epilepsy accompanying cortical dysplasia   总被引:3,自引:0,他引:3  
OBJECT: Surgical treatment of cortical dysplasia (CD) together with intractable seizures is challenging because both visualization and localization of the lesion are difficult, correlation with seizure foci requires comprehensive study, and the surgical outcomes reported thus far are unsatisfactory. The authors report their experience in the surgical treatment of CD classified according to a surgical point of view. METHODS: The definition of CD used in this study was a dysplastic lesion visible on magnetic resonance (MR) images or a lesion that, although not visible on MR images, was diagnosed as moderate-to-severe dysplasia by using pathological analysis. During the last 4.5 years, the authors treated 36 patients with intractable epilepsy accompanied by CD. They divided the 36 cases of CD into four characteristic groups: Group A, diffuse bilateral hemispheric dysplasia; Group B, diffuse lobar dysplasia; Group C, focal dysplasia; and Group D, a moderate to severe degree of CD with a normal appearance on MR images. All but one patient in Group C were monitored in the epilepsy monitoring unit by using subdural electrodes for seizure localization and functional mapping. The incidence of CD among a cohort of 291 patients who had undergone epilepsy surgery at the authors' center during the study period was 12.4%. The mean age of the 36 patients was 21.3 years and the mean age at seizure onset was 8.5 years. The mean follow-up period was 26 months. Twenty-six patients (72.2%) belonged to Engel Class I or II (20 and six, respectively). There were five cases in Group A, nine in Group B, nine in Group C, and 13 in Group D. Patients in Groups A and B were significantly younger at seizure onset and had significantly poorer surgical outcomes compared with patients in Groups C and D (p < 0.05). If outcome is compared on the basis of the extent of removal of CD, patients in whom CD was completely removed had significantly better outcomes than those in whom CD was only partially removed (p < 0.001). CONCLUSIONS: The authors conclude that intractable epilepsy accompanied by CD can be treated surgically using comprehensive preoperative approaches. Deliberate resective procedures aimed at complete removal of dysplastic tissue ensure excellent seizure control without permanent neurological deficit.  相似文献   
150.
BackgroundThe aim of this study was to evaluate clinical outcomes of sodium tetradecyl sulphate (STS) sclerotherapy for conservative treatment of lateral malleolar bursitis of the ankle.MethodsWe reviewed data from 20 consecutive patients (20 ankles) who underwent STS sclerotherapy between August 2018 and June 2019. After aspiration of fluid from the lateral malleolar bursal sac, 2 mL (20 mg) STS was injected into the sac. Clinical outcomes and side effects and complications were evaluated at 2 weeks, 3 months, 1 year, and 2 years after sclerotherapy. Responses to treatment were assessed according to degree of fluctuation, shrinkage of the bursal sac, and soft-tissue swelling. The 36-item short form survey (SF-36) was completed for each patient before and after therapy.ResultsComplete response was observed in 17 patients (85%), and partial response was observed in 3 patients (15%) after STS sclerotherapy. SF-36 physical component scores improved from 62.2 (interquartile range, 5.2) before therapy to 70.0 (interquartile range, 7.9) at last follow-up (p < 0.05). One patient (5%) experienced transient hyperpigmentation at the injection site. No major complications occurred.ConclusionsSTS sclerotherapy was an effective and safe treatment for patients with lateral malleolar bursitis of the ankle.  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