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   1418568篇
  免费   108112篇
  国内免费   4516篇
耳鼻咽喉   18020篇
儿科学   45708篇
妇产科学   38384篇
基础医学   208524篇
口腔科学   37860篇
临床医学   137663篇
内科学   276587篇
皮肤病学   27584篇
神经病学   119271篇
特种医学   51233篇
外国民族医学   369篇
外科学   197820篇
综合类   30047篇
现状与发展   2篇
一般理论   532篇
预防医学   121004篇
眼科学   31299篇
药学   104174篇
  6篇
中国医学   3278篇
肿瘤学   81831篇
  2021年   12252篇
  2019年   12936篇
  2018年   17944篇
  2017年   13462篇
  2016年   14552篇
  2015年   16755篇
  2014年   23092篇
  2013年   35710篇
  2012年   49390篇
  2011年   52200篇
  2010年   30097篇
  2009年   27768篇
  2008年   47850篇
  2007年   50742篇
  2006年   50641篇
  2005年   49215篇
  2004年   47056篇
  2003年   44703篇
  2002年   43440篇
  2001年   61648篇
  2000年   63143篇
  1999年   53084篇
  1998年   15692篇
  1997年   14267篇
  1996年   13914篇
  1995年   13269篇
  1994年   12347篇
  1993年   11557篇
  1992年   42110篇
  1991年   41279篇
  1990年   39896篇
  1989年   37828篇
  1988年   35012篇
  1987年   34133篇
  1986年   32598篇
  1985年   31110篇
  1984年   23666篇
  1983年   20271篇
  1982年   12588篇
  1981年   11079篇
  1979年   21228篇
  1978年   15300篇
  1977年   12594篇
  1976年   12329篇
  1975年   12537篇
  1974年   15137篇
  1973年   14802篇
  1972年   13616篇
  1971年   12606篇
  1970年   11684篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
OBJECTIVES: CD62L was evaluated as a determinant of human pre-effector T cells. STUDY DESIGN AND SETTING: Phenotype and cytokine secretion profiles of CD62L cells were determined based on activation status. RESULTS: CD62L(Low) T cells demonstrated significantly higher secretion of interleukin (IL)-10 and interferon (IFN)-gamma than did CD62L(High) T cells. After activation, the majority of cells expressed high levels of the CD62L surface marker. Postactivation levels of IL-10 production remained elevated or unchanged. In a murine B16 melanoma model, freshly isolated CD62L(Low) tumor draining lymph nodes (TDLN) T cells showed increased secretion of IL-2 and IL-4 but not of IL-10 or IFN-gamma. The surface expression of CD62L and cytokine secretion patterns were maintained after activation with concomitant increases in IL-10. CONCLUSION: Our results provide evidence that CD62L(Low) T cells in TDLNs of progressively growing squamous cell carcinoma of the head and neck differ phenotypically and functionally from those of mouse origin. SIGNIFICANCE: Characterization of this human CD62L(Low) T cell population provides initial insight regarding novel surface markers in TDLN T cells that might correlate with antitumor reactivity.  相似文献   
992.
Scurvy is a nondiscriminatory disease process resulting from a nutritional deficiency of ascorbic acid (vitamin C). The severe vitamin deficiency produces a breakdown in the cellular structure of the body. This case report describes a middle-age woman with a history of edema, bruising of the lower extremities, anemia, and severe periodontal disease. Her presentation and medical history are classic for the signs of scurvy. Scurvy is now only uncommonly seen in developed countries, but there are still vulnerable populations whose nutritional status can lead to scurvy. The aim of this report is to help the clinician identify and treat scurvy, a disease that was once feared for its high mortality but is now easily treatable, even in cases that have progressed to multiple organ dysfunction and failure.  相似文献   
993.
Extrahepatic portal vein thrombosis (EHPVT) may occur in children or adults and usually comes to clinical attention due to complications of portal hypertension such as variceal hemorrhage. A variety of standard surgical techniques exist to manage these patients, but when these fail surgical options are limited. We describe two novel portosystemic shunts that utilize the gonadal vein as an autologous conduit. Four patients were evaluated for EHPVT with variceal bleeding. None of the patients were candidates for a standard splenorenal shunt due to prior surgical procedures. The first patient underwent a left mesogonadal shunt and the remaining 3 patients underwent a right mesogonadal shunt. Postoperative ultrasound or computed tomography (CT) scan confirmed early patency of the shunt in each patient. There have been no further episodes of variceal hemorrhage with follow-up of 3.5 years in the child who underwent the left mesogonadal shunt, and 17, 19, and 20 months in the patients who underwent the right mesogonadal shunt. Three of the 4 shunts remain patent. One shunt thrombosis occurred in a patient homozygous for the Factor V Leiden mutation despite anticoagulation with coumadin. This is the first report of the successful use of the gonadal vein as an in situ conduit for constructing a portosystemic shunt. In conclusion, the right and left mesogonadal shunts may be useful as salvage operations for patients with EHPVT who have failed standard surgical shunt procedures.  相似文献   
994.
995.
Although lesions of the pterygopalatine space are uncommon, there are instances in which this relatively inaccessible region must be entered for biopsy or excision of masses. Traditional open approaches to the pterygopalatine space, involving external or intraoral incisions, provide limited visualization and carry associated morbidities. The evolution and advancement of endoscopic sinus surgical technique in recent years has led to its application to anatomic areas outside the strict limits of the sinonasal cavities. Such minimally invasive approaches are safe, effective, and spare unnecessary discomfort to the patient. This article describes the authors' method for performing an endoscopic approach to the pterygopalatine space.  相似文献   
996.
The study of the cognitive abilities of hearing-impaired children is important for both practical (e.g. to determine appropriate teaching strategies) and theoretical reasons (e.g. to examine the role of language in thought processes). The aim of this paper is to examine the cognitive function of hearing-impaired children from a review of the literature. If most studies show that deaf children are similar to normal children in virtually all aspects of cognitive function, many studies also emphasize pronounced differences in their academic achievement. Besides the degree of hearing loss and the age at onset of deafness, environmental factors (such as parental support and educational methods) seem to play an important role in the cognitive development and academic success of these children. This underlines the importance of the measures adopted for the deaf children as they may have a positive or negative impact on their development.  相似文献   
997.
Wodtke  J.  Kl&#;ber  D.  Frommelt  L.  L&#;hr  J. F. 《Trauma und Berufskrankheit》2005,7(1):S134-S138
Trauma und Berufskrankheit - Als schwerste Komplikation der Gelenkendoprothetik bleibt die periprothetische Infektion eine Herausforderung—heutzutage nicht nur für den Chirurgen, sondern...  相似文献   
998.
Occupational diseases Nos. 2108 and 2110 correspond to intervertebral disc-related diseases of the lumbar spine from many years of carrying or lifting heavy loads, occupations in extreme postures of full flexion or oscillation of the whole body when seated, and which compel the cessation of all activities which are or could be the cause for the origin, exacerbation or recurrence of the disease. These occupational diseases came into force at the start of 1993, but there have been considerable problems in their implementation. The present Part I of the contribution is the result of the work of an interdisciplinary study group and contains medical criteria for the assessment of possibly strain-related clinical characteristics and the evaluation of other possible causes. Part II is to be published in Volume 4/2005 and will deal with questions related to forced cessation and to the assessment of the loss of earning ability. Agreement was reached in many areas related to the assessment of occupational claims. This should allow for evidence-based decision making in the future for the occupational diseases Nos. 2108 and 2110.  相似文献   
999.
Multidetector-row computed tomography (MDCT) can be used to quantify morphological features and investigate structure/function relationship in COPD. This approach allows a phenotypical definition of COPD patients, and might improve our understanding of disease pathogenesis and suggest new therapeutical options. In recent years, magnetic resonance imaging (MRI) has also become potentially suitable for the assessment of ventilation, perfusion and respiratory mechanics. This review focuses on the established clinical applications of CT, and novel CT and MRI techniques, which may prove valuable in evaluating the structural and functional damage in COPD.  相似文献   
1000.
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