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   19946篇
  免费   1238篇
  国内免费   37篇
耳鼻咽喉   120篇
儿科学   694篇
妇产科学   709篇
基础医学   2696篇
口腔科学   264篇
临床医学   3327篇
内科学   3713篇
皮肤病学   204篇
神经病学   1986篇
特种医学   293篇
外科学   1438篇
综合类   256篇
一般理论   31篇
预防医学   2820篇
眼科学   151篇
药学   1164篇
中国医学   13篇
肿瘤学   1342篇
  2023年   89篇
  2022年   161篇
  2021年   340篇
  2020年   212篇
  2019年   377篇
  2018年   393篇
  2017年   281篇
  2016年   356篇
  2015年   405篇
  2014年   602篇
  2013年   964篇
  2012年   1385篇
  2011年   1389篇
  2010年   768篇
  2009年   755篇
  2008年   1357篇
  2007年   1339篇
  2006年   1335篇
  2005年   1368篇
  2004年   1306篇
  2003年   1282篇
  2002年   1243篇
  2001年   154篇
  2000年   134篇
  1999年   171篇
  1998年   253篇
  1997年   220篇
  1996年   183篇
  1995年   191篇
  1994年   170篇
  1993年   166篇
  1992年   139篇
  1991年   118篇
  1990年   108篇
  1989年   110篇
  1988年   105篇
  1987年   107篇
  1986年   77篇
  1985年   82篇
  1984年   118篇
  1983年   89篇
  1982年   125篇
  1981年   104篇
  1980年   106篇
  1979年   58篇
  1978年   67篇
  1977年   43篇
  1976年   50篇
  1975年   34篇
  1974年   42篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Post-transplant bronchiolitis obliterans (BO) is characterized by fibroproliferation and fibrous obliteration of distal airways in chronically rejected lungs. In this study, using a rat heterotopic allogeneic tracheal transplant model of BO, we evaluated the expression of transforming growth factor-beta (TGFbeta) during the development of airway fibrous obliteration. Immunohistochemical analysis revealed TGFbeta staining in infiltrating mononuclear cells at Days 2 and 7, and in the fibrous tissues until Day 21. Soluble TGFbeta receptor type III (TGFBIIIR), by blocking TGFbeta binding to its membrane receptors, functions as a TGFbeta antagonist. To study the role of TGFbeta in the development of BO, adenoviral-mediated soluble TGFBIIIR gene transfection (5 x 10(9) particles) was performed topically at the site of transplant on Day 5 after transplantation, which leads to inhibition of fibrous airway obliteration. In contrast, empty vector gene delivered through intramuscular injection, or given locally at Days 0 or 10 after tracheal transplantation had no significant effect. These results suggest that TGFbeta expressed in the allografts plays a pivotal role in the pathogenesis of BO. Soluble TGFBIIIR may competitively inhibit TGFbeta activity locally. Adenoviral-mediated soluble TGFBIIIR gene transfection should be further explored as a potential therapeutic modality for BO and other conditions involving chronic fibrosis.  相似文献   
992.
Considerable efforts are underway to define effective strategies for the treatment of metabolic complications of HIV therapy. Clearly these problems dominate the overall approach to treatment of HIV infection in the settings where antiretroviral agents are accessible. While progress has been made it has been slow, and accompanied by disappointments. There are currently no effective treatments for lipoatrophy, and while treatments for dyslipidemia have been described, in most cases the improvement is incomplete. While these efforts must continue it is hoped that a new focus on prevention of metabolic complications will begin to emerge in the year ahead.  相似文献   
993.
OBJECTIVES: Murine erythroblasts infected with the anemia-inducing strain of Friend virus (FVA cells) terminally differentiate to the reticulocyte stage after 48 hours of culture in vitro in response to erythropoietin (EPO). The objective of this study was to determine the possible role of proteasome-mediated proteolysis during the terminal differentiation of FVA cells. MATERIALS AND METHODS: The proteasome inhibitors MG132 and lactacystin were used to perturb the normal function of proteasomes during terminal differentiation. Effects of proteasome inhibitors on terminal differentiation were quantitated by evaluation of cellular morphology after benzidine staining and by Western blot analyses. RESULTS: Treatment of EPO-stimulated FVA cells with lactacystin or MG132 at later periods of culture increased accumulations of nuclear and cytosolic ubiquitinated proteins and decreased nuclear extrusion to less than 40% of controls. CONCLUSIONS: Our results suggest that the proteasomal degradation of ubiquitinated proteins plays an important role in the enucleation of mammalian erythroblasts.  相似文献   
994.
995.
Guidance of percutaneous pulmonary biopsies with real-time CT fluoroscopy   总被引:5,自引:0,他引:5  
OBJECTIVE: Clinical evaluation of computed tomography (CT) fluoroscopy and comparison with conventional CT guidance for monitoring of percutaneous pulmonary biopsy procedures. METHODS: Twenty CT-guided pulmonary biopsy procedures were conducted. The interventions have prospectively been performed either with CT fluoroscopy or with conventional CT guidance. About 120 kV and 50 mA with a frame-rate of eight images per second were used for CT fluoroscopy. Number of pleural needle passages, procedure times, radiation doses and histologic results were analyzed separately for both methods. RESULTS: Compared with conventional CT guidance, CT fluoroscopy was associated with less pleural needle passages (1.8+/-0.6 vs. 1.1+/-0.3; P=0.003, t-test) and procedure times were shorter than for conventional CT guidance (12.7+/-2.2 min vs. 26.7+/-16.4 min; P=0.02). Analysis of estimated patient related radiation exposure and histologic outcome showed no significant difference between conventional and fluoroscopic CT-guided procedures (P>0.05). CONCLUSION: CT fluoroscopy facilitates guidance of percutaneous pulmonary biopsy procedures. Compared with conventional CT assistance, procedure times are decreased and less pleural needle passages are required. While patient-related radiation exposure is similar, operator-related radiation exposure remains a disadvantage associated with CT fluoroscopy.  相似文献   
996.
This short case report presents the development and treatment of a head lice outbreak during a space simulation experiment. The confinement experiment was conducted from July 1999 to March 2000 at the State Research Center of the Russian Federation Institute for Biomedical Problems in Moscow. Following a symptom period of up to 9 wk before diagnosis and treatment, 3 wk of treatment were required to remove all nits from those infected. Recommendations are made with regard to prevention of such infections during space missions. Treatment altered performance and comfort of crews, took time out of other duties, and even affected relations between crewmembers. The case is made for the development of a public health agenda in space research and medical space programs.  相似文献   
997.
BACKGROUND: To determine the effect on margin evaluation for patients with breast cancer, we prospectively quantified the "flattening" of the breast specimen after surgical removal. METHODS: The volume and height of 100 consecutive breast biopsy specimens were recorded independently by the operating surgeon and the pathologist. Five factors were analyzed that were thought to contribute to changes in specimen dimensions: patient age, breast tissue density, mammographic lesion type, specimen size, and the use of compression during specimen radiography. RESULTS: After surgical removal, mean volume and height of the breast specimens decreased from 46 cm(3) to 29 cm(3) (30%) and from 2.6 cm to 1.4 cm (46%), respectively. Flattening of the breast specimens occurred in all subgroups studied. CONCLUSIONS: Breast specimens are flattened after surgical removal, losing almost 50% of their original height. This "pancake" phenomenon has important implications for the accuracy of margin analysis.  相似文献   
998.
A posterior vaginal wall prolapse, also known as a rectocele, is a common condition and is an outpouching of the posterior vaginal wall and anterior rectal wall into the lumen of the vagina.1-5 Although more common in parous women, rectoceles of over 1 cm in size have been demonstrated in over 40% of nulliparous women. As rectoceles may be asymptomatic, their true prevalence is not clear. Many women with rectoceles present to their gynaecologist who may not ascertain any anorectal symptoms or perform a rectal examination. Conversely, colorectal surgeons often disregard a vaginal examination.6 Conventionally, gynaecologists have managed rectoceles, but increasingly colorectal surgeons are involved because of the prevalence of anorectal symptoms. There are many surgical techniques for the management of a symptomatic rectocele. There is, however, little data to suggest which is the most effective technique, or whether specific techniques are more appropriate in certain circumstances.7  相似文献   
999.
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