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   5451篇
  免费   617篇
  国内免费   168篇
耳鼻咽喉   56篇
儿科学   220篇
妇产科学   135篇
基础医学   118篇
口腔科学   79篇
临床医学   1220篇
内科学   1230篇
皮肤病学   162篇
神经病学   313篇
特种医学   188篇
外科学   1589篇
综合类   13篇
预防医学   323篇
眼科学   325篇
药学   41篇
肿瘤学   224篇
  2023年   106篇
  2021年   65篇
  2020年   95篇
  2019年   51篇
  2018年   126篇
  2017年   173篇
  2016年   191篇
  2015年   143篇
  2014年   226篇
  2013年   299篇
  2012年   95篇
  2011年   112篇
  2010年   225篇
  2009年   336篇
  2008年   119篇
  2007年   68篇
  2006年   97篇
  2005年   67篇
  2003年   49篇
  2002年   37篇
  2001年   103篇
  2000年   65篇
  1999年   128篇
  1998年   175篇
  1997年   199篇
  1996年   301篇
  1995年   255篇
  1994年   195篇
  1993年   115篇
  1992年   124篇
  1991年   139篇
  1990年   68篇
  1989年   131篇
  1988年   107篇
  1987年   82篇
  1986年   101篇
  1985年   86篇
  1984年   88篇
  1983年   76篇
  1982年   68篇
  1981年   64篇
  1980年   81篇
  1979年   41篇
  1978年   59篇
  1977年   43篇
  1976年   43篇
  1975年   45篇
  1972年   36篇
  1964年   49篇
  1963年   47篇
排序方式: 共有6236条查询结果,搜索用时 13 毫秒
61.
Our aim was to examine the feasibility of a totally laparoscopic insertion of a bifurcated aortofemoral bypass graft in a canine model and to compare the surgical results with those in control animals undergoing standard grafting and laparoscopic-assisted bypass procedures. Using a six-port approach, we exposed and cross clamped the aorta, tunneled a bifurcated Dacron graft, and performed an end-to-end aortic anastomosis while maintaining pneumoperitoneum by means of CO2. Proximal anastomoses were performed with 4/0 double-ended continuous Prolene sutures and distal anastomoses were performed through standard groin incisions. Total operating and aortic cross-clamp times were measured as was the total blood loss for each procedure. Clinical outcome was also documented. Eight female laboratory-bred hounds underwent successful totally laparoscopic aortobifemoral bypass grafting, eight underwent open grafting, and eight underwent laparoscopic-assisted bypass. Mean operating time was 193 minutes in the animals undergoing totally laparoscopic insertion vs. 156 minutes in the open group and 180 minutes in the laparoscopic-assisted group. Aortic cross-clamping time was also significantly longer at 87 minutes vs. 43 minutes (p < 0.001)=" in=" the=" totally=" laparoscopic=" group,=" but=" blood=" loss=" was=" less.=" all=" eight=" laparotomy=" and=" laparoscopic-assisted=" dogs=" were=" still=" alive=" with=" no=" complications=" at=" 28=" days,=" whereas=" three=" of=" the=" eight=" in=" the=" totally=" laparoscopic=" group=" showed=" evidence=" of=" temporary=" paraplegia.=" this=" experimental=" study=" demonstrates=" that=" a=" totally=" laparoscopic=" approach=" can=" be=" used=" to=" insert=" a=" bifurcated=" aortofemoral=" bypass=" with=" a=" proximal=" end-to-end=" anastomosis=" but=" currently=" does=" not=" save=" time=" and=" may=" increase=" the=" risk=" of=" neurologic=">Presented at the Twentieth Annual Meeting of the Peripheral Vascular Surgery Society, New Orleans, La., June 10, 1995.  相似文献   
62.
The success of vertical gastroplasty may be jeopardized by gastric leakage or ulceration due to failure of the technique. Reports of band erosion and staple-line leakage have led us to seek technical improvements to reduce technical failures. We describe a modification to the technique of band placement and a manoeuvre to aid the placement of staples when the TA90 staple gun is used.  相似文献   
63.
Many forms of gastric banding have been described and high reoperation rates reported. These can be mainly attributed to excess vomiting associated both with and without stenosis. Reflux oesophagitis and the ‘sump’ effect may be other causes. This paper examines the problems associated with banding leading to revisional surgery and introduces a new technique, ‘fundal supporting suture’, to correct these problems. Preliminary results on 126 bandings without the modification and 22 with the modification are presented.  相似文献   
64.
Increased placental apoptosis in intrauterine growth restriction   总被引:2,自引:0,他引:2  
OBJECTIVES: Our purpose was to investigate a possible role for apoptosis in the pathophysiologic mechanisms of intrauterine growth restriction. STUDY DESIGN: Placental samples were obtained from 43 uncomplicated third-trimester pregnancies and from 26 pregnancies complicated by intrauterine growth restriction. The definition used to identify cases of intrauterine growth restriction depended on three criteria: clinical evidence of suboptimal growth, ultrasonographic evidence of deviation from an appropriate growth percentile, and individualized birth weight ratios <10th percentile. Light microscopy was used to quantify the incidence of apoptosis. Electron microscopy and TUNEL (terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick end labeling) staining were used to confirm the occurrence of apoptosis. RESULTS: Quantification of apoptosis (medians and interquartile ranges) resulted in the following values: normal third trimester (n = 43) 0.14% of cells (0.08% to 0.20%) and intrauterine growth restriction third trimester (n  = 26) 0.24% of cells (0.16% to 0.29%). The incidence of apoptosis was significantly higher in placentas from pregnancies with intrauterine growth restriction compared with normal third-trimester placentas (p < 0.01, Mann Whitney U test). CONCLUSIONS: These results suggest that apoptosis may play a role in the pathophysiologic mechanisms of intrauterine growth restriction.(Am J Obstet Gynecol 1997;177:401)  相似文献   
65.
66.
Exophthalmometry, the quantitative assessment of the position of the globe in the orbit, is a clinically useful measurement. The purpose of this study was to examine the performance of a simple exophthal-mometer that would lend itself to accurate and convenient use in clinical practice. In this study, two observers independently performed exophthalmometry on 100 eyes using the Hertel and Luedde instruments. The results were compared between instruments and between observers. There was no statistically or clinically significant difference between measurements taken with the Luedde as compared with the Hertel instrument. The Luedde exophthal-mometer has a number of advantages over the Hertel exophthalmometer, and represents a simple, inexpensive and equally reliable means of evaluating clinically the anteroposterior position of the eye in the orbit.  相似文献   
67.
A TEN-YEAR HOSPITAL SURVEY OF EYELID CANCER   总被引:1,自引:0,他引:1  
Two hundred and four cases of malignant eyelid tumours, managed at the Concord Hospital, were reviewed. These cases spanned a ten-year period between 1973 and 1982 and all were treated surgically. The nature of each tumour was confirmed by histopathological examination. Included in this review were the site of the tumour, the tumour pathology, the surgical management, the type of surgeon involved, the ocular complications, the management of recurrences and any mortality. The importance of preventing recurrences by adequate initial surgery with frozen section control is emphasized.  相似文献   
68.
Multiple myeloma (MM) is an incurable hematologic neoplasm, whose poor prognosis is deeply affected by the propensity of tumor cells to localize in the bone marrow (BM) and induce the protumorigenic activity of normal BM cells, leading to events associated with tumor progression, including tumor angiogenesis, osteoclastogenesis, and the spread of osteolytic bone lesions. The interplay between MM cells and the BM niche does not only rely on direct cell-cell interaction, but a crucial role is also played by MM-derived extracellular vesicles (MM-EV). Here, we demonstrated that the oncogenic NOTCH receptors are part of MM-EV cargo and play a key role in EV protumorigenic ability. We used in vitro and in vivo models to investigate the role of EV-derived NOTCH2 in stimulating the protumorigenic behavior of endothelial cells and osteoclast progenitors. Importantly, MM-EV can transfer NOTCH2 between distant cells and increase NOTCH signaling in target cells. MM-EV stimulation increases endothelial cell angiogenic ability and osteoclast differentiation in a NOTCH2-dependent way. Indeed, interfering with NOTCH2 expression in MM cells may decrease the amount of NOTCH2 also in MM-EV and affect their angiogenic and osteoclastogenic potential. Finally, we demonstrated that the pharmacologic blockade of NOTCH activation by γ-secretase inhibitors may hamper the biological effect of EV derived by MM cell lines and by the BM of MM patients. These results provide the first evidence that targeting the NOTCH pathway may be a valid therapeutic strategy to hamper the protumorigenic role of EV in MM as well as other tumors.  相似文献   
69.
70.
To the Editor: There are a large number of studies addressing the impact of continuing medical education (Davis et al. 1995) and clinical guidelines (Grimshaw & Russell 1993) on changing clinical practice, but comparatively little on the impact of purchasers of health care. There is some evidence that financial incentives and penalties can influence practice (Greco & Eisenberg 1993). It has been suggested that purchasers can play an important role in implementing research findings (Haines & Jones 1994). Indeed, the separation of purchasers and providers has been viewed as an opportunity to use knowledge about effectiveness to improve health services (Dunning et al. 1994). We report a study the aim of which was to explore the impact that a specific brief external intervention might have on a detailed aspect of clinical practice: the use of corticosteroids in preterm labour. The intervention was initiated by public health physicians on behalf of a Health Authority. It formed a part of the Getting Research Into Practice (GRIP) initiative in the old Oxford Health Region, UK.  The administration of corticosteroids to mothers expected to deliver prematurely reduces neonatal mortality and morbidity (Crowley et al. 1990). The first trial which suggested that corticosteroids were effective in this role was published in 1972, and evidence from 12 trials was assembled in a systematic review published in January 1990 (Crowley et al. 1990). Despite the accumulating evidence, in 1991 many women delivering prematurely in the UK and elsewhere were not receiving corticosteroids (Anon 1992;Donaldson 1992). The apparent failure of obstetricians to make full use of this treatment has been cited as an example of the delayed implementation of research findings that can occur in clinical practice (Haines & Jones 1994; Enkin 1996).  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