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   3818篇
  免费   413篇
  国内免费   14篇
耳鼻咽喉   43篇
儿科学   236篇
妇产科学   34篇
基础医学   539篇
口腔科学   122篇
临床医学   441篇
内科学   763篇
皮肤病学   42篇
神经病学   218篇
特种医学   189篇
外科学   420篇
综合类   79篇
一般理论   2篇
预防医学   513篇
眼科学   45篇
药学   352篇
中国医学   2篇
肿瘤学   205篇
  2022年   26篇
  2021年   56篇
  2019年   56篇
  2018年   69篇
  2017年   53篇
  2016年   52篇
  2015年   68篇
  2014年   100篇
  2013年   136篇
  2012年   149篇
  2011年   154篇
  2010年   136篇
  2009年   103篇
  2008年   146篇
  2007年   173篇
  2006年   156篇
  2005年   129篇
  2004年   141篇
  2003年   129篇
  2002年   130篇
  2001年   107篇
  2000年   117篇
  1999年   135篇
  1998年   93篇
  1997年   68篇
  1996年   72篇
  1995年   66篇
  1994年   72篇
  1993年   49篇
  1992年   98篇
  1991年   104篇
  1990年   101篇
  1989年   78篇
  1988年   86篇
  1987年   77篇
  1986年   65篇
  1985年   61篇
  1984年   42篇
  1983年   46篇
  1982年   38篇
  1981年   30篇
  1979年   36篇
  1978年   29篇
  1977年   36篇
  1976年   36篇
  1975年   26篇
  1974年   37篇
  1973年   37篇
  1972年   30篇
  1970年   27篇
排序方式: 共有4245条查询结果,搜索用时 15 毫秒
1.
While once considered as incurable systemic disease, treatment options for liver metastases have increased over the last 30 years and safety has improved dramatically, such that for a selected group of patients the hope of cure can now be offered with radical treatment, and low morbidity interventions can be offered which prolong survival, even in patients with more widely disseminated disease. Advances have been made in selection and surgical technique for liver resection and several adjuncts to resection now exist in the form of portal vein embolization, thermal ablation and targeted drug or radiotherapy delivery options. A natural consequence of these developments has been the delivery of services within fewer specialist units, with the result that later complications of therapy may present to local hospitals, rather than directly to the specialist centres. This article will describe the current common liver-directed therapies and outline the presentation and management of their complications.  相似文献   
2.
BACKGROUND: Repairing dorsal nasal defects is a frequent challenge for dermatologic surgeons, mainly due to the high frequency of basal cell carcinomas on this site. Obvious scars, mismatched skin and distortion of the nasal contour are the surgical hazards that must be avoided in these cases. AIM: Our aim was to perform surgery involving a simple flap in order to repair medium to large defects on the dorsal side of the nose. METHODS: The dorsal horizontal advancement flap was studied in 12 patients, in order to evaluate the benefits and limits of this surgical procedure. RESULTS: The resulting scars on most of our patients were well-camouflaged among their natural skin lines, and there was neither distortion of the alar contour nor the nostril. CONCLUSIONS: This flap is easy to perform and, in selected cases, provides an outstanding alternative to second-intention healing, full-thickness skin grafts, transposition, rotation and pedicle flaps.  相似文献   
3.
A K Carruth  D Booth 《AAOHN journal》1991,39(9):427-431
Future trends include a decrease in the number of adult children, an increase in the number of individuals over age 65, single parent families, working women, and individuals with no health care insurance. As more women with multiple roles and responsibilities enter and continue as part of the work force, employers recognize the need for support of family issues. Currently many employers lack initiative to make these needed changes. The occupational health nurses' role in relation to future policy for working caregivers includes assessment of how employment and caregiving impact work performance, job satisfaction, and health; and participation in defining public policy issues.  相似文献   
4.
Purpose To demonstrate that laparoscopic adjustable gastric banding may promote oesophageal dilatation or interfere with oesophageal motility. Methodology We report a case of a 67 year old female with a complex medical history who developed secondary achalasia from a slipped laparoscopic adjustable gastric band for weight loss. This led to recurring episodes of aspiration pneumonia requiring multiple admissions at North Shore Hospital, Auckland, New Zealand. Results A decision was made to remove the gastric band, five years after its initial insertion. At one month follow up, she was swallowing normally and oesophageal manometry had returned to normal. Conclusion Oesophageal dysmotility is sometimes seen in patients who have bands that are adjusted too tightly or in whom the band has slipped. This can lead to serious complications if unrecognized and incorrectly treated. Oesophageal symptoms in patients with adjustable bands must be considered secondary to the band until proven otherwise ie removal of the band or complete deflation.  相似文献   
5.
Paul L. Booth  W. Eric Thomas   《Brain research》1991,548(1-2):163-171
Ramified microglial cells were investigated in primary cultures of dissociated cerebral cortical tissue from rats. The identification of these cells was confirmed through immunohistochemical staining with 7 monoclonal antibodies selective for microglia. While there was significant variation in staining intensity with different antibodies, all stained the identified ramified cells; the antibodies OX-42 and ED1 yielded the most intense immunoreactivity. Based on distinctive morphological features, the microglia could be identified in living cultures where they were monitored using time-lapse video recording. This technique revealed extremely dynamic features of cellular plasticity and motility. Ramified microglia exhibited constant and rapid alterations in the size and shape of their cell body with an associated extension and retraction of processes; concomitantly, the cells moved about in a circumscribed area. These features of plasticity and motility were unique to this cell type, and correlated with OX-42 immunostaining. The microglia also possessed a differentially high level of pinocytotic activity; this too was correlated with OX-42 staining. From the nature of their morphological plasticity and motility, high pinocytosis, and cellular distribution, it is hypothesized that the ramified microglia specifically function as a system of fluid cleansing in normal brain tissue.  相似文献   
6.
A novel chiral redox-active ferrocene compound (FcVI) with amphiphilic properties has been synthesized. Cryogenic Transmission Electron Microscopy (cryo-TEM) has been used to estimate the shape and size of the FcVI aggregates in solution. Uni- and multi-lamellar vesicles (between 40 and 300 nm in diameter) were observed in water. Large particles (of more than 1 μm in diameter) with a hexagonal fine structure were found in 50 mM aqueous Na2SO4 solution. Sonication transformed the latter into ‘rosette’-like structures. Cyclic voltammetry has been employed to investigate the electrochemical properties of FcVI. The amphiphile adsorbed on graphite electrodes and a reversible electrochemical behaviour, characteristic of ferrocene, was observed with redox potentials between 330 and 350 mV.  相似文献   
7.
In a series of experiments in which Mongolian gerbils were trained to jump over a variable gap, it was demonstrated that computation of the distance to be jumped was dependent on both image size and retinal motion, the latter cue being generated by the production of vertical translation movements of the head (head bobs). When image size was not a reliable cue, the animals produced more head bobs, thereby increasing the availability of retinal motion cues. The performance of the gerbils on various probe trials strongly suggested that they computed absolute distance by combining information about the velocity (or amplitude) of their head bobs with information about the velocity (or displacement) of the moving image of the landing platform.  相似文献   
8.
9.
The concentration of mitochondria decrease in the heart as rodents age from maturity to senescence. The reason for this change is not known. One purpose of the present study was to determine if cytochrome c mRNA, representative of proteins of the inner mitochondrial membrane, decreased in the hearts of Fischer 344 rats as they aged from 12 to 24 months. Twenty-two percent less cytochrome c mRNA existed per given quantity of extracted RNA from the heart in 24-month-old rats as compared with the 12-month-old group. No change in the quantities of cardiac -actin mRNA, Ca2+/calmodulin protein kinase II mRNA or 18S rRNA was noted between 12- und 24-month-old hearts. Thus, the decrease in cytochrome c mRNA suggests that decreased in mRNAs for proteins of the inner mitochondrial membrane could play some role in the diminished concentration of mitochondria that exists in the senescent heart.  相似文献   
10.
Interventional balloon catheterisation is now the recommended procedure for several congenital heart defects. The overall complication rate in the first 160 children (median age 3 years) to undergo balloon intervention (excluding balloon atrial septostomy) at the Brompton Hospital was 24% (14% excluding haemorrhage and including three deaths (1.9%]. Most complications were related to vascular problems at the site of cardiac catheterisation. Complications were more common in the younger patient, especially neonates, and also in procedures that were ultimately unsuccessful. Most complications were transient and usually had no long term effects. Improvements in equipment design and technical expertise may reduce morbidity from these procedures.  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