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   25778篇
  免费   1315篇
  国内免费   174篇
耳鼻咽喉   198篇
儿科学   528篇
妇产科学   444篇
基础医学   2831篇
口腔科学   618篇
临床医学   2058篇
内科学   6759篇
皮肤病学   488篇
神经病学   2987篇
特种医学   779篇
外科学   3898篇
综合类   45篇
一般理论   5篇
预防医学   1089篇
眼科学   475篇
药学   1462篇
中国医学   30篇
肿瘤学   2573篇
  2024年   15篇
  2023年   164篇
  2022年   328篇
  2021年   751篇
  2020年   450篇
  2019年   622篇
  2018年   698篇
  2017年   553篇
  2016年   624篇
  2015年   696篇
  2014年   1015篇
  2013年   1276篇
  2012年   2005篇
  2011年   1995篇
  2010年   1161篇
  2009年   1073篇
  2008年   1748篇
  2007年   1810篇
  2006年   1672篇
  2005年   1650篇
  2004年   1630篇
  2003年   1354篇
  2002年   1320篇
  2001年   190篇
  2000年   119篇
  1999年   149篇
  1998年   250篇
  1997年   213篇
  1996年   196篇
  1995年   176篇
  1994年   131篇
  1993年   132篇
  1992年   118篇
  1991年   93篇
  1990年   91篇
  1989年   68篇
  1988年   70篇
  1987年   67篇
  1986年   59篇
  1985年   60篇
  1984年   79篇
  1983年   46篇
  1982年   46篇
  1981年   44篇
  1980年   33篇
  1979年   25篇
  1978年   17篇
  1977年   31篇
  1976年   19篇
  1974年   16篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Embryonic remnants of incomplete septation may complicate occlusiondevice implantation in secundum atrial septal defects (sASD)even if stiff devices such as the Amplatzer Occluder are used. A 35-year-old woman was referred to our center for evaluationof a sASD.  相似文献   
82.
BACKGROUND: The impact of short-term preoperative pulmonary rehabilitation on exercise capacity of patients with chronic obstructive pulmonary disease undergoing lobectomy for non-small cell lung cancer is evaluated. METHODS: A prospective observational study was designed. Inclusion criteria consisted of an indication to lung resection because of a clinical stage I or II non-small cell lung cancer and a chronic obstructive disease on preoperative pulmonary function test. In such conditions, maximal oxygen consumption by a cardio-pulmonary exercise test was evaluated; when this resulted as being < or =15 ml/kg/min a pulmonary rehabilitation programme lasting 4 weeks was considered. Twelve patients fulfilled inclusion criteria, completed the preoperative rehabilitation programme and underwent a new functional evaluation prior to surgery. The postoperative record of these patients was collected. RESULTS: On completion of pulmonary rehabilitation, the resting pulmonary function test and diffuse lung capacity of patients was unchanged, whereas the exercise performance was found to have significantly improved; the mean increase in maximal oxygen consumption proved to be at 2.8 ml/kg/min (p<0.01). Eleven patients underwent lobectomy; no postoperative mortality was noted and mean hospital stay was 17 days. Postoperative pulmonary complication was recorded in 8 patients. CONCLUSIONS: Short-term preoperative pulmonary rehabilitation could improve the exercise capacity of patients with chronic obstructive pulmonary disease who are candidates for lung resection for non-small cell lung cancer.  相似文献   
83.
To date, few studies have examined the personality characteristics and clinical predictors of impulsive behaviors in eating disorders (ED). The aim of this work was to study the prevalence of a wide range of impulsive behaviors in a sample of 554 ED subjects and to examine the predictors of these behaviors. Subjects were diagnosed according to DSM-IV criteria as having anorexia nervosa restricting type (ANR; n = 183), anorexia nervosa binge eating/purging type (ANBP; n = 65), bulimia nervosa purging type (BNP; n = 244), and bulimia nervosa nonpurging type (BNNP; n = 62). Nine different types of impulsive behaviors were assessed in these groups. About 55% of the whole sample reported at least one type of impulsive behavior, 35% more than one, and about 13% more than three. According to findings, impulsive and multi-impulsive subjects are characterized by the presence of purging behavior and by specific temperamental features such as high levels of novelty seeking and low persistence. The prediction of impulsive behavior is further improved by considering the presence of a history of childhood abuse, maternal psychiatric morbidity, and some specific psychological symptoms such as maturity fears, perfectionism, depression, and obsessive-compulsive symptoms. The presence of impulsive behavior appears to be associated with overall higher levels of psychiatric symptomatology and eating psychopathology, thus indicating that they are an important feature to be considered in the assessment and treatment of ED.  相似文献   
84.
85.
86.
The Pediatric End-Stage Liver Disease (PELD) score was designed to reduce subjectivity in liver allocation and to advantage patients with a higher probability of waiting list mortality. The aims of this study were to determine the impact of PELD implementation for children with chronic liver disease and to assess whether PELD met its goal of standardization of liver allocation for children. This study used data reported to the United Network for Organ Sharing (UNOS) registry for children with chronic liver disease receiving primary cadaveric liver transplant between January 2000 and December 2001 (pre-PELD) and March 2002 and July 2003 (PELD). PELD reduced the percentage of children transplanted while in an intensive care unit and as status 1. A calculated PELD score was used for allocation in only 52% of recipients. Thirty percent were status 1 at transplant and PELD scores granted by exception were used for allocation in 18% of patients. There was regional variation in PELD score at allocation and use of exception scores with a significant relationship between PELD score and percentage of exception cases. Regional variation suggests that PELD has not resulted in standardization of listing practices in pediatric liver transplantation.  相似文献   
87.
88.
Using a corticostriatal slice preparation, we have recently shown that tetanic stimulation of the corticostriatal pathway produces long-term depression (LTD) of striatal excitatory synaptic transmission. In the present study we have analysed the relationship between LTD and the striatal release of different endogenous transmitters. Samples of perfusate were collected via a small cannula placed just above the surface of the striatal slice close to the recording electrode, and were analysed by HPLC. The high-frequency stimulation (100 Hz, three trains, 3 s duration, 20 s intervals) used to induce LTD caused a significant but transient increase in the release of both excitatory (aspartate and glutamate) and inhibitory (glycine and GABA) amino acid transmitters. Tetanic stimulation also produced a significant, but transient increase in the release of endogenous dopamine. We conclude that the tetanic stimulation of the corticostriatal pathway is able to induce a large but transient release of excitatory amino acids and of dopamine, whose participation in the induction of striatal LTD has been demonstrated previously. Moreover, the maintenance of this form of synaptic plasticity does not seem to require a sustained change in transmitter release.  相似文献   
89.
In this contribution, the X-ray diffraction (XRD) pattern of a highly oriented sample of syndiotactic polystyrene in the mesomorphic form, collected by an automatic diffractometer, is presented, thus providing quantitative and more complete information relative to the diffracted intensity. The structural changes induced by annealing procedures in mesomorphic samples are shown through the analysis of the XRD patterns: both unoriented and oriented mesomorphic samples are transformed gradually into α-form crystals. On the basis of these evidences and of preliminary comparisons between the calculated Fourier transform of simplified models and the experimental diffraction intensity, it is suggested that the local organization in triplets of trans-planar chains, typical of the different modifications of the α-form, would be largely present also in the disordered chain agglomerates of the mesomorphic form.  相似文献   
90.
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