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   5146篇
  免费   388篇
  国内免费   36篇
耳鼻咽喉   46篇
儿科学   128篇
妇产科学   139篇
基础医学   710篇
口腔科学   61篇
临床医学   717篇
内科学   872篇
皮肤病学   329篇
神经病学   502篇
特种医学   148篇
外科学   554篇
综合类   65篇
一般理论   6篇
预防医学   503篇
眼科学   166篇
药学   289篇
中国医学   9篇
肿瘤学   326篇
  2023年   42篇
  2022年   58篇
  2021年   126篇
  2020年   114篇
  2019年   127篇
  2018年   131篇
  2017年   106篇
  2016年   159篇
  2015年   121篇
  2014年   151篇
  2013年   237篇
  2012年   318篇
  2011年   351篇
  2010年   203篇
  2009年   179篇
  2008年   275篇
  2007年   302篇
  2006年   282篇
  2005年   298篇
  2004年   257篇
  2003年   311篇
  2002年   246篇
  2001年   87篇
  2000年   61篇
  1999年   66篇
  1998年   60篇
  1997年   51篇
  1996年   28篇
  1995年   47篇
  1994年   38篇
  1993年   33篇
  1992年   30篇
  1991年   17篇
  1990年   21篇
  1989年   21篇
  1988年   25篇
  1987年   27篇
  1986年   30篇
  1985年   32篇
  1984年   30篇
  1983年   25篇
  1982年   30篇
  1981年   31篇
  1980年   35篇
  1979年   34篇
  1978年   30篇
  1977年   24篇
  1976年   27篇
  1970年   16篇
  1966年   16篇
排序方式: 共有5570条查询结果,搜索用时 15 毫秒
71.
To determine whether MDR1 reversal by the addition of the P-glycoprotein (P-gp) inhibitor PSC-833 to standard induction chemotherapy would improve event-free survival (EFS), 419 untreated patients with acute myeloid leukemia (AML) aged 60 years and older were randomized to receive 2 induction cycles of daunorubicin and cytarabine with or without PSC-833. Patients in complete remission were then given 1 consolidation cycle without PSC-833. Neither complete response (CR) rate (54% versus 48%; P = .22), 5-year EFS (7% versus 8%; P = .53), disease-free survival (DFS; 13% versus 17%; P = .06) nor overall survival (OS; 10% in both arms; P = .52) were significantly improved in the PSC-833 arm. An integrated P-gp score (IPS) was determined based on P-gp function and P-gp expression in AML cells obtained prior to treatment. A higher IPS was associated with a significantly lower CR rate and worse EFS and OS. There was no significant interaction between IPS and treatment arm with respect to CR rate and survival, indicating also a lack of benefit of PSC-833 in P-gp-positive patients. The role of strategies aimed at inhibitory P-gp and other drug-resistance mechanisms continues to be defined in the treatment of patients with AML.  相似文献   
72.
In the following article, two of the increasingly important public health scientific disciplines of care for the elderly are compared under systematic aspects - gerontopsychiatry and nursing science - with the aim of determining the similarities and differences of both disciplines. There follows a discussion of social challenges facing the area of caring for the elderly suffering from psychiatric illnesses and the responsibilities which both disciplines have to cope with in the future. The clearing of the numerous existent geronto-psychiatric deficits in health care in Germany seems to be the main challenge.  相似文献   
73.
The present studies demonstrate that the murine adrenocortical tumor cell line Y-1 releases a digoxin-like immunoreactive material into both serum-supplemented nutrient medium and minimal Krebs-Ringer bicarbonate medium. Release of pregnenolone into minimal medium from these cells was consistently inhibited by addition of the cholesterol side-chain cleavage inhibitor aminoglutethimide. However, release of digoxin-like immunoreactivity (DLI) was not similarly affected. To exclude the possibility that DLI could be accounted for by cross-reaction with another known adrenal steroid, aminoglutethimide inhibition was accompanied by inhibition of 17 alpha-hydroxylase with SU-10603 and inhibition of 3 beta-hydroxysteroid dehydrogenase with cyanoketone. Once again, pregnenolone release was effectively inhibited, but no similar pattern of inhibition of DLI release was observed. Increasing the time of the incubation periods from 1 to 2 h did not change the pattern of secretion of pregnenolone or DLI. HPLC analysis of DLI released over prolonged culture periods into serum-supplemented nutrient medium showed high levels of DLI in a single major and several adjacent peaks. Analysis of the ability of extracts of Y-1-conditioned medium to compete with tritiated ouabain for binding to erythrocytes indicates that conditioned medium contained highly enriched levels of ouabain-like activity. On HPLC analysis, the distribution of this activity showed partial correlation with the distribution of DLI. These observations indicate that Y-1 cells produce and release significant quantities of a material with cardiac glycoside-like properties reflected in the cross-reactivity with antidigoxin antibodies and the ability to compete with ouabain for binding to erythrocytes. In substantiation of previous findings in chopped adrenal cultures, the cardiac glycoside-like activity does not appear to result from cholesterol side-chain cleavage or pregnenolone production, since inhibition of side-chain cleavage as well as subsequent 17 alpha-hydroxylation and 3 beta-dehydrogenation did not result in consistent inhibition of DLI release.  相似文献   
74.
Stem cell carcinoma of the colon and rectum   总被引:2,自引:2,他引:2  
Two cases of highly malignant tumors, one originating in the sigmoid colon and the other in the rectum, are presented. Both tumors showed light microscopic, electron microscopic, and immunohistochemical evidence of multidirectional differentiation. The tumors were composed mainly of undifferentiated cells, but focally merging into areas with adenocarcinomatous and squamous differentiation. Ultrastructurally and histochemically, a predominant endocrine differentiation was present in the undifferentiated areas of the tumors. These two cases lend further support to the recent concept of a pluripotential stem cell in the mucosa of the gastrointestinal tract capable of differentiation in several directions.  相似文献   
75.
Clinical presentation of patients with acute cervical spine injury   总被引:1,自引:0,他引:1  
A retrospective review of 67 patients with acute cervical spine fracture and/or dislocation was conducted at two suburban community hospital emergency departments. The mean age was 39, and two-thirds of the patients were male. Motor vehicle accidents and falls accounted for more than 80% of all injuries. On emergency department evaluation, it was found that there was no history of loss of consciousness in 42 patients (63%), no associated cranio-facial injuries in 31 patients (46%), and a normal sensorimotor examination in 59 patients (88%). Thirty-four patients (50%) were evaluated for cervical range of motion, which was found to be normal in one-third of the cases. The absence of mental status changes, cranio-facial injuries, range of motion abnormalities, and focal neurological findings is, therefore, not uncommon in patients who have sustained cervical spine injury.  相似文献   
76.
77.
Our aim was to characterize the clinical spectrum of anorectal dysfunction among eight patients with progressive systemic sclerosis (PSS) who presented with altered bowel movements with or without fecal incontinence. The anorectum was assessed by physical examination, proctosigmoidoscopy, and anorectal manometry. There was concomitant involvement of the other regions of the digestive tract in all patients as determined by barium studies, endoscopy, or manometry: eight esophageal, three gastric, four small bowel, and two colonic. Seven patients had fecal incontinence, and four also had second-degree complete rectal prolapse. Abnormal anorectal function, particularly abnormal anal sphincter resting pressures, were detected in all patients; anal sphincter pressures were lower in those with rectal prolapse. Rectal capacity and wall compliance were impaired in seven of seven patients. Successful surgical correction of prolapse in three patients resulted in restoration of incontinence for six months and seven years in two of the three patients. We conclude that rectal dysfunction and weakness of the anal sphincters are important factors contributing, respectively, to altered bowel movements and fecal incontinence in patients with gastrointestinal involvement by PSS. Rectal prolapse worsens anal sphincter dysfunction and should be sought routinely as it is a treatable factor aggravating fecal incontinence in patients with PSS.This work was presented in part at the Annual Meeting of the American Gastroenterological Association, May 1992, and appears in abstract form in Gastroenterology 1992;102:A473.Supported in part by the General Clinical Research Center Grant 00585 from the National Institutes of Health.  相似文献   
78.
The aim of this study was to compare the influence of two different instructional climates on the accumulation of moderate-to-vigorous physical activity (MVPA) during a fully-inclusive adapted recreational physical activity program. A total of 32 children (18 typically-developing (TD), and 14 with developmental disabilities (DD) ranging in ages from 5 to 9 years, participated in six, 60-min adapted recreational sessions. Of those six sessions, three incorporated an autonomy-supportive climate (high autonomy), and three incorporated direct instruction (low autonomy). MVPA was measured using accelerometers. A repeated measures ANOVA was conducted to determine significant differences in MVPA between group (TD/DD), climate (autonomy/direct), and a group x climate interaction. Significant group and climate main effects were observed (p?=?0.002 and 0.014, respectively). However, there was not a significant group x climate interaction (p?=?0.313). These results suggest that although the group of children with disabilities spent less time in MVPA compared to their typically-developing peers, all participants spent more time in MVPA for the autonomy-supportive climate compared to the low-autonomous climate. This study is the first to quantitatively assess the efficacy of a fully-inclusive autonomy-supportive climate on physical activity levels in children with and without developmental disabilities.  相似文献   
79.
The national early warning score (NEWS) is recommended to detect deterioration in hospitalised patients. In 2013, a NEWS-based system was introduced in a hospital service with over 250,000 annual admissions, generating large amounts of NEWS data. The quality of such data has not been described. We critically assessed NEWS data recorded over 12 months. This observational study included NEWS records from adult inpatients hospitalized in the Capital Region of Denmark during 2014. Physiological variables and the use of supplementary oxygen (NEWS variables) were recorded. We identified implausible records and assessed the distributions of NEWS variable values. Of 2,835,331 NEWS records, 271,103 (10%) were incomplete with one or more variable missing and 0.2% of records containing implausible values. Digit preferences were identified for respiratory rate, supplementation oxygen flow, pulse rate, and systolic blood pressure. There was an accumulation of pulse rate records below 91 beats per minute. Among complete NEWS records, 64% had NEWS?≥?1; 29% had NEWS?≥?3; and 8% had NEWS?≥?6. In a large set of NEWS data, 10% of the records were incomplete. In a system where data were manually entered into an electronic medical record, digit preferences and the accumulation of pulse rate records below 91 beats per minute, which is the limit for NEWS point generation, showed that staff practice influenced the recorded values. This indicates a potential limitation of transferability of research results obtained in such systems to fully automated systems.  相似文献   
80.
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