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   2388篇
  免费   188篇
  国内免费   14篇
耳鼻咽喉   17篇
儿科学   65篇
妇产科学   33篇
基础医学   438篇
口腔科学   55篇
临床医学   222篇
内科学   466篇
皮肤病学   147篇
神经病学   332篇
特种医学   103篇
外科学   237篇
综合类   5篇
一般理论   2篇
预防医学   141篇
眼科学   45篇
药学   101篇
中国医学   2篇
肿瘤学   179篇
  2023年   51篇
  2022年   65篇
  2021年   129篇
  2020年   79篇
  2019年   97篇
  2018年   105篇
  2017年   75篇
  2016年   94篇
  2015年   110篇
  2014年   114篇
  2013年   143篇
  2012年   184篇
  2011年   181篇
  2010年   96篇
  2009年   90篇
  2008年   102篇
  2007年   104篇
  2006年   114篇
  2005年   102篇
  2004年   93篇
  2003年   61篇
  2002年   75篇
  2001年   26篇
  2000年   30篇
  1999年   24篇
  1998年   20篇
  1997年   7篇
  1996年   15篇
  1995年   9篇
  1994年   7篇
  1993年   5篇
  1992年   16篇
  1991年   11篇
  1990年   10篇
  1989年   10篇
  1988年   8篇
  1986年   5篇
  1985年   5篇
  1984年   16篇
  1983年   7篇
  1982年   4篇
  1981年   4篇
  1980年   5篇
  1979年   14篇
  1978年   9篇
  1977年   5篇
  1974年   4篇
  1973年   7篇
  1972年   4篇
  1961年   4篇
排序方式: 共有2590条查询结果,搜索用时 765 毫秒
11.
BACKGROUND: Knowledge about the long-term course of allergy or sensitization to natural rubber latex (NRL) is insufficient. OBJECTIVE: To investigate the long-term effect of preventive measures on sensitization variables in health care workers who had been diagnosed as having NRL allergy (NRLA) or NRL sensitization (NRLS) without clinical symptoms. METHODS: Repeated follow-up investigations, skin prick tests, and NRL specific IgE serum antibodies were performed in 88 health care workers-33 with NRLA and 55 with NRLS. All workers had been instructed to avoid NRL exposure. At the workplace, powder-free NRL gloves for all other employees were gradually introduced. Re-evaluations were done at 14 +/- 3.7 (N = 86) and 38 +/- 4.0 (N = 78) months after the first examination. RESULTS: At the last follow-up, a loss of skin prick test reactivity to NRL was observed in 1 of 29 subjects with NRLA (3.4%) and 16 of 35 with NRLS (45.7%) with previous skin test reactions (P < .001). Among those subjects who demonstrated a kU/L level (CAP class) equal to or greater than class I to NRL at the initial examination, NRL-specific IgE was absent at the last follow-up in 8 (32.0%) of 25 subjects with NRLA and 14 (38.9%) of 36 with NRLS. At the final examination, we could no longer demonstrate sensitization to NRL by any method in 24 (27.3%) of 88 health care workers. Complete loss of NRL sensitization was less frequent in subjects with NRLA than in those with NRLS (1 of 33 or 3.0% vs 23 of 55 or 41.8%; P < .001). CONCLUSIONS: Implementation of simple preventive measures lowers markers of sensitization to NRL quickly in many health care workers with NRLA or NRLS.  相似文献   
12.
Platyspondylic lethal skeletal dysplasia (PLSD) Torrance type (PLSD-T) is a rare skeletal dysplasia characterized by platyspondyly, brachydactyly, and metaphyseal changes. Generally a perinatally lethal disease, a few long-term survivors have been reported. Recently, mutations in the carboxy-propeptide of type II collagen have been identified in two patients with PLSD-T, indicating that PLSD-T is a type 2 collagen-associated disorder. We studied eight additional cases of PLSD-T and found that all had mutations in the C-propeptide domain of COL2A1. The mutational spectrum includes missense, stop codon and frameshift mutations. All non-sense mutations were located in the last exon, where they would escape non-sense-mediated RNA-decay. We conclude that PLSD-T is caused by mutations in the C-propeptide domain of COL2A1, which lead to biosynthesis of an altered collagen chain (as opposed to a null allele). Similar mutations have recently been found to be the cause of spondyloperipheral dysplasia, a non-lethal dominant disorder whose clinical and radiographical features overlap those of the rare long-term survivors with PLSD-T. Thus, spondyloperipheral dysplasia and PLSD-T constitute a novel subfamily within the type II collagenopathies, associated with specific mutations in the C-propeptide domain and characterized by distinctive radiological features including metaphyseal changes and brachydactyly that set them apart from other type 2 collagenopathies associated with mutations in the triple-helical domain of COL2A1. The specific phenotype of C-propeptide mutations could result from a combination of diminished collagen fibril formation, toxic effects through the accumulation of unfolded collagen chains inside the chondrocytes, and alteration of a putative signaling function of the carboxy-propeptide of type 2 collagen.  相似文献   
13.
The pitch identification performance of absolute pitch possessors has previously been shown to depend on pitch range, key color, and timbre of presented tones. In the present study, the dependence of pitch identification performance on key color and timbre of musical tones was examined by analyzing hit rates, reaction times, and pupillary responses of absolute pitch possessors (n = 9) and nonpossessors (n = 12) during a pitch identification task. Results revealed a significant dependence of pitch identification hit rate but not reaction time on timbre and key color in both groups. Among absolute pitch possessors, peak dilation of the pupil was significantly dependent on key color whereas the effect of timbre was marginally significant. Peak dilation of the pupil differed significantly between absolute pitch possessors and nonpossessors. The observed effects point to the importance of learning factors in the acquisition of absolute pitch.  相似文献   
14.
Using human-mouse somatic cell hybrids containing different parts of chromosome 6 and a DNA probe of the oncogene (V-myb) of avian myeloblastosis virus (AMV), we regionally mapped by Southern blot techniques the human cellular myb (cmyb) protooncogene to 6q21qter.  相似文献   
15.
Quality of Life Research - The objective of this study was to determine the influence of postanesthesia care unit (PACU)&nbsp;delirium on self-reported cognitive function and perceived health...  相似文献   
16.
Journal of Public Health - Offshore wind energy is a fast growing market. Accordingly, a correspondingly large number of employees are working at the wind farms. Owing to the harsh operating...  相似文献   
17.
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - SARS-CoV-2-Antikörperstudien ergänzen und erweitern die Erkenntnisse aus der Meldestatistik laborbestätigter...  相似文献   
18.
BackgroundIt is unknown, whether metastatic prostate cancer (CaP) patients with intermediate life expectancy (5–10 years) should be considered for external beam radiation therapy (EBRT) to the prostate. We addressed this void.MethodsWithin the Surveillance, Epidemiology, and End Results database (2004–2016), we identified 835 M1a or M1b CaP substaged patients with prostate-specific antigen (PSA) < 20 ng/ml and with intermediate life expectancy (LE) 5 to 10 years, treated with EBRT or no EBRT. Inverse probability of treatment-weighting (IPTW), Kaplan-Meier plots and Cox-regression models (CRMs) were used.ResultsOverall, 179 (21.4%) patients received EBRT and 656 (78.6%) did not. EBRT rates increased from 13.9 to 23.8% (2004–2016; P= 0.04). After IPTW-adjustment, median OS was 45 vs. 35 months, in EBRT vs. no EBRT patients (P < 0.001). In IPTW-adjusted Cox-regression models, EBRT independently predicted lower overall mortality (hazard ratio [HR]: 0.7, CI 0.61–0.89; P= 0.001). After stratification according to M1 substages, EBRT was associated with lower overall mortality in M1a (HR: 0.2, CI 0.05–0.91; P= 0.03) and M1b (HR: 0.7, CI 0.55–0.88; P = 0.003) substages.ConclusionEBRT was associated with lower mortality in metastatic CaP patients with low PSA and intermediate LE (5–10 years). In consequence, greater consideration for EBRT should be given in those patients. However, it is important to consider study limitations until clinical trials confirm the proposed benefit.  相似文献   
19.
BackgroundThe NCCN guidelines recommend active surveillance (AS) as an option for the initial management of cT1a 0-2 cm renal lesions. However, data about comparison between renal cell carcinoma (RCC) 0-2 cm vs. 2.1-4 cm are scarce.MethodsWithin the Surveillance, Epidemiology, and End Results database (2002–2016), 46,630 T1a NanyMany stage patients treated with nephrectomy were identified. Data were tabulated according to histological subtype, tumor grade (low [LG] vs. high [HG]), as well as age category and gender. Additionally, rates of synchronous metastases were quantified.ResultsOverall, 69.3 vs. 74.1% clear cell, 21.4 vs. 17.6% papillary, 6.9 vs. 6.8% chromophobe, 2.0 vs. 1.1% sarcomatoid dedifferentiation, 0.2 vs. 0.2% collecting duct histological subtype were identified for respectively 0-2 cm and 2.1-4 cm RCCs. In both groups, advanced age was associated with higher rate of HG clear cell and HG papillary histological subtype. In 0-2 cm vs. 2.1-4 cm RCCs, 13.8% vs. 20.2% individuals operated on harbored HG tumors and were more prevalent in males. Lower synchronous metastases rates were recorded in 0-2 cm RCC and ranged from 0 in respectively multilocular cystic to 0.9% in HG papillary histological subtype. The highest synchronous metastases rates were recorded in sarcomatoid dedifferentiation histological subtype (13.8% and 9.7%) in both groups.ConclusionsRelative to 2.1-4 cm RCCs, 0-2 cm RCCs harbored lower rates of HG tumors, lower rates of aggressive variant histology and lower rates of synchronous metastases. The indications and demographics of patients selected for AS may be expanded in the future to include younger and healthier patients.  相似文献   
20.
Primary and recurrent cytomegalovirus (CMV) infections frequently cause CMV colitis in immunocompromised as well as inflammatory bowel disease (IBD) patients. Additionally, colitis occasionally occurs upon primary CMV infection in patients who are apparently immunocompetent. In both cases, the underlying pathophysiologic mechanisms are largely elusive - in part due to the lack of adequate access to specimens. We employed the mouse cytomegalovirus (MCMV) model to assess the association between CMV and colitis. During acute primary MCMV infection of immunocompetent mice, the gut microbial composition was affected as manifested by an altered ratio of the Firmicutes to Bacteroidetes phyla. Interestingly, these microbial changes coincided with high-titer MCMV replication in the colon, crypt hyperplasia, increased colonic pro-inflammatory cytokine levels, and a transient increase in the expression of the antimicrobial protein Regenerating islet-derived protein 3 gamma (Reg3γ). Further analyses revealed that murine and human intestinal epithelial cell lines, as well as primary intestinal crypt cells and organoids represent direct targets of CMV infection causing increased cell death. Accordingly, in vivo MCMV infection disrupted the intestinal epithelial barrier and increased apoptosis of intestinal epithelial cells. In summary, our data show that CMV transiently induces colitis in immunocompetent hosts by altering the intestinal homeostasis.  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