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   2676篇
  免费   140篇
  国内免费   22篇
耳鼻咽喉   17篇
儿科学   123篇
妇产科学   46篇
基础医学   273篇
口腔科学   47篇
临床医学   260篇
内科学   452篇
皮肤病学   73篇
神经病学   215篇
特种医学   123篇
外科学   554篇
综合类   122篇
预防医学   139篇
眼科学   42篇
药学   138篇
中国医学   12篇
肿瘤学   202篇
  2024年   3篇
  2023年   16篇
  2022年   27篇
  2021年   74篇
  2020年   52篇
  2019年   65篇
  2018年   63篇
  2017年   43篇
  2016年   38篇
  2015年   60篇
  2014年   53篇
  2013年   101篇
  2012年   143篇
  2011年   161篇
  2010年   92篇
  2009年   90篇
  2008年   130篇
  2007年   162篇
  2006年   149篇
  2005年   152篇
  2004年   137篇
  2003年   127篇
  2002年   104篇
  2001年   110篇
  2000年   82篇
  1999年   81篇
  1998年   40篇
  1997年   35篇
  1996年   30篇
  1995年   26篇
  1994年   18篇
  1993年   11篇
  1992年   57篇
  1991年   45篇
  1990年   38篇
  1989年   45篇
  1988年   27篇
  1987年   24篇
  1986年   27篇
  1985年   19篇
  1984年   16篇
  1983年   8篇
  1982年   6篇
  1981年   4篇
  1980年   9篇
  1979年   11篇
  1978年   8篇
  1977年   4篇
  1976年   3篇
  1973年   3篇
排序方式: 共有2838条查询结果,搜索用时 15 毫秒
91.

Objective

We hypothesize that the amplitude of low-frequency fluctuations (ALFF) is involved in the altered regional baseline brain function in social anxiety disorder (SAD). The aim of the study was to analyze the altered baseline brain activity in drug-naive adult patients with SAD.

Methods

We investigated spontaneous and baseline brain activities by obtaining the resting-state functional magnetic resonance imaging data of 20 drug-naïve adult SAD patients and 19 healthy controls. Voxels were used to analyze the ALFF values using one- and two-sample t-tests. A post-hoc correlation of clinical symptoms was also performed.

Results

Our findings show decreased ALFF in the bilateral insula, left medial superior frontal gyrus, left precuneus, left middle temporal gyrus, right middle temporal pole, and left fusiform gyrus of the SAD group. The SAD patients exhibited significantly increased ALFF in the right inferior temporal gyrus, right middle temporal gyrus, bilateral middle occipital gyrus, orbital superior frontal gyrus, right fusiform gyrus, right medial superior frontal gyrus, and left parahippocampal gyrus. Moreover, the Liebowitz Social Anxiety Scale results for the SAD patients were positively correlated with the mean Z values of the right middle occipital and right inferior occipital but showed a negative correlation with the mean Z values of the right superior temporal gyrus and right medial superior frontal gyrus.

Conclusion

These results of the altered regional baseline brain function in SAD suggest that the regions with abnormal spontaneous activities are involved in the underlying pathophysiology of SAD patients.  相似文献   
92.
TNFalpha is a proinflammatory cytokine that promotes osteoclastic bone resorption. We evaluated the association between a G-308A polymorphism (rs1800629) at the TNFA locus and osteoporosis phenotypes in 4306 older women participating in the Study of Osteoporotic Fractures. Femoral neck bone mineral density (BMD) and structural geometry were measured using dual-energy x-ray absorptiometry and hip structural analysis. Incident fractures were confirmed by physician adjudication of radiology reports. Despite similar femoral neck BMD, women with the A/A genotype had greater subperiosteal width (P = 0.01) and endocortical diameter (P = 0.03) than those with the G/G genotype. The net result of these structural differences was that there was a greater distribution of bone mass away from the neutral axis of the femoral neck in women with the A/A genotype, resulting in greater indices of bone bending strength (cross-sectional moment of inertia: P = 0.004; section modulus: P = 0.003). Among 376 incident hip fractures during 12.1 yr of follow-up, a 22% decrease in the risk of hip fracture was seen per copy of the A allele (relative risk 0.78; 95% confidence interval 0.63, 0.96), which was not influenced by adjustments for potential confounding factors, BMD, or bone strength indices. The G-308A polymorphism was not associated with a reduced risk of other fractures. These results suggest a potential role of genetic variation in TNFalpha in the etiology of osteoporosis.  相似文献   
93.
BACKGROUND/AIMS: Length of stay is an important marker of medical resource consumption. In the modern managed care era physicians are driven to deliver the highest quality of care while using fewest resources. Hepatectomy represents a technically challenging and resource-intensive procedure, particularly in the setting of hepatic malignancy and liver cirrhosis. For improving quality of surgical management in such cases, we aimed to identify the factors affecting length of stay after hepatectomy for patients with hepatocellular carcinoma. METHODOLOGY: A total of 375 consecutive surgical hepatocellular carcinoma patients at a tertiary referral center during a 7-year period were reviewed. Length of stay after hepatectomy longer than 14 days was defined as prolonged length of stay. Patients were divided into two groups according to their length of stay. Patients with length of stay less than or equal to 14 days were in Group A and those with length of stay longer than 14 days were in Group B. Data for comparative analysis between both groups were categorized according to preoperative patients' clinical demographic factors, operation-related factors, and pathological factors. The significant univariate factors were used for subsequent multivariate analysis. RESULTS: The significant independent factors were patients' preoperative prothrombin activity, intraoperative blood transfusion, surgical complication, and the time to abdominal drain removal. Among these independent factors, surgical complication (p < 0.001, relative risk 7.01, and 95% confidence interval 3.46 to 14.18) was the most powerful factor for prolonged length of stay after elective hepatectomy for hepatocellular carcinoma. CONCLUSIONS: Most of the independent factors for prolonged length of stay after elective hepatectomy for hepatocellular carcinoma patients are operation-related and surgeon-dependent. The surgeon plays a key role in determining length of stay. By minimizing blood transfusion, surgical complication, and the time to abdominal drain removal, length of stay can be significantly decreased in hepatocellular carcinoma patients undergoing hepatectomy.  相似文献   
94.
Background: The impact of a low-glucose peritoneal dialysis (PD) regimen on biomarkers of peritoneal inflammation, fibrosis and membrane integrity remains to be investigated.♦ Methods: In a randomized, prospective study, 80 incident PD patients received either a low-glucose regimen comprising Physioneal (P), Extraneal (E) and Nutrineal (N) (Baxter Healthcare Corporation, Deerfield, IL, USA) (PEN group), or Dianeal (control group) for 12 months, after which both groups continued with Dianeal dialysis for 6 months. Serum and dialysate levels of vascular endothelial growth factor (VEGF), decorin, hepatocyte growth factor (HGF), interleukin-6 (IL-6), macrophage migration inhibitory factor (MIF), hyaluronan (HA), adiponectin, soluble-intracellular adhesion molecule (s-ICAM), vascular cell adhesion molecule-1 (VCAM-1) and P-selectin, and dialysate cancer antigen 125 (CA125), were measured after 12 and 18 months. This paper focuses on results after 12 months, when patients in the PEN group changed to glucose-based PD fluid (PDF).♦ Results: At the end of 12 months, effluent dialysate levels of CA125, decorin, HGF, IL-6, adiponectin and adhesion molecules were significantly higher in the PEN group compared to controls, but all decreased after patients switched to glucose-based PDF. Macrophage migration inhibitory factor level was lower in the PEN group but increased after changing to glucose-based PDF and was similar to controls at 18 months. Serum adiponectin level was higher in the PEN group at 12 months, but was similar in the 2 groups at 18 months. Body weight, residual renal function, ultrafiltration volume and total Kt/V did not differ between both groups. Dialysate-to-plasma creatinine ratio at 4 h was higher in the PEN group at 12 months and remained so after switching to glucose-based PDF.♦ Conclusion: Changes in the biomarkers suggest that the PEN PD regimen may be associated with better preservation of peritoneal membrane integrity and reduced systemic vascular endothelial injury.  相似文献   
95.
96.
Purpose: To evaluate the performance of a prehospital trauma diversion system in Hong Kong, China. Methods: A retrospective analysis of prospectively collected data in the trauma registry of Queen Mary Hospital, Hong Kong from 1 January 2009 to 31 December 2013 was done. All adult patients aged 18 years or above, either primarily or secondarily diverted to Queen Mary Hospital according to the trauma patient diversion protocol, were recruited. Need for trauma center level of care was based on a consensus-based criterion standard published in 2014. Performance of the protocol in terms of overdiversion and under-diversion was determined. Results: A total of 209 patients were included for analysis. About 30% of the patients required trauma center level of care. The most common reason was the need for vascular, neurologic, abdominal, thoracic, pelvic, spine or limb-conserving surgery within 24 h of presentation. The over-diversion rate and underdiversion rate were 69.6% and 19.7% respectively. Conclusion: The trauma patient diversion protocol currently in use in Hong Kong is not accurate enough. Further revision and refinement is needed.  相似文献   
97.
98.
99.
Height is a highly heritable and classic polygenic trait. Recent genome-wide association studies (GWAS) have revealed that at least 180 genetic variants influence adult height. However, these variants explain only about 10% of the phenotypic variation in height. Genetic analysis of short individuals can lead to the discovery of novel rare gene defects with a large effect on growth. In an effort to identify novel genes associated with short stature, genome-wide analysis for copy number variants (CNVs), using single-nucleotide polymorphism arrays, in 162 patients (149 families) with short stature was performed. Segregation analysis was performed if possible, and genes in CNVs were compared with information from GWAS, gene expression in rodents'' growth plates and published information. CNVs were detected in 40 families. In six families, a known cause of short stature was found (SHOX deletion or duplication, IGF1R deletion), in two combined with a de novo potentially pathogenic CNV. Thirty-three families had one or more potentially pathogenic CNVs (n=40). In 24 of these families, segregation analysis could be performed, identifying three de novo CNVs and nine CNVs segregating with short stature. Four were located near loci associated with height in GWAS (ADAMTS17, TULP4, PRKG2/BMP3 and PAPPA). Besides six CNVs known to be causative for short stature, 40 CNVs with possible pathogenicity were identified. Segregation studies and bioinformatics analysis suggested various potential candidate genes.  相似文献   
100.
Double-chambered right ventricle (DCRV) is a rare form of right ventricular outflow tract (RVOT) obstruction accounting for approximately 1% of patients with congenital heart disease. It consists of an anomalous muscle bundle that divides the right ventricle usually between the sinus (inlet) and the infundibulum (outlet). This division creates a proximal chamber with high pressure and a distal chamber with low pressure. The hemodynamic obstruction of the RVOT is usually an acquired phenomenon, however the substrate for the anomalous muscle bundle is likely congenital. The diagnosis of DCRV should be considered in the young patient with an elevated right ventricular systolic pressure and intracavitary gradient. Echocardiography and cardiac MRI are the principal diagnostic tools for the assessment of DCRV. This entity is often misdiagnosed as pulmonary hypertension in the young patient, and can often go overlooked and untreated for many years. Definitive therapy involves surgical resection of the muscle bundle. This can often be curative and if done in a timely fashion, may prevent right ventricular remodeling. We describe the unique diagnostic dilemma, the course and management of a young adult with DCRV during pregnancy.  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