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   36245篇
  免费   2565篇
  国内免费   431篇
耳鼻咽喉   704篇
儿科学   420篇
妇产科学   512篇
基础医学   5948篇
口腔科学   939篇
临床医学   3152篇
内科学   7080篇
皮肤病学   1276篇
神经病学   2701篇
特种医学   2286篇
外科学   4699篇
综合类   164篇
现状与发展   3篇
一般理论   10篇
预防医学   1303篇
眼科学   692篇
药学   3618篇
中国医学   571篇
肿瘤学   3163篇
  2023年   183篇
  2022年   644篇
  2021年   1360篇
  2020年   731篇
  2019年   1055篇
  2018年   1203篇
  2017年   994篇
  2016年   1472篇
  2015年   1954篇
  2014年   2129篇
  2013年   2469篇
  2012年   3620篇
  2011年   3362篇
  2010年   2078篇
  2009年   1616篇
  2008年   2199篇
  2007年   1941篇
  2006年   1670篇
  2005年   1615篇
  2004年   1270篇
  2003年   1132篇
  2002年   928篇
  2001年   446篇
  2000年   428篇
  1999年   352篇
  1998年   179篇
  1997年   151篇
  1996年   102篇
  1995年   85篇
  1994年   79篇
  1993年   84篇
  1992年   123篇
  1991年   139篇
  1990年   118篇
  1989年   104篇
  1988年   95篇
  1987年   83篇
  1986年   84篇
  1985年   68篇
  1984年   45篇
  1983年   42篇
  1982年   33篇
  1980年   31篇
  1979年   56篇
  1978年   41篇
  1975年   52篇
  1972年   39篇
  1971年   50篇
  1970年   34篇
  1968年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Alkaline conditions in the oral cavity may be caused by a variety of stimuli, including tobacco products, antacids, alkaline drinking water and bicarbonate toothpaste. However, the effects of an alkaline pH on the oral mucosa had not been elucidated. The purpose of this study was to investigate how basal keratinocytes are actively involved in re-epithelialization after alkaline chemical injury. We generated epithelial defects in the oral mucosa of mice by applying an alkaline chemical, and the localization of cytokeratin 13, cytokeratin 14, PCNA and p63 was investigated during the re-epithelialization process. PCNA- and p63-positive staining was seen in basal cells covering the wound surface at 1 day after the chemical injury. Cytokeratin 14-positive and PCNA-negative basal keratinocytes were localized in a few layers of the wound epithelium during epithelial outgrowth. Cytokeratin 14-positive and PCNA-positive basal keratinocytes, indicating proliferation, were localized over the entire layer of the epithelium at the wound margin. These results imply that basal keratinocytes at the wound margin migrate to the wound surface, provoke differentiation and keratinization during epithelial outgrowth and that epithelial cells are supplied from the wound margin to the epithelial outgrowth after alkaline chemical injury.  相似文献   
992.
We present a carbon nanotube-field effect transistor (CNT-FET) biosensor which first implements the chemodosimeter sensing principle in CNT nanoelectronics. We experimentally illustrate the specific molecular interplay that the cysteine-selective chemodosimeter immobilized on the CNT surface can specifically interact with cysteine, which leads to the chemical transformation of the chemodosimeter. Since the chemical transformation of the chemodosimeter can disrupt the charge distribution in the vicinity of the CNT surface, the carrier equilibrium in CNT might be altered, and manifested by the conductivity change of CNT-FET. The real-time conductance measurements show our biosensor is capable of label-free, rapid, highly selective and ultrasensitive detection of cysteine with a detection limit down to 0.45 fM. These results first verify the signaling principle competency of chemical transformation of the chemodosimeter in CNT electronic sensors. Combined with the advantages of the highly selective chemodosimeter and sensitive CNT-FET, the excellent performance of our sensor indicates its promising prospect as a valuable tool for developing highly sensitive and selective sensing platforms in practical application.

The utility of the chemodosimetric sensing principle was demonstrated for the first time in electronic biosensing with CNT-FET devices.  相似文献   
993.
The aim of this study was to determine whether skin temperature measurement by digital thermography on hands and feet is useful for diagnosis of Raynaud''s phenomenon (RP). Fifty-seven patients with RP (primary RP, n = 33; secondary RP, n = 24) and 146 healthy volunteers were recruited. After acclimation to room temperature for 30 min, thermal imaging of palmar aspect of hands and dorsal aspect of feet were taken. Temperature differences between palm (center) and the coolest finger and temperature differences between foot dorsum (center) and first toe significantly differed between patients and controls. The area under curve analysis showed that temperature difference of the coolest finger (cutoff value: 2.2℃) differentiated RP patients from controls (sensitivity/specificity: 67/60%, respectively). Temperature differences of first toe (cutoff value: 3.11℃) also discriminated RP patients (sensitivity/specificity: about 73/66%, respectively). A combination of thermographic assessment of the coolest finger and first toe was highly effective in men (sensitivity/specificity : about 88/60%, respectively) while thermographic assessment of first toe was solely sufficient for women (sensitivity/specificity: about 74/68%, respectively). Thermographic assessment of the coolest finger and first toe is useful for diagnosing RP. In women, thermography of first toe is highly recommended.

Graphical Abstract

相似文献   
994.
Transient elastography (TE) has been used as a non-invasive method for liver stiffness measurement (LSM) in patients with chronic liver disease. This study was performed to assess the change of LSM by TE and to assess its clinical usefulness during long-term oral antiviral therapy in patients with chronic hepatitis B (CHB). We retrospectively reviewed 83 CHB patients. The mean interval between two LSM was 411.5 ± 149.5 days. Initial and follow-up LSM was 16.15 ± 12.41 kPa and 11.26 ± 7.36 kPa, respectively (P < 0.001). The degree of regression of liver stiffness was -2.03 ± 0.36% per month. The fibrosis stage classified by LSM value improved in 37 (44.6%) patients during oral antiviral therapy. Of the 30 (36.1%) patients with LSM ≥ 14.1 kPa (cirrhosis) at 1st LSM, 12 (40%) proved to no longer have cirrhosis (≥ 1 decrease in fibrosis stage) at 2nd LSM. LSM significantly decreased in both baseline high (> upper limit of normal [ULN] × 2) and low (≤ ULN × 2) alanine aminotransferase groups during antiviral therapy (P < 0.001; P = 0.001, respectively). Long-term oral antiviral therapy resulted in the improvement of liver stiffness in a substantial portion of patients with CHB. TE may be used a useful clinical tool to assess disease progression in CHB patients.

Graphical Abstract

相似文献   
995.
Owing to the rarity of the disease, epidemiologic information on achalasia is limited. This study aimed to investigate the epidemiology and treatment patterns of achalasia in the population of Korea using a national healthcare database. The diagnostic code K22.0 of the International Classification of Diseases was used to identify cases of achalasia between 2007 and 2011. Treatment modalities for achalasia were identified using the electronic data interchange codes Q7642 or Q7641 for balloon dilation and QA421 or QA422 for esophago-cardiomyotomy. A total of 3,105 patients with achalasia (1,447 men; mean age, 52.5 yr) were identified between 2007 and 2011, indicating a prevalence of 6.29/100,000 (95% confidence interval [CI], 4.94-7.66) during this 5-yr period. A total of 191 incident cases of achalasia (82 men; mean age, 49.5 yr), which were not diagnosed as achalasia in the previous 4 yr, were detected in 2011, indicating an incidence of 0.39/100,000 (95% CI, 0.15-0.63) for that year. During the study period, balloon dilation therapy was performed a total of 975 times in 719 patients, and surgical esophago-cardiomyotomy was performed once per patient in 17 patients. This is the first population-based epidemiologic study of achalasia in Korea.

Graphical Abstract

相似文献   
996.
Congenital pulmonary lymphangiectasia (CPL) is a rare lymphatic pulmonary abnormality. CPL with respiratory distress has a poor prognosis, and is frequently fatal in neonates. We report a case of pneumonectomy for CPL in a newborn. An infant girl, born at 39 weeks'' after an uncomplicated pregnancy, exhibited respiratory distress 1 hr after birth, which necessitated intubation and aggressive ventilator care. Right pneumonectomy was performed after her symptoms worsened. Histologic examination indicated CPL. She is currently 12 months old and developing normally. Pneumonectomy can be considered for treating respiratory symptoms for improving chances of survival in cases with unilateral CPL.

Graphical Abstract

相似文献   
997.
The object of this study was to evaluate the effect of uric acid lowering therapy in reducing the new development of comorbidities and the frequency of acute attacks in gout patients. We retrospectively reviewed patients who were diagnosed to have gout with at least 3 yr of follow up. They were divided into 2 groups; 53 patients with mean serum uric acid level (sUA)<6 mg/dL and 147 patients with mean sUA≥6 mg/dL. Comorbidities of gout such as hypertension (HTN), type II diabetes mellitus (DM), chronic kidney disease, cardiovascular disease (CVD) and urolithiasis were compared in each group at baseline and at last follow-up visit. Frequency of acute gout attacks were also compared between the groups. During the mean follow up period of 7.6 yr, the yearly rate of acute attack and the new development of HTN, DM, CVD and urolithiasis was lower in the adequately treated group compared to the inadequately treated group. Tight control of uric acid decreases the incidence of acute gout attacks and comorbidities of gout such as HTN, DM, CVD and urolithiasis.

Graphical Abstract

相似文献   
998.
Pituitary adenoma (PA) is a common benign neuroendocrine tumor; however, the incidence and proportion of hormone-producing PAs in Korean patients remain unknown. Authors analyzed 506 surgically resected and pathologically proven pituitary lesions of the Seoul National University Hospital from 2006 to 2011. The lesions were categorized as: PAs (n = 422, 83.4%), Rathke''s cleft cysts (RCCs) (n = 54, 10.6%), inflammatory lesions (n = 8, 1.6%), meningiomas (n = 4), craniopharyngiomas (n = 4), granular cell tumors (n = 1), metastatic renal cell carcinomas (n = 2), germinomas (n = 1), ependymomas (n = 1), and unsatisfactory specimens (n = 9, 1.8%). PAs were slightly more prevalent in women (M: F = 1:1.17) with a mean age of 48.8 yr (9-80 yr). Immunohistochemical analysis revealed that prolactin-producing PAs (16.6%) and growth hormone-producing adenomas (9.2%) were the most common functional PAs. Plurihormonal PAs and nonfunctioning (null cell) adenomas were found in 14.9% and 42.4% of patients with PAs, respectively. The recurrence rate of PAs was 11.1%, but nearly 0% for the remaining benign lesions such as RCCs. 25.4% of patients with PAs were treated by gamma-knife after surgery due to residual tumors or regrowth of residual tumor. In conclusion, the pituitary lesions and the proportions of hormone-producing PAs in Korean patients are similar to those of previous reports except nonfunctioning (null cell) PAs, which are unusually frequent.

Graphical Abstract

相似文献   
999.
This study assessed the prevalence of, and risk factors for, iron deficiency (ID) and iron deficiency anemia (IDA) among participants of the fifth Korean Health and Nutrition Examination Survey, 2010. Of 8,958 participants, 6,758 individuals ≥10 yr had sufficient data for the analysis of anemia and iron status. ID was defined as a transferrin saturation <10% or serum ferritin <15 µg/L. The prevalence of ID and IDA was 2.0% (95% confidence interval [CI], 1.3%-2.6%) and 0.7% (95% CI, 0.3%-1.0%), respectively, in males, and 22.4% (95% CI, 20.7%-24.2%) and 8.0% (95% CI, 6.8%-9.2%), respectively, in females. In reproductive age females, the prevalence of ID and IDA was 31.4% (95% CI, 28.9%-33.8%) and 11.5% (95% CI, 9.6%-13.4%), respectively. Compared to the prevalence of IDA in adult males 18-49 yr, the relative risks of IDA in adults ≥65 yr, lactating females, premenopausal females, and pregnant females were 8.1, 35.7, 42.8, and 95.5, respectively. Low income, underweight, iron- or vitamin C-poor diets were also associated with IDA. For populations with defined risk factors in terms of age, gender, physiological state and socioeconomic and nutritional status, national health policy to reduce IDA is needed.

Graphical Abstract

相似文献   
1000.
The rapid response system (RRS) is an innovative system designed for in-hospital, at-risk patients but underutilization of the RRS generally results in unexpected cardiopulmonary arrests. We implemented an extended RRS (E-RRS) that was triggered by actively screening at-risk patients prior to calls from primary medical attendants. These patients were identified from laboratory data, emergency consults, and step-down units. A four-member rapid response team was assembled that included an ICU staff, and the team visited the patients more than twice per day for evaluation, triage, and treatment of the patients with evidence of acute physiological decline. The goal was to provide this treatment before the team received a call from the patient''s primary physician. We sought to describe the effectiveness of the E-RRS at preventing sudden and unexpected arrests and in-hospital mortality. Over the 1-yr intervention period, 2,722 patients were screened by the E-RRS program from 28,661 admissions. There were a total of 1,996 E-RRS activations of simple consultations for invasive procedures. After E-RRS implementation, the mean hospital code rate decreased by 31.1% and the mean in-hospital mortality rate was reduced by 15.3%. In conclusion, the implementation of E-RRS is associated with a reduction in the in-hospital code and mortality rates.

Graphical Abstract

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