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   7968篇
  免费   397篇
  国内免费   76篇
耳鼻咽喉   102篇
儿科学   179篇
妇产科学   31篇
基础医学   848篇
口腔科学   203篇
临床医学   524篇
内科学   2123篇
皮肤病学   177篇
神经病学   634篇
特种医学   309篇
外科学   1253篇
综合类   37篇
预防医学   183篇
眼科学   268篇
药学   663篇
中国医学   9篇
肿瘤学   898篇
  2023年   53篇
  2022年   129篇
  2021年   207篇
  2020年   131篇
  2019年   160篇
  2018年   223篇
  2017年   166篇
  2016年   207篇
  2015年   216篇
  2014年   261篇
  2013年   327篇
  2012年   550篇
  2011年   572篇
  2010年   350篇
  2009年   269篇
  2008年   513篇
  2007年   532篇
  2006年   520篇
  2005年   494篇
  2004年   443篇
  2003年   415篇
  2002年   422篇
  2001年   103篇
  2000年   96篇
  1999年   110篇
  1998年   96篇
  1997年   75篇
  1996年   69篇
  1995年   58篇
  1994年   51篇
  1993年   44篇
  1992年   70篇
  1991年   52篇
  1990年   41篇
  1989年   56篇
  1988年   42篇
  1987年   37篇
  1986年   31篇
  1985年   39篇
  1984年   33篇
  1983年   15篇
  1982年   19篇
  1981年   22篇
  1980年   16篇
  1979年   13篇
  1978年   10篇
  1977年   8篇
  1975年   9篇
  1974年   13篇
  1971年   8篇
排序方式: 共有8441条查询结果,搜索用时 15 毫秒
81.
Nine hundred eight women aged 40-88 years living in a non-Cd-polluted area in Japan were analyzed for urinary cadmium (Cd), N-acetyl-beta-D-glucosaminidase (NAG) activity, beta(2)-microglobulin (B2MG) concentration, and for the stiffness index (STIFF) of calcaneal bone using an ultrasound method. The urinary Cd in the subjects, with a mean and range of 2.87 and 0.25-11.4 microg/g creatinine, respectively, showed a significant correlation with NAG but not with B2MG. STIFF was significantly inversely correlated with urinary Cd, and the association remained significant after adjusting for age, body weight, and menstrual status, suggesting a significant effect of Cd on the bone loss in these subjects without signs of Cd-induced kidney damage. A two-fold increase in urinary Cd was accompanied by a decrease in STIFF corresponding to a 1.7-year rise in age. These results emphasize the need for reassessment of the significance of Cd exposure in the general Japanese population.  相似文献   
82.
BackgroundThe transtheoretical model (TTM) is composed of the multiple stages according to patient’s consciousness and is believed to lead people to realize the importance of healthier behaviors. We examined the association of TTM stages with the decline of estimated glomerular filtration rate (eGFR).MethodsWe used the annual health checkup data and health insurance claims data of the Japan Health Insurance Association in Kyoto Prefecture between April 2012 and March 2016. TTM stages of change obtained from questionnaires at the first health checkup and categorized into six groups. The primary outcome was defined as a more than 30% decline in eGFR from the first health checkup. We fitted multivariable Cox proportional-hazards model for time-to-event analyses adjusting for age, sex, eGFR, body mass index, blood pressure, blood sugar, dyslipidemia, uric acid, urinary protein, and existence of kidney diseases at first health checkup.ResultsWe analyzed 239,755 employees and the mean follow-up was 2.9 (standard deviation, 1.2) years. As compared with the stage 1 group, the risk of eGFR decline was significantly low in the stage 3 group (hazard ratio [HR] 0.77; 95% confidence interval [CI], 0.65–0.91); stage 4 group (HR 0.80; 95% CI, 0.65–0.98); and stage 5 group (HR 0.79; 95% CI, 0.66–0.95).ConclusionCompared with the precontemplation stage (stage 1), the preparation, action and maintenance stages (stages 3, 4, and 5), were associated with a lower risk of eGFR decline.Key words: transtheoretical model, chronic kidney disease, kidney injury, stage of change, more than 30% decline in estimated glomerular filtration rate  相似文献   
83.
A 43-year-old male with a history of autosomal dominant polycystic kidney disease (ADPKD) was admitted to our center with severe abdominal pain and was diagnosed with acute pancreatitis. CT showed multiple cysts in the liver and both kidneys along with ADPKD and a cystic mass, 4 cm in diameter, in the pancreatic head. The main pancreatic duct was dilated to 1 cm in diameter. The patient was diagnosed with acute pancreatitis due to intraductal papillary mucinous tumor (IPMT), and pancreatoduodenectomy was performed. Histologic examination revealed a multiloculated cystic tumor filled with mucin in the head of the pancreas. Microscopically, the tumor was diagnosed as adenocarcinoma and was found to have invaded the main pancreatic duct. Although, in addition to our case, only seven cases with association between ADPKD and malignant neoplasms have been reported, five of these cases had neoplasms arising from the pancreas. Therefore, we suggest that some genetic interactions may exist between ADPKD and pancreatic carcinogenesis.  相似文献   
84.

Background

In recent years, surgical outcomes have improved, and positive reports on surgery for type A aortic dissection (AAD) in the elderly are increasing. However, the difference between surgical and conservative treatments in the elderly remains unclear. Therefore, we conducted this study to determine whether surgery should be performed for Stanford (AAD) in elderly patients.

Methods

Data of patients aged 80?years or older who were hospitalized for AAD from April 2014 to March 2016 were extracted from the Japanese national inpatient database. Outcome measures were all-cause in-hospital death, stroke, acute kidney injury and tracheotomy, and composite adverse events (consisting of all-cause in-hospital death, stroke, acute kidney injury, and tracheotomy), and we compared them between surgical and conservative treatments using propensity score matching.

Results

The study cohort included 3258 patients, with 845 matched pairs (1690 patients) in the propensity score matching. All-cause in-hospital death was significantly lower in the surgical treatment group than in the conservative treatment group before and after matching (15.6% vs. 51.1%, p?<?0.001; 16.7% vs. 31.6%, p?<?0.001, respectively); however, there was no significant difference in composite adverse events after matching (36.0%, conservative vs. 37.2%, surgical; p?=?0.65), and adjusted odds ratio was 1.06 and 95% confidence interval was 0.86–1.29 (p?=?0.61) with reference to conservative treatment.

Conclusions

All-cause in-hospital death among elderly patients with AAD was significantly lower in patients treated surgically than in those undergoing conservative treatment. However, there was no significant difference between the two groups in the event-free survival, which is important for the elderly. These findings may be used in the consideration of treatment course for elderly patients with AAD.
  相似文献   
85.
Background Although extrahepatic metastasis occurs rarely after hepatic resection for hepatocellular carcinoma (HCC), the prognosis of these patients is extremely poor. Predictors of extrahepatic metastasis have not been fully investigated. Methods To identify predictors of extrahepatic metastasis after resection, we retrospectively investigated 77 patients with HCC tumors >50 mm in diameter who underwent hepatic resection. We investigated correlations between postoperative extrahepatic metastasis and clinicopathologic factors as well as extrahepatic metastasis-free survival rate by log rank test and predictors of extrahepatic metastasis by univariate and multivariate logistic regression models. Results Hepatitis B surface antigen (HBs-Ag) was found in 25 (32.5%) of 77 patients, and extrahepatic metastasis occurred in 26 (33.8%). Patients with extrahepatic metastasis showed better liver function and a high occurrence of HBs-Ag positivity than those without. The 5-year extrahepatic metastasis-free survival rate was worse in patients with HBs-Ag positivity, larger tumors (≥70 mm), higher alfa-fetoprotein level (≥300 ng/mL), and lower indocyanine green retention rate at 15 minutes (ICGR15) (<15%) than in those without. By univariate logistic regression analysis, HBs-Ag positivity, larger HCC tumor (≥70 mm), lower ICGR15 (<15%), and lower preoperative lymphocyte count (<1000/mm3) were predictors of extrahepatic metastasis (P < .1). By multivariate analysis, HBs-Ag positivity was an independent predictor of postoperative extrahepatic metastasis (P = .04). Conclusions In patients positive for HBs-Ag, radiologic examination of extrahepatic organs should be performed as a part of the postoperative surveillance. Hepatitis B virus infection may promote establishment of extrahepatic metastasis.  相似文献   
86.
87.
88.
Short-term bronchodilator responsiveness to an inhaled β 2 adrenergic agonist was assessed by changes in forced expiratory volume in 1 second (FEV1) in nonsmoking adults with controlled asthma (mild disease, 20 patients; moderate disease, 20 patients; severe disease, 18 patients). Responsiveness correlated significantly with age and with percent of predicted FEV1 (%FEV1) except in patients with severe asthma, who showed significantly less responsiveness than others. Thus, responsiveness is closely associated with degree of airflow limitation in patients with controlled asthma and is significantly influenced by severity of disease and by aging.  相似文献   
89.
Angiopoietin-1 promotes LYVE-1-positive lymphatic vessel formation   总被引:20,自引:3,他引:20       下载免费PDF全文
Angiopoietin (Ang) signaling plays a role in angiogenesis and remodeling of blood vessels through the receptor tyrosine kinase Tie2, which is expressed on blood vessel endothelial cells (BECs). Recently it has been shown that Ang-2 is crucial for the formation of lymphatic vasculature and that defects in lymphangiogenesis seen in Ang-2 mutant mice are rescued by Ang-1. These findings suggest important roles for Ang signaling in the lymphatic vessel system; however, Ang function in lymphangiogenesis has not been characterized. In this study, we reveal that lymphatic vascular endothelial hyaluronan receptor 1-positive (LYVE-1(+)) lymphatic endothelial cells (LECs) express Tie2 in both embryonic and adult settings, indicating that Ang signaling occurs in lymphatic vessels. Therefore, we examined whether Ang-1 acts on in vivo lymphatic angiogenesis and in vitro growth of LECs. A chimeric form of Ang-1, cartilage oligomeric matrix protein (COMP)-Ang-1, promotes in vivo lymphatic angiogenesis in mouse cornea. Moreover, we found that COMP-Ang-1 stimulates in vitro colony formation of LECs. These Ang-1-induced in vivo and in vitro effects on LECs were suppressed by soluble Tie2-Fc fusion protein, which acts as an inhibitor by sequestering Ang-1. On the basis of these observations, we propose that Ang signaling regulates lymphatic vessel formation through Tie2.  相似文献   
90.

Background

In 1999, the Japanese Orthopaedic Association decided to develop a new Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). The final version of the JOACMEQ, comprising 24 questions and five domains (cervical spine function (CF); upper extremity function (UF); lower extremity function (LF); bladder function (BF); and quality of life (QOL)), was established after three nationwide investigations. The fourth investigation, reported in this paper, was performed to confirm the responsiveness of the questionnaire.

Methods

A total of 137 patients with cervical myelopathy were included in the study. Each patient was interviewed twice using the JOACMEQ before and after treatment. At the second interview, the patients self-rated their condition in five domains for “worse,” “somewhat worse,” “no change,” “somewhat better,” or “better,” and these scores were defined as the external assessment rating. The difference of the points in five domains between the first and the second interview was calculated against each external assessment. Based on the results, substantial clinical benefit (SCB) thresholds for the JOACMEQ were determined.

Results

The statistically significant median values of the acquired points were 17.5 for CF, 16.0 and 21.0 for UF, 27.0 and 20.5 for LF, 13.0 for BF, and 29.0 for QOL. After consideration of the results, the committee decided that an acquired point ≥20 could be interpreted as representing an SCB threshold for the JOACMEQ.

Conclusion

We have concluded that a treatment can be judged to be effective for a patient if 1) The patient give all answers for the questions necessary to calculate the functional score of a domain and an increase of ≥20 points is obtained for that score, or 2) The functional score after treatment is > 90 points even if the answer for the unanswered questions was supposed to be the worst possible choice.  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