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   3881篇
  免费   212篇
  国内免费   26篇
耳鼻咽喉   23篇
儿科学   160篇
妇产科学   67篇
基础医学   436篇
口腔科学   84篇
临床医学   246篇
内科学   969篇
皮肤病学   67篇
神经病学   173篇
特种医学   197篇
外科学   821篇
综合类   14篇
预防医学   100篇
眼科学   104篇
药学   265篇
中国医学   31篇
肿瘤学   362篇
  2023年   26篇
  2022年   34篇
  2021年   114篇
  2020年   57篇
  2019年   83篇
  2018年   96篇
  2017年   84篇
  2016年   90篇
  2015年   119篇
  2014年   147篇
  2013年   159篇
  2012年   224篇
  2011年   274篇
  2010年   146篇
  2009年   146篇
  2008年   209篇
  2007年   264篇
  2006年   230篇
  2005年   240篇
  2004年   264篇
  2003年   216篇
  2002年   217篇
  2001年   59篇
  2000年   61篇
  1999年   39篇
  1998年   31篇
  1997年   32篇
  1996年   31篇
  1995年   29篇
  1994年   21篇
  1993年   12篇
  1992年   35篇
  1991年   25篇
  1990年   28篇
  1989年   21篇
  1988年   31篇
  1987年   22篇
  1986年   22篇
  1985年   29篇
  1984年   20篇
  1983年   17篇
  1982年   16篇
  1981年   7篇
  1980年   8篇
  1979年   12篇
  1978年   11篇
  1977年   7篇
  1976年   6篇
  1969年   7篇
  1968年   6篇
排序方式: 共有4119条查询结果,搜索用时 31 毫秒
81.
We report on a Japanese boy with Noonan syndrome who had short stature, bilateral cryptorchidism, poor pubertal development, mild mental retardation, complex cardiac lesions consisting of hypertrophic cardiomyopathy, mitral valve stenosis and insufficiency, subvalvular aortic stenosis, and single coronary artery, and various dysmorphic features including hypertelorism, epicanthic folds, low set malrotated ears, high arched palate, micrognathia, webbed neck, low posterior hairline, shield chest, pectus excavatum, cubitus valgus, borderline short metatarsals, lymphedema, redundant skin, and nail dysplasia. Because of marked lymphedema in the bilateral lower legs, lymphatic scintigraphy was carried out at 13.3 years of age, indicating extreme lymphstasis in the lower extremities, severe lymphstasis in the forearm, the elbow, and the axillary regions, moderate lymphstasis around the ascending aorta, and mild lymphstasis in the bilateral lungs. The results, in conjunction with those suggested in Turner syndrome, imply that lymphatic hypoplasia/dysplasia and resultant distended lymphatics and lymphedema are relevant to the development of not only soft tissue and visceral anomalies but also skeletal anomalies in Noonan syndrome.  相似文献   
82.
Long-term, low-dose erythromycin monotherapy, based on the anti-inflammatory effects of macrolides, has been reported to have the potential to suppress the exacerbation of Mycobacterium avium complex (MAC) lung disease with less toxicity. It remains unclear whether erythromycin monotherapy induces cross-resistance to clarithromycin, a key drug for MAC. To clarify this point, we conducted a retrospective, single-center, case-series study on patients with MAC lung disease who underwent erythromycin monotherapy for at least 6 months. Drug susceptibility tests, before and after erythromycin treatment initiation, were analyzed. Thirty-three patients were included in our study. All 33 patients showed susceptibility to clarithromycin for MAC both before and after erythromycin monotherapy. There was no significant difference in clarithromycin minimum inhibitory concentrations between before and after erythromycin treatment (median difference = 0 μg/ml; P = .313, Wilcoxon's signed-rank test). We conclude that erythromycin monotherapy for MAC lung disease may not induce cross-resistance to clarithromycin.  相似文献   
83.

Purpose

To evaluate the relationship between our proposed sonographic classification of testicular tumors by tissue harmonic imaging and histological type.

Methods

We retrospectively analyzed 58 testicular tumors and tumor-like lesions [seminomatous germ cell tumor (SGCT): 28; non-seminomatous germ cell tumor (NSGCT): 16; lymphoid and hematopoietic tumor (LHT): 7; Leydig cell tumor: 1; epidermal cyst: 2; and tumor of paratesticular structure (TPS): 4]. We divided a sonographic image into six types for morphological criteria and three types for color Doppler criteria. We examined the relationship between the sonographic classification and histological type.

Results

For morphological criteria, there were 21 cases of Type I (36%), 15 Type II (26%), 9 Type III (15%), five Type IV (9%), five Type V (9%), and three Type VI (5%). For color Doppler criteria, there were 47 cases classified as hypervascular (81%), eight as hypovascular (14%), and three as avascular (5%). Most of the SGCTs were divided into types I and II; the NSGCTs into types III, IV, and V; the LHTs into only type II; and the TPSs into type VI.

Conclusion

We established a sonographic classification of testicular tumors with various histological types. This sonographic classification is potentially useful for estimating the histological type of testicular tumors.
  相似文献   
84.

Purpose

Thiamine is an essential component of glucose metabolism and energy production. The disulfide derivative, thiamine tetrahydrofurfuryl disulfide (TTFD), is better absorbed than readily-available water-soluble thiamine salts because it does not require the rate-limiting transport system required for thiamine absorption. However, the detailed pharmacokinetics of thiamine and TTFD under normal and pathological conditions have not yet been clarified. C-11-labeled thiamine and TTFD were recently synthesized by our group. In this study, to clarify the differences in pharmacokinetics and metabolism of these probes, a quantitative PET imaging study and radiometabolite analysis of C-11-labeled thiamine and TTFD were performed in the rat heart.

Procedures

Positron emission tomography (PET) imaging with [11C]thiamine and [11C]TTFD was performed in normal rats to determine the pharmacokinetics of these probes, and the radiometabolites of both probes from the blood and heart tissue were analyzed by thin-layer chromatography.

Results

Accumulation of [11C]TTFD was significantly higher than that of [11C]thiamine in the rat heart. Moreover, as a result of the radiometabolite analysis of heart tissue at 15 min after the injection of [11C]TTFD, thiamine pyrophosphate, which serves as a cofactor for the enzymes involved in glucose metabolism, was found as the major radiometabolite and at a significantly higher level than in the [11C]thiamine-injected group.

Conclusions

PET imaging techniques for visualizing the kinetics and metabolism of thiamine using [11C]thiamine and [11C]TTFD were developed in this study. Consequently, noninvasive PET imaging for the pathophysiology of thiamine-related cardiac function may provide novel information about heart failure and related disorders.
  相似文献   
85.

Purpose

To investigate temporal variations in dispatcher-assisted and bystander-initiated resuscitation efforts and their association with survival after bystander-witnessed out-of-hospital cardiac arrests (OHCAs).

Methods

We retrospectively analyzed the neurologically favorable 1-month survival and the parameters related to dispatcher assisted cardiopulmonary resuscitation (DA-CPR) and bystander CPR (BCPR) for 227,524 OHCA patients between 2007 and 2013 in Japan. DA-CPR sensitivity for OHCAs, bystander's compliance to DA-CPR assessed by the proportion of bystanders who follow DA-CPR, and performance of BCPR measured by the rate of bystander-initiated CPR in patients without DA-CPR were calculated as indices of resuscitation efforts.

Results

Performance of BCPR was only similar to temporal variations in the survival (correlation between hourly paired values, R2 = 0.263, P = 0.01): a lower survival rate (3.4% vs 4.2%) and performance of BCPR (23.1% vs 30.8%) during night-time (22:00–5:59) than during non-night-time. In subgroup analyses based on interaction tests, all three indices deteriorated during night-time when OHCAs were witnessed by non-family (adjusted odds ratio, 0.73–0.82), particularly in non-elderly patients. The rate of public access defibrillation for these OHCAs markedly decreased during night-time (adjusted odds ratio, 0.49) with delayed emergency calls and BCPR initiation. Multivariable logistic regression analyses revealed that the survival rate of non-family-witnessed OHCAs was 1.83-fold lower during night-time than during non-night-time.

Conclusions

Dispatcher-assisted and bystander-initiated resuscitation efforts are low during night-time in OHCAs witnessed by non-family. A divisional alert system to recruit well-trained individuals is needed in order to improve the outcomes of night-time OHCAs witnessed by non-family bystanders.  相似文献   
86.
87.
We herein report a 65-year-old man with progressive multifocal leukoencephalopathy (PML) after 2-year remission from acute myeloid leukemia who developed recurrent episodes of left hemiparesis with gadolinium enhancement on magnetic resonance imaging. Steroid pulse therapy for each exacerbation induced clinical and radiological improvement, suggesting that exacerbations are an excessive immune response to the JC virus and distinct from immune reconstitution inflammatory syndrome (IRIS). Although glucocorticoids are recommended only for IRIS, steroid pulse therapy should be considered as a therapeutic option in cases of exacerbation of hematologic malignancy-associated PML. Importantly, neuroimaging is not sufficient to differentiate excessive inflammation from a controlled inflammatory response, for which steroids are not recommended.  相似文献   
88.
Journal of Gastroenterology - Following liver transplantation (LT), allograft liver failure can be developed by various causes and requires re-LT. Hence, this study aimed to clarify the...  相似文献   
89.
90.
We report 8 rare cases of primary lung cancer which showed a thin-walled cavity on chest X-ray and CT. We analyzed 8 cases (7 men, 1 woman) of primary lung cancer with thin-walled cavities admitted to our hospital between 1995 and 2006. The subjects were aged between 45 and 84 years of age (median: 72 years old). The reason for detection was treatment for tuberculosis in 1 case, ileus owing to metastasis to the small intestine in 1 case and tension pnumathorax 1 case, while 5 cases had abnormal chest x-ray film shadows without symptoms. Histologically, there were 5 cases of adenocarcinoma, 2 of squamous cell carcinoma, and 1 of adenosquamous cell carcinoma. Though various reports on the mechanism of the development of thin-walled cavity formation have been made, we suggest that it mainly develops by a check-valve mechanism, based on evaluation of the clinical course.  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