全文获取类型
收费全文 | 6154篇 |
免费 | 425篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 81篇 |
儿科学 | 181篇 |
妇产科学 | 114篇 |
基础医学 | 913篇 |
口腔科学 | 217篇 |
临床医学 | 517篇 |
内科学 | 1466篇 |
皮肤病学 | 135篇 |
神经病学 | 824篇 |
特种医学 | 117篇 |
外科学 | 611篇 |
综合类 | 18篇 |
预防医学 | 553篇 |
眼科学 | 118篇 |
药学 | 330篇 |
中国医学 | 19篇 |
肿瘤学 | 383篇 |
出版年
2023年 | 44篇 |
2022年 | 106篇 |
2021年 | 204篇 |
2020年 | 98篇 |
2019年 | 166篇 |
2018年 | 213篇 |
2017年 | 153篇 |
2016年 | 167篇 |
2015年 | 168篇 |
2014年 | 261篇 |
2013年 | 330篇 |
2012年 | 443篇 |
2011年 | 473篇 |
2010年 | 238篇 |
2009年 | 200篇 |
2008年 | 341篇 |
2007年 | 307篇 |
2006年 | 303篇 |
2005年 | 279篇 |
2004年 | 260篇 |
2003年 | 267篇 |
2002年 | 258篇 |
2001年 | 148篇 |
2000年 | 158篇 |
1999年 | 123篇 |
1998年 | 53篇 |
1997年 | 34篇 |
1996年 | 45篇 |
1995年 | 30篇 |
1994年 | 19篇 |
1993年 | 29篇 |
1992年 | 67篇 |
1991年 | 62篇 |
1990年 | 51篇 |
1989年 | 50篇 |
1988年 | 41篇 |
1987年 | 38篇 |
1986年 | 28篇 |
1985年 | 28篇 |
1984年 | 32篇 |
1983年 | 25篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 20篇 |
1977年 | 15篇 |
1975年 | 20篇 |
1974年 | 18篇 |
1973年 | 15篇 |
1972年 | 20篇 |
排序方式: 共有6597条查询结果,搜索用时 31 毫秒
1.
Rebecca L. King Albert C. Yan Debora R. Sekiguchi John K. Choi 《Journal of cutaneous pathology》2015,42(12):1012-1017
Reactive lymphoid infiltrates of the skin composed predominantly of gamma‐delta (γδ) T cells are not well described in the literature. Herein we report a case of an otherwise healthy 4‐year‐old male who presented with a waxing and waning papular rash characterized by small, discrete crusted papules spread across his trunk, face and extremities. Clinical evaluation revealed no evidence of systemic disease. Microscopic examination revealed a dermal, perivascular infiltrate of highly atypical lymphocytes with a γδ T cell phenotype, worrisome for primary cutaneous γδ T cell lymphoma. The clinical course, however, was that of a reactive condition and prompted consideration of a diagnosis of pityriasis lichenoides et varioliformis acuta (PLEVA) and lymphomatoid papulosis (LyP). In many ways, this case defies current classification schemes and seems to expand the spectrum of reactive γδ T cell infiltrates of the skin. 相似文献
2.
3.
Body weight and comorbidity predict mortality in COPD patients treated with oxygen therapy. 总被引:1,自引:0,他引:1
The aim of this study was to investigate the association between clinical variables and all-cause and respiratory mortality in patients with chronic obstructive pulmonary disease (COPD) undergoing long-term oxygen therapy (LTOT). The authors retrospectively studied a historic cohort of 128 patients with COPD (126 males, mean age+/-SD 68.9+/-9.7 yrs, body mass index (BMI) 25.1+/-4.5 kg.m-2, and forced expiratory volume in one second 25.4+/-8.8% predicted), who were being treated with long-term oxygen therapy in a tertiary teaching hospital between 1992 and 1999. Comorbidity, assessed with the Charlson Index, was present in 38% of the patients. Vital status and cause of death were assessed through the population death registry. A total of 78 patients (61%) had died by the end of follow-up. Three-year survival was 55%. Death was due to respiratory causes in 77% of cases. On Cox analysis, BMI<25 kg.m-2, comorbid conditions, age>or=70 yrs and cor pulmonale were associated with all-cause mortality. The BMI and comorbidity were the only significant predictive factors when the analysis was restricted to respiratory mortality. In conclusion, body mass index<25 kg.m-2 and comorbidity were predictors of all-cause and respiratory mortality in a cohort of chronic obstructive pulmonary disease patients treated with long-term oxygen therapy. These factors should be taken into account when considering the management and prognosis of these patients. 相似文献
4.
Hugo Maia Julio Casoy Tania Correia Luís Freitas Kleber Pimentel Célia Athayde Elsimar Coutinho 《Gynecological endocrinology》2006,22(10):547-551
OBJECTIVES: To determine whether aromatase expression in the eutopic endometrium and adenomyotic foci is affected by previous use of oral contraceptives containing gestodene, and to determine whether changes in cyclooxygenase-2 (COX-2) expression occur in adenomyosis during the menstrual cycle. PATIENT AND METHODS: This was a retrospective cohort study carried out in paraffin-embedded endometrial tissue obtained from patients with a histological diagnosis of adenomyosis obtained during the proliferative (n = 25) and luteal (n = 10) phases of the menstrual cycle and following the use of continuous oral contraception with gestodene/ethinyl estradiol (n = 7). COX-2 and aromatase expression were measured in both eutopic endometrium and adenomyotic foci using immunohistochemical methods. RESULTS: Aromatase expression was detected in 80% of the endometrial slices by immunohistochemistry. In positive cases, aromatase was mainly detected in the stromal cells of the eutopic endometrium, whereas in the adenomyotic foci this expression was negative in the majority of the cases. Oral contraceptives containing gestodene, on the other hand, were effective in suppressing aromatase expression in both eutopic and ectopic endometrium. COX-2 expression was detected by immunohistochemistry in the glandular epithelium of both eutopic endometrium and adenomyotic foci and there were no significant changes in its intensity throughout the menstrual cycle. CONCLUSION: Aromatase expression in the eutopic endometrium and adenomyotic foci is suppressed by oral contraceptives containing gestodene. Increased aromatase activity may be responsible for the persistent COX-2 expression during the luteal phase. 相似文献
5.
N M Alpert W C Barker A Gelman S Weise M Senda J A Correia 《Journal of cerebral blood flow and metabolism》1991,11(2):A26-A30
The limits of quantitation with positron emission tomography (PET) are examined with respect to the noise propagation resulting from radioactive decay and other sources of random error. Theoretical methods for evaluating the statistical error have been devised but seldom applied to experimental data obtained on human subjects. This paper extends the analysis in several ways: (1) A Monte Carlo method is described for tracking the propagation of statistical error through the analysis of in vivo measurements; (2) Experimental data, obtained in phantoms, validating the Monte Carlo method and other methods are presented; (3) A difference in activation paradigm, performed on regional CBF (rCBF) data from five human subjects, was analyzed on 1.6-cm diameter regions of interest to determine the mean fractional statistical error in PET tissue concentration and in rCBF before and after stereotactic transformation; and (4) A linear statistical model and calculations of the various statistical errors were used to estimate the magnitude of the subject-specific fluctuations under various conditions. In this specific example, the root mean squared (RMS) noise in flow measurements was about three times higher than the RMS noise in the concentration measurements. In addition, the total random error was almost equally partitioned between statistical error and random fluctuations due to all other sources. 相似文献
6.
Four cases of high-flow carotid-cavernous sinus fistula (CCF), three of them posttraumatic and one spontaneous, have been treated by a direct surgical approach to the cavernous sinus. The CCF's were obliterated by the introduction into the cavernous sinus of muscle fragments and/or fibrin sealant. In the three cases with a preoperatively patent internal carotid artery (ICA), the CCF was occluded and the ICA flow preserved. One of these also had a posttraumatic false aneurysm that enclosed the two avulsed ends of a transected intracavernous ICA. This was treated by cervical ICA ligation following resolution of the CCF. A fourth patient, who had previously undergone an unsuccessful ICA trapping procedure elsewhere, also obtained a good result. The case histories and the surgical technique are presented. Direct intracavernous obliteration with muscle fragments and fibrin sealant fulfills the criteria for treatment of high-flow CCF's: occlusion of the arteriovenous fistula and preservation of the ICA circulation. While this surgical technique is a therapeutic option in some cases, it appears to have precise indications in others. 相似文献
7.
Carlos Ferrer Albiach Antonio Conde Moreno Marta Rodríguez Cordón Virginia Morillo Macías Ana Bouché Babiloni Inmaculada Beato Tortajada Ángel Sánchez Iglesias Alicia Francés Muñoz 《Clinical & translational oncology》2010,12(1):22-26
Hypoxia is related to poor prognosis because it is associated to chemo-and radioresistance. During recent years the evolution
of imaging methods like PET/CT and MRI has meant the appearance of new perspectives with direct implications in radiation
therapy. We discuss previous experiences in staging, planning and in the follow-up process with these techniques for measuring
tumour hypoxia. 相似文献
8.
9.
10.
Cesar G. Victora Nubia Muoz Nicholas E. Day Lucio B. Barcelos Debora A. Peccin Noris M. Braga 《International journal of cancer. Journal international du cancer》1987,39(6):710-716
There is a cluster of high-incidence areas of oesophageal cancer in south-eastern South America, including Southern Brazil, Uruguay and parts of Argentina. The present case-control study investigated the hypothesis that this may be due to the drinking of maté, a traditional beverage drunk at a very high temperature, and also studied the role of other known risk factors such as alcohol and tobacco. Cases (171) and age- and sex-matched controls (342) were recruited from hospitals in the State of Rio Grande do Sul in Southern Brazil. The crude odds ratio for daily maté drinkers was 1.92 relative to those drinking less frequently than daily (p = 0.006). Other risk factors included the drinking of cachaça (a sugar cane spirit), smoking, rural residence, low fruit consumption and high intake of meats. After adjustment for these variables through conditional logistic regression, the odds ratio associated with daily maté drinking was reduced to 1.47 (90% CI = 0.87 - 2.50). Although the study failed to provide evidence of a strong association between maté and oesophageal cancer, the cluster of high rates could be explained by relative risks of the magnitude observed. This is due to the fact that approximately 70% of adult males and 50% of females are daily drinkers. In addition, this study revealed that alcohol, tobacco smoking and rural residence are the main risk factors for oesophageal cancer in this population and the fruit consumption confers some degree of protection. 相似文献