全文获取类型
收费全文 | 2067篇 |
免费 | 117篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 38篇 |
妇产科学 | 107篇 |
基础医学 | 186篇 |
口腔科学 | 56篇 |
临床医学 | 169篇 |
内科学 | 538篇 |
皮肤病学 | 58篇 |
神经病学 | 102篇 |
特种医学 | 74篇 |
外国民族医学 | 3篇 |
外科学 | 386篇 |
综合类 | 42篇 |
预防医学 | 78篇 |
眼科学 | 60篇 |
药学 | 192篇 |
中国医学 | 6篇 |
肿瘤学 | 100篇 |
出版年
2024年 | 2篇 |
2023年 | 32篇 |
2022年 | 60篇 |
2021年 | 136篇 |
2020年 | 68篇 |
2019年 | 93篇 |
2018年 | 128篇 |
2017年 | 90篇 |
2016年 | 71篇 |
2015年 | 57篇 |
2014年 | 102篇 |
2013年 | 180篇 |
2012年 | 177篇 |
2011年 | 176篇 |
2010年 | 100篇 |
2009年 | 87篇 |
2008年 | 107篇 |
2007年 | 113篇 |
2006年 | 88篇 |
2005年 | 89篇 |
2004年 | 67篇 |
2003年 | 63篇 |
2002年 | 60篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1933年 | 1篇 |
1927年 | 1篇 |
排序方式: 共有2204条查询结果,搜索用时 15 毫秒
1.
2.
3.
Ayman Agha Gabriel Glockzin Matthias Woenckhaus Wolfgang Dietmaier Igors Iesalnieks Hans J. Schlitt 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》2007,392(6):671-677
Background Insular thyroid carcinoma was described as a tumor with aggressive behavior, and patients usually present themselves with
an advanced tumor stage. Whether the insular component is an independent factor for poor prognosis remains unclear. Therefore,
in the present study, we compared the survival of patients with advanced insular, follicular, and papillary thyroid cancer.
Materials and methods The clinical behavior of tumors in three groups of patients with T4 thyroid carcinoma—8 patients with insular, 11 patients
with follicular, and 21 patients with papillary thyroid carcinomas—was compared. Disease-free survival and disease-specific
death were analyzed statistically. Cox regression analysis was used to evaluate the influence of histotype and other prognostic
factors.
Results At 3 years, survival was 37.5% (mean 26 months) among patients with insular thyroid carcinoma, 80% (mean 59 months) among
those with follicular, and 89% (mean 126 months) among those with papillary thyroid carcinomas (p = 0.007). Disease-free survival in patients without initial distant metastasis was worst in patients with insular thyroid
carcinoma (20%) compared to those with follicular (75%) and those with papillary thyroid carcinomas (71%).
Conclusion Patients with advanced insular thyroid carcinoma have a poorer outcome in comparison to patients with similar advanced stage
who have follicular or papillary thyroid carcinoma. 相似文献
4.
Phyllis W Sharps Ayman A E El-Mohandes M Nabil El-Khorazaty Michele Kiely Tessa Walker 《Journal of perinatology》2003,23(5):414-419
OBJECTIVE: To describe breastfeeding initiation among 210 urban African-American mothers with inadequate prenatal care. METHODS: This study is a case-control study of postpartum mothers recruited from four large urban hospitals. RESULTS: Mothers who chose to breastfeed were more educated, employed before birth, married, and using contraception postnatally. Regression model analysis controlling for demographic differences revealed that breastfeeding was significantly associated with a higher perception of severity of illness and higher confidence in the ability of health care to prevent illness. Breastfeeding mothers were less likely to reverse parent-child roles and had a lower perception of hassle from their infant's behavior. When comparing mothers who breastfed longer than 8 weeks to those who did not breastfeed, breastfeeding mothers had high scores related to empathy toward infants on the Adult-Adolescent Parenting Inventory as well as a low perception of hassle on the Parenting Daily Hassle. The perception of existing formal or informal social support did not influence breastfeeding behavior. CONCLUSION: Personal attributes of low-income urban mothers such as health beliefs and parental attitudes may play a role in the initiation and duration of breastfeeding. Low-income African-American mothers may be influenced in their choice to breastfeed by supportive messages from physicians and nurses delivering care to mothers and their newborns. Emphasis should be placed on the role breastfeeding can play in preventing childhood illnesses. 相似文献
5.
Ayman A Abdo Stefan J Urbanski Paul L Beck 《Journal canadien de gastroenterologie》2003,17(7):425-432
Microscopic colitis (MC) encompasses the two morphologically distinct entities of collagenous colitis (CC) and lymphocytic colitis (LC). MC was first described less than 30 years ago but is presently recognized as a relatively common cause of chronic diarrhea in the adult population. Remarkably, up to 10% of adults who have a colonoscopy for the investigation of chronic diarrhea, and have endoscopically normal appearing mucosa, may have MC. Patients with MC generally present with chronic diarrhea, which can be associated with cramping and bloating. Endoscopic and radiological examinations are usually normal. Histological assessment reveals inflammation consisting predominantly of lymphocytic infiltration, and a thickened subepithelial collagen band is diagnostic of CC. Both LC and CC can be associated with autoimmune diseases such as celiac disease, diabetes, arthritis and thyroiditis, yet the mechanisms involved in the pathogenesis remain unclear. Emerging studies suggest that a stepwise approach be taken in the medical management of MC. This approach includes antidiarrheal agents and stopping of any offending agents; budesonide or bismuth subsalicylate; and cholestyramine or 5-acetylsalicylic acid agents. In resistant cases, oral corticosteroids and other immune modulatory therapy have been used. 相似文献
6.
Melissa R. Riester Elliott Bosco Barbara H. Bardenheier Patience Moyo Rosa R. Baier Melissa Eliot Joe B. Silva Stefan Gravenstein Robertus van Aalst Ayman Chit Matthew M. Loiacono Andrew R. Zullo 《Journal of the American Medical Directors Association》2021,22(6):1271-1278.e3
ObjectivesQuantify how observable characteristics contribute to influenza vaccination disparities among White, Black, and Hispanic nursing home (NH) residents.DesignRetrospective cohort.Setting and ParticipantsShort- and long-stay U.S. NH residents aged ≥65 years.MethodsWe linked Minimum Data Set (MDS) and Medicare data to LTCFocUS and other facility data. We included residents with 6-month continuous enrollment in Medicare and an MDS assessment between October 1, 2013, and March 31, 2014. Residents were classified as short-stay (<100 days in NH) or long-stay (≥100 days in NH). We fit multivariable logistic regression models to assess the relationships between 27 resident and NH-level characteristics and receipt of influenza vaccination. Using nonlinear Oaxaca-Blinder decomposition, we decomposed the disparity in influenza vaccination between White versus Black and White versus Hispanic NH residents. Analyses were repeated separately for short- and long-stay residents.ResultsOur study included 630,373 short-stay and 1,029,593 long-stay residents. Proportions vaccinated against influenza included 67.2% of White, 55.1% of Black, and 54.5% of Hispanic individuals among short-stay residents and 84.2%, 76.7%, and 80.8%, respectively among long-stay residents. Across 4 comparisons, the crude disparity in influenza vaccination ranged from 3.4 to 12.7 percentage points. By equalizing 27 prespecified characteristics, these disparities could be reduced 37.7% to 59.2%. Living in a predominantly White facility and proxies for NH quality were important contributors across all analyses. Characteristics unmeasured in our data (eg, NH staff attitudes and beliefs) may have also contributed significantly to the disparity.Conclusions and ImplicationsThe racial/ethnic disparity in influenza vaccination was most dramatic among short-stay residents. Intervening on factors associated with NH quality would likely reduce these disparities; however, future qualitative research is essential to explore potential contributors that were unmeasured in our data and to understand the degree to which these factors contribute to the overall disparity in influenza vaccination. 相似文献
7.
Heinrich Heimann Norbert Bornfeld Wilko Friedrichs Horst Helbig Ulrich Kellner Ayman Korra Michael H. Foerster 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》1996,234(9):561-568
Background: Pars planta vitrectomy has evolved as an alternative method in the treatment of more complicated rhegmatogenous retinal detachments. We report a series of patients who underwent primary vitrectomy with gas tamponade without the use of additional scleral buckling. Methods: A retrospective study of 53 patients with a follow-up of 6–45 months (mean 17.8 months) was carried out. Preoperative findings included unusual, multiple or large breaks, vitreous haemorrhage, proliferative vitreoretinopathy and bullous retinal detachment. Preoperative visual acuity was between light perception and 1.0, with 30% (16/53) of patients with 0.4 or better. Results: Retinal reattachment was achieved in 64% of cases (34/53) with one and in 92% (49/53) with one or more operations. Final visual acuity was between light perception and 1.0, with 41% (22/53) of patients with 0.4 or better. Cataract formation occurred in 86% (37/43) of all patients with a clear lens preoperatively. Macular pucker was noted in 11 % (6/53) and postoperative proliferative vitreoretinopathy causing redetachment in 6% (3/53). Conclusion: With primary vitrectomy, a high final anatomical success rate with few intraoperative complications can be achieved in more complicated forms of rhegmatogenous retinal detachment. The major drawback of the procedure is the high incidence of post-operative cataract formation. 相似文献
8.
Evaluation of osteopontin as biomarker for pancreatic adenocarcinoma. 总被引:19,自引:0,他引:19
Jens Koopmann Neal S Fedarko Alka Jain Anirban Maitra Christine Iacobuzio-Donahue Ayman Rahman Ralph H Hruban Charles J Yeo Michael Goggins 《Cancer epidemiology, biomarkers & prevention》2004,13(3):487-491
OBJECTIVES: Pancreatic adenocarcinoma is a deadly disease with an overall 5-year patient survival of less than 5%. This dismal prognosis of pancreatic cancer is largely due to the advanced stage of the disease at presentation. If pancreatic cancer could be diagnosed more readily and accurately using serum markers, patient survival could theoretically be improved by enabling more patients to avail of surgical resection. One candidate tumor marker recently identified by global gene expression analysis of pancreatic cancer is the secreted glycophosphoprotein osteopontin (OPN). In this study, we evaluate OPN as a serum marker of pancreatic adenocarcinoma. METHODS: In situ hybridization for OPN was performed on a pancreatic adenocarcinoma tissue microarray. Serum OPN levels were determined in preoperative sera from 50 patients with pancreatic cancer and 22 healthy control individuals by competitive ELISA. RESULTS: In situ hybridization for OPN performed on a tissue microarray revealed strong OPN mRNA signal in tumor-infiltrating macrophages in 8 of 14 pancreatic adenocarcinomas. In contrast, OPN expression was not seen in the pancreatic cancer cells themselves, nor was it seen in normal pancreatic tissue or in the macrophages distant from the infiltrating cancer. Serum OPN levels, as measured by ELISA, were elevated in the sera of 50 patients with resectable pancreatic adenocarcinoma compared to 22 healthy control individuals (mean +/- SD for OPN was 482 +/- 170 ng/ml and 204 +/- 65 ng/ml, respectively; P < 0.001). Using a cutoff level of 2 SD above the mean for healthy individuals, elevated OPN had sensitivity of 80% and specificity of 97% for pancreatic cancer. In contrast, only 62% of these patients with resectable pancreatic cancer had elevated CA19-9. CONCLUSIONS: Serum OPN may have utility as a diagnostic marker in patients with pancreatic cancer. 相似文献
9.
Donna E. Hansel Ayman Rahman Robb E. Wilentz Ie-ming Shih Michael T. McMaster Charles J. Yeo Anirban Maitra MD 《Journal of gastrointestinal cancer》2005,35(1):15-23
HLA-G belongs to the nonclassical MHC class Ib group of molecules and has been implicated in mediating immune-responsiveness in various cancerous and non-cancerous cell types. We have examined HLA-G expression in a number of human gastrointestinal malignancies, including pancreatic ductal adenocarcinoma, ampullary cancer, biliary cancer, and colorectal cancer by immunolabeling analysis. We used indices of <5% (negative), 6–25%, 26–50%, 51–75%, and >75% (diffuse) to subclassify lesions based on percentage of positive cell labeling. Across all cancer subtypes, 52–79% of lesions demonstrated expression of HLA-G, with up to 33% of lesions demonstrating diffuse (>75%) expression. In addition, we utilized the neoplastic progression model of colorectal cancer to evaluate HLA-G protein expression in normal colon, tubulovillous adenomas, invasive cancer, and liver metastases arising from colorectal cancer. Focal HLA-G expression was detected in regions of normal colon adjacent to sites of adenomatous and cancerous lesions, as well as in all stages of cancer progression. Overall, the percentage of diffusely (>75%) labeled lesions appeared increased in preneoplastic and neoplastic conditions, as compared to normal colon. Specifically, tubulovillous adnenomas demonstrated pronounced diffuse labeling in 58% of lesions examined. No correlation with HLA-G expression and CD4+ or CD8+ T cells was identified. We propose that HLA-G expression is upregulated in a large percentage of gastrointestinal lesions and may serve to mediate immuneresponsiveness in certain instances. 相似文献
10.
Evaluation of the anti-inflammatory, anti-nociceptive and gastric effects of Ginkgo biloba in the rat. 总被引:2,自引:0,他引:2
Omar M E Abdel-Salam Ayman R Baiuomy Seham El-batran Mahmoud S Arbid 《Pharmacological research》2004,49(2):133-142
Ginkgo biloba extract (GbE) was assessed in models of acute inflammation induced by carrageenan, formalin or capsaicin in the rat, in models of nociceptive pain, such as hot-plate (55 degrees C) latency, tail-electric stimulation assay and capsaicin-induced paw licking and in the model of acute gastric damage induced by indomethacin. The agent showed marked anti-inflammatory activity in the carrageenan model of paw oedema. When given subcutaneously (s.c.) (25 and 50 mg kg(-1)) 30 min before challenge, GbE inhibited paw oedema with a maximal effect of 43.7 and 56.9%, respectively, at 2h post-carrageenan. Significant inhibition of oedema was also observed when GbE (50 mg kg(-1), s.c.) was given 30 min after carrageenan challenge. The agent was also active p.o. in acute inflammation caused by carrageenan. The administration of GbE with indomethacin, rofecoxib, celecoxib, dexamethasone or melatonin resulted in an additive effect. GbE (50 mg kg(-1), s.c.) caused significant inhibition of formalin-induced paw oedema, but did not reduce the capsaicin-induced paw oedema. In tests of nociception, GbE (25, 50 or 100 mg kg(-1)) decreased in dose-dependent manner the capsaicin-induced hind paw licking time and was similarly effective in the hot-plate assay of nociception. In contrast, when assessed in the tail-electric stimulation test, GbE was only effective in the highest dose (100 mg kg(-1)). In pylorus-ligated rats, GbE (25 or 50 mg kg(-1)) increased gastric acid secretion, but reduced gastric mucosal damage caused by IND. Results suggest that GbE may be of clinical value as an anti-inflammatory and analgesic drug alone or in conjunction with NSAIDs. 相似文献