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   2079篇
  免费   99篇
  国内免费   31篇
耳鼻咽喉   27篇
儿科学   18篇
妇产科学   28篇
基础医学   234篇
口腔科学   47篇
临床医学   169篇
内科学   534篇
皮肤病学   87篇
神经病学   133篇
特种医学   101篇
外科学   318篇
综合类   13篇
预防医学   80篇
眼科学   48篇
药学   159篇
中国医学   7篇
肿瘤学   206篇
  2023年   8篇
  2022年   20篇
  2021年   39篇
  2020年   27篇
  2019年   28篇
  2018年   46篇
  2017年   34篇
  2016年   63篇
  2015年   65篇
  2014年   58篇
  2013年   104篇
  2012年   159篇
  2011年   126篇
  2010年   84篇
  2009年   70篇
  2008年   156篇
  2007年   144篇
  2006年   166篇
  2005年   140篇
  2004年   118篇
  2003年   123篇
  2002年   110篇
  2001年   20篇
  2000年   11篇
  1999年   13篇
  1998年   21篇
  1997年   12篇
  1996年   20篇
  1995年   18篇
  1994年   17篇
  1993年   6篇
  1992年   22篇
  1991年   9篇
  1990年   11篇
  1989年   12篇
  1988年   9篇
  1987年   10篇
  1986年   13篇
  1985年   14篇
  1984年   10篇
  1983年   8篇
  1982年   9篇
  1981年   6篇
  1980年   5篇
  1979年   3篇
  1978年   6篇
  1977年   7篇
  1976年   7篇
  1972年   3篇
  1965年   3篇
排序方式: 共有2209条查询结果,搜索用时 15 毫秒
991.
PURPOSE: Chronic maxillary sinusitis of dental origin (CMSDO) is a common disease that requires treatment of the sinusitis as well as of the odontogenic source. We present our surgical experience performing contemporary treatment of the odontogenic source and endoscopic sinus surgery (ESS) in patients with CMSDO. PATIENTS AND METHODS: Seventeen patients with CMSDO underwent contemporary treatment of the odontogenic source and ESS. Five patients presented chronic oroantral fistula (OAF); 5 patients presented odontogenic cysts occupying the maxillary sinus; 2 patients had inflammatory cysts of the molars; 2 patients had maxillary sinus infection secondary to peri-implantitis; 3 patients had foreign bodies pushed through the root canal into the sinus. The first surgical step was the treatment of the odontogenic source. The second step was ESS with opening and calibration of the maxillary natural ostium. RESULTS: Foreign bodies were extracted from the sinuses through the endonasal approach. No major complications after ESS were observed. The average time for ESS was +/-25 minutes. Good distant results without symptoms and complete closure of the fistula were obtained in all patients. CONCLUSION: When significant sinus disease is found, an endoscopic approach to drainage in all of the involved sinuses can promote predictably successful closure of OAF. The endoscopic approach to chronic maxillary sinusitis of dental origin is a reliable method associated with less morbidity and lower incidence of complications.  相似文献   
992.
PURPOSE: Tumor cell killing by anticancer drugs may be supported by their immuno- and pharmacologic effects. Chemotherapy is in fact able to (A) upregulate tumor-associated antigen expression, including carcinoembryonic antigen (CEA) or other target molecules such as thymidylate synthase (TS); and (B) downregulate tumor cell resistance to the death signals induced by tumor antigen-specific cytotoxic T lymphocytes. This provides the rationale for combining chemo- and immunotherapy. MATERIALS AND METHODS: We describe the results of a translational phase II trial designed to evaluate the toxicity, antitumor activity and immunologic effects of gemcitabine + FOLFOX-4 (oxaliplatin, fluorouracil, and folinic acid) polychemotherapy followed by the subcutaneous administration of granulocyte macrophage colony-stimulating factor and low-dose interleukin-2 in colorectal carcinoma patients. The study involved 29 patients (16 males and 13 females with a mean age of 69 years), 21 of whom had received a previous line of treatment, and 19 had liver involvement. RESULTS: The treatment was well tolerated and induced very high objective response (68.9%) and disease control rates (96.5%), with an average time to progression of 12.5 months. An immunologic study of peripheral blood mononuclear cells (PBMCs) taken from 20 patients showed an enhanced proliferative response to colon carcinoma antigen and a significant reduction in suppressive regulatory T lymphocytes (CD4+CD25T-reg+). A cytofluorimetric study of the PBMCs of five HLA-A(*)02.01+ patients who achieved an objective response showed an increased frequency of cytolytic T lymphocyte precursors specific for known CEA- and TS-derived epitopes. CONCLUSION: The results show that our regimen has strong immunologic and antitumor activity in colorectal cancer patients and deserves to be investigated in phase III trials.  相似文献   
993.
We have evaluated the effects of an ACE inhibitor, enalapril (ENA) and of an angiotensin II receptor blocker, losartan (LOS), administered either at hypotensive or non-hypotensive dosage, on the cardiac and renal structure of spontaneously hypertensive rats (SHR). Forty-eight rats were included in the study: eight SHR were treated with low-dose (ld, 1 mg/kg/day) ENA; eight with low-dose (ld, 0.5 mg/kg/day) LOS; eight with high-dose (hd, 25 mg/kg/day) ENA; eight with high-dose (hd, 15 mg/kg/day) LOS; while eight Wistar-Kyoto (WKY) and eight SHR were kept untreated (unt). Treatment was given from the 4th to the 12th week of age. Systolic blood pressure (SBP) was measured non-invasively every week. The left ventricular weight to body weight (RLVM) and the left + right kidney weight (RKW) to body weight was measured, and the cardiac and glomerular interstitial collagen content was evaluated using sirius red staining and image analysis. In addition, cardiac metalloproteinases activity (43 kDa MMP, MMP-2, and MMP-9) was evaluated by zymography. A significant reduction in RLVM was observed in SHR given ENA hd or LOS hd. Cardiac collagen was significantly reduced in SHR ENA hd and SHR LOS hd as well as in SHR LOS ld, but not in SHR ENA ld. The 43 kDa MMP collagenase activity was greater in WKY unt compared with SHR unt, being normalized only in SHR ENA hd. The gelatinase activity of MMP-9 showed a trend similar to 43 kDa MMP, but differences between SHR and WKY unt were only of borderline statistical significance. No difference among groups was observed in MMP-2 activity. No significant differences in RKW was observed between groups. However, the collagen content in the glomerular perivascular space was significantly reduced in all treated groups, including those given ld, compared with SHR unt. In conclusion, LOS and ENA showed a similar preventive effect on the increase of RLVM in SHR, but, at least in part, different effects on the extracellular matrix in different organs, being cardiac collagen less sensitive to low dose (ld) ACE inhibition.  相似文献   
994.
995.
996.
Loss of the tumor suppressor gene AT-rich interactive domain-containing protein 1A (ARID1A) has been demonstrated in several cancers, but its prognostic role is unknown. We aimed to investigate the risk associated with loss of ARID1A (ARID1A−) for all-cause mortality, cancer-specific mortality and recurrence of disease in subjects with cancer. PubMed and SCOPUS search from database inception until 01/31/2015 without language restriction was conducted, contacting authors for unpublished data. Eligible were prospective studies reporting data on prognostic parameters in subjects with cancer, comparing participants with presence of ARID1A (ARID1A+) vs. ARID1A−, assessed either via immunohistochemistry (loss of expression) or with genetic testing (presence of mutation). Data were summarized using risk ratios (RR) for number of deaths/recurrences and hazard ratios (HR) for time-dependent risk related to ARID1A− adjusted for potential confounders. Of 136 hits, 25 studies with 5,651 participants (28 cohorts; ARID1A−: n = 1,701; ARID1A+: n = 3,950), with a mean follow-up period of 4.7 ± 1.8 years, were meta-analyzed. Compared to ARID1A+, ARID1A− significantly increased cancer-specific mortality (studies = 3; RR = 1.55, 95% confidence interval (CI) = 1.19–2.00, I2 = 31%). Using HRs adjusted for potential confounders, ARID1A− was associated with a greater risk of cancer-specific mortality (studies = 2; HR = 2.55, 95%CI = 1.19–5.45, I2 = 19%) and cancer recurrence (studies = 10; HR = 1.93, 95%CI = 1.22–3.05, I2 = 76%). On the basis of these results, we have demonstrated that loss of ARID1A shortened time to cancer-specific mortality, and to recurrence of cancer when adjusting for potential confounders. For its role, this gene should be considered as an important potential target for personalized medicine in cancer treatment.  相似文献   
997.
998.
The aim of this study was the design of a 3D scaffold composed of poly(vinyl) alcohol (PVA) for cardiac tissue engineering (CTE) applications. The PVA scaffold was fabricated using a combination of gas foaming and freeze-drying processes that did not need any cross-linking agents. We obtained a biocompatible porous matrix with excellent mechanical properties. We measured the stress–strain curves of the PVA scaffolds and we showed that the elastic behavior is similar to that of the extracellular matrix of muscles. The SEM observations revealed that the scaffolds possess micro pores having diameters ranging from 10 μm to 370 μm that fit to the dimensions of the cells. A further purpose of this study was to test scaffolds ability to support human induced pluripotent stem cells growth and differentiation into cardiomyocytes. As the proliferation tests show, the number of live stem cells on the scaffold after 12 days was increased with respect to the initial number of cells, revealing the cytocompatibility of the substrate. In addition, the differentiated cells on the PVA scaffolds expressed anti-troponin T, a marker specific of the cardiac sarcomere. We demonstrated the ability of the cardiomyocytes to pulse within the scaffolds. In conclusion, the developed scaffold show the potential to be used as a biomaterial for CTE applications.

The aim of this study was the design of a 3D scaffold composed of poly(vinyl) alcohol (PVA) for cardiac tissue engineering (CTE) applications.  相似文献   
999.
Hepatitis B virus (HBV) transgenic mice (official designation, Tg [Alb-1 HBV] Bri 44) invariably develop macroscopically evident tumors within the 20th month of life. Sustained proliferative activity seems to play an important role in the development of these lesions. We previously showed that ursodeoxycholate (UDC) stimulates hepatocyte proliferation in various experimental settings. Herein, we tested the assumption that biological factors able to further increase liver cell proliferation, such as UDC, could accelerate tumor development in this animal model. For this study, 22 eight-week-old male transgenic mice were divided into 2 groups; 11 animals received a standard diet, and 11 received a UDC-enriched diet. The 2 groups were further divided into 2 subgroups of 5 and 6 animals each and were sacrificed at 3 and 15 months of age, respectively. These different times were chosen to exclude diet-related toxicity (in 3-month-old mice) and evaluate tumor growth (in 15-month-old mice). In addition, hepatocyte proliferation was assessed in all animals. In 3-month-old mice receiving UDC, cholestatic and cytolytic indices as well as liver histology were comparable to those in controls. At 15 months, all UDC-treated mice showed large multinodular tumors whereas only 33% of controls developed smaller uninodular neoplasms. Hepatocyte proliferation was increased in all animals receiving UDC compared with controls. In conclusion, the increase in serum UDC (undetectable in mice fed a standard diet), in the absence of any toxic effect on the liver, suggests the involvement of this bile salt in the stimulation of hepatocyte proliferation and tumor growth.  相似文献   
1000.
RESULTS: Twenty-one eyes and 22 eyes completed follow-up of 60mo in LASEK and PRK group respectively. Manifest refraction at 60mo follow-up was -0.01 and 0.26 in LASEK and PRK group respectively. In the LASEK group mean UDVA and mean CDVA after 60mo were 20/22 and 20/20 respectively (P>0.01). In the PRK group mean UDVA and mean CDVA at 60mo follow-up were 20/20 and 20/20 after 60mo (P>0.01). The efficacy indexes were 0.87 and 0.95, and the safety indexes were 1.25 and 1.4 respectively for LASEK group and PRK group.CONCLUSION:Both standard PRK and no-alcohol LASEK offer safe and effective correction of low-moderate myopia in the long term without any statistically significant difference between the two groups.  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