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   2275篇
  免费   88篇
  国内免费   16篇
耳鼻咽喉   39篇
儿科学   103篇
妇产科学   138篇
基础医学   286篇
口腔科学   39篇
临床医学   139篇
内科学   445篇
皮肤病学   58篇
神经病学   199篇
特种医学   50篇
外科学   118篇
综合类   14篇
一般理论   1篇
预防医学   232篇
眼科学   115篇
药学   255篇
中国医学   2篇
肿瘤学   146篇
  2024年   2篇
  2023年   18篇
  2022年   87篇
  2021年   117篇
  2020年   38篇
  2019年   55篇
  2018年   64篇
  2017年   51篇
  2016年   57篇
  2015年   75篇
  2014年   95篇
  2013年   106篇
  2012年   206篇
  2011年   204篇
  2010年   105篇
  2009年   88篇
  2008年   138篇
  2007年   123篇
  2006年   153篇
  2005年   148篇
  2004年   146篇
  2003年   120篇
  2002年   112篇
  2001年   8篇
  2000年   3篇
  1999年   11篇
  1998年   9篇
  1997年   6篇
  1996年   3篇
  1995年   4篇
  1994年   7篇
  1993年   2篇
  1992年   1篇
  1991年   2篇
  1989年   2篇
  1988年   2篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1982年   1篇
  1980年   1篇
  1977年   1篇
  1976年   1篇
  1968年   2篇
  1966年   1篇
排序方式: 共有2379条查询结果,搜索用时 15 毫秒
1.
PURPOSE: To evaluate the effect of lovastatin alone or combined with radiation on U87MG and FaDu cells in vitro and U87MG tumors in vivo. MATERIAL AND METHODS: Cell number, p21(WAF1) expression, apoptosis, reproductive cell death, and cell-cycle distribution were investigated after incubation of U87MG and FaDu cells in vitro. The effect of lovastatin (50 mg/kg/day) on tumor growth and on tumor growth delay after single-dose irradiation with 20 Gy was investigated using U87MG tumors in nude mice. RESULTS: Lovastatin dose dependently decreased cell number and proliferation of U87MG and FaDu cells. The proportion of cells in G0/G1 phase, apoptosis and p21 protein expression increased after lovastatin alone or combined with 4-Gy irradiation in both cell lines. Effects of lovastatin on cell cycle and cell number were more pronounced in U87MG compared to FaDu. No radiosensitization of clonogenic cells by lovastatin could be demonstrated in both cells lines, but the colony-forming ability after lovastatin alone was decreased in FaDu cells. In vivo, lovastatin decreased tumor volume over time but did not increase growth delay after irradiation of U87MG tumors with 20 Gy. CONCLUSION: The data support effects of lovastatin on proliferation, apoptosis and colony-forming ability in vitro and tumor volume in vivo. At the drug concentration achievable, lovastatin did not improve the effects of radiation on U87MG tumors in vivo.  相似文献   
2.
In the present study, morphological examination of patients from two unrelated Polish families with CADASIL was performed. Using light microscopy, there were evident changes characteristic to the disease. On electron microscopy, deposits of granular osmiophillic material (GOM) were found not only in cerebral arteries and veins but also in cerebral capillaries and vessels of the internal organs. These findings indicate that pathological process in CADASIL is generalized and involves also small vessels devoid of smooth muscle cells. Therefore, we propose to consider a replacement for the name CADASIL that better reflects the morphological picture of the disease like, for example, cerebral autosomal dominant vasculopathy with subcortical infarcts and leukoencephalopathy (CADVaSIL) or, to preserve the commonly known acronym, cerebral autosomal dominant angiopathy with subcortical infarcts and leukoencephalopathy.  相似文献   
3.
The double fluorescent retrograde technique was employed to examine the distribution of the inferior olive (IO) neurones projecting to the cortex of the rostral and caudal parts of the paramedian lobule (PML) in the rabbit cerebellum, known to be the face-forelimb and hindlimb receiving areas, respectively. Moreover, this technique was also used to investigate the possibility that IO projections reaching these two somatotopically non-homologous PML regions are collaterals of the same axones. No other reports have addressed this question. After non-overlapping unilateral injections of the cytoplasmic tracer fast blue (FB) and the nuclear dye diamidino yellow (DY) into the rostral and caudal PML, respectively, numerous single FB- or DY-labelled cells were found in the defined regions of the contralateral IO. These regions showed considerable overlap, apart from the dorsal accessory olive where a clear spatial separation of labelled cell groups was observed. Furthermore, double FB + DY-labelled neurones (n = 310) were seen in the medial accessory olive, the dorsal and ventral laminas of the principal olive, in the dorsomedial cell column and the beta nucleus. It suggests that IO neurones may branch to supply the two functionally different PML regions and in this way participate in the mechanisms of forelimb-hindlimb coordination.  相似文献   
4.
European Journal of Epidemiology - This essay considers the factors that have contributed to very high COVID-19 mortality in longer-term care facilities (LTCFs). We compare the demographic...  相似文献   
5.
BackgroundArteriovenous fistulae (AVFs) may remain patent after kidney transplantation (KTx), contributing to maladaptive cardiac remodeling. The flow in AVFs is associated with the diameter of its vessels and thus with the AVF location. The main objective of this study is to assess the influence of AVF location and its patency on the self-reported quality of life (QOL) of kidney transplant recipients (KTRs) with past history of hemodialysis.MethodsTo gain clinical data, during a scheduled visit, 353 KTRs were asked to fill out an anonymous questionnaire. From this group, 284 respondents were found eligible for analysis. The outcome was defined as prevalence of symptoms and health status, measured with the Left Ventricular Dysfunction-36 (LVD-36) Questionnaire in symptomatic patients.ResultsThe hemodialysis patients (n = 243) were divided into two groups according to AVF location, i.e., DAVF – distally located AVF – (n = 174) and PAVF – proximally located AVF – (n = 69). The proportion of patients with heart failure (HF) was higher in PAVF group (24% vs. 12%, p = 0.0482). In the multivariable regression, PAVF, serum creatinine levels, and the presence of HF or coronary artery disease (CAD) remained independent predictors of lower functional capacity. Among patients with heart disease, the presence of active AVF was independently associated with worse functional outcome (higher LVD-36 scores).ConclusionsThe influence of persistent PAVF in KTRs seems to be unfavorable, especially when coexisting with CAD or HF. Abbreviations: AVF arteriovenous fistula; BMI body mass index; CAD coronary artery disease; D-AVF distally-located arteriovenous fistula; EC exercise capacity; HD hemodialysis; HF heart failure; KTx kidney transplantation; KTR kidney transplant recipient; LVD-36 Left Ventricle Disfunction – 36; LVEF left ventricle ejection fraction; LVH left ventricle hypertrophy; NYHA New York Heart Association; P-AVF proximally located arteriovenous fistula; PD peritoneal dialysis; PRO patient-reported outcomes; QOL quality of life.  相似文献   
6.
7.
The aim of the study was a determination of the levels of nitric oxide(NO)and its biological markers such as malonyldialdehyde(MDA)and nitrotyrosine in the serum of patients with squamous cell carcinoma(SCC)of the oral cavity and identification of the relationships between NO and those markers.These studies were performed on patients with SCC of the oral cavity before and after treatment.Griess reaction was used for the estimation of the total concentration of NO in serum.The nitrotyrosine level in serum was assessed with an enzyme-linked immunosorbent assay(ELISA)kit,and MDA level using a spectrophotometric assay.Higher concentrations of NO in blood serum were determined in patients with stage IV of the disease before treatment in comparison to the control group and patients with stages II and III of the disease.Moreover,higher concentrations of MDA and nitrotyrosine were determined in the serum of patients in all stages of the disease in comparison to healthy people.After treatment,lower concentrations of NO in the serum of patients with stage IV of the disease were observed in comparison to the amounts obtained prior to treatment.In addition,lower levels of nitrotyrosine in the serum of patients with all stages of the disease were recorded,whereas higher concentrations of MDA were determined in these patients in comparison to results obtained before treatment.The compounds formed with the contribution of NO,such as MDA and nitrotyrosine,may lead to cancer progression in patients with SCC of the oral cavity,and contribute to formation of resistance to therapy in these patients as well.Moreover,the lack of a relationship between concentrations of NO and MDA,and between NO and nitrotyrosine in serum suggests that the process of lipid peroxidation and nitration in patients with SCC does not just depend on NO.  相似文献   
8.
Bezoars are the most common foreign bodies of gastrointestinal tract. They contain swallowed hair, different fibres, seeds, nut shells, sweets or drugs. Clinical manifestations vary, depending on the location and size of bezoar, from "no symptoms" to "acute abdomen" syndrome. In this case report, the authors describe a giant trichobezoar from the stomach of an 18-year-old girl, who had been admitted to the gynecological department with syndromes suggesting an ovarian cyst torsion. The preoperative diagnosis was not confirmed and a giant trichobezoar was found and removed during the surgery.  相似文献   
9.
10.
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