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   1317篇
  免费   64篇
  国内免费   90篇
耳鼻咽喉   4篇
儿科学   62篇
妇产科学   46篇
基础医学   130篇
口腔科学   20篇
临床医学   257篇
内科学   248篇
皮肤病学   78篇
神经病学   88篇
特种医学   111篇
外科学   126篇
综合类   62篇
预防医学   77篇
眼科学   10篇
药学   98篇
中国医学   3篇
肿瘤学   51篇
  2022年   9篇
  2021年   16篇
  2020年   15篇
  2019年   19篇
  2018年   17篇
  2017年   20篇
  2016年   17篇
  2015年   22篇
  2014年   51篇
  2013年   47篇
  2012年   46篇
  2011年   49篇
  2010年   53篇
  2009年   38篇
  2008年   35篇
  2007年   85篇
  2006年   29篇
  2005年   39篇
  2004年   23篇
  2003年   25篇
  2002年   32篇
  2001年   26篇
  2000年   24篇
  1999年   20篇
  1998年   36篇
  1997年   52篇
  1996年   35篇
  1995年   41篇
  1994年   36篇
  1993年   28篇
  1992年   19篇
  1991年   11篇
  1990年   26篇
  1989年   36篇
  1988年   24篇
  1987年   17篇
  1986年   18篇
  1985年   15篇
  1984年   10篇
  1983年   13篇
  1982年   11篇
  1981年   14篇
  1977年   12篇
  1976年   15篇
  1968年   8篇
  1966年   9篇
  1965年   12篇
  1963年   11篇
  1959年   13篇
  1956年   8篇
排序方式: 共有1471条查询结果,搜索用时 0 毫秒
31.
32.
The immunohistochemical expression of p53 and c-erbB-2 gene proteins was examined in a series of 130 breast adenocarcinomas. This study intended to investigate whether the frequency of the altered expression of the tumour suppressor gene p53 and the overexpression of the oncogene c-erbB-2 in breast cancer tissue cells correlated with other variables known to affect the biological behaviour of these tumours and the overall survival of the patients (median follow-up time: 6 years). The expression of p53 protein and c-erbB-2 gene product was evaluated immunohistochemically. Expression of p53 protein was detected in 30 (23 per cent) of the neoplasms examined, while 26 (20 per cent) out of the 130 cases demonstrated positive c-erbB-2 immunoreactivity. There was a statistically significant association between p53 protein expression and primary tumour size, lymph node involvement, and oestrogen receptor positivity. The incidence of c-erbB-2 positivity was significantly correlated with high tumour grade, axillary node invasion, large tumour size, and the absence of steroid receptors. p53 immuno-expression was clearly associated with c-erbB-2 protein overexpression. Concomitant p53 and c-erbB-2 positive immunolabelling, which emerged in 14 out of the 130 cases (10·7 per cent), was clearly associated with high grade, large size, positive nodal status, ductal infiltrating (NOS) histological type, and low values of progesterone receptors. Overall survival of patients was not significantly related to the immunoreactivity of either p53 or c-erbB-2 considered separately, whereas there was a clearly significant trend to worse overall prognosis in cancers with double p53/c-erbB-2 positive phenotype. The simultaneous immunodetection of p53/c-erbB-2 appears to have greater negative prognostic relevance than their separate expression.  相似文献   
33.
The hammerhead ribozyme is a small catalytic RNA molecule. Potential hammerhead ribozymes that possess a catalytic domain and flanking sequence complementary to a target mRNA can cleave in trans at a putative cleavage site within the target molecule. We have investigated the potential of hammerhead ribozymes to down-regulate the product of the fibrillin-1 gene (FBN1). Fibrillin is a 347 kDa glycoprotein that is a major constituent of the elastin-associated microfibrils. Mutations in the FBN1 gene are responsible for Marfan syndrome (MFS), a common systemic disorder of the connective tissue. Many FBN1 mutations responsible for MFS appear to act in a dominant-negative fashion, raising the possibility that reduction of the amount of product from the mutant FBN1 allele might be a valid therapeutic approach for MFS. A trans-acting hammerhead ribozyme (FBN1-RZ1) targeted to the 5' end of the human FBN1 mRNA has been designed and synthesized, and shown to cleave its target efficiently in vitro. FBN1-RZ1 cleavage is magnesium dependent and efficient at both 37 and 50 degrees C. Delivery of the FBN1-RZ1 ribozyme into cultured dermal fibroblasts, by receptor- mediated endocytosis of a ribozyme-transferrin-polylysine complex, specifically reduces both cellular FBN1 mRNA and the deposition of fibrillin in the extracellular matrix. These results suggest that the use of hammerhead ribozymes is a valid approach to the study of fibrillin gene expression and possibly to the development of a therapeutic approach to MFS.   相似文献   
34.
The National Cholesterol Educational Program Adult Treatment Panel's third report define borderline-high, high, and very high triglycerides as serum levels of 150–199 mg/dL, 200–499 mg/dL, and ≥500 mg/dL, respectively. Hypertriglyceridemia (HTG) is generally very responsive to both therapeutic lifestyle changes (TLC), and drug therapy, with niacin, omega-3 fatty acids, fibrates, and statins, each reducing levels by ~10–50%. This paper presents two cases of patients who were aggressively treated for significant HTG with little response to therapy. Although most measured triglyceride (TG) values in these patients were markedly elevated, periodic concentrations were reported as normal. When this occurs, the clinician must immediately think of the diagnosis ‘pseudohypertriglyceridemia’ or as it is more aptly termed ‘glycerolemia’ secondary to glycerol kinase deficiency (GKD).  相似文献   
35.
Polymorphism of the thiopurine S-methyltransferase gene in African- Americans   总被引:12,自引:0,他引:12  
The molecular basis for the genetic polymorphism of thiopurine S - methyltransferase (TPMT) has been estab-lished for Caucasians, but it remains to be elucidated in African populations. In the current study, we determined TPMT genotypes in a population of 248 African-Americans and compared it with allele frequencies in 282 Caucasian Americans. TPMT genotype was determined in all individuals with TPMT activity indicative of a heterozygous genotype (</=10.1 U/ml pRBC, n = 23African- Americans, n = 21 Caucasians) and a control group with TPMT activity indicative of a homozygous wild-type genotype (>10.2 U/ml pRBC, n = 23 African-Americans, n = 21 Caucasians). No mutant alleles were found in the high activity control groups. The overall mutant allele frequencies were similar in African-Americans and Caucasians (4.6 and 3.7% of alleles, respectively). However, while TPMT*3C was the most prevalent mutant allele in African-Americans (52.2% of mutant alleles), it represented only 4.8% of mutant alleles in Caucasians ( P < 0.001). In contrast, TPMT*3A and TPMT*2 were less common in African-Americans (17.4 and 8.7% of mutant alleles), whereas TPMT*3A was the most prevalent mutant allele in Caucasians (85.7% of mutant alleles). A novel allele ( TPMT*8 ), containing a single nucleotide transition (G644A), leading to an amino acid change at codon 215 (Arg-->His), was found in one African-American with intermediate activity. These data indicate that the same TPMT mutant alleles are found in American black and white populations, but that the predominant mutant alleles differ in these two ethnic groups.   相似文献   
36.
Champion KJ, Bunag C, Estep AL, Jones JR, Bolt CH, Rogers RC, Rauen KA, Everman DB. Germline mutation in BRAF codon 600 is compatible with human development: de novo p.V600G mutation identified in a patient with CFC syndrome. BRAF, the protein product of BRAF, is a serine/threonine protein kinase and one of the direct downstream effectors of Ras. Somatic mutations in BRAF occur in numerous human cancers, whereas germline BRAF mutations cause cardio‐facio‐cutaneous (CFC) syndrome. One recurrent somatic mutation, p.V600E, is frequently found in several tumor types, such as melanoma, papillary thyroid carcinoma, colon cancer, and ovarian cancer. However, a germline mutation affecting codon 600 has never been described. Here, we present a patient with CFC syndrome and a de novo germline mutation involving codon 600 of BRAF, thus providing the first evidence that a pathogenic germline mutation involving this critical codon is not only compatible with development but can also cause the CFC phenotype. In vitro functional analysis shows that this mutation, which replaces a valine with a glycine at codon 600 (p.V600G), leads to increased ERK and ELK phosphorylation compared to wild‐type BRAF but is less strongly activating than the cancer‐associated p.V600E mutation.  相似文献   
37.
ObjectivesTo evaluate surgical complexity scores (SCS) and minimally invasive surgery (MIS) at interval debulking surgery (IDS) in advanced epithelial ovarian cancer (EOC) patients receiving neoadjuvant chemotherapy (NACT).MethodsA multi-institutional study of NACT with IDS for advanced EOC was conducted. Demographic data were abstracted and SCS assigned based on IDS findings. Disease-specific overall survival (DSS) was defined as the time from completion of adjuvant chemotherapy to death due to disease. Cox proportional hazards regression models were used for univariate and multivariate survival analyses.Results282 patients were identified; 80.5% had high-grade serous histology and 54.6% were <75 (median 63.9; range 34.1–84.8). Approximately 84% were optimally cytoreduced (61% R0; 23% <1 cm). In multivariate analyses, age 75+ (p ≤ 0.001), residual disease (>1 cm; p = 0.03), and SCS ≥ 3 (p = 0.04) were significantly predictive of worse DSS when morbidity and ASA score were also in the model. When optimally debulked was defined as R0, only age 75+ (<0.001) was significantly associated with decreased DSS. In the R0 cohort, SCS did not significantly predict DSS. However, subset analysis defining optimal ≤1 cm, revealed higher SCS was associated with a 1.6-fold increased risk of death (p = 0.02).Fifty-one patients underwent laparoscopic IDS. Twenty-four (47%) were converted to laparotomy to achieve optimal debulking in 21 patients (87.5%); while 25 had laparoscopic optimal cytoreduction (19/25 [76%] R0).ConclusionsIn women with advanced EOC treated with NACT, older age, SCS ≥ 3, and residual disease >1 cm at IDS were predictors of worse survival. MIS appears safe and feasible with acceptable optimal cytoreduction rates.  相似文献   
38.
MircoRNAs as a new class of regulatory molecules have been investigated in many specific cells and organs in healthy and diseased conditions. Although miRNA signatures can be directly assessed in patients' affected tissues such as tumor sections, recent studies revealed that miRNA profiles can also be obtained indirectly, that is, from the patients' peripheral blood. For better understanding of miRNA's contribution to gastric carcinoma (one of the leading causes of cancer‐related mortality worldwide), we screened for deregulated miRNAs in blood collected from human cancer patients and compared the expression patterns with a gastric carcinoma mouse model (Tff1 knock‐out). The profiles were assessed using species‐specific miRNA microarrays. Among many dozens of deregulated miRNAs (219 in H. sapiens; 75 in M. musculus), a subset of eight miRNAs comparable in sequence from both species was noted. By in silico analysis, their involvement in targeting neoplastic and MAPkinase pathways was demonstrated. We found a high probability of linkage of all noted miRNAs to pathways in cancer with P‐values of 0.013 and 0.018 in mice and humans, respectively. Linkage to the MAPK‐signaling pathway in mice was observed with a P‐value of 0.01. Moreover, when comparing the 219 deregulated miRNAs obtained from blood with deregulated miRNAs derived from gastric cancer (GC) tissues, as published previously, 24 miRNAs were identical. If confirmed in a larger patient pool, these miRNAs could constitute appropriate blood‐born biomarkers for GC. © 2012 Wiley Periodicals, Inc.  相似文献   
39.
4分子治疗分析肿瘤细胞中的分子遗传性变异及后天变异的方法正在快速成熟起来。这些方法通常涉及基因组学、转录特征性识别及蛋白质组学,有利于更深入地了解ALL的发病机理,使用于临床评估的靶向治疗全面发展。最终,这些层出不穷的新技术将营造出一个全新的个性化分子医学时代,创造出效果更好而毒性更低的治疗方案。尽管治疗方案均显示了药物介入控制细胞周期进程、基因转录、细胞运动、凋亡及细胞代谢信号通路的可行性(图1),但针对ALL的分子治疗情况(表1)仍差强人意。我们将从众多正处于临床前期或早期临床研究的分子治疗方案中,选择出那…  相似文献   
40.

Objective

To determine whether intra-operative radiation therapy (IORT) at the time of pelvic exenteration (PE) or laterally extended endopelvic resection (LEER) improves progression-free survival (PFS) in patients with recurrent, previously irradiated gynecologic cancers.

Methods

We conducted a single institution retrospective review of patients who had undergone a complete PE for locally recurrent gynecologic cancer. Demographic and clinicopathologic data were collected.

Results

32 patients were identified (2000–2012); 21 (66%) cervical cancer, 8 (25%) vaginal, and 3 (9%) vulvar cancer. All patients were previously irradiated. Twenty-one (66%) received IORT. Mean age was 51. Eight patients had a LEER, all with IORT. Median PFS and OS, respectively, for those with PE alone was 33 and 41 vs. 10 and 10 months for PE + IORT compared to 9 and 17 months for LEER + IORT (P = .04). Increasing tumor size negatively impacted PFS (hazard ratio 1.3; 95%CI 1.12–1.52). Margin status was not associated with survival. No patients undergoing LEER + IORT recurred only locally whereas 62% recurred with a distant component (+/− local). Patients with PE alone had mainly local (36%) and few (9%) distant recurrences compared to 31% local and 38% distant (+/− local) recurrences for those with PE + IORT.

Conclusions

We failed to demonstrate that IORT changes survival and recurrence outcomes. However, patients with clinical indications for IORT at the time of PE have worse prognosis compared to those who do not require IORT. If the need for IORT is anticipated, the surgeon may consider performing a LEER to decrease local recurrence if cure is the goal or consider palliative treatment options.  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