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   14268篇
  免费   992篇
  国内免费   32篇
耳鼻咽喉   120篇
儿科学   431篇
妇产科学   508篇
基础医学   2115篇
口腔科学   242篇
临床医学   1806篇
内科学   2500篇
皮肤病学   409篇
神经病学   1369篇
特种医学   272篇
外科学   1283篇
综合类   100篇
一般理论   43篇
预防医学   1601篇
眼科学   237篇
药学   1041篇
中国医学   24篇
肿瘤学   1191篇
  2024年   14篇
  2023年   141篇
  2022年   329篇
  2021年   560篇
  2020年   277篇
  2019年   494篇
  2018年   521篇
  2017年   353篇
  2016年   458篇
  2015年   442篇
  2014年   617篇
  2013年   779篇
  2012年   1116篇
  2011年   1190篇
  2010年   644篇
  2009年   528篇
  2008年   885篇
  2007年   923篇
  2006年   898篇
  2005年   830篇
  2004年   720篇
  2003年   636篇
  2002年   614篇
  2001年   91篇
  2000年   84篇
  1999年   87篇
  1998年   114篇
  1997年   80篇
  1996年   73篇
  1995年   62篇
  1994年   74篇
  1993年   51篇
  1992年   50篇
  1991年   50篇
  1990年   34篇
  1989年   42篇
  1988年   39篇
  1987年   20篇
  1986年   25篇
  1985年   34篇
  1984年   33篇
  1983年   29篇
  1982年   30篇
  1981年   36篇
  1980年   31篇
  1979年   19篇
  1978年   19篇
  1977年   23篇
  1976年   17篇
  1974年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
PURPOSE: Hypoxia is associated with adverse outcome for a number of solid tumors, including cervical carcinomas. Direct pO(2) measurement requires specialized equipment and expertise that is not generally available. Immunohistochemical measurement of intrinsic tissue markers of hypoxia is an alternative approach. Recent studies suggest that carbonic anhydrase IX (CA IX), which is regulated via hypoxia-inducible factor 1, is a useful intrinsic marker of tumor hypoxia. EXPERIMENTAL DESIGN: Biopsies were obtained from 110 patients with locally advanced cervical carcinoma treated with radiotherapy or chemoradiotherapy. Tissue sections were labeled using an immunofluorescence technique and CA IX expression in the viable tumor area measured using a semiautomated fluorescence image analysis technique. Results were compared with direct pO(2) values obtained using an Eppendorf probe and to patient outcome. Intratumoral heterogeneity of CA IX expression was examined in a subgroup of patient who underwent multiple biopsies. RESULTS: The median percentage of tumor area staining for CA IX was 3.56 (range, 0.01-58.85). CA IX staining did not correlate with the Eppendorf pO(2) measurements. Whereas the latter values were predictive of patient outcome, the CA IX levels were not. Measurement of CA IX in multiple biopsies indicated that intratumoral heterogeneity accounted for 41% of the total variance in the data set. CONCLUSIONS: In contrast to some recent studies, we did not find significant associations between CA IX expression and tumor pO(2) levels or patient outcome in locally advanced carcinomas of the cervix. Probable explanations relate to the problems of sampling error using single biopsies and the existence of biological factors other than hypoxia that influence CA IX levels.  相似文献   
112.
The authors report a case of thrombosis of the spermatic veins associated with Henoch-Sch?nlein purpura mimicking an acute scrotum, which responded to a low-molecular-weight heparin treatment.  相似文献   
113.
The metabolic syndrome among postmenopausal women in Ecuador.   总被引:1,自引:0,他引:1  
BACKGROUND: The prevalence of the metabolic syndrome increases with age and after the onset of menopause, and may explain in part the apparent acceleration of cardiovascular disease in postmenopausal women. OBJECTIVE: To determine the prevalence of metabolic syndrome and related risk determinants among postmenopausal women in Ecuador. METHODS: Postmenopausal women >or=40 years of age, non-users of hormone therapy and with an intact uterus, were asked to participate in a metabolic syndrome screening and educational program at the Institute of Biomedicine of the Universidad Católica of Guayaquil, Ecuador. Sociodemographic data, waist circumference and blood pressure measurements were recorded, and a fasting blood sample obtained for serum glucose and lipid profile determinations. Woman were counseled and managed according to the results. Metabolic syndrome was defined in accordance with the criteria of the Third Adult Treatment Panel (ATP III). RESULTS: Three hundred and twenty-five postmenopausal women entered the program. Mean (+/-standard deviation) age was 55.9 +/- 8.1 years, 53.5% of them were aged >or=54 years (median). The prevalence of metabolic syndrome, according to ATP III criteria, was 41.5%. Using the same criteria, 38.8%, 16.6%, 56.9% and 54.2% of the women presented with hypertension, diabetes, hypertriglyceridemia and abdominal obesity, respectively. More than 40% of women determined to have hypertension or diabetes lacked knowing so. Logistic regression analysis determined that age increased the risk of presenting hypertension and diabetes (odds ratio (95% confidence interval): 2.0 (1.2-3.2) and 1.6 (0.9-3.0), respectively, p < 0.05), entities which in turn duplicated the risk of having high triglyceride levels. Sedentary women with <5 years since menopause onset were at higher risk of having abdominal obesity, which was directly related to diabetes and hypertension. CONCLUSIONS: In this postmenopausal Ecuadorian population the prevalence of the metabolic syndrome was high and its determinant factors related to age, time since menopause onset and sedentary habits. Because of the implications for cardiovascular risk, counseling programs directed toward high-risk populations should be encouraged.  相似文献   
114.
115.
PURPOSE: Gastrointestinal stromal tumors (GISTs) commonly harbor oncogenic mutations of the KIT tyrosine kinase, which is a target for the kinase inhibitor imatinib. A subset of GISTs, however, contains mutations in the homologous kinase platelet derived growth factor receptor alpha (PDGFRA), and the most common of these mutations is resistant to imatinib in vitro. Little is known of the other types of PDGFRA mutations that occur in GISTs. MATERIALS AND METHODS: We determined the KIT and PDGFRA mutation status of 1,105 unique GISTs using a combination of denaturing high-performance liquid chromatography and direct sequencing. RESULTS: 66 in exon 18, 11 in exon 12, and three in exon 14. Transient expression of representative PDGFRA isoforms in CHO cells revealed imatinib sensitivity of exon 12 mutations (SPDHE566-571R and insertion ER561-562) and an exon 14 substitution (N659K). However, most isoforms with a substitution involving codon D842 in exon 18 (D842V, RD841-842KI, DI842-843IM) were resistant to the drug, with the exception of D842Y. Interestingly, other mutations in exon 18 (D846Y, N848K, Y849K and HDSN845-848P) were all imatinib sensitive. Proliferation studies with BA/F3 cell lines stably expressing selected PDGFRA mutant isoforms supported these findings. CONCLUSION: Including our cases, there are 289 reported PDGFRA-mutant GISTs, of which 181 (62.6%) had the imatinib-resistant substitution D842V. However, our findings suggest that more than one third of GISTs with PDGFRA mutations may respond to imatinib and that mutation screening may be helpful in the management of these tumors.  相似文献   
116.
Recent reports have described neurobehavioral impairments in human subjects carrying a V66M polymorphism in the gene encoding brain-derived neurotrophic factor (BDNF). Inasmuch as ventral nervous system (CNS) deficits associated with this BDNF polymorphism are similar to those observed among subjects with chronic exposure to elemental mercury (Hg degrees ), we examined the potential effect of this BDNF polymorphism on symptoms and mood in an established cohort of dental practitioners with chronic low-level Hg degrees exposure. Self-reported symptoms and mood were obtained by computerized questionnaire from 193 male dentists (DTs) and 230 female dental assistants (DAs). Spot urine samples were analyzed for mercury concentrations to evaluate recent exposure. Detailed work histories were obtained to calculate chronic indices of Hg degrees exposure. Buccal cell samples were obtained to identify the V66M polymorphism of BDNF. Scores for 11 current and 12 recent and chronic symptom groups, along with six mood factors, were evaluated with respect to recent and chronic Hg degrees exposure and BDNF polymorphism. Multiple regression analysis controlled for age, race, socioeconomic status, tobacco and alcohol use, self-reported health problems, and medications. Separate evaluations were conducted for DTs and DAs. Twenty-three associations between recent or chronic Hg degrees exposure and BDNF status and self-reported symptoms were observed with p < 0.10. All but three were in the expected direction (symptom scores increasing with Hg degrees exposure or BDNF polymorphism), and all but six were among DAs. All eight correlations between chronic exposure indices and recent and chronic symptoms among DAs were in the expected direction. All seven associations between BDNF and symptoms were in the expected direction and split between DTs and DAs. All three associations with mood factors were among DAs and in the expected direction. These results indicate that among DAs very low levels of occupational Hg degrees exposure are associated with increased symptoms. The BDNF polymorphism is also associated with increased symptom and mood scores. Notably, Hg degrees and BDNF polymorphism were additive with respect to their associations with the same symptom group.  相似文献   
117.
118.
Patients with Beckwith‐Wiedemann spectrum (BWSp) undergo quarterly alpha‐fetoprotein measurement for hepatoblastoma (HB) screening up to 4 years of age, paralleling the epidemiology of nonsyndromic HB. However, specific data on the timing of HB development in BWSp are lacking. Here we compare the timing of presentation of HBs in BWSp with a control cohort of consecutive HB cases, demonstrating that halving screening duration of screening procedures in BWSp likely will not impact its effectiveness.  相似文献   
119.
Several randomized trials investigating the benefit of adjuvant chemotherapy after surgery in non-small cell lung cancer (NSCLC) have provided conflicting results. With over 7000 patients included, we analyzed results of 13 reports over the past 10 years in which patients received either platinum-containing chemotherapy or not. The major endpoint was to assess the magnitude of the benefit of adjuvant chemotherapy in terms of the absolute benefit. All phase III randomized trials and meta-analyses published as peer-reviewed papers or as abstracts from 1994 to 2007 were eligible. A literature-based meta-analysis was performed; event-based overall- and disease-free survival (OS/DFS) and Relative Risks (RRs) with 95% confidence intervals (CIs) were derived. Magnitudes of benefit were evaluated with: absolute benefit and the number of patients treated for one patient to benefit. Seven sub-populations were examined. Combined effect estimation was computed with fixed- and random-effect models; a heterogeneity test was also applied. Twelve trials plus an individual patient meta-analysis (7334 patients) were gathered; the trials were designed to determine if cisplatin- or carboplatin-based chemotherapy improves survival over surgery. When data were pooled and plotted, significant differences in favor of chemotherapy were seen in OS in all seven sub-population, with a relative benefit of 7-12% and an absolute benefit ranging from 2.5% to 4.1%. A more significant trend for chemotherapy was found in DFS. No significant heterogeneity was observed for all outcomes and sub-populations. The absolute benefit of adjuvant chemotherapy remains essentially the same regardless of how data are screened. While significant differences are clearly found in this analysis, the small magnitude of benefit seen with this large population, especially when considering the number of patients needed for one to benefit, raises important issues when weighing risks and benefits of treatment for individual patients.  相似文献   
120.
背部肌筋膜综合征主要是指因背部肌肉劳损、受凉引起,临床以背痛为主的一组征候群。只要诊断、定位明确,九一针疗法对此具有良好的疗效。  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