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   2561篇
  免费   226篇
  国内免费   9篇
耳鼻咽喉   1篇
儿科学   84篇
妇产科学   99篇
基础医学   321篇
口腔科学   11篇
临床医学   461篇
内科学   457篇
皮肤病学   47篇
神经病学   193篇
特种医学   17篇
外科学   281篇
综合类   58篇
预防医学   388篇
眼科学   28篇
药学   158篇
中国医学   1篇
肿瘤学   191篇
  2024年   3篇
  2023年   17篇
  2022年   11篇
  2021年   37篇
  2020年   15篇
  2019年   41篇
  2018年   58篇
  2017年   58篇
  2016年   54篇
  2015年   68篇
  2014年   91篇
  2013年   109篇
  2012年   169篇
  2011年   187篇
  2010年   108篇
  2009年   102篇
  2008年   199篇
  2007年   185篇
  2006年   185篇
  2005年   197篇
  2004年   208篇
  2003年   186篇
  2002年   164篇
  2001年   37篇
  2000年   28篇
  1999年   26篇
  1998年   35篇
  1997年   34篇
  1996年   25篇
  1995年   19篇
  1994年   11篇
  1993年   13篇
  1992年   6篇
  1991年   9篇
  1990年   8篇
  1989年   7篇
  1988年   5篇
  1986年   8篇
  1985年   8篇
  1984年   8篇
  1983年   9篇
  1982年   10篇
  1981年   7篇
  1980年   8篇
  1979年   5篇
  1978年   4篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1972年   2篇
排序方式: 共有2796条查询结果,搜索用时 13 毫秒
81.
Primarily saprophytic in nature, fungi of the genus Acremonium are a well-documented cause of mycetoma and other focal diseases. More recently, a number of Acremonium spp. have been implicated in invasive infections in the setting of severe immunosuppression. During the course of routine microbiological studies involving a case of fatal mycosis in a nonmyeloablative hematopoietic stem cell transplant patient, we identified a greater-than-expected variation among strains previously identified as Acremonium strictum by clinical microbiologists. Using DNA sequence analysis of the ribosomal DNA intergenic transcribed spacer (ITS) regions and the D1-D2 variable domain of the 28S ribosomal DNA gene (28S), the case isolate and four other clinical isolates phenotypically identified as A. strictum were found to have <99% homology to the A. strictum type strain, CBS 346.70, at the ITS and 28S loci, while a sixth isolate phenotypically identified only as Acremonium sp. had >99% homology to the type strain at both loci. These results suggest that five out of the six clinical isolates belong to species other than A. strictum or that the A. strictum taxon is genetically diverse. Based upon these sequence data, the clinical isolates were placed into three genogroups.  相似文献   
82.
Posttraumatic stress symptoms in parents of children with acute burns   总被引:2,自引:0,他引:2  
OBJECTIVE: To develop a model of risk factors for posttraumatic stress disorder (PTSD) symptoms in parents of children with burns. METHODS: Immediately following the burn and 3 months later, parents reported on their children's and their own psychological functioning and traumatic stress responses. RESULTS: Approximately 47% of the parents reported experiencing significant posttraumatic stress symptoms 3 months after the burn. Our model indicates three independent pathways to PTSD symptoms (i.e., parent-child conflict, parents' dissociation, and children's PTSD symptoms). Additionally, parents' anxiety predicted increased parent-child conflict, conflict with extended family and size of the burn predicted parents' dissociation, and size of the burn and children's dissociation predicted children's PTSD symptoms. CONCLUSIONS: This study suggests that many parents of children with burns suffer from posttraumatic stress symptoms. Interventions that target factors such as family conflict, children's symptoms, and parents' acute anxiety and dissociation may diminish the risk for PTSD.  相似文献   
83.
We have examined gene expression in multipotent neural precursor cells (NPCs) derived from human fetal (f) brain tissue and compared its expression profiles with embryonic stem (ESC) cells, embryoid body cell (EBC), and astrocyte precursors using the technique of massively parallel signature sequencing (MPSS). Gene expression profiles show that fNPCs express core neural stem cells markers and share expression profiles with astrocyte precursor cells (APCs) rather than ESC or EBC. Gene expression analysis shows that fNPCs differ from other adult stem and progenitor cells in their marker expression and activation of specific functional networks such as the transforming growth factorbeta (TGFbeta) and Notch signaling pathways. In addition, our results allow us to identify novel genes expressed in fNPCs and provide a detailed profile of fNPCs.  相似文献   
84.

Objective

Recent studies have demonstrated that lymphovascular space invasion (LVSI) is associated with increased risk of hematogenous and lymphatic metastasis and poor clinical outcome of women with epithelial ovarian cancer. Given the suspected role of estrogen in promoting ovarian cancer metastasis, we examined potential links between estrogen receptor and LVSI in high-grade serous ovarian carcinoma.

Methods

Tumoral expression of ER, PR, p53, MDR1, EGFR, HER2, DNA ploidy, and S-phase fraction was examined for 121 cases of stage I–IV high-grade serous ovarian carcinoma samples obtained at primary cytoreductive surgery. Biomarker expression was correlated to LVSI and survival outcomes.

Results

LVSI was observed in 101 (83.5%) of all cases. Immunohistochemistry of tested biomarkers showed ER (86.7%) to be the most commonly expressed followed by p53 (71.4%), HER2 (68.3%), EGFR (52.1%), MDR-1 (14.3%), and PR (8.9%). ER expression was positively correlated to PR expression (r = 0.31, p = 0.001). LVSI was only correlated with ER (odds ratio 6.27, 95%CI 1.93–20.4, p = 0.002) but not with other biomarkers. In multivariate analysis, ER remained significantly associated with LVSI (p = 0.039). LVSI remained a significant prognostic factor for decreased progression-free survival (HR 3.01, 95%CI 1.54–5.88, p = 0.001) and overall survival (HR 2.69, 95%CI 1.18–6.23, p = 0.021) while ER-expression did not remain as a significant variable in multivariate analysis.

Conclusion

Our data demonstrated that estrogen receptor was positively correlated with LVSI that was an independent prognostic indicator of poor survival outcomes of high-grade serous ovarian carcinoma. This study emphasizes the importance of estrogen pathway in promoting lymphatic or vascular spread of high-grade serous ovarian carcinoma.  相似文献   
85.
86.
We examined the hypothesis that mitral valve prolapse is often associated with an inherited, anthropometrically distinct habitus. Using standard echo- and phonocardiographic techniques, we identified 60 subjects with mitral valve prolapse, 21 first-degree relatives (12 with mitral valve prolapse and nine normal) and a control group of 57 normal women. Patients with “silent” (echo only) mitral valve prolapse or the Marfan syndrome were excluded. Analysis of measurements taken of the first 39 patients and 46 control subjects revealed that, in relation to their height, patients with mitral valve prolapse had narrower anteroposterior chest diameters and longer arm spans than did the women in the control group. Linear discriminant analysis produced the equation: Z = 17.511 + 98.6 (anteroposterior chest diameter/height) ? 27.3 (arm span/height). Those with mitral valve prolapse tended to score below zero (mean, ?0.62), whereas normal subjects tended to score above zero (mean, 0.39; p < 0.001). The equation was tested prospectively on 53 subjects, including the 21 family members, and correctly classified 75 percent of all unrelated subjects and 86 percent of the family members as normal or having mitral valve prolapse. Both mitral valve prolapse and discriminant classification followed an autosomally dominant pattern of inheritance. We conclude that a significant proportion of patients with mitral valve prolapse have an autosomally dominant, inherited, anthropometrically distinct habitus, suggesting that mitral valve prolapse is only one component of a generalized developmental syndrome.  相似文献   
87.
Although women have a lower risk of stroke during middle age than men, the menopausal transition is a time when many women develop cardiovascular risk factors. Additionally, during the 10 years after menopause, the risk of stroke roughly doubles in women. Endogenous oestrogen concentrations decline by 60% during the menopausal transition, leading to a relative androgen excess, which could contribute to the increased cardiovascular risk factors in women. Earlier onset of menopause might affect the risk of stroke, but the data are not clear. Because of the stroke risk associated with it, hormone therapy is recommended only for treatment of vasomotor symptoms, and some formulations might be safer than others. More research is needed to understand which women are at greatest stroke risk during midlife and to identify the safest formulation, dose, and duration of hormone therapy that can be used to treat vasomotor symptoms without increasing the risk of stroke.  相似文献   
88.
OBJECTIVES: To assess the safety and tolerability of a topical gel formulation combining methotrexate and laurocapram and to obtain preliminary information on the therapeutic potential of methotrexate-laurocapram in patients with early-stage mycosis fungoides (stage IA or IB). DESIGN: An open-label, phase 1/2 pilot study. SETTING: Two academic referral centers. PATIENTS: Ten patients 18 years or older with histologically confirmed stage IA or IB mycosis fungoides.Intervention The gel formulation of methotrexate-laurocapram was applied to the total body surface, excluding genital, perianal areas, nipples, face, and skin under the breasts, on an every-other-day basis for 24 consecutive weeks. MAIN OUTCOME MEASURES: The safety of methotrexate-laurocapram was assessed in this study by reviewing adverse events and laboratory data. Efficacy outcomes included changes in lesion condition and severity assessments, reduction in area of sample lesions, and the investigator's global evaluation. RESULTS: Adverse events consisted of skin reactions of mild severity. No clinically significant laboratory abnormalities were observed. Based on the investigator's global evaluation at the end of the treatment phase (week 24), 7 (78%) of 9 patients demonstrated a slight-to-moderate response to treatment with methotrexate-laurocapram. Statistical significance (P =.049) was reached for induration and pruritus, a trend (P =.10) was observed for erythema, and no change was found for scaling (P =.37). CONCLUSIONS: These findings indicate that the topical administration of methotrexate-laurocapram is safe and in general well tolerated. This treatment may represent a new therapeutic potential for patients with mycosis fungoides.  相似文献   
89.
90.
Background: The authors tested the hypotheses that protein kinase C (PKC)-specific isoform translocation and Src protein tyrosine kinase (PTK) activation play important roles in isoflurane-induced preconditioning in vivo.

Methods: Rats (n = 125) instrumented for measurement of hemodynamics underwent 30 min of coronary artery occlusion followed by 2 h of reperfusion and received 0.9% saline (control); PKC inhibitors chelerythrine (5 mg/kg), rottlerin (0.3 mg/kg), or PKC-[epsilon]V1-2 peptide (1 mg/kg); PTK inhibitors lavendustin A (1 mg/kg) or 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP1; 1 mg/kg); mitochondrial adenosine triphosphate-sensitive potassium channel antagonist 5-hydroxydecanote (10 mg/kg); or reactive oxygen species scavenger N-acetylcysteine (150 mg/kg) in the absence and presence of a 30-min exposure to isoflurane (1.0 minimum alveolar concentration) in separate groups. Isoflurane was discontinued 15 min before coronary occlusion (memory period). Infarct size was determined using triphenyltetrazolium staining. Immunohistochemistry and confocal microscopic imaging were performed to examine PKC translocation in separate groups of rats.

Results: Isoflurane significantly (P < 0.05) reduced infarct size (40 +/- 3% [n = 13]) as compared with control experiments (58 +/- 2% [n = 12]). Chelerythrine, rottlerin, PKC-[epsilon]V1-2 peptide, lavendustin A, PP1, 5-hydroxydecanote, and N-acetylcysteine abolished the anti-ischemic actions of isoflurane (58 +/- 2% [n = 8], 50 +/- 3% [n = 9], 53 +/- 2% [n = 9], 59 +/- 3% [n = 6], 57 +/- 3% [n = 7], 60 +/- 3% [n = 7], and 53 +/- 3% [n = 6], respectively). Isoflurane stimulated translocation of the [delta] and [epsilon] isoforms of PKC to sarcolemmal and mitochondrial membranes, respectively.  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