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   1345篇
  免费   66篇
  国内免费   6篇
耳鼻咽喉   6篇
儿科学   43篇
妇产科学   63篇
基础医学   168篇
口腔科学   12篇
临床医学   108篇
内科学   356篇
皮肤病学   13篇
神经病学   148篇
特种医学   35篇
外科学   78篇
综合类   8篇
一般理论   1篇
预防医学   59篇
眼科学   28篇
药学   103篇
中国医学   13篇
肿瘤学   175篇
  2024年   4篇
  2023年   10篇
  2022年   20篇
  2021年   44篇
  2020年   29篇
  2019年   30篇
  2018年   34篇
  2017年   32篇
  2016年   28篇
  2015年   32篇
  2014年   53篇
  2013年   61篇
  2012年   86篇
  2011年   98篇
  2010年   47篇
  2009年   54篇
  2008年   81篇
  2007年   85篇
  2006年   94篇
  2005年   97篇
  2004年   98篇
  2003年   83篇
  2002年   62篇
  2001年   15篇
  2000年   13篇
  1999年   12篇
  1998年   13篇
  1997年   7篇
  1996年   7篇
  1995年   9篇
  1994年   9篇
  1993年   5篇
  1992年   8篇
  1991年   6篇
  1990年   5篇
  1989年   6篇
  1988年   8篇
  1987年   4篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1983年   1篇
  1982年   2篇
  1981年   3篇
  1980年   1篇
  1979年   3篇
  1977年   1篇
  1975年   3篇
  1968年   2篇
  1962年   1篇
排序方式: 共有1417条查询结果,搜索用时 15 毫秒
11.
Recent studies in mouse models of cancer have shown that exercise improves tumor vascular function, thereby improving chemotherapy delivery and efficacy. However, the mechanisms underlying this improvement remain unclear and the effect of exercise on Ewing sarcoma (ES), a pediatric bone and soft tissue cancer, is unknown. The effect of exercise on tumor vascular hyperpermeability, which inversely correlates with drug delivery to the tumor, has also not been evaluated. We hypothesized that exercise improves chemotherapy efficacy by enhancing its delivery through improving tumor vascular permeability. We treated ES‐bearing mice with doxorubicin with or without moderate treadmill exercise. Exercise did not significantly alter ES tumor vessel morphology. However, compared to control mice, tumors of exercised mice had significantly reduced hyperpermeability, significantly decreased hypoxia, and higher doxorubicin penetration. Compared to doxorubicin alone, doxorubicin plus exercise inhibited tumor growth more efficiently. We evaluated endothelial cell sphingosine‐1‐phosphate receptors 1 and 2 (S1PR1 and S1PR2) as potential mediators of the improved vascular permeability and increased function afforded by exercise. Relative to tumors from control mice, vessels in tumors from exercised mice had increased S1PR1 and decreased S1PR2 expression. Our results support a model in which exercise remodels ES vasculature to reduce vessel hyperpermeability, potentially via modulation of S1PR1 and S1PR2, thereby improving doxorubicin delivery and inhibiting tumor growth more than doxorubicin alone does. Our data suggest moderate aerobic exercise should be tested in clinical trials as a potentially useful adjuvant to standard chemotherapy for patients with ES.  相似文献   
12.
13.
ObjectiveThe aim of the study was to investigate the potential clinical relevance of immunohistochemically assessed RON expression in a large, single institution series of primary untreated advanced ovarian cancer patients.MethodsImmunohistochemical analysis was performed by using the polyclonal rabbit anti-RON-β antibody (C-20, clone sc-322, Santa Cruz, California). Results were expressed as the total proportion of immunostained tumor cells (RON positivity), or the percentage of cells showing strong staining of RON expression (H-RON positivity).ResultsIn the overall series RON positive immunoreaction was observed in 103/141 cases, while H-Ron positivity was detected in 577141 (40.4%) cases. No association between RON and H-RON expression with response to first-line treatment was documented. During the follow up period, progression and death of disease were observed in 111 (78.7%) and 76 (53.9%) cases, respectively. Cases with strong H-RON expression has a shorter overall survival (median = 35 months) than cases with low RON levels (median = 59 months) (X2 = ? 2.1, p value = 0.032). In multivariate analysis, only platinum resistance, and extent of residual tumor retained an independent negative prognostic role for OS, with the percentages of H-RON positively immunostained cells showing a borderline statistical significance (p value = 0.0643). The unfavourable role of elevated percentages of H-RON expression was maintained only in the subgroup of platinum resistant recurrent ovarian cancer patients (X2 = 3.89, p value = 0.048) compared to the platinum sensitive ones (X2 = 1.98, p value = 0.16).ConclusionsThe assessment of RON expression deserves further attention as a parameter helpful to identify poor prognosis ovarian cancer patients potentially candidates to investigational agents.  相似文献   
14.
Objective To assess the accuracy of vaginal fetal fibronectin (FFN) as a screening test for preterm delivery in a community hospital. Study design A prospective cohort of patients at high risk for preterm delivery at a community hospital underwent testing with FFN over a 15 month-period (March 2004–May 2005). Indications for testing were preterm labor, multiple pregnancies, cervical shortening, and cerclage. Pregnancy characteristics were retrieved on all women with positive FFN results and controls in a 1:2 ratio. Outcome variables included interval to delivery; length of hospital stay; and rates of preterm delivery <37 weeks. In the presence of serial FFN testing, only the initial result was used for calculation of diagnostic indices. Statistical analysis utilized t-test, Fisher’s exact test and logistic regression analyis to control for gestational age at testing, with P < 0.05 or odds ratio (OR) with 95% confidence interval (CI) not inclusive of the unity considered significant. Results Two hundred and fifty seven FFN tests were performed in 230 women, of which 33 (14.3%) had positive FFN results. Duration of hospital stay was significantly shorter for patients with negative than positive results (8 h vs. 2.1 days, P = 0.011). Women with positive FFN were more likely to deliver within 14 days (OR = 6.5, 95% CI 1.4; 30.7), within 21 days (OR = 4.8; 95% CI 1.4; 16.6), before 34 weeks (OR = 5.0, 95% CI 1.7; 14.8) and before 37 weeks (OR = 3.1; 95% CI 1.3; 7.1) than women with negative results. Conclusion A negative FFN result provides enough reassurance to allow shorter hospital stay. In a real-world setting (a community hospital with a population heterogenous for risk factors for preterm delivery, and in a non-protocol setting) the performance of FFN testing closely mirrors that obtained in academic institutions, where the test was studied in more uniform populations under strict protocols. Summary The performance of vaginal fibronectin in patients with heterogeneous risk factors for preterm delivery closely mirrors that obtained in studies conducted in populations with homogeneous risk factors.  相似文献   
15.
BackgroundDiffuse midline gliomas (DMG) H3K27M-mutant, including diffuse intrinsic pontine glioma (DIPG), are pediatric brain tumors associated with grim prognosis. Although GD2-CAR T-cells demonstrated significant anti-tumor activity against DMG H3K27M-mutant in vivo, a multimodal approach may be needed to more effectively treat patients. We investigated GD2 expression in DMG/DIPG and other pediatric high-grade gliomas (pHGG) and sought to identify chemical compounds that would enhance GD2-CAR T-cell anti-tumor efficacy.MethodsImmunohistochemistry in tumor tissue samples and immunofluorescence in primary patient-derived cell lines were performed to study GD2 expression. We developed a high-throughput cell-based assay to screen 42 kinase inhibitors in combination with GD2-CAR T-cells. Cell viability, western blots, flow-cytometry, real time PCR experiments, DIPG 3D culture models, and orthotopic xenograft model were applied to investigate the effect of selected compounds on DIPG cell death and CAR T-cell function.ResultsGD2 was heterogeneously, but widely, expressed in the tissue tested, while its expression was homogeneous and restricted to DMG/DIPG H3K27M-mutant cell lines. We identified dual IGF1R/IR antagonists, BMS-754807 and linsitinib, able to inhibit tumor cell viability at concentrations that do not affect CAR T-cells. Linsitinib, but not BMS-754807, decreases activation/exhaustion of GD2-CAR T-cells and increases their central memory profile. The enhanced anti-tumor activity of linsitinib/GD2-CAR T-cell combination was confirmed in DIPG models in vitro, ex vivo, and in vivo.ConclusionOur study supports the development of IGF1R/IR inhibitors to be used in combination with GD2-CAR T-cells for treating patients affected by DMG/DIPG and, potentially, by pHGG.  相似文献   
16.
Background and Objectives Medullary thyroid carcinoma (MTC) is a calcitonin (CT)‐secreting neuroendocrine tumour originating from thyroid C cells. Serum CT concentrations are helpful in the early detection of MTC, while it is still unclear whether they can be used also for the differential diagnosis between MTC and C‐cell hyperplasia (CCH), a precancerous condition in familial MTCs but with unclear clinical significance in sporadic MTCs. Nowadays, surgery is recommended in all patients with basal or pentagastrin (PG)‐stimulated CT value of 100 pg/ml or more, without discriminating if they are affected with MTC or CCH only. The objective of this study was to investigate the utility of the PG test for CT in distinguishing CCH from MTC before surgery. Patients and Methods Sixteen of 20 patients with thyroid nodules and basal CT levels between 15 and 100 ng/l had a positive PG test (>100 ng/l PG CT peak) and form the basis of the data analysis. A diagnosis of MTC was histologically proved on surgical samples in seven patients and of CCH in nine other patients. Four patients with neither FNAB nor PG test consistent with a diagnosis of MTC did not undergo thyroidectomy. Results A peak of CT of 275 ng/l after PG was able to significantly distinguish patients with MTC from patients with CCH, with 100% sensitivity and 89% specificity (P = 0·002). PG‐stimulated calcitonin levels >275 ng/l had a positive predictive value (PPV) value for diagnosis of MTC of 100%, and PG‐stimulated calcitonin levels <275 had a PPV for the diagnosis of CCH of 89%. Conclusions A CT cut‐off after PG of 275 ng/l is suggested to be highly predictive in distinguishing CCH from MTC before surgery, and this may be helpful in selecting patients for thyroid surgery.  相似文献   
17.
Diagnostic reliability of indexations of peak exercise ST segment depression (DeltaST) for heart rate reserve (HRi) or chronotropic reserve (CR) to identify significant coronary artery disease (CAD) by cycle-ergometer exercise testing has not been evaluated previously. Exercise testing by upright cycle-ergometer (25 W/3 min) were performed in consecutive patients in primary prevention with history of exercise-related chest discomfort and cardiovascular risk factors, or with overt peripheral artery disease, with or type-2 diabetes associated with two or more additional cardiovascular risk factors. Coronary angiography was performed after the test to assess significant CAD. Three different criteria for definition of inducible myocardial ischemia were tested versus significant CAD: peak DeltaST>or=100 microV, ST/HRi>1.69 microV/bpm or ST/CR>1.76 microV/%. Diagnostic accuracy vs. CAD of DeltaST>or=100 microV, of ST/HRi>1.69 microV/bpm, and of ST/CR>1.76 microV/% were 78%, 72%, and 89% respectively; sensitivity and specificity of the three criteria were 91% and 50%, 84% and 43%, 88% and 93%, respectively. Abnormal ST/CR predicted CAD independent of risk factors, pre-test probability, and more strongly than DeltaST. Combination of ST/HRi and ST/CR criteria did not improve CAD prediction. In conclusions, in clinical setting in patients in primary prevention but with moderate-to-high pre-test probability of CAD, exercise testing by cycle-ergometry and use of ST/CR>1.76 microV/% showed elevated sensitivity and specificity, and the best accuracy for diagnosis of significant CAD.  相似文献   
18.
BACKGROUND: Little is known about the morphological and functional evolution of ventricular abnormalities in Loeffler endocarditis. METHODS AND RESULTS: We describe 5 patients, including 3 with long-term echocardiographic follow-up, in whom apical obliteration due to fibro-thrombotic thickening of the endocardium showed favorable patterns of evolution. In one patient there was almost complete resolution of the obliterative process with consequently increased effective ventricular volume. In two patients formation of a flow-passage in the fibrocalcific apical 'floor' between the main medioventricular cavity and the apical chamber, leading to a 'double-chambered' left ventricle was observed. CONCLUSIONS: Medical therapy and appropriate anticoagulation, can induce favorable long-term ventricular remodeling in Loeffler endocarditis.  相似文献   
19.
The study investigated whether the cardiac activity and cognitive–emotional traits sustained by the behavioral inhibition/activation system (BIS/BAS) may contribute to hypnotizability-related pain modulation. Nociceptive stimulation (cold-pressor test) was administered to healthy participants with high (highs) and low (lows) hypnotizability in the presence and absence of suggestions for analgesia. Results showed that heart rate increased abruptly at the beginning of nociceptive stimulation in all participants. Then, only in highs heart rate decreased for the entire duration of hand immersion. During stimulation with suggestions of analgesia, pain threshold negatively correlated with heart rate. BIS/BAS activity partially accounted for the observed hypnotizability-related differences in the relation between cardiac interoception and pain experience.  相似文献   
20.

Purpose:

To report our clinical experience and 4-year follow-up results of Descemet stripping automated endothelial keratoplasty (DSAEK) with the suture pull-through insertion technique.

Methods:

This is a retrospective study of 195 eyes in which a posterior lamellar keratoplasty was performed between 2007 and 2011. The insertion of a folded donor lenticule was performed with a double-armed 10-0 suture using a straight transchamber needle and half-circle needle. Endothelial cell density was measured annually up to 4 years after the surgery, and cell loss was calculated based on the median preoperative donor endothelial cell density. Postoperative complications, primary graft failure, pupillary block, and dislocation of the donor tissue were assessed.

Results:

All patients underwent uncomplicated DSAEK. Data were available for 195 eyes (100%) at 1 year, 186 eyes (95.3%) at 2 years, 176 eyes (90.2%) at 3 years, and 160 eyes (82%) at 4 years. Median preop-erative donor endothelial cell density was 2688 cells/mm2 [interquartile range (IQR) 207.5 cells/mm2], which decreased by 27% at 1 year (1956 cells/mm2, IQR 264.8 cells/mm2), 31% at 2 years (1855 cells/mm2, IQR 320.5 cells/mm2), 35% at 3 years (1756.5 cells/mm2, IQR 306.5 cells/mm2), and 36% at 4 years (1709.5 cells/mm2, IQR 288,0 cells/mm2). Nine patients (4.6%) had a dislocation of donor tissue; all were successfully reattached with a second air injection. Only three eyes (1.5%) developed graft failure. Pupillary block was present in 15 eyes (7.7%).

Conclusion:

DSAEK with suture pull-through insertion of donor graft represents a simplified and safe technique that has endothelial cell loss comparable with other techniques and low rates of intraoperative and postoperative complications.  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