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   848篇
  免费   37篇
  国内免费   2篇
耳鼻咽喉   6篇
儿科学   34篇
妇产科学   27篇
基础医学   105篇
口腔科学   3篇
临床医学   54篇
内科学   210篇
皮肤病学   52篇
神经病学   50篇
特种医学   8篇
外科学   86篇
综合类   2篇
预防医学   34篇
眼科学   9篇
药学   70篇
肿瘤学   137篇
  2023年   3篇
  2021年   29篇
  2020年   11篇
  2019年   13篇
  2018年   16篇
  2017年   16篇
  2016年   13篇
  2015年   28篇
  2014年   32篇
  2013年   28篇
  2012年   65篇
  2011年   51篇
  2010年   31篇
  2009年   34篇
  2008年   49篇
  2007年   68篇
  2006年   62篇
  2005年   41篇
  2004年   41篇
  2003年   28篇
  2002年   27篇
  2001年   6篇
  2000年   3篇
  1999年   9篇
  1998年   4篇
  1995年   2篇
  1992年   3篇
  1991年   6篇
  1990年   5篇
  1989年   9篇
  1988年   6篇
  1987年   9篇
  1986年   5篇
  1984年   2篇
  1983年   3篇
  1979年   8篇
  1978年   6篇
  1977年   2篇
  1976年   4篇
  1975年   17篇
  1974年   10篇
  1973年   9篇
  1972年   10篇
  1971年   14篇
  1970年   8篇
  1969年   7篇
  1968年   5篇
  1967年   12篇
  1966年   4篇
  1965年   3篇
排序方式: 共有887条查询结果,搜索用时 62 毫秒
1.
Background The impact of various breast-cancer treatments on patients with a BRCA2 mutation has not been studied. We sought to estimate the impact of bilateral oophorectomy and other treatments on breast cancer-specific survival among patients with a germline BRCA2 mutation.Methods We identified 664 women with stage I–III breast cancer and a BRCA2 mutation by combining five different datasets (retrospective and prospective). Subjects were followed for 7.2 years from diagnosis to death from breast cancer. Tumour characteristics and cancer treatments were patient-reported and derived from medical records. Predictors of survival were determined using Cox proportional hazard models, adjusted for other treatments and for prognostic features.Results The 10-year breast-cancer survival for ER-positive patients was 78.9% and for ER-negative patients was 82.3% (adjusted HR = 1.23 (95% CI, 0.62–2.45, p = 0.55)). The 10-year breast-cancer survival for women who had a bilateral oophorectomy was 89.1% and for women who did not have an oophorectomy was 59.0% (adjusted HR = 0.45; 95% CI, 0.28–0.72, p = 0.001). The adjusted hazard ratio for chemotherapy was 0.83 (95% CI, 0.65–1.53: p = 0.56).Conclusions For women with breast cancer and a germline BRCA2 mutation, positive ER status does not predict superior survival. Oophorectomy is associated with a reduced risk of death from breast cancer and should be considered in the treatment plan.Subject terms: Targeted therapies, Breast cancer  相似文献   
2.
Combined liver-kidney transplantation (CLKT) is a rare procedure in pediatric patients in which liver and kidney from 1 donor are transplanted to a recipient during a single operation. The aim of our study was to analyze indications and results of CLKT in children.

Materials and Methods

Between 1990 and 2017 we performed 722 liver transplantations in children; we performed 920 kidney transplantations in children since 1984. Among them, 25 received CLKT. Primary diagnosis was fibro-polycystic liver and kidney disease in 17 patients, primary hyperoxaluria type 1 in 6 patients, and atypical hemolytic uremic syndrome-related renal failure in 2 children. Age of patients at CLKT was 3 to 23 years (median 16 years) and body mass was 11 to 55 kg (median 35.5kg). All patients received whole liver graft. Kidney graft was transplanted after liver reperfusion before biliary anastomosis. Cold ischemia time was 5.5 to 13.3 hours (median 9.4 hours) for liver transplants and 7.3 to 15 hours (median 10.4 hours) for kidney transplants. In 8 patients X-match was positive. We analyzed posttransplant (Tx) course and late results in our group of pediatric recipients of combined grafts.

Results

Tx follow-up ranged from 1.5 to 17 years (median 4.5 years). Two patients died: 1 patient with oxalosis lost renal graft and died 2.6 years after Tx due to complications of long-term dialysis, and 1 died due to massive bleeding in early postoperative period. Twelve patients were transferred under the care of adult transplantation centers. Six patients were dialyzed after CLKT due to acute tubular necrosis, and time of kidney function recovery was 10 to 27 days in these patients. In 1 patient with aHUS, renal function did not recover. In children with oxalosis, hemodialysis was performed for 1 month after Tx as a standard, with the aim to remove accumulated oxalate. Primary immunosuppression consisted of daclizumab or basiliximab, tacrolimus, mycophenolate mofetil, and steroids. Acute rejection occurred in 4 liver and 3 kidney grafts. One patient required liver retransplantation due to hepatitis C virus recurrence and 2 patients required kidney retransplantation. Two patients required dialysis.

Conclusions

CLKT in children results in low rate of rejection and high rate of patient and graft survival.  相似文献   
3.
We describe a case of a 36-year-old woman with severe hypertriglyceridemia likely caused by double heterozygosity of a known pathogenic APOA5 nonsense variant (p.Q275X) and a novel CREB3L3 nonsense variant (p.C296X) on a background of very strong polygenic susceptibility. Her clinical course worsened with development of eruptive xanthomata after oral administration of 2 mg estradiol twice daily for 2 weeks as part of a medical protocol for intrauterine embryo transfer following in vitro fertilization. Her triglyceride levels decreased to baseline and xanthomata resolved without treatment after discontinuation of hormonal therapy, which also resulted in termination of pregnancy. Before undergoing a second embryo transfer using her natural cycle and no exogenous hormones, the patient started combination therapy with eicosapentaenoic acid ethyl ester and gemfibrozil, leading to an ~80% decrease in triglyceride levels. She continued treatment throughout pregnancy, which progressed to term with the delivery of healthy twins.  相似文献   
4.
5.
The role of the lifetime number of ovulatory cycles has not been evaluated in the context of BRCA‐associated ovarian cancer. Thus, we conducted a matched case–control study to evaluate the relationship between the cumulative number of ovulatory cycles (and contributing components) and risk of developing ovarian cancer in BRCA mutation carriers (1,329 cases and 5,267 controls). Information regarding reproductive and hormonal factors was collected from a routinely administered questionnaire. Conditional logistic regression was used to evaluate all associations. We observed a 45% reduction in the risk of developing ovarian cancer among women in the lowest vs. highest quartile of ovulatory cycles (OR = 0.55; 95% CI 0.41–0.75, p = 0.0001). Breastfeeding for more than 12 months was associated with a 38% (95% CI 0.48–0.79) and 50% (95% CI 0.29–0.84) reduction in risk among BRCA1 and BRCA2 mutation carriers, respectively. For oral contraceptive use, maximum benefit was seen with five or more years of use among BRCA1 mutation carriers (OR = 0.50; 95% CI 0.40–0.63) and three or more years for BRCA2 mutation carriers (OR = 0.42; 95% CI 0.22–0.83). Increasing parity was associated with a significant inverse trend among BRCA1 (OR = 0.87; 95% CI 0.79–0.96; p‐trend = 0.005) but not BRCA2 mutation carriers (OR 0.98; 95% CI 0.81–1.19; p‐trend = 0.85). A later age at menopause was associated with an increased risk in women with a BRCA1 mutation (OR trend = 1.18; 95% CI 1.03–1.35; p = 0.02). These findings support an important role of breastfeeding and oral contraceptive use for the primary prevention of ovarian cancer among women carrying BRCA mutations.  相似文献   
6.
Mutations in the cell cycle checkpoint kinase 2 (CHEK2) tumor suppressor gene are associated with multi‐organ cancer susceptibility including cancers of the breast and prostate. A genetic association between thyroid and breast cancer has been suggested, however little is known about the determinants of this association. To characterize the association of CHEK2 mutations with thyroid cancer, we genotyped 468 unselected patients with papillary thyroid cancer and 468 (matched) cancer‐free controls for four founder mutations of CHEK2 (1100delC, IVS2 + 1G>A, del5395 and I157T). We compared the family histories reported by patients with a CHEK2 mutation to those of non‐carriers. A CHEK2 mutation was seen in 73 of 468 (15.6%) unselected patients with papillary thyroid cancer, compared to 28 of 460 (6.0%) age‐ and sex‐matched controls (OR 3.3; p < 0.0001). A truncating mutation (IVS2 + 1G>A, 1100delC or del5395) was associated with a higher risk of thyroid cancer (OR = 5.7; p = 0.006), than was the missense mutation I157T (OR = 2.8; p = 0.0001). CHEK2 mutation carriers reported a family history of breast cancer 2.2 times more commonly than non‐carriers (16.4% vs.8.1%; p = 0.05). A CHEK2 mutation was found in seven of 11 women (63%) with multiple primary cancers of the breast and thyroid (OR = 10; p = 0.0004). These results suggest that CHEK2 mutations predispose to thyroid cancer, familial aggregations of breast and thyroid cancer and to double primary cancers of the breast and thyroid.  相似文献   
7.
8.
A growing body of evidence indicates that miRNAs may be a class of genetic elements that can either drive or suppress oncogenesis. In this study we analyzed the somatic copy number variation of 14 miRNA genes frequently found to be either over- or underexpressed in lung cancer, as well as two miRNA biogenesis genes, DICER1 and DROSHA, in non-small-cell lung cancer (NSCLC). Our analysis showed that most analyzed miRNA genes undergo substantial copy number alteration in lung cancer. The most frequently amplified miRNA genes include the following: miR-30d, miR-21, miR-17 and miR-155. We also showed that both DICER1 and DROSHA are frequently amplified in NSCLC. The copy number variation of DICER1 and DROSHA correlates well with their expression and survival of NSCLC and other cancer patients. The increased expression of DROSHA and DICER1 decreases and increases the survival, respectively. In conclusion, our results show that copy number variation may be an important mechanism of upregulation/downregulation of miRNAs in cancer and suggest an oncogenic role for DROSHA.  相似文献   
9.
This study examined the significance of selected parameters of primary haemostasis to discriminate between relatives of children with insulin-dependent diabetes mellitus (IDDM). Platelet function, including markers of spontaneous and agonist-induced platelet activation (CD62), platelet consumption (microparticles) and clumping (aggregates), as well as selected parameters of the fibrinolytic system (t-PA and PAI-1), were studied in IDDM children (n = 45), their parents (n = 65), siblings (n = 17) and unrelated healthy controls (n = 51). The fraction of activated platelets circulating in whole blood amounted to 4.3±2.1% in IDDM children, and significantly exceeded the level found in parents (1.3±0.7%, P < 0.002), siblings (1.2±1.0%, P < 0.002), and controls (1.2±0.6%, P < 0.002). Furthermore, an enhanced formation of platelet microparticles was observed in the IDDM group, both in resting platelets and also when platelets were stimulated with thrombin. Significantly decreased total PAI-1 occurred in IDDM children (P < 0.02 versus parents); also slightly lowered active PAI-1 and t-PA antigen were noticed in IDDM subjects compared to other groups, however, the differences were not statistically significant. To assess dissimilarities between the groups of subjects we applied the forward stepwise model of discriminant function analysis, which included platelet flow cytometry parameters. The best separation and the highest discrepancy (expressed as the so called squared Mahalanobis distances, dM) was revealed between controls and IDDM patients (P ? 0.0001) and between controls and parents (P ? 0.0001). The values of dM found between IDDM children and their siblings (P < 0.001), as well as parents (P < 0.01), were of much lower significance. The finding that the control group, representing unrelated subjects, remains particularly well separated from the other groups, more or less clustered together, implies the possible involvement of genetic factor(s) which might potentially affect platelet activation and reactivity. In addition, the distinguished distribution of HLA DQAI52 and HLA DQBI57 genotypes in the groups further validates the suspicion that the altered platelet function and response in diabetes might be associated with some independent genetic factor(s), and is not likely to result from HLA DQAI52 and HLA DQBI57 impact.  相似文献   
10.
The detonation gun sprayed Fe-Al type coatings as an alternative for austenitic valve steel, were investigated using two different methods of testing corrosion resistance. High temperature, 10-hour isothermal oxidation experiments at 550, 750, 950 and 1100 °C show differences in the oxidation behavior of Fe-Al type coatings under air atmosphere. The oxide layer ensures satisfying oxidation resistance, even at 950 and 1100 °C. Hematite, α-Al2O3 and metastable alumina phases were noticed on the coatings top surface, which preserves its initial thickness providing protection to the underlying substrate. In general, only negligible changes of the phase composition of the coatings were noticed with simultaneous strengthening controlled in the micro-hardness measurements, even after 10-hours of heating at 1100 °C. On the other hand, the electrochemical corrosion tests, which were carried out in 200 ppm Cl (NaCl) and pH ~4 (H2SO4) solution to simulate the acid-rain environment, reveal higher values of the breakdown potential for D-gun sprayed Fe-Al type coatings than the ones for the bulk Fe-Al type alloy and Cr21Mn9Ni4 austenitic valve steel. This enables these materials to be used in structural and multifunctional applications in aggressive environments, including acidic ones.  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