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   3692篇
  免费   223篇
  国内免费   44篇
耳鼻咽喉   50篇
儿科学   123篇
妇产科学   137篇
基础医学   407篇
口腔科学   59篇
临床医学   276篇
内科学   716篇
皮肤病学   97篇
神经病学   247篇
特种医学   178篇
外科学   613篇
综合类   179篇
预防医学   192篇
眼科学   101篇
药学   368篇
中国医学   33篇
肿瘤学   183篇
  2023年   28篇
  2022年   83篇
  2021年   123篇
  2020年   55篇
  2019年   94篇
  2018年   119篇
  2017年   84篇
  2016年   80篇
  2015年   85篇
  2014年   145篇
  2013年   156篇
  2012年   213篇
  2011年   241篇
  2010年   155篇
  2009年   119篇
  2008年   192篇
  2007年   214篇
  2006年   175篇
  2005年   180篇
  2004年   121篇
  2003年   132篇
  2002年   101篇
  2001年   57篇
  2000年   62篇
  1999年   72篇
  1998年   51篇
  1997年   36篇
  1996年   51篇
  1995年   25篇
  1994年   37篇
  1993年   18篇
  1992年   45篇
  1991年   49篇
  1990年   57篇
  1989年   43篇
  1988年   42篇
  1987年   28篇
  1986年   33篇
  1985年   37篇
  1984年   19篇
  1983年   16篇
  1981年   21篇
  1980年   17篇
  1979年   26篇
  1978年   17篇
  1976年   31篇
  1975年   17篇
  1974年   24篇
  1973年   18篇
  1971年   15篇
排序方式: 共有3959条查询结果,搜索用时 15 毫秒
71.
Background The clinical characteristics of vitiligo in children and adolescents with an emphasis on thyroid dysfunction have only been reported in a few studies. Objective The purpose of this study was to examine the characteristics of children and adolescents with vitiligo and compare the incidence of thyroid dysfunction between them and controls without vitiligo at the same age. Methods A retrospective analysis of 324 Korean children and adolescents with vitiligo was performed. The results of thyroid function screening tests in them (n = 254) were compared with controls (n = 122). Results Of the total 324 children and adolescents with vitiligo, vitiligo vulgaris was the most common type (42.3%) and the most commonly involved site was the face (54.6%). A total of 15 of 254 (5.9%) patients screened for thyroid function were diagnosed with thyroid disease (four had Hashimoto’s thyroiditis; two, Graves’ disease; seven, subclinical hypothyroidism; and two, subclinical hyperthyroidism). None of the 50 patients with segmental vitiligo showed any thyroid dysfunction (P = 0.047). There was no significant difference in the incidence of thyroid disease between children and adolescents with vitiligo and the control group, in which seven of 122 (5.7%) showed thyroid dysfunction. Conclusion In this study, we demonstrated the characteristics of children and adolescents with vitiligo and also observed no significant difference in the incidence of thyroid disease between children and adolescents with vitiligo and the control group.  相似文献   
72.
73.
Objective: To investigate the cytotoxic, antioxidant and antibacterial activities of ethanolic and aqueous crude extracts of Nerium oleander(N. oleander) leaves. Methods: Cytotoxic activities were evaluated by WST-1 bioassay on two human cancer cell lines, namely human colon adenocarcinoma cell line HT-29 and human breast cancer cell line MDA-MB-231. The antioxidant property of N. oleander extracts was assessed by DPPH scavenging and he agar disc diffusion method was used for the determination of an毬-carotene bleaching tests. Ttimicrobial activity against different strains. Results: Using cell viability indices, the WST-1 test revealed that both extracts reduced cell viability in both cell lines. Our results also showed that aqueous extract was more active than ethanolic extract, with IC50 values of(1.67±0.22) μg/mL and(2.36±0.44) μg/mL on MDA-MB-231 cells, and(2.89±0.35) μg/mL and(5.09±0.52) μg/mL on HT29 cells, respectively. The study of the antioxidant activity showed that N. oleander extracts had a considerable scavenging capacity and exerted a significant preventive effect against the oxidation of 毬-carotene by the peroxide radicals. However, the antibacterial test showed that both ethanolic and aqueous extracts of N. oleander had a moderate antibacterial effect limited only to Gram-positive bacteria. Conclusions: Our results shows that N. oleander aqueous and ethanolic extracts have significant cytotoxic activities against tumor cell lines and possesses a strong antioxidant capacity, suggesting the presence of active compounds in N. oleander leaves that could be a potential source of phytochemicals with high medicinal value to be used in cancer treatment and prevention.  相似文献   
74.
75.
  • The use of percutaneous mechanical support devices is becoming more embedded within the therapeutic armamentarium for patients presenting with decompensated heart failure, cardiogenic shock, and patients undergoing high risk PCI.
  • The Aortix device offers a new approach to percutaneous support that appears to be safe to implement and overcomes some of the drawbacks of the extant devices.
  • Further investigation remains warranted to evaluate its ultimate utility and place among the approach to the patient in need of circulatory support.
  相似文献   
76.
Alawi K, Mitros FA, Bishop WP, Rayhill S, Wu Y. A reduced segment II/III graft for neonatal liver failure with absence of detectable hepatocytes. A case report and literature review.
Pediatr Transplantation 2011: 15:e60–e63. © 2010 John Wiley & Sons A/S. Abstract: When hepatic failure occurs in newborns, most cases are because of viral hepatitis, metabolic diseases, and neonatal hemochromatosis. It is rare to have liver failure presenting in the first day after birth. We report a unique case of a newborn baby with liver failure in the first day of life who received a reduced segment II and III graft when she was 19 days old and became the youngest survivor of LDLT. Common and rare causes of liver failure in this age group were excluded by appropriate testing. She underwent a liver biopsy that showed a liver devoid of hepatocytes. Similar pathological findings were found in the explanted liver. She was discharged from the hospital with normal graft function three months after the transplant.  相似文献   
77.
78.
Vitrectomy and endoresection is an alternative to enucleation for the treatment of large malignant choroidal melanoma. We report a rare case of extensive recurrence of choroidal malignant melanoma with extraocular extension 11 years after surgical endoresection without adjuvant treatment.  相似文献   
79.
The effectiveness and safety of a very low molecular weight heparin fraction were evaluated in the prevention of deep-vein thrombosis in patients confined to bed due to hemiplegia consecutive to a recent cerebral infarction. CY 222 was administered within 48 hours of the stroke by one single daily subcutaneous injection of 0.6 ml (= 15,000 U AXa IC) during 14 days. This randomized pilot study involved 30 patients. The effects of CY 222 were assessed in a group of 15 patients compared with a control group of 15 untreated patients. No deep-vein thrombosis was detected by the labelled fibrinogen test in the treated group, as against 12 patients in the control group. Six patients (3 in each group) died during the study. One case of lethal pulmonary embolism was observed and confirmed at autopsy in the control group. In the remaining 5 patients, no systematic autopsy which would have asserted the absence of pulmonary embolism or drug-induced haemorrhage was performed. Numerous standard laboratory tests confirmed that CY 222 was well tolerated.  相似文献   
80.
Dai  CH; Krantz  SB; Zsebo  KM 《Blood》1991,78(10):2493-2497
To understand the factors that regulate the early growth and development of immature erythroid progenitor cells, the burst-forming units-erythroid (BFU-E), it is necessary to have both highly purified target cells and a medium free of serum. When highly purified human blood BFU-E were cultured in a serum-free medium adequate for the growth of later erythroid progenitors, BFU-E would not grow even with the addition of recombinant human interleukin-3 (rIL-3), known to be essential for these cells. However, the addition of recombinant human stem cell factor (rSCF), which supports germ cell and pluripotential stem cell growth, stimulated BFU-E to grow equally well in serum-free as in serum-containing medium. Limiting dilution studies showed that rSCF acts directly on the BFU-E that do not require accessory cells for growth. Furthermore, rSCF was necessary for BFU-E development during the initial 7 days of culture, until these cells reached the stage of the late progenitors, the colony-forming units-erythroid (CFU-E). These studies indicate that early erythropoiesis is dependent on the direct action of SCF that not only affects early stem cells but is continually necessary for the further development of committed erythroid progenitor cells until the CFU-E stage of maturation.  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