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   16326篇
  免费   810篇
  国内免费   126篇
耳鼻咽喉   152篇
儿科学   324篇
妇产科学   352篇
基础医学   1891篇
口腔科学   412篇
临床医学   1225篇
内科学   5086篇
皮肤病学   413篇
神经病学   1299篇
特种医学   290篇
外科学   2272篇
综合类   96篇
一般理论   8篇
预防医学   1059篇
眼科学   303篇
药学   911篇
中国医学   37篇
肿瘤学   1132篇
  2024年   13篇
  2023年   139篇
  2022年   308篇
  2021年   699篇
  2020年   313篇
  2019年   630篇
  2018年   693篇
  2017年   412篇
  2016年   421篇
  2015年   456篇
  2014年   742篇
  2013年   814篇
  2012年   1480篇
  2011年   1486篇
  2010年   778篇
  2009年   692篇
  2008年   1110篇
  2007年   1110篇
  2006年   961篇
  2005年   912篇
  2004年   848篇
  2003年   675篇
  2002年   687篇
  2001年   76篇
  2000年   72篇
  1999年   90篇
  1998年   101篇
  1997年   97篇
  1996年   67篇
  1995年   45篇
  1994年   46篇
  1993年   39篇
  1992年   26篇
  1991年   21篇
  1990年   20篇
  1989年   17篇
  1988年   13篇
  1987年   10篇
  1986年   9篇
  1985年   7篇
  1984年   14篇
  1983年   9篇
  1982年   11篇
  1981年   12篇
  1980年   11篇
  1979年   8篇
  1975年   11篇
  1971年   10篇
  1970年   5篇
  1967年   4篇
排序方式: 共有10000条查询结果,搜索用时 3 毫秒
31.
Myocarditis and dilated cardiomyopathy (DCM) are common causes of morbidity and mortality in children and adults, most commonly due to infection with coxsackievirus B or adenovirus. Increased expression of the common human coxsackievirus B-adenovirus receptor (CAR) has been reported in patients with DCM. We investigated the CAR gene in patients with acquired or familial myocarditis/DCM for mutations/polymorphisms. Several polymorphisms or intronic substitutions, distant from the intron-exon boundaries, were identified but no mutations. Based upon these data it appears that CAR gene mutations are not a major host determinant in the development of myocarditis and DCM.  相似文献   
32.
The main objective of this study was to determine whether a chemical immunomodulation protocol could reduce the resistance of NOD/LtSz-SCID mice to Plasmodium falciparum infection and provide an improved mouse model for screening the antimalarial activity of new compounds. This model was compared with the presently used immunodeficient Beige/Nude/Xid (BNX) mouse model, using the same protocol, in terms of percentage of infected mice, parasite development, leukocyte response and phagocytosis of P. falciparum infected cells in various organs. Our results show that the combination of the chemical immune modulation protocol with the genetic background of NOD/LtSz-SCID mice results in the development of long-lasting P. falciparum infection in a high percentage of mice. A comparison of the results obtained in the histological study for both mouse models suggests that the higher rate of success in NOD/LtSz-SCID mice could be related to the reduced macrophage recruitment developed in different tissues to remove the parasite from blood.  相似文献   
33.
A frame-shift 9254del5 mutation was independently identified in 12 families, eleven of them with Spanish ancestors, in a BRCA2 screening performed in 841 breast and/or ovarian cancer families and in 339 women with breast cancer diagnosed before the age of 40 at different centers in France and Spain. We sought to analyze in detail the haplotype and founder effects of the 9254del5 and to estimate the time of origin of the mutation. Eight polymorphic microsatellite markers and two BRCA2 polymorphisms were used for the haplotype analyses. The markers were located flanking the BRCA2 gene spanning a region of 6.1 cM. Our results suggest that these families shared a common ancestry with BRCA2 9254del5, which is a founder mutation originating in the Northeast Spanish, with an estimated age of 92 (95% CI 56-141) generations.  相似文献   
34.
Bronchioloalveolar carcinoma is a distinctive subtype of pulmonary adenocarcinoma, without effective therapy, although there have recently been some attempts to use lung transplantation. However, a high post-transplantation local recurrence rate is described with some controversy regarding the possible involved mechanisms, the main possibilities being the lymphatic spread and aerosolization. Presented herein is a case of a bilateral lung transplantation for a bilateral and pneumonic form of non-mucinous bronchioloalveolar carcinoma in a 43-year-old woman. The histological analysis of mediastinal lymph nodes during surgery did not show neoplastic cells. Thirty-five months after transplantation several nodular opacities in donor lungs were detected. Three pulmonary wedge resections were performed showing a non-mucinous bronchioloalveolar carcinoma with the same histological characteristics as the primary. Again, the mediastinal lymph nodes were tumor free. A complete microsatellites molecular analysis was performed to compare the primary and recurrent carcinoma using capillary electrophoresis, showing that the recurrent tumor was generated in a recipient cellular clone. The absence of lymph node metastasis and the molecular evidence of the recipient origin of the neoplasm supports the contamination of the new lungs at the time of implantation as being the reason for the high incidence of recurrence after lung transplantation in this kind of disease.  相似文献   
35.
A novel role for shuttling SR proteins in mRNA translation   总被引:15,自引:1,他引:15  
  相似文献   
36.
Squamous cell carcinoma is one of the most common malignant cutaneous tumors. Several histological variants have been described; the papillary subtype is one of the most infrequent, with only four cases having being reported previously. We report three new cases of this unusual variant of cutaneous squamous cell carcinoma, review the literature and consider the main differential diagnoses. Polymerase chain reaction performed in our three cases did not demonstrate human papilloma virus infection.  相似文献   
37.
We have tested Green Fluorescent Protein (GFP) expressed by a vaccinia virus recombinant as a marker for viral infection. Virus recombinants expressing either wild-type GFP, or a Ser65 to Thr mutated version (GFP-S65T) were used to infect cultured cells, and the appearance of fluorescence was followed during infection by flow cytometry. Although both versions were detectable in infected cells, GFP-S65T gave up to 26-fold brighter fluorescence than wild-type GFP when excited by an argon laser beam (488 nm). In addition, GFP-S65T fluorescence appeared earlier, and infected cells could be detected above background as soon as 1 h after infection. We have used this construct to infect porcine peripheral blood lymphocytes, and show its usefulness to study virus tropism when used in combination with cell-type specific markers. Thus, GFP provides a direct, fast and convenient way to monitor infection by flow cytometry.  相似文献   
38.
Techniques have been developed to culture bovine or porcine vascular cells on polyglycolic acid (PGA) scaffolds to form engineered vessels. Previously, it was shown that smooth muscle cells (SMCs) that were in close proximity to PGA remnants after 8 weeks of culture had lower expression of SMC markers of differentiation and were more mitotic compared with SMCs that were distant from polymer residuals. Modifications of PGA were explored as a means to minimize residual polymer fragments after culture. To hasten degradation, polymer was treated with heat, NaOH, or gamma-irradiation. Differential scanning calorimetry, mass and tensile strength degradation, and inherent viscosity were used to assess polymer characteristics. When polymer was maintained in aqueous conditions, tensile strength of treated PGA degraded to zero within 3 weeks for each treatment. Engineered vessel constructs cultured on NaOH and gamma-treated polymer displayed smooth muscle alpha-actin throughout the vessel wall. Scaffold treatment impacted graft morphology, cellular differentiation, and mechanical integrity.  相似文献   
39.
ABSTRACT

To determine the prevalence of low scores on two neuropsychological tests commonly used to evaluate learning and memory in children. 6,030 healthy children from 10 countries in Latin America and Spain were administered Rey–Osterrieth Complex Figure (ROCF) and the Test de Aprendizaje y Memoria Verbal–Infantil (TAMV-I). Results showed that low scores are common when multiple neuropsychological outcomes (tests and/or scores) are evaluated in healthy individuals. Clinicians should consider the higher probability of low scores in a given individual when evaluating learning and memory using various sets of scores to reduce false-positive diagnoses of cognitive deficits in pediatric populations.  相似文献   
40.
An abnormal chromosome No. 2 was found in the case of a child with an imperforate anus, a recto-vaginal fistula, unilateral atresia of the inner canal, and deformity of the external ear. G-banding studies revealed an insertion of a segment of the short arm into the long arm in one of the chromosomes No. 2 of the proband, the apparent result of a de novo phenomenon of chromosome rearrangement.  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