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   645篇
  免费   82篇
  国内免费   3篇
耳鼻咽喉   1篇
儿科学   50篇
妇产科学   20篇
基础医学   97篇
口腔科学   31篇
临床医学   113篇
内科学   124篇
皮肤病学   14篇
神经病学   40篇
特种医学   68篇
外科学   22篇
综合类   15篇
预防医学   56篇
眼科学   11篇
药学   31篇
肿瘤学   37篇
  2024年   2篇
  2023年   11篇
  2021年   7篇
  2020年   5篇
  2019年   5篇
  2018年   17篇
  2017年   11篇
  2016年   11篇
  2015年   12篇
  2014年   19篇
  2013年   27篇
  2012年   5篇
  2011年   16篇
  2010年   24篇
  2009年   38篇
  2008年   25篇
  2007年   16篇
  2006年   15篇
  2005年   32篇
  2004年   20篇
  2003年   16篇
  2002年   16篇
  2001年   20篇
  2000年   12篇
  1999年   26篇
  1998年   23篇
  1997年   34篇
  1996年   39篇
  1995年   28篇
  1994年   22篇
  1993年   18篇
  1992年   8篇
  1991年   5篇
  1990年   7篇
  1989年   21篇
  1988年   10篇
  1987年   6篇
  1986年   16篇
  1985年   11篇
  1984年   8篇
  1983年   8篇
  1982年   12篇
  1981年   7篇
  1980年   10篇
  1978年   6篇
  1977年   4篇
  1976年   8篇
  1972年   3篇
  1925年   1篇
  1911年   1篇
排序方式: 共有730条查询结果,搜索用时 15 毫秒
91.
Hemophilia A: carrier detection and prenatal diagnosis by DNA analysis   总被引:2,自引:0,他引:2  
In this study, we used DNA polymorphisms for carrier detection and prenatal diagnosis of hemophilia A in a large group of Italian families. The restriction fragment length polymorphisms (RFLPs) investigated were the intragenic polymorphic Bc/I site within the factor VIII gene; the extragenic multiallelic Taq I system at the St14 locus; and the extragenic Bg/II site at the DX13 locus. The factor VIII probe was informative in 30%, St14 in 82%, and DX13 in 60% of obligate carriers. The combination of factor VIII-Bc/I and St14-Taq I showed that 91% of obligate carriers were heterozygotes for one or both; with all three probes, only 4% of obligate carriers were noninformative. In families clearly segregating for hemophilia A, RFLP analysis allowed us to define the carrier status for the hemophilia A gene in all 27 women tested. RFLP analysis allowed us to exclude the carrier status in 39 of 45 female relatives of sporadic patients. The combination of RFLP analysis and biological assay of factor VIII allowed us to identify a de novo mutation in the maternal grandfather in 7 of 12 of the families with sporadic cases, for which members of three generations were available for study. Nine of 10 couples requesting prenatal diagnosis provided informative RFLP DNA pattern. Carrier status was excluded in two women, two fetuses were shown to be female, and prenatal diagnosis was carried out in five pregnancies by DNA analysis. Prenatal testing was successful in three instances and failed in two because a sufficient amount of chorionic villous DNA was not obtained for the analysis.  相似文献   
92.
Beutler  E; Dyment  PG; Matsumoto  F 《Blood》1978,51(5):935-940
An 11-yr-old child with mild chronic hemolytic anemia was found to have decreased red cell hexokinase activity in spite of the reduced mean age of her red cell population. Similar decreases in red cell hexokinase activity were documented in the patient's parents and in one sib. The red cells were morphologically normal. Red cell 2,3-DPG levels were normal and ATP and glucose-6-phosphate levels were diminished. The kinetic properties, electrophoretic mobility, and thermal stability of the residual red cell hexokinase were normal or nearly so. Glucose consumption of the hexokinase-deficient cells was not appreciably decreased, probably because less of the potent inhibitor glucose-6- phosphate was present in the erythrocytes. It is likely, although not certain, that in this patient nonspherocytic hemolytic anemia resulted from hexokinase deficiency.  相似文献   
93.
A recently described putative tumor suppressor gene, the cyclin- dependent kinase 4 inhibitor (p16), has been shown to be altered by deletions and/or point mutations in various human cancers. To assess the incidence and clinico-biologic correlations of p16 homozygous deletion in hemopoietic tumors, we studied a panel of 244 DNA samples representative of distinct acute (99 cases) and chronic (57 cases) leukemia subtypes, myelodysplastic (22 cases) and myeloproliferative (15 cases) syndromes, and lymphomas (51 cases). A 361-bp probe complementary to the p16 exon 2 gene sequences was generated by polymerase chain reaction and used in Southern blot hybridization against these tumor DNAs. Homozygous deletions of p16 (p16-/-) were detected in 10 of 58 (17%) cases of acute lymphoblastic leukemia (ALL) of either B or T lineage and in no other tumors. Single-strand conformation polymorphism analysis of p16 exons 1 and 2 was also performed in 40 of the 58 ALL cases and in 16 lymphomas. In no cases were point mutations detected. The comparison of clinical features at presentation in p16-/- and in p16 germline ALL cases showed a greater leukemic cell mass (P = .001) and higher white blood cell counts (P = .01) in the former group. Two ALL cases in which diagnostic and relapse DNA samples were available showed p16-/- in both specimens. We conclude that homozygous p16 gene deletions characterize a subset of ALL with features of aggressive disease.  相似文献   
94.
95.
Role of transforming growth factor beta in peritoneal fibrosis   总被引:11,自引:0,他引:11  
SUMMARY: Technique survival of peritoneal dialysis is seriously limited by the development of peritoneal fibrosis. the mesothelial cell layer lining the peritoneum is important in the pathogenesis of peritoneal fibrosis. Mesothelial cells are able to produce transforming growth factor beta (TGF-β), and respond to stimulation by this cytokine. In this review, we will detail the evidence available so far for the role of the complex interaction between TGF-β and mesothelial cells in the development of peritoneal fibrosis.  相似文献   
96.
    
Ohne Zusammenfassung  相似文献   
97.
98.
99.
Bradley  WG  Jr; Schmidt  PG 《Radiology》1985,156(1):99-103
Subarachnoid hemorrhage has a much higher intensity in magnetic resonance (MR) images with the passage of time. Acute subarachnoid hemorrhage is difficult to see; within 1 week its appearance has become intensified on T1-weighted images. Different concentrations of blood and lysed red blood cells in cerebrospinal fluid (CSF) were examined spectroscopically but did not significantly alter T1 and T2 relaxation of CSF acutely. Ultraviolet visible spectroscopy of bloody CSF stored hypoxically for 3 days showed the presence of methemoglobin. The iron in methemoglobin is paramagnetic; in combination with water this facilitates T1 relaxation. It is concluded that methemoglobin formation with T1 shortening at least partially accounts for the increasing intensity of the MR appearance of subarachnoid hemorrhage over time in the central nervous system and may also explain the intense appearance of subacute hemorrhage in MR images elsewhere in the body.  相似文献   
100.
朝藿素D的分离和结构   总被引:6,自引:0,他引:6  
从朝鲜淫羊藿(Epimedium koreanum)地上部分分离得到一新黄酮成分(I)和一已知化合物(II)。经光谱解析,证明I的结构为5,7,3',4'-tetrahydroxy-5'-prenylflavone,命名为朝藿素D(epimedokoreanin D);II为2-hydroxy-3,4,6,7-tetramethoxy-9,10-dihydrophenanthren。  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