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   264篇
  免费   14篇
耳鼻咽喉   2篇
儿科学   4篇
妇产科学   3篇
基础医学   39篇
口腔科学   5篇
临床医学   29篇
内科学   55篇
皮肤病学   10篇
神经病学   4篇
特种医学   30篇
外科学   22篇
综合类   8篇
预防医学   14篇
眼科学   3篇
药学   41篇
肿瘤学   9篇
  2022年   3篇
  2021年   3篇
  2020年   6篇
  2018年   4篇
  2017年   3篇
  2016年   7篇
  2015年   5篇
  2014年   3篇
  2013年   5篇
  2012年   8篇
  2011年   3篇
  2010年   9篇
  2009年   10篇
  2008年   5篇
  2007年   17篇
  2006年   7篇
  2005年   10篇
  2004年   8篇
  2003年   7篇
  2002年   6篇
  2001年   4篇
  2000年   7篇
  1998年   6篇
  1997年   5篇
  1996年   7篇
  1994年   4篇
  1993年   4篇
  1992年   4篇
  1991年   3篇
  1990年   4篇
  1989年   5篇
  1988年   10篇
  1987年   4篇
  1986年   4篇
  1985年   5篇
  1984年   5篇
  1983年   5篇
  1982年   5篇
  1980年   3篇
  1978年   5篇
  1977年   2篇
  1976年   8篇
  1975年   4篇
  1974年   2篇
  1973年   5篇
  1972年   6篇
  1971年   3篇
  1970年   3篇
  1969年   4篇
  1967年   7篇
排序方式: 共有278条查询结果,搜索用时 15 毫秒
21.
Presumptive somatic cells of the copepod Cyclops kolensis specifically eliminate a large fraction of their genome by the process of chromatin diminution. The eliminated DNA (eDNA) remains only in the germline cells. Very little is known about the nature of the sequences eliminated from somatic cells. We cloned a fraction of the eDNA and sequenced 90 clones that total 32 kb. The following organizational patterns were demonstrated for the eDNA sequences. All do not contain open reading frames. Each fragment contains 1-3 families of short repeats (10-30 bp) highly homologous within families (87%-100%). Most repeats are separated by spacers up to 50 bp long. Homologous regions were found between fragments, motifs from 15-300 bp in length. Among fragments there occur groups in which the same motifs are ordered in the same fashion. However, spacers between the motifs differ in length and nucleotide composition. Ubiquitous motifs (those occurring in all fragments) were identified. Analysis of motifs revealed submotifs, each occurring within several motifs. Thus, motifs may be regarded as mosaic structures composed of submotifs (short repeats). Taken together, the results provide evidence of a high organizational ordering of the DNA sequences restricted to the germline. With this in mind, it appears incorrect to refer to this part of the genome as junk. Moreover, eDNA is redundant for only the somatic cells-its function is to be sought in germline cells.  相似文献   
22.
23.
We report on the cytogenetic findings from a patient with a de novo TNF-receptor-associated periodic syndrome (TRAPS), who showed first symptoms at the age of four months. Thus, he obtained a long-term therapy with cortisone, chlorambucile, methotrexate and cyclophosphamide. At the age of 14 he developed a secondary acute myeloblastic leukemia. Highly complex chromosomal rearrangements were detected after banding analysis. The exact definition of karyotype and the involved breakpoints could only be resolved after application of sophisticated multicolor-FISH techniques: 44,XY,-5,der(6)t(6;7)(6pter right curved arrow 6q12::7p22.2 right curved arrow 7pter or 7pter right curved arrow 7p22.2), dic(7;19)t(6;19;6;7;19;7;19)(19qter right curved arrow 19q12::7p13 right curved arrow 7p11.1::19q12 right curved arrow 19p12 or 19p12 right curved arrow 19q12::7p11.1 right curved arrow 7q21.3::6q12 right curved arrow 6q26::19p13.3 right curved arrow 19p12::6q26-6qter),dic(12;13)(13qter right curved arrow 13p11.2::12p13.1 right curved arrow 12qter),ace(12;13)(13pter right curved arrow 13p11.2::12p13.1 right curved arrow 12pter), -19. The simultaneous presence of two dicentric chromosomes has not been reported previously and is striking, as such chromosomes are suggested to be instable. However, such chromosomes are observed frequently after chemo- or radiotherapy and in secondary, i.e. therapy related AML (tAML). Thus, AML in this case may result from a long-term therapy of TRAPS with methotrexate, cyclophosphamide, chlorambucile and cortisone.  相似文献   
24.
Headache in lacunar stroke   总被引:1,自引:0,他引:1  
The presence of headache within a 72-h interval of stroke onset was investigated in a cohort of 145 lacunar infarcts. Fourteen (10%) experienced diffuse or bilateral headache. Hypertension was less frequent (43 vs 76%; 95% CI: 6 to 60%) and of shorter duration (2.4 vs 7.8 years; t = 2.29; p = 0.02) among patients with headache. Leukoaraiosis was less frequent (40% vs 71%; 95% CI: −57 to −7%) and severe (7 vs 24%; 95% CI: −33 to −2%) in patients with headache. Age, sex, stroke risk factors, type of lacunar stroke, mode of onset, stroke severity, ultrasound and other CT findings were similar in patients with and without headache. No differences in the sixth month neurological or functional outcome were detected between lacunar patients with and without headache. Headache in lacunar stroke cannot be predicted by the clinical characteristics of the stroke and is not due to coexisting cardiembolism, intra or extracranial disease. Hypertensive small-vessel disease is less common and severe in lacunar strokes with associated headache.  相似文献   
25.
Cyclosporin nephrotoxicity in heart and lung transplant patients   总被引:1,自引:0,他引:1  
Twenty-two patients with heart, lung or heart and lung transplants maintained on cyclosporin for periods ranging from 3 months to 10 years developed renal insufficiency which was investigated by renal biopsy. The histopathological changes were: (i) severe vascular and glomerular damage due to thrombotic microangiopathy (TM); (ii) a form of focal segmental glomerulosclerosis (FSGS); (iii) glomerular ischaemia. Rather than being separate entities, these changes appeared to represent a spectrum of pathology, some biopsies showing all three forms of glomerular injury. In all cases the glomerular changes were accompanied by arteriolar and arterial pathology, and we identified novel ultrastructural changes in the arteriolar endothelial basal lamina. Tubular atrophy was a consistent feature, the severity of which reflected the severity of the glomerular sclerosis, and which appeared to be a consequence of glomerular loss. Our findings are consistent with the nephrotoxic effects of cyclosporin being mediated chiefly via damage to preglomerular vessels and glomerular capillary endothelium. From an analysis of the clinical aspects of these cases, the effects of cyclosporin appear to be to some extent idiosyncratic, and therefore not entirely preventable, but strict monitoring of blood cyclosporin levels is essential to minimize the risk of permanent renal damage. Monitoring urinary protein in addition to plasma creatinine may detect the onset of FSGS, as proteinuria precedes creatinine elevation.   相似文献   
26.
27.
Background: This observational study was conducted in a small, 45 bed border static hospital, located in a field area, where no blood bank facilities were available. The present study was conducted to elucidate the blood transfusion practices of this hospital.  相似文献   
28.
Aseries of substituted 2-methylenehydrazino-4-aryl-4-oxobut-2-enoic acids and their anilides and esters were obtained using reactions of 4-aryl-2-hydroxy-4-oxobut-2-enoic acids and their amides and esters with benzophenone hydrazone, benzyl monohydrazone, and triphenylphosphazines. The methyl ester of 2-(1,2-diphenyl-2-oxoethylidenehydrazino)-4-(4-chlorophenyl)-4-oxobut-2-enoic acid was also synthesized by decyclization of 3-(1,2-diphenyl-2-oxoethylidenehydrazino)-5-(4-chlorophenyl)-3H-furan-2-one using methanol. The synthesized compounds exhibit moderate anti-inflammatory, analgesic, and antimicrobial activity.  相似文献   
29.
30.

Purpose

There is a lack of adjudicated and prospectively randomized published outcomes on the use of drug-coated balloons (DCB) to treat dysfunctional arteriovenous fistula in Asian patients. This post hoc subgroup analysis of 112 Japanese participants from the global IN.PACT AV Access trial reports outcomes through 12 months.

Materials and Methods

Participants were treated with DCB (n = 58) or standard non-coated percutaneous transluminal angioplasty (PTA) balloons (n = 54). Outcomes included target lesion primary patency (TLPP), access circuit primary patency, and safety.

Results

Through 6 months, TLPP was 86.0% (49/57) in the DCB group and 49.1% (26/53) in the PTA group (p < 0.001). Through 12 months, TLPP was 67.3% (37/55) in the DCB group and 43.4% (23/53) in the PTA group (p = 0.013).

Conclusion

In this post hoc analysis of Japanese participants from the IN.PACT AV Access trial, participants treated with DCB had higher TLPP through 6 and 12 months compared with PTA.  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