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   1079篇
  免费   26篇
  国内免费   75篇
耳鼻咽喉   1篇
儿科学   47篇
妇产科学   13篇
基础医学   71篇
口腔科学   15篇
临床医学   132篇
内科学   289篇
皮肤病学   35篇
神经病学   28篇
特种医学   259篇
外科学   97篇
综合类   30篇
预防医学   44篇
眼科学   22篇
药学   47篇
中国医学   3篇
肿瘤学   47篇
  2023年   5篇
  2021年   3篇
  2020年   5篇
  2019年   7篇
  2018年   7篇
  2017年   5篇
  2016年   9篇
  2015年   12篇
  2014年   15篇
  2013年   14篇
  2012年   13篇
  2011年   15篇
  2010年   32篇
  2009年   49篇
  2008年   23篇
  2007年   57篇
  2006年   26篇
  2005年   31篇
  2004年   21篇
  2003年   19篇
  2002年   19篇
  2001年   29篇
  2000年   25篇
  1999年   15篇
  1998年   83篇
  1997年   70篇
  1996年   59篇
  1995年   52篇
  1994年   47篇
  1993年   56篇
  1992年   29篇
  1991年   22篇
  1990年   26篇
  1989年   40篇
  1988年   41篇
  1987年   26篇
  1986年   23篇
  1985年   22篇
  1984年   18篇
  1983年   11篇
  1982年   17篇
  1981年   9篇
  1980年   13篇
  1979年   5篇
  1978年   6篇
  1977年   16篇
  1976年   13篇
  1975年   13篇
  1958年   2篇
  1900年   2篇
排序方式: 共有1180条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
A 61-year-old man presented with jaundice, and subsequently underwent an extended left hepatectomy and pancreaticoduodenectomy for a cholangiocarcinoma invading the head of the pancreas. The patient developed sepsis due to a biliary leak at the hepaticojejunostomy. We describe the original use of a biodegradable stent, deployed via percutaneous transhepatic cholangiography into the Roux limb, resulting in good drainage and resolution of sepsis. The chief benefit of this procedure is the lack of need for subsequent removal as well as purported reduced biofilm accumulation. We believe this to be the first reported case of this type and the literature surrounding the subject is also discussed.  相似文献   
46.
Microtubule reassembly in surface-activated platelets   总被引:2,自引:0,他引:2  
White  JG; Krumwiede  M; Sauk  JJ 《Blood》1985,65(6):1494-1503
It is generally accepted that a circumferential microtubule supports the discoid shape of resting platelets. The fate of the many-coiled polymer following platelet activation, however, has been a subject of considerable debate. Morphological investigations have suggested that the circumferential coils are constricted into tight rings around centrally concentrated organelles during platelet shape change. Biochemical studies employing colchicine-binding assays, on the other hand, have indicated that the bundle of microtubules dissolves almost completely within seconds after activation and reassembles in a new location one to four minutes later. The present study has accepted the latter hypothesis in order to examine the second part of the disassembly-reassembly theory proposed in biochemical studies. Platelets exposed to low temperatures sufficient to remove all microtubules were placed on glass slides and microscope grids to cause surface activation during rewarming. The combined stimuli of rewarming and surface activation might have been expected to cause more rapid assembly than warming alone or activation alone. This was not the case. Reassembly of microtubules during rewarming and simultaneous surface activation was not accelerated. In contrast to the constriction of microtubule rings observed during activation in control platelets, the diameters of coils that developed in chilled platelets one to two hours after rewarming and surface activation were twice those of control cells.  相似文献   
47.
PURPOSE: Bowel dysfunction is common in patients with spinal cord lesions. This study aims to determine whether there are any discriminatory findings at anorectal physiologic testing in patients with spinal cord lesions. METHODS: Twelve consecutive patients (6 females) with significant spinal cord lesions who had mixed symptoms of constipation, fecal impaction, and fecal incontinence were evaluated by perfusion manometry and pudendal nerve terminal motor latency. None of the patients had a sphincter defect as evaluated by endoanal ultrasonography. RESULTS: The median age was 54 (range, 40-87) years. Eight (67 percent) of them had had traumatic spinal cord injuries. Other spinal cord lesions included spina bifida, syringomyelia, arachnoid cyst, and spinal cord ischemia after abdominal aortic aneurysm repair. In patients with spinal cord lesions, the mean (range) resting anal canal pressure and maximum squeeze anal canal pressure were 46 (10-100) mmHg and 76 (30-120) mmHg respectively compared with 62 (50-70) mmHg, and 138 (100-180) mmHg, respectively, in healthy controls. Eleven (92 percent) patients had prolonged pudendal nerve terminal motor latency (9 bilateral and 2 unilateral) whereas rectoanal inhibitory reflex was abolished in all 9 patients tested. CONCLUSIONS: Spinal patients with severe bowel symptoms tended to have lower anal canal pressures than healthy controls. Pudendal netropathy and impaired rectoanal inhibitory reflex are common and may be important in the pathogenesis of bowel dysfunction in patients with spinal cord lesions.  相似文献   
48.
The immunophenotypes of lymphoblasts from children with newly diagnosed T-cell acute lymphoid leukemia (T-ALL, n = 101) or T-cell non-Hodgkin lymphoma (T-NHL, n = 31) were analyzed to correlate stage of thymocyte differentiation with clinical features and outcome. The 67 boys and 34 girls with T-ALL were 1 month to 18 years old (median, 8 years) with leukocyte counts ranging from 2 to 810 x 10(9)/L (median, 55 x 10(9)/L). Eighteen of these patients were black, and 70 had a mediastinal mass. Twenty-six boys and five girls with a median age of 9 years (range, 1 to 20 years) had T-NHL. Seven of these patients were black, and 24 had a mediastinal mass. The distributions of thymocyte developmental stages (early [CD7+], intermediate [CD1+ and/or CD4+ and/or CD8+], and mature [CD3+]) in cases of T-ALL and T-NHL were significantly different: 34%, 43%, and 23% v 6%, 62%, and 32% (P = .02). A comparison of the patients' clinical features according to the maturational stage of thymocytes failed to disclose significant differences in the majority of characteristics studied. However, patients with mature-stage T-NHL, with or without the addition of subjects with mature-stage T-ALL, were less likely to have a mediastinal mass (P = .02 for both comparisons). Those with intermediate-stage T-cell malignancy (T-ALL and T-NHL combined) were the subgroup most likely to have a mediastinal mass (P = .01). Response to remission induction therapy was significantly worse in the T-ALL subgroup with an early-stage phenotype: a failure rate of 21% v 0% and 6% for the two more differentiated phenotypic subgroups (P = .007). Event-free survival was not affected by thymocyte maturational stage in cases of either T-ALL or T-NHL. Despite evidence of clinical heterogeneity among the maturational stages of T-cell malignancies in children, these developmental subdivisions do not appear to be critical determinants of outcome once remission is achieved. We conclude that such phenotypes need not be included in the stratification plans for clinical trials using common induction treatment.  相似文献   
49.
Sensitivity of cervical cytology is suboptimal, especially in developing countries such as Mexico, despite available guidelines aimed at improving this. When obtaining cervical samples, whether the samples are taken from the transformation zone and whether abnormal cells are missing must be considered. Cervical secretions (CS) are always present in variable proportions, and when cleaning the cervix, better samples may be obtained. In this study, we analyzed samples obtained with or without cleaning the cervix, and compared their contents in order to determine the sensitivity and specificity of these two methods. Methods: Of 500 patients who underwent cytology and colposcopy, 271 (54.2%) required a second opinion due to a diagnosis of cervical intraepithelial neoplasia (CIN). CS was removed and compared with the clean, second sample (SS) using in both liquid-based cytology. The quality of samples according to the Bethesda System, the presence of CIN, and inflammatory reactions were recorded. The sensitivity and specificity were calculated using biopsy as the gold standard. Results: The SS resulted in a higher proportion of adequate samples being obtained (97.6% vs. 44.8%), and in increased sensitivity (88.2% vs. 58.8%). CIN was detected in the SS 26% more often than in the CS (34 vs. 27 samples), whereas inflammatory reactions were noted more often in the CS (91.4% vs. 74%). Conclusion: Cervical sampling including CS results in lower sensitivity and CIN detection rates, and in more inflammatory reactions. By excluding CS from cervical samples, the sensitivity could be improved and the false negative rate could be reduced.  相似文献   
50.
目的:肝脏可溶性复合物具有保护肝脏、刺激肝组织再生等生物学活性,观察天然物质肝脏可溶性复合物对肿瘤细胞生长增殖的抑制作用.方法:实验于2006-05/2007-02在四川大学华西医院生物治疗国家重点实验室实验肿瘤研究室完成.①分离人胚胎、成年及新生小鼠肝脏组织,生理盐水清洗、剪碎、筛网过滤,用生理盐水制备混悬液,3 000 r/min离心,收集上清,制备肝脏可溶性复合物.②体外实验:用上述不同来源的肝脏可溶性复合物体外处理肿瘤细胞,四甲基偶氮唑盐比色法测定其对乳腺癌细胞EMT6增殖的影响.③体内实验:观察成年鼠肝脏可溶物质对乳腺癌细胞EMT6体内生长的抑制作用及其对荷瘤鼠生存状况的影响,包括不同给药剂量及不同给药途径两个实验,给药途径包括在接种肿瘤细胞部位的对侧腋下、同侧腋下、腹腔注射及灌胃等.结果:①体外实验显示不同来源的肝脏可溶性复合物能明显抑制肿瘤细胞EMT6增殖率,肿瘤增殖抑制率均显著高于血清白蛋白处理组(P<0.05),并呈剂量依赖性.②成年鼠肝脏可溶物质8mg/L组抑瘤率高于2,4 mg/L组(P<0.05),未观察到明显毒副效应.③比较不同给药途径,成年鼠肝脏可溶物质同侧注射组的抑瘤率较其他3组的抑瘤率高(P<0.05),各成年鼠肝脏可溶物质给予组的体质量增长率比相应生理盐水对照组高(P<0.05).④与相应生理盐水对照组比较,在同侧腋下注射成年鼠肝脏可溶物质的小鼠生存期明显延长(P<0.05).结论:肝脏可溶性复合物具有抑制肿瘤细胞生长的作用,并且呈一定的剂量依赖性.不同的给药途径中,在接种肿瘤细胞部位的同侧腋下给药抑瘤效果最好.  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