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   1620篇
  免费   112篇
  国内免费   5篇
耳鼻咽喉   27篇
儿科学   123篇
妇产科学   25篇
基础医学   204篇
口腔科学   22篇
临床医学   116篇
内科学   324篇
皮肤病学   36篇
神经病学   83篇
特种医学   48篇
外科学   232篇
综合类   43篇
一般理论   1篇
预防医学   83篇
眼科学   34篇
药学   154篇
中国医学   10篇
肿瘤学   172篇
  2023年   11篇
  2022年   33篇
  2021年   57篇
  2020年   33篇
  2019年   47篇
  2018年   49篇
  2017年   41篇
  2016年   44篇
  2015年   52篇
  2014年   53篇
  2013年   57篇
  2012年   101篇
  2011年   79篇
  2010年   46篇
  2009年   52篇
  2008年   84篇
  2007年   75篇
  2006年   74篇
  2005年   59篇
  2004年   52篇
  2003年   48篇
  2002年   47篇
  2001年   49篇
  2000年   45篇
  1999年   44篇
  1998年   17篇
  1997年   10篇
  1996年   14篇
  1995年   19篇
  1994年   11篇
  1993年   9篇
  1992年   37篇
  1991年   24篇
  1990年   29篇
  1989年   27篇
  1988年   24篇
  1987年   22篇
  1986年   19篇
  1985年   21篇
  1984年   21篇
  1983年   14篇
  1982年   6篇
  1980年   8篇
  1979年   7篇
  1977年   4篇
  1975年   8篇
  1974年   9篇
  1973年   5篇
  1972年   4篇
  1969年   5篇
排序方式: 共有1737条查询结果,搜索用时 15 毫秒
1.
The antiproliferative, cytotoxic and apoptogenic activities of Bufo melanostictus (Indian common toad) skin extract (TSE) on U937 and K562 leukemic cell line has been investigated. TSE significantly (P<0.001) reduced the time-dependent cell proliferation and decreased MTT values in U937 and K562 cells. TSE (IC50 doses) suppressed the proliferating cell nuclear antigen expression in both the cells. It was demonstrated that, TSE (IC50 doses) primarily arrested the U937 and K562 cells at G1 phase of the cell cycle. Confocal microscopy showed the altered fragmented nuclei and apoptotic bodies formation in TSE (IC50 doses) treated U937 and K562 cells. Membrane blebbing, cell surface shrinkage and perforation were observed through scanning electron microscope. TSE-induced DNA fragmentation in U937 and K562 cells was reflected in single-cell gel electrophoresis. TSE significantly (P<0.001) increase the length-width ratio of DNA mass as compared to control in comet assay. The flow cytometric analysis of annexin-V binding to the cancer cells further supported the apoptotogenic activity of TSE. The effect of TSE on normal human peripheral blood mononuclear cells viability and cytotoxicity was studied in culture and found to be less cytotoxic than on the U937 and K562 cells. The findings from the present study suggested that TSE might possess potent antineoplastic agent having antiproliferative, cytotoxic and apoptogenic activity against U937 and K562 myeloid leukemic cells.  相似文献   
2.
3.
The pedicle patch urethroplasty provides an alternative single-stage vascularised graft procedure for the repair of moderately severe hypospadias. Over a 7-year period, 38 primary hypospadias repairs were performed employing this technique. The fistula rate was 18% in the 34 patients reviewed, but there were few other significant complications. The operation is recommended when the urethral plate can be preserved and the penis straightened in boys who are unsuitable for a meatal-based flap.  相似文献   
4.
As in other clinics, pituitary surgery was definitive treatment in less than 50% of cases of acromegaly treated at one institution over several decades. From 1965 to 1989, 24 acromegalic patients who had noncurative pituitary surgery received radiation therapy at the National Institutes of Health, with a basal human growth hormone level of greater than 5 ng/ml as the criterion for active disease. Using megavoltage irradiation, more than 60% of these patients stabilized at a normal hormonal range, and the overwhelming majority had decreasing growth hormone levels with time. No major side effects of irradiation were encountered except panhypopituitarism of varying degrees. The authors evolved a policy of surgery as the first option, followed by irradiation for patients with postoperative growth hormone levels more than 5 ng/ml.  相似文献   
5.
Effect of ethanol on cyclic AMP levels in intact PC12 cells   总被引:4,自引:0,他引:4  
Two subclones of the rat pheochromocytoma cell line, PC12, were used to compare the effects of ethanol on adenylate cyclase activity in isolated membranes with its effects on cyclic AMP accumulation in intact cells. Consistent with previous reports, ethanol increased basal and 2-chloroadenosine-stimulated adenylate cyclase activity in isolated membrane preparations from both subclones. However, ethanol had opposite effects on agonist-stimulated cyclic AMP accumulation in intact cells of the two subclones, enhancing accumulation in one subclone, and inhibiting it in the other. The inhibition of cyclic AMP accumulation did not result from stimulation of phosphodiesterase activity, activation of the inhibitory guanyl nucleotide regulatory protein, Gi, or stimulation of protein kinase C. The results indicate that extrapolation of the effects of ethanol from one cell type to another, or from in vitro to in vivo systems, may be complicated by the interaction of ethanol with regulatory processes that influence second messenger systems, and can differ in various types of intact cells.  相似文献   
6.
Since the clinical significance of CT abnormalities found in bipolar patients remains obscure, we studied 26 DSM-III bipolar patients who had specific CT abnormalities (third ventricle enlargement, and hyperdensity of the caudate, thalamus, anterior frontal white matter, and right temporal lobe) on numerous parameters such as EEG, the Halstead-Reitan Neuropsychological Battery, premorbid personality adjustment, family history of affective disorder, positive and negative symptoms, employment history, and response to lithium carbonate treatment. None of these measures could differentiate between the CT abnormal and CT normal subgroups. The implications of these findings are discussed.  相似文献   
7.
Thirty-six Australian Aboriginal children with urolithiasis were reviewed. Males dominated the series. The age distribution ranged from 8 months to 12 years and nearly 70% were 2 years or younger. Thirty-five patients had upper tract stones. Ultrasound was diagnostic in 35 patients and was falsely negative in one. Dietary factors, dehydration and recurrent diarrhoea are incriminated in the aetiology, because ammonium urate and oxalate were the main constituents of the stones. Malformations of the urinary tract were rare and known metabolic disorders were not seen. Chemical dissolution of the stones was found to be a safe and effective adjuvant in the management of urate stones.  相似文献   
8.
美国著名健康教育专家Lawrence W.Green 提出的健康教育项目设计PRECEDE 诊断评价模式,站在社会健康的宏观高度,全面规划健康教育内容、方式与作用环节,并从项目设计开始就将监测评价纳入项目内容。由于设计思维的缜密与方法的科学性,保证了健康教育项目能够紧紧抓住重点健康问题,做到有的放矢。因此,在模式的引进和使用过程中,应结合我国妇幼卫生的现状和当地的实际情况,设计出适合我国国情的妇幼卫生健康教育项目规划,为发展我国妇幼卫生事业服务。  相似文献   
9.
DRFS装置治疗腰椎滑脱症   总被引:1,自引:0,他引:1  
目的 探讨一种新型脊柱滑脱复位固定装置的临床疗效。方法 对29例腰椎滑脱症患者采用DRFS装置复位固定并脊柱融合术。结果 29例治疗患者获得7~30月随访,平均复位率及脊柱融合率均达100%。结论 DRFS治疗脊柱滑脱复位满意、固定可靠、融合率高,是治疗腰椎滑脱较理想的方法。  相似文献   
10.
The public health effects of pesticides cannot be denied. However, the undesired effects of chemical pesticides have been recognized as a serious public health concern during the past decades. The present study describes the genotoxic effects of two pesticides, namely cypermethrin and carbosulfan, in a murine test system in vivo. The test parameter used was analysis of sister chromatid exchanges (SCE) in bone marrow cells. Both cypermethrin (5, 10 and 20 mg/kg) and carbosulfan (1.25, 2.5 and 5 mg/kg) induced significant increases in the frequency of SCEs (P < 0.001). However, no significant dose-response correlation could be found for either of the pesticides. Carbosulfan induced a cell cycle delay, as evidenced by an increase in average generation time accompanied by accumulation of cells in the first division cycle, but cypermethrin did not induce any such response. The present study indicates that carbosulfan has a higher potential to cause genetic alterations than cypermethrin in mice and may also pose a mutagenic risk to human beings.  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