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   13947篇
  免费   1299篇
  国内免费   458篇
耳鼻咽喉   139篇
儿科学   287篇
妇产科学   161篇
基础医学   1327篇
口腔科学   431篇
临床医学   1603篇
内科学   1718篇
皮肤病学   137篇
神经病学   560篇
特种医学   561篇
外科学   1378篇
综合类   2511篇
现状与发展   1篇
一般理论   7篇
预防医学   1606篇
眼科学   150篇
药学   1434篇
  12篇
中国医学   950篇
肿瘤学   731篇
  2024年   64篇
  2023年   155篇
  2022年   316篇
  2021年   473篇
  2020年   417篇
  2019年   250篇
  2018年   297篇
  2017年   339篇
  2016年   293篇
  2015年   461篇
  2014年   544篇
  2013年   687篇
  2012年   1119篇
  2011年   1073篇
  2010年   877篇
  2009年   835篇
  2008年   872篇
  2007年   863篇
  2006年   748篇
  2005年   631篇
  2004年   522篇
  2003年   418篇
  2002年   376篇
  2001年   354篇
  2000年   332篇
  1999年   186篇
  1998年   95篇
  1997年   77篇
  1996年   77篇
  1995年   81篇
  1994年   72篇
  1993年   60篇
  1992年   115篇
  1991年   135篇
  1990年   108篇
  1989年   91篇
  1988年   62篇
  1987年   91篇
  1986年   100篇
  1985年   89篇
  1984年   73篇
  1983年   65篇
  1982年   47篇
  1979年   63篇
  1978年   48篇
  1977年   43篇
  1975年   43篇
  1974年   48篇
  1972年   46篇
  1969年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Pluronic P-85 (poly(55)(oxypropylene)dipoly(s)(oxyethylene)) was used to form daunorubicin containing micelles. This new carrier was tested in vitro on sensitive and resistant ovarian cancer cell lines. Drug incorporation was measured by cytofluorometry and the cytotoxicity was measured by the tetrazolium formazan XTT assay. ID50 of 0.16 and 25 mu g/ml were obtained for conjugated and free daunorubicin respectively. The results obtained suggest that this approach may be used in combination with a chemotherapeutic agent to overcome multidrug resistance.  相似文献   
52.
Some patients with an 18p- syndrome show dystonia, and a focal dystonia gene has been mapped to chromosome 18p. The authors evaluated the extent of the deletion in three patients with an 18p- syndrome and dystonia using 14 DNA markers on 18p. A common deleted area, covering the DYT7 locus, places the putative dystonia gene between the telomere of 18p and D18S1104 (49.6 cM). Dystonia in these patients may be caused by haploinsufficiency of the DYT7 gene, a new dystonia gene on 18p, or may result from developmental brain anomalies.  相似文献   
53.
54.
The use of theophylline for the treatment of asthma for 45 of the past 50 years has been for its ability to dilate bronchi. The problem has been that at the most effective bronchodilating dose, toxicity was too close for comfort. In the past 5 years, there has been resurgence in theophylline use at lower doses because of some well-documented anti-inflammatory and steroid sparing effects.  相似文献   
55.
Objectives. Mexican Americans (MAs), compared to white non‐Hispanics (WNHs), have higher rates of biliary disease, noninsulin dependent diabetes, and endstage renal disease but lower rates of lung cancer, hip fractures, and mortality from coronary heart disease. Relatively little research has been done to identify other ethnic differences in disease incidence. We used surgical procedure rates to confirm known ethnic differences and to explore our clinical suspicion that MAs have higher rates of appendectomy than WNHs.

Methods. We used a registry of surgical procedures at two teaching hospitals in South Texas to calculate proportional operation ratios (PORs) for MAs versus WNHs. These two hospitals are the primary source of acute hospital care for the indigent in the area. The POR is arithmetically identical to proportional incidence and mortality ratios.

Results. MAs underwent appendectomy proportionally more often than WNHs at both hospitals (POR = 1.41 and 1.75, p < 0.0001). Other significant PORs were consistent with known ethnic disease differences in biliary tract operations, vascular access for chronic hemodialysis, lung cancer, and coronary artery bypass.

Conclusions. These findings support the hypothesis that MAs may undergo appendectomy more often than WNHs and so may be at higher risk of appendicitis.  相似文献   

56.
A group B streptococcus (GBS) isolated from human neonates diagnosed with sepsis and respiratory distress (early-onset disease) produces a polysaccharide exotoxin (GBS toxin) that, when infused in sheep, causes lung pathophysiology similar to that seen in humans. Histological studies have demonstrated that GBS toxin induces a strong inflammatory response in the lung, with pulmonary sequestration of granulocytes and extensive capillary endothelial damage. The susceptibility of humans to GBS toxin is age-dependent and limited to about 4 days after birth. It is rarely evident thereafter. This suggests that the binding of GBS toxin to the target endothelium occurs via specific components in the developing lung endothelial cells of the newborn that are later lost. We report here that GBS toxin can also bind to developing endothelium associated with neoplasia and induce an inflammatory response. GBS toxin was shown by immunohistochemistry to bind to capillary endothelium of human large-cell carcinomas. In nude mice bearing human tumor xenografts, intravenously administered GBS toxin caused tumor necrosis and hemorrhagic lesions, and substantially inhibited the rate of growth of the tumors. In BALB/c mice bearing Madison lung tumors, GBS toxin induced an inflammatory response resulting in marked changes in tumor morphology, including vasodilation, endothelial and tumor cell necrosis, invasion of lymphocytes and macrophages, and capillary thrombosis. In these tumor models, no evidence of toxicity to the vasculature of other tissues was observed. The reported pathophysiology of GBS in human neonates, the lack of disease in non-neonates colonized with GBS, and these results suggest that GBS toxin may have potential as a well tolerated agent in cancer therapy of some human tumors.Abbreviations GBS group BStreptococcus - PBS phosphate-buffered saline This work was supported in part by a grant from the March of Dimes Foundation  相似文献   
57.
58.
茯苓萜类的高效液相色谱指纹图谱研究   总被引:3,自引:1,他引:3  
目的 建立茯苓三萜化合物的指纹图谱。方法 反相高效液相色谱法。结果 道地药材茯苓及不同地区收集的市场商品具有相当稳定的、相似程度很高的指纹图谱。结论 可利用液相色谱的特征峰控制茯苓及其制剂的质量。  相似文献   
59.
目的 探讨99mTc 氮 二 (N 乙基 N 乙氧基二硫代氨基甲酸盐 ) [99mTcN (NOEt) 2 ]应用于肿瘤诊断的可能性并与99mTc 甲氧基异丁基异腈(99mTc MIBI)肿瘤模型显像进行比较。方法 制备99mTcN (NOEt) 2 ,用上行薄层色谱法测定放化纯。各取 4只移植性艾氏腹水癌小鼠分别尾静脉注射99mTc MIBI或99mTcN(NOEt) 2 ,30min、2h、4h后进行全身后位静态显像。利用感兴趣区技术 ,分别计算不同时相肿瘤与头部 (T/H)、胸部 (T/C)、及健侧肢体对称部位 (T/L)的放射性比值。 4h后处死99mTcN (NOEt) 2 显像组小鼠 4只 ,取血并剥离脏器组织及肿瘤组织 ,称重 ,测量放射性计数 ,计算肿瘤与各脏器放射性比值。结果 99mTcN (NOEt) 2 室温下 4h保持稳定。99mTcN (NOEt) 2 选择性地有效的聚集于肿瘤组织。除腹部外其它组织靶 /非靶比值较高 ,注射2h后T/L比值达最高 ,为 4.87。99mTcN (NOEt) 2 显像组与99mTc MIBI显像组比较T/L比值差异有显著性 (P <0 .0 1)。体外测量肿瘤与血、肌肉、肺等脏器的单位重量放射性比值较高 ,与肝、小肠等腹部脏器的单位重量放射性比值较低。结论 在移植性艾氏腹水癌小鼠模型中99mTcN (NOEt) 2 从血液中清除很快 ,肿瘤摄取率高 ,有一定的滞留量 ,靶与非靶比值高 ,图像质量明显优于99mTc MIBI肿瘤  相似文献   
60.
Ling Shu (< 灵枢 >) said, "The essentials of acupuncture lie in the needling techniques."Twenty-six needling techniques recorded in it, such as the "Nine Needling Techniques", "Five Needling Techniques" and "Twelve Needling Techniques",were cried up by the acupuncture doctors in the past dynasties. The authors applied the relevant needling techniques to treat Bi syndrome in clinic and the quite good effects were got.  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