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   1418112篇
  免费   104696篇
  国内免费   2212篇
耳鼻咽喉   18561篇
儿科学   45195篇
妇产科学   37911篇
基础医学   209411篇
口腔科学   37817篇
临床医学   133092篇
内科学   280102篇
皮肤病学   29842篇
神经病学   117078篇
特种医学   52212篇
外国民族医学   278篇
外科学   201410篇
综合类   27817篇
现状与发展   6篇
一般理论   763篇
预防医学   116361篇
眼科学   32409篇
药学   102598篇
  7篇
中国医学   2203篇
肿瘤学   79947篇
  2021年   11878篇
  2019年   12485篇
  2018年   16410篇
  2017年   12517篇
  2016年   13798篇
  2015年   16021篇
  2014年   22307篇
  2013年   34189篇
  2012年   47186篇
  2011年   50224篇
  2010年   28911篇
  2009年   27673篇
  2008年   47600篇
  2007年   50776篇
  2006年   49984篇
  2005年   49395篇
  2004年   47450篇
  2003年   45403篇
  2002年   43947篇
  2001年   57432篇
  2000年   58158篇
  1999年   49614篇
  1998年   15409篇
  1997年   13977篇
  1996年   14128篇
  1995年   13287篇
  1994年   12362篇
  1992年   39172篇
  1991年   38596篇
  1990年   37292篇
  1989年   36032篇
  1988年   33468篇
  1987年   32726篇
  1986年   31303篇
  1985年   29671篇
  1984年   23031篇
  1983年   20236篇
  1982年   12781篇
  1981年   11615篇
  1979年   21668篇
  1978年   16222篇
  1977年   13494篇
  1976年   12468篇
  1975年   13342篇
  1974年   16136篇
  1973年   15831篇
  1972年   14883篇
  1971年   13806篇
  1970年   13000篇
  1969年   12282篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Operative mortality, postoperative morbidity and follow up data were analyzed retrospectively from 122 consecutive patients, over 65 years old undergoing elective aortocoronary bypass grafting for symptomatic relief of angina pectoris at the Plains Health Centre, Regina, Saskatchewan, from January 1980 to December 1985. There were two in-hospital deaths (operative mortality 1.6%). Definite perioperative myocardial infarction occurred in 12 patients (9.8%). The 120 survivors were followed for a mean of 32 months. There were three deaths during follow-up, giving a five-year probability of survival of 93%. Twenty-three clinical events (including deaths) occurred during follow-up, giving a five-year probability of event free survival of 72%. Ninety percent of patients say they are pleased with their operation. Seventy-eight percent are currently angina free. These data illustrate the effectiveness of aortocoronary bypass grafting in low risk elderly patients with symptomatic coronary artery disease.  相似文献   
992.
The emergence of a near-haploid clone of cells in blast phase chronic myelogenous leukemia is an unusual event. We report such a case and review eight other cases described in the English literature. The significance of the substantial loss of genetic material is discussed as is the phenotypic and genotypic heterogeneity observed in this group of patients.  相似文献   
993.
We evaluated the isoform composition of heavy and light chains of myosin in single muscle fibers from patients with Duchenne dystrophy, myotonic dystrophy, or polymyositis. In all myopathic muscles, there was an increase in the proportion of intermediate fibers which, by analysis of myosin isoforms, fell into two subpopulations, one that contained both fast and slow myosin and another that contained myosin molecular hybrids. The increased proportion of intermediate (or transitional) fibers suggests changes in the equilibrium between fast and slow motor units. These changes could result from regeneration and subsequent maturation of fibers or from direct transformation of mature fibers of one type into the opposite.  相似文献   
994.
995.
Renal vascular reactivity in jaundice   总被引:1,自引:0,他引:1  
Obstructive jaundice is associated with a predisposition to hypotension and acute renal failure that may be related to changes in renovascular responsiveness, particularly to norepinephrine (NE). This study was undertaken to investigate changes in vascular response to NE and to determine how these changes are related to prostaglandins. Kidneys from bile duct-ligated (BDL) rabbits (n = 5) were perfused with Krebs' solution at 7.65 ml/min, and the response to varying boluses of NE (0.78 to 6.24 micrograms) was measured as changes in perfusion pressure. When compared with sham-operated control kidneys (n = 8), a significantly blunted response was seen at all doses tested. The NE response was further assessed by measuring force development in mounted segments of main renal arteries (MRAs) (n = 8) and interlobar arteries (ILAs) (n = 6) from BDL rabbits and sham-operated controls (MRA, n = 8; ILA, n = 6). The dose-response curves were significantly depressed in both MRAs and ILAs from BDL animals. In addition, MRAs from sham-operated control animals exhibited decreased response to NE after incubation for 1 hour in jaundiced serum. This attenuated response of MRAs to NE was prevented when indomethacin (5 mg/kg) was given to BDL rabbits before death (n = 9) or when 10(-6)mol/L of indomethacin was added to jaundiced serum during incubation (n = 6). These results indicate that obstructive jaundice induces a decreased vascular contractile response in rabbits to NE and that this effect is mediated by prostaglandins.  相似文献   
996.
997.
998.
Studies of former prisoners of war (POWs) provide valuable insights into posttraumatic adaptation because they gather information from a large population who survived the traumatic experiences of military captivity. Previous studies of POWs have shown elevated rates of psychiatric symptoms and disorders. This report presents evidence from a longitudinal study of three large, representative, national samples of former POWs. The study finds that depressive symptomatology, as measured by the Center for Epidemiologic Studies Depression Scale, is elevated in World War II POWs from the Pacific and European theaters and in Korean conflict POWs. Decades later, depressive symptomatology is found to be strongly associated with prior treatment in captivity. Differences in depressive symptomatology among the three POW groups can be attributed to captivity-related factors and to buffering factors, such as age at capture and education.  相似文献   
999.
The study was undertaken to examine the effect of nimodipine, calcium channels blocker, on the morphological alterations induced by quinolinic acid (QUIN). The experiment was performed on 21-day-old organotypic rat hippocampal cultures. Nimodipine was applied to the nutrient medium simultaneously with QUIN (both at 100 microM). Ultrastructural changes were evaluated 24 h, 5 and 7 days after the exposure to tested agent. It was shown that nimodipine induced distinct cytoprotective effect, especially considering the development of late neurotoxic injury produced by QUIN. However, the protection was not complete, indicating the participation of the other factors in the pathomechanism underlying structural damage produced by QUIN.  相似文献   
1000.
The study of urinary sediment is essential in laboratory diagnosis. Conventional clinical methods are now used in line with computer-aided techniques and additional microscopy of the sediment elements. The paper provides a brief analysis of clinical situations characterized by appearance in the urine of abnormal numbers of leukocytes, erythrocytes, casts; provides clinical assessment of additional microscopic methods able to accentuate qualitative characteristics of the urinary syndrome; considers possibilities of application of the urinary sediment data in follow-up to improve diagnosis and control on-going treatment.  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