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   2891968篇
  免费   222930篇
  国内免费   5490篇
耳鼻咽喉   38990篇
儿科学   95793篇
妇产科学   80376篇
基础医学   410697篇
口腔科学   85941篇
临床医学   259454篇
内科学   559912篇
皮肤病学   64094篇
神经病学   229218篇
特种医学   112325篇
外国民族医学   698篇
外科学   438753篇
综合类   70404篇
现状与发展   6篇
一般理论   1020篇
预防医学   220595篇
眼科学   68967篇
药学   215932篇
  9篇
中国医学   6469篇
肿瘤学   160735篇
  2018年   30738篇
  2017年   23643篇
  2016年   26151篇
  2015年   29838篇
  2014年   41517篇
  2013年   61796篇
  2012年   84719篇
  2011年   89369篇
  2010年   52897篇
  2009年   49632篇
  2008年   83732篇
  2007年   88698篇
  2006年   89623篇
  2005年   86273篇
  2004年   84131篇
  2003年   80282篇
  2002年   77868篇
  2001年   140994篇
  2000年   145024篇
  1999年   121397篇
  1998年   32905篇
  1997年   29286篇
  1996年   29210篇
  1995年   28206篇
  1994年   26243篇
  1993年   24410篇
  1992年   96163篇
  1991年   93412篇
  1990年   90558篇
  1989年   87350篇
  1988年   80479篇
  1987年   78902篇
  1986年   74980篇
  1985年   71958篇
  1984年   53326篇
  1983年   45786篇
  1982年   26378篇
  1981年   23606篇
  1979年   49418篇
  1978年   34082篇
  1977年   28969篇
  1976年   27183篇
  1975年   28786篇
  1974年   35105篇
  1973年   33743篇
  1972年   31177篇
  1971年   29238篇
  1970年   27043篇
  1969年   25322篇
  1968年   23318篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Sclerotherapy of varicose veins and telangiectasia should be preceded by a directed medical history and physical examination. Factors including the presence of significant venous disease should prompt a more extensive evaluation. Of the physical examination techniques and noninvasive technologies available, Doppler ultrasound provides the most pertinent information, but the potential uses of each method are described.  相似文献   
992.
Summary: T cells and natural killer (NK) cells are presumed to share a common intrathymic precursor. The development of conventional a|3 T lymphocytes begins within the early fetal thymus, after the colonization of multipotent CDl1 71 precursors. Irrevocable commitment to the T lineage is marked by thymus-induced expression of CD25. However, the contribution of the fetal thymus to NK lineage commitment and differentiation remains largely unappreciated. Recently, we demonstrated that the development of functional mouse NK cells occurs first in the fetal thymus. Moreover, the appearance of mature fetal thymic NK cells (NK1.1+/CD 117-) is preceded by a thymus-induced developmental stage (NKl.1+/CD1 17+) that marks lineage commitment of multipotent hematopoietic precursors to the T and NK-cell fates. Commitment to the T/NK bipotent stage is induced by fetal thymic stroma, but is not thymus dependent. Recent data indicate that CD90+/CD117lo fetal blood prothymocytes exhibit NK lineage potential and are phenotypically and functionally identical to fetal thymic NK1,1+/CD1 17+ progenitors. This finding also indicates that full commitment of circulating precursors to the T-cell lineage occurs after thymus colonization. In this review, we discuss recent insights into the cellular and molecular events involved in fetal mouse T and NK lineage commitment and differentiation to unipotent progenitors.  相似文献   
993.
Summary. In this study, we have examined our records for the isolation of Candida tropicalis from clinical specimens of patients with heterogeneous clinical presentations during the past 5 years. We have found that this species ranks third among all yeasts in frequency of isolation from clinical specimens and that the trend of recovery from the specimens is rising over the years. The isolation rate of C. tropicalis was highest from urine specimens (36%) followed by respiratory specimens (22%). The frequency of isolation of C. tropicalis from vaginal specimens was relatively high (14%), however the trend was declining over the years. In general, the high recovery of Candida tropicalis from clinical specimens of patients with variable disease supports the views of this organism being a major pathogen.
Zusammenfassung. Die Studie basiert auf einer Durchsicht der Patientenarchive der letzten fünf Jahre auf die Isolationshäufigkeit von Candida tropicalis aus klinischen Untersuchungsmaterialien von Patienten mit unterschiedlichen klinischen Krankheitsbildern. Diese Hefeart war die dritthäufigste mit steigender Tendenz über die Jahre. Die Isolierungsrate von C. tropicalis war am höchsten aus Urin (36%), gefolgt von Respirationstrakt-Materialien (22%). Die Isolationshäufigkeit aus dem hinteren Scheidengewölbe war relativ hoch (14%), nahm jedoch mit den jahren ab. Allgemein unterstreicht die hohe Isolationsrate von C. tropicalis aus klinischen Untersuchungsmaterialien die ätiologische Bedeutung dieses Erregers.  相似文献   
994.
为探讨脂质过氧化损伤及自由基在新生儿硬肿症发病机理中的作用,将观察对象分为疾病组和对照组,疾病组于入院时,对照组于出生后1周内取静脉血检测血浆脂质过氧化物及红细胞超氧化物歧化酶含量。  相似文献   
995.
996.
There has been a remarkable change in the scenario of therapeutic apheresis in the last 14 years in India. The crude method of manual removal of blood followed by separation of plasma by gravity, keeping it in the bottle for a long time, has now been totally replaced by plasmapheresis, centrifugation, membrane filtration, and immunoadsorption techniques. The indications for use have also changed from a list of limited indications in the beginning to include all immune complex disorders. The clinical beneficiaries have also increased from blood bankers to nephrologists and immunologists in addition to oncologists. Efforts are now underway with the help of the Indian Society for Apheresis (founded in 1985) to popularize the newer methods of cryofiltration, photopheresis and heparin extracorporeal low-density lipoprotein (HELP) and DALI apheresis systems besides the specialized techniques of immunoadsorption using filters, columns, or ligands. This is suggestive of a positive trend for the treatment of immune complex disorders.  相似文献   
997.
998.
999.
1 Intravenous administration of the ganglionic nicotinic receptor agonist DMPP (1,1-dimethyl-4-phenylpiperazinium iodide) into urethane-anaesthetized rats evoked dose-dependent increases in mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). 2 The ganglionic nicotinic receptor antagonists pentolinium and hexamethonium either alone or combined did not inhibit the increase in RSNA and MAP evoked by 50 to 200 μg kg?1 doses of DMPP. The increase in renal sympathetic nerve activity evoked by DMPP occurred as a brief burst in firing. 3 The increase in MAP, but not RSNA, evoked by DMPP in the presence of pentolinium was inhibited by the selective α1-adrenergic receptor antagonist prazosin. 4 The non-selective α-adrenoceptor and NPY receptor antagonist benextramine also inhibited the increase in MAP without inhibiting the increase in RSNA. Surprisingly, the combination of benextramine and pentolinium, or benextramine and hexamethonium, completely blocked the DMPP-evoked increase in RSNA and thus the increase in MAP. 5 The uptake1 antagonist desipramine combined with pentolinium did not affect the DMPP-evoked increases in MAP or RSNA when compared to the responses evoked in the presence of pentolinium alone. 6 Adding the selective M1 muscarinic receptor antagonist telenzepine to pentolinium and prazosin did not inhibit the increase in RSNA evoked by a 100 μg kg?1 dose of DMPP. 7 While the DMPP-evoked increase in MAP in the presence of ganglionic nicotinic receptor antagonists is primarily dependent upon activation of α1-adrenoceptors, the increase in RSNA occurs via activation of ganglionic nicotinic receptors and activation of a mechanism susceptible to blockade by benextramine.  相似文献   
1000.
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