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   437581篇
  免费   36050篇
  国内免费   13233篇
耳鼻咽喉   4284篇
儿科学   9498篇
妇产科学   6199篇
基础医学   33502篇
口腔科学   10348篇
临床医学   47963篇
内科学   64771篇
皮肤病学   5050篇
神经病学   19945篇
特种医学   14327篇
外国民族医学   65篇
外科学   43219篇
综合类   69898篇
现状与发展   55篇
一般理论   26篇
预防医学   39803篇
眼科学   4675篇
药学   41445篇
  495篇
中国医学   41031篇
肿瘤学   30265篇
  2024年   1526篇
  2023年   8069篇
  2022年   14595篇
  2021年   19656篇
  2020年   18996篇
  2019年   19071篇
  2018年   17543篇
  2017年   16770篇
  2016年   16611篇
  2015年   15820篇
  2014年   29169篇
  2013年   32457篇
  2012年   25465篇
  2011年   27466篇
  2010年   22117篇
  2009年   20039篇
  2008年   19341篇
  2007年   19983篇
  2006年   17778篇
  2005年   15409篇
  2004年   12801篇
  2003年   11451篇
  2002年   9412篇
  2001年   8317篇
  2000年   7055篇
  1999年   5781篇
  1998年   4965篇
  1997年   4599篇
  1996年   3823篇
  1995年   3576篇
  1994年   3232篇
  1993年   2597篇
  1992年   2434篇
  1991年   2152篇
  1990年   1836篇
  1989年   1711篇
  1988年   1627篇
  1987年   1387篇
  1986年   1245篇
  1985年   2711篇
  1984年   2841篇
  1983年   1798篇
  1982年   2365篇
  1981年   1722篇
  1980年   1473篇
  1979年   1284篇
  1978年   1020篇
  1977年   794篇
  1976年   931篇
  1975年   600篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Aim: There is strong evidence that hepatocellular apoptosis is not only initiated by circulating blood cells which become adherent within the endotoxemic liver, but also contributes to further sustain the inflammatory cell-cell response. Methods: Because previous studies assumed the importance of the role of cellular cross-talk in mediating inflammatory liver injury, we herein examined the activation of Kupffer cells (KCs) and their spatial coincidence with intrahepatic leukocyte adherence and hepatocellular apoptosis at 6 h after intraperitoneal exposure of rats with lipopolysaccharide (10 mg/kg). Results: In vivo multifluorescence microscopy revealed liver injury including nutritive perfusion failure, tissue hypoxia, leukocyte accumulation, as well as KC activation and parenchymal apoptotic cell death. Detailed spatial analysis revealed frequent colocalization of activated KCs with apoptotic hepatocytes. Colocalization was absent in saline-treated controls.Colocalization was confirmed by histochemistry, which showed ED1-positive KCs neighboring and engulfing TUNEL-positive hepatocytes. Colocalization of KCs with leukocytes ranged between 4% and 5% and did not increase in endotoxemic animals. Taken together, the present results indicate that apoptotic cell death of hepatocytes may stimulate phagocytosis by neighboring KCs. Direct KC-leukocyte contact seems not to be mandatory for cellular communication in the process of hepatocellular apoptosis. Conclusion: With respect to the fundamental importance of cell apoptosis, improved knowledge of these cell-cell interactions might allow the development of new therapeutic strategies through the regulation of apoptotic cell death.  相似文献   
962.
AIM: The aim of this pilot study was an investigation on photodynamic therapy (PDT) whether it is a good alternative for treating periungual and subungual warts of the hands. STUDY DESIGN: Twenty patients (mean age: 30.5 years) with a total of 40 periungual and subungual warts were treated with PDT. A photosensitizer, 20%delta-aminolevulinic acid was applied on the warts. After a mean incubation time of 4.6 h (SD: 1.2), the warts were irradiated with the VersaLight for 5-30 min (15.2 +/- 4.3 min). RESULTS: After a mean of 4.5 treatments a mean clearance of 100% was achieved in 90% of the patients. One patient (5%) showed a clearance of 50% and another showed no improvement. The subungual or periungual location of the wart had no influence on the number of treatments or end result (P > 0.05). There were two recurrences during the mean follow-up period of 5.9 months (SD: 7.6). Besides mainly pain and hyperpigmentation, most treatments had no side-effects. CONCLUSION: PDT can offer a good alternative for treating periungual warts of the hands. Larger studies are indicated.  相似文献   
963.
改良犬原位背驮式肝移植的解剖学观察   总被引:1,自引:0,他引:1  
目的观察犬肝脏解剖学特点,探索建立改良的犬同种异体原位背驮式肝移植模型。方法对15只杂交犬的肝脏进行活体和尸体标本的解剖观察。结果犬肝共分7叶,门静脉分左右支进入肝脏,门静脉左支供应约70%肝组织(Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ叶),门静脉右支供应约30%肝组织(Ⅵ、Ⅶ叶),分别阻断门静脉左、右支后5 min左右门静脉压力达到峰值,并迅速回复至门静脉正常压力值上限范围内;肝动脉和胆管与门静脉分支伴行进入各肝叶;左肝静脉粗大,可以作为肝静脉重建的流出道,其余3~6支肝静脉可以分别结扎,肝后下腔静脉易于与肝脏分离。结论犬肝的解剖学特点适宜于建立改良的原位背驮式肝移植模型。  相似文献   
964.
慢性乙型病毒性肝炎治疗新方法   总被引:2,自引:0,他引:2  
就当前慢性乙肝治疗的新方法、新进展作一综述。  相似文献   
965.
Introduction Failure to enter the coronary sinus (CS) with a guiding catheter and entering its tributaries remains challenging in left ventricle (LV) pacing lead implants for cardiac resynchronization therapy (CRT). A dual telescoping catheter system (8F outer/6F inner) is designed to provide the ability to adjust the catheter curve size, shape and/or reach to the patients’ anatomy avoiding the need for catheter change. Methods Five different designs for CS cannulation were randomly tested in 64 patients scheduled for CRT device implant. Results In 33 consecutive patients three adaptable telescoping guiding catheter systems were tested per patient, the adaptable catheters had higher overall cannulation success rates (68, 63 and 62%) compared to the fixed shape catheter (46%) and an greater cannulation success rate when the CS location was not known (70, 53 and 72% vs 33% for the fixed shape). In a second group of 31 CRT patients the two telescoping catheters had similar high levels of success (71–80%), with or without using the inner catheter. Conclusions The telescopic system is adaptable to a wide range of anatomical variations in patients and can result in a higher CS cannulation success rate due to its adjustability in the RA in search for the CS ostium. On top of this the inner catheter allows for sub-selecting the CS tributaries.  相似文献   
966.
BACKGROUND: The mainstay of treatment for pemphigus is systemic corticosteroids. Different adjuvants have been used to reduce side-effects of long-term corticotherapy. Gold is an anti-inflammatory drug used in autoimmune diseases, whose use has waned with the advent of new immunosuppressive agents. OBJECTIVE: To study the outcome of the use of intramuscular gold treatment of pemphigus vulgaris refractory to previous therapies. METHODS: Thirteen patients with pemphigus vulgaris who had failed to respond to several prior therapies were treated with aurothiomalate, as a steroid-sparing agent. Patients were monitored to assess disease activity and gold toxicity. RESULTS: Seven patients achieved complete remission. Four patients were able to taper prednisone doses, although pemphigus flared when prednisone was discontinued or reduced. Toxicity was observed in the other two patients. CONCLUSIONS: In 53.4% of the patients, the use of chrysotherapy resulted in the complete clearing of the disease, discontinuation of all systemic therapies and induced a long-term clinical remission. Prednisone doses were able to be reduced in the remaining 46.6%. Any side-effects were reversible with drug discontinuation. Gold therapy showed efficacy as a secondary line treatment in refractory pemphigus vulgaris.  相似文献   
967.
摘要:包装内气氛与包装材料选择性透气性是影响果蔬气调包装质量的主要因素。对青豌豆采用6组不同初始气体组分、3种包装材料进行气调包装,在5℃,相对湿度85%的环境下贮藏7d后,测定青豌豆的相关质量指标,并与未包装产品进行比较,结果表明气调包装对青豌豆保鲜效果显著;在此基础上,用主成分分析法构造了气调包装产品质量的综合评价模型,对气调包装青豌豆质量进行综合评价,得出青豌豆气调包装的最佳初始气体组分,分析了不同包装材料对青豌豆气调包装质量的影响。  相似文献   
968.
Immunosuppression trends for solid organ transplantation have undergone a perceptible shift over the past decade. This period is of interest because it was during this time that the Food and Drug Administration (FDA) expanded the variety of medications to allow for alternatives in immunosuppressive management. An organ-by-organ review of SRTR data identifies several important trends. Antibody induction continues to be used for the majority of kidney (70%) , simultaneous pancreas-kidney (SPK, 79%) pancreas after kidney (PAK, 74%), and intestine recipients (74%). It is used for under half of thoracic organ recipients and remains uncommon for liver transplant recipients (20%). The type of antibody preparation utilized has shifted from muromonab-CD3 and horse ATG to rabbit ATG and monoclonal anti-IL-2 receptor antagonists. Calcineurin inhibitors continue to be used for maintenance immunosuppression for most recipients, although there has been a shift from cyclosporine to tacrolimus. A clear transition is apparent in the choice of antimetabolite from azathioprine to mycophenolate mofetil. Although corticosteroids continue to be used as maintenance immunosuppression for most recipients prior to discharge, there is evidence that efforts of steroid avoidance protocols are having an impact across all organs, as slight decreases in their use have been observed.  相似文献   
969.
目的 探索单光子发射计算机断层扫描(SPECF)在脑外伤评估及预后方面的价值的依据。方法 28例中、重度颅脑损伤患者分别于伤后3天、10天及3~4周接受SPECF、CT检查及临床评定。3个月后所有患者行脑外伤综合征的临床测试,对首检SPECF显像阳性者复查SPECF,分析首检SPECF显像阳性者与损伤程度的关系,动态观察SPECF显像与预后的关系。结果 SPECF显像阳性与脑损伤程度有关,首检SPECF显像阳性提示预后良好,复查SPECF显像阳性提示多出现脑外伤综合征。对幕上损伤患者表现的小脑症状、体征可以做出合理的解释。结论 在中至重度颅脑损伤后SPECF显像与CT扫描比较更敏感,脑SPECF具有无创性、功能性及灵敏性高等特点,是脑外伤后功能评估、预后判断及临床研究的可靠方法。  相似文献   
970.
X线透视导航技术在创伤骨科的应用   总被引:6,自引:3,他引:3  
X线透视导航技术对创伤骨科尤为重要。因为术前骨折块及骨折移位的方向可发生改变,所以需在术中将骨折块整复对位后,才能进行透视图像的获取和导航手术操作。X线透视导航技术的优点包括减少X线暴露的时间、准确放置植入物、术中适时测量评估及改善创伤骨科的微创操作。随着软件和硬件的不断改进及发展,许多需要术中X线透视监控的手术操作现在都可以借助X线透视导航技术完成。我们过去四年的临床经验已证实X线透视导航技术的优点及不断扩大的应用领域。X线透视导航技术在不断进展,因此需要更多的临床实践来评价此技术的使用价值。另外,X线透视导航系统在虚拟外科环境的外科培训和评价中发挥重要作用。这一技术将不仅为年轻外科医生提供实践机会,而且也将产生设计外科技术资格客观评价系统的新领域。  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