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   691188篇
  免费   314749篇
  国内免费   55920篇
耳鼻咽喉   7141篇
儿科学   11813篇
妇产科学   5073篇
基础医学   114447篇
口腔科学   10870篇
临床医学   110205篇
内科学   128532篇
皮肤病学   10156篇
神经病学   30604篇
特种医学   26124篇
外科学   77163篇
综合类   179037篇
现状与发展   110篇
一般理论   2篇
预防医学   96218篇
眼科学   24022篇
药学   112408篇
  792篇
中国医学   83460篇
肿瘤学   33680篇
  2023年   8127篇
  2022年   17929篇
  2021年   21974篇
  2020年   21855篇
  2019年   18565篇
  2018年   19781篇
  2017年   24185篇
  2016年   19692篇
  2015年   28456篇
  2014年   33788篇
  2013年   40036篇
  2012年   53543篇
  2011年   58376篇
  2010年   57212篇
  2009年   60721篇
  2008年   49221篇
  2007年   44483篇
  2006年   39644篇
  2005年   32540篇
  2004年   26658篇
  2003年   22801篇
  2002年   19802篇
  2001年   20919篇
  2000年   14020篇
  1999年   14657篇
  1998年   14151篇
  1997年   13937篇
  1996年   15030篇
  1995年   15192篇
  1994年   14944篇
  1993年   13587篇
  1992年   12799篇
  1991年   12180篇
  1990年   11116篇
  1989年   10988篇
  1988年   10549篇
  1987年   9907篇
  1986年   9423篇
  1985年   8485篇
  1984年   6536篇
  1983年   6551篇
  1982年   7615篇
  1981年   7149篇
  1980年   6819篇
  1979年   6650篇
  1978年   5820篇
  1977年   6125篇
  1976年   5748篇
  1975年   5485篇
  1974年   5035篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Staurosporine (3-100 nM), frequently used as a protein kinase C (PKC) inhibitor, increased accumulation of nitrite in the culture medium of rat peritoneal macrophages up to 6 times above the control level. Moreover, when used in combination with the stable analogue of cyclic AMP, dibutyrylcyclic AMP (db cyclic AMP; 0.1 mM), and/or a cytokine, tumour necrosis factor-alpha (TNF alpha; 100 u ml-1), staurosporine synergistically potentiated, up to 30 times, nitrite accumulation. On the other hand, the other PKC inhibitors, calphostin C and H-7 (10 nM-10 microM) were not effective under the same conditions. The staurosporine-induced nitrite accumulation, in both the presence and the absence of TNF alpha and/or db cyclic AMP was effectively inhibited by the protein synthesis inhibitor, cycloheximide, or by the nitric oxide (NO) synthesis inhibitor, NG-monomethyl-L-arginine (L-NMMA). Thus our data suggest that staurosporine may enhance NO production in macrophages via intracellular mechanisms unrelated to the PKC inhibition.  相似文献   
992.
993.
Body composition measured with isotopic dilution was compared with anthropometric measurements. The study was carried out in 47 subjects from both sexes, 65 to 92 years old. Total body water (TBW), anthropometric measurements, and dynamometry were assessed. TBW was significatively higher in men than women and decreased with age. Dynamometry and fatfree mass were well correlated (r=0.73 in males and r=0.58 in females) and significantly different between sexes. A negative correlation was found for dynamometry with age, being significant for women. Linear regression equations to predict TBW from anthropometric measurements in males and females were obtained: Males: TBW(I)=19.349+0.617 weight(kg) — 0.931 mid-arm circumference(cm)+0.122 dynamometry (kg) Females: TBW(l)=−5.531+0.343 weight(kg)-0.213 triceps skinfold (mm)+ 0.148 dynamometry(kg) + 3.424 wrist diameter (cm). This simple model is proposed for use in epidemiological and field studies where other more sophisticated methods can not be applied.  相似文献   
994.
光动力学疗法与局部化疗联合治疗进展期食管贲门癌   总被引:2,自引:0,他引:2  
作应用光动力学疗法(PDT)对进展期食管贲门癌55例进行治疗,并对其中15例联合应用内镜下局部注射抗癌药物。对每一患均先静脉滴注血卟啉衍生物(HPD)5mg/kg,于用药后24,48和72h分别用波长630nm的铜蒸汽激光照射肿瘤部位。联合治疗组除PDT治疗外,于每次光照前肿瘤局部注射5-Fu250~500mg。结果:联合治疗组的近期显效率高于单纯PDT组(P〈0.05)。病例随访6~16月,  相似文献   
995.
硫酸多糖对体外人脐静脉内皮细胞损伤的保护作用   总被引:8,自引:1,他引:7  
研究表明,硫酸多糖体外对多聚阳离子和氧自由基损伤的人脐静脉内皮细胞有保护作用。肝素、硫酸软骨素A抗多聚阳离子损伤作用比同浓度低分子肝素和甘糖酯强。肝素、硫酸软骨素A、甘糖酯抗氧自由基损伤作用优于同浓度低分子肝素。结果显示硫酸多糖有保护血管内皮的作用,其作用可能与所带阴离子基团有关。  相似文献   
996.
In order to investigate the regulatory effect of acupuncture on obesity patients with the Stomach-Intestine Excessive Heat Type, the pre-acupunctureal and post-acupunctural obesity index and biochemical indices of 718 simple obesity patients with Stomach-Intestine Excessive Heat Type were observed. It was showed that the marked weight loss effect was achieved in the cases by acupuncture, and the biochemical indices improved. It suggests that acupuncture had a optimal regulatory effect on the function of nerve, endocrine, digestion and energy metabolism.  相似文献   
997.
用3H-甘露糖标记7721人肝癌细胞表面糖蛋白的N-糖链,经提取和去唾液酸后,用ConA和DSA亲和柱顺序层析将3H-标记的N-糖链分成4个类型和天线数不同的组分来研究维甲酸(RA)对细胞表面N-糖链的影响。结果:10μmol/LRA处理细胞3~5d后,可使C2C2二天线复杂型N-糖链增加,而高甘露糖型及三、四天线,特别是带有C2,6分支结构的复杂型H-糖链减少。用LCA亲和柱还证明二天线糖链中的核心岩藻糖也减少。进一步发现上述改变的酶学机制是RA降低N-乙酰氨基萄葡糖转移酶V和α-1,6-核心岩藻糖转移酶的活力。结论:BA通过改变某些糖基转移酶活力而改变细胞表面糖链结构,这可能是RA使7721细胞诱导分化的机理之-。  相似文献   
998.
A 29 year old Bengali male patient on chemotherapy for angioimmunoblastic lymphadenopathy developed Strongyloides hyperinfection syndrome 3 months after being treated with a single 3 day course of thiabendazole. His complicated hospitalization and successful management are described. Prevention of this potentially fatal disease in immunocompromised patients by early diagnosis and proper management of intestinal strongyloidiasis is emphasized.  相似文献   
999.
Mortality league tables: do they inform or mislead?   总被引:3,自引:0,他引:3       下载免费PDF全文
OBJECTIVE--To examine certain methodological issues related to the publication of mortality league tables, with particular reference to severity adjustment and sample size. DESIGN--Retrospective analysis of inpatient hospital records. SETTING--22 hospitals in North West Thames health region for the fiscal year 1992-3. SUBJECTS--All admissions with a principal diagnosis of aortic aneurysm, carcinoma of the colon, cervical cancer, cholecystectomy, fractured neck of femur, head injury, ischaemic heart disease, and peptic ulcer. MAIN MEASURES--In hospital mortality rates adjusted by disease severity and calculated on the basis of both admissions and episodes. RESULTS--The numbers of deaths from specific conditions were often small and the corresponding confidence intervals wide. Rankings of hospitals by death rate are sensitive to adjustment for severity of disease. There are some differences that cannot be explained using routine data. CONCLUSIONS--Comparison of crude death rates may be misleading. Some adjustment for differences in severity is possible, but current systems are unsatisfactory. Differences in death rates should be studied, but because of the scope for manipulating data, this should be undertaken in a collaborative rather than a confrontational way. Any decision to publish league tables of death rates will be on political rather than scientific grounds.  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