首页 | 官方网站   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   2119篇
  免费   142篇
  国内免费   45篇
医药卫生   2306篇
  2022年   31篇
  2021年   32篇
  2020年   33篇
  2018年   24篇
  2017年   24篇
  2016年   23篇
  2015年   34篇
  2014年   48篇
  2013年   78篇
  2012年   80篇
  2011年   88篇
  2010年   94篇
  2009年   109篇
  2008年   68篇
  2007年   83篇
  2006年   92篇
  2005年   61篇
  2004年   53篇
  2003年   50篇
  2002年   46篇
  2001年   36篇
  2000年   27篇
  1999年   28篇
  1998年   82篇
  1997年   74篇
  1996年   72篇
  1995年   68篇
  1994年   41篇
  1993年   54篇
  1991年   19篇
  1990年   15篇
  1989年   30篇
  1988年   42篇
  1987年   42篇
  1986年   29篇
  1985年   38篇
  1984年   21篇
  1983年   24篇
  1982年   16篇
  1980年   16篇
  1977年   16篇
  1976年   15篇
  1963年   17篇
  1960年   14篇
  1959年   22篇
  1958年   29篇
  1957年   19篇
  1956年   30篇
  1955年   42篇
  1954年   35篇
排序方式: 共有2306条查询结果,搜索用时 15 毫秒
31.
32.
Aflatoxin B1 (AFB1), a mutagen and hepatocarcinogen in rats and humans, is a contaminant of the human food supply, particularly in parts of Africa and Asia. AFB1-induced changes in gene expression may play a part in the development of the toxic, immunosuppressive and carcinogenic properties of this fungal metabolite. An understanding of the-role of AFB1 in modulating gene regulation should provide insight regarding mechanisms of AFB1-induced carcinogenesis. We used three PCR- based subtractive techniques to identify AFB1-responsive genes in cultured primary rat hepatocyte RNA: differential display PCR (DD-PCR), representational difference analysis (RDA) and suppression subtractive hybridization (SSH). Each of the three techniques identified AFB1- responsive genes, although no individual cDNA was isolated by more than one technique. Nine cDNAs isolated using DD-PCR, RDA or SSH were found to represent eight genes that are differentially expressed as a result of AFB1 exposure. Genes whose mRNA levels were increased in cultured primary rat hepatocytes after AFB1 treatment were corticosteroid binding globulin (CBG), cytochrome P450 4F1 (CYP4F1), alpha-2 microglobulin, C4b-binding protein (C4BP), serum amyloid A-2 and glutathione S-transferase Yb2 (GST). Transferrin and a small CYP3A-like cDNA had reduced mRNA levels after AFB1 exposure. Full-length CYP3A mRNA levels were increased. When liver RNA from AFB1-treated male F344 rats was evaluated for transferrin, CBG, GST, CYP3A and CYP4F1 expression, a decrease in transferrin mRNA and an increase in CBG, GST, CYP3A and CYP4F1 mRNA levels was also seen. Analysis of the potential function of these genes in maintaining cellular homeostasis suggests that their differential expression could contribute to the toxicity associated with AFB1 exposure.   相似文献   
33.
34.
CONTEXT: Pregnancy complications affect many women. It is likely that some complications can be avoided through routine primary and prenatal care of reasonable quality. PURPOSE: The authors examined access to health care during pregnancy for mothers insured by Medicaid. The access indicator is potentially avoidable maternity complications (PAMCs). Potentially avoidable maternity complications are often preventable through routine prenatal care, such as infection screening and treatment. The authors examined the risks of potentially avoidable maternity complications among rural and urban hospital deliveries for groups of mothers defined by race or ethnicity. METHODS: Data are from the year 2000 Nationwide Inpatient Sample (NIS). The stratified sample represents all discharges from 20.5% of community hospitals in the United States. The Nationwide Inpatient Sample identifies hospital locations, but not patients' areas of residence. Analyses, which accounted for the sample design, included calculation of potentially avoidable maternity complication rates by race or ethnicity, chi2, t tests, and multivariate logistic regression. FINDINGS: Within groups defined by race or ethnicity, unadjusted rates for potentially avoidable maternity complications did not differ significantly by hospital location. Holding other factors constant, potentially avoidable maternity complications were less common in rural hospitals than in urban hospitals (odds ratio, 0.78; CI, 0.62 to 0.99). In rural hospitals, African Americans had notably higher risk for potentially avoidable maternity complications than did non-Hispanic whites (odds ratio, 1.72; CI, 1.26 to 2.36). In urban hospitals, risk of potentially avoidable maternity complications was not significantly higher for African Americans. Hispanics and Asians had notably lower risks of potentially avoidable maternity complications in urban hospitals than did non-Hispanic whites. CONCLUSIONS: Providers and policymakers should work to reduce the risks of potentially avoidable maternity complications for African American women in rural areas who are insured by Medicaid.  相似文献   
35.
Most thyroid cancers (90–95%) are well differentiated. Well differentiated cancers of the thyroid are usually confined to the thyroid capsule, making them amenable to isolated thyroid resection. Invasion of the upper aerodigestive tract by these cancers is infrequent and hypopharyngeal invasion is still rare. We report a 51 year old man with thyroid cancer invading the hypopharynx, who was successfully managed with complete resection along with a partial pharyngectomy. He is asymptomatic and disease free eighteen months after surgery. We advocate aggressive surgical extirpation of thyroid carcinoma invading the upper aerodigestive tract.  相似文献   
36.
37.
目的:了解女性吸毒人员社会化基本状况,并对其应对方式进行分析。方法:问卷调查、个案访谈及对在册病案进行回顾性分析及采用单因素Logistic回归分析。结果:诱发女性吸毒的因素众多,采用单因素Logistic回归分析OR值2 0以上,并有显著性意义的因素有:受教育程度、职业状况、婚姻状况、好奇、同伴影响、感情受挫、寻求刺激和减肥。结论:社会化不足是导致女性吸毒、影响其戒毒和保持戒毒后操守的重要因素,有针对性地对女性吸毒人员实施有效的社会化治疗是必要和有效的。  相似文献   
38.
Tear of the distal biceps brachii tendon is an uncommon injury. Ultrasound evaluation of the distal tendon using an anterior approach is often difficult because of technical factors. We describe a new method of ultrasound evaluation of the distal biceps tendon insertion. This involves a posterior approach with the forearm pronated. With pronation of the forearm, the radial tuberosity faces posteriorly, bringing the distal biceps tendon insertion into view. A surgically proven case of distal biceps tendon tear is presented to illustrate our technique.  相似文献   
39.
目的 探讨肾小球足细胞相关蛋白nephrin和podocin在V型狼疮性肾炎(V-LN)发病中的作用.方法 检测V-LN组11例和特发性膜性肾病(IMN)组8例患者的尿常规、24-h尿蛋白定量、尿补体C3及纤维蛋白原降解产物(FDP)、血脂、血清补体及肝肾功能,并行肾组织活检间接免疫荧光染色,激光共聚焦显微镜观察nephrin、podocin表达的变化.结果 24-h尿蛋白定量、血清白蛋白、肌酐、尿补体C3两组间无统计学差异;V-LN组血脂、血清补体C3、C4及尿FDP均低于IMN组;nephrin、podocin表达两组均减弱,但IMN组更明显.结论 Nephrin、podocin表达减弱可能参与V-LN蛋白尿的发生,但V-LN表达减弱不及IMN明显,推测V-LN蛋白尿的发生可能还有其他机制参与.  相似文献   
40.
目的探讨参麦联合川芎嗪注射液对脓毒症小鼠肝脏的保护作用。方法采用盲肠结扎穿孔(Cecal ligation and puncture,CLP)方法诱导形成脓毒症。将雄性成年的昆明小鼠随机分为5组,分别是假手术组、模型组、参麦注射液治疗组、川芎嗪注射液治疗组和参麦联合川芎嗪注射液治疗组。CLP术前24,12,1 h各组小鼠分别腹腔注射参麦注射液和川芎嗪注射液或者等计量的生理盐水。观察CLP造模后24 h各组小鼠血清中肿瘤坏死因子α(TNF-α)、白介素6(IL-6)含量、谷丙转氨酶(ALT)、谷草转氨酶(AST)活性以及肝脏组织中丙二醛(MDA)、髓过氧化物酶(MPO)水平,并观察各组小鼠的存活率及其肝脏组织的病理变化。结果参麦、川芎嗪及参麦联合川芎嗪三组药物治疗组的脓毒症小鼠其死亡率、血清中炎症因子(TNF-α、IL-6)含量、肝脂质过氧化(MDA、MPO)水平、ALT/AST及其肝脏病理损伤程度均较模型组明显减轻,尤以参麦联合川芎嗪给药治疗组疗效最为显著。此外,联合给药治疗组血清中的炎症因子(TNF-α、IL-6)水平较单一用药组显著降低。结论参麦联合川芎嗪注射液较单一用药能够更有效地抑制炎症反应,提高脓毒症小鼠的存活率、减轻肝脏损伤。  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-23

京公网安备 11010802026262号