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   28439篇
  免费   2749篇
  国内免费   2259篇
耳鼻咽喉   204篇
儿科学   312篇
妇产科学   314篇
基础医学   3693篇
口腔科学   476篇
临床医学   3886篇
内科学   4576篇
皮肤病学   248篇
神经病学   1444篇
特种医学   1004篇
外国民族医学   21篇
外科学   2961篇
综合类   4493篇
现状与发展   9篇
一般理论   4篇
预防医学   1746篇
眼科学   717篇
药学   2875篇
  32篇
中国医学   1511篇
肿瘤学   2921篇
  2024年   108篇
  2023年   496篇
  2022年   1280篇
  2021年   1641篇
  2020年   1223篇
  2019年   973篇
  2018年   1070篇
  2017年   914篇
  2016年   874篇
  2015年   1380篇
  2014年   1692篇
  2013年   1343篇
  2012年   2013篇
  2011年   2266篇
  2010年   1384篇
  2009年   1090篇
  2008年   1420篇
  2007年   1484篇
  2006年   1411篇
  2005年   1543篇
  2004年   910篇
  2003年   798篇
  2002年   752篇
  2001年   619篇
  2000年   616篇
  1999年   683篇
  1998年   516篇
  1997年   469篇
  1996年   394篇
  1995年   359篇
  1994年   284篇
  1993年   163篇
  1992年   225篇
  1991年   168篇
  1990年   147篇
  1989年   135篇
  1988年   153篇
  1987年   101篇
  1986年   96篇
  1985年   71篇
  1984年   42篇
  1983年   34篇
  1982年   28篇
  1981年   21篇
  1980年   10篇
  1979年   18篇
  1978年   5篇
  1975年   3篇
  1971年   5篇
  1969年   5篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Adenoviruses can cause infections in people of all ages at all seasons of the year. Adenovirus infections cause mild to severe illnesses. Children, immunocompromised patients, or those with existing respiratory or cardiac disease are at higher risk. Unfortunately, there are no commercial drugs or vaccines available on the market for adenovirus infections. Therefore, there is an urgent need to discover new antiviral drugs or drug targets for adenovirus infections. To identify potential antiviral agents for adenovirus infections, we screened a drug library containing 2138 compounds, most of which are drugs with known targets and past phase I clinical trials. On a cell-based assay, we identified 131 hits that inhibit adenoviruses type 3 and 5. A secondary screen confirmed the antiviral effects of 59 inhibitors that inhibit the replication of adenoviruses type 3 or 5. Most of the inhibitors target heat shock protein, protein tyrosine kinase, the mTOR signaling pathway, and other host factors, suggesting that these host factors may be essential for replicating adenoviruses. Through this study, the newly identified adenovirus inhibitors may provide a start point for developing new antiviral drugs to treat adenovirus infections. Further validation of the identified drug targets can help the development of new therapeutics against adenovirus infections.  相似文献   
102.
For the Honghe Bridge project located in Yunnan Province, Southwest China, a steel/ultrahigh-performance concrete (UHPC) composite deck is used in the suspension bridge with a 700 m main span, and the steel stud connectors are used in the 50 mm–thick UHPC layer. To investigate the shrinkage behavior of UHPC and the relevant influence, the in situ time-dependent strain is measured continuously, and within the 20-day curing time, the material behavior is summarized based on test results. This paper proposes a prediction model for UHPC shrinkage which is refined from the widely used B3 model for normal concrete material, and the parameter values are modified and optimized by experimental comparison. Combining the numerical model and the finite element analysis model of the composite deck, the detailed mechanical state in structural parts is studied. For the practical construction, the simulation results indicate that the small thickness of UHPC above the stud and weak bond strength can influence the eventual structural performance greatly. In the discussion of stress distribution at different locations of the deck, the potential crack on the edge and the corner of the UHPC–steel interface and the mechanical damage on the stud connector around are also indicated.  相似文献   
103.
酸枣仁中黄酮类镇静催眠有效成分的研究   总被引:11,自引:0,他引:11  
本文对辽宁产的酸枣仁中的黄酮类成分进行了初步研究,从中分离出一种淡黄色无定形粉末,经鉴定为黄酮碳甙(spinosin)。动物实验证明,酸枣仁中镇静催眠作用的成分不仅是皂甙成分,黄酮也是主要成分之一。  相似文献   
104.
驳骨煎剂促进骨折愈合的实验研究   总被引:19,自引:6,他引:13  
为探讨驳骨煎剂促进骨折愈合的作用机理。选用体重20-30g的NIH小白鼠120只,雌雄各半,随机分为正常组,给药组、对照组。除正常组外,其它各组均采用定点手法折骨术造成小鼠右下肢胫骨中段闭合性骨折,术后7、14、21、28天分批处死小鼠,处死前48小时,经腹腔注射同一批号0.2ml^45Ca-CaCl2溶液,48小时后,断头取向,并解剖出左右胫骨,测定骨痂生长状况及钙沉 积量的变化。结果显示,给药  相似文献   
105.
论中药工业中的中试放大验证   总被引:2,自引:0,他引:2  
本文对中药制药工程技术的四要素之一-中药施工与验证进行探讨,从中药研究成果转化为大规模生产的过程中一般都将发生质的变化,许多重大工程技术问题也往往出现在这一阶段。因此,中试放大验证至关重要,也中药现代化的关键。本文论述了在实现中药大规模生产过程中进行中试放大验证的必要性,主要技术内容,应达到的目标,并就中试放大验证平台的建设,基本功能与任务,运行等进行了详细介绍。  相似文献   
106.
目的:观察溶栓颗粒治疗急性缺血性中风的疗效。方法:将128例急性缺血性中风患者随机分成3组,在一般内科治疗基础上分别口服溶栓颗粒(治疗组)、溶栓胶囊(对照组1)、尼莫地平(对照组2),治疗3周,观察临床疗效。结果:治疗组临床疗效优于对照组1、对照组2(P〈0.05),3组治疗后与治疗前比较症状均有明显改善(P〈0.05),治疗组证候疗效优于对照组1、对照组2(P〈0.05)。结论:溶栓颗粒是治疗急性缺血性中风的有效药物。  相似文献   
107.
目的:观察升麻甙与5-O甲基维斯阿米醇甙对氧化低密度脂蛋白(ox-LDL)致心脏微血管内皮细胞损伤,引起IL-6和TNF-α分泌的影响。方法:采用体外培养的乳鼠心脏微血管内皮细胞,测定其生长曲线及药物的最大无毒浓度后,经升麻甙(50、100、200μg/ml)与5-O甲基维斯阿米醇甙(50、100、200μg/ml)预处理24h,再与ox-LDL(MDA含量为3nmol/ml)共同孵育24h,用ELISA法和放免法分别检测细胞培养液中IL-6和TNF-α的水平。结果:升麻甙与5-O甲基维斯阿米醇甙在50、100、200μg/ml时能够明显抑制ox-LDL引起的内皮细胞IL-6、TNF-α分泌,且呈剂量依赖性。结论:升麻甙与5-O甲基维斯阿米醇甙能够抑制血管内皮细胞产生炎性细胞因子IL-6和TNF-α。  相似文献   
108.
Of 468 diagnosis-related groups identified by the federal government for Medicaid reimbursement, 15 are related to obstetric hospital care. Each diagnosis-related group is considered a distinct group in which cases are homogeneous with respect to resource consumption. Because the diagnosis-related group system is based primarily on data from community and secondary care hospitals, it does not differentiate sufficiently among high-risk obstetric patients seen at tertiary care institutions, such as Florida's Regional Perinatal Intensive Care Centers. We developed an alternative scheme for diagnosis-related groups, called obstetric care groups, using the federal diagnosis-related groups as the model from which to depart. Data collected for 4192 women during a 2 1/2-year period indicate that obstetric care groups provide more homogeneous groups than diagnosis-related groups for our population of high-risk patients. The obstetric care groups differentiate between no complications, one complication, and two or more complications, while the diagnosis-related groups differentiate only between no complications and one or more complications. Also, complications for obstetric care groups are based on only 19 diagnoses that contribute significantly to resource consumption, while the list of possible complications exceeds 200 for diagnosis-related groups. Although the obstetric care group classification system is simpler than that for diagnosis-related groups, it results in a more accurate reimbursement of hospitalization charges for high-risk obstetric care.  相似文献   
109.
In this article we report the results of chorionic villus sampling by a biopsy forceps inserted via the cervix under ultrasonic guidance in 300 pregnancies at risk for thalassemia major. A sufficient amount of chorionic villi for deoxyribonucleic acid analysis by oligonucleotide hybridization was obtained in all cases tested but one, with a success rate of 99.7%. The percentage of fetal loss, expressed as proportion of continuing pregnancies, was 4.8%. To verify the results, we carried out amniocyte deoxyribonucleic acid analysis in all the continuing pregnancies for the first 100 cases and in those in which trophoblast deoxyribonucleic acid analysis showed the heterozygous state for beta-thalassemia for the second 200 cases. At the beginning we had two cases of decidual contamination in such an amount to cause misdiagnosis. Successively more careful elimination of decidual tissue from villi avoided avoided this pitfall. These results indicate that chorionic villus sampling by a rigid forceps is a reliable and relatively safe method for fetal diagnosis of genetic diseases by deoxyribonucleic acid analysis.  相似文献   
110.
不同发育天数囊胚冻融移植后妊娠结局分析   总被引:2,自引:0,他引:2  
目的比较不同发育天数冻融囊胚移植后的妊娠结局。方法回顾性分析1 176例行冻融囊胚移植患者的临床资料,其中植入前遗传学诊断(preimplantation genetic diagnosis,PGD)周期135例,比较第5日单囊胚移植(single embryo transfer,SET)组、双囊胚移植(double embryo transfer,DET)组与第6日SET组和DET组的妊娠结局。结果同是优质囊胚级别的条件下,第5日DET组的生化妊娠率(56.91%)、临床妊娠率(53.25%)以及多胎妊娠率(1.20%)显著高于其他组(P0.05);第5日DET组与SET组的胚胎着床率无统计学差异(P0.05),但均显著高于第6日DET组和SET组(P0.05);同级别以及PGD周期中第5日和第6日SET组相比较,第5日组的生化妊娠率、胚胎着床率均显著高于第6日组(P0.05)。结论在同是优质囊胚的条件下,第5日SET、DET及经PGD诊断的SET妊娠结局均优于第6日。  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