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   4890篇
  免费   283篇
  国内免费   104篇
耳鼻咽喉   37篇
儿科学   248篇
妇产科学   102篇
基础医学   603篇
口腔科学   159篇
临床医学   414篇
内科学   741篇
皮肤病学   20篇
神经病学   267篇
特种医学   377篇
外科学   686篇
综合类   463篇
预防医学   474篇
眼科学   177篇
药学   289篇
  3篇
中国医学   91篇
肿瘤学   126篇
  2024年   5篇
  2023年   108篇
  2022年   210篇
  2021年   282篇
  2020年   224篇
  2019年   254篇
  2018年   239篇
  2017年   181篇
  2016年   179篇
  2015年   162篇
  2014年   319篇
  2013年   330篇
  2012年   239篇
  2011年   272篇
  2010年   183篇
  2009年   222篇
  2008年   233篇
  2007年   240篇
  2006年   192篇
  2005年   160篇
  2004年   141篇
  2003年   91篇
  2002年   70篇
  2001年   90篇
  2000年   76篇
  1999年   67篇
  1998年   60篇
  1997年   53篇
  1996年   44篇
  1995年   45篇
  1994年   22篇
  1993年   20篇
  1992年   25篇
  1991年   16篇
  1990年   17篇
  1989年   19篇
  1988年   17篇
  1987年   16篇
  1986年   15篇
  1985年   14篇
  1984年   20篇
  1983年   14篇
  1982年   18篇
  1981年   21篇
  1980年   15篇
  1979年   5篇
  1978年   8篇
  1977年   7篇
  1974年   5篇
  1973年   5篇
排序方式: 共有5277条查询结果,搜索用时 703 毫秒
61.
红外线短波紫外线照射对感染伤口愈合的影响   总被引:1,自引:0,他引:1  
张卓军 《河北医学》2000,6(10):877-878
目的:探讨红外线、短波紫外线照射对感染性伤口愈合的影响。方法:用随机方法将72例感染伤口病人分为A、B两组,每组36例,A为治疗组:在消炎、伤口换药基础上加用红外线、短波紫外线照射伤口7天,B为对照组:单纯消炎、伤口换药。结果:A组治愈28例,显效8例,有效率100%。B组治愈14例,显效12例,无效10例,有效率72%,统计学处理X^2=15.47P〈0.01,两组有显著差异。结论:红外线、短波  相似文献   
62.
The effects of a series of benzodiazepine (BZ) receptor ligands, ranging from a full agonist through to partial inverse agonists, were examined on short term working memory in the rat. The behavioural paradigm used was a discrete trial, operant delayed matching to position task, as originally described by Dunnett (1985), with delays of 0, 5, 15 and 30 s. The benzodiazepine receptor (BZR) full agonist lorazepam (0.25, 0.375 and 0.5 mg/kg) dose and delay dependently impaired matching accuracy. Lorazepam also increased the latency to respond and decreased the number of nose pokes made into the food tray during the delays. In contrast, the BZR partial agonist ZK 95 962 (1, 3, 10 mg/kg) did not affect matching accuracy, but did increase the speed of responding. The BZR antagonist ZK 93 426 (1.25, 5, 25 mg/kg) had no effects in this paradigm. The BZR weak partial inverse agonists Ro 15-4513 (0.1, 1 and 10 mg/kg) and ZK 90 886 (1, 3 and 10 mg/kg) did not affect accuracy of performance. However, both of these drugs increased the latency to respond and decreased nose poke responses. These motoric effects were particularly strong following 10 mg/kg Ro 15-4513. This shows that the effects of drugs on the accuracy of responding and on the speed of responding can be dissociated. The BZR partial inverse agonist FG 7142 had effects on matching accuracy that were dependent upon dose. The lowest dose of FG 7142 (1 mg/kg) significantly improved accuracy, whereas the highest dose (10 mg/kg) impaired accuracy. This impairment induced by FG 7142 (10 mg/kg) was accompanied by an increase in the latency to respond and a decrease in the number of nose pokes. Taken together, these results show that the accuracy of delayed matching performance can be modulated in opposite ways by the BZR full agonist lorazepam and a low dose of the BZR partial inverse agonist, FG 7142.  相似文献   
63.
The short tandem repeat system FES/FPS was amplified by the polymerase chain reaction (PCR) in 211 unrelated Austrians and analysed by horizontal, non-denaturing electrophoresis. The allele distribution was in Hardy-Weinberg equilibrium. No mutations were found in 25 families (50 meioses). The mean exclusion chance was 0.49, the discriminating power 0.86 and the heterozygosity rate 74.4%. Amplification could be achieved with as little as 100 pg of high molecular weight DNA, which could be reduced to 75 pg by using 32 instead of 30 cycles. By reamplifying 1 l for another 15 cycles, the threshold could be reduced to less than 20 pg. In a degradation experiment DNA extracted from bloodstains stored for up to 24 days in a moist chamber and DNA boiled for up to 18 min could be amplified.  相似文献   
64.
The 5 tetranucleotide short tandem repeats, HUMTHOI, HUMVWA31/A, HUMF13A1, HUMFES/FPS and HUMLPL were studied using different electrophoretic methods and PCR amplification conditions in order to optimize the typing conditions. A genetic population study in the population of Galicia was carried out and the allele and genotype frequencies are given. Compliance with the Hardy-Weinberg equilibrium was tested using different statistical parameters, with clear advantages resulting in favor of using the exact test (Guo-Thompson method) instead of conventional chi-square methods. Some statistical parameters of forensic interest (PD, CE, h) were also calculated. There were no mutations found in a total of 73 paternal meioses and 101 maternal meioses. Abnormal electrophoretic mobility was found in the AT-rich STR HUMF13AI under non-denaturing conditions and, therefore, the use of denaturing conditions is absolutely necessary. No "stutter" bands were found, although double peaks in the HUMFES/FPS system were observed in some samples. The advantage of using automated sequencers with fluorescent technology is also reported.  相似文献   
65.
The gravity model, a method for analyzing transportation distribution in transportation engineering, was used to explain patient trips between ten health service regions in a Japanese prefecture. The OD (Origin-Destination) tables were constructed with zoning by regions, distinguishing between out- and inpatients. The observed trips were determined from the data of a survey conducted in 1992 that reported the locations of patient residences and chosen medical facilities. The base values used in the model calculations were the population size of each region and the road distance between the centers of regions. Problems of intrazonal trip were avoided by setting a mean intrazonal movement distance. This model was calibrated by the linear regression method with simultaneous validation by the index of correlation coefficients. The model was found to accurately simulate the effect of distance on the choice of medical facilities and the differences between the characteristics of in- and out-patients. The population value in use showed the relation not only with demand but also the supply of clinical services. It was suggested that the model presented here was useful in the allocation of medical resources and would help explain the relationship between suppliers and consumers of medical services.  相似文献   
66.
Abstract A short tandem repeat (STR) system consisting of seven multiplexed loci has recently been introduced in the UK to support a National strategy to create large DNA databases for criminal intelligence purposes. The process uses automated sequencers, employing dye-labelled primers. Identification of tetrameric loci such as HUMTH01 are straightforward. Sizing windows are estimated by running a series of control allelic ladders on several gels and unknown samples are designated if they fall within a defined window. However, utilisation of complex STRs (eg. D21 S 11) characteristically have common variants which differ by just 2 bp. In addition, rare alleles are encountered which may differ by just 1 by from a common variant. To assist with the identification of alleles, we have introduced a series of allelic ladders, so that direct comparisons with unknown samples can be made on the same gel. To designate an allele, it should be within 0.5 by of an allelic ladder marker. Not all alleles (in particular rare alleles) can be included within an allelic ladder, however their expected positions can be easily calculated by reference to existing alleles in the ladder. Measurement of band shift is also a useful diagnostic tool. A series of guidelines are described to enable reliable allelic identification. These guidelines can be converted into computer programmes, which form the basis of an expert system.  相似文献   
67.
A case showing many of the typical visceral features of cloacal exstrophy is reported. The patient had fn imperforate anus, a cecal-cloacal fistula, dehiscence of the pubiic symphysis, and lumbosacral spina bifida with synsingomyelia, but the lower abdominal wall was intact without any visceral extroversion. The pertinent literature was reviewed, and it was found that this case corresponded to t typical case of completely covered cloacal exstrophy. Only six cases, including the present one, have so far been reported in the literature. From a clinical viewpoint, it apparently occupies an intermediate position in the wide spectrum of cloacal anomalies between classical cloacal exstrophy and imperforate anus with recto-cloacal fistula, but anatomatically and embryologically it is definitely a variant of cloacal exstrophy. In other words, it looks like an imperforate anus with recto-cloacal exstrophy, but should be treated as a variant of loacal exstrophy. The anatomy, classification, embryology, diagnosis, and management of this peculiar surgical condition are discussed, and recognition of this entity is urged.  相似文献   
68.
对于高位隐睾不能Ⅰ期手术降入阴囊者采用了“长袢输精管”固定术,共治疗12例17侧隐睾,16侧效果满意。随访中对睾丸部位、大小、弹性作了估价。认为手术成功的关键在于高位切断精索、保留输精管血管及睾丸引带侧支。  相似文献   
69.
目的 研究中国汉族人群10个遗传性聋基因座位的短串连重复序列(STR)的遗传多态性。方法 应用PCR方法对10个位点进行扩增,变性聚丙烯酰胺凝胶电泳分离,记录基因型。采用PPAP软件计算正常人各STR位点等位片段频率、基因型频率、预期基因型频率、多态信息量(PIC)和Hardy-Weinberg平衡吻合性检验。结果 中国汉族人群D6S287、D8S1132、D13S1275、D15S130、D1S2726、D4S3038、D2S2380、D22S282、D14S1042、D7S529各位点分别检出10个、9个、8个、7个、7个、7个、6个、6个、6个及5个等位片段,多态性分布均符合Hardy-Weinberg平衡定律。各位点PIC值分别为0.879、0.854、0.864、0.821、0.686、0.794、0.764、0.732、0.773、0.712;杂合度均高于0.7。结论 中国汉族人群10个位点STR均具有较高的杂合度和多态信息量,是较理想的遗传标记。  相似文献   
70.
目的:筛查海洛因依赖者在第19、20、21和22号染色体上的易感基因的位点.方法:对10例海洛因依赖者和其正常同胞对照者的第19、20、21和22号染色体进行以短串联重复序列(short tandem repeats,STR)为遗传标记的基因扫描分析.结果:D20S195和D22S423位点的等位基因在海洛因依赖组和其正常同胞对照组之间分布有显著性差异(P<0.05),其它STR位点的等位基因在海洛因依赖组和其正常同胞对照组之间分布没有显著性差异(P>0.05).结论:D20S195和D22S423位点附近可能存在海洛因依赖的易感基因.  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