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   2200篇
  免费   208篇
  国内免费   24篇
耳鼻咽喉   8篇
儿科学   126篇
妇产科学   29篇
基础医学   291篇
口腔科学   31篇
临床医学   178篇
内科学   467篇
皮肤病学   46篇
神经病学   371篇
特种医学   121篇
外科学   209篇
综合类   41篇
预防医学   152篇
眼科学   58篇
药学   97篇
肿瘤学   207篇
  2021年   21篇
  2020年   22篇
  2019年   28篇
  2018年   32篇
  2016年   26篇
  2015年   30篇
  2014年   31篇
  2013年   58篇
  2012年   60篇
  2011年   78篇
  2010年   38篇
  2009年   48篇
  2008年   72篇
  2007年   92篇
  2006年   100篇
  2005年   92篇
  2004年   86篇
  2003年   80篇
  2002年   79篇
  2001年   79篇
  2000年   51篇
  1999年   63篇
  1998年   44篇
  1997年   35篇
  1996年   51篇
  1995年   37篇
  1994年   37篇
  1993年   26篇
  1992年   46篇
  1991年   42篇
  1990年   46篇
  1989年   44篇
  1988年   56篇
  1987年   42篇
  1986年   58篇
  1985年   36篇
  1984年   30篇
  1983年   32篇
  1982年   24篇
  1981年   30篇
  1980年   27篇
  1979年   29篇
  1978年   31篇
  1977年   25篇
  1976年   19篇
  1975年   21篇
  1974年   20篇
  1971年   19篇
  1969年   19篇
  1967年   19篇
排序方式: 共有2432条查询结果,搜索用时 15 毫秒
1.
Summary Cytosine arabinsodie (ara-C) and etoposide (VP-16) display synergy in the laboratory. Twenty-six patients participated in a phase I study of high-dose ara-C in combination with VP-16. The dose of VP-16 was held constant at 50 mg/m2 as an intermittent infusion over 33 h; escalating doses of ara-C were given as infusions during hours 9–12 and 21–24. Myelosuppression was the dose-limiting toxicity and occurred with doses considerably less than those expected from studies of the two drugs as single agents. The suggested initial doses for phase II trials with this schedule are 750 mg/m2×2 doses of ara-C and 50 mg/m2 of VP-16. Nonhematologic toxicity was minimal; therefore, further dose escalation is feasible in patients in whom myelosuppression is acceptable.Supported in part by grants from the National Cancer Institute (CA-12197 and CA-09422) and the American Cancer Society CF-85-182  相似文献   
2.
A quantitative assay for ALZ-50 immunoreactivity was evaluated in samples of superior temporal gyrus taken at autopsy from 13 Alzheimer patients and 11 controls. The assayable immunoreactivity appears to be stable for at least 24 hours postmortem but was lost with formalin fixation. The mean value of the Alzheimer patients was tenfold higher than that of the controls (P less than .002). The values of four Alzheimer samples overlapped with the low levels seen in controls, but no controls had elevated levels. In this sample population, therefore, the assay had a sensitivity of 69% and specificity of 100%.  相似文献   
3.
BACKGROUND: The HOXA1 gene plays a major role in brainstem and cranial morphogenesis. The G allele of the HOXA1 A218G polymorphism has been previously found associated with autism. METHODS: We performed case-control and family-based association analyses, contrasting 127 autistic patients with 174 ethnically matched controls, and assessing for allelic transmission disequilibrium in 189 complete trios. RESULTS: A, and not G, alleles were associated with autism using both case-control (chi(2) = 8.96 and 5.71, 1 df, p <.005 and <.025 for genotypes and alleles, respectively), and family-based (transmission/disequilibrium test chi(2) = 8.80, 1 df, p <.005) association analyses. The head circumference of 31 patients carrying one or two copies of the G allele displayed significantly larger median values (95.0th vs. 82.5th percentile, p <.05) and dramatically reduced interindividual variability (p <.0001), compared with 166 patients carrying the A/A genotype. CONCLUSIONS: The HOXA1 A218G polymorphism explains approximately 5% of the variance in the head circumference of autistic patients and represents to our knowledge the first known gene variant providing sizable contributions to cranial morphology. The disease specificity of this finding is currently being investigated. Nonreplications in genetic linkage/association studies could partly stem from the dyshomogeneous distribution of an endophenotype morphologically defined by cranial circumference.  相似文献   
4.
Pityriasis rosea (PR) is a relatively common disease although its aetiology has not yet been identified. It occurs worldwide and there is no racial susceptibility factor. It usually affects teenagers and young adults between 10 and 35 years of age. Typical PR is much easier to diagnose than the rare atypical forms. We report a rare case of vesicular PR in a black woman who had vesicular lesions limited to her palms and soles in addition to regular typical lesions. We devised an efficient oral erythromycin treatment for this patient.  相似文献   
5.
6.
7.
8.
Two large cohorts of Black 3rd-grade children from low-income families were followed into early adolescence. Adjustment at the end of the 1st year of middle school was assessed by teacher and parent ratings and by adolescent self-reports. Childhood peer social status predicted parent-reported externalized and internalized disorder and self-reported internalized disorder. Childhood aggression predicted self-reported externalized and internalized disorder and parent-reported externalized disorder. Teacher ratings of school adjustment were predicted by aggression, rejection, and sex of the child. Consensus judgments of poor adjustment were predicted by both aggression and peer rejection, with sex moderating the effect of peer rejection. Both childhood aggression and peer rejection appear to be significant predictors of adolescent disorder, with each making a predictive contribution uniquely its own.  相似文献   
9.
The assimilated os sustentaculi is a projection of bone from the medial aspect of the sustentaculum tali which is surmounted by a similar projection from the medial tubercle of the talus. The accessory joint so formed may develop secondary osteoarthritis changes. This congenital anomaly is very rate. The present report is of 2 additional cases.  相似文献   
10.
Rat models of Parkinson's disease typically employ a rapid nigral injection of 6-hydroxydopamine (6-OHDA) to produce a near-complete loss of nigrostriatal dopamine neurons, and thus model end stage disease. The present report describes the use of a continuous, low dose infusion of 6-OHDA into the striatum which produces a terminal axotomy of nigrostriatal dopamine neurons and protracted behavioral response. A solution of 6-OHDA in 0.4% ascorbate, delivered at 37°C from osmotic minipumps, was stable for 8 days as determined by its retained toxicity to a dopaminergic neuroblastoma cell line. The continuous infusion of 0.2 μg 6-OHDA per h did not affect the striatal uptake of [3H]GABA, [3H]choline, or [3H]glutamate but reduced [3H]dopamine uptake by 55% within 1.5 days after the start of the infusion. The striatal infusion of 6-OHDA produced a dose-dependent reduction of striatal dopamine and DOPAC levels but did not alter HVA, 5-HT, or 5-HIAA. An increase in amphetamine-induced ipsiversive rotations occurred within 1.5 days after the acute striatal injection of 20 μg or 30 μg of 6-OHDA but required 4 days to develop with the continuous 6-OHDA infusion. The topography of the lesion mapped by [3H]mazindol binding showed that, begining by 1.5 days, a diffuse depletion of terminals encompassed much of the striatum in the 30 μg acute injection group, whereas in the continuously infused rats, the lesion was apparent only by 4 days and was restricted to a smaller and more completely lesioned area. Unlike acutely lesioned animals, continuously infused rats revealed no obvious loss of dopamine neurons in the pars compacta by 5 weeks after 6-OHDA. The continuous striatal infusion of 6-OHDA can produce a topographically limited terminal axotomy of dopamine neurons and a protracted behavioral impairment.  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