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   7875篇
  免费   590篇
  国内免费   11篇
耳鼻咽喉   109篇
儿科学   276篇
妇产科学   124篇
基础医学   906篇
口腔科学   177篇
临床医学   847篇
内科学   1554篇
皮肤病学   87篇
神经病学   742篇
特种医学   240篇
外国民族医学   1篇
外科学   1529篇
综合类   113篇
一般理论   5篇
预防医学   617篇
眼科学   192篇
药学   542篇
中国医学   18篇
肿瘤学   397篇
  2023年   32篇
  2022年   73篇
  2021年   190篇
  2020年   99篇
  2019年   177篇
  2018年   179篇
  2017年   142篇
  2016年   153篇
  2015年   200篇
  2014年   247篇
  2013年   367篇
  2012年   520篇
  2011年   579篇
  2010年   326篇
  2009年   266篇
  2008年   455篇
  2007年   527篇
  2006年   474篇
  2005年   424篇
  2004年   383篇
  2003年   354篇
  2002年   348篇
  2001年   134篇
  2000年   129篇
  1999年   103篇
  1998年   79篇
  1997年   65篇
  1996年   71篇
  1995年   40篇
  1994年   48篇
  1993年   39篇
  1992年   70篇
  1991年   76篇
  1990年   83篇
  1989年   82篇
  1988年   56篇
  1987年   58篇
  1986年   77篇
  1985年   62篇
  1984年   77篇
  1983年   63篇
  1982年   49篇
  1981年   35篇
  1980年   27篇
  1979年   49篇
  1978年   39篇
  1977年   37篇
  1975年   30篇
  1974年   27篇
  1973年   44篇
排序方式: 共有8476条查询结果,搜索用时 0 毫秒
21.
22.
OBJECTIVE: Casual observation of gluteal region fat thickness on computed tomography (CT) of the pelvis leads to the hypothesis that, in some individuals, intended intramuscular injections are not properly deposited in the gluteal muscle. We gathered and analyzed data to determine whether this hypothesis was true. METHODS: CT scans of the pelvis were analyzed over an 18-day period in the fall of 2005. The thickness of gluteal region subcutaneous fat was measured in a standardized manner. RESULTS: Measurement of gluteal region subcutaneous fat thickness was performed for 298 pelvic CT scans. There were 150 male subjects and 148 female subjects. The average gluteal fat thickness for female subjects was 33.2 mm, whereas the average for male subjects was 23.1 mm. Analysis revealed a significant difference in gluteal region fat thickness between male and female subjects. A 37-mm needle, allowing for 6-mm penetration of the gluteal muscle, would not have entered the gluteal muscle fibres in 81 of 148 female subjects (54.7%), in 21 of 150 male subjects (14%), and in 102 of the 298 total sample (34.2%). Analysis revealed a significant difference between male and female subjects with regard to gluteal muscle needle penetration. CONCLUSION AND RECOMMENDATION: An overall predicted failure rate of 34% was identified for intended gluteal intramuscular injections when the standard technique was used. This is important information for care providers who inject medications in the gluteal region. In a significant number of patients, the medications will be injected subcutaneously and not into the gluteal musculature, possibly altering the pharmacokinetics of the administered medication. An alternative injection site should probably be chosen to increase the success rate of intramuscular deposition of medications and vaccines in unselected adults.  相似文献   
23.
Purpose. This paper compares unsteady-state and steady-state methods for estimating dermal absorption or analyzing dermal absorption data. The unsteady-state method accounts for the larger absorption rates during short exposure times as well as the hydrophilic barrier which the viable epidermis presents to lipophilic chemicals. Methods. Example calculations for dermal absorption from aqueous solutions are presented for five environmentally relevant chemicals with molecular weights between 50 and 410 and log10Kow between 0.91 and 6.8: chloromethane, chloroform, chlordane, 2,3,7,8-TCDD, and dibenz(a,h)anthracene. Also, the new method is used to evaluate experimental procedures and data analyses of in vivo and in vitro permeation measurements. Results. In the five example cases, we show that the steady-state approach significantly underestimated the dermal absorption. Also, calculating permeability values from cumulative absorption data measured for exposure periods less than 18 times the stratum corneum lag time will overestimate the actual permeability. Conclusions. In general, steady-state predictions of dermal absorption will underestimate dermal absorption predictions which consider unsteady-state conditions. Permeability values calculated from data sets which include unsteady-state data will be incorrect. Strategies for analyzing in vitro diffusion cell experiments and confirming steady state are described.  相似文献   
24.
25.
Developmental data were abstracted from medical records on 50 trisomy 18 individuals ranging in age from 1 to 232 months and 12 trisomy 13 individuals ranging in age from 1 to 130 months. Data on the age when trisomy 18 and trisomy 13 children achieved developmental skills were collected from a larger group of 62 trisomy 18 individuals and 14 trisomy 13 individuals whose families filled out parent questionnaires. Developmental quotient (DQ), defined as developmental age divided by chronological age, averaged 0.18 for trisomy 18 and 0.25 for trisomy 13. There was a dramatic drop in DQ from infancy to later childhood. The highest DQs and the greatest variation in DQs were in the first 2–3 years of life. Developmental ages in 7 skill areas were significantly different, with daily living and receptive language having the highest values and motor and communication skills having the lowest. When chronological age was taken into account, there was no significant difference in DQs in the same 7 skill areas, although there was a trend that was similar to the pattern of differences with developmental age. Older children could use a walker, understand words and phrases, use a few words and/or signs, crawl, follow simple commands, recognize and interact with others, and play independently. Walking and some toileting skills were also reported for trisomy 13. Although individuals with trisomy 18 and trisomy 13 were clearly functioning in the severe to profound developmentally handicapped range, they did achieve some psychomotor maturation and always continued to learn. © 1994 Wiley-Liss, Inc.  相似文献   
26.
BACKGROUND: We tested whether transcranial magnetic stimulation (TMS) over the left dorsolateral prefrontal cortex (DLPFC) is effective and safe in the acute treatment of major depression. METHODS: In a double-blind, multisite study, 301 medication-free patients with major depression who had not benefited from prior treatment were randomized to active (n = 155) or sham TMS (n = 146) conditions. Sessions were conducted five times per week with TMS at 10 pulses/sec, 120% of motor threshold, 3000 pulses/session, for 4-6 weeks. Primary outcome was the symptom score change as assessed at week 4 with the Montgomery-Asberg Depression Rating Scale (MADRS). Secondary outcomes included changes on the 17- and 24-item Hamilton Depression Rating Scale (HAMD) and response and remission rates with the MADRS and HAMD. RESULTS: Active TMS was significantly superior to sham TMS on the MADRS at week 4 (with a post hoc correction for inequality in symptom severity between groups at baseline), as well as on the HAMD17 and HAMD24 scales at weeks 4 and 6. Response rates were significantly higher with active TMS on all three scales at weeks 4 and 6. Remission rates were approximately twofold higher with active TMS at week 6 and significant on the MADRS and HAMD24 scales (but not the HAMD17 scale). Active TMS was well tolerated with a low dropout rate for adverse events (4.5%) that were generally mild and limited to transient scalp discomfort or pain. CONCLUSIONS: Transcranial magnetic stimulation was effective in treating major depression with minimal side effects reported. It offers clinicians a novel alternative for the treatment of this disorder.  相似文献   
27.
28.
Orbital trauma may be associated with various visual and ocular motility disturbances. We describe a case of orbital apex syndrome after penetrating orbital trauma.  相似文献   
29.
Abstract: We describe a new case of a rare syndrome characterized by ocular abnormalities and pathognomonic linear skin defects. This syndrome is the result of an unbalanced translocation resulting in a deletion of the distal end of the short arm of the X chromosome. We report the thirteenth case and review the clinical and cytogenetic aspects of this disorder. In addition we discuss new findings pertaining to the histopathology of the skin lesions.  相似文献   
30.
Milk and orange juice (OJ) fortified with calcium-citrate-malate (CCM; calcium-citrate-malate salt is a coined term to describe a trademarked calcium delivery system found only in Citrus Hill Plus Calcium) were evaluated for their potential to alter urine chemistries and crystallization during the course of an eleven week, crossover study. Six male and six female, non-stone-forming, idiopathic hypercalciuric adults consumed 600 mg per day as beverage calcium for four consecutive weeks. The results show that both milk and CCM-fortified OJ (CCM-OJ) were well tolerated by male and female hypercalciurics since few significant changes occurred in overall urinary chemistry profiles. CCM-OJ did, however, significantly (P less than or equal to 0.05) increase urinary pH relative to milk in both sexes and urinary citrate concentration in women only. Both of these urinary parameters were significantly increased by CCM-OJ in both sexes relative to the basal period. The combined pH and citrate effects are recognized to protect against calcium oxalate stone formation through formation of the soluble calcium citrate salt. These data indicate that either milk or CCM-fortified orange juice can be consumed, at least within the limits tested, as a dietary source of calcium without increasing the risk of stone formation in a calcium-sensitive subpopulation. That the urine chemistries and crystallization of such calcium-sensitive individuals does not significantly change with the consumption of either beverage implies that the urine of normal individuals would be exceedingly unlikely to change as well.  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