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   8711篇
  免费   784篇
  国内免费   19篇
耳鼻咽喉   74篇
儿科学   249篇
妇产科学   140篇
基础医学   1062篇
口腔科学   179篇
临床医学   1004篇
内科学   2011篇
皮肤病学   117篇
神经病学   917篇
特种医学   366篇
外科学   1097篇
综合类   122篇
一般理论   4篇
预防医学   870篇
眼科学   354篇
药学   586篇
中国医学   4篇
肿瘤学   358篇
  2021年   146篇
  2020年   78篇
  2019年   131篇
  2018年   153篇
  2017年   133篇
  2016年   114篇
  2015年   133篇
  2014年   192篇
  2013年   291篇
  2012年   409篇
  2011年   478篇
  2010年   211篇
  2009年   210篇
  2008年   390篇
  2007年   381篇
  2006年   420篇
  2005年   403篇
  2004年   399篇
  2003年   387篇
  2002年   378篇
  2001年   263篇
  2000年   276篇
  1999年   213篇
  1998年   82篇
  1997年   79篇
  1996年   68篇
  1995年   72篇
  1994年   66篇
  1993年   81篇
  1992年   184篇
  1991年   179篇
  1990年   180篇
  1989年   158篇
  1988年   169篇
  1987年   150篇
  1986年   156篇
  1985年   140篇
  1984年   104篇
  1983年   107篇
  1982年   91篇
  1981年   69篇
  1980年   62篇
  1979年   75篇
  1978年   87篇
  1977年   80篇
  1976年   75篇
  1974年   67篇
  1973年   65篇
  1972年   61篇
  1971年   71篇
排序方式: 共有9514条查询结果,搜索用时 15 毫秒
1.
2.
OBJECTIVE: To determine if there is a diurnal pattern in the clinical symptoms of HELLP (Hemolysis, Elevated Liver enzymes, Low Platelets) syndrome. STUDY DESIGN: A retrospective study was performed in 134 pregnancies complicated by HELLP syndrome. The medical records were reviewed to describe each HELLP episode. Time of day was divided into three periods, day, evening, and night. The following parameters were categorized according to the time of day: onset of symptoms, consultation by the doctor, initial blood sampling, diagnosis and decrease of symptoms. Biochemical parameters at clinical presentation and consecutive changes within 24 h were recorded. RESULTS: In 65 pregnancies 77 HELLP episodes were well documented. Times of onset of symptoms and consultation by the doctor were significantly higher during the evening and night (p < 0.001), whereas times of diagnosis and decrease of symptoms occurred significantly more during the day (p < 0.001). In only 49.3% of the cases were diagnostic laboratory criteria met at clinical presentation. This was mainly due to platelet values in excess of 100 x 10(9)/l. Several hours later (median 8 h, range 2-23) the decrease in platelets occurred. CONCLUSIONS: A diurnal pattern exists in the clinical symptoms of HELLP syndrome that is characterized by an exacerbation during the night and recovery during the day. There is a considerable delay between the onset of symptoms and the fulfillment of diagnostic laboratory criteria.  相似文献   
3.
4.
Despite the widespread use of botulinum toxin to treat muscle dystonias, no method exists to quantify muscle paralysis in either human or nonhuman models. In this study we examined how the location, dose, and volume of botulinum injection affects paralysis in the rat tibialis anterior muscle. Paralysis was quantified by electrically stimulating the nerve to the tibialis anterior and then staining sections of the muscle for glycogen. The areas of glycogen-containing fibers represented regions of botulinum action. The results showed that the most important injection technique is to inject botulinum directly into the motor endplate region of a muscle. Injections only 0.5 cm from the motor endplate resulted in a 50% decrease in paralysis. Increases in dose increased paralysis, however, some of that increase was simply due to the increased volume of injection. Thus, delivering toxin in small volumes near the MEP band of a muscle should produce the most effectiveparalysis. © 1993 John Wiley & Sons, Inc.  相似文献   
5.
Nafarelin controlled release injectable (CRI) releases a decapeptide drug for target one month therapy. Nafarelin, a luteinizing hormone releasing hormone agonistic analogue, is microencapsulated in biodegradable poly(lactide-co-glycolide) microspheres and given by intramuscular injection. Clinical data from a human single dose Phase I clinical study are modelled to develop theoretical multiple dose profiles and theoretical single dose profiles from mixtures of two or three formulations. Single dose injections of nafarelin CRI microspheres (4 mg nafarelin) containing 2, 4, or 7 per cent nafarelin all achieve useful plasma drug levels throughout the target 30 day interval. Therapeutic suppression of testosterone levels was observed in all subjects participating in the phase I clinical study. Highest plasma nafarelin levels are achieved in the 0-10 and 20-35 day post-injection intervals. Theoretical multiple dosing profiles generated from the single dose clinical results show significant oscillations in plasma nafarelin levels depending on the particular dosing interval selected. Thirty or forty day dosing intervals yield significant variability in plasma nafarelin levels at steady state; 15 day dosing intervals show less variability. Therapeutic testosterone suppression was observed in the single dose study, so the nafarelin dose per injection can be reduced in multiple dosing therapies. Theoretical plasma nafarelin profiles from certain mixtures of 2 and 4 per cent nafarelin microspheres or 2 and 7 per cent nafarelin microspheres indicate that a 60 day product could be achieved. In general, all three formulations yield their lowest plasma drug levels during the 10-20 day post-injection interval. Therefore any mixture of these formulations will likewise exhibit low plasma drug levels during this interval.  相似文献   
6.
7.
Fractures of the calcaneus generally occur in the event of high-energy trauma, resulting in complex, three-dimensionally oriented fracture patterns. Surgical management is generally indicated for displaced intra-articular fractures, which allows restoration of calcaneal height, width and overall morphology, in addition to the posterior facet articular surface where possible, and allows for a late in situ arthrodesis as a means of salvage in the event of posttraumatic arthritis. What follows is a brief discussion of our preferred methods in the diagnosis and management of calcaneal fractures.  相似文献   
8.
9.
The electromyographic (EMG) interference pattern (IP) was measured in the biceps muscle of 16 normal male and 17 normal female subjects. The activity, upper centile amplitude (UCA), and the number of small segments (NSS) (defined in a companion paper) were measured from 500-msec epochs of the IP. The normal values of these features were defined separately for men and women by plotting the UCA and NSS values against activity for each epoch and defining an area on these plots, called a “cloud,” that contained more than 90% of the datum points from each study. The mean deviation of the individual datum points from the overall mean values was also calculated for each study. A study in one muscle is considered to be normal if more than 90% of the datum points from that muscle are within the normal clouds and the deviation values are within their normal range. In patients with neuropathy, the characteristic pattern was increased UCA with normal or decreased NSS. In patients with myopathy, NSS was increased and the UCA was normal or decreased. In all studies, the interpretations of the IP from the plots agreed with qualitative assessments of the IP made independently by an electromyographer. The use of these features to understand and quantitate the changes in the motor units produced by disease is demonstrated by serial studies performed in a patient with motor neuron disease.  相似文献   
10.
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