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   14590篇
  免费   877篇
  国内免费   71篇
耳鼻咽喉   71篇
儿科学   547篇
妇产科学   348篇
基础医学   2039篇
口腔科学   254篇
临床医学   1431篇
内科学   3109篇
皮肤病学   367篇
神经病学   1466篇
特种医学   311篇
外科学   1497篇
综合类   85篇
一般理论   16篇
预防医学   1201篇
眼科学   297篇
药学   971篇
中国医学   25篇
肿瘤学   1503篇
  2024年   19篇
  2023年   161篇
  2022年   277篇
  2021年   506篇
  2020年   307篇
  2019年   430篇
  2018年   472篇
  2017年   379篇
  2016年   379篇
  2015年   471篇
  2014年   616篇
  2013年   795篇
  2012年   1235篇
  2011年   1160篇
  2010年   690篇
  2009年   582篇
  2008年   987篇
  2007年   993篇
  2006年   945篇
  2005年   862篇
  2004年   829篇
  2003年   768篇
  2002年   617篇
  2001年   71篇
  2000年   61篇
  1999年   93篇
  1998年   110篇
  1997年   95篇
  1996年   85篇
  1995年   64篇
  1994年   52篇
  1993年   59篇
  1992年   46篇
  1991年   37篇
  1990年   20篇
  1989年   22篇
  1988年   22篇
  1987年   21篇
  1986年   17篇
  1985年   25篇
  1984年   23篇
  1983年   18篇
  1982年   17篇
  1981年   10篇
  1980年   15篇
  1979年   11篇
  1978年   9篇
  1977年   9篇
  1972年   7篇
  1971年   5篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
We studied 31 T1 N0 M0 peripheral adenocarcinomas diagnosed by wedge resection and treated by lobectomy. Factors recorded were pleural surface-based, gross cut-surface, and microscopic margin distances; morphologic features of the adenocarcinomas; microscopic extension distance of beyond gross perimeter of neoplasm; and presence of residual adenocarcinoma in the lobectomy specimen. All staple-line margins in the wedge and lobectomy specimens underwent complete histologic examination. The mean pleural surface-based, gross cut-surface, and microscopic margin distances in wedge resections were 13.1, 4.1, and 2.3 mm, respectively. The mean microscopic wedge resection margin distance was 11 mm smaller than the pleural surface-based measured margin. The mean microscopic lepidic growth beyond the gross perimeter of the neoplasm was 7.4 mm. Fourteen lobectomy specimens (45%) included adenocarcinoma. The mean microscopic wedge resection specimen margin distances in cases with and without residual adenocarcinoma in the lobectomy specimens were 0.7 and 2.4 mm, respectively (P < .001). Incomplete excision may contribute to higher locoregional recurrence rates following limited resection surgery. Two processes affected wedge resection margin distances: stapling-induced parenchymal stretching, resulting in overestimation of pleural surface-based distances, and microscopic extension of adenocarcinoma beyond the gross perimeter of the neoplasm.  相似文献   
992.
A longitudinal study of Ig V gene segments utilized by B cells from the cerebrospinal fluid (CSF) of two patients with multiple sclerosis (MS) was carried out using RT-PCR methodologies. One patient with a relapsing-remitting (RR)-MS was investigated at onset and at relapse, 1 year later. A patient with secondary-progressive (SP)-MS was tested 9 and 13 years after disease onset. Sequence analyses of V(H)DJ(H) segments bearing V(H)3 and V(H)4 that were obtained from Cgamma cDNA genes demonstrated a substantial proportion of shared clones in the samples taken at different times; these clones were identical or closely related, i.e. had the same third complementary determining region (CDR) of the H chain variable region gene (HCDR3) with different mutations in the V(H) segment. Collectively, these data demonstrate that in MS patients there is a strong selective pressure, which could be exerted by antigen (or autoantigen) stimulation, for the maintenance and partial diversification of certain V(H)DJ(H) Cgamma sequences.  相似文献   
993.
This paper reports evidence of the existence of multiple and distinct visual memory processes in a memory search task in which a divided field stimulus presentation was used at study (Experiments 1-3) and either a foveal (Experiments 1 and 2) or a lateralized (Experiment 3) stimulus presentation was used at test. These memory processes can be distinguished on the basis of (1) whether or not they are hemispherically organized; and (2) the locus of their underlying brain activity, as evidenced by the scalp distribution of the event-related brain potentials and by the localization of the event-related optical signal that accompany them. These memory effects are discussed in the context of visual form memory.  相似文献   
994.
995.
The present study sought to examine acute effects of alcohol on cognitive processing and performance within the context of two prominent theories of alcohol's effects; namely, that alcohol restricts the focus of attention (e.g. Steele and Josephs, 1990. Journal of Abnormal Psychology, 97, 196-205) and that alcohol impairs response inhibition (e.g. Fillmore and Vogel-Sprott, 1999. Experimental and Clinical Psychopharmacology, 7, 49-55; Fillmore and Vogel-Sprott, 2000. Journal of Studies on Alcohol, 61, 239-246). Forty-five participants were randomly assigned to receive either a placebo level of alcohol (0.04 g/kg), a moderate dose (0.40 g/kg), or a higher dose (0.80 g/kg). Brain electrical activity (ERPs) and behavioral responses (reaction time and accuracy) were measured while participants performed a modified flanker task, in which a target letter was flanked by response-compatible or response-incompatible letters. Analyses of behavioral data showed that alcohol increased response competition in accuracy but not response times, suggesting that alcohol influences response selection more than attentional processes per se. This finding is in-line with predictions derived from the response inhibition model. ERP latency data provided mixed support for both models. ERP amplitude data showed that the high dose of alcohol primarily influenced a mostly frontal negativity in the ERP, present on both correct and incorrect response trials. Differences in self-reported susceptibility to alcohol were most evident in the amplitude of the P3 component. Findings are discussed in terms of the differential effects of acute dose and susceptibility on information processing.  相似文献   
996.
Purified Actinobacillus actinomycetemcomitans serotype b lipopolysaccharide (LPS) was found to be able to bind Fusobacterium nucleatum cells and to inhibit binding of F. nucleatum to A. actinomycetemcomitans serotype b. Sugar binding studies showed that the requirements for binding of A. actinomycetemcomitans serotype b LPS to the F. nucleatum lectin are the presence of a metal divalent ion, an axial free hydroxyl group at position 4, and free equatorial hydroxyl groups at positions 3 and 6 of D-galactose, indicating that the beta-N-acetyl-D-galactosamine in the serotype b LPS trisaccharide repeating unit is the monosaccharide residue recognized by the F. nucleatum lectin. These data strongly suggest that A. actinomycetemcomitans serotype b LPS is one of the receptors responsible for the lactose-inhibitable coaggregation of A. actinomycetemcomitans to fusobacteria.  相似文献   
997.
998.
Paradoxical sleep deprivation (PSD) for 96 h together with cocaine administration elicits genital reflexes (penile erection [PE] and ejaculation [EJ]) in rats. Our objective was to examine genital reflexes after periods of 24, 48, 72, 96, 120, and 144 h of PSD and during a 4-day recovery period in acute cocaine-administered rats. After 24 h of PSD followed by cocaine administration, animals started to display PE and EJ, peaking in the 96th h of PSD, whereas PE and EJ were absent in control animals. The effects of more than 96 h of PSD decrease genital reflexes as observed after 120 and 144 h. Genital reflexes were present in the recovery periods but diminished gradually during the period evaluated. Even short periods of PSD probably cause supersensitivity of dopamine (DA) receptors and exacerbate the effects of cocaine on dopaminergic pathways to induce frequent PE and EJ.  相似文献   
999.
Abdominal compartment syndrome in children: CT findings   总被引:17,自引:0,他引:17  
Abdominal compartment syndrome (ACS) is caused by pathological elevation of intra-abdominal pressure (IAP) leading to multiple organ dysfunction syndrome. Since the condition is highly lethal, early diagnosis is imperative. We evaluated the pre-operative abdominal CT scans of three children with proven ACS to identify signs of elevated IAP. Findings common to these patients included narrowing of the inferior vena cava (IVC), direct renal compression or displacement, bowel wall thickening with enhancement and a rounded appearance of the abdomen. The aim of recognising the CT findings in such cases is to plan emergency surgical decompression. Although these findings are not specific for increased IAP, radiologists should be aware of this life-threatening condition and, in the proper clinical setting, should communicate the presence and significance of these findings to the referring clinician.  相似文献   
1000.
Chan MS  Wong YC  Lau SP  Lau KY  Ou Y 《Pediatric radiology》2002,32(5):376-379
We present the CT and MRI findings of an 8-day-old infant with an infected cephalhaematoma complicated by skull osteomyelitis, venous sinus thrombosis and left cerebellar haemorrhage.  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