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   479篇
  免费   35篇
  国内免费   5篇
耳鼻咽喉   3篇
儿科学   25篇
妇产科学   3篇
基础医学   55篇
口腔科学   30篇
临床医学   46篇
内科学   79篇
皮肤病学   5篇
神经病学   106篇
特种医学   61篇
外科学   30篇
综合类   28篇
预防医学   17篇
眼科学   1篇
药学   7篇
中国医学   4篇
肿瘤学   19篇
  2023年   3篇
  2022年   1篇
  2021年   10篇
  2020年   3篇
  2019年   4篇
  2018年   5篇
  2017年   6篇
  2016年   7篇
  2015年   10篇
  2014年   8篇
  2013年   19篇
  2012年   22篇
  2011年   24篇
  2010年   31篇
  2009年   14篇
  2008年   15篇
  2007年   16篇
  2006年   22篇
  2005年   20篇
  2004年   8篇
  2003年   9篇
  2002年   5篇
  2001年   12篇
  2000年   14篇
  1999年   13篇
  1998年   25篇
  1997年   16篇
  1996年   19篇
  1995年   8篇
  1994年   14篇
  1993年   11篇
  1992年   4篇
  1991年   9篇
  1990年   9篇
  1989年   13篇
  1988年   14篇
  1987年   16篇
  1986年   12篇
  1985年   6篇
  1984年   6篇
  1983年   4篇
  1982年   9篇
  1981年   2篇
  1980年   5篇
  1979年   1篇
  1978年   1篇
  1977年   3篇
  1976年   7篇
  1975年   2篇
  1971年   2篇
排序方式: 共有519条查询结果,搜索用时 31 毫秒
1.
Introduction: This study investigated variables associated with subjective decline in executive function among Veterans of Operations Enduring Freedom, Iraqi Freedom, and New Dawn (OEF/OIF/OND) following a history of blast-related mild traumatic brain injury (mTBI).

Method: Fifty-six male U.S. Veterans (MAge = 35.3 ± 8.8 years) with a history of blast-related mTBI (6.6 ± 3.2 years post injury) completed a battery of self-report questionnaires and neuropsychological measures. Participants rated current and retrospectively estimated pre-mTBI executive function difficulties on the Frontal Systems Behavior Scale (FrSBe). A difference score (post- minus pre-mTBI ratings) was the dependent variable (?FrSBe). Linear regression models examined variables predicting ?FrSBe, including: pre-injury characteristics (education, premorbid intelligence), injury-related characteristics (number of blast exposures, losses of consciousness), post-injury clinical symptoms (PTSD Checklist–Military version; Pittsburgh Sleep Quality Index), and post-injury neuropsychological performances on executive function measures (Trail Making Test Part B; Controlled Oral Word Association Test; Auditory Consonant Trigrams; Wisconsin Card Sorting Test).

Results: While 11% of participants had a clinically elevated pre-injury FrSBe total score, 82% had a clinically elevated post-injury FrSBe total score. Only self-reported PTSD symptom severity independently predicted perceived change in executive function.

Conclusions: Many OEF/OIF/OND Veterans with a history of blast-related mTBI experience subjective decline in executive function following injury. Perceived executive function decline was associated with higher PTSD symptom severity, aligning with previous research associating PTSD with cognitive complaints. Results did not support a correspondence between perceived cognitive change and neuropsychological performances.  相似文献   
2.
Summary A total of 16 patients with recurrent epithelial ovarian cancer were treated with sulofenur (LY 186641), a novel oral sulfonylurea. All subjects had received previous chemotherapy. Anaemia occurred in all 16 patients, 14 of whom required a blood transfusion, and 2/16 patients received methylene blue for breathlessness due to methaemaglobinaemia. Treatment was discontinued in 2/16 cases due to rising liver enzyme values, which reverted to normal on cessation of the drug. There was no nausea or alopecia. Only two minor responses were seen. Plasma drug levels were insufficient to result in antitumour activity as extrapolated from animal data. Further studies that attempt to increase the bioavailability and improve the therapeutic index are warranted.  相似文献   
3.
To evaluate the alpha 2-noradrenergic regulation of arginine vasopressin (AVP) and oxytocin (OT) in normal humans, we measured the effect of the alpha 2-agonist clonidine on concentrations of these neuropeptides in both plasma and cerebrospinal fluid (CSF). Subjects underwent two lumbar puncture studies, one of which was performed 100 min after oral administration of 5 micrograms/kg clonidine. Plasma AVP and OT were measured at a single time point 10 min before lumbar puncture. Both plasma and CSF AVP were significantly lower in the clonidine condition than in the control (no drug) condition. Neither plasma nor CSF OT differed significantly between conditions. Our data confirm previous reports of alpha 2-noradrenergic inhibition of neurohypophyseal release of AVP into blood, and extend these findings to healthy human subjects. Our data also suggest that AVP appearance in CSF, presumably from extraneurohypophyseal vasopressinergic neurons, is regulated by an inhibitory alpha 2-noradrenergic mechanism.  相似文献   
4.
Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system. While its etiology is not well understood, genetic factors are clearly involved. Until recently, most genetic studies in MS have been association studies using the case-control design testing specific candidate genes and studying only sporadic cases. The only consistently replicated finding has been an association with the HLA-DR2 allele within the major histocompatibility complex (MHC) on chromosome 6. Using the genetic linkage design, however, evidence for and against linkage of the MHC to MS has been found, fostering suggestions that sporadic and familial MS have different etiologies. Most recently, two of four genomic screens demonstrated linkage to the MHC, although specific allelic associations were not tested. Here, a dataset of 98 multiplex families was studied to test for an association to the HLA-DR2 allele in familial MS and to determine if genetic linkage to the MHC was due solely to such an association. Three highly polymorphic markers (HLA-DR, D6S273 and TNFbeta) in the MHC demonstrated strong genetic linkage (parametric lod scores of 4.60, 2.20 and 1.24, respectively) and a specific association with the HLA-DR2 allele was confirmed (TDT; P < 0.001). Stratifying the results by HLA-DR2 status showed that the linkage results were limited to families segregating HLA-DR2 alleles. These results demonstrate that genetic linkage to the MHC can be explained by the HLA-DR2 allelic association. They also indicate that sporadic and familial MS share a common genetic susceptibility. In addition, preliminary calculations suggest that the MHC explains between 17 and 62% of the genetic etiology of MS. This heterogeneity is also supported by the minority of families showing no linkage or association with loci within the MHC.   相似文献   
5.
6.
The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403 amino acid dual specificity phosphatase (protein tyrosine phosphatase; PTPase), was shown recently to play a broad role in human malignancy. Somatic PTEN deletions and mutations were observed in sporadic breast, brain, prostate and kidney cancer cell lines and in several primary tumours such as endometrial carcinomas, malignant melanoma and thyroid tumours. In addition, PTEN was identified as the susceptibility gene for two hamartoma syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD families and seven BZS families was screened for germline PTEN mutations. PTEN mutations were identified in 30 of 37 (81%) CD families, including missense and nonsense point mutations, deletions, insertions, a deletion/insertion and splice site mutations. These mutations were scattered over the entire length of PTEN , with the exception of the first, fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD mutations identified in this exon. Seven of 30 (23%) were within the core motif, the majority (five of seven) of which were missense mutations, possibly pointing to the functional significance of this region. Germline PTEN mutations were identified in four of seven (57%) BZS families studied. Interestingly, none of these mutations was observed in the PTPase core motif. It is also worthy of note that a single nonsense point mutation, R233X, was observed in the germline DNA from two unrelated CD families and one BZS family. Genotype-phenotype studies were not performed on this small group of BZS families. However, genotype-phenotype analysis inthe group of CD families revealed two possible associations worthy of follow-up in independent analyses. The first was an association noted in the group of CD families with breast disease. A correlation was observed between the presence/absence of a PTEN mutation and the type of breast involvement (unaffected versus benign versus malignant). Specifically and more directly, an association was also observed between the presence of a PTEN mutation and malignant breast disease. Secondly, there appeared to be an interdependent association between mutations upstream and within the PTPase core motif, the core motif containing the majority of missense mutations, and the involvement of all major organ systems (central nervous system, thyroid, breast, skin and gastrointestinal tract). However, these observations would need to be confirmed by studying a larger number of CD families.   相似文献   
7.
苗淑杰  孙小容  尔凤君 《中国药房》2005,16(20):1579-1580
目的:建立以高效液相色谱法测定小儿磨积片中橙皮苷含量的方法。方法:色谱柱为SpherisorbC18,流动相为甲醇-冰醋酸-水(25∶4∶71),检测波长为283nm,流速为2·0ml/min,柱温为50℃,灵敏度为0·16AUFS,进样量为20μl。结果:橙皮苷进样量在0·024μg~1·2μg范围内与峰面积积分值呈良好的线性关系(r=0·9999),平均回收率为99·1%(RSD=0·8%)。结论:本方法简便、快捷,灵敏度及准确度高,可为小儿磨积片质量控制提供依据。  相似文献   
8.
Gilbert  HS; Praloran  V; Stanley  ER 《Blood》1989,74(4):1231-1234
Myeloproliferative disease (MPD) is heterogeneous in phenotypic expression and may display features consistent with expansion and activation of the monocyte/macrophage population during its course. The role of colony-stimulating factor-1 (CSF-1) in the pathophysiology of MPD was investigated by measuring circulating CSF-1 levels and examining their relationship to disease phenotype. Serum CSF-1 concentrations, measured by radioimmunoassay, were elevated in all MPD phenotypes. CSF-1 levels differed significantly between groups of patients with essential thrombocythemia, polycythemia vera, and postpolycythemic or agnogenic myeloid metaplasia (in ascending order). CSF-1 serum levels were positively correlated with spleen size and the degree of peripheral bone marrow extension, determined by scintigraphy using a macrophage-seeking isotope. There was no correlation between CSF-1 concentration and circulating levels of erythrocytes, neutrophils or platelets, or the presence of bone marrow fibrosis. Elevated serum CSF-1 levels appear to be associated with an expanded monocyte/macrophage population in MPD. In view of the known cooperativity between CSF-1 and other growth factors in regulating hematopoiesis, the finding of increased serum CSF-1 concentrations and its association with myeloid metaplasia and bone marrow extension may indicate a pathophysiologic role for CSF-1 in determining the phenotypic expression of MPD.  相似文献   
9.
目的分析动态监测重型颅脑损伤术后患者血清降钙素原(PCT)、可溶性髓样细胞表达的激发受体-1(sTREM-1)及C反应蛋白与白蛋白比值(CRP/ALB)的变化对肺部感染的早期预测价值。方法选取手术治疗的196例重型颅脑损伤患者,监测并记录术后1、3、5 d的血清PCT、CRP、ALB、sTREM-1及CRP/ALB水平,记录患者术后肺部感染情况。分析重型颅脑损伤术后肺部感染的危险因素,通过绘制受试者工作特征(ROC)曲线分析相关指标对肺部感染的早期预测价值。结果重型颅脑损伤术后发生肺部感染者76例(38.78%),感染发生时间为术后6~13 d,中位数为7 d。无肺部感染组术后3、5 d血清PCT、sTREM-1及CRP/ALB低于肺部感染组,差异有统计学意义(P0.05);肺部感染组术后5 d血清ALB低于无肺部感染组,差异有统计学意义(P0.05)。机械通气时间、术后格拉斯哥昏迷量表(GCS)评分、术后急性生理与慢性健康评分Ⅱ(APACHEⅡ)以及术后5 d血清PCT、sTREM-1及CRP/ALB是术后肺部感染的独立危险因素(P0.05)。ROC曲线显示,单独检测时,术后5 d血清CRP/ALB预测肺部感染的曲线下面积(AUC)值、约登指数、特异度最高,sTREM-1预测的敏感度最高;联合检测的AUC、约登指数、灵敏度、特异度均高于单独检测。肺部感染诊断时临床肺部感染评分(CPIS)、全身炎症反应综合征修正(ASS)评分均与术后5 d PCT、sTREM-1、CRP/ALB水平呈显著正相关(P0.05)。结论术后5 d血清PCT、sTREM-1及CRP/ALB水平均可作为重型颅脑损伤术后肺部感染早期预测的有效依据,而联合检测的预测价值更高,更有利于早期对肺部感染程度及病情进展的评估。  相似文献   
10.
BACKGROUND: The effects of aging on sympathetic nervous system and adrenomedullary outflow were estimated by the measurement of plasma norepinephrine (NE) and epinephrine (EPI) responses to yohimbine and clonidine in healthy young and healthy older subjects. METHODS: Yohimbine (0.65 mg/kg), clonidine (5 microg/kg), and placebo were administered on separate days in random order to 5 healthy older men (age 74 +/- 1 years) and 18 healthy young men (age 26 +/- 1 years). NE and EPI were measured by radioenzymatic assay in plasma samples obtained before and 30, 60, and 90 minutes after drug administration. RESULTS: Plasma NE increases after yohimbine were greater in older men than in young men. but plasma NE decreases following clonidine did not differ between groups. Plasma NE and systolic blood pressure were higher in older men than in young men at baseline but no longer differed 90 minutes after clonidine. Plasma EPI increases after yohimbine and decreases after clonidine did not differ between groups. CONCLUSIONS: These results suggest increased sympathetic nervous system outflow in human aging that is not a function of reduced responsiveness of alpha-2 adrenoreceptor-mediated feedback inhibition.  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