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   2316篇
  免费   171篇
  国内免费   47篇
耳鼻咽喉   11篇
儿科学   94篇
妇产科学   45篇
基础医学   353篇
口腔科学   55篇
临床医学   199篇
内科学   637篇
皮肤病学   47篇
神经病学   152篇
特种医学   162篇
外科学   289篇
综合类   15篇
预防医学   137篇
眼科学   31篇
药学   138篇
  1篇
中国医学   2篇
肿瘤学   166篇
  2023年   15篇
  2022年   13篇
  2021年   49篇
  2020年   24篇
  2019年   43篇
  2018年   75篇
  2017年   52篇
  2016年   58篇
  2015年   61篇
  2014年   75篇
  2013年   101篇
  2012年   129篇
  2011年   128篇
  2010年   83篇
  2009年   83篇
  2008年   118篇
  2007年   132篇
  2006年   94篇
  2005年   78篇
  2004年   68篇
  2003年   72篇
  2002年   77篇
  2001年   54篇
  2000年   66篇
  1999年   49篇
  1998年   60篇
  1997年   68篇
  1996年   65篇
  1995年   53篇
  1994年   40篇
  1993年   50篇
  1992年   32篇
  1991年   37篇
  1990年   24篇
  1989年   29篇
  1988年   43篇
  1987年   33篇
  1986年   32篇
  1985年   26篇
  1984年   15篇
  1983年   16篇
  1982年   9篇
  1981年   13篇
  1980年   13篇
  1978年   8篇
  1977年   12篇
  1976年   7篇
  1975年   11篇
  1974年   5篇
  1969年   5篇
排序方式: 共有2534条查询结果,搜索用时 15 毫秒
21.
22.
The idiopathic inflammatory bowel diseases (IBDs), consisting of Crohn's disease and ulcerative colitis, are complex genetic disorders involving chronic inflammation of the intestines. Multiple genetic loci have been implicated through genome-wide searches, but refinement of localization sufficient to undertake positional cloning efforts has been problematic. This difficulty can be obviated through identification of ancestrally shared regions in genetic isolates, such as the Chaldean population, a Roman Catholic group from Iraq. We analyzed four multiply affected American Chaldean families with inflammatory bowel disease not known to be related. We observed evidence for linkage and linkage disequilibrium in precisely the same region of chromosome band 1p36 reported previously in an outbred population. Maximal evidence for linkage was observed near D1S1597 by multipoint analysis (MLOD = 3.01, P = 6.1 x 10(-5)). A shared haplotype (D1S507 to D1S1628) was observed over 27 cM between two families. There was homozygous sharing of a 5 cM portion of that haplotype in one family and over a <1 cM region in the second family. Homozygous sharing of this haplotype near D1S2697 and D1S3669 was observed in one individual in a third multiply affected family, with heterozygous sharing in a fourth family. Linkage in outbred families as well as in this genetic isolate indicates that a pathophysiologically crucial IBD susceptibility gene is located in 1p36. These findings provide a unique opportunity to refine the localization and identify a major susceptibility gene for a complex genetic disorder.  相似文献   
23.
24.

Health agencies call for the immediate mobilization of existing interventions in response to numerous child and family mental health concerns that have arisen as result of the COVID-19 pandemic. Answering this call, this pilot study describes the rapid, full-scale change from a primarily clinic-based Parent–Child Interaction Therapy (PCIT) model to a virtual service model (i.e., I-PCIT) in an academic and community-based program in Miami, Florida. First, we describe the virtual service training model our program developed and its implementation with 17 therapists (MAge?=?32.35, 88.2% female, 47.1% Hispanic) to enable our clinic to shift from providing virtual services to a small portion of the families served (29.1%) to all of the families served. Second, we examine the effect of I-PCIT on child and caregiver outcomes during the 2-month stay-at-home period between March 16, 2020, and May 16, 2020, in 86 families (MChildAge?=?4.75, 71% Hispanic). Due to the rapid nature of the current study, all active participants were transferred to virtual services, and therefore there was no comparison or control group, and outcomes represent the most recently available scores and not treatment completion. Results reveal that I-PCIT reduced child externalizing and internalizing problems and caregiver stress, and increased parenting skills and child compliance with medium to large effects even in the midst of the COVID-19 pandemic. Finally, the study examined components of our virtual service training model associated with the greatest improvements in child and caregiver outcomes. Preliminary findings revealed that locally and collaboratively developed strategies (e.g., online communities of practice, training videos and guides) had the strongest association with child and caregiver outcomes. Implications for virtual service delivery, implementation, and practice in the midst of the COVID-19 pandemic are discussed.

  相似文献   
25.
Objective To detect new mutations among 29 glucose-6-phosphate dehydrogenase (G6PD) deficient individuals from Yunnan province. Methods The nitroblue tetrazolium (NBT) method was used to screen G6PD deficient individuals. Mutation was identified by single strand conformation polymorphism (SSCP), amplification created restriction site (ACRS), amplification refractory mutation system (ARMS) and DNA sequencing. Results Among 29 cases, 18 cases of G1388A, 1 case of C1004A, and 1 case of G1381A were identified. Nine cases remained to be defined. The G1381A mutation is a novel mis-sense mutation, with a substitution of threonine for alanine (A461T). The resultant G6PD had reduced enzymatic activity. In addition, G1381A caused a restriction site of Stu I to disappear, providing a rapid method for the detection of this mutation. Conclusion A novel mis-sense mutation G1381A was found. This mutation results in a substitution of threonine for alanine, producing enzyme with reduced activity. The loss of the Stu I restriction site offers a rapid method for the detection of this mutation.  相似文献   
26.
In approximately 25-40% of infants presenting with posterior urethral valves (PUV) renal insufficiency will develop before adolescence. In some these patients, renal dysplasia, bladder dysfunction and mismanagement may precipitate renal failure at even earlier age. The goals of this study were to determine whether long-term bladder dysfunction was more frequent in children who underwent early temporary pyelostomy than in those who underwent valve ablation, and to know if bladder dysfunction and mismanagement, in some patients, could be responsible of early renal failure. Urodynamic studies were performed in 59 boys with severe PUV divided into two groups based on initial treatment. A) Valve ablation (30 p.); B) Cutaneous pyeloureterostomy (29 p.). At the end of the study 22 boys had chronic renal failure. Of the 59 boys, 42% (25 p.) had bladders with overdistended or normal behaviour, 58% (34 p.) had bladder dysfunction (instability 37%, low compliance 15%, myogenic failure 5%). The 89% of low compliance bladders, 66% of myogenic failure and 23% of those with instability were in CRF. No difference at all was found in bladder function between boys treated as neonates by high diversion or valve ablation. Of the group in chronic renal failure (22 p.), only 7 patients (32%) had bladders with normal behaviour and in five of these patients a mismanagement was directly related with a quicker renal deterioration. The 58% of our boys with severe PUV have some type of bladder dysfunction. Neonatal pyelo-ureterostomy does not increase long-term bladder dysfunction. Surgical mismanagement should be added to bladder dysfunction as contributors to earlier renal failure.  相似文献   
27.
The neuroactive peptide endothelin-1 has receptors distributed abundantly among subdivisions and nuclei of the visuovestibular and oculomotor systems. In previous work, we and others described the convulsive manifestations resulting from central injection of this neuropeptide, including nystagmus, oculoclonus, exophthalmos, tonic hindlimb extension, and a generalized repetitive motor disturbance called barrel-rolling. We applied the quantitative, autoradiographic [14C]deoxy-glucose method to examine the hypothesis that visuovestibular and oculomotor structures would become metabolically stimulated when endothelin was introduced into the brain via the ventricular system in conscious rats. Since previous work had demonstrated that hypermetabolic responses to endothelin in other neural systems were inhibited by an antagonist of neuronal calcium L-type channels, nimodipine, we further tested whether the increased function of vestibulooculomotor nuclei whose metabolic activity was sensitive to endothelin could be altered following nimodipine pretreatment via the ventricle. A single unilateral injection of endothelin (9 pmol in 3 l saline) into a lateral ventricle provoked significantly increased rates of glucose metabolism in 22 of 39 individual anatomical structures of the visuovestibular and oculomotor systems. Among those affected were the superficial stratum of the caudal superior colliculus (+25%), the optic tract bilaterally (+ 35 to 43%), the oculomotor cranial nerve nuclei (III, IV, VI; range of +21 to 47%), and the medial terminal nucleus of the accessory optic tract which harbors dense fields of endothelin binding sites (bilateral increase of +70 to 96%). Several other nuclei involved in the proprioceptive and visuovestibular disturbance caused by endothelin displayed increased metabolic activity, including the cuneate, gracile, sensory trigeminal, and prepositus hypoglossal nuclei, the vestibular subnuclear system, and the cerebellar flocculus. Identification of hypermetabolic responsivity to endothelin in these structures provides further information on the anatomical substrates mediating the behavioral phenomenology of endothelin-induced motor convulsions which involve the paroxysmal participation of the extraocular muscles and motor control systems producing barrel-rolling convulsions. Nimodipine pretreatment inhibited both the convulsive activity and the cerebral hypermetabolic responses to intraventricular endothelin. The results indicate that the neural systems sensitive to intraventricular endothelin become functionally active via a calcium-mediated process that may involve the neuropeptide as an intrinsic signaling molecule.  相似文献   
28.
Contribution of a retrospective series of 16 patients with type II absorptive hypercalciuria over a total of 1.041 patients undergoing metabolic study due to relapsing renal lithiasis. Clinical history of lithiasis, biochemistry prior to treatment and instituted therapy were examined in all cases. Stones composition, radiologic appearance of lithiasis and evolution of biochemical parameters after medical treatment with a mixture of phosphates were also studied.  相似文献   
29.
30.
Contribution of a case report of cutaneous horn of penis surgically treated with extensive resection of the implantation base. A well differentiated, microinvasive epidermoid carcinoma was histopathologically demonstrated on a hyperkeratosis squamous papilloma. Although underlying lesions to cutaneous horn are usually benign, malignant changes have been reported in up to one third of cases; surgical treatment should therefore include extensive resection of the implantation base.  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