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   747篇
  免费   68篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   16篇
妇产科学   14篇
基础医学   115篇
口腔科学   5篇
临床医学   81篇
内科学   161篇
皮肤病学   23篇
神经病学   92篇
特种医学   17篇
外科学   93篇
综合类   2篇
预防医学   36篇
眼科学   30篇
药学   50篇
中国医学   2篇
肿瘤学   73篇
  2024年   2篇
  2023年   13篇
  2022年   9篇
  2021年   40篇
  2020年   19篇
  2019年   28篇
  2018年   38篇
  2017年   27篇
  2016年   32篇
  2015年   39篇
  2014年   29篇
  2013年   42篇
  2012年   72篇
  2011年   79篇
  2010年   39篇
  2009年   39篇
  2008年   52篇
  2007年   58篇
  2006年   37篇
  2005年   30篇
  2004年   28篇
  2003年   21篇
  2002年   21篇
  2001年   2篇
  2000年   4篇
  1999年   6篇
  1997年   3篇
  1995年   1篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1984年   1篇
排序方式: 共有816条查询结果,搜索用时 546 毫秒
51.
Frequent activating mutations of FGFR3 (fibroblast growth factor receptor 3) are found in human urothelial cell carcinomas, particularly in superficial papillary tumours (in 74%-84% of pTaG1-G2), but not in carcinomas in situ (CIS) and at a low rate in invasive tumours (in 16%-21% of pT1-4). In mice and rats, BBN (N-butyl-N-(4-hydroxybutyl)nitrosamine) specifically induces bladder tumours. In rats, superficial papillary tumours are mostly observed. In mice, tumour progression follows the CIS pathway: CIS are first observed, followed by tumours that invade surrounding muscle. Therefore, we looked for FGFR3 mutations in these two animal models of bladder cancer. Only the FGFR3b isoform is expressed in human urothelium and derived tumours. We identified the FGFR3b isoform in rats for the first time and showed that this is the main isoform expressed in the bladder urothelium and derived carcinomas in mice and rats, as in humans. SSCP and sequence analysis of FGFR3b showed sequence changes (polymorphisms or silent mutations) in four BBN-induced rat and mouse bladder tumours. The absence of activating mutations of FGFR3 in the mouse model was in agreement with the fact that mouse BBN-induced bladder tumour progression mimics the CIS pathway. The absence of FGFR3 mutations in the rat bladder tumours suggests that, at least at the genetic level, rat superficial papillary tumours differ from their human counterparts.  相似文献   
52.
Tonic dystonia is an underrecognized complication of reflex sympathetic dystrophy syndrome (RSDS) characterized by an increase in muscle tone at the site of injury. Case-reports.- We describe five cases of tonic dystonia complicating RSDS of the lower extremity. There were four women and one man, with a mean age of 52 years. In addition to the typical features of RSDS, the patients had fixed equinovarus of the foot with hyperextension or hyperflexion of the great toe. In two patients, examination after spinal anesthesia showed that the deformity was reducible. Spontaneous resolution of the dystonia occurred in one patient. Another patient failed to experience meaningful improvement after a motor block followed by botulinic toxin injections. In two patients, the same treatment was followed by a slight improvement. Treatment options are still being evaluated in the last patient. Discussion.- Tonic dystonia is an underrecognized complication of RSDS that often develops after a minor injury yet causes prolonged pain and disability. Spread of the dystonia to other sites is not infrequent. The underlying mechanisms remain unclear but may involve dysfunction of the central or peripheral nervous system or psychogenic factors. Suggested treatments include motor block, intrathecal baclofen, sympathetic block, and sympathectomy. However, none of these treatments has been proved effective. Conclusion.- The five cases described here provide useful information on RSDS-associated tonic dystonia, a condition that runs a protracted course and remains difficult to manage.  相似文献   
53.
PURPOSE: To characterize novel pharmaceutical organogels based on the self-assembly of L-alanine derivatives in hydrophobic vehicles. METHODS: The gelation properties of N-lauroyl-L-alanine (LA) and N-lauroyl-L-alanine methyl ester (LAM) were investigated in the presence of various solvents. Gel-sol and sol-gel transitions were evaluated by the inverse flow method, and gelation kinetics were determined by turbidimetry. The in vitro release kinetics of labeled dextran physically dispersed in the oil-based organogel was assessed in phosphate-buffered saline. In situ formation of the implants was evaluated in rats by subcutaneously injecting a solution containing LAM, an oil, and a water-diffusible inhibitor of self-assembly (ethanol). RESULTS: The LAM-containing formulations showed a hysteretic gelling behavior with transition temperatures between 10 and 55 degrees C. Gelation kinetics exhibited a lag time of 10 and 30 min at 25 and 37 degrees C, respectively. In vitro, fluorescein isothiocyanate-dextran was released from the gel in a sustained manner with less than 6% released after 20 days. The addition of ethanol to the LAM/oil mixture inhibited gelation and allowed subcutaneous injection of the solution at room temperature. After injection, ethanol diffusion led to the formation of a solid implant. CONCLUSIONS: Low-molecular weight self-assembling organogelators may allow the preparation of novel in situ-forming hydrophobic implants.  相似文献   
54.
OBJECTIVE: To investigate the role of different cellular types (epithelial and stromal endometrial cells and peritoneal cells) in the ectopic implantation of endometrium and to evaluate the importance of endocrine environment on the adhesion of endometrial cells to the peritoneum. DESIGN: Experimental prospective study. SETTING: University hospital, department of cell biology. ANIMAL(S): One hundred one nude mice. INTERVENTION(S): Monolayer culture of human epithelial and stromal endometrial cells obtained from patients undergoing hysterectomy or laparoscopy for benign disease. Intraperitoneal injection of cells into nude mice. MAIN OUTCOME MEASURE(S): Two weeks after cell injection, adhesion of endometrial cells was evaluated by histological and immunohistochemical examination. RESULT(S): Mixed cultures of stromal and epithelial cells, but not purified epithelial or stromal cells alone, adhered to the mouse peritoneum and led to endometriotic-like nodules. Pretreatment of cells with estrogen alone or with estrogen and progestin resulted in a higher percentage of animals developing endometriotic-like nodules, whereas treatment with progestin alone did not affect endometriotic implantation. CONCLUSION(S): Our data indicate that the success of endometrial cell implantation is dependent on the cooperativeness between stromal and epithelial endometrial cells, as well as on the endocrine environment of endometrial cells, but not that of recipient animals. The results emphasize the role of both endometrial cell types for ectopic implantation.  相似文献   
55.
56.
Sulcus vocalis is described as a groove at the free edge of the vocal fold. Different types have been described: sulcus type I is superficial and may be considered as moreless physiologic. Sulcus type IIa corresponds to a kind of vergeture along the margin of the vocal fold. Its deepness is variable but sulcus vergeture may involve deeper layers of the lamina propria. Sulcus type IIb or pounch may be considered as an open cyst. Sulcus lead to a complex glottic dysfunction with, in the same time, a glottal leakage responsible for the breathy component of the dysphonia and a stiffness of the free edge responsible for the roughness. Diagnosis may be difficult even with the help of stroboscopy and finally is sometimes done only under general anesthesia. Etiology remains controversial and the authors present arguments for each theory, acquired or congenital. Treatment options include phonosurgery and speech therapy but phonosurgery gives results often disappointing and surgical treatment must be indicated prudently and patient must be intensively informed on what he or she can expect from the treatment that is mainly an increase of the loudness of the voice.  相似文献   
57.
Massive sequence comparisons as a help in annotating genomic sequences.   总被引:1,自引:0,他引:1  
An all-by-all comparison of all the publicly available protein sequences from plants has been performed, followed by a clusterization process. Within each of the 1064 resulting clusters-containing sequences that are orthologous as well as paralogous-the sequences have been submitted to a pyramidal classification and their domains delineated by an automated procedure à la. This process provides a means for easily checking for any apparent inconsistency in a cluster, for example, whether one sequence is shorter or longer than the others, one domain is missing, etc. In such cases, the alignment of the DNA sequence of the gene with that of a close homologous protein often reveals (in 10% of the clusters) probable sequencing errors (leading to frameshifts) or probable wrong intron/exon predictions. The composition of the clusters, their pyramidal classifications, and domain decomposition, as well as our comments when appropriate, are available from http://chlora.infobiogen.fr:1234/PHYTOPROT.  相似文献   
58.
Different policies relating to the employment of disabled people coexist in France. They rely on various mechanisms, such as quotas, non-discrimination, professional rehabilitation that corresponds to concurrent, or even antagonist, definitions of disability and participation in the labor market. Based on two original qualitative sociological surveys conducted by semi-structured interviews, this article explores how disability officers grasp, or do not grasp, the different legal tools available to implement employment policies for people with disabilities in public sector work organizations. Despite the strong persistence of an individual, medical, and defective approach to disability in employment, we show that disability officers strive to build a more ambitious, proactive, and systemic policy. They are sensitive to the environmental dimension of disability and to the prevention of disability at work, but do not make reference to the antidiscrimination law and its injunction to pursue equality and inclusion.  相似文献   
59.
60.
BackgroundSubretinal fluid is a risk factor for growth and malignant transformation of choroidal naevi, however it is unclear if this applies to subclinical fluid that is only detectable by optical coherence tomography (OCT). The objective of this study was to determine the prevalence and associations of subclinical but OCT-detectable subretinal fluid over choroidal naevi.MethodsCross-sectional study of 309 consecutive cases of choroidal naevi imaged by OCT between July 2017 to January 2019. Multicentre international study involving ten retinal specialist centres. All patients presenting to retinal specialists had routine clinical examination and OCT imaging. The prevalence of subclinical OCT-detectable subretinal fluid over choroidal naevi and its associations with other features known to predict growth and malignant transformation were noted and analysed.ResultsOf 309 identified consecutive cases, the mean patient age was 65 years, 89.3% of patients were Caucasian and 3.9% were Asian. The prevalence of subclinical but OCT-detectable subretinal fluid associated with choroidal naevi was 11.7% (36/309). Naevi with fluid were associated with larger basal diameters, greater thickness, presence of a halo, orange pigmentation, hyperautofluorescence, and hypodensity on B-scan ultrasonography.Conclusion and relevanceOf choroidal naevi where subretinal fluid is not visible on clinical examination, 11.7% demonstrate subretinal fluid on OCT scans. These naevi more commonly exhibit features known to be associated with growth and transformation to melanoma. The presence of subclinical OCT-detectable fluid over choroidal naevi may assist in their risk stratification.Subject terms: Risk factors, Uveal diseases, Eye manifestations  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