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   48344篇
  免费   3515篇
  国内免费   211篇
耳鼻咽喉   572篇
儿科学   1045篇
妇产科学   977篇
基础医学   6690篇
口腔科学   1032篇
临床医学   4788篇
内科学   10169篇
皮肤病学   1111篇
神经病学   4566篇
特种医学   2090篇
外国民族医学   2篇
外科学   8648篇
综合类   517篇
一般理论   76篇
预防医学   2692篇
眼科学   943篇
药学   2828篇
中国医学   77篇
肿瘤学   3247篇
  2023年   471篇
  2022年   921篇
  2021年   1724篇
  2020年   1029篇
  2019年   1362篇
  2018年   1532篇
  2017年   1040篇
  2016年   1215篇
  2015年   1401篇
  2014年   1894篇
  2013年   2209篇
  2012年   3564篇
  2011年   3510篇
  2010年   1991篇
  2009年   1759篇
  2008年   2741篇
  2007年   2804篇
  2006年   2598篇
  2005年   2417篇
  2004年   2232篇
  2003年   2040篇
  2002年   1867篇
  2001年   530篇
  2000年   525篇
  1999年   545篇
  1998年   474篇
  1997年   377篇
  1996年   289篇
  1995年   270篇
  1994年   241篇
  1993年   240篇
  1992年   372篇
  1991年   344篇
  1990年   314篇
  1989年   289篇
  1988年   274篇
  1987年   257篇
  1986年   243篇
  1985年   269篇
  1984年   221篇
  1983年   214篇
  1982年   181篇
  1981年   167篇
  1980年   182篇
  1979年   183篇
  1978年   154篇
  1977年   149篇
  1976年   142篇
  1974年   142篇
  1972年   121篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Differential Cellular Gene Expression in Ganglioglioma   总被引:1,自引:0,他引:1  
Summary:  Purpose:  Gangliogliomas (GGs) are neuronal-glial tumors highly associated with epilepsy. We hypothesized that the expression of select gene families including neurotransmitter receptor subunits and growth factors would be distinct in neurons and astrocytes within GG compared with adjacent cortex and that these changes would yield insights into seizure onset and lesion formation.
Methods:  Candidate gene expression was defined in single immunohistochemically labeled neurons and astrocytes microdissected from GG specimens compared with neurons and astrocytes microdissected from morphologically intact cortex adjacent to the GG or normal control cortex.
Results:  Differential expression of 16 genes including glutamate transporter (EAAC1) and receptor (NMDA2C, mGluR5), growth factor (hepatocyte growth factor), and receptor (platelet derived growth factor receptor β, fibroblast growth factor receptor 3) mRNAs was detected in GG neurons compared with control neurons. In astrocytes, altered expression of p75NGF, mGluR3, TGFβ3 and Glt-1 mRNAs was detected. Nestin mRNA, a gene that exhibits enhanced expression in balloon cell cortical dysplasia, was increased in GG neurons. Because of the morphological similarities between GG and cortical dysplasia, we show that there is activation of the mTOR cascade in GG as evidenced by enhanced expression of phospho-p70S6kinase and phosphoribosomal S6 proteins.
Conclusion:  We find differential candidate gene expression in neurons and astrocytes in GG compared with adjacent cortex and show that there is activation of the mTOR pathway. These changes highlight pathways that may be pivotal for epileptogenesis and lesion growth.  相似文献   
102.
During development, the genetic content of each cell remains, with a few exceptions, identical to that of the zygote. Differentiated cells, therefore, retain all the genetic information necessary to generate an entire organism (nuclear totipotency). Nuclear transfer (NT) was initially developed to test experimentally this concept by cloning animals from differentiated cells. It has, since then, been used to study the role of genetic and epigenetic alterations during development and disease. In this review, we highlight some of the milestones in mammalian NT reached in the 50 years after the first nuclear transplantations in frogs. We also address problems associated with mammalian nuclear transfer and provide a survey on current NT and stem cell technology. In the long term, nuclear transfer or alternative strategies aim to generate customized pluripotent cells, which would be invaluable to medical research and therapy.  相似文献   
103.
The results of nonoperative treatment of 72 patients with complete anterior cruciate ligament (ACL) tears, documented by examination under anesthesia and arthroscopy, were evaluated. All patients had an acute injury with hemarthrosis in a previously normal knee. Patients having meniscal repair were excluded as were those with collateral or posterior cruciate ligament tears or associated fractures. Treatment in all cases consisted of a standard protocol of early rehabilitation and bracing. A detailed rating of symptoms and function was performed at an average of 38 months postinjury (range, eight to 84 months). Overall results were 11% excellent, 20% good, 15% fair, and 54% poor. Thirty-five percent had ACL reconstruction during the follow-up period. Results indicate that young adults who return to a vocation requiring strenuous physical activity frequently can expect unsatisfactory results after nonoperative treatment of an acute complete tear of the ACL.  相似文献   
104.
Retinopathy is a likely complication of diabetes mellitus, and optometrists who manage patients with diabetes must be prepared to recognize the disease, educate the patient, communicate with the physician treating the disease, and follow up as appropriate to minimize the opportunity for undiagnosed complications. Liability most often results from failure to diagnose diabetic retinopathy, failure to monitor retinopathy adequately, and failure to refer or obtain consultation in a timely manner. Care for patients with diabetes should include appropriate record-keeping and documentation.  相似文献   
105.
Wilson's disease is a hereditary autosomal recessive disorder of copper metabolism. The corresponding gene locus has been localized on the long arm of chromosome 13. Three different clinical variants of the disease can be distinguished: hepato-cerebral, abdominal/hepatic, and central nervous type. The heterogeneity of symptoms can cause problems in differential diagnosis, especially when another concordant disorder can also explain the pathogenesis of symptoms. The case report of a young man who suffered from brainstem contusion demonstrates the possibilities of misinterpretation because presenting symptoms could be attributed either to traumatic brain injury followed by adjustment disorder or Wilson's disease. Clinical signs included leftsided hemiparesis, bilateral gaze direction nystagmus, marked dysarthria with consecutive pervasive mutism, choreo-athetoid movements, spasmodic torticollis and diplopia dependent on gaze direction. Slit lamp examination showed Kayser-Fleischer's corneal ring. EEG- and computer assisted tomography investigations revealed non-specific findings. The patient was treated with D-Penicillamine. Alternative treatment with oral zinc preparations is discussed.
Zusammenfassung Beim Morbus Wilson handelt es sich um eine autosomal rezessiv vererbte Störung des Kupferstoffwechsels. Der Genort konnte auf dem langen Arm des Chromosoms 13 lokalisiert werden. Klinisch können aufgrund ihrer Symptomatik drei Verlaufsformen (hepato-zerebraler, abdominalhepatischer und zerebraler Typ) unterschieden werden. Die Vielfalt der Symptome kann differentialdiagnostische Schwierigkeiten bereiten. Das Beispiel eines jungen Mannes mit einer traumatischen Hirnstammkontusion zeigt, wie die Diagnose der hepato-lentikulären Erkrankung dadurch erschwert wurde, daß die Pathogenese der Symptome durch die Hirnstammkontusion und darauf folgende Anpassungsstörungen erklärt worden war. Die Symptomatik bestand aus linksseitiger Hemiparese, lateralem Blickrichtungsnystagmus, Dysarthrie mit nachfolgendem universalem Mutismus, choreo-athetodischen Bewegungsstörungen, Torticollis spasmoidicus und blickrichtungsabhängigem Auftreten von Doppelbildern. Bei der Spaltlampenuntersuchung stellte sich der Kayser-Fleischer Ring dar. EEG- und computertomographische Untersuchungen erbrachten nur unspezifische Befunde. Die Behandlung erfolgte mit D-Penicillamin. Die alternative Behandlung mit oraler Gabe von Zinksalzen wird diskutiert.

Résumé La maladie de Wilson est une affection héréditaire autosomale recessive concernant le métabolisme cuivré. Le locus du gène a été situé sur le bras long du chromosome 13. Du point de vue clinique on distingue trois formes symptomatologiques: le type hepato-cérébral, hepato-abdominal et cérébral. La diversité des signes cliniques peut poser des problèmes de diagnostic différentiel, car d'autres affections peuvent se présenter avec cette même Symptomatologie. Nous rapportons ici l'exemple d'un homme jeune, porteur d'une maladie de Wilson et victime d'une contusion traumatique du tronc cérébral, dont les signes cliniques ainsi que les troubles du comportement pouvaient été autant rapportés à la contusion du tronc cérébral qu'à l'affection métabolique.La Symptomatologie comprenait une hemiparesie gauche, un nystagmus lateralisé, une dysarthrie avec mutisme secondaire universel, des mouvements choréo-athétosiques, un torticolis spasmodique et une diplopie dépendante de la direction du regard. L'examen à la lampe à fente permettait à mettre en evidence un anneau de Kayser Fleischer. L'EEG et le scanner cérébral ne montraient pas d'anomalies specifique.Le traitement a consisté en l'administration de D-Penicillamine. Traitment alternative avec les sels de zinc est discuté.
  相似文献   
106.
107.
108.
We report the first case of a unilateral microcysticMeesmann‘s epithelial dystrophy, observed in the left cornea of a 43-year-old patient. The diagnosis was verified histologically by the unilateral occurrence of a ’peculiar substance‘ within epithelial cysts and within the cytoplasm of the corneal epithelial cells. In an attempt to resolve thepatient‘s frequent corneal erosions, we performed an autologous stem cell transplantation from the non-involved right eye. The results are, so far, satisfactory. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
109.
We investigated non-rapid eye movement (non-REM) sleep in patients with newly diagnosed Parkinson's disease (PD) who had never previously received dopaminergic medication. There were no significant differences in the conventional sleep parameters between de novo patients with PD and a healthy control group, but the length of stage 1 sleep and the number of awakenings increased significantly upon administration of dopaminergic drugs. Analyzing the quantitative electroencephalogram (EEG), we observed a significant reduction in the low-delta frequency range and a nonsignificant increase in the sigma frequency range in de novo patients with PD. The dopaminergic medication also nonsignificantly reduced the low-delta and sigma frequencies, the latter to the level of the controls. Possible mechanisms that may account for the observed differences are discussed. It is suggested that Parkinson's disease as well as the application of dopaminergic drugs exerts a desynchronizing effect on the sleep EEG that is reflected in a disruption of sleep continuity.  相似文献   
110.
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