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   31121篇
  免费   2259篇
  国内免费   527篇
耳鼻咽喉   486篇
儿科学   1166篇
妇产科学   489篇
基础医学   2459篇
口腔科学   1211篇
临床医学   3267篇
内科学   4925篇
皮肤病学   453篇
神经病学   8595篇
特种医学   539篇
外科学   1451篇
综合类   2350篇
现状与发展   3篇
一般理论   1篇
预防医学   3325篇
眼科学   215篇
药学   2113篇
  8篇
中国医学   533篇
肿瘤学   318篇
  2024年   127篇
  2023年   748篇
  2022年   1001篇
  2021年   1556篇
  2020年   1492篇
  2019年   1387篇
  2018年   1367篇
  2017年   1324篇
  2016年   1253篇
  2015年   1145篇
  2014年   1889篇
  2013年   2824篇
  2012年   1533篇
  2011年   1790篇
  2010年   1372篇
  2009年   1451篇
  2008年   1513篇
  2007年   1368篇
  2006年   1202篇
  2005年   957篇
  2004年   827篇
  2003年   854篇
  2002年   662篇
  2001年   476篇
  2000年   425篇
  1999年   390篇
  1998年   368篇
  1997年   322篇
  1996年   250篇
  1995年   243篇
  1994年   210篇
  1993年   186篇
  1992年   194篇
  1991年   142篇
  1990年   144篇
  1989年   81篇
  1988年   101篇
  1987年   96篇
  1986年   74篇
  1985年   112篇
  1984年   85篇
  1983年   60篇
  1982年   56篇
  1981年   47篇
  1980年   45篇
  1979年   43篇
  1978年   34篇
  1977年   31篇
  1976年   15篇
  1975年   10篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
BACKGROUND: There is an increasing recognition that the pathophysiology of mental disorders could be the result of deregulation of synaptic plasticity with alterations of neurotrophins. The valine (Val)66-to-methionine (Met) variant, located in the pro brain-derived neurotrophic factor (BDNF) sequence, has been extensively studied through linkage and association approaches in several psychiatric disorders. METHODS: We performed a meta-analysis restricted to individual case-control studies in different categories of mental disorders and BDNF Val66Met polymorphism. We included data from 39 case-control studies encompassing psychiatric phenotypes: eating disorders, substance-related disorders, mood disorders, and schizophrenia, among others. RESULTS: The association of Val66Met was confined to three diagnoses: substance-related disorders, eating disorders, and schizophrenia. The Val/Met and the Met/Met genotypes increase the risk for eating disorders up to 33%, while these same genotypes confer a 21% protective effect in substance-related disorders. The homozygous carriers Met/Met showed a 19% increased risk of schizophrenia with respect to the heterozygous state. CONCLUSIONS: The study confirms the association of Val66Met to substance-related disorders, eating disorders, and schizophrenia. It remains to be determined if other variants in tight linkage disequilibrium with Val66Met could configure an extended functional haplotype that would explain observed discrepancies in risk estimations across studies.  相似文献   
92.
抗心磷脂抗体与脑血管病关系的研究   总被引:2,自引:0,他引:2  
目的:探讨抗心磷脂抗体(aCL)与脑血管病(CVD)的关系。方法:检测266例缺血性脑血管病(ICVD)患者和73例脑出血(CH)患者血清aCL。结果:ICVD患者aCL阳性率高于对照组(P<0.01),且IgG型aCL比IgM型aCL阳性率升高(P<0.01)。CH患者aCL阳性率高于对照组(P<0.01)。ICVD组aCL阳性率与CH组比较无显著性差异(P>0.05),ICVD组、CH组和对照组不同性别间aCL阳性率无显著性差异(P>0.05)。结论:aCL可作为CVD危险性增加的指标,对CVD的预测有一定意义,包括ICVD和CH患者,aCL阳性率男女性别之间无差异。  相似文献   
93.
94.
Bilateral perioral sensory dysfunction due to unilateral cerebral lesion is rare, and has been thought to be caused by midline brainstem lesions. Six patients are described herewith, with bilateral perioral sensory symptoms due to unilateral strokes that do not involve the mid-brainstem region. Brain-computed tomographic scan and magnetic resonance imaging demonstrated unilateral cerebral strokes in the thalamus, posterior limb of the internal capsule, basal ganglia, fronto-parietal cortex and the insular-frontal subcortical area. This observation suggests that bilateral perioral sensory symptoms do not have a localizing value. Possible pathogenetic mechanisms for this sign are discussed.  相似文献   
95.
A patient with neutropenia and life-threatening infections secondary to T-γ lymphoproliferative disease, who did not respond to treatment with recombinant human G-CSF (filgrastim), was treated with filgrastim plus cyclosporine A (CyA). The patient achieved a good response in the absolute neutrophil count and subsequently required a dose reduction in the filgrastim. The patient was eventually discontinued from the CyA but continues on filgrastim alone. While on therapy, the large granular lymphocytes disappeared from the circulation and the beta-TCR rearrangement, which was present prior to beginning therapy, became undetectable. The patient had no significant toxicity to the CyA or the filgrastim and he has not experienced any serious infections or required hospitalization. Filgrastim has proven to be relatively nontoxic and of some benefit to patients with this disease and should probably be utilized first when treatment is necessary. However, if improvement is not observed, these findings suggest that a trial of the combination of CyA plus filgrastim may be beneficial.  相似文献   
96.
A wireless device for the assessment of tardive dyskinesia by means of digital image processing is presented. Four skin-cream dots placed around the subjects' mouth are recorded by a video camera. The image is passed to a framegrabber with a signal processor, where it is converted from analogue to digital. A fast spot-detecting algorithm implemented on the signal processor tracks the dots and passes the information to a personal computer, where a Fourier transformation is performed to calculate the frequency spectrum of the movements. The device provided detailed information on the magnitude and on the frequencies of the movements. Data from a longitudinal investigation suggest a higher sensitivity and reliability than conventional rating scales to detect and evaluate abnormal perioral movements. The device might be useful for the early detection, for the longitudinal assessment (p.e. clinical trials) and in some cases for the differential diagnosis of tardive dyskinesia, thus providing a tool for both research and clinical purposes.  相似文献   
97.
Magnetic Resonance Imaging in Patients with Bone Marrow Disorders   总被引:7,自引:0,他引:7  
Magnetic resonance imaging (MRI) provides a non-invasive means to evaluate a large fraction of marrow in less than one hour. Marrow disorders produce non-specific changes in marrow signal intensities which primarily reflect changes in proportions of fat and cellular elements. The pattern of these signal changes narrows the differential diagnosis, and the combination of these features with the clinical context allows interpretations which are clinically useful in many ways. These include: I) the diagnosis of avascular necrosis (and its distinction from other causes of joint pain), 2) detection of osteomyelitis, 3) differential diagnosis of hypo-plastic disorders, 4) staging of lymphomas and myeloma, 5) selection of patients for autolo-gous bone marrow transplant, 6) objective measures of marrow response to therapy, 7) detection of leukemic transformation, and 8) improved detection of marrow disease (primary or secondary) in patients with otherwise unexplained bone pain.  相似文献   
98.
The validity of a simple clinical classification of acute ischaemic stroke   总被引:6,自引:0,他引:6  
The aim of the study reported here was to test the validity of a simple clinical classification of acute ischaemic stroke (Oxfordshire Community Stroke Project, OCSP) in predicting the site and size of cerebral infarction on computed tomography (CT). Consecutive patients admitted to hospital with acute ischaemic stroke were prospectively identified and classified into one of four clinical syndromes according to the OCSP classification, blind to the result of CT. The CT brain scans were classified blind to the clinical features into those demonstrating: small, medium or large cortical infarcts; small or large subcortical infarcts in the anterior circulation territory; and posterior cerebral circulation territory infarcts. A total of 108 patients were included. A recent infarct was seen. on the CT scan in 91 patients (84%), and the clinical classification correctly predicted the site and size of the cerebral infarct in 80 of these (88%; 95% confidence interval 77–92%). The positive predictive value was best for large cortical infarcts (0.94) and worst for small subcortical infarcts (0.63). The OCSP clinical classification is a reasonably valid way of predicting the site and size of cerebral infarction on CT and can, therefore, be used very early after stroke onset before the infarct appears on the scan.  相似文献   
99.
So far, laparoscopic approaches to kidney and adrenal have been limited because of their retroperitoneal location. We here report eight renal and adrenal endoscopic procedures performed in seven patients: two adrenalectomies for hyperaldosteronism, one adrenalectomy for isolated metastasis from an adenocarcinoma of the lung; two nephrectomies for end-stage infected hydronephrosis, two partial nephrectomies for small circumscribed lesions of the kidney, and one endoscopic resection for pain relief of a voluminous cyst at the kidney. The approach was transperitoneal in two cases and retroperitoneal in five cases using the retropneumoperitoneum insufflation technique. One patient was operated by a combined approach using the retro- and transperitoneal routes. All procedures were successfully completed endoscopically. The retroperitoneoscopic approach of the kidney is safe and does not interfere with the peritoneal organs. Its working space is tenuous, but allows a direct access on the kidney with good exposure of its pedicle. For adrenal surgery, the retroperitoneoscopic dissection is more difficult, because movements of instruments are often impaired by the closeness of the costal margin and the iliac crest. However, in case of difficulties we found it very convenient to switch from a retroperitoneal endoscopic approach to a combined coelioscopic and retroperitoneoscopic operation. Far from excluding each other, both approaches are complementary, particularly for difficult situations (i.e., previous peritoneal or retroperitoneal surgery).  相似文献   
100.
In early infancy, complex disorders of acid base metabolism are more frequent than in any other age group, with a predisposition to metabolic acidosis due to an age-related low renal capacity for acid excretion and an unphysiologically high actual renal acid load in nutrition with common formulas. Recently in preterm and small-for-gestational-age infants, persistent maximum renal net acid excretion (NAE) with subnormal or normal blood acid base status, impaired weight gain, and adaptive hormonal reactions have been observed. Incipient late metabolic acidosis is one example of a mixed disorder of acid base metabolism with maximum renal NAE in early infancy. Alkali therapy is highly effective and can be realized both on an individual basis, using urine pH screening as a diagnostic criterium for maximum renal acid stimulation, or on a general preventive level using modified standard formula with a reduced actual renal NAE similar to that seen on alimentation with human milk. From an integrated point of view, the low glomerular filtration rate and renal capacity for acid excretion beyond the developmental age of more than 44 weeks, may well be interpreted as the result of a specific adaptation to breast feeding sparing energy, and thus an evolutionary advantage for the survival of mother and child. Received July 10, 1996; received in revised form and accepted October 7, 1996  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