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   8560篇
  免费   525篇
  国内免费   25篇
耳鼻咽喉   128篇
儿科学   269篇
妇产科学   263篇
基础医学   866篇
口腔科学   140篇
临床医学   785篇
内科学   2211篇
皮肤病学   80篇
神经病学   865篇
特种医学   360篇
外科学   949篇
综合类   93篇
一般理论   6篇
预防医学   972篇
眼科学   156篇
药学   556篇
中国医学   2篇
肿瘤学   409篇
  2023年   32篇
  2022年   19篇
  2021年   171篇
  2020年   83篇
  2019年   167篇
  2018年   192篇
  2017年   161篇
  2016年   145篇
  2015年   170篇
  2014年   280篇
  2013年   391篇
  2012年   631篇
  2011年   688篇
  2010年   377篇
  2009年   374篇
  2008年   568篇
  2007年   689篇
  2006年   640篇
  2005年   615篇
  2004年   577篇
  2003年   527篇
  2002年   471篇
  2001年   120篇
  2000年   80篇
  1999年   93篇
  1998年   106篇
  1997年   76篇
  1996年   47篇
  1995年   72篇
  1994年   47篇
  1993年   45篇
  1992年   49篇
  1991年   31篇
  1990年   36篇
  1989年   62篇
  1988年   37篇
  1987年   24篇
  1986年   21篇
  1985年   17篇
  1984年   30篇
  1983年   17篇
  1982年   21篇
  1981年   18篇
  1980年   16篇
  1979年   7篇
  1978年   14篇
  1977年   10篇
  1976年   9篇
  1974年   6篇
  1971年   6篇
排序方式: 共有9110条查询结果,搜索用时 292 毫秒
91.
A national household probability sample of 4,023 adolescents aged 12 to 17 years was surveyed by telephone via structured clinical interview to determine the impact of familial substance use, sexual and physical assault, witnessed violence, depression and posttraumatic stress disorder (PTSD) on risk of smoking. Results indicated that familial substance use increased risk of smoking only for boys and sexual assault or depression increased risk of smoking only for girls. Age, Caucasian ethnicity, and experiencing physical assault or witnessing violence elevated risk of current cigarette use for both genders. By contrast, PTSD per se was not associated with increased risk of smoking, after the effects of other variables were controlled.  相似文献   
92.
To update its cancer statistics, the newly established Middle East Cancer Society examined the cancer frequency patterns in Egypt and the Gaza Strip. The results revealed differing overall patterns. For men the highest frequencies were found for lymphoma, bladder cancer and cancers of the oral cavity and pharynx in Egypt, and for lung cancer, leukaemia and lymphoma in Gaza. For women, breast cancer had the highest frequency in both areas, followed by cancers of the oral cavity and pharynx in Egypt, and leukaemia and lymphoma in Gaza. The distribution of cancer occurrence by organ system also varied. In the light of the different ethnicities, lifestyles, socioeconomic levels and carcinogenic exposure among the countries of the Middle East, this kind of comparison can provide the background for more sophisticated approaches for discerning risk factors in cancer. We believe that further cooperation among participating countries will overcome the present limitations in data collection, registration and access.  相似文献   
93.
94.
A novel serum 21 kDa haptoglobin-related protein (Hpr) was investigated in patients with malignant lymphoma, to evaluate its correlation with clinical and histologic features at presentation and its possible role as a tumor marker for patient outcome. One hundred fifty eight serum samples were taken from 88 patients with non-Hodgkin’s lymphoma (n=58) and Hodgkin’s disease (n=30) at presentation and in the course of follow-up. Sera from 61 healthy volunteers served as normal controls. Serum Hpr levels in the lymphoma patients (median 430xl03 u/ml, range 0-4000xl03) were significantly higher than in the control group (median 68xl03 u/ml, range 0-180xl03) (p=0.0001). Higher median Hpr values were detected in patients with advanced disease (p=0.013), “B” symptoms (p=0.029) and in males (p=0.053). There was also a significant correlation between Hpr and erythrocyte sedimentation rate (p=0.028). Serial determinations showed a significant decrease of the initial Hpr values obtained after treatment in 41 patients, 38 of whom achieved complete remission. In the follow-up period additional Hpr measurements were taken from 17 patients. Three of them eventually relapsed, and showed increased Hpr levels at the time of relapse. Hpr levels remained low in 11 of 14 patients who maintained complete remission, and increased in three. In conclusion, serum Hpr is a new serum tumor marker of potential use in the clinical setting of lymphoma. This work is dedicated to the memory of Dr. Arie H. Bartal, a dedicated oncologist and friend. This work was supported by Chemotech Thechnologies Ltd., by grant no. 3676 from the Chief Scientist’s Office of the Ministry of Health, Israel, and by the Fund for Promotion of Research in the Technion.  相似文献   
95.
OBJECTIVES: Diffusion tensor imaging (DTI), a technique capable of examining water diffusion in different tissues and the organisation of white matter tracts, was used to investigate the neuropathology of the corpus callosum in vivo in patients with schizophrenia. METHODS: Diffusion tensor imaging was performed in 20 schizophrenic patients and 25 healthy controls. Two complementary measures, mean diffusivity and fractional anisotropy, which are considered to be sensitive indices of axonal integrity, were obtained from regions of interest in the genu (anterior) and splenium (posterior) of the corpus callosum. RESULTS: Mean diffusivity was significantly increased and fractional anisotropy significantly reduced in the splenium but not the genu of the corpus callosum in the schizophrenic group compared with controls. There were no significant sex differences in the DTI measures for either the schizophrenic or control group. Clinical variables such as age, duration of illness, dose of antipsychotic medication, and schizophrenic symptoms did not predict the DTI changes in the schizophrenic patients. CONCLUSIONS: The presence of DTI changes in the splenium but not the genu of the corpus callosum suggests that there may be a focal disruption of commisural connectivity in schizophrenia. However, these findings do not exclude the possibility of abnormalities in other areas of the corpus callosum or other regions of white matter and further research using different methods of analysis may enable us to clarify this. Diffusion tensor imaging is a valuable tool in investigating the structure of white matter in schizophrenia.  相似文献   
96.
Susac syndrome.     
OBJECTIVE: The objective of this study was to describe the clinical manifestations; radiographic, audiometric, and retinal fluorescein angiography findings; pathogenesis and treatment of Susac syndrome with review of the literature. STUDY DESIGN: We conducted a retrospective case review. SETTING: This study was conducted at a tertiary referral center. PATIENT: A 50-year-old woman presented with recurrent episodes of neurologic symptoms, bilateral sensorineural hearing loss, and silent retinal artery occlusion. INTERVENTIONS: The patient underwent complete evaluation, including magnetic resonance image studies, audiometric tests, and retinal fluorescein angiography. She was treated initially with corticosteroids and later with other immunosuppressive agents. RESULTS: The patient was initially diagnosed with left sudden sensorineural hearing loss. Despite comprehensive clinical and laboratory studies that did not reveal systemic disease, 3 weeks later, the patient developed vertigo, sensorineural hearing loss, and tinnitus in the opposite ear. The neurologic involvement and the bilateral audiologic manifestations raised the possibility of Susac syndrome. CONCLUSION: Susac syndrome is a rare disorder of unknown origin characterized by the triad of encephalopathy, fluctuating hearing loss, and visual loss resulting from microangiopathy of the brain, cochlea, and retina. The multiple organ involvement seen in Susac syndrome raises a differential diagnosis ranging from autoimmune disease, through systemic vasculitis, to multiple sclerosis. Otolaryngologists should be aware of this syndrome as a result of the vestibulocochlear manifestations and the multidisciplinary evaluation that is required.  相似文献   
97.
98.
We describe a novel form of myopathy in a mother and her two daughters from an inbred Samaritan family. The patients displayed severe neonatal hypotonia, lethargy and dysmorphic features. Motor milestones were delayed; however, the hypotonia and muscle weakness gradually improved during the first 2 years of life and independent walking was achieved by 18 months. The mother at the age of 23 years shows myopathic facies and minimal proximal weakness. Her intelligence is normal. Her muscle biopsy revealed central nuclei and disruption of the intermyofibrillary network with moth eaten and spiral fibers. Mutations in SMN, MTM1 and the myotonic dystrophy genes were excluded. We suggest this is a new benign form of congenital myopathy. Inheritance is probably autosomal recessive.  相似文献   
99.
A recent study has suggested that a dodecamer duplication in the HOPA gene in Xq13 may occur in a significant portion of male patients with autism. We have determined the incidence of this duplication in 202 patients from the South Carolina Autism Study. The incidence of the duplication was not significantly different between patients and controls. Three of the female patients inherited the duplication from nonautistic fathers. In addition, there was no systematic skewing of X inactivation in the female patients with the duplication, or in nonautistic mothers and sisters with the duplication. These findings suggest that the dodecamer duplication in the HOPA gene does not play a significant role in the etiology of autism.  相似文献   
100.
PURPOSE: In biopsies of patients with locally advanced breast cancer, we investigated the in vivo changes of the gene expression pattern induced by chemotherapy to find genes that are potentially responsible for the efficacy of the drug. EXPERIMENTAL DESIGN: Early cellular responses to chemotherapy-induced damage, both in vivo and in vitro, were investigated by analyzing chemotherapy-induced changes in gene expression profiles. Core biopsies were taken from nine patients with locally advanced breast cancer, before and at 6 hours after initiation of doxorubicin-based chemotherapy. Both samples were cohybridized on the same microarray containing 18,000 cDNA spots. RESULTS: The analysis revealed marked differences in gene expression profile between treated and untreated samples. The gene which was most frequently found to be differentially expressed was p53 up-regulated modulator of apoptosis (PUMA). This gene was up-regulated in eight of nine patients with an average factor of 1.80 (range, 1.36-2.73). In vitro MCF-7 breast cancer cells exposed to clinically achievable doxorubicin concentrations for 6 hours revealed marked induction of PUMA mRNA, as well. CONCLUSIONS: This is the first report describing PUMA mRNA to be up-regulated as a response to chemotherapy in patients. Because PUMA is a known member of the family of BH3-only proapoptotic proteins, this finding suggests PUMA's potential importance for the response to anticancer drugs.  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