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   3699篇
  免费   269篇
  国内免费   16篇
耳鼻咽喉   12篇
儿科学   148篇
妇产科学   78篇
基础医学   642篇
口腔科学   14篇
临床医学   443篇
内科学   774篇
皮肤病学   52篇
神经病学   276篇
特种医学   95篇
外科学   429篇
综合类   11篇
一般理论   1篇
预防医学   431篇
眼科学   56篇
药学   201篇
中国医学   9篇
肿瘤学   312篇
  2024年   4篇
  2023年   20篇
  2022年   75篇
  2021年   127篇
  2020年   73篇
  2019年   120篇
  2018年   84篇
  2017年   57篇
  2016年   84篇
  2015年   92篇
  2014年   147篇
  2013年   203篇
  2012年   275篇
  2011年   299篇
  2010年   170篇
  2009年   176篇
  2008年   243篇
  2007年   265篇
  2006年   231篇
  2005年   237篇
  2004年   226篇
  2003年   207篇
  2002年   244篇
  2001年   33篇
  2000年   20篇
  1999年   29篇
  1998年   50篇
  1997年   33篇
  1996年   26篇
  1995年   24篇
  1994年   18篇
  1993年   18篇
  1992年   8篇
  1991年   3篇
  1990年   6篇
  1989年   5篇
  1988年   6篇
  1987年   2篇
  1986年   6篇
  1985年   2篇
  1984年   9篇
  1982年   5篇
  1981年   4篇
  1980年   2篇
  1976年   2篇
  1970年   2篇
  1967年   2篇
  1965年   1篇
  1964年   2篇
  1949年   1篇
排序方式: 共有3984条查询结果,搜索用时 15 毫秒
81.
There is limited understanding of the mitochondrial adaptation following repeated eccentric exercise bouts, a model resulting in muscle adaptation known as the repeat bout effect. It was hypothesized that downhill training would reduce mitochondrial calcium content (MCC) post an acute eccentric bout with concurrent improvements in mitochondrial respiratory function. Thirty-four Sprague–Dawley rats were divided into four groups: control (N), control with acute eccentric exercise (N ecc), trained control (X) and trained with acute eccentric exercise (X ecc). Training for X and X ecc consisted of 30 min per day for five consecutive days of downhill treadmill running. The acute eccentric exercise bout was a ?14° treadmill exercise for 90 min performed 2 weeks after the training period. Animals were killed 48 h post-exercise. Isolated mitochondria from the red quadriceps allowed for the measure of mitochondrial respiratory indices and MCC. Calpain activity and heat shock protein 72 expression (HSP72) were also measured. MCC dramatically increased following the acute bout of eccentric exercise in N ecc (p < 0.001), but did not change in X ecc. Mitochondrial respiratory function tended to be slightly depressed in N ecc (state 3 respiration, p = 0.053; respiratory control ratio, p = 0.098) and unaltered in X ecc. Previous training altered the calpain and heat shock protein response to an acute bout of eccentric exercise. The results suggest that downhill exercise training improves mitochondrial calcium homeostasis following an acute bout of prolonged eccentric exercise and may stabilize mitochondrial respiratory function. These improvements coincide with a reduction in calpain activity and heat shock protein upregulation.  相似文献   
82.
83.
Aims:The aim was to evaluate the clinical and anatomic outcome of arthroscopic repair of type II SLAP lesions.Results:At a mean follow-up of 54-month, the mean American Shoulder and Elbow Surgeons Shoulder Index (ASES) scores improved from 52.1 preoperatively to 86.1 postoperatively (P < 0.0001) and the Simple Shoulder Test (SST) scores from 7.7 to 10.6 (P < 0.0002). Twenty-two out of the 25 patients (88%) stated that they would have surgery again. Of the 21 patients who had postoperative magnetic resonance imaging arthrographys (MRAs), 9 patients (43%) demonstrated dye tracking between the labrum bone interface suggestive of a recurrent tear and 12 patients (57%) had a completely intact repair. There was no significant difference in ASES, SST, and patient satisfaction scores in patients with recurrent or intact repairs.Conclusions:Arthroscopic repair of type II SLAP lesions demonstrated improvements in clinical outcomes. However, MRA imaging demonstrated 43% of patients with recurrent tears. MRA results do not necessarily correlate with clinical outcome.  相似文献   
84.
The greatest challenge to successful treatment of spinal cord injury is the limited regenerative capacity of the central nervous system and its inability to replace lost neurons and severed axons following injury. Neural stem cell grafts derived from fetal central nervous system tissue or embryonic stem cells have shown therapeutic promise by differentiation into neurons and glia that have the potential to form functional neuronal relays across injured spinal cord segments. However, implementation of fetal-derived or embryonic stem cell-derived neural stem cell therapies for patients with spinal cord injury raises ethical concerns. Induced pluripotent stem cells can be generated from adult somatic cells and differentiated into neural stem cells suitable for therapeutic use, thereby providing an ethical source of implantable cells that can be made in an autologous fashion to avoid problems of immune rejection. This review discusses the therapeutic potential of human induced pluripotent stem cell-derived neural stem cell transplantation for treatment of spinal cord injury, as well as addressing potential mechanisms, future perspectives and challenges.  相似文献   
85.
86.
Polycystic kidney disease (PKD) is one of the most common life-threatening genetic diseases. Jared J. Grantham, M.D., has done more than any other individual to promote PKD research around the world. However, despite decades of investigation there is still no approved therapy for PKD in the United States. In May 2014, the University of Kansas Medical Center hosted a symposium in Kansas City honoring the occasion of Dr. Grantham''s retirement and invited all the awardees of the Lillian Jean Kaplan International Prize for Advancement in the Understanding of Polycystic Kidney Disease to participate in a forward-thinking and interactive forum focused on future directions and innovations in PKD research. This article summarizes the contributions of the 12 Kaplan awardees and their vision for the future of PKD research.  相似文献   
87.
Incidence and prevalence of dementia in the Cardiovascular Health Study   总被引:6,自引:0,他引:6  
OBJECTIVES: To estimate the incidence and prevalence of dementia, Alzheimer's disease (AD), and vascular dementia (VaD) in the Cardiovascular Health Study (CHS) cohort. DESIGN: Longitudinal cohort study using prospectively and retrospectively collected data to evaluate dementia. SETTING: Four U.S. communities. PARTICIPANTS: There were 3,602 CHS participants, including 2,865 white and 492 African-American participants free of dementia, who completed a cranial magnetic resonance image between 1992 and 1994 and were followed for an average of 5.4 years. MEASUREMENTS: Dementia was classified by neurologist/psychiatrist committee review using neuropsychological tests, neurological examinations, medical records, physician questionnaires, and proxy/informant interviews. Demographics and apolipoprotein E (APOE) genotype were collected at baseline. Incidence by type of dementia was determined using National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD and Alzheimer's Disease Diagnostic and Treatment Center's State of California criteria for VaD. RESULTS: Classification resulted in 227 persons with prevalent dementia at entry into the study and 480 incident cases during follow-up. Incidence rates of dementia scaled to age 80 were 34.7 per 1,000 person-years for white women, 35.3 for white men, 58.8 for African-American women, and 53.0 for African-American men. Sex differences were not significant within race. Adjusted for age and education, racial differences were only of borderline significance and may have been influenced by ascertainment methodology. Rates differed substantially by educational attainment but were only significant for whites. Those with the APOE epsilon4 allele had an incidence rate at age 80 of 56.4, compared with 29.6 for those without this allele (P<.001). In whites, type-specific incidence at age 80 was 19.2 for AD versus 14.6 for VaD. These rates were 34.7 and 27.2 for African Americans. At termination of observation, women had only a slightly higher prevalence of dementia (16.0%) than men (14.7%). CONCLUSION: Sex and racial differences were not found, and VaD was higher than reported in other studies. These data provide new estimates of dementia incidence in a community sample for projection of future burden.  相似文献   
88.

Listeriosis

is a foodborne illness that can result in septicaemia, Central Nervous System (CNS) disease, foetal loss and death in high risk patients.

Objectives

To analyse the demographic trends, clinical features and treatment of non-perinatal listeriosis cases over a ten year period and identify mortality-associated risk factors.

Methods

Reported laboratory-confirmed non-pregnancy associated cases of listeriosis between 2006 and 2015 in England were included and retrospectively analysed. Multivariate logistic regression analysis was performed to determine independent risk factors for mortality.

Results

1357/1683 reported cases met the inclusion criteria. Overall all-cause mortality was 28.7%; however, mortality rates declined from 42.1% to 20.2%. Septicaemia was the most common presentation 69.5%, followed by CNS involvement 22.4%. CNS presentations were significantly associated with age?<?50 years, and septicaemia with older age. Age?>?80 years (OR 3.32 95% CI 1.92–5.74), solid-organ malignancy (OR 3.42 95% CI 2.29-5.11), cardiovascular disease (OR 3.30 95% CI 1.64–6.63), liver disease (OR 4.61 95% CI 2.47–8.61), immunosuppression (OR 2.12 95% CI 1.40-3.21) and septicaemia (OR 1.60 95% CI 1.17–2.20) were identified as independent mortality risk factors.

Conclusions

High risk groups identified in this study should be the priority focus of future public health strategies aimed at reducing listeriosis incidence and mortality.  相似文献   
89.
OBJECTIVE: To analyze hematopoietic and immune reconstitution after autologous hematopoietic stem cell transplantation (HSCT) in 7 patients with systemic sclerosis (SSc). METHODS: Two groups of patients were retrospectively constituted according to whether they had a favorable clinical response (group A; n = 4) or no response or a relapse of disease (group B; n = 3) after HSCT. Immune reconstitution was analyzed every 3 months using lymphocyte immunophenotyping, alpha/beta T cell receptor (TCR) diversity analysis, and ex vivo thymic function analysis by quantification of TCR rearrangement excision circles (TRECs). RESULTS: Patients had similar characteristics at study entry, except for a lower modified Rodnan skin thickness score (P = 0.03) and a lower Health Assessment Questionnaire score (P = 0.05) in group A than in group B. The number of reinjected cells and the time to hematopoietic reconstitution were similar in both groups. The absolute numbers of CD19+ and CD20+ B cells were lower in group A than in normal controls (P < 0.05) and within the normal range in group B. Absolute numbers of T and natural killer lymphocytes were normal before HSCT. Numbers of CD3+ cells remained low thereafter. Numbers of CD8+ cells were back to normal 3 months after HSCT in both groups. B cell counts were low until 6 months after HSCT in group A and stayed in the normal range in group B. The CD3+ defect was sustained in group A, with an opposite trend and a faster CD4+ reconstitution profile in group B. The T cell repertoire was skewed before and until 1 year after HSCT, with shared expansions before and after transplant in a given individual. TREC values correlated negatively with C-reactive protein levels (r(s) = -0.41, P = 0.001) and positively with CD19+ (r(s) = 0.35, P = 0.001) and CD20+ (r(s) = 0.34, P = 0.002) lymphocyte counts. CONCLUSION: B and T lymphocyte populations remained disturbed for at least 1 year after HSCT in SSc patients, which may reflect the persistence of an underlying disease mechanism.  相似文献   
90.
The FL2000 study was undertaken to evaluate the combination of the anti-CD20 monoclonal antibody rituximab with chemotherapy plus interferon in the first-line treatment of follicular lymphoma patients with a high tumor burden. Patients were randomly assigned to receive either 12 courses of the chemotherapy regimen CHVP (cyclophosphamide, adriamycin, etoposide, and prednisolone) plus interferon-alpha2a (CHVP+I arm) over 18 months or 6 courses of the same chemotherapy regimen combined with 6 infusions of 375 mg/m(2) rituximab and interferon for the same time period (R-CHVP+I arm). After a median follow-up of 5 years, event-free survival estimates were, respectively, 37% (95% confidence interval [CI], 29%-44%) and 53% (95% CI, 45%-60%) in the CHVP+I and R-CHVP+I arm (P = .001). Five-year overall survival estimates were not statistically different in the CHVP+I (79%; 95% CI, 72%-84%) and R-CHVP+I (84%; 95% CI, 78%-84%) arms. In a multivariate regression analysis, event-free survival was significantly influenced by both the Follicular Lymphoma International Prognostic Index score (hazard ratio = 2.08; 95% CI, 1.6%-2.8%) and the treatment arm (hazard ratio = 0.59; 95% CI, 0.44%-0.78%). With a 5-year follow-up, the combination of rituximab with CHVP+I provides superior disease control in follicular lymphoma patients despite a shorter duration of chemotherapy. This study's clinical trial was registered at the National Institutes of Health website as no. NCT00136552.  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