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   8735篇
  免费   539篇
  国内免费   44篇
耳鼻咽喉   79篇
儿科学   231篇
妇产科学   92篇
基础医学   1211篇
口腔科学   213篇
临床医学   611篇
内科学   2262篇
皮肤病学   258篇
神经病学   740篇
特种医学   327篇
外科学   1043篇
综合类   41篇
一般理论   2篇
预防医学   444篇
眼科学   182篇
药学   612篇
中国医学   18篇
肿瘤学   952篇
  2023年   90篇
  2022年   143篇
  2021年   269篇
  2020年   162篇
  2019年   212篇
  2018年   261篇
  2017年   199篇
  2016年   262篇
  2015年   258篇
  2014年   356篇
  2013年   416篇
  2012年   610篇
  2011年   659篇
  2010年   348篇
  2009年   319篇
  2008年   578篇
  2007年   603篇
  2006年   488篇
  2005年   488篇
  2004年   493篇
  2003年   436篇
  2002年   446篇
  2001年   129篇
  2000年   106篇
  1999年   102篇
  1998年   94篇
  1997年   73篇
  1996年   80篇
  1995年   42篇
  1994年   41篇
  1993年   36篇
  1992年   70篇
  1991年   53篇
  1990年   66篇
  1989年   41篇
  1988年   32篇
  1987年   34篇
  1986年   30篇
  1985年   28篇
  1984年   25篇
  1983年   21篇
  1982年   13篇
  1981年   8篇
  1980年   9篇
  1979年   14篇
  1978年   8篇
  1974年   7篇
  1970年   6篇
  1969年   6篇
  1967年   6篇
排序方式: 共有9318条查询结果,搜索用时 1 毫秒
51.
BACKGROUND: There is a paucity of information regarding prostate cancer (PCa) risk factors among Hispanics, the fastest-growing ethnic group in the United States. METHODS: This population-based case-control study included 176 Texas men of Mexican descent with PCa and 174 age- and ethnicity-matched controls. Demographic, lifetime occupational history, family history of cancer, lifestyle (e.g., smoking, alcohol, diet, and recreational physical activity) and anthropometric information were collected by personal interviews. Chemical exposure and physical activity were determined using job-exposure matrices for each reported job. RESULTS: Logistic regression models adjusted for relevant covariates were used to evaluate their independent effects. Compared to controls, cases were three times more likely to work in jobs with high agrichemical exposure (OR = 3.44, 95% CI 1.84-6.44), and 54% less likely to work in jobs with moderate/high occupational physical activity (OR = 0.46, 95% CI 0.28-0.77). In analyses stratified by stage, cases with organ-confined PCa were three times more likely to have high agrichemical exposure (OR = 3.39, 9%CI 1.68-6.84), and 56% less likely to have moderate/high levels of occupational physical activity (OR = 0.44, 95% CI 0.26-0.76). Increased risk of being diagnosed with advanced PCa was associated with obesity at time of diagnosis (OR = 2.50, 95% CI 1.20-5.20) and high levels of agrichemical exposure (OR = 4.65, 95% CI 1.97-10.97), but not with occupational physical activity. CONCLUSIONS: This case-control study, the first conducted in a homogeneous Hispanic population, identified modifiable PCa risk factors, such as physical activity and agrichemical exposure, which may be useful in developing interventions for this understudied population.  相似文献   
52.
Objective This study analyzed the clinical and laboratory parameters that might influence the clinical outcomes of patients with type 2 diabetes who develop diabetic ketoacidosis (DKA), which has not been well investigated. Methods We reviewed the clinical and laboratory data of 158 patients who were hospitalized due to DKA between January 2006 and June 2019 and compared the data of patients stratified by the type of diabetes. In addition, the patients with type 2 diabetes were subdivided according to age, and their clinical and laboratory findings were evaluated. Results Patients with type 2 diabetes had a longer symptom duration associated with DKA, higher body mass index (BMI), and higher C-peptide levels than those with type 1 diabetes (p<0.05). Among patients with type 2 diabetes, elderly patients (≥65 years old) had a longer duration of diabetes, higher frequency of DKA onset under diabetes treatment, higher effective osmolarity, lower BMI, and lower urinary C-peptide levels than nonelderly patients (<65 years old) (p<0.05). A correlation analysis showed that age was significantly negatively correlated with the index of insulin secretory capacity. Conclusion Patients with DKA and type 2 diabetes had a higher BMI and insulin secretion capacity than those with type 1 diabetes. However, elderly patients with type 2 diabetes, unlike younger patients, were characterized by a lean body, impaired insulin secretion, and more frequent DKA development while undergoing treatment for diabetes.  相似文献   
53.
The bovine respiratory syncytial virus (BRSV) is an enveloped, negative sense, single-stranded RNA virus belonging to the pneumovirus genus within the family Paramyxoviridae. BRSV has been recognized as a major cause of respiratory disease in young calves since the early 1970s. The analysis of BRSV infection was originally hampered by its characteristic lability and poor growth in vitro. However, the advent of numerous immunological and molecular methods has facilitated the study of BRSV enormously. The knowledge gained from these studies has also provided the opportunity to develop safe, stable, attenuated virus vaccine candidates. Nonetheless, many aspects of the epidemiology, molecular epidemiology and evolution of the virus are still not fully understood. The natural course of infection is rather complex and further complicates diagnosis, treatment and the implementation of preventive measures aimed to control the disease. Therefore, understanding the mechanisms by which BRSV is able to establish infection is needed to prevent viral and disease spread. This review discusses important information regarding the epidemiology and molecular epidemiology of BRSV worldwide, and it highlights the importance of viral evolution in virus transmission.  相似文献   
54.
55.
56.
57.

Background

Salvage esophagectomy is potentially the only treatment available that can offer a chance of long-term survival when definitive chemoradiotherapy (CRT) fails to achieve local control for patients with esophageal squamous cell carcinoma (ESCC). However, salvage esophagectomy is a highly invasive procedure with various postoperative complications compared to planned esophagectomy after neoadjuvant chemoradiotherapy (CRT). We hypothesize that severe postoperative complications may affect not only surgical mortality but also tumor recurrence and long-term survival for patients with salvage esophagectomy after definitive CRT.

Methods

For the present study we reviewed the surgical procedures, postoperative complications, and the prognosis of 65 consecutive patients with thoracic ESCC who underwent the esophagectomy after neoadjuvant (neoadjuvant group: n = 40) or definitive (salvage group: n = 25) CRT.

Results

Most patients underwent right-transthoracic extended esophagectomy and reconstruction using gastric conduit by way of subcutaneous route with left cervical anastomosis. The incidence of postoperative pneumonia was found to be higher in the salvage group than in the neoadjuvant group. In both groups, the survival of patients with R0 resection was significantly better than those with R1/R2 resection. Moreover, in the salvage group, the postoperative survival rate of patients with pneumonia or bacteremia/sepsis was significantly lower than that for patients who did not suffer the same complications. In the neoadjuvant group, R0 resection was selected to be the only independent prognostic factor in univariate and multivariate analysis. In contrast, in the salvage group, R0 resection and bacteremia/sepsis remained significant and were independent of the other factors in multivariate analysis.

Conclusions

This study reveals that postoperative morbidity affects not only the perioperative mortality but also the long-term survival of patients with ESCC who undergo salvage esophagectomy after definitive CRT.  相似文献   
58.
Acute subdural hematoma (ASDH) is a critical condition following the onset of traumatic brain injury, and it is essential to immediately reduce elevated intracranial pressure (ICP). Single burr hole surgery/twist drill craniostomy is commonly performed in patients with ASDH as an emergency surgical intervention, usually preceding decompressive craniotomy. A novel method using a cerebrospinal fluid (CSF) drainage catheter kit for rapid drainage of ASDH is described. Percutaneous twist drill craniostomy using a CAMINO(?) micro ventricular bolt pressure-temperature monitoring kit was performed in the emergency room in 12 patients with severe ASDH. The kit contained a closed-system CSF drainage and pressure-temperature monitoring catheter, which allowed aspiration of the hematoma and monitoring of the ICP. The tip of the catheter was inserted into the hematoma from the forehead. The mean initial ICP was 61 mmHg, with a range of 31 to 120 mmHg. The liquid hematoma was aspirated, and the ICP was temporarily controlled to the normal range. Pupil dilation recovered immediately after aspiration of the hematoma in 3 patients. No complications occurred either during or after the operation. This new method for craniostomy is easy, safe, and effective to monitor and rapidly control ICP in the emergency room. This technique also offers the possibility of evaluating the patient's prognosis and determining indications for further decompressive craniectomy by the continuation of ICP control under ICP monitoring and evaluation of the reversibility of pupillary findings in ASDH patients.  相似文献   
59.
Isolated granulomatous inflammation of the appendix is extremely rare, and its etiology is still unknown. Thus, differentiating between idiopathic granulomatous appendicitis and isolated appendiceal Crohn's disease is difficult. We report a case of idiopathic granulomatous appendicitis with long-term follow-up after surgery. A 26-year-old woman was referred to our hospital for investigation of persistent right lower abdominal pain. Abdominal computed tomography showed a mass, suggesting an inflammatory tumor around the appendix; thus, we suspected subacute appendicitis and performed laparoscopically assisted ileocecal resection. Histological examination of the resected specimen revealed several noncaseous epithelioid granulomas in the wall of the appendix, but no foreign bodies, obstructing lesions, or parasites. Stains for acid-fast bacillus and fungi, and serology for yersinia were all negative. The patient has been followed up for 9 years and remains asymptomatic. This clinical course suggests that her isolated granulomatous appendicitis was idiopathic granulomatous appendicitis unrelated to Crohn's disease.  相似文献   
60.
We examined the effects of chronic salt loading on the hypothalamic expressions of the enhanced green fluorescent protein (eGFP), arginine vasopressin (AVP) and oxytocin (OXT) genes in AVP-eGFP transgenic rats that expressed eGFP in the hypothalamic AVP-containing neurones. In these rats, salt loading for 5 days caused a marked increase of the eGFP fluorescence in the magnocellular divisions of the paraventricular nucleus (PVN), the supraoptic nucleus (SON) and the internal layer of the median eminence. Expression of the eGFP gene was increased seven- to eight-fold in the PVN and SON of salt-loaded rats in comparison with euhydrated rats. By contrast, none of these changes were observed in the suprachiasmatic nucleus. The expression of the AVP and OXT genes was increased 1.5- to two-fold in the PVN and SON of salt-loaded nontransgenic (control) and transgenic rats. There were no differences in the expression levels of the AVP and OXT genes in the PVN and SON between nontransgenic (control) and transgenic animals under normal conditions and after salt loading. In the posterior pituitary gland, the intensity of the eGFP fluorescence did not change after salt loading for 5 days, but increased after 10 days of salt loading. Upon salt loading, significant increases in the plasma AVP concentrations, plasma osmolality and plasma Na+ were observed. Furthermore, there were no significant differences in changes of water intake, food intake, urine volume, urine osmolality, urine Na+ concentrations, and the body weights in both models under normal or salt-loaded conditions. Our results show that the response of the AVP-eGFP fusion gene to chronic salt loading is exaggerated, and humoral responses such as AVP and OXT and the body fluid homeostasis are maintained in AVP-eGFP transgenic rats. The AVP-eGFP transgenic rat gives us a new opportunity to study the dynamics of the AVP system in vivo.  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