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   11085篇
  免费   773篇
  国内免费   66篇
耳鼻咽喉   62篇
儿科学   255篇
妇产科学   302篇
基础医学   1623篇
口腔科学   400篇
临床医学   1043篇
内科学   2253篇
皮肤病学   193篇
神经病学   1370篇
特种医学   325篇
外科学   1269篇
综合类   24篇
现状与发展   1篇
一般理论   8篇
预防医学   1000篇
眼科学   123篇
药学   719篇
中国医学   49篇
肿瘤学   905篇
  2024年   17篇
  2023年   121篇
  2022年   249篇
  2021年   425篇
  2020年   260篇
  2019年   397篇
  2018年   435篇
  2017年   343篇
  2016年   403篇
  2015年   370篇
  2014年   473篇
  2013年   615篇
  2012年   886篇
  2011年   875篇
  2010年   458篇
  2009年   437篇
  2008年   687篇
  2007年   660篇
  2006年   643篇
  2005年   582篇
  2004年   552篇
  2003年   483篇
  2002年   392篇
  2001年   125篇
  2000年   107篇
  1999年   120篇
  1998年   62篇
  1997年   70篇
  1996年   42篇
  1995年   37篇
  1994年   33篇
  1993年   25篇
  1992年   61篇
  1991年   69篇
  1990年   40篇
  1989年   47篇
  1988年   39篇
  1987年   44篇
  1986年   29篇
  1985年   32篇
  1984年   27篇
  1982年   15篇
  1981年   10篇
  1979年   13篇
  1978年   10篇
  1977年   12篇
  1976年   9篇
  1974年   15篇
  1973年   10篇
  1971年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Objective: Generate a list of service guidelines to enable supermarket managers to accommodate the needs of their older customers. Methods: Focus groups and a national telephone survey were conducted with Australian seniors to generate 10 service guidelines for supermarkets. Results: The 10 guidelines produced are considered to be of significant importance by Australian seniors, with some apparent differences in importance and relevance ratings between older and younger seniors, and males and females. Conclusions: Seniors have distinct service preferences when grocery shopping and their needs require special attention in the supermarket environment. In particular, they feel strongly about the quality of staff and equipment with which they come into contact.  相似文献   
12.
13.
The authors studied quality control procedures at human milk banks and nutritional profiles of 909 milk samples (from 195 donors, aged 15 to 45 years) from banked human milk (BHM) in Brasília, Brazil. Number of donations per donor ranged from 1 to > 10 that consisted mostly of mature milk (90.9%) with a mean total energy of 529 +/- 85 kcal/L and a mean total lipid of 22.7 g/L +/- 13.2. Microbiological quality (titrable acidity-Dornic, degrees D) was suitable for infant feeding in 99.2% of samples (< 8 degrees D), ranging from 2 degrees D to 8 degrees D (mean 4.8 +/- 1.4 degrees D). Most BHM (98.1%) samples were dispensed to inpatient infants (1-7 days) diagnosed with respiratory distress (30.1%), prematurity (20.7%), metabolic distress (16.0%), jaundice (14.4%), bacterial infection (6.0%), pneumonia (3.3%), congenital cardiac distress (2.2%), or other conditions (6.2%). Well-motivated mothers and trained staff are serving and sustaining an important life-saving network with long-lasting impact on public health.  相似文献   
14.
BACKGROUND: Retroperitoneal leiomyosarcomas (RLMS) are a challenging clinical entity. The vast majority of patients are operated on when tumors are advanced. We report herein a case of RLMS, mimicking acute appendiceal disease and treated successfully via laparoscopy. METHODS: A 37-year-old woman, para 1, was admitted to our department for right lower quadrant abdominal pain, fever, and leukocytosis. She had no changes in gastrointestinal and urologic function. A physical examination revealed the presence of abdominal guarding, rebound, and a tender mass in the right lower quadrant. The abdominal ultrasound showed an inhomogeneous ovoid mass (6 cm in diameter) located below the cecum, with no definite margins, and consistent with an appendiceal abscess. The patient was referred for laparoscopy. The procedure was performed with the aid of 3 ports: a 12-mm trocar in the umbilicus (open technique), a 10-mm trocar in the left iliac fossa, and a 5-mm one in the supra-pubic space. On inspection of the abdominal cavity, a retroperitoneal 6-cm mass was immediately found below the cecum and the appendix. Neither intraperitoneal seeding nor suspected lymph nodes were present. After dissection of the parietal peritoneum, the mass appeared to be encapsulated and well demarcated from all surrounding structures. It was eventually dissected and removed via a plastic bag. A standard appendectomy was also performed. The postoperative course was uneventful, and the patient was discharged on the 3rd day. The histology analysis of the resected specimen showed a totally excised G2 leiomyosarcoma. The appendix had no signs of inflammation. Postoperatively, the patient underwent a total-body CT-scan, which had no signs of residual or distant disease. No adjuvant therapy was necessary. At an 18-month follow-up, the patient was doing well and was disease free. CONCLUSION: Surgery represents the main therapeutic option for resectable RLMS. Laparoscopy is a useful diagnostic tool that allows safe resection of incidentally discovered, small and well encapsulated RLMS.  相似文献   
15.
In this study, skin-infiltrating cells were characterized in both the active and remission phases of post-burn hypertrophic scar biopstes. Immunohistochemistry examination of active phase samples showed an abundant presence of Langerhans cells, T cells, macrophages, a low presence of natural killer cells and the lack of B lymphocytes. In active hypertrophic scars T lymphocytes infiltrate deep into the superficial dermis and are also observed in the epidermis: CD3+ cells were present at about 222±107 per 0.25 mm2. In particular the analysis of lymphocyte subpopulations showed that CD4+ T cells predominate in the dermis as well as in the epidermis of active hypertrophic scars whereas CD8+ cells were less well represented (CD4/CD8 ratio is 2.06). This distribution was also shown in remission phase samples and in normotrophic scar specimens, although the lymphocyte number was significantly lower. Approximately 70 per cent of T lymphocytes present in the tissue involved in active phase hypertrophic scar samples were activated (positive with anti-HLA-DR and IL-2 receptor antibodies) which is significantly higher than remission phase hypertrophic and normotrophic scars, in which positivity was 40 and 38 per cent, respectively. Upon activation, the lesional lymphocytes release several cytokines, locally and transiently, that interact with specific receptors in response to different stimulation. Central to the immune hypothesis of hypertrophic scars is that some of the T-cell lymphokines act on keratinocytes, fibroblasts and other cell types to induce changes characteristic of these scars. The presence and close proximity of activated T lymphocytes and antigen-presenting cells of various phenotypes in both the epidermis and dermis of hypertrophic tissues provides strong circumstantial evidence of a local immune response. However, the manner in which T cells achieve and maintain their activated state in hypertrophic tissues in not yet known, and both antigen-dependent and independent mechanisms may contribute.  相似文献   
16.
Plasma levels of several soluble factors were assayed in 31 untreated patients with high-grade non-Hodgkin's lymphomas (NHL). The results showed statistically significant higher average levels of interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-2 receptor (IL-2r) and transferrin receptor (TF-r) in NHL patients compared to controls (p = 0.045, p = 0.047, p = 0.020, p = 0.026 and p = 0.033 respectively). IL-2, IL-2r and TF-r levels were found more elevated in Stages III/IV than in Stages I/II (p = 0.031, p = 0.016 and p = 0.048 respectively), whereas IL-6 concentrations were higher in patients presenting B symptoms (p = 0.011). Significant correlations were found between the erythrocyte sedimentation rate (ESR) and IL-6 (r = 0.681), and between beta 2 microglobulin (B2-m) and IL-2r (r = 0.622).  相似文献   
17.
Neurological Sciences - The diagnostic pathway in a patient with vertigo starts with the accurate evaluation of medical history followed by a general physical and neurological examination. This...  相似文献   
18.
19.
OBJECTIVE: To quantify the clinical impact of methicillin-resistance in Staphylococcus aureus causing infection complicated by bacteremia in adult patients, while controlling for the severity of patients' underlying illnesses. DESIGN: Retrospective cohort study from October 1, 1995, through December 31, 2003. PATIENTS AND SETTING: A total of 438 patients with S. aureus infection complicated by bacteremia from a single Veterans Affairs healthcare system. RESULTS: We found that 193 (44%) of the 438 patients had methicillin-resistant S. aureus (MRSA) infection and 114 (26%) died of causes attributable to S. aureus infection within 90 days after the infection was identified. Patients with MRSA infection had a higher mortality risk, compared with patients with methicillin-susceptible S. aureus (MSSA) infections (relative risk, 1.7 [95% confidence interval, 1.3-2.4]; P<.01), except for patients with pneumonia (relative risk, 0.7 [95% confidence interval, 0.4-1.3]). Patients with MRSA infections were significantly older (P<.01), had more underlying diseases (P=.02), and were more likely to have severe sepsis in response to their infection (P<.01) compared with patients with MSSA bacteremia. Patients who died within 90 days after S. aureus infection was identified were significantly older (P<.01) and more likely to have severe sepsis (P<.01) and pneumonia (P=.01), compared with patients who survived. After adjusting for age as a confounder, comorbidities, and pneumonia as an effect modifier, S. aureus infection-related mortality remained significantly higher in patients with MRSA infection than in those with MSSA infection, among those without pneumonia (hazard ratio, 1.8 [95% confidence interval, 1.2-3.0]); P<.01. CONCLUSIONS: The results of this study suggest that patients with MRSA infections other than pneumonia have a higher mortality risk than patients with MSSA infections other than pneumonia, independent of the severity of patients' underlying illnesses.  相似文献   
20.
The association between IUD use and the occurrence of pelvic infections caused by actinomyces was investigated in 221 IUD users at a University of Turin clinic. Pelvic actinomycosis is chronic and progressive, and diagnostic error and/or inappropriate treatment often lead symptoms to persist for years. Each study participant had a Papanicolaou smear both before IUD insertion and during IUD use. No Pap smear was positive for actinomyces before IUD insertion; however, during IUD use, this microorganism was identified in 30 patients (14%). There was no correlation between infection and socioeconomic status, a history of prior abortion, or IUD size. There was no significant difference between infection rates in nulliparae (12%) and primiparae (14%). Infection was found in 8% of Papanicolaou class I patients and in 15% of class II subjects. The mean duration of IUD use in women with positive Actinomyces vaginal smears was 32.1 months compared with 23.2 months for patients with negative findings. Finally, the risk of infection was higher among acceptors of plastic rather than copper IUDs. These findings confirm the association between IUD use and pelvic actinomycosis; a review of the literature reveals 395 such cases. When actinomycotic infection is discovered, immediate removal of the IUD is necessary and targetted antibiotic treatment should be commenced.  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