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   3251篇
  免费   323篇
  国内免费   78篇
耳鼻咽喉   9篇
儿科学   218篇
妇产科学   69篇
基础医学   370篇
口腔科学   64篇
临床医学   394篇
内科学   787篇
皮肤病学   89篇
神经病学   175篇
特种医学   421篇
外科学   223篇
综合类   84篇
一般理论   3篇
预防医学   358篇
眼科学   36篇
药学   181篇
  2篇
肿瘤学   169篇
  2022年   11篇
  2021年   33篇
  2020年   24篇
  2019年   26篇
  2018年   50篇
  2017年   41篇
  2016年   40篇
  2015年   58篇
  2014年   69篇
  2013年   98篇
  2012年   86篇
  2011年   95篇
  2010年   127篇
  2009年   115篇
  2008年   132篇
  2007年   162篇
  2006年   121篇
  2005年   131篇
  2004年   100篇
  2003年   59篇
  2002年   110篇
  2001年   93篇
  2000年   74篇
  1999年   68篇
  1998年   143篇
  1997年   160篇
  1996年   144篇
  1995年   122篇
  1994年   128篇
  1993年   117篇
  1992年   62篇
  1991年   62篇
  1990年   67篇
  1989年   88篇
  1988年   73篇
  1987年   63篇
  1986年   66篇
  1985年   65篇
  1984年   43篇
  1983年   30篇
  1982年   31篇
  1981年   38篇
  1980年   35篇
  1979年   21篇
  1978年   15篇
  1977年   22篇
  1976年   36篇
  1975年   20篇
  1970年   14篇
  1968年   13篇
排序方式: 共有3652条查询结果,搜索用时 15 毫秒
51.
BACKGROUND: In 1989, skin-sparing mastectomy started at a number of breast centers in the United States because of an increasing demand for immediate reconstruction and a desire for better cosmetic outcomes. METHODS: To ensure the safety of this new approach, we have reviewed the personal series of a single surgeon using a standardized skin-sparing technique during 1989 to 2004. RESULTS: Skin-sparing mastectomy with immediate reconstruction was performed on 225 patients, and standard mastectomy was performed on 1,022 patients. The age distribution was 8 years younger on average in the reconstructed group. The average follow-up for each group was 49 months. The local recurrence for each group was 1.7% and 1.5% (P > .80). The regional recurrence was 3.8% and 3.9% (P > .80). The average time to local recurrence was similar in each group (33.1 and 32.6 months, P > .80). CONCLUSIONS: A skin-sparing mastectomy does not change the local, regional, or systemic risk to breast cancer patients.  相似文献   
52.
53.
54.
BACKGROUND: Breast cancer tumor ablation as part of a multimodality approach in the treatment of breast cancer is the subject of recent interest. This study was conducted to determine if the ability to perform sentinel node biopsy was impaired after thermal-induced ablation of breast cancer. METHODS: We studied patients who had sentinel node biopsy after preoperative focused microwave phased array for breast cancer ablation. RESULTS: Twenty-one patients with T1-T2 breast cancer and clinically negative axilla underwent wide local excision and sentinel node biopsy guided by blue dye and sulfur colloid. Surgery was done an average of 17 days after microwave ablation. Fifteen of 22 patients (68%) had histologic evidence of tumor necrosis. Sentinel lymph node mapping was successful in 19 of 21 patients (91%). Axillary metastases were detected in 42% of cases. CONCLUSIONS: This study documents successful sentinel lymph node mapping for patients treated with antecedent local tumor ablation using focused microwave phased array ablation.  相似文献   
55.
The impact of parathyroidectomy (PTX) on the long-term risks for hip and other fractures is unknown. Uncontrolled case series have reported an increase in bone mineral density after PTX. However, very low serum parathyroid hormone levels have been associated with decreased bone mineral density, adynamic bone disease, and fractures. This study compared long-term fracture rates among hemodialysis patients who underwent PTX with a matched control group. Data were obtained from the US Renal Data System. Patients who underwent a first PTX while receiving hemodialysis were matched with up to three control patients by age, race, gender, year of dialysis initiation, primary cause of renal failure, and the dosage of intravenous vitamin D used before PTX. Patients with a history of fracture or renal transplantation were excluded. Study outcomes were incident hip, vertebral, and distal radius-wrist fractures identified using hospitalization codes. Incident hip fracture rates in the PTX and matched control groups were 6.0 and 9.3 fractures per 1000 person-years, respectively. After adjustment, PTX was associated with a significant 32% lower risk for hip fracture (95% confidence interval 0.54 to 0.86; P = 0.001) and a 31% lower risk for any analyzed fracture (95% confidence interval 0.57 to 0.83; P < 0.001) compared with matched control subjects. Fracture risks were lower among hemodialysis patients who underwent PTX compared with matched control subjects. Surgical amelioration of secondary hyperparathyroidism may outweigh the risk of parathyroid hormone oversuppression in terms of bone health.  相似文献   
56.

Background  

The costs of arm, shoulder and neck symptoms are high. In order to decrease these costs employers implement interventions aimed at reducing these symptoms. One frequently used intervention is the RSI QuickScan intervention programme. It establishes a risk profile of the target population and subsequently advises interventions following a decision tree based on that risk profile. The purpose of this study was to perform an economic evaluation, from both the societal and companies' perspective, of the RSI QuickScan intervention programme for computer workers. In this study, effectiveness was defined at three levels: exposure to risk factors, prevalence of arm, shoulder and neck symptoms, and days of sick leave.  相似文献   
57.
58.
PURPOSE: To compare the bacterial population of the ocular surface of normal and dry eye subjects using conventional culture and 16S rDNA PCR. METHODS: Ninety-one subjects were classified as normal (n = 57) or dry eye (n = 34) by using tear break-up time, McMonnies survey, goblet cell density, and meibomian gland assessment. Conventional bacterial culture and broad-range 16S rDNA PCR, cloning, and DNA sequencing were used for bacterial identification. Repeated sampling was performed in a subset of subjects over a 3-month period. The association between goblet cell loss and bacterial counts in a subgroup of subjects was assessed. RESULTS: Most of the bacteria identified by culture were coagulase negative staphylococci, whereas molecular methods demonstrated a considerable number of additional bacteria. Atypical ocular surface bacteria including Rhodococcus erythropolis, Klebsiella oxytoca, and Erwinia sp., were identified in cases of overt inflammation and, surprisingly, on the normal ocular surface. The same bacteria remained on the ocular surface after repeated sampling. Increased bacterial flora was associated with reduced goblet cell density. CONCLUSIONS: Molecular analysis revealed a diverse ocular surface bacterial population. In addition to the normal flora, various potentially pathogenic bacteria were identified. The detection of known pathogens in both normal and dry eyes, with minimal signs of infection, presents a diagnostic dilemma. It remains unknown whether their presence is associated with inflammation and reduced goblet cell density or whether they adversely affect the ocular surface predisposing it to abnormal microbial colonization. In the absence of overt clinical infection, it is unknown whether such results should prompt intervention with therapy.  相似文献   
59.
The precise biochemical mechanism and site(s) of action by which minoxidil stimulates hair growth are not yet clear. Minoxidil sulfate is the active metabolite of minoxidil, with regard to smooth muscle vasodilation and hair growth. Formation of minoxidil sulfate is catalyzed by specific PAPS-dependent sulfotransferase(s) and minoxidil-sulfating activities have been previously reported to be present in liver and hair follicles. One of these minoxidil-sulfating enzymes has been purified from rat liver (rat minoxidil sulfotransferase, MST) and a rabbit anti-MST antibody has been prepared. Using this anti-MST antibody, we have immunohistochemically localized minoxidil sulfotransferase in the liver and anagen hair follicles from rat. In rat pelage and vibrissa follicles, this enzyme is localized within the cytoplasm of epithelial cells in the lower outer root sheath. Although the immunolocalization of MST might not necessarily correlate with the MST activity known to be present in anagen follicles, the results of this study strongly suggest that the lower outer root sheath of the hair follicle may serve as a site for the sulfation of topically applied minoxidil.  相似文献   
60.
The ileoanal J pouch: radiographic evaluation   总被引:1,自引:0,他引:1  
Hillard  AE; Mann  FA; Becker  JM; Nelson  JA 《Radiology》1985,155(3):591-594
Endorectal ileoanal pull-through offers an attractive alternative to proctocolectomy and ileostomy for patients with ulcerative colitis, Gardner syndrome, and familial polyposis. To our knowledge, a careful radiographic analysis of the ileum, ileal pouch, and ileoanal anastomosis after ileoanal pull-through has not been reported. Thirty-two patients with ulcerative colitis, Gardner syndrome, and familial polyposis underwent colectomy, mucosal proctectomy, and endorectal ileoanal pull-through of a 15-cm ileal "J" pouch and loop ileostomy. Twenty-five (78%) of 32 of all the pouches radiographically demonstrated spiral folds extending from the middle of the pouch to the pectinate line. Other radiographic features included a mesenteric mass effect, pseudopolyps, and a central lucency that indicated intrapouch sutures. Radiographs provide useful information in the postoperative management of the ileal pull-through.  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