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   6870篇
  免费   424篇
  国内免费   23篇
耳鼻咽喉   98篇
儿科学   626篇
妇产科学   116篇
基础医学   858篇
口腔科学   132篇
临床医学   441篇
内科学   1421篇
皮肤病学   304篇
神经病学   349篇
特种医学   326篇
外科学   672篇
综合类   181篇
一般理论   3篇
预防医学   403篇
眼科学   245篇
药学   564篇
中国医学   24篇
肿瘤学   554篇
  2023年   50篇
  2022年   123篇
  2021年   227篇
  2020年   164篇
  2019年   193篇
  2018年   222篇
  2017年   141篇
  2016年   163篇
  2015年   176篇
  2014年   297篇
  2013年   335篇
  2012年   460篇
  2011年   442篇
  2010年   271篇
  2009年   215篇
  2008年   305篇
  2007年   315篇
  2006年   301篇
  2005年   280篇
  2004年   256篇
  2003年   219篇
  2002年   195篇
  2001年   148篇
  2000年   125篇
  1999年   120篇
  1998年   70篇
  1997年   42篇
  1996年   48篇
  1995年   33篇
  1994年   44篇
  1993年   41篇
  1992年   87篇
  1991年   93篇
  1990年   96篇
  1989年   84篇
  1988年   71篇
  1987年   81篇
  1986年   60篇
  1985年   61篇
  1984年   65篇
  1983年   47篇
  1982年   64篇
  1981年   75篇
  1980年   72篇
  1979年   55篇
  1978年   33篇
  1977年   26篇
  1976年   34篇
  1973年   31篇
  1970年   26篇
排序方式: 共有7317条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: Early prediction of response to therapy may offer the potential to identify patients who will benefit from standard conventional therapy. The objective of this study was to determine the predictive value of FDG-PET as an early response indicator after 1 cycle of chemotherapy for progression-free survival (PFS) in diffuse large cell lymphoma (DLCL) and classic Hodgkin disease (HD). METHODS: FDG-PET was performed before, after 1 cycle, and after completion of chemotherapy in 47 patients. The patients were followed with a median follow-up of 21 months (range, 3-47 months). PFS was compared between PET-positive and PET-negative patients after 1 cycle and after completion of therapy. RESULTS: All PET-negative patients after 1 cycle (n = 31) had sustained complete remission with a median follow-up of 28 months. Fourteen of 16 PET-positive patients after 1 cycle had refractory disease or relapsed (median PFS, 5.5 months). There were 2 false-positive results, 1 with an active infection at the biopsy site and the other in a patient who had been in remission after radiation therapy. There was good agreement between the results obtained after 1 cycle and at completion of therapy (kappa, 0.80); however, the negative predictive value was higher for FDG-PET after 1 cycle than after completion of chemotherapy (100% vs 91.4%), although not statistically different (P = .40). CONCLUSIONS: FDG-PET had a high prognostic value after 1 cycle of chemotherapy, thus it can be a valid alternative for posttreatment evaluation of DLCL and HD and may offer the potential for change in treatment paradigms.  相似文献   
992.
The concentrations and patterns of polychlorinated biphenyls (PCBs), chlorinated pesticides, and polybrominated diphenyl ethers (PBDEs) were studied in white whales (Delphinapterus leucas) and narwhals (Monodon monoceros) from Svalbard, Norway. In addition, their main food items were included in the study. In the whales, a broad range of pollutants was found in relatively high concentrations. PCBs and pesticides were approximately 3000 and 8000 ng/g lipid, respectively, for white whales and three times higher for narwhals. PBDEs 47 were approximately 70 ng/g lipid for white whales and 170 ng/g lipid for narwhals. Compared with other marine mammals from the same area, contaminant levels are among the highest levels ever measured. These high levels are likely in part because of a decreased capacity to metabolize contaminants. Metabolic indices indicated that most compounds accumulate to the same degree in white whales and narwhals, but for some toxaphenes and chlordanes, narwhals might have a decreased metabolism and consequently a higher accumulation. The three-times-higher contaminant levels in blubber of narwhals was further explained by substantially higher contaminant levels in their more benthic diet. The high levels and broad pattern of accumulating pollutants make white whales and narwhals excellent indicators for a wide range of contaminants in the Arctic.  相似文献   
993.
Vaginismus is a sexual dysfunction in which spasm of vaginal musculature precludes penetrative intercourse. In many cases associated pain or fear of pain may contribute to the maintenance of vaginismus. We report a case of primary vaginismus with associated pain that benefited from topical application of lignocaine gel along with systematic desensitization resulting in successful consummation, and suggest that it may be a useful adjunct during finger dilatation in the treatment of vaginismus, specifically in patients who have associated pain or areas of hyperesthesia in the introitus.  相似文献   
994.
Laparoscopic surgery is an established treatment modality for adrenal disease, especially pheochromocytomas. We describe the successful excision of an extra-adrenal pheochromocytoma using a novel transperitoneal, transmesocolic approach. The tumor was located inferior to the left renal hilum in the para-aortic region and was found bulging through the descending mesocolon at laparoscopy. The tumor was removed without mobilization of the descending colon.  相似文献   
995.
996.
Patients with peripheral arterial disease (PAD) are at a markedly higher risk of cardiovascular morbidity and mortality, with evidence indicating that risk-reduction pharmacotherapy can serve to attenuate cardiovascular events in these patients. Given the central role of vascular surgeons in the treatment of patients with PAD, we sought to determine their perceptions and knowledge of risk-reduction pharmacotherapy in patients with PAD. We conducted a cross-sectional survey of 79 Canadian vascular surgeons who attended the 2004 annual meeting of the Canadian Society for Vascular Surgery, the largest and most representative meeting of its kind in Canada. The recommended targets of low-density lipoprotein cholesterol, blood glucose, and blood pressure were known to 53.8%, 40.4%, and 57.7% of vascular surgeons, respectively. The majority of vascular surgeons (65.4%) reported screening for risk factors in <50% of cases. Although 90.4% of vascular surgeons would recommend antiplatelet therapy for PAD, only 5.8% would recommend angiotensin converting enzyme (ACE) inhibitors and 19.2% would recommend lipid-lowering therapy with statins. Eighty-four percent of Canadian vascular surgeons indicated that their self-assessment of risk reduction in PAD was average to below average, yet 90.4% of them believed that risk-reduction therapy should be recommended or initiated by vascular surgeons. Canadian vascular surgeons’ perceptions toward risk reduction in PAD identify knowledge and action gaps, despite the recognition that recommending and instituting therapy is important to patient care. Given the heightened risk of cardiovascular disease in patients with PAD, these data have important implications. Presented at the Twenty-seventh Annual Meeting of the Canadian Society for Vascular Surgery, Toronto, Ontario, Canada, September 9-10, 2005.  相似文献   
997.
Basson MD  Butler TW  Verma H 《Anesthesiology》2006,104(4):826-834
BACKGROUND: Previous attempts at improving operating room utilization have generally emphasized more accurate scheduling, starting the first case on time, and reducing turnover time. Surgical case cancellations have largely been ignored except for recommendations for preoperative screening and good physician-patient communication to improve patient compliance. METHODS: A retrospective review of operating room records was initially used to identify reasons for surgical cancellations. This was followed by a retrospective stratified case-control study of patient records to identify preexisting factors that predict the failure of patients to appear for surgical procedures as scheduled. Factors assessed included demographics, type of surgical procedure, compliance with previous healthcare visits, substance abuse, mental illness, travel distance, and neurologic problems. RESULTS: The authors reviewed their operating room utilization and found patient nonappearance rates to be a substantial source of surgical cancellations. Furthermore, multivariate analysis demonstrated that patient nonappearance could be strongly predicted from patient noncompliance with clinic visits and other clinical procedures without reference to the other variables assessed. Further analysis of data from an independent sample of patients confirmed this observation. CONCLUSIONS: Noncompliance with hospital visits for surgical procedures can be predicted from noncompliance with other healthcare encounters. Surgical procedures for previously noncompliant patients should be booked at the end of the operating room day, when the cancellation is least likely to interfere with operating room flow.  相似文献   
998.
999.
OBJECTIVES: To examine nationally representative data and thus obtain estimates of the use of healthcare providers associated with the overactive bladder (OAB) symptoms, a condition characterized by frequency, urgency and nocturia, with or with no urge incontinence, as although it is ranked among the 10 most common chronic medical conditions in the USA, the level of OAB-associated medical treatment remains largely unknown. METHODS: To estimate the number of annual OAB-associated medical visits among patients aged > or =18 years, three national databases in the USA (year 2000) were examined: the National Ambulatory Medical Care Survey, the National Hospital Ambulatory Medical Care Survey, and the National Hospital Discharge Survey. Population estimates were constructed using design-based statistical analyses to account for the complex survey designs of data. RESULTS: During 2000, adult Americans made 1.4 million (95% confidence interval 1.1-1.8 million) ambulatory visits to non-Federal office-based physicians with International Classification of Disease (ICD-9) coding indicative of OAB symptoms. Accounting for emergency and outpatient department visits, as well as non-Federal short-stay hospital discharges, the estimated number of medical visits with OAB-associated ICD-9 coding was <1.5 million. CONCLUSION: The prevalence of OAB was estimated to be 34 million adult Americans. When 1.4 million ambulatory visits were compared with this prevalence, as few as 4% of adult Americans with OAB sought medical treatment during the year 2000. The present results therefore suggest a large unmet medical need among the population of adult Americans with OAB.  相似文献   
1000.
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