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   375339篇
  免费   43916篇
  国内免费   3211篇
耳鼻咽喉   7242篇
儿科学   11065篇
妇产科学   6658篇
基础医学   32049篇
口腔科学   5711篇
临床医学   49037篇
内科学   93380篇
皮肤病学   10428篇
神经病学   37317篇
特种医学   15938篇
外国民族医学   13篇
外科学   75355篇
综合类   2753篇
现状与发展   73篇
一般理论   177篇
预防医学   23108篇
眼科学   8651篇
药学   16273篇
  1篇
中国医学   325篇
肿瘤学   26912篇
  2024年   785篇
  2023年   5806篇
  2022年   3275篇
  2021年   8137篇
  2020年   8642篇
  2019年   7000篇
  2018年   12927篇
  2017年   11269篇
  2016年   12655篇
  2015年   13521篇
  2014年   22833篇
  2013年   25813篇
  2012年   22236篇
  2011年   23011篇
  2010年   19710篇
  2009年   22584篇
  2008年   21195篇
  2007年   20299篇
  2006年   22186篇
  2005年   19473篇
  2004年   17789篇
  2003年   15559篇
  2002年   15063篇
  2001年   5497篇
  2000年   4250篇
  1999年   5032篇
  1998年   6202篇
  1997年   5484篇
  1996年   5079篇
  1995年   4789篇
  1994年   3349篇
  1993年   2963篇
  1992年   2276篇
  1991年   2252篇
  1990年   1793篇
  1989年   1861篇
  1988年   1641篇
  1987年   1422篇
  1986年   1479篇
  1985年   1353篇
  1984年   1421篇
  1983年   1277篇
  1982年   1521篇
  1981年   1347篇
  1980年   1178篇
  1979年   752篇
  1978年   832篇
  1977年   825篇
  1976年   638篇
  1975年   583篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Despite decreasing mortality rates, morbidity is still high after pancreatic head resection. Comparative data in the United States and Europe show a relationship between hospital volume and mortality. Treatment strategies vary frequently, partially because of the lack of evidence-based data. We performed a multi-institutional analysis in Germany evaluating current numbers, indications, techniques, and complication rates of pancreatic head resection. Questionnaires were completed by seven high-volume surgical departments regarding quantitative and qualitative aspects of pancreatic head resections in the period from 1999 to 2004 (five prospective and two retrospective institutional databases). A total of 1454 pancreatic head resections (944 for malignancy) were reported. Mean annual hospital volume ranged from 14 to 52 (10 to 43 in malignancy). Mortality was between 1.1% and 4.8%, morbidity was between 24% and 46%, and pancreatic leakage was between 9% and 20%. In malignant disease, all centers perform standard lymphadenectomy and regard arterial infiltration as a contraindication for resection. However, the rate of portal vein resection varied from 0% to 28%. No consensus is seen on the type of surgery for malignancy and chronic pancreatitis. After resection for pancreatic cancer less than one fourth of the patients receive adjuvant therapy. The results of our analysis in Germany confirm that pancreatic head resection can be performed with low mortality in specialized units. Variations in indications, operative technique, and perioperative care may demonstrate the lack of evidence-based data and/or personal and institutional experience. The low number of patients receiving adjuvant therapy after resection of pancreatic cancer suggests that more efforts must be made to establish novel adjuvant therapies under randomized study conditions. Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18, 2005 (oral presentation).  相似文献   
992.
993.
OBJECTIVE: To compare the efficacy, safety, and duration of effect of four doses of botulinum toxin type A in the treatment of glabellar rhytids in females. DESIGN: Double-blind, randomized, parallel-group, dose-ranging trial followed by an open-label extension. SETTING: Private dermatologic clinic. SUBJECTS: Eighty female subjects with moderate to severe wrinkles at maximum frown entered the study. The first 40 subjects completing the double-blind phase entered the open-label extension. INTERVENTION: Random administration of 10, 20, 30, or 40 U botulinum toxin type A in divided doses. Open-label trial: 30 U botulinum toxin type A at the same sites in divided doses. MAIN OUTCOME MEASUREMENTS: Trained observer and subject assessments of wrinkle severity at maximum frown and repose using the Facial Wrinkle Scale (0 = none to 3 = severe), subject satisfaction, and adverse events. Follow-up monthly for up to 1 year postinjection. RESULTS: Relapse rates and responder rates revealed benefits lasting 3 to 6 months or longer. Objectively, 10 U of botulinum toxin type A was significantly less effective than 20, 30, or 40 U. The relapse rate at 4 months was significantly higher in the 10 U group (83%) versus 40, 30, or 20 U (28%, 30%, and 33%, respectively). Subject satisfaction was high in all groups. Duration of effect and response rates were sustained during the open-label extension. Adverse effects were mild and infrequent. CONCLUSION: Twenty to 40 U botulinum toxin type A doses were significantly more effective at reducing glabellar lines than 10 U. Most subjects experienced benefits for 3 to 4 months; some subjects demonstrated effect for up to 12 months.  相似文献   
994.
995.
996.
R. Steven Singer  MD 《Headache》2004,44(6):626-626
  相似文献   
997.
Background. For several years, magnification has been used to separate follicular groupings from donor strips to minimize transection of hair follicles. There has been no discussion regarding the use of magnification to create recipient sites to limit transection of existing hair follicles in recipient zones.
Objective. The study was performed to evaluate the role of magnification when creating hundreds or thousands of recipient sites in patients with existing hair.
Methods. A 2× magnified polarized light-emitting diode (LED) for graft and recipient site creation (Syris Scientific, Gray, Maine) was used in 75 consecutive male and female patients. A team of four experienced surgical assistants and the author evaluated the device for graft creation, recipient site creation, and insertion of grafts.
Results. There was no perceived advantage in creating grafts or placing grafts compared with other magnification devices and traditional methods. There was less eye strain and greater ease in creating recipient sites using polarized magnification compared with traditional surgical lights and no magnification.
Conclusion. In an era of medications that slow or stop hair loss, magnification in recipient sites can reduce transection of existing hair follicles in recipient zones, leading to maximum density from a procedure. Further studies are needed to confirm the reduced transection rate of hair follicles and determine the ideal magnification. The use of magnification with LED polarized light in the recipient zone is an important new tool in hair transplant.  相似文献   
998.
BACKGROUND: The results from four phase III, randomized, vehicle-controlled studies showed that imiquimod 5% cream (imiquimod) was safe and effective in the treatment of actinic keratosis (AK). Patients applied imiquimod or vehicle cream to AK lesions on the face or balding scalp, dosing three times per week or two times per week for 16 weeks. OBJECTIVE: To obtain long-term safety follow-up data and estimate AK recurrence in patients who completely cleared their AK lesions in the treatment area at the 8-week post-treatment visit in the phase III studies. METHODS: One hundred forty-six patients from 30 study centers in the United States were evaluated for clinical evidence of AK, and safety data were collected. RESULTS: After a median follow-up period of 16 months, 24.7% (19 of 77) of the patients administered imiquimod three times per week and 42.6% (23 of 54) of the patients administered imiquimod two times per week had a recurrence of AK (the appearance of at least one AK lesion) in the original treatment area. The median number of AK lesions present was one lesion for both patients receiving imiquimod three times and those receiving imiquimod two times per week compared with a median of six lesions at baseline in the combined three times per week and two times per week phase III studies. There were no long-term safety issues, and the skin quality seen in the imiquimod-treated patients at the end of the phase III studies was maintained. CONCLUSION: One and a half years following treatment, imiquimod continued to provide a long-term clinical benefit in a majority of patients who experienced complete clearance of their AK lesions.  相似文献   
999.
1000.
BACKGROUND: Twenty subjects were treated with either polidocanol (POL) or sodium tetradecyl sulfate (STS) to compare the efficacy and adverse sequelae of each agent. OBJECTIVE: To determine the safety and efficacy of two widely used sclerosing agents. METHODS: After the exclusion of saphenofemoral junction incompetency, each subject's leg veins were categorized by size (< 1, 1-3, and 3-6 mm in diameter). Each leg was then randomized to be treated with 0.5%, 1%, or 1% foam of POL or 0.25%, 0.5%, or 0.5% foam of STS according to vein size. An independent panel of four physicians, blinded to treatment, performed randomized photographic evaluations obtained pretreatment and 12 weeks post-treatment. Subject satisfaction index and overall clinical improvement assessment were also obtained. RESULTS: An average 83% improvement was noted for all vein sizes in all subjects with both POL and STS after a single treatment. Subjects were satisfied with treatment, regardless of the sclerosing agent used or the vein size treated. There was no statistically significant difference in adverse effects between each group. CONCLUSION: Both POL and STS are safe and effective sclerosing agents in the treatment of varicose and telangiectatic leg veins. Both are very tolerable and demonstrate similar post-treatment sequelae.  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