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   8296篇
  免费   621篇
  国内免费   28篇
耳鼻咽喉   123篇
儿科学   241篇
妇产科学   179篇
基础医学   1040篇
口腔科学   176篇
临床医学   1002篇
内科学   1721篇
皮肤病学   119篇
神经病学   825篇
特种医学   383篇
外科学   1367篇
综合类   58篇
一般理论   3篇
预防医学   540篇
眼科学   114篇
药学   439篇
中国医学   37篇
肿瘤学   578篇
  2023年   46篇
  2022年   53篇
  2021年   184篇
  2020年   115篇
  2019年   178篇
  2018年   219篇
  2017年   173篇
  2016年   174篇
  2015年   228篇
  2014年   310篇
  2013年   361篇
  2012年   576篇
  2011年   580篇
  2010年   329篇
  2009年   296篇
  2008年   516篇
  2007年   535篇
  2006年   518篇
  2005年   531篇
  2004年   586篇
  2003年   511篇
  2002年   439篇
  2001年   47篇
  2000年   61篇
  1999年   71篇
  1998年   105篇
  1997年   96篇
  1996年   78篇
  1995年   82篇
  1994年   68篇
  1993年   56篇
  1992年   51篇
  1991年   37篇
  1990年   30篇
  1989年   39篇
  1988年   30篇
  1987年   28篇
  1986年   34篇
  1985年   35篇
  1984年   47篇
  1983年   43篇
  1982年   52篇
  1981年   51篇
  1980年   45篇
  1979年   24篇
  1978年   33篇
  1977年   38篇
  1976年   21篇
  1973年   32篇
  1972年   17篇
排序方式: 共有8945条查询结果,搜索用时 15 毫秒
31.
A horizontal double skin island pectoralis major myocutaneous flap with preservation of nipple-areola complex is described, a different modification used to reconstruct a complex defect following radical resection of a locally advanced gingival carcinoma. The skin islands are horizontally separated by a distance of 2.5 cm but rely on one vascular pedicle for their blood supply. The muscle between the skin islands provides the soft tissue bulk between the internal mucosal and external skin lining. The need for a separate segmental flap or a split-thickness skin graft for mucosal lining was eliminated.  相似文献   
32.
The objective of the work was to identify changes in antidepressant drug use and determine if the prevalence of antidepressant use has changed over 14 years. A longitudinal analysis comparing antidepressant drug use at 14 yearly intervals from 1978–79 to 1991–92 was undertaken using the longitudinal health screening program of ambulatory elderly participants (Florida Geriatric Research Program). Participants included all subjects screened in the Florida Geriatric Research Program from 1 August 1978 to 31 July 1992. The outcome measures were self-reported antidepressant drug use. Approximately 3.0 per cent (range of 2.3 to 3.2 per cent over 14 yearly intervals) of participants in this program reported the use of an antidepressant drug. There was no statistically significant change in antidepressant use between 1978–79 and 1991–92 (p > 0.6630). Across all study intervals women reported more frequent use of antidepressant drugs than men. In 1991–92, amitriptyline and imipramine represented over 50 per cent of all antidepressant drug use in this elderly population. Less than 6 per cent of all antidepressant drug use was for fluoxetine, the newest selective serotonin uptake inhibitor. The majority of elderly patients are receiving older tertiary amine tricyclic antidepressants such as amitriptyline, imipramine and doxepin that are not the preferred drugs for the elderly. Educational programs are needed to improve antidepressant prescribing for geriatric patients.  相似文献   
33.
Chlamydia screening in primary care   总被引:1,自引:0,他引:1  
  相似文献   
34.
35.
36.
Oxygen free radicals (OFR) are implicated in thepathogenesis of stress, chemically induced gastriclesions, and gastrointestinal injury. Theconcentration-dependent scavenging abilities of bismuthsubsalicylate (SBS), colloidal bismuth subcitrate (CBS), andselected OFR scavengers, including superoxide dismutase(SOD), catalase, mannitol, and allopurinol were examinedagainst biochemically or chemically generated superoxide anion, hydroxyl radical, andhypochlorite radical plus hypochlorous acid based on achemiluminescence assay. Furthermore, both gastric (GM)and intestinal mucosa (IM) were individually exposed in vitro to these free radical generatingsystems, and the concentration-dependent protectiveabilities of SBS and CBS against lipid peroxidation (LP)were compared with selected OFR scavengers. In addition, 24-hr fasted rats were orally treated with thenecrotizing agents 0.6 M HCl, 0.2 M NaOH, 80% ethanol,and aspirin (200 mg/kg). The extent of tissue injury inthe GM and IM was determined by assessing LP, DNA fragmentation, and membrane microviscosity.Dose- and time-dependent in vivo protective abilities ofCBS (100 mg/kg) and SBS (15 mg/kg) were also assessed.Following incubations with superoxide anion and hydroxyl radical generating systems in thepresence of 125 mg SBS/liter, approximately 47% and 61%inhibitions were observed in the chemiluminescenceresponse, respectively, while 48% and 46% inhibitions were observed with 125 mg CBS/liter. SBS andCBS exerted similar abilities towards hypochloriteradical plus hypochlorous acid. Approx. 3.1- and3.7-fold increases in LP were observed in the GM and IMof rats following oral administration of 0.6 MHCl. Pretreatment of the rats with SBS and CBS decreased0.6 M HCl-induced LP in the GM by approx. 39% and 27%,respectively, with similar decreases in LP in the IM. SBS exhibited better protectiveabilities towards 0.6 M HCl and 0.2 m NaOH-induced GMand IM injury as compared to CBS. SBS and CBS providedsimilar protection towards 80% ethanol-induced gastric injury, while CBS exerted a superior protectiveability towards aspirin-induced gastric injury. Theresults demonstrate that both SBS and CBS can scavengereactive oxygen species and prevent tissue damage produced by OFR.  相似文献   
37.
Abstract. Medical and social problems related to alcohol use are frequently seen in the ED. Often, the tempo of emergency medicine practice seems to preclude assessment beyond that required by the acute complaint. However, detection of ED patients with alcohol problems can occur using brief screening tools. This article was developed by members of the SAEM Substance Abuse Task Force, and describes screening tools that have been used successfully to identify atrisk and dependent drinkers. Their brevity, reproducibility, and accuracy vary somewhat, but screening can be realistically performed in the busy ED setting. The early detection of patients with alcohol problems would provide the opportunity for early intervention, and may reduce subsequent morbidity and mortality in this patient population.  相似文献   
38.
Teaching children about skin cancer prevention: why wait for adolescence?   总被引:1,自引:0,他引:1  
Abstract: The baseline knowledge about skin cancer prevention of 983 children aged 8 to 12 years was assessed by a pretest questionnaire. After the pretest, half were given a formal presentation about skin cancer prevention. The other half participated in an informal, question–and–answer session, which covered all material from the formal presentation. Two weeks later, all students completed an identical post–test. The students had a high baseline level of knowledge about skin cancer prevention. Knowledge increased for most items in the post–test questionnaire. In all age groups there was no difference in results between the formal and interactive teaching sessions, except among eight–year–olds, for whom the formal presentation was more effective. As much solar skin damage occurs before adolescence, the younger age group is the important target for skin cancer prevention programs. (Aust N Z J Public Health 1997; 21: 602–5)  相似文献   
39.
Summary Oxygen is thought to be involved both directly and indirectly in the mechanisms of action of several anticancer agents. We studied the effects of various oxygen concentrations on the cytotoxicities of the following drugs: bleomycin (BLM), etoposide (VP-16), doxorubicin (DOX), and mitomycin C (MMC). Human sarcoma cells, MESSA, were exposed to drug for 1 h at one of several oxygen concentrations: less than 1%, 2.5%, 5%, 21%, and 95%. Cytotoxicity was assessed by cellular incorporation of 3H-thymidine into DNA 5 days after drug exposure. Control experiments varying oxygen concentration without drugs demonstrated toxicity only at the highest concentration (95%). Three different responses of drug sensitivity to varying oxygen tensions were observed. BLM, which has been shown to utilize oxygen as a substrate in generating free radicals and producing DNA scission, demonstrated a progressive increase in cytotoxicity over the entire range of increasing oxygen concentrations. This is consistent with the model of a BLM-cation-oxygen complex and catalytic reduction of oxygen. VP-16, which also produces DNA strand breakage but by interaction with topoisomerase II, exhibited a threshold response. VP-16 toxicity was ameliorated by anoxic conditions (less than 1% O2), but not by oxygen concentrations of 2.5%–95%. The reason for this protective effect of anoxia with VP-16 is not clear. In contrast, acute anoxia had no effect on the cytotoxicities of DOX and MMC. We conclude that acute hypoxia protects cells from both BLM and VP-16 but that the nature of that protection is different. VP-16 toxicitiy is blunted only by severe anoxia, wheaeas BLM exhibits a dose response effect over the entire range of oxygen concentrations.Supported by NIH grant CA-27478 from the US Department of Health and Human Services, and by the American Lung Association. Dr. Sikic is a recipient of a Faculty Development Award in Clinical Pharmacology from the Pharmaceutical Manufacturer's Association Foundation.  相似文献   
40.
Thrombosis of the cerebral dural venous sinuses, cortical draining veins, and deep cerebral veins is a rare clinical finding. Because of its low incidence and multiple etiologies, the optimum therapy for this condition will only be elucidated by a multicenter, randomized prospective study. At our institution, we favor early and aggressive management of cerebral venous sinus thrombosis with transfemoral, venous intradural infusions of the fibrinolytic agent urokinase. To date, treatment of only 13 patients using this technique has been reported in the English literature. This report adds 12 more such treated patients. Despite the presence of preinfusion infarcts in 5 patients, four of which were hemorrhagic, we incurred no major therapeutic morbidity. Functional sinus patency was achieved in 11 of 12 patients, with our only true failure occurring in an individual with symptoms of at least 2 months' duration. Good to excellent clinical outcome was achieved in 10 of 11 patients (one newborn had inadequate follow-up).  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