全文获取类型
收费全文 | 3851634篇 |
免费 | 280185篇 |
国内免费 | 9892篇 |
专业分类
耳鼻咽喉 | 53245篇 |
儿科学 | 125629篇 |
妇产科学 | 105799篇 |
基础医学 | 541046篇 |
口腔科学 | 108782篇 |
临床医学 | 351827篇 |
内科学 | 749790篇 |
皮肤病学 | 86896篇 |
神经病学 | 315858篇 |
特种医学 | 149610篇 |
外国民族医学 | 1227篇 |
外科学 | 579010篇 |
综合类 | 84797篇 |
现状与发展 | 6篇 |
一般理论 | 1527篇 |
预防医学 | 305231篇 |
眼科学 | 87578篇 |
药学 | 281604篇 |
11篇 | |
中国医学 | 7550篇 |
肿瘤学 | 204688篇 |
出版年
2018年 | 41632篇 |
2017年 | 32008篇 |
2016年 | 36467篇 |
2015年 | 41130篇 |
2014年 | 57630篇 |
2013年 | 87563篇 |
2012年 | 116014篇 |
2011年 | 123493篇 |
2010年 | 74577篇 |
2009年 | 71094篇 |
2008年 | 115541篇 |
2007年 | 122872篇 |
2006年 | 124690篇 |
2005年 | 120580篇 |
2004年 | 116049篇 |
2003年 | 111931篇 |
2002年 | 108196篇 |
2001年 | 177868篇 |
2000年 | 182609篇 |
1999年 | 154491篇 |
1998年 | 45565篇 |
1997年 | 40377篇 |
1996年 | 40624篇 |
1995年 | 39175篇 |
1994年 | 36335篇 |
1993年 | 34129篇 |
1992年 | 122236篇 |
1991年 | 118258篇 |
1990年 | 114804篇 |
1989年 | 110794篇 |
1988年 | 102065篇 |
1987年 | 100293篇 |
1986年 | 94801篇 |
1985年 | 90723篇 |
1984年 | 68348篇 |
1983年 | 58142篇 |
1982年 | 34949篇 |
1981年 | 31284篇 |
1979年 | 61909篇 |
1978年 | 44144篇 |
1977年 | 37285篇 |
1976年 | 34824篇 |
1975年 | 37333篇 |
1974年 | 44544篇 |
1973年 | 42612篇 |
1972年 | 40012篇 |
1971年 | 37098篇 |
1970年 | 34426篇 |
1969年 | 32790篇 |
1968年 | 30290篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
Multiple intrahippocampal injections of gallamine impair performance of a representational memory task in rats. The binding of [3H]-(-)-quinuclidinyl benzilate (QNB) to rat brain sections was measured to determine if changes in receptor binding were associated with the deleterious effects of gallamine. [3H]-(-)-QNB binding to sections taken from gallamine-injected animals was compared with binding in saline-injected control animals. Autoradiographic analyses indicated an increase in [3H]-(-)-QNB binding sites within all layers of the cerebral cortex and in the superior colliculus in gallamine-treated animals as compared to saline-injected controls. Significant increases were noted in cortical layers IV and V (P less than 0.025) in gallamine-treated animals. No significant changes (P greater than 0.05) in the number of binding sites were observed in the hippocampus, neostriatum or various thalamic nuclei. The ability of unlabeled pirenzepine, gallamine and carbamylcholine to inhibit 0.2 nM [3H]-(-)-QNB binding also was measured to determine changes in the distribution of receptor subtypes. No significant changes were observed in any brain region for the binding of the selective antagonists pirenzepine and gallamine or the agonist carbamyl-choline. Although other possibilities are considered, the data suggest that an increase in the number of muscarinic receptors may contribute to the observed behavioral deficits associated with long-term gallamine treatment. 相似文献
992.
Janet M Powell Sonya L Griffith Elizabeth M Kanny 《The American journal of occupational therapy》2005,59(4):467-474
PURPOSE: To provide a model for assessing occupational therapy workforce needs by using a demand-based approach to determine current workforce status in the Northwest region. Regional information may have implications for addressing national occupational therapy service needs. METHOD: A questionnaire was sent to a proportional random sample of 234 facilities that hire occupational therapy practitioners. Data were collected in July-August 2003 using structured mailing and follow-up procedures. RESULTS: Response rate was 79%. Twenty-four percent reported occupational therapy vacancies and 11% occupational therapy assistant vacancies; 48% predicted an increase in occupational therapy positions in the next 2 years and 41% an increase in occupational therapy assistant positions. Sixty-three percent of respondents reported difficulty in hiring. DISCUSSION: This study identifies an occupational therapy workforce shortage in the Northwest. Management of a shortage is critical, for even short-term adjustments could lead to permanent changes in service provision. This study demonstrates the importance of current information on the status of the national workforce and serves as a model for future studies. 相似文献
993.
994.
Ronald Martin Jaime Williams Thomas Hadjistavropoulos Heather D Hadjistavropoulos Michael MacLean 《Revue canadienne de recherche en sciences infirmières》2005,37(2):142-164
The literature suggests that pain in the elderly, especially among seniors with dementia, is under-assessed and under-treated.This qualitative study solicited the perspectives of seniors, front-line nursing staff, nursing-home administrators, and informal caregivers of seniors with dementia on the current status of pain assessment and management. The views of these participants complement the research findings reported in the literature. While some of their explanations and potential solutions concerning under-treatment of pain in seniors echo views that have been presented in the literature, the participants also pointed to factors and avenues that have been given less formal consideration (e.g., systemic barriers to effective assessment and treatment of pain).They also highlighted the need for pain-control strategies beyond medication. The implications of these findings are discussed. 相似文献
995.
J Hartung K D Kalache C Heyna K-S Heling M Kuhlig R Wauer R Bollmann R Chaoui 《Ultrasound in obstetrics & gynecology》2005,25(6):566-572
OBJECTIVE: To describe the course and outcome of fetuses with absent or reversed end-diastolic (ARED) flow in the umbilical artery (UA) and to examine the influence of prematurity according to gestational age at delivery. METHODS: Sixty pregnancies complicated by ARED flow in the UA were monitored by repeat Doppler measurements of arterial and venous vessels, non-stress tests (cardiotocogram (CTG)) and maternal investigations, and were delivered between 24 and 34 weeks. Fetal outcome was investigated and compared to a control group of appropriate-for-gestational age (AGA) preterm neonates, matched for gestational age. Mortality, birth weight, Apgar scores, postnatal cord arterial pH and need for ventilation were all recorded, as were cases of respiratory distress syndrome, bronchopulmonary dysplasia, persistent ductus arteriosus, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia, abnormal neurological findings and those requiring surgical intervention. Additionally, the group of fetuses with ARED flow was divided into three subgroups of different degrees of prematurity (delivery between 24 + 0 and 28 + 6 weeks, delivery between 29 + 0 and 31 + 6 weeks, and delivery after 32 weeks) and compared according to the above parameters. RESULTS: Pre- or postnatal death occurred in 16 cases. Comparing the 44 (61%) that were born alive with the AGA neonates, significant differences were found in birth weight (P < 0.001), arterial pH value (P < 0.001), bronchopulmonary dysplasia (P = 0.002) and intestinal complications (P < 0.01). Prematurity-related complications were: need for ventilation (P = 0.001), respiratory distress syndrome (P < 0.0001), periventricular leukomalacia (P = 0.002) and pathological neurological testing (P = 0.005). CONCLUSIONS: Neonates displaying ARED flow before birth are growth restricted, acidemic at delivery and are at high risk of developing bronchopulmonary dysplasia and intestinal complications. While perinatal mortality seems to be related to abnormal fetal Doppler velocimetry, age at delivery has a significant impact on short-term morbidity. After 32 weeks, morbidity is low and delivery should be considered. It could be speculated from our data that prolongation of pregnancy with Doppler velocimetry monitoring could help to reduce morbidity, although prolongation remains limited in most cases. 相似文献
996.
997.
998.
Joseph F Malouf Manfredi Ballo Heidi M Connolly David O Hodge Regina M Herges Charles J Mullany Fletcher A Miller 《Journal of the American Society of Echocardiography》2005,18(3):252-256
The purpose of this study was to provide, in a large number of patients, comprehensive Doppler echocardiographic assessment of normal St Jude Medical mitral valve prosthesis function using Doppler-derived hemodynamic variables, including the mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio and prosthesis performance index. The pressure half-time was less than 130 milliseconds in all patients, and all but one patient had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2. There was a significant (P < .001) negative correlation between the prosthesis performance index and prosthesis size. This negative correlation suggests that there is more efficient use of the in vitro geometric orifice area with smaller prostheses. 相似文献
999.
Sandeep Mahajan Suresh C Tiwari Vikram Kalra Dipankar M Bhowmik Sanjay K Agarwal Suresh C Dash Parveen Kumar 《Peritoneal dialysis international》2005,25(5):473-477
BACKGROUND: Staphylococcus aureus-associated peritonitis and catheter exit-site infections (ESIs) are important causes of hospitalization and catheter loss in patients undergoing chronic peritoneal dialysis. Intranasal and topical use of mupirocin has been found to be an effective strategy in decreasing S. aureus-related infectious complications in persons who are carriers of S. aureus; however, there is no consensus regarding the prophylactic use of mupirocin irrespective of carrier status. We aimed to determine the potential effectiveness of application of mupirocin cream at the catheter exit site in preventing ESI and peritonitis irrespective of carrier status in a tropical country such as India. METHODS: This prospective historically controlled study was done in a total of 40 patients. From August 2003, all patients, incident and prevalent, were instructed to apply 2% mupirocin cream daily to the exit site instead of the older practice of povidone-iodine and gauze dressing. Patients were not screened to determine whether they were S. aureus carriers. The infection-related data for 1 year, until July 2004, were compared with the historical control, which was infection-related data for the year preceding the year of mupirocin application. RESULTS: Mean age of the study population was 62 years, with 61.8% being male and 64.3% being diabetic. Local application of mupirocin led to a significant reduction in the incidence density per patient-month of both ESI and peritonitis compared to controls (0.15 vs 0.37 and 0.37 vs 0.67, p = 0.01 for both). This amounted to a relative reduction of 60.5% and 55% respectively. ESI and peritonitis due to S. aureus were also significantly lower in the study group compared to controls (incidence density per patient-month 0.05 vs 0.13 and zero vs 0.17 respectively, p < 0.01 for both). There occurred no catheter removal due to infection-related complications during the study period compared to two during the control period. None of the patients reported a mupirocin-related adverse effect. CONCLUSIONS: Daily application of mupirocin at the exit site is a well-tolerated and effective strategy in reducing the incidence of ESI and peritonitis in a tropical country such as India. It can thus significantly reduce morbidity, catheter loss, and transfer to hemodialysis in peritoneal dialysis patients. 相似文献
1000.