全文获取类型
收费全文 | 27964篇 |
免费 | 1736篇 |
国内免费 | 71篇 |
专业分类
耳鼻咽喉 | 246篇 |
儿科学 | 616篇 |
妇产科学 | 489篇 |
基础医学 | 3921篇 |
口腔科学 | 643篇 |
临床医学 | 2578篇 |
内科学 | 5371篇 |
皮肤病学 | 475篇 |
神经病学 | 3106篇 |
特种医学 | 1130篇 |
外国民族医学 | 55篇 |
外科学 | 3887篇 |
综合类 | 363篇 |
一般理论 | 10篇 |
预防医学 | 2181篇 |
眼科学 | 796篇 |
药学 | 1932篇 |
中国医学 | 32篇 |
肿瘤学 | 1940篇 |
出版年
2022年 | 194篇 |
2021年 | 385篇 |
2020年 | 232篇 |
2019年 | 383篇 |
2018年 | 433篇 |
2017年 | 359篇 |
2016年 | 400篇 |
2015年 | 540篇 |
2014年 | 721篇 |
2013年 | 1071篇 |
2012年 | 1583篇 |
2011年 | 1643篇 |
2010年 | 903篇 |
2009年 | 845篇 |
2008年 | 1551篇 |
2007年 | 1659篇 |
2006年 | 1590篇 |
2005年 | 1613篇 |
2004年 | 1537篇 |
2003年 | 1442篇 |
2002年 | 1403篇 |
2001年 | 402篇 |
2000年 | 354篇 |
1999年 | 367篇 |
1998年 | 313篇 |
1997年 | 304篇 |
1996年 | 260篇 |
1995年 | 246篇 |
1994年 | 211篇 |
1993年 | 211篇 |
1992年 | 226篇 |
1991年 | 211篇 |
1990年 | 188篇 |
1989年 | 197篇 |
1988年 | 191篇 |
1987年 | 200篇 |
1986年 | 173篇 |
1985年 | 176篇 |
1984年 | 223篇 |
1983年 | 192篇 |
1982年 | 229篇 |
1981年 | 211篇 |
1980年 | 192篇 |
1979年 | 166篇 |
1978年 | 155篇 |
1977年 | 106篇 |
1976年 | 143篇 |
1975年 | 128篇 |
1974年 | 154篇 |
1973年 | 114篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Diagnostic performance of liquid crystal and cathode-ray-tube monitors in brain computed tomography 总被引:7,自引:0,他引:7
Pärtan G Mayrhofer R Urban M Wassipaul M Pichler L Hruby W 《European radiology》2003,13(10):2397-2401
The aim of this study was to evaluate feasibility of reporting brain CT examinations on liquid crystal display (LCD) flat-screen
monitors vs state-of-the-art cathode-ray-tube (CRT) monitors. Ninety-five brain CT examinations of 95 patients were displayed
on Picture archiving and communications system (PACS) workstations equipped either with a dedicated medical imaging LCD colour
monitor or on a high-resolution CRT which is used for routine reporting of CT, MRI and digital radiography images in our institution.
Fifty cases were negative and 45 cases were positive for early brain infarction (EBI), the latter being defined by a combination
of one or more signs: dense artery; hypodensity of brain parenchyma; and local brain swelling verified by control scans. Ten
radiologists had to rate presence or absence of EBI on a five-point scale. Ratings were evaluated by CORROC2 ROC software
and areas under the ROC curve (Az) were computed. Significance of differences between the two viewing conditions were evaluated with Wilcoxon test. Mean Az of the ten observers was 0.7901 with LCD vs 0.7695 with CRT which did not show statistical significance (p=0.2030). In the setting investigated, reporting of CT studies from high-performance LCD monitors seems feasible without significant
detriment to diagnostic performance. 相似文献
992.
Lumbar spine radiography: digital flat-panel detector versus screen-film and storage-phosphor systems in monkeys as a pediatric model 总被引:6,自引:0,他引:6
Ludwig K Ahlers K Wormanns D Freund M Bernhardt TM Diederich S Heindel W 《Radiology》2003,229(1):140-144
PURPOSE: To assess image quality and exposure dose requirements of a flat-panel detector system versus screen-film and storage-phosphor systems for radiographic depiction of the lumbar spine in Cynomolgus monkeys as a pediatric model. MATERIALS AND METHODS: Twenty Cynomolgus monkeys underwent anteroposterior radiography of the lumbar spine. The size and weight of these monkeys are comparable to those of infants 3-4 months of age. Images were acquired with speed class 400 screen-film, flat-panel, and storage-phosphor systems with identical exposure dose. All other conditions were matched exactly. Additional images were acquired with the flat-panel and storage-phosphor systems at exposure doses equivalent to speed classes 800 and 1600. All images were obtained at 66 kVp without antiscatter grid. Images were assessed independently by three radiologists for visibility of 60 anatomic structures by using a five-point confidence scale. Scores were calculated for the seven combinations of imaging mode and exposure dose and were compared by using the Friedman test. RESULTS: Scores were 1.70 (speed class 400), 1.97 (speed class 800), and 2.27 (speed class 1600) for the flat-panel system; 2.50 (speed class 400) for the screen-film system; and 2.58 (speed class 400), 2.77 (speed class 800), and 3.13 (speed class 1600) for the storage-phosphor system. Scores for the flat-panel system at speed classes 400 and 800 were significantly lower (indicating better visibility) than those of the screen-film and storage-phosphor systems (P <.05). CONCLUSION: The flat-panel system is superior to screen-film and storage-phosphor systems in lumbar spine radiography in monkeys. With the flat-panel system, exposure dose can be reduced by 75% without loss in image quality. 相似文献
993.
Marcel Betsch Michael Wild Birgit Gro?e Walter Rapp Thomas Horstmann 《European spine journal》2012,21(4):691-697
Introduction
Leg length inequalities (LLI) are a common finding. Rasterstereography offers a non-invasive, contact-free and reliable method to detect the effects of LLIs on spinal posture and pelvic position. 相似文献994.
Irwin DE Milsom I Hunskaar S Reilly K Kopp Z Herschorn S Coyne K Kelleher C Hampel C Artibani W Abrams P 《European urology》2006,50(6):1306-14; discussion 1314-5
OBJECTIVE: Estimate the prevalence of urinary incontinence (UI), overactive bladder (OAB), and other lower urinary tract symptoms (LUTS) among men and women in five countries using the 2002 International Continence Society (ICS) definitions. METHODS: This population-based, cross-sectional survey was conducted between April and December 2005 in Canada, Germany, Italy, Sweden, and the United Kingdom using computer-assisted telephone interviews. A random sample of men and women aged >/= 18 yr residing in the five countries and who were representative of the general populations in these countries was selected. Using 2002 ICS definitions, the prevalence estimates of storage, voiding, and postmicturition LUTS were calculated. Data were stratified by country, age cohort, and gender. RESULTS: A total of 19,165 individuals agreed to participate; 64.3% reported at least one LUTS. Nocturia was the most prevalent LUTS (men, 48.6%; women, 54.5%). The prevalence of storage LUTS (men, 51.3%; women, 59.2%) was greater than that for voiding (men, 25.7%; women, 19.5%) and postmicturition (men, 16.9%; women, 14.2%) symptoms combined. The overall prevalence of OAB was 11.8%; rates were similar in men and women and increased with age. OAB was more prevalent than all types of UI combined (9.4%). CONCLUSIONS: The EPIC study is the largest population-based survey to assess prevalence rates of OAB, UI, and other LUTS in five countries. To date, this is the first study to evaluate these symptoms simultaneously using the 2002 ICS definitions. The results indicate that these symptoms are highly prevalent in the countries surveyed. 相似文献
995.
Severe injuries at foot and ankle level with loss of soft tissues and bone are often treated by means of amputation. The transfer of composite free flaps from various donor sites may provide anatomical reconstruction of the foot and ankle and function. Ten patients who sustained severe combined tissue injuries of the foot requiring reconstruction with composite free flaps were studied with a mean follow-up of 3.4 years. A thorough clinical examination was performed, and gait analysis was carried out with kinetic and kinematic parameters. Bone integration and healing was observed with satisfactory foot morphology. All the patients returned to normal activities, although biomechanical gait analysis showed some functional disorders mainly in joint angular kinematics. Our results showed that microvascular flaps afford successful combined tissue reconstruction of the foot. 相似文献
996.
Atkins BZ Onaitis MW Hutcheson KA Kaye K Petersen RP Wolfe WG 《American journal of surgery》2011,202(5):565-567
Background
Post-sternotomy mediastinitis reduces survival after cardiac surgery, potentially further affected by details of mediastinal vascularized flap reconstruction. The aim of this study was to evaluate survival after different methods for sternal reconstruction in mediastinitis.Methods
Two hundred twenty-two adult cardiac surgery patients with post-sternotomy mediastinitis were reviewed. After controlling infection, often augmented by negative pressure therapy, muscle flap, omental flap, or secondary closure was performed. Outcomes were reviewed and survival analysis was performed.Results
Baseline characteristics were similar. In-hospital mortality (15.7%) did not differ between groups. Secondary closure was correlated with negative pressure therapy and reduced length hospital of stay. Recurrent wound complications were more common with muscle flap repair. Survival was unaffected by sternal repair technique. By multivariate analysis, heart failure, sepsis, age, and vascular disease independently predicted mortality, while negative pressure therapy was associated with survival.Conclusions
Choice of sternal repair was unrelated to survival, but mediastinal treatment with negative pressure therapy promotes favorable early and late outcomes. 相似文献997.
998.
Katrin D. Bartl-Pokorny Peter B. Marschik Jeff Sigafoos Helen Tager-Flusberg Walter E. Kaufmann Tobias Grossmann Christa Einspieler 《Research in developmental disabilities》2013,34(10):3133-3138
Rett syndrome (RTT) is a severe neurological disorder characterized by a developmental regression in motor and speech-language domains. There is, however, limited research on socio-communicative development of affected children before the onset of regression. We analyzed audio–video recordings made by parents of six 9- to 12-month old girls later diagnosed with typical RTT, applying the Inventory of Potential Communicative Acts (IPCA) to identify early communicative forms and functions. Each girl used at least one communicative form (e.g., body movement, eye gaze, or vocalizations) to gain attention and answer, but none were observed to make choices or request information. Varying numbers of children were observed to perform other communicative functions according to the IPCA including social convention, rejecting or requesting an object. Non-verbal forms (e.g., reaching, moving closer, eye contact, smiling) were more common than non-linguistic verbal forms (e.g., unspecified vocalizations, pleasure vocalizations, crying). (Pre-)linguistic verbal forms (e.g., canonical or variegated babbling, proto-words) were not used for communicative purposes. These data suggest that atypical developmental patterns in the socio-communicative domain are evident prior to regression in young individuals later diagnosed with RTT. 相似文献
999.
Summary Plasma and intracellular levels of lactate dehydrogenase (LDH), phosphohexose isomerase (PHI) and lysozyme activities were investigated in 20 patients with acute myelocytic leukemia (AML), 18 patients with acute lymphatic leukemia (ALL) and 10 patients with chronic myelocytic leukemia in blast transformation (CML/BT). Though the plasma levels of LDH and PHI in all patients with acute leukemia were elevated as compared to control persons there was no distinctive pattern which could be of use in the classification of acute leukemia. On the other hand the intracellular levels of these enzymes could be of value in classifying acute leukemia. The leukemic lymphoblasts were characterized by low levels of PHI and lysozyme as compared to leukemic myeloblasts or to normal lymphocytes (p<0.01). The LDH/PHI ratio is also significantly higher in leukemic lymphoblasts than in leukemic myeloblasts or in normal lymphocytes (p always <0.01). These characteristics might also be made use of in identifying the blasts of CML/BT als lymphoid or myeloid in corresponding cases. 相似文献
1000.
Robert M. Walter Hedley C. Freake Junji Iwasaki John Lynn Iain MacIntyre 《Metabolism: clinical and experimental》1984,33(3):240-243
We examined ten cellular or tissue sources of lymphocytes for specific binding of 1,25(OH)2D3, the hormonally active form of vitamin D3. A specific-binding protein was found in three of these sources. Scatchard analysis of cytosol from a follicular lymphoma cell line revealed binding sites with a Kd of 7.0 × 10?11 and a receptor concentration of 6.6 fmol/mg protein. Sucrose density centrifugation of 3H-1,25(OH)2D3 labeled cytosol showed a 3.75 peak which was absent in cytosols incubated with excess nonradioactive 1,25(OH)2D3. The relative amounts of vitamin D3 metabolites required to displace 50% of the specifically bound 3H-1,25(OH)2D3 were 1,25(OH)2D3: 1,24,25(OH)3D3: 25(OH)D3: 24,25(OH)2D3 = 1: 180: 1000: 2700. Excess vitamin D3, cortisol, and estradiol failed to displace 3H-1,25(OH)2D3. Scatchard analysis of spleen cytosol from a patient with prolymphocytic transformation of chronic lymphocytic leukemia demonstrated a binding protein with a Kd of 1.2 × 10?10 and a receptor concentration of 0.2 fmol/mg protein. DNA cellulose binding confirmed the presence of the specific-binding protein in this cytosol. Specific binding of 3H-1,25(OH)2D3 was also quantitated in a cell line from a patient with Burkitt's lymphoma with a Kd of 0.3 × 10?10 and a receptor concentration of 29.6 fmol/mg protein. No specific binding of 3H-1,25(OH)2D3 was observed in lymphocytes from seven other malignant and nonmalignant sources. These results are the first to demonstrate a specific-binding protein for 1,25(OH2D3 in lymphocytes from tissue and from these specific cell lines. The presence of this protein in some lymphocytes but not others may reflect the state of activation of the lymphocytes. 相似文献