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   6503篇
  免费   593篇
  国内免费   27篇
耳鼻咽喉   38篇
儿科学   253篇
妇产科学   269篇
基础医学   820篇
口腔科学   171篇
临床医学   803篇
内科学   1254篇
皮肤病学   92篇
神经病学   706篇
特种医学   438篇
外国民族医学   1篇
外科学   611篇
综合类   148篇
一般理论   5篇
预防医学   534篇
眼科学   169篇
药学   276篇
中国医学   40篇
肿瘤学   495篇
  2023年   44篇
  2022年   49篇
  2021年   116篇
  2020年   64篇
  2019年   121篇
  2018年   140篇
  2017年   129篇
  2016年   107篇
  2015年   121篇
  2014年   163篇
  2013年   243篇
  2012年   305篇
  2011年   342篇
  2010年   204篇
  2009年   191篇
  2008年   343篇
  2007年   291篇
  2006年   260篇
  2005年   298篇
  2004年   258篇
  2003年   261篇
  2002年   235篇
  2001年   206篇
  2000年   186篇
  1999年   159篇
  1998年   142篇
  1997年   122篇
  1996年   113篇
  1995年   101篇
  1994年   96篇
  1993年   92篇
  1992年   143篇
  1991年   108篇
  1990年   112篇
  1989年   128篇
  1988年   156篇
  1987年   111篇
  1986年   111篇
  1985年   106篇
  1984年   76篇
  1983年   59篇
  1982年   46篇
  1981年   46篇
  1980年   45篇
  1979年   44篇
  1978年   33篇
  1977年   39篇
  1976年   26篇
  1975年   32篇
  1973年   25篇
排序方式: 共有7123条查询结果,搜索用时 0 毫秒
21.
The right hepatic artery was catheterized for chemoembolization in a patient with liver-dominant metastatic breast carcinoma and occlusion of the celiac artery by tumor compression. This was accomplished by use of a new coaxial infusion catheter-steerable guidewire system passed through the superior mesenteric artery and posterior pancreatic arcade.  相似文献   
22.
A new method to investigate the anatomy of the lower urinary tract in women is described. Direct ultrasound images of the bladder neck and proximal urethra were obtained using a vaginal endoprobe; the series comprised 100 women with a range of urinary symptoms. The technique was well tolerated by patients and there was no morbidity. Transvaginal endosonography is suitable for the assessment of many aspects of urinary incontinence.  相似文献   
23.
The purpose of this study was to examine motor learning and retention given extensive practice in two fundamentally different movement sequences. One sequence was a memory-driven task (performing a series of whole body positions from memory) and the other a context-driven task (buttoning). Practice took place over 3 weeks, with performance measured weekly; retention was measured weekly for 3 weeks after practice. There were 7 people with Parkinson's disease (PD) and 7 age-matched neurologically healthy people who participated in this study. Both groups improved performance on both tasks with practice, with the majority of the change for the PD group occurring between 1 and 2 weeks of practice. Although those with PD did not necessarily perform as well as age-matched controls, they learned both sequences in a manner similar to age-matched controls, and exhibited retention across the 3-week retention interval. If people with PD are given sufficient practice they can learn and retain both memory-based and context-driven movement sequences as well as age-matched controls. The results provide support for maintaining physical activity and for intervention through movement therapy.  相似文献   
24.
A prospective investigation of pulmonary embolism in women and men.   总被引:4,自引:0,他引:4  
OBJECTIVE. The aim of this study was to compare, in women and men suspected of pulmonary embolism, the frequency, risk factors, diagnosis, and presentation of pulmonary embolism as well as the accuracy of the ventilation/perfusion scan (V/Q scan) as a diagnostic tool. DESIGN. Data were collected during a prospective study (the Prospective Investigation of Pulmonary Embolism Diagnosis) to establish the accuracy of the V/Q scan compared with pulmonary angiograms. SETTING. Six tertiary medical centers in Massachusetts, Michigan, Connecticut, Pennsylvania, and North Carolina. PARTICIPANTS. Patients suspected of pulmonary embolism for whom a request was made for a V/Q scan or pulmonary angiogram (496 women and 406 men). RESULTS. Women 50 years old and under had a decreased frequency of pulmonary embolism compared with men of that age (16% vs 32%), but there was no difference in patients over 50 years old (Breslow-Day test, P less than .01). Risk factors for pulmonary embolism, the usefulness of the V/Q scan, and 1-year mortality were not different for women and men. Estrogen use in women was not associated with an increased frequency of pulmonary embolism, except in women using oral contraceptives who had undergone surgery within 3 months; four of five (80%) had emboli compared with four of 28 (14%) age-matched surgical patients not using estrogens (P less than .01). CONCLUSION. Women 50 years old and under (even young women using oral contraceptives) who were suspected of having pulmonary emboli and were enrolled in the Prospective Investigation of Pulmonary Embolism Diagnosis study had a smaller frequency of pulmonary embolism than men of that age, The risk factors for pulmonary embolism were the same for women and men, except that women using oral contraceptives had an increased risk of pulmonary embolism following surgery. Although the V/Q scan was a useful tool in the preliminary evaluation for pulmonary embolism in these women, a pulmonary angiogram was often needed for accurate diagnosis.  相似文献   
25.
We reviewed the current literature on the role of antibiotic therapy in cystic fibrosis, concentrating on studies directing therapy at Pseudomonas aeruginosa. To highlight controversial areas, we examined studies comparing monotherapy with combination therapy, home intravenous treatment versus hospital treatment, intravenous versus oral therapy, and the role of aerosolized antibiotics. We found that all systemic therapies with antipseudomonal activity were of comparable efficacy. Data on the efficacy of aerosolized treatment were equivocal. There is a substantial body of anecdotal literature addressing the issue of antibiotic resistance complicating treatment of cystic fibrosis. This will be briefly reviewed and the responsible mechanisms will be outlined. There is a secular trend for selection of more resistant pathogens in the lungs of CF patients. In the individual patient, however, emergence of antibiotic resistance may occur without deleterious clinical effects.  相似文献   
26.
We studied the association between deprivation and survival from breast cancer in 29,676 women aged 30 and over who were diagnosed during the period 1980-89 in the area covered by the South Thames Regional Health Authority. The measure of deprivation was the Carstairs Index of the census enumeration district of each woman''s residence at diagnosis. We studied the impact of stage at diagnosis, morphology and type of treatment on this association, with the relative survival rate and the hazard ratio as measures of outcome. There was a clear gradient in survival, with better survival for women from more affluent areas. At all ages, women in the most deprived category had a 35% greater hazard of death than women from the most affluent areas after adjustment for stage at diagnosis, morphological type and type of treatment. In younger women (30-64 years), the survival gradient by deprivation category cannot be explained by these prognostic factors. In older women (65-99 years), part of the unadjusted gradient in survival can be explained by differences in the stage of disease: older women in the most deprived category were more often diagnosed with advanced disease. Other factors, so far unidentified, are responsible for the gradient in breast cancer survival by deprivation category. The potential effect on breast cancer mortality of eliminating the gradient in survival by deprivation category is substantial (7.4%). In women aged 30-64 years, 10% of all deaths within 5 years might be avoidable, while in older women this figure is 5.8%.  相似文献   
27.
Bone resorption by macrophage polykaryons of a pilar tumor of scalp.   总被引:1,自引:0,他引:1  
N A Athanasou  J M Quinn 《Cancer》1992,70(2):469-475
The nature of keratin-associated giant cells of a pilar tumor of scalp (PTS) was assessed for several osteoclast-like characteristics, including antigenic phenotype, ultrastructure, calcitonin response, and bone resorbing ability. The giant cells, unlike osteoclasts, did not respond morphologically to calcitonin, had the antigenic phenotype of cells of the monocyte/macrophage lineage, and showed ultrastructural features of macrophage polykaryons. However, like osteoclasts, the giant cells were capable of bone resorption, including resorption pit formation. This indicates that the giant cells in PTS are of histiocytic and not osteoclastic differentiation. Bone resorption by tumor-associated macrophage polykaryons shows that this is not a unique defining characteristic of osteoclasts. It also suggests that such histiocytic cells may contribute to the osteolysis associated with skeletal metastases of squamous and other carcinomas.  相似文献   
28.
Between 1/1/76 and 12/31/86, 448 patients underwent transplantation (360 first transplants). Of these, 286 (230 first) were referred by 5 dialysis centers, each referring more than 40 recipients. The remainder were referred by a large number of centers. Using our 5 largest referral centers, we studied the effect of dialysis center on graft and patient survival. There was no difference between dialysis centers in patient survival. Actuarial graft survival differed significantly for all cadaver transplants and for first cadaver transplants (P less than 105). Significant differences persisted when groups were subdivided by type of immunosuppression (azathioprine vs cyclosporine). Demographic (age, race, cause of renal disease) and immunologic (transfusions, PRA, matching) differences between groups did not explain the difference in graft survival. We conclude that referring dialysis center is a previously unrecognized factor affecting transplant outcome. Further studies with larger numbers will be required to determine the underlying reasons for ths phenomenon.  相似文献   
29.
We report a metallic foreign body that entered through the anterior table of the frontal sinus, and rolled down to lodge in the nasofrontal duct. An electromagnet was used to remove the foreign body through a trephination.  相似文献   
30.
This study evaluated a multiple‐family group‐intervention program (MFGI) for first‐time juvenile offenders. The recidivism rate for subjects who completed the MFGI (the Family Solutions Program) was compared to recidivism rates of two other groups of first‐time juvenile offenders. Using logistic regression analysis predicting who will recidivate, juvenile first offenders who were placed on probation (N = 95) were 9.3 times more likely to re‐offend compared to the Family Solutions Program (FSP) graduates (N = 267). Families referred to FSP but who dropped out (most never attended the 10 session program) (N = 93) also were 4.4 times more likely to re‐offend compared to FSP graduates. An intent‐to‐treat model comparing the combined group of FSP graduates and dropouts with the probation group indicated that a youth in the probation group was 8.1 times more likely to re‐offend than a youth referred to the FSP. Results indicating better outcomes on recidivism for FSP graduates were significant for both male and female youths. Implications for policy and practitioners are discussed. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 177–200, 2004.  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