全文获取类型
收费全文 | 16553篇 |
免费 | 5428篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 518篇 |
儿科学 | 512篇 |
妇产科学 | 669篇 |
基础医学 | 119篇 |
口腔科学 | 1091篇 |
临床医学 | 3497篇 |
内科学 | 6135篇 |
皮肤病学 | 340篇 |
神经病学 | 710篇 |
特种医学 | 248篇 |
外科学 | 1783篇 |
综合类 | 30篇 |
现状与发展 | 2篇 |
预防医学 | 3391篇 |
眼科学 | 235篇 |
药学 | 196篇 |
肿瘤学 | 2538篇 |
出版年
2024年 | 160篇 |
2023年 | 1048篇 |
2022年 | 361篇 |
2021年 | 653篇 |
2020年 | 1193篇 |
2019年 | 402篇 |
2018年 | 1097篇 |
2017年 | 1174篇 |
2016年 | 1412篇 |
2015年 | 1366篇 |
2014年 | 1934篇 |
2013年 | 2118篇 |
2012年 | 641篇 |
2011年 | 553篇 |
2010年 | 1086篇 |
2009年 | 1500篇 |
2008年 | 565篇 |
2007年 | 354篇 |
2006年 | 656篇 |
2005年 | 278篇 |
2004年 | 221篇 |
2003年 | 151篇 |
2002年 | 131篇 |
2001年 | 264篇 |
2000年 | 229篇 |
1999年 | 241篇 |
1998年 | 321篇 |
1997年 | 247篇 |
1996年 | 238篇 |
1995年 | 197篇 |
1994年 | 151篇 |
1993年 | 112篇 |
1992年 | 113篇 |
1991年 | 93篇 |
1990年 | 107篇 |
1989年 | 83篇 |
1988年 | 69篇 |
1987年 | 53篇 |
1986年 | 59篇 |
1985年 | 47篇 |
1984年 | 43篇 |
1983年 | 41篇 |
1982年 | 15篇 |
1980年 | 20篇 |
1977年 | 29篇 |
1975年 | 16篇 |
1974年 | 12篇 |
1972年 | 14篇 |
1959年 | 16篇 |
1958年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Background: Vitamin B12 deficiency after gastric surgery for obesity is due to a failure of separation of vitamin B12 from protein foodstuffs and to a failure of absorption of crystalline vitamin B12 in the presence of intrinsic factor. The purpose of this study was to determine which of four oral doses of crystalline vitamin
B12 was most effective in treating vitamin B12 deficiency in 102 patients. Methods and Results: At time of entry into the study, the patients had a serum vitamin B12 < 100 pmol L −1, were 29.9 ± 21.7 months post-op, were 37 ± 8 years old and had a body mass index of 30 ± 6 kg m−2. Eight (8%) had had a vertical banded gastroplasty and 94 (92%) a gastric bypass. For the first 3 months all patients received
350 μg per day of crystalline vitamin B12 and all increased their serum vitamin B12 levels to over 100 pmol L−1. The patients were then assigned to receive for a further 3 month period one of four oral doses of crystalline vitamin B12-100 μg, 250 μg, 350 μg and 600 μg. Serum vitamin B12 levels were greater than 150 pmol L−1 after 6 months in 83.3% of patients who received 100 μg; 92.3% of patients who received 250 μg; 94.7% after 350 μg and 95.2%
after 600 μg (p%0.525). Conclusion: At least 350 μg per day is the appropriate oral dose of crystalline vitamin B12 after gastric surgery for obesity to correct low serum vitamin B12 levels in 95% of patients. 相似文献
102.
John P. Sciacca PhD MPH CHES David A. Dube MPH RD Brenda L. Phipps BS CLE Michael I. Ratliff PhD 《Journal of community health》1995,20(6):473-490
This study was undertaken to determine the effects of a partner-support, incentive-baed educational program on breast feeding knowledge, attitudes and support and to examine the relationship between feeding intentions and feeding behavior among low-income women. Women who expressed a willingness to participate in the intervention were randomly assigned to intervention and usual breast feeding (control) groups. Sixty-eight primipara women, with expected due dates between May and December, 1992, volunteered to participate in the study. Of these, 34 were randomly assigned to each of the two groups. Approximately 81 percent of the women completed the study, leaving n=29 in the control group and n-26 in the intervention group. The intervention consisted of special incentives (prizes) for women and their partners to participate in several breast feeding education and promotion activities. Intervention group women and their partners experienced positive changes in breast feeding knowledge and attitudes. Furthermore, the intervention seemed to have influenced more women in the treatment group to breast feed despite their prenatal feeding intentions. In addition, the partners of intervention group women were perceived to be more supportive of, breast feeding than control group partners. These findings suggest that incentives, such as donated prizes, can be used to attract lower socioeconomic group women and their partners to breast feeding promotion interventions. Participation in such interventions can produce positive changes in breast feeding knowledge, attitudes, and support, and can have a dramatic effect in promoting breast feeding.This study was supported through contract no. 59-3198-1-050 from the Food and Nutrition Service, U.S. Department of Agriculture. 相似文献
103.
Drs. Christopher Williams PhD Ms. Jennifer A. Epstein PhD Gilbert J. Botvin PhD Michelle Ifill-Williams MPH 《Journal of urban health》1999,76(1):85-101
Youths residing in public housing developments appear to be at markedly heightened risk for drug use because of their constant
exposure to violence, poverty, and drug-related activity. The purpose of this study was to develop and test a model of marijuana
etiology with adolescents (N=624) residing in public housing. African-American and Hispanic seventh graders completed questionnaires
about their marijuana use, social influences to smoke maijuana, and sociodemographic and psychosocial characteristics. Results
indicated that social influences, such as friends' marijuana use and perceived ease of availability of marijuana, significantly
predicted both occasional and future use of marijuana. Individual characteristics such as antimarijuana attitudes and drug
refsul skills also predicted marijuana use. The findings imply that effective prevention approaches that target urban youths
residing in public housing developments should provide them with an awareness of social influences to use marijuana, correct
misperceptions about the prevalence of marijuana smoking, and train adolescents in relevant psychosocial skills. 相似文献
104.
SOO-KYUNG LEE PhD RD JEFFEREY SOBAL PhD MPH EDWARD A FRONGILLO Jr PhD 《Journal of the American Dietetic Association》1999,99(9):1084-1089
OBJECTIVE: Examine variation in dietary practices and nutritional intakes of Korean Americans at different acculturation levels. DESIGN: Cross-sectional mail survey. SUBJECTS/SETTING: US national sample of 348 Korean Americans (46% of the Korean American sample to whom questionnaires were delivered). STATISTICAL ANALYSIS PERFORMED: Analysis of variance, Pearson correlation, Spearman rank correlation, chi 2 test, and multiple regression analysis. RESULTS: Korean Americans who were more acculturated consumed more American food and less Korean food. American foods such as oranges, low-fat milk, bagels, tomatoes, and bread were consumed regularly by Korean Americans; Korean foods such as rice, kimchi, garlic, green onions, and Korean soup were also consumed regularly. American foods were adopted the most at breakfast and the least at dinner. Bicultural people regularly incorporated more different types of foods into their diet. Despite significant differences in dietary practices, dietary quality did not vary by acculturation status. APPLICATION/CONCLUSIONS: Acculturation was influential in the dietary patterns of Korean Americans. Specific information about Korean diet related to acculturation status can be used by dietitians who work with Korean Americans. Dietitians can benefit from gathering and applying specific information about Korean diets and diets of other ethnic groups; they also need to recognize the changing nature of dietary patterns as acculturation occurs. 相似文献
105.
Background: The complications of the gastric pouch in gastric bypass surgery are well known. Since the first report of this
surgery 30 years ago, new technical aspects that make it safer and more effective have been implemented. Methods: As a modification
of gastric bypass, the authors have performed 305 vertical banded gastroplasty-gastric bypass procedures. Two groups of patients
underwent the procedure: Group I (n = 206) without a limb of jejunum interposed between the gastric pouch and the excluded
stomach, and Group II (n = 99) with a limb of jejunum interposed between the pouch and the stomach. The results regarding
excess weight loss and complications of the gastric pouch during the first year after surgery were compared. Results: Age,
sex, initial weight, body mass index, and percentage of ideal weight were similar in both groups. Excess weight loss was also
similar. The complications in Group I were 1 leak, 3 left subphrenic abscesses, 2 erosive gastritis with bleeding, 1 stenosis
of the gastrojejunostomy, 1 perforated ulcer, and 4 marginal ulcers with bleeding. Two patients in Group II developed bleeding
from the staple-line. Conclusions: These preliminary data suggest that complications of the gastric pouch can be reduced by
interposing a limb of jejunum between the pouch and the excluded stomach. This is an early experience; long-term results are
pending. 相似文献
106.
Iris P. Masucci PharmD Karim A. Calis PharmD MPH David L. Bartlett MD H. Richard Alexander MD McDonald K. Horne III MD 《Annals of surgical oncology》1999,6(5):476-480
Background: Three cases of heparin-induced thrombocytopenia (HIT) were observed in patients undergoing isolated limb perfusion (ILP) with melphalan. This occurrence prompted the discontinuation of prophylactic postoperative heparin in ILP patients and its avoidance in patients undergoing isolated hepatic perfusion (IHP). The need to reassess these decisions led to a review of thrombocytopenia in both patient populations.Methods: Records of all patients treated with ILP or IHP at our institution from July 1992 through November 1996, were reviewed. Nine IHP patients were tested prospectively for heparinrelated antibodies using serum samples obtained perioperatively and during the second postoperative week.Results: Thrombocytopenia (<100,000 platelets/L) developed postoperatively in 30% of 131 ILP patients and in 77% of 56 IHP patients. No cases of HIT were identified other than the three who had been previously diagnosed. The prevalence of HIT in heparinized ILP patients was 2.8% (3/108). All nine IHP patients developed heparin-related antibodies postoperatively.Conclusions: Because the prevalence of HIT following ILP is in the range observed in other clinical settings, postoperative heparin prophylaxis is an option. However, it probably should be limited to the first week, and daily platelet counts should be reviewed for a pattern of thrombocytopenia consistent with HIT. The prevalence of heparin-related antibodies after IHP is so high that prophylactic heparin should be avoided in this setting. 相似文献
107.
JEFFREY E. TERRELL MD KINJAL NANAVATI MPH RAMON M. ESCLAMADO MD CAROL R. BRADFORD MD GREGORY T. WOLF MD 《Otolaryngology--head and neck surgery》1999,120(6):852-859
A multidimensional Head and Neck Quality of Life (HNQOL) instrument and a general health status measure were administered to 397 patients with head and neck cancer. Scores for the 4 domains of the HNQOL (communication, eating, pain, and emotional well-being) were calculated. Patient demographics, comorbidities, clinical characteristics, treatment data, disability status, and a global "overall bother" score were assessed. When compared with the US population aged 55 to 64 years, the group had significantly worse scores in the 8 health domains of the SF-36. Patients' overall bother scores from the head and neck cancer treatment correlated best with the HNQOL emotion domain (r = 0.71) and the HNQOL pain domain (r = 0.63), and least with the patients' perception of their response to treatment (r = 0.39). Pain, eating, emotion, physical component summary score, age, and an interaction term between eating and emotion were significant predictors for overall bother. Of the 217 patients who were working before the diagnosis of cancer, 74 (34. 1%) reported that they had become disabled. Patients who had more than 1 type of treatment were 5.9 times more likely to report themselves as disabled (odds ratio [OR] = 5.94, P < 0.01), even after adjusting for age, emotion score, and physical component summary score, which were other factors that predicted disability. 相似文献
108.
PIERRE-MARC BOULOUX SALVATORE CORSELLO MICHAEL BESSER ASHLEY GROSSMAN 《British journal of clinical pharmacology》1996,42(2):225-232
- Intravenous bolus doses of thyrotrophin releasing hormone (TRH, 50–1000 μg) caused statistically significant, non-dose dependent and transient rises in blood pressure, heart rate and plasma catecholamines in healthy young males.
- Mean peak incremental rises in systolic blood pressure (mean ± s.e. mean) following 50, 200 and 500 μg TRH were 14.3 ± 2.9 mmHg, 15.7 ± 3.2 mmHg and 17.1 ± 3.9 mmHg respectively (all P < 0.05 vs placebo). Mean incremental rises in heart rate for the three doses of TRH were 8.2 ± 2.2 beats min−1, 7.1 ± 1.8 beats min−1, and 1O.7 ± 2.9 beats min−1 respectively (all P < 0.05 vs placebo).
- Following the 50 μg and 1000 μg doses of TRH, plasma noradrenaline and adrenaline rose significantly (P < 0.05) between 4 and 8 min. Mean ± s.e. mean incremental plasma noradrenaline rise following 50, 200 and 1000 μg TRH were 0.4 ± O.13 nmol 1−1, 0.37 ± 0.21 nmol 1−1 and 0.41 ± 0.18 nmol 1−1 respectively. Mean ± s.e. mean incremental rise in adrenaline for the 50, 200 and 1000 μg dose were 0.13 ± 0.04 nmol 1−1, 0.08 ± 0.03 nmol 1−1, and 0.11 ± 0.05 nmol l−1 respectively.
- Following administration of the ganglion blocking drug pentolinium (5 mg) the incremental systolic blood pressure and heart rate rises following 500 μg TRH alone 16.6 ± 2.8 mmHg and 1O.4 ± 3.1 beats min−1 respectively.
- The rises in plasma noradrenaline and adrenaline following TRH were attenuated by prior ganglion blockade.
- α-adrenoceptor blockade with thymoxamine (0.3 mg kg−1 bolus + 0.3 mg kg−1 h−1 infusion), singly and combined with intravenous propranolol (10 mg i.v. over 10 min), did not alter the pressor or tachycardic effects of 500 μg TRH.
- In conclusion, although plasma noradrenaline rises following i.v. TRH, suggesting activation of the sympathetic nervous system, this effect is not responsible for the pressor response to TRH, which appears to be due to either a direct vasoconstrictive effect on the peripheral resistance vessels or a direct inotropic/chronotropic effect on the heart.
109.
The Gastric Bypass for Failed Bariatric Surgical Procedures 总被引:1,自引:0,他引:1
Background: Revision of failed bariatric surgical procedures is a significant challenge for every bariatric surgeon. Methods:
Evaluated are surgical difficulties, management problems and weight loss in patients with distal gastric bypass as a revisionary
procedure. Eighty patients were followed up to 3 years; four were lost to follow-up. Mean age was 43; mean prebariatric surgery
weight 134 kg; height 1.65 meters; body mass index 40.1; ideal body weight 62.7 kg; excess weight 70.5 kg; per cent excess
weight 214%. A 250 cm stomach-to-ileocecal valve segment of small bowel was used, and the biopancreatic secretions were brought
into the terminal ileum 100 cm from the ileocecal valve. Mean pouch size was 63 cc; length of hospital stay 5 days; operative
blood loss 616 cc; operative time 130 min. Results: Intraoperative complications included three splenic injuries (without
splenectomy). Early complications included one deep vein thrombosis, two marginal ulcers, one GI hemorrhage, one wound dehiscence,
one pouch outlet obstruction and one pancreatitis. Late complications included: one death from protein malnutrition/ARDS;
21 hypoproteinemia; six protein malnutrition, and of these, three had hyperalimentation; three cholecystitis; 27 anemia; 22
incisional hernia; two staple-line disruption (reoperated); 26 low serum iron; 11 prolonged (> 6 months) diarrhea; three prolonged
frequent vomiting; and two unrelated deaths (chronic myelogenous leukemia and amyotrophic lateral sclerosis). Mean excess
weight loss was 83% at 12 months; 89% at 24 months; and 94% at 36 months. Conclusion: The distal gastric bypass is fraught
with the operative and immediate post-operative complications experienced in any revisionary bariatric surgery. Distal gastric
bypass is very effective in producing long-term weight loss. Nutritional problems are common but usually easily corrected.
The most serious nutritional complication is protein malnutrition, which must be identified and corrected early. Success of
this procedure is dependent upon patient compliance with proper nutrition and supplements, and regular office follow-up with
monitoring of laboratory data. Patients who are noncompliant are at significant risk for complications. 相似文献
110.
AN EVALUATION OF REBREATHING WITH THE BAIN SYSTEM DURING ANAESTHESIA WITH SPONTANEOUS VENTILATION 总被引:1,自引:0,他引:1
Data from 12 anaesthetized patients breathing spontaneouslyfrom the Bain system were used to calculate the degree of rebreathingoccurring when the fresh gas flowrate(F) was equal to 2,1 and 0.7 times the estimated normalminute ventilation (tot)- Measurementsof the expired minute volume (E) and end-tidal carbon dioxide tension (PE'CO2) were made to determinethe effects of this rebreathing. No rebreathing occurred whenF was equal to twice tot. When F was equal to tot rebreathing was usually small in amount and produced no changes in E or PE'CO2. Changes attributable torebreathing occurred in only two patients when F was reduced to 0.7 tot.These results are explained by the presence of anaesthesia-inducedventilatory depression and favourable changes occurring in therespiratory wave forms in the majority of patients studied.In some patients, greater values of E and rebreathing occurred in response to strong surgical stimulation.The net result of increased ventilation in these patients wasa decrease in PE'CO2-,. It is concluded that during anaesthesia,when the Bain system is used with F equal to tot, any increasein PE'CO2 which may result from rebreathing is likely to besmall and seldom of clinical importance. 相似文献