全文获取类型
收费全文 | 35441篇 |
免费 | 2626篇 |
国内免费 | 152篇 |
专业分类
耳鼻咽喉 | 322篇 |
儿科学 | 1081篇 |
妇产科学 | 851篇 |
基础医学 | 4395篇 |
口腔科学 | 446篇 |
临床医学 | 3443篇 |
内科学 | 7508篇 |
皮肤病学 | 770篇 |
神经病学 | 2792篇 |
特种医学 | 1221篇 |
外国民族医学 | 1篇 |
外科学 | 5556篇 |
综合类 | 662篇 |
一般理论 | 62篇 |
预防医学 | 2888篇 |
眼科学 | 956篇 |
药学 | 2483篇 |
3篇 | |
中国医学 | 106篇 |
肿瘤学 | 2673篇 |
出版年
2023年 | 169篇 |
2022年 | 251篇 |
2021年 | 566篇 |
2020年 | 367篇 |
2019年 | 537篇 |
2018年 | 676篇 |
2017年 | 542篇 |
2016年 | 585篇 |
2015年 | 675篇 |
2014年 | 998篇 |
2013年 | 1367篇 |
2012年 | 2060篇 |
2011年 | 2152篇 |
2010年 | 1216篇 |
2009年 | 1109篇 |
2008年 | 1981篇 |
2007年 | 2111篇 |
2006年 | 2055篇 |
2005年 | 2124篇 |
2004年 | 2050篇 |
2003年 | 1882篇 |
2002年 | 1834篇 |
2001年 | 774篇 |
2000年 | 647篇 |
1999年 | 650篇 |
1998年 | 445篇 |
1997年 | 455篇 |
1996年 | 396篇 |
1995年 | 358篇 |
1994年 | 311篇 |
1993年 | 272篇 |
1992年 | 445篇 |
1991年 | 392篇 |
1990年 | 358篇 |
1989年 | 341篇 |
1988年 | 314篇 |
1987年 | 298篇 |
1986年 | 278篇 |
1985年 | 283篇 |
1984年 | 263篇 |
1983年 | 275篇 |
1982年 | 281篇 |
1981年 | 278篇 |
1980年 | 230篇 |
1979年 | 233篇 |
1978年 | 207篇 |
1977年 | 198篇 |
1976年 | 142篇 |
1975年 | 149篇 |
1974年 | 170篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
To examine the prevalence of Internet sex networking among men who have sex with men (MSM) in Hong Kong and risk behaviors associated with the behavior, a telephone survey of 15,230 Hong Kong Chinese men aged 18-60 was conducted. Of the 283 active MSM (having engaged in some MSM behaviors in the last 6 months) identified, 17.7% had networked for MSM partners via the Internet in the last 6 months. Younger age (odds ratio [OR] for age < or = 25 vs. age >25 = 4.67, 95% confidence interval [CI] = 2.35-9.28) and being an anal-sex MSM (OR = 4.72, 95% CI=2.36-9.44) were independent predictors of Internet sex networking. Being an Internet sex networker was associated with some risk behaviors such as having contracted a sexually transmitted disease (adjusted OR = 4.79, 95% CI = 1.34-17.11), having had > or = 3 MSM partners (adjusted OR = 4.74, 95% CI = 2.20-10.23), and having engaged in anal sex (adjusted OR = 3.95, 95% CI = 1.89-8.23). HIV prevention programs for MSM should thereby include Internet-based interventions. 相似文献
3.
4.
Juvenile hypocalcemia provokes persistent electroencephalographic change in renally compromised rats
J J Lipman D L White P L Lawrence P E Teschan 《Journal of the American College of Nutrition》1988,7(6):453-460
In view of the putative involvement of calcium in uremic encephalopathy and the critical importance of this element in juvenile development, we examined the effect of temporary restriction of dietary calcium intake on serum chemistry and the quantitative electroencephalogram (Q.EEG) in unilaterally 3/4 nephrectomized juvenile male Sprague-Dawley rats. Animals were renally infarcted at 22-26 days of age (50-74 g) and placed on one of two isocaloric dietary regimens: powdered normal rat diet (ND, n = 25) or low calcium diet (LCD, n = 8) for 30 days. At this time, ND animals showed normal serum chemistries, whereas LCD rats were hypocalcemic and azotemic with significantly elevated blood urea nitrogen (BUN) and serum creatinine concentrations and reduced renal creatinine clearance values. All animals thereafter received ND for 25-34 further days, during which time chronic Q.EEG electrodes were implanted. At the end of the common ND feeding period, serum chemistry values were equal and normal in both groups. The average theta/alpha ratio (TAR) of the overnight Q.EEG was assessed for 3 days. We found that the TAR of previously LCD animals was significantly elevated compared with ND rats. This indicates an encephalopathic slowing of the background rhythm of these animals. We conclude that, following restoration of a transient uremic and hypocalcemic episode induced by LCD feeding, the Q.EEG background frequency of juvenile renally impaired rats was abnormally slow after 30 days of ND feeding. 相似文献
5.
OBJECTIVE: Cancer Care Ontario has recommended a population-based colorectal cancer (CRC) screening program using fecal occult blood testing. Patients who test positive should undergo further investigation, preferably colonoscopy. So far, no studies have been performed to quantify the costs or demands on the health care system at the community level. The number of consultations, colonoscopies and polypectomies, and the corresponding direct medical costs generated by the CRC screening program, between 2006 and 2015 in London, Ontario, were estimated using a decision analysis model in comparison with the population health model. METHODS: A faxed survey study was conducted to examine the current CRC screening practice among family physicians in London. Data from the survey and randomized studies were applied to a decision analysis model, which simulated the steps involved in population-based biennial and annual CRC screening between 2006 and 2015. The number of consultations, colonoscopies and polypectomies, and their associated costs were calculated. RESULTS: For a cohort population of 140,000, between 50 and 74 years of age, in 2006 to 2015, it is estimated that an average of 412 consultations, 463 colonoscopies and 174 polypectomies will be performed per 100,000 screen eligible population per year in biennial screening, and double in annual screening, reflecting an average of 8.7% or 17.6% increase annually in outpatient colonoscopies, respectively, compared with 2003. A mean of $285,000 or $562,000 per year would be required to support the extra consultation and endoscopic procedures generated by the biennial or annual screening. CONCLUSION: Population-based fecal occult blood testing screening for CRC appears to be a manageable strategy if a modest increase in endoscopic resources is allocated. 相似文献
6.
7.
Lawrence S Prince Heather I Dieperink Victor O Okoh German A Fierro-Perez Roger L Lallone 《Developmental dynamics》2005,233(2):553-561
We tested the hypothesis that innate immune signaling in utero could disrupt the structural development of the fetal lung, contributing to the pathogenesis of bronchopulmonary dysplasia. Injection of Escherichia coli lipopolysaccharide (LPS) into the amniotic fluid of E15 BALB/cJ mice increased the luminal volume density of fetal mouse lungs at embryonic day (E) 17 and E18. LPS also increased luminal volume and decreased distal lung branching in fetal mouse lung explants. This effect required NF-kappaB activation and functional Toll-Like Receptor 4. Airway branching may require fibronectin-dependent epithelial-mesenchymal interactions, representing a potential target for innate immune signaling. Anti-fibronectin antibodies and LPS both blocked distal lung branching. By immunofluorescence, fibronectin localized to the clefts between newly formed airways but was restricted to peripheral mesenchymal cells in LPS-exposed explants. These data suggest that LPS may alter the expression pattern of mesenchymal fibronectin, potentially disrupting epithelial-mesenchymal interactions and inhibiting distal airway branching and alveolarization. This mechanism may link innate immune signaling with defects in structural development of the fetal lung. 相似文献
8.
9.
10.
Dr. Rex O. Brown Pharm.D. Dr. Roland N. Dickerson Pharm.D. Dr. Emily B. Hak Pharm.D. Dr. J. Barret Matthews M.D. Dr. Lawrence J. Hak Pharm.D. 《Pharmacotherapy》1997,17(4):796-800
A pharmacist consult service was developed to evaluate the appropriateness of enteral feeding through a permanent ostomy in 24 nonambulatory patients with severe developmental disabilities. Several problems with enteral nutrition were identified. Policies to improve them were instituted, and several educational presentations were made. Pharmacists' actions were implemented, including assessment of energy needs by indirect calorimetry and rearrangement of enteral feeding schedules to achieve optimal nutrition support and pharmacotherapy administration. By the fourth month of the consult service, body weight in these patients increased from 101 ± 6% of baseline to 109 ± 7% (p<0.05). Weight continued to increase through the seventh month of the consult service to 116 ± 12% of baseline (p<0.0001). Measured resting energy expenditure for the group was 889 ± 170 kcal/day compared with the predicted 1055 ± 163 kcal/day. 相似文献