全文获取类型
收费全文 | 23403篇 |
免费 | 1691篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 226篇 |
儿科学 | 991篇 |
妇产科学 | 595篇 |
基础医学 | 3110篇 |
口腔科学 | 687篇 |
临床医学 | 2716篇 |
内科学 | 4562篇 |
皮肤病学 | 325篇 |
神经病学 | 1822篇 |
特种医学 | 1086篇 |
外科学 | 3129篇 |
综合类 | 410篇 |
一般理论 | 43篇 |
预防医学 | 2172篇 |
眼科学 | 349篇 |
药学 | 1421篇 |
2篇 | |
中国医学 | 16篇 |
肿瘤学 | 1479篇 |
出版年
2021年 | 331篇 |
2020年 | 235篇 |
2019年 | 368篇 |
2018年 | 406篇 |
2017年 | 337篇 |
2016年 | 338篇 |
2015年 | 436篇 |
2014年 | 592篇 |
2013年 | 774篇 |
2012年 | 1128篇 |
2011年 | 1220篇 |
2010年 | 681篇 |
2009年 | 587篇 |
2008年 | 1099篇 |
2007年 | 1177篇 |
2006年 | 1102篇 |
2005年 | 1094篇 |
2004年 | 961篇 |
2003年 | 952篇 |
2002年 | 827篇 |
2001年 | 647篇 |
2000年 | 635篇 |
1999年 | 536篇 |
1998年 | 317篇 |
1997年 | 285篇 |
1996年 | 292篇 |
1995年 | 272篇 |
1994年 | 246篇 |
1993年 | 218篇 |
1992年 | 488篇 |
1991年 | 475篇 |
1990年 | 444篇 |
1989年 | 465篇 |
1988年 | 424篇 |
1987年 | 390篇 |
1986年 | 322篇 |
1985年 | 406篇 |
1984年 | 308篇 |
1983年 | 279篇 |
1982年 | 176篇 |
1981年 | 144篇 |
1979年 | 215篇 |
1978年 | 188篇 |
1977年 | 158篇 |
1976年 | 155篇 |
1975年 | 165篇 |
1974年 | 158篇 |
1973年 | 198篇 |
1972年 | 160篇 |
1971年 | 144篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
State smoking prevalence estimates: a comparison of the Behavioral Risk Factor Surveillance System and current population surveys. 总被引:4,自引:3,他引:1 下载免费PDF全文
D R Arday S L Tomar D E Nelson R K Merritt M W Schooley P Mowery 《American journal of public health》1997,87(10):1665-1669
OBJECTIVES: This study examined whether there are systematic differences between the Behavioral Risk Factor Surveillance System (BRFSS) and the Current Population Survey (CPS) for state cigarette smoking prevalence estimates. METHODS: BRFSS telephone survey estimates were compared with estimates from the US Census CPS tobacco-use supplements (the CPS sample frame includes persons in households without telephones). Weighted overall and sex- and race-specific BRFSS and CPS state estimates of adults smoking were analyzed for 1985, 1989, and 1992/1993. RESULTS: Overall estimates of smoking prevalence from the BRFSS were slightly lower than estimates from CPS (median difference: -2.0 percentage points in 1985, -0.7 in 1989, and -1.9 in 1992/1993; P < .05 for all comparisons), but there was variation among states. Differences between BRFSS and CPS estimates were larger among men than among women and larger among Blacks than among Hispanics or Whites; for most states, these differences were not significant. CONCLUSIONS: The BRFSS generally provides state estimates of smoking prevalence similar to those obtained from CPS, and these are appropriate for ongoing state surveillance of smoking prevalence. 相似文献
62.
High-dose gadoteridol in MR imaging of intracranial neoplasms. 总被引:6,自引:0,他引:6
V M Runge J E Kirsch V J Burke A C Price K L Nelson G S Thomas B L Dean C Lee 《Journal of magnetic resonance imaging : JMRI》1992,2(1):9-18
Twelve patients with a high suspicion of brain metastases by previous clinical or radiologic examinations were studied in a phase III investigation with magnetic resonance (MR) imaging at 1.5 T after a bolus intravenous injection of 0.1 mmol/kg gadoteridol followed at 30 minutes by a second bolus injection of 0.2 mmol/kg gadoteridol. All lesions were best demonstrated (showed greatest enhancement) at the 0.3-mmol/kg (cumulative) dose, with image analysis confirming signal intensity enhancement in the majority of cases after the second gadoteridol injection. More lesions were detected with the 0.3-mmol/kg dose than with the 0.1-mmol/kg dose, and more lesions were detected with the 0.1-mmol/kg dose than on precontrast images. In this limited clinical trial, high-dose gadoteridol injection (0.3-mmol/kg cumulative dose) provided improved lesion detection on MR images specifically in intracranial metastatic disease. 相似文献
63.
64.
During a prospective evaluation of intravenous therapy with peripheral Teflon catheters in children, we found 30 episodes of phlebitis (10.4%). This rate is less than that reported in adults. Catheter colonization was not related to phlebitic episodes, and catheter-related infections did not occur. No patient's hospital course was prolonged because of phlebitis. Thirty percent of the episodes developed after the catheter was removed, and premonitory symptoms were not helpful in predicting the onset of phlebitis. Factors associated with an increased phlebitic risk were parenteral nutrition, administration of nafcillin sodium or aminoglycosides, and patient age. Parenteral nutrition prolonged the course of phlebitis. No factors hastened the onset of phlebitis. The duration of cannulation was not significantly related to phlebitis, suggesting that in some children the catheters can remain in place longer than 72 hours. 相似文献
65.
F R Nelson D Holloway A K Mohamed 《Journal of the American Mosquito Control Association》1986,2(3):296-299
In a laboratory study, the insect growth regulator, cyromazine, exerted a high level of biological activity on Aedes aegypti and Culex quinquefasciatus treated in the 4th larval instar. At 1.5 and 1.0 ppm this IGR produced 97 and 99% inhibition of emergence in adult Ae. aegypti, respectively. In Cx. quinquefasciatus, there was 99% inhibition at 1 ppm and complete inhibition at 1.5 ppm. The overall pupal mortality was higher than larval or adult stages of both species. This material induced different types of morphogenetic abnormalities in pupae and adults of the 2 species similar to those induced by other IGRs. However, most abnormalities were observed in the pupal stage. Adverse effects were not detected on the 4 mosquito predator species during the acute or posttreatment tests. 相似文献
66.
Heterotopic bone formation occurs in approximately 2% of severe burns. It occurs most frequently about the elbow and is not related to the location of the burn. Although bony encasement of the ulnar nerve is frequently found, signs and symptoms of ulnar nerve compression due to heterotopic bone have not been previously reported. Early anterior transposition of the nerve is recommended to prevent progressive neurologic loss if compressive symptoms are found in the face of developing heterotopic bone. 相似文献
67.
68.
69.
70.
Mitochondrial function and mitochondrial DNA in a series of 64 patients suspected of having mitochondrial myopathy 总被引:1,自引:0,他引:1
C Marsac F Degoul G Bonne N Romero I Nelson M Fardeau D Fran?ois G Ponsot J P Harpey B Eymard 《Revue neurologique》1991,147(6-7):462-466
Biochemical results concerning 64 patients suspected of mitochondrial myopathies are presented. Four clinical groups were studied including 21 encephalomyopathies, 42 ocular myopathies, 8 isolated myopathies and 3 cardiomyopathies. In 26 cases, the coexistence of a normal mitochondrial DNA and a mutated mitochondrial DNA (heteroplasmy) was found (19 simple deletions, 4 multiple deletions and 3 punctual mutations) and all cases presented with ocular disorders (excepted 2 cases with MERRF). Furthermore, 1 complex I deficiency (1 ocular myopathy), 1 complex IV deficiency (1 adult encephalomyopathy type Leigh), 3 complexes I + IV deficiencies (2 cases with a cardiomyopathy and 1 familial MELAS) and 2 pyruvate (1 adult from of Leigh's encephalomyopathy) dehydrogenase deficiencies (clinically and genetically different) did not show evidence of mitochondrial DNA mutation. 相似文献