全文获取类型
收费全文 | 72046篇 |
免费 | 7492篇 |
国内免费 | 1792篇 |
专业分类
耳鼻咽喉 | 985篇 |
儿科学 | 1331篇 |
妇产科学 | 2469篇 |
基础医学 | 8227篇 |
口腔科学 | 1467篇 |
临床医学 | 10202篇 |
内科学 | 13433篇 |
皮肤病学 | 1429篇 |
神经病学 | 4939篇 |
特种医学 | 2814篇 |
外国民族医学 | 6篇 |
外科学 | 10029篇 |
综合类 | 4200篇 |
现状与发展 | 7篇 |
一般理论 | 11篇 |
预防医学 | 4699篇 |
眼科学 | 1829篇 |
药学 | 5405篇 |
20篇 | |
中国医学 | 1676篇 |
肿瘤学 | 6152篇 |
出版年
2024年 | 127篇 |
2023年 | 958篇 |
2022年 | 1390篇 |
2021年 | 2384篇 |
2020年 | 1687篇 |
2019年 | 1788篇 |
2018年 | 2666篇 |
2017年 | 2238篇 |
2016年 | 2230篇 |
2015年 | 2997篇 |
2014年 | 3704篇 |
2013年 | 4196篇 |
2012年 | 5076篇 |
2011年 | 4967篇 |
2010年 | 3478篇 |
2009年 | 3252篇 |
2008年 | 3787篇 |
2007年 | 3705篇 |
2006年 | 3578篇 |
2005年 | 3273篇 |
2004年 | 2918篇 |
2003年 | 2784篇 |
2002年 | 2447篇 |
2001年 | 2036篇 |
2000年 | 1684篇 |
1999年 | 1508篇 |
1998年 | 798篇 |
1997年 | 696篇 |
1996年 | 713篇 |
1995年 | 586篇 |
1994年 | 559篇 |
1993年 | 403篇 |
1992年 | 841篇 |
1991年 | 692篇 |
1990年 | 598篇 |
1989年 | 561篇 |
1988年 | 486篇 |
1987年 | 487篇 |
1986年 | 415篇 |
1985年 | 333篇 |
1984年 | 268篇 |
1983年 | 219篇 |
1982年 | 147篇 |
1981年 | 139篇 |
1980年 | 118篇 |
1979年 | 219篇 |
1978年 | 174篇 |
1977年 | 113篇 |
1976年 | 113篇 |
1975年 | 110篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
Thomas S. Klitzner Maggie Lee Sandra Rodriguez Ruey‐Kang R. Chang 《Congenital heart disease》2006,1(3):77-88
Background. It has been reported that gender differences in cardiovascular outcomes found in adults also are present in children who undergo surgical repair for congenital heart disease. Methods. California statewide hospital discharge data 1989–99 were used to study outcomes in children <18 years undergoing cardiac surgery. Hospital discharge data were linked to death registry data to study postdischarge death within 30 days of discharge. We used logistic regression to evaluate the effect of gender on mortality controlling for age, race and ethnicity, type of insurance, household income, date and month of surgery, type of admission, hospital case volume, and various types of procedures. Results. There were 25 402 cardiac surgery cases with 1505 in‐hospital deaths (mortality rate of 5.92%). An additional 37 deaths occurred within 30 days after hospital discharge. Crude mortality rates for males (5.99%) and females (5.84%) were not significantly different. However, fewer neonates were female and females underwent a higher proportion of low‐risk procedures than males. Logistic regression revealed that females, compared with males, had a significantly higher odds ratio (OR) for in‐hospital mortality (OR = 1.18, P < .01) and overall (up to 30 days post discharge) mortality (OR = 1.18, P < .01). The risk‐adjusted length of hospital stay was similar between females and males while charges per hospital day were slightly higher in females than males. The prevalence of Down syndrome, pulmonary hypertension, and failure to thrive were higher in females. Conclusions. Female gender is associated with an 18% higher in‐hospital and 30‐day postdischarge mortality as compared with male gender. There was no difference in length of hospital stay between males and females. The mechanism by which female gender acts as a risk factor requires further investigation. 相似文献
44.
目的:观察脑出血后血肿周围半胱氨酸天冬氨酸蛋白酶3的表达。及尼莫地平对其的影响。方法:实验于2004—07在大连医科大学中心实验室进行。取120只SD雄性大鼠随机分为3组:①尼莫地平组(n=50):尾壳核注射自体股动脉血50μL复制脑出血模型,造模即刻腹腔注射尼莫地平1.6mg/kg(即8μL/g),以后每天1次。②模型组(n=50):同前造模,术后腹腔注射等量生理盐水。③假手术组(n=20):手术,但进针人尾壳核后不注血。各组分为术后6,24,48,72h、5d 5个时间点。造模动物醒后进行Bederson评分,评估其行为和神经功能缺陷(0—3分。评分越高,神经功能缺陷越重,评分≥2分为造模成功)。人组动物在以上5个时间点进行Bederson评分后,麻醉状态下处死取脑,经尾壳核行冠状切片,行免疫组化测定半胱氨酸天冬氨酸蛋白酶3表达。结果:80只大鼠进入结果分析。①Bederson评分:模型组、尼莫地平组大鼠醒后迅速出现偏瘫,24h后评分趋于稳定,至72h之间评分最高,然后逐渐下降,5d时仍有体征。模型组、尼莫地平组各时间点评分均高于对照组(P〈0.01),尼莫地平组术后48,72h评分低于模型组(P〈0.05)。②血肿周围组织半胱氨酸天冬氨酸蛋白酶3表达:假手术组进针侧脑组织表达很少,模型组6h后即有表达,24h达高峰,持续72h后逐渐下降,5d后仅有少量表达;尼莫地平组动态变化趋势与模型组相同,但各时间点的数值均较低,尤其是术后24~72h(P〈0.01)。结论:①脑出血后血肿周围组织中半胱氨酸天冬氨酸蛋白酶3表达升高,提示其与脑出血血肿周围组织损伤有一定关系。②尼莫地平降低脑出血后血肿周围组织中半胱氨酸天冬氨酸蛋白酶3表达,从而减轻细胞凋亡程度,对神经细胞起到保护作用,降低神经功能缺陷。 相似文献
45.
46.
47.
48.
Burkitt’s lymphoma is a high-grade, rapidly growing B-cell neoplasm. It is recognized by its aggressive course, brief median survival, and low rates of long-term survival. The authors discuss the case of a patient who acutely presented with intraabdominal complications from a new onset of Burkitt’s lymphoma. The clinical and pathological features, staging, treatment options, and survival data are reviewed. In addition, the role of surgical intervention is carefully analyzed. 相似文献
49.
50.
Maher Saqqur MD Michael D. Hill MD MSc FRCPC Andrei V. Alexandrov MD Jayanta Roy MD Marcia Schebel BSc Andrea Krol BSc Zsolt Garami MD Ashfaq Shuaib MD FRCPC Andrew M. Demchuk MD FRCPC 《Journal of neuroimaging》2006,16(4):323-328
BACKGROUND: Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting. SUBJECTS AND METHODS: At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M-mode Doppler (PMD) TCD (TCD 100 M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M-mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c-lat) cerebral arteries. Ratios of aMCA/c-lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD-TCD flow findings were evaluated with a receiver-operating characteristic (ROC) analysis for angiographically proven MCA occlusion. RESULTS: We studied 120 patients with acute cerebral ischemia with PMD-TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI(95) 2.13-2.51). High resistance or absent M-mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low-resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low-resistance M-mode signatures are highly predictive of a negative angiogram for MCA occlusion. CONCLUSION: In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M-mode flow resistance signatures. Validation of these criteria will require multicenter studies. 相似文献