全文获取类型
收费全文 | 15802篇 |
免费 | 1386篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 143篇 |
儿科学 | 527篇 |
妇产科学 | 399篇 |
基础医学 | 2068篇 |
口腔科学 | 381篇 |
临床医学 | 1714篇 |
内科学 | 2868篇 |
皮肤病学 | 284篇 |
神经病学 | 1402篇 |
特种医学 | 576篇 |
外科学 | 2579篇 |
综合类 | 337篇 |
一般理论 | 18篇 |
预防医学 | 1388篇 |
眼科学 | 391篇 |
药学 | 1255篇 |
3篇 | |
中国医学 | 8篇 |
肿瘤学 | 896篇 |
出版年
2021年 | 221篇 |
2020年 | 142篇 |
2019年 | 232篇 |
2018年 | 257篇 |
2017年 | 186篇 |
2016年 | 225篇 |
2015年 | 268篇 |
2014年 | 371篇 |
2013年 | 530篇 |
2012年 | 754篇 |
2011年 | 830篇 |
2010年 | 422篇 |
2009年 | 398篇 |
2008年 | 665篇 |
2007年 | 688篇 |
2006年 | 692篇 |
2005年 | 590篇 |
2004年 | 584篇 |
2003年 | 586篇 |
2002年 | 483篇 |
2001年 | 467篇 |
2000年 | 503篇 |
1999年 | 412篇 |
1998年 | 208篇 |
1997年 | 141篇 |
1996年 | 168篇 |
1995年 | 150篇 |
1994年 | 133篇 |
1993年 | 144篇 |
1992年 | 397篇 |
1991年 | 357篇 |
1990年 | 365篇 |
1989年 | 347篇 |
1988年 | 349篇 |
1987年 | 317篇 |
1986年 | 303篇 |
1985年 | 333篇 |
1984年 | 259篇 |
1983年 | 211篇 |
1982年 | 148篇 |
1981年 | 125篇 |
1980年 | 123篇 |
1979年 | 235篇 |
1978年 | 172篇 |
1977年 | 124篇 |
1976年 | 117篇 |
1974年 | 119篇 |
1973年 | 128篇 |
1972年 | 112篇 |
1970年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Peter B. Richman MD Shari Dominguez MD David Kasper MD Frederick Chen MD Jeremy Friese MD Joseph Wood MD JD Joseph Collins MD Jeffrey A. Kline MD 《Academic emergency medicine》2006,13(3):295-301
Objectives: To determine interobserver agreement between radiologists for computed tomography (CT) angiography and venography. CT venography of the lower extremities combined with standard CT angiography of the chest may result in an increased overall diagnosis rate of venous thromboembolism (pulmonary embolism or deep venous thrombosis).
Methods: The study had a retrospective cohort design. The population consisted of emergency department patients who were evaluated for suspected pulmonary embolism. A random sample of 50 patients diagnosed and treated for venous thromboembolism and 50 age- and gender-matched patients whose CT angiograms and venograms were read as negative were enrolled. The original reading (R1) was compared with readings of two study radiologists: R2, a general radiologist, and R3, a radiologist with fellowship training in cross-sectional imaging. All readers were blinded to each other.
Results: Both R2 and R3 found both CT angiogram and venogram components technically adequate in 95% (95% CI = 89% to 98%) and 86% (95% CI = 78% to 92%) of studies, respectively. The agreement was very good for CT angiography (lowest agreement = 92%; lowest κ = 0.83) and was good for CT venography (85%, κ = 0.65). In nine cases, R1 read the CT angiogram as negative but the venogram as positive for DVT, whereas both R2 and R3 read both components as negative in four of these nine, suggesting a false-positive isolated DVT rate of 44% (95% CI = 19% to 73%). In no case did R1 read both scan components as negative when R2 and R3 agreed on presence of pulmonary embolism or DVT.
Conclusions: Diagnosis of pulmonary embolism on CT angiography is more reliable than diagnosis of isolated DVT on CT venography. 相似文献
Methods: The study had a retrospective cohort design. The population consisted of emergency department patients who were evaluated for suspected pulmonary embolism. A random sample of 50 patients diagnosed and treated for venous thromboembolism and 50 age- and gender-matched patients whose CT angiograms and venograms were read as negative were enrolled. The original reading (R1) was compared with readings of two study radiologists: R2, a general radiologist, and R3, a radiologist with fellowship training in cross-sectional imaging. All readers were blinded to each other.
Results: Both R2 and R3 found both CT angiogram and venogram components technically adequate in 95% (95% CI = 89% to 98%) and 86% (95% CI = 78% to 92%) of studies, respectively. The agreement was very good for CT angiography (lowest agreement = 92%; lowest κ = 0.83) and was good for CT venography (85%, κ = 0.65). In nine cases, R1 read the CT angiogram as negative but the venogram as positive for DVT, whereas both R2 and R3 read both components as negative in four of these nine, suggesting a false-positive isolated DVT rate of 44% (95% CI = 19% to 73%). In no case did R1 read both scan components as negative when R2 and R3 agreed on presence of pulmonary embolism or DVT.
Conclusions: Diagnosis of pulmonary embolism on CT angiography is more reliable than diagnosis of isolated DVT on CT venography. 相似文献
13.
14.
Development of anti-G suits and their limitations 总被引:1,自引:0,他引:1
E H Wood 《Aviation, space, and environmental medicine》1987,58(7):699-706
Initial anti-G suits were based on the belief that decreased venous return was the critical effect of increased weight of blood during acceleration. Cumbersome water filled, pneumatic gradient or pulsatile pressure suits resulted. Subsequent centrifuge studies implicated arterial pressure, rather than venous return, as the major determinant of G tolerance in the sitting position. Consequently, methods of increasing arterial pressure were developed. Findings that the hypertensive, associated anti-blackout and discomfort effects of suit inflation all increase with bladder system pressure up to arterial occlusive levels resulted in the simplified G-suit used in W.W.II to the present. Recent +Gz loss of consciousness crashes indicate current straining maneuvers plus this suit are inadequate. Furthermore, because of very high pressures to maintain cerebral circulation in the sitting position, very high G suit protection is hazardous. If piloting is essential for full use of super performance fighters, the prone position with counter-weighted head support plus omni-directional surveilance is the surest strategem to obtain this advantage. 相似文献
15.
16.
17.
M. E. Perry Y. Mustafa S. K. Wood M. I. D. Cawley D. C. Dumonde K. A. Brown 《Rheumatology international》1997,17(4):169-174
A morphological examination of synovial tissue from 25 patients with rheumatoid arthritis revealed that binucleated or multinucleated
plasma cells were present in all samples and absent in synovia obtained from 16 control patients. Plasma cells containing
two, three of four nuclei constitutet a mean 3% of the total plasma cell population. They were aways found amongst plasma
cell infiltrates and in close association with small blood vessels. Ultrastructural analysis found no evidence of cellular
membranes separating the individual nuclei in binucleated or multinucleated plasma cells, suggesting that the cells did not
arise from fusion. Some of these plasma cells had a diameter approaching 100 μm, and many were in intimate contact with macrophages.
The demonstration of a few cells with mitotic figures within the infiltrates suggests that the maintenance of plasma cell
numbers in rheumatoid synovium may depend, in part, upon their local proliferation.
Received: 25 August 1997 / Accepted: 2 October 1997 相似文献
18.
19.
Long-term survival in an infant with urethral atresia 总被引:2,自引:0,他引:2
Complete urethral atresia is an anomaly that previously was incompatible with life. We report on a surviving infant with this anomaly. As a fetus urinary decompression was accomplished with a vesicoamniotic shunt. Peritoneal dialysis was initiated shortly after birth and at 9 months supramembranous scrotal inlay urethroplasty was performed to provide for egress of urine from the bladder. A maternal renal allograft was performed when he was 12 months old. When the patient was 3 1/2 years old he had normal renal function and emptied the bladder to completion through the reconstructed urethra. Although mildly delayed, he continues to progress with all developmental milestones. 相似文献
20.
Variation amongst Achromobacter-like strains was examined by DNA restriction endonuclease digestion and rDNA gene patterns generated using a non-radioactive probe. Chromosomal DNA was extracted from 12 cultures representing Achromobacter groups B, E and F, all from human blood cultures. DNA fingerprinting using EcoRI, Hae III or HindIII sub-divided the strains in a similar manner to that obtained by their protein patterns. The HaeIII patterns, with their small number of bands, were the easiest to interpret. The EcoRI patterns included a species-species triplet of bands but minor band patterns allowed further differentiation. The Achromobacter group F strains comprised a separate taxon and were distinct from the group B and E strains by all techniques examined. The study demonstrates that, in addition to total DNA digest analysis, rDNA gene restriction patterns provide a simple but discriminatory electrophoretic method for distinguishing within Achromobacter groups B and E. 相似文献