全文获取类型
收费全文 | 12914篇 |
免费 | 1214篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 81篇 |
儿科学 | 446篇 |
妇产科学 | 353篇 |
基础医学 | 1735篇 |
口腔科学 | 369篇 |
临床医学 | 1538篇 |
内科学 | 2486篇 |
皮肤病学 | 128篇 |
神经病学 | 1047篇 |
特种医学 | 427篇 |
外科学 | 1952篇 |
综合类 | 382篇 |
一般理论 | 11篇 |
预防医学 | 1530篇 |
眼科学 | 139篇 |
药学 | 827篇 |
中国医学 | 8篇 |
肿瘤学 | 696篇 |
出版年
2021年 | 179篇 |
2020年 | 107篇 |
2019年 | 192篇 |
2018年 | 219篇 |
2017年 | 169篇 |
2016年 | 172篇 |
2015年 | 208篇 |
2014年 | 263篇 |
2013年 | 408篇 |
2012年 | 601篇 |
2011年 | 626篇 |
2010年 | 319篇 |
2009年 | 312篇 |
2008年 | 521篇 |
2007年 | 596篇 |
2006年 | 527篇 |
2005年 | 509篇 |
2004年 | 490篇 |
2003年 | 452篇 |
2002年 | 442篇 |
2001年 | 407篇 |
2000年 | 496篇 |
1999年 | 432篇 |
1998年 | 148篇 |
1997年 | 133篇 |
1996年 | 159篇 |
1995年 | 158篇 |
1994年 | 128篇 |
1993年 | 126篇 |
1992年 | 316篇 |
1991年 | 318篇 |
1990年 | 341篇 |
1989年 | 289篇 |
1988年 | 257篇 |
1987年 | 252篇 |
1986年 | 235篇 |
1985年 | 246篇 |
1984年 | 170篇 |
1983年 | 138篇 |
1980年 | 92篇 |
1979年 | 153篇 |
1978年 | 126篇 |
1977年 | 101篇 |
1976年 | 100篇 |
1975年 | 96篇 |
1974年 | 124篇 |
1973年 | 116篇 |
1972年 | 116篇 |
1971年 | 114篇 |
1970年 | 104篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
A severe anaemia was diagnosed in a 7-month-old female cat. Most erythrocytes contained unusually large Heinz bodies and showed marked distortion. Six weeks later, the cat had recovered from the anaemia, but the erythrocytes still contained smaller inclusions. By light microscopy, these inclusions did not stain as typical Heinz bodies, but, by electron microscopy, Heinz bodies and autophagocytic vacuoles were identified. It is suggested that this cat had a pre-existing defect in its haemoglobin which made it more susceptible to damage by an unknown oxidizing agent. 相似文献
102.
A simple visual observation system, supplemented by measurement of skin potential, was devised for developmental studies of sleep cycles in settings where multiple electrode placement is not practicable. The findings replicated essential features of quiet and active sleep cycles which had been reported previously to exist against the background of decreasing level of physiological arousal, as sleep proceeds. Twelve newborns showed approximately one-half of their inter-feeding sleeping time in the rapid eye movement stage of sleep. Skin potential rapidly declined from the waking level, continued to decrease in level throughout sleep, increased in variability during REM sleep, and increased in level at the second waking period. 相似文献
103.
104.
In the event of smallpox bioterrorism, widespread vaccination may be required. Vaccinia immune globulin (VIG) has been used to treat complications from the smallpox vaccine. While the potency of VIG was defined by its ability to neutralize intracellular mature virus, a second form of vaccinia called the extracellular enveloped virus (EEV) is critical for virus spread in the host. The B5R-protein is one of many EEV-specific proteins. Immunoprecipitation and ELISA revealed that VIG recognizes the B5R-protein. An EEV plaque-reduction assay using a recombinant vaccinia that lacks the majority of the extracellular domain of B5R showed that the ability of VIG to neutralize EEV is principally directed at B5R. In addition, absorbing out the anti-B5R antibody present in VIG through the addition of recombinant B5R protein abrogated VIG's ability to significantly neutralize wild-type EEV. This work demonstrates the prominent role of B5R as a target of EEV-neutralizing activity of human antibodies. 相似文献
105.
Previously published data have indicated that in the rat, unlike other species examined, the kidney is not supplied by sensory nerves containing substance P (SP). As part of a study of reflex control of renal function in the rat, we have now reassessed this situation. Many fine, varicose, SP-immunoreactive nerve fibers were found in the wall of the proximal ureter and the renal pelvis, and around the larger renal blood vessels. Sparser populations of similar nerves were also seen running close to proximal and distal tubules in the renal cortex. Occasional fibers were seen at the margins of the glomeruli. Our findings suggest that sensory nerves containing SP may carry sensory information of several types from the rat kidney. 相似文献
106.
Calcitonin gene-related peptide (CGRP) and substance P (SP) immunoreactivity were investigated in the superior cervical ganglion of normotensive and genetically hypertensive Otago Wistar rats by an immunoperoxidase method. CGRP- and SP-positive varicose axons invested separate subpopulations of ganglion cells, neither of which contained neuropeptide Y. The densities of CGRP axons were similar in normotensive and hypertensive rats while the numbers of SP axons were several times higher in the hypertensive strain. Decentralization of the ganglion or chronic capsaicin treatment removed all immunoreactive terminals, indicating that both axon populations are likely to be collaterals from thoracic sensory afferents. 相似文献
107.
Cost effectiveness of vaccination against pneumococcal pneumonia 总被引:5,自引:0,他引:5
J S Willems C R Sanders M A Riddiough J C Bell 《The New England journal of medicine》1980,303(10):553-559
We used cost-effectiveness analysis to examine the medical-care costs of vaccination against pneumococcal pneumonia in relation to its effects on health. Vaccination could add a year of healthy life among all age groups for about $4,800 in net medical-care costs. Cost-effectiveness ratios vary according to the age of the person vaccinated--from $1,000 per year of healthy life for an adult 65 years old or older to $77,000 per year of healthy life for a child between the ages of two and four. These ratios may change substantially with variations in such factors as the cost of vaccination, the duration of immunity, the efficacy and composition of the vaccine, and the percentage of pneumonia that is pneumococcal. This analysis has particular relevance for the Medicare program, since present legislation excludes coverage of most immunizations and other preventive services. Provision of pneumococcal vaccine to the elderly and inclusion of the vaccine as a Medicare benefit merit serious consideration. 相似文献
108.
Micropuncture studies in dogs have suggested that a distal tubule-to-afferent arteriole feedback system may participate in the autoregulation mechanism at the single-nephron level. To evaluate the effect of interrupted distal delivery on glomerular capillary pressure (GP) and its autoregulation, the proximal tubule was blocked with oil and maximal stop-flow pressure was measured with a micropressure servo-null system. The GP was estimated from the sum of stop-flow pressure and the plasma colloid osmotic pressure (membrane oncometer). In 18 dogs given a mild mannitol load, average +/- SD control arterial pressure was 118 +/- 16 mmHg, proximal tubule pressure was 24 +/- 5 mmHg, and estimated GP averaged 70 +/- 10 mmHg. There was a highly significant relationship between estimated GP and arterial blood pressure. Similar results were obtained in hydropenic dogs. In response to decreases in renal arterial pressure in individual dogs, stop-flow pressure and estimated GP failed to exhibit autoregulation although autoregulation of renal blood flow, GFR, and proximal tubule pressure was observed over an arterial pressure range of 150-95 mmHg. These results indicate that interruption of normal distal delivery by proximal tubule blockage interferes with the ability of the nephron to autoregulate glomerular pressure. They provide further evidence in support of the concept that a distal tubular feedback mechanism participates, at least in part, in the autoregulatory control of glomerular pressure. 相似文献
109.
110.
M C Roberts T A Bell K I Sandstrom A L Smith K K Holmes 《Journal of medical microbiology》1986,21(3):219-224
Haemophilus strains isolated from children under the age of 11 months with conjunctivitis were characterised by biotype, sugar fermentation, plasmid pattern and outer-membrane-protein profiles. H. influenzae was the most common species identified and was separated into 14 groups based on sugar fermentation and biotype patterns and into more than 20 groups when plasmid and outer-membrane-protein profiles were included. Small (mol. wt less than 10 X 10(6)) plasmids were identified in 11 of 34 (32%) H. influenzae isolates, 1 of 2 H. haemolyticus and 4 of 6 (67%) H. parainfluenzae isolates. Examination of sugar-fermentation and plasmid patterns increased the ability to distinguish between strains isolated at different times from recurrent disease and may have general applications in the study of Haemophilus strains isolated from a single anatomical site. 相似文献