全文获取类型
收费全文 | 10292篇 |
免费 | 754篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 38篇 |
儿科学 | 289篇 |
妇产科学 | 263篇 |
基础医学 | 1268篇 |
口腔科学 | 147篇 |
临床医学 | 1347篇 |
内科学 | 2051篇 |
皮肤病学 | 158篇 |
神经病学 | 904篇 |
特种医学 | 394篇 |
外科学 | 1622篇 |
综合类 | 268篇 |
一般理论 | 8篇 |
预防医学 | 1136篇 |
眼科学 | 98篇 |
药学 | 533篇 |
中国医学 | 7篇 |
肿瘤学 | 533篇 |
出版年
2023年 | 77篇 |
2022年 | 126篇 |
2021年 | 248篇 |
2020年 | 158篇 |
2019年 | 252篇 |
2018年 | 286篇 |
2017年 | 178篇 |
2016年 | 222篇 |
2015年 | 210篇 |
2014年 | 280篇 |
2013年 | 436篇 |
2012年 | 610篇 |
2011年 | 643篇 |
2010年 | 331篇 |
2009年 | 267篇 |
2008年 | 481篇 |
2007年 | 527篇 |
2006年 | 551篇 |
2005年 | 455篇 |
2004年 | 468篇 |
2003年 | 404篇 |
2002年 | 403篇 |
2001年 | 272篇 |
2000年 | 261篇 |
1999年 | 236篇 |
1998年 | 104篇 |
1997年 | 96篇 |
1996年 | 87篇 |
1995年 | 61篇 |
1994年 | 72篇 |
1993年 | 74篇 |
1992年 | 182篇 |
1991年 | 191篇 |
1990年 | 170篇 |
1989年 | 164篇 |
1988年 | 121篇 |
1987年 | 130篇 |
1986年 | 119篇 |
1985年 | 128篇 |
1984年 | 98篇 |
1983年 | 89篇 |
1982年 | 57篇 |
1981年 | 49篇 |
1980年 | 49篇 |
1979年 | 71篇 |
1978年 | 62篇 |
1977年 | 45篇 |
1974年 | 44篇 |
1973年 | 42篇 |
1969年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
54.
To find out whether glial cells proliferate in the corpus callosum of adult mice, two series of experiments were carried out. The first one made use of 9-month-old "aged" male mice. Some of them were given 3H-thymidine as a 2-hour pulse to examine which cells became labeled and, therefore, had the ability to divide. Others were sacrificed after a continuous infusion of 3H-thymidine for 30 days to examine whether the label would then appear in different cells. In other aged animals, the 30-day infusion was followed by 60 or 180 days without 3H-thymidine to determine whether cells retained or lost their label with time. A second series of experiments was carried out in 4-month old "young adult" male mice to seek confirmation of the main conclusions. Following the 3H-thymidine pulse given to aged mice, only immature glial cells were labeled. After a 30-day infusion, 12.1% astrocytes and 1.1% oligodendrocytes were labeled, so that the net daily addition rate of astrocytes averaged 0.4% and of oligodendrocytes, 0.04%. In young adult mice, the rate after a 7-day infusion averaged 0.9% for astrocytes and 0.08% for oligodendrocytes. However, when the 30-day infusion into aged mice was followed by 60 and 180 days without 3H-thymidine, the labeled astrocytes decreased to 5.3% and 0%, respectively, whereas the number of labeled oligodendrocytes did not change significantly. The interpretation of the results is that the immature cells present in the corpus callosum of mice continue dividing throughout life and their progeny give rise to astrocytes and oligodendrocytes. In the case of astrocytes, the production of new cells occurs in parallel with a loss, so that the astrocyte population turns over. In the case of oligodendrocytes, there is a small production of new, apparently stable cells. 相似文献
55.
In the radiographical evaluation of the orbital apex syndrome, standard radiographs, tomograms, and computed tomographic scans have proved useful in the demonstration of the bony pathology, especially for optic canal fractures. The limitation of these methods, however, remains in their inability to provide accurate delineation of the associated soft tissue pathology, including the presence of optic nerve sheath hematoma. Recent developments in computer technology and graphic imaging are now available to provide an accurate three-dimensional radiographical analysis of the extent of skeletal and soft tissue injury in the orbital apex syndrome. The physician, in essence, can perform a radiographical "living autopsy". The technique was used to evaluate a patient with bilateral apex syndrome. It clearly showed that a severe direct injury to the intracanalicular portion of the optic nerve was responsible for the development of blindness in this patient. The progression of optic nerve injury, from perineural sheath hematoma to the ultimate development of optic nerve atrophy and fibrosis, was radiographically documented. 相似文献
56.
The Correlation between blood glucose level and cardio-vascular events is well established in diabetic patients. In this study, fifty three non diabetic (M:30F:23), patients after acute myocardial infarction were studied for mortality in the following two years, retrospectively. Every patient had random venous glucose estimated on admission. This glucose level was correlated with all cause mortality. At the end of 2 years, 13 patients died and 40 remained alive. There was a significant difference of blood glucose between those who died and remained alive. The difference between the mean blood glucose level is between 0.6 mmol/L and 3.8 mmol/L higher for patients who died (mean = 8.62); compared with those that were still alive (mean = 6.69). This difference was particularly observed in the group of anterior wall infarction. The subgroup analysis also revealed that the difference between the mean blood glucose levels is 9 mmol/L for female patients with heart failure compared with those who did not suffer from heart failure (mean 6.8). The study concludes that, the higher glucose level is associated with increased all cause mortality in the following 2 years of first acute myocardial infarction. 相似文献
57.
Peter H. Gilligan L. R. McCarthy Brenda K. Bissett 《Journal of clinical microbiology》1981,13(4):643-645
A case report describing Capnocytophaga ochracea (Bacteroides ochraceus) septicemia in a 21-year-old male patient receiving chemotherapy for acute lymphocytic leukemia is presented. The unusual features of this organism are discussed together with a review of the literature. 相似文献
58.
The Arabidopsis det3 mutant reveals a central role for the vacuolar H(+)-ATPase in plant growth and development 总被引:1,自引:0,他引:1 下载免费PDF全文
Schumacher K Vafeados D McCarthy M Sze H Wilkins T Chory J 《Genes & development》1999,13(24):3259-3270
In all multicellular organisms growth and morphogenesis must be coordinated, but for higher plants, this is of particular importance because the timing of organogenesis is not fixed but occurs in response to environmental constraints. One particularly dramatic developmental juncture is the response of dicotyledonous seedlings to light. The det3 mutant of Arabidopsis develops morphologically as a light-grown plant even when it is grown in the dark. In addition, it shows organ-specific defects in cell elongation and has a reduced response to brassinosteroids (BRs). We have isolated the DET3 gene by positional cloning and provide functional and biochemical evidence that it encodes subunit C of the vacuolar H(+)-ATPase (V-ATPase). We show that the hypocotyl elongation defect in the det3 mutant is conditional and provide evidence that this is due to an alternative mechanism of V-ATPase assembly. Together with the expression pattern of the DET3 gene revealed by GFP fluorescence, our data provide in vivo evidence for a role for the V-ATPase in the control of cell elongation and in the regulation of meristem activity. 相似文献
59.
Martin DJ Warren LA Gunatillake PA McCarthy SJ Meijs GF Schindhelm K 《Biomaterials》2001,22(9):973-978
This article describes a new test method for the assessment of the severity of environmental stress cracking of biomedical polyurethanes in a manner that minimizes the degree of subjectivity involved. The effect of applied strain and acetone pre-treatment on degradation of Pellethane 2363 80A and Pellethane 2363 55D polyurethanes under in vitro and in vivo conditions is studied. The results are presented using a magnification-weighted image rating system that allows the semi-quantitative rating of degradation based on distribution and severity of surface damage. Devices for applying controlled strain to both flat sheet and tubing samples are described. The new rating system consistently discriminated between the effects of acetone pre-treatments, strain and exposure times in both in vitro and in vivo experiments. As expected, P80A underwent considerable stress cracking compared with P55D. P80A produced similar stress crack ratings in both in vivo and in vitro experiments, however P55D performed worse under in vitro conditions compared with in vivo. This result indicated that care must be taken when interpreting in vitro results in the absence of in vivo data. 相似文献
60.
M Green L Sviland C E Taylor M Peiris A L McCarthy A D Pearson A J Malcolm 《Journal of clinical pathology》1992,45(9):788-790
AIMS: To detect the presence of human herpes virus 6 (HHV6) and endogenous biotin in paraffin wax embedded and frozen salivary glands. METHODS: Two stage indirect and streptavidin-biotin immunoperoxidase techniques were used to visualise the antigens. RESULTS: HHV6 could not be shown in any of the tissues. However, considerable endogenous biotin antigenicity was detected in the glandular elements of the paraffin wax embedded material. CONCLUSIONS: Results obtained with avidin-biotin detection systems should be interpreted with caution, especially when glandular epithelium is being stained. This may apply to both immunoperoxidase and in situ hybridisation techniques. The use of an anti-biotin antibody as a standard control should be considered. 相似文献