全文获取类型
收费全文 | 3077篇 |
免费 | 225篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 116篇 |
妇产科学 | 30篇 |
基础医学 | 442篇 |
口腔科学 | 67篇 |
临床医学 | 279篇 |
内科学 | 629篇 |
皮肤病学 | 108篇 |
神经病学 | 111篇 |
特种医学 | 68篇 |
外科学 | 492篇 |
综合类 | 142篇 |
一般理论 | 2篇 |
预防医学 | 262篇 |
眼科学 | 84篇 |
药学 | 293篇 |
中国医学 | 37篇 |
肿瘤学 | 129篇 |
出版年
2023年 | 28篇 |
2022年 | 116篇 |
2021年 | 116篇 |
2020年 | 72篇 |
2019年 | 94篇 |
2018年 | 125篇 |
2017年 | 67篇 |
2016年 | 78篇 |
2015年 | 78篇 |
2014年 | 121篇 |
2013年 | 152篇 |
2012年 | 230篇 |
2011年 | 201篇 |
2010年 | 113篇 |
2009年 | 103篇 |
2008年 | 172篇 |
2007年 | 170篇 |
2006年 | 175篇 |
2005年 | 135篇 |
2004年 | 114篇 |
2003年 | 128篇 |
2002年 | 95篇 |
2001年 | 66篇 |
2000年 | 76篇 |
1999年 | 52篇 |
1998年 | 15篇 |
1997年 | 21篇 |
1996年 | 15篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 15篇 |
1992年 | 50篇 |
1991年 | 35篇 |
1990年 | 23篇 |
1989年 | 47篇 |
1988年 | 21篇 |
1987年 | 17篇 |
1986年 | 23篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1973年 | 7篇 |
1966年 | 4篇 |
1943年 | 4篇 |
排序方式: 共有3310条查询结果,搜索用时 15 毫秒
1.
2.
Sonoelasticity imaging of prostate cancer: in vitro results 总被引:2,自引:0,他引:2
3.
Osteoclastic inhibition: an action of nitric oxide not mediated by cyclic GMP. 总被引:18,自引:3,他引:15
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
I MacIntyre M Zaidi A S Alam H K Datta B S Moonga P S Lidbury M Hecker J R Vane 《Proceedings of the National Academy of Sciences of the United States of America》1991,88(7):2936-2940
The osteoclast is unique in its ability to resorb bone, and excessive osteoclastic activity has been implicated in osteoporosis, Paget disease of bone, rheumatoid arthritis, and the growth of metastases in bone. The activity of this cell is controlled by the main circulating inhibitor, calcitonin, in association with locally produced modulators. We show that nitric oxide (NO) may be an important member of the latter group. NO is produced by the vascular endothelium and nervous system and is involved in both neurotransmission and the regulation of blood pressure. However, our results show that the autocoid is also a potent inhibitor of osteoclast function. NO (30 microM) produced a decrease to approximately 50% of the original osteoclast spread area. Similar effects were also produced by 3-morpholinosydnonimine or sodium nitroprusside, reagents that spontaneously release NO. These shape changes were associated with a reduction of bone resorption after a 24-hr incubation of isolated osteoclasts on devitalized bone slices. NO is thought to act by stimulating guanylate cyclase, with a consequent increase in cyclic GMP, but a different mode of action is likely in the osteoclast since dibutyryl or 8-bromo cyclic GMP have no effect. It should be noted that calcitonin can produce similar changes in shape and activity but is associated with an increase in osteoclast intracellular calcium and cessation of membrane movement; neither of these is produced by NO, suggesting that its mode of action is different. The abundance of NO-producing endothelial cells in bone marrow and their proximity to osteoclasts suggests that marrow endothelial cells may play a physiological role in the regulation of osteoclastic activity. 相似文献
4.
A patient with rheumatic mitral valve stenosis and regurgitation presented with shortness of breath and a "noise" in her chest. Cardiac auscultation revealed an intermittent late systolic "whoop." An increase in severity of mitral valve insufficiency during the periods of "whoop" was observed by pulsed Doppler, hemodynamic tracings and left ventriculography. 相似文献
5.
This study investigates the association of wartime stress variables and coronary artery disease as determined by coronary angiography in Lebanon in 1986, a country with an ongoing civil war for over a decade. A total of 127 patients who underwent coronary angiography at the American University of Beirut Medical Center were individually matched on age and sex with visitor controls free from any evidence of clinical coronary artery disease. Arteriographic cases (greater than or equal to 70% maximal stenosis) were compared with two control groups: arteriographic controls (entirely normal coronaries) and visitor controls. Findings suggest that there is a relation between exposure to both acute and chronic war events and coronary artery disease in this patient population. The reporting of exposure to acute war events was significantly higher in cases compared with both visitor controls (odds ratio (OR) = 2.4, 95% confidence interval (Cl) 1.17-4.90) and arteriographic controls (OR = 2.8, 95% Cl 0.93-8.47). Crossing the "green-lines" that separate two belligerent sides, considered as an attribute of war-related chronic stress, was more frequent in cases compared with visitor controls (OR = 3.25, 95% Cl 1.54-6.89) and arteriographic controls (OR = 5.38, 95% Cl 1.65-17.6). The relation observed between wartime stress and coronary artery disease could not be explained by possible overreporting of stressful events in patients with suspected coronary artery disease or by an increase in clinical awareness for the disease for those under continuous stress. Adjusting for the effect of the well-established coronary artery disease risk factors did not alter the above findings. 相似文献
6.
7.
Antoine Alam Jacqueline Lul H l ne Coppin Nathalie Lambert Bernard Mazi res Claude De Pr val Alain Cantagrel 《Human immunology》1995,42(4):331-339
In order to look for a site-specific T-cell response in RA SM, PCR analyses using oligonucleotide primers specific for 24 TCRBV (Vβ) families were performed to compare the respective usage of each TCRBV gene by T cells present in PB and SM of 13 patients with RA. In four patients, SM cells from two or three sites of inflammation were subjected to analysis. In one patient, synovial tissue was studied at two different phases of the disease, resulting in a total number of 19 samples of SM cells, which were compared with paired samples of PB cells. The results showed that whereas all 24 TCRBV gene families could be detected in both PB and SM cells, there was some skewing of increased or decreased usage frequencies of particular TCR Vβ genes among SM cells. Three TCRBV families were often overexpressed in SM: Vβ3, Vβl7, and Vβ22. Moreover, Vβ4 was often decreased in SM (7 out of 13). This decrease was statistically significant in the RA population studied. SM from different joints of a given patient showed similar variations of T-cell repertoire compared to PB, even 6 months later in the course of the disease. These results demonstrate a biased TCRBV gene utilization in RA SM. This bias appears to be similar in different joints and at different times in the course of the disease. No correlation was found between the bias of TCR repertoire in SM and the HLA typing of these patients. 相似文献
8.
9.
M J Albert K Alam M Ansaruzzaman M M Islam A S Rahman K Haider N A Bhuiyan S Nahar N Ryan J Montanaro et al. 《Infection and immunity》1992,60(12):5017-5024
Providencia alcalifaciens is a member of the family Enterobacteriaceae. There are reports that P. alcalifaciens can cause diarrhea, but the mechanism(s) by which it causes diarrhea is known. We studied P. alcalifaciens isolated from a child and two adults with diarrhea for enteropathogenicity. The three isolates did not exhibit any characteristic adherence to cultured HEp-2 cell monolayers, and they did not produce enterotoxins, cytotoxins, or keratoconjunctivitis in the Sereny test. Two isolates invaded cultured HEp-2 cell monolayers, producing localized bacterial clusters and actin condensation. The pattern of actin condensation was different from that produced by enteropathogenic Escherichia coli but similar to that produced by Shigella flexneri. Invasion and actin condensation were poor for the third isolate. Histology of adult rabbit small intestinal loops inoculated with all three isolates revealed bacterial attachment to, penetration of, and microulcer formation on the surface epithelium and hyperemia, edema, and polymorphonuclear cell infiltration of lamina propria. All the isolates produced diarrhea in rabbits with removable intestinal ties, and some of these rabbits developed hindlimb paralysis. Intestinal histology of the rabbits with removable intestinal ties which developed diarrhea showed changes similar to that in adult rabbits on which ileal loop assays had been performed. Transmission electron microscopy of intestinal tissues also confirmed tissue penetration by the isolates. Nerve tissue histology of two rabbits that developed hindlimb paralysis showed focal mononuclear cell infiltration around peripheral nerve sheaths. It is concluded that some strains of P. alcalifaciens are enteropathogenic and that they cause diarrhea by invading the intestinal mucosal epithelium. However, the relevance to human disease of the hindlimb paralysis observed in this animal model is not clear. 相似文献
10.
M J Albert F Qadri M Ansaruzzaman A K Kibriya K Haider P K Neogi K Alam A N Alam 《Journal of clinical microbiology》1992,30(5):1341-1343
Live and boiled cells of 16 strains of Aeromonas caviae, isolated from patients with diarrhea, agglutinated with Shigella boydii 5 antiserum in a slide test. Further studies with seven selected strains showed agglutination with boiled cells in a tube test. Lipopolysaccharide antigen extracted from one of these strains cross-reacted with S. boydii 5 in enzyme-linked immunosorbent assay and immunoblot studies. Either all or the majority of the seven strains possessed properties deemed to be diarrheagenic. 相似文献