全文获取类型
收费全文 | 7519篇 |
免费 | 398篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 101篇 |
儿科学 | 132篇 |
妇产科学 | 46篇 |
基础医学 | 1009篇 |
口腔科学 | 177篇 |
临床医学 | 653篇 |
内科学 | 1571篇 |
皮肤病学 | 149篇 |
神经病学 | 439篇 |
特种医学 | 409篇 |
外国民族医学 | 1篇 |
外科学 | 1234篇 |
综合类 | 40篇 |
一般理论 | 1篇 |
预防医学 | 175篇 |
眼科学 | 321篇 |
药学 | 583篇 |
中国医学 | 25篇 |
肿瘤学 | 886篇 |
出版年
2023年 | 35篇 |
2022年 | 85篇 |
2021年 | 137篇 |
2020年 | 91篇 |
2019年 | 113篇 |
2018年 | 168篇 |
2017年 | 119篇 |
2016年 | 140篇 |
2015年 | 151篇 |
2014年 | 202篇 |
2013年 | 215篇 |
2012年 | 320篇 |
2011年 | 348篇 |
2010年 | 205篇 |
2009年 | 175篇 |
2008年 | 330篇 |
2007年 | 322篇 |
2006年 | 338篇 |
2005年 | 295篇 |
2004年 | 344篇 |
2003年 | 312篇 |
2002年 | 323篇 |
2001年 | 293篇 |
2000年 | 275篇 |
1999年 | 244篇 |
1998年 | 93篇 |
1997年 | 71篇 |
1996年 | 66篇 |
1995年 | 57篇 |
1994年 | 62篇 |
1993年 | 55篇 |
1992年 | 174篇 |
1991年 | 160篇 |
1990年 | 175篇 |
1989年 | 163篇 |
1988年 | 160篇 |
1987年 | 112篇 |
1986年 | 105篇 |
1985年 | 136篇 |
1984年 | 90篇 |
1983年 | 69篇 |
1982年 | 38篇 |
1981年 | 35篇 |
1980年 | 39篇 |
1979年 | 68篇 |
1978年 | 48篇 |
1975年 | 36篇 |
1971年 | 37篇 |
1970年 | 40篇 |
1969年 | 40篇 |
排序方式: 共有7952条查询结果,搜索用时 0 毫秒
101.
The antitumor effects of vitamin K2 were studied using three glioma cell lines: C6 (rat glioma cell), RBR17T and T98G (human glioma cell). The antitumor effects were estimated by count assay. The results was that vitamin K2 induced growth inhibition in a dose-dependent manner. The RBR 17T cells exposed to vitamin K2 for 72 hours resulted in oligonucleosomal DNA fragmentation and formed a ladder on agarose gel electrophoresis. Furthermore, the RBR17T cells exposed to vitamin K2 for 24 hours were significantly accumulated in the G0G1 phase of the cell cycle. Those results suggested that vitamin K2 can inhibit the proliferation of cells through the induction of cell cycle arrest and apoptosis for tumor cells. The combined treatment of vitamin K2 with ACNU or 5-FU or INF-beta or 1,25-dihydroxyvitamin D3 enhanced growth inhibition significantly. In conclusion, vitamin K2 can be a useful drug for the treatment of glioma. 相似文献
102.
Effectiveness of portable toothbrush use on reducing cigarette consumption and improving oral health
There have been many studies on the influence of smoking on health, and in recent years, there have also been studies examining the relationship between smoking and oral health, concluding that smoking has a considerable detrimental effect on oral health. We introduced in a number of companies the idea of "Non smoking through the use of a portable toothbrush" as a means of giving up smoking while at the same time promoting oral health. The results demonstrated that consumption of cigarettes was reduced in about 50 percent of cases, while some improvement in mouth freshness was seen in about 90 percent. The study also showed that the success rate in reducing cigarette consumption through the use of a portable toothbrush was higher in highly motivated subjects, leading us to conclude that motivation is a major factor in reducing cigarette consumption. The study impressed on us the importance of educating people on the effect of smoking on oral health and the possibility of using a portable toothbrush as a means of reducing smoking. 相似文献
103.
M Ishizaki Y Yamada Y Morikawa Y Noborisaka M Ishida K Miura H Nakagawa 《Occupational medicine (Oxford, England)》1999,49(3):177-182
As a marker of body fat distribution and therefore level of obesity, the waist-to-hip ratio (W:H) is a good indicator of coronary heart disease risk status. The present study investigated the association between occupational status and life-style factors, and W:H of middle-aged Japanese male (n = 2,550) and female (n = 1,283) workers in a metal-products factory. A higher W:H was observed in the management level males as compared with the other male workers and we suggest this was promoted by the sedentary aspect of their work, as well as their higher levels of alcohol consumption and lower levels of leisure-time physical activity. In contrast, a higher W:H was recorded in female labourers, whose work was typically less sedentary as compared with female managers. Life-style factors included in the study were not related to this observation. We conclude that other unmeasured psychosocial factors may be important in promoting higher W:H in female labourers. 相似文献
104.
Morphological analysis of the cervical spinal canal,dural tube and spinal cord in normal individuals using CT myelography 总被引:3,自引:0,他引:3
To verify the conventional concept of developmental stenosis of the cervical spinal canal, we performed a morphological analysis of the relations of the cervical spinal canal, dural tube and spinal cord in normal individuals. The sagittal diameter, area and circularity of the three structures, and the dispersion of each parameter, were examined on axial sections of CT myelograms of 36 normal subjects. The spinal canal was narrowest at C4, followed by C5, while the spinal cord was largest at C4/5. The area and circularity of the cervical spinal cord were not significantly correlated with any parameter of the spinal canal nor with the sagittal diameter and area of the dural tube at any level examined, and the spinal cord showed less individual variation than the bony canal. Compression of the spinal cord might be expected whenever the sagittal diameter of the spinal canal is below the lower limit of normal, that is about 12 mm on plain radiographs. Thus, we concluded that the concept of developmental stenosis of the cervical spinal canal was reasonable and acceptable. 相似文献
105.
Ishida Y Hashiguchi H Ishizuka Y Todaka K Kuwahara I Mitsuyama Y Nishimori T 《The European journal of neuroscience》2000,12(2):771-775
Basal expression of the protein products of the inducible immediate early genes (IEGs), c-Fos and Zif268, was investigated in five regions of the rat basal ganglia using immunohistochemistry. In particular, high basal levels of Zif268 but very low levels of c-Fos were seen in the caudate-putamen (CPu). Double immunostaining revealed that many of the constitutively expressed Zif268-positive neurons were GABAergic but very few were cholinergic or neuronal nitric oxide synthase (nNOS)-positive, and some of the Zif268-positive neurons were also immunopositive for a glutamate NMDA receptor subunit NR1 or NR2A. No regional difference between the medial and lateral parts of the CPu was observed in the cellular phenotypes of Zif268-positive neurons. Almost no basal levels of Zif268 were seen in the other four regions: the globus pallidus, entopeduncular nucleus, subthalamic nucleus and substantia nigra pars reticulata. As in the CPu, negligible levels of c-Fos were seen in these four regions. Differential expression of these two IEGs may suggest gene-specific and region-specific functions of c-Fos and Zif268 in the basal ganglia. Constitutive expression of Zif268 existing mainly in the GABAergic neurons in the CPu may at least in part be maintained by glutamatergic afferents. 相似文献
106.
Ishida H Koyama I Sawada T Murakami T Utsumi K Sannomiya A Tsuji K Tojimbara T Nakajima I Tanabe K Fuchinoue S Yamaguchi Y Toma H Agishi T 《Transplantation》2000,69(1):59-63
BACKGROUND: In organ transplantation, the grafts must be carefully monitored, but it is often difficult to make a quick and accurate diagnosis of unusual changes. Extensive research has failed to identify a useful marker for rejection. We investigated the clinical utility of sialyl Lewis(X) (CD15s) monitoring in 17 renal transplant patients with acute rejection. METHODS: The expression of CD15s on peripheral lymphocytes was examined using flow cytometry in renal transplant recipients with rejection (n=17), without rejection (n=23), recipients infected with cytomegalovirus (n=7), recipients with other diseases (n=7), and healthy volunteers (n=18). CD15s expression was compared with histological findings, and was also examined before and after steroid pulse therapy to investigate the effects of steroids on CD15s antigen expression on the surface of the peripheral lymphocytes. RESULTS: CD15s was strongly expressed in all patients with rejection, but was not expressed in any of the patients without rejection or in any healthy volunteers. Histologically, cell infiltration into the rejected graft was moderate or severe in all patients with strong expression of CD15s. In contrast, no or only mild infiltration was observed in patients with weak expression of CD15s. In addition, 14 of 17 patients (14/17, 82%) with strong CD15s expression improved upon administration of steroid pulse therapy, although there was no benefit from steroids in any of the patients with weak expression of CD15s. CONCLUSIONS: The CD15s antigen is expressed strongly on the peripheral lymphocytes at the time of rejection. It is interesting that the efficacy of steroid therapy in the patients with elevated creatinine could be predicted by CD15s expression on the peripheral lymphocytes before graft biopsy. There have been only few reports showing the relationship between CD markers and the efficacy of the treatment in patients with elevated creatinine. We report that the detection of CD15s on the peripheral lymphocytes by flow cytometry was an easy, helpful, and noninvasive means for the diagnosis and treatment of patients with elevated creatinine after renal transplantation. 相似文献
107.
Murakami T Kikugawa D Endou K Fukuhiro Y Ishida A Morita I Masaki H Inada H Fujiwara T 《Artificial organs》2000,24(12):953-958
In this study, we analyzed the extent and pattern of regression of left ventricular (LV) hypertrophy after aortic valve replacement in patients with aortic stenosis (AS) and compared the results with those of another group of patients with aortic regurgitation (AR). Seventy patients who underwent isolated aortic valve replacement were divided into 2 groups. Group 1 was comprised of 29 patients who underwent aortic valve replacement for aortic stenosis, and Group 2 of 41 patients who underwent aortic valve replacement for aortic regurgitation. A third group of 10 healthy subjects served as a healthy control group. Echocardiographic studies were done before the operation and 5 years postoperatively. At follow-up, a significant reduction in the left ventricular mass was found in both groups, but it remained significantly greater than in the healthy control group. The ratio of LV wall thickness to radius (th/r) in Group 1 decreased significantly, and at follow-up it was within the normal value. In Group 2, the th/r ratio increased, and at follow-up it was within the normal value. After aortic valve replacement, the wall thickness remained significantly greater than normal for patients with AS, and the chamber radius remained significantly greater than normal for patients with AR. For these reasons, LV hypertrophy still existed in both groups at postoperative follow-up. The actuarial survival rate was 85.3% at 16 years for Group 1 and 83.4% at 18 years for Group 2. There was no significant difference in the long-term survival rates between the 2 groups. Actuarial freedom from valve-related events was 91.9% at 16 years for Group 1 and 82% at 18 years for Group 2. There was no significant difference in the valve-related event free curves between groups. After 5 years of follow-up, th/r reached normal for both groups, indicating remodeling of the LV geometry after aortic valve replacement. 相似文献
108.
OBJECTIVE: In benign prostatic hyperplasia (BPH), it is uncertain whether the size of the prostate is related to the degree of urodynamically demonstrated bladder outlet obstruction. We compared MR imaging findings and urodynamic data in patients with surgically confirmed BPH. MATERIALS AND METHODS: We prospectively studied 43 benign prostatic hyperplasia (BPH) patients in whom transurethral resection of the prostate (TURP) was planned. We obtained T1- and T2-weighted images in the transverse and sagittal planes with a 1.5 Tesla superconducting unit. The predicted volume of the inner gland and the peripheral zone were obtained on T2-weighted transverse images. Prostatic protrusion into the urinary bladder (IB protrusion) and the inner gland ratio (IG ratio: inner gland volume/total prostatic volume) were determined. RESULTS: IB protrusion and inner IG ratio were significantly greater in patients with severe stenosis than in those without. A surgical capsule (SC) was seen in 20 of 25 patients (80%) with severe stenosis and 8 of 18 (44%) of those without it. The accuracy of IB protrusion + IG ratio, IB protrusion + surgical capsule, and IB protrusion + IG ratio + surgical capsule was 89%, and that of IG ratio + surgical capsule was 86%. CONCLUSION: The inner gland ratio, protrusion into the bladder, and presence of surgical capsule were the most important factors in bladder outlet obstruction. The probability of outlet stenosis increases in patients with more than two of these criteria. 相似文献
109.
Soapfishes contain peptide toxins (grammistins) in the skin secretion. Two grammistins (Gs 1 and Gs 2) and six grammistins (Pp 1, Pp 2a, Pp 2b, Pp 3, Pp 4a and Pp 4b) have already been isolated from Grammistes sexlineatus and Pogonoperca punctata, respectively. In this study, five grammistins (Gs A-E), together with grammistins Gs 1 and Gs 2, were further isolated from G. sexlineatus by gel filtration and reverse-phase HPLC. Sequence analyses revealed that grammistins Gs A (28 residues) and Gs C (26 residues) are analogous to grammistin Pp 3 and grammistin Gs B (12 residues) to grammistin Pp 1, while grammistins Gs D (13 residues) and Gs E (13 residues) are identical with grammistins Pp 1 and Pp 2b, respectively. Grammistins Gs A-C exhibited antibacterial activity with a broad spectrum against nine species of bacteria in common with the other grammistins but had no hemolytic activity differing from the other grammistins. Grammistins Gs A-E, Gs 1 and Gs 2 could release carboxyfluorescein entrapped within liposomes made of either phosphatidylcholine or phosphatidylglycerol/phosphatidylcholine (3:1), demonstrating their membrane-lytic activity. However, no clear relationship between the membrane-lytic activity and the biological activity of grammistins was recognized. 相似文献
110.
Tetsuya Shirokawa Yoshiyuki Ishida Wataru Matsunaga Sadamu Nakai Ken-ichi Isobe 《Nihon shinkei seishin yakurigaku zasshi》2005,25(1):43-48
The locus coeruleus (LC), located within the caudal pontine central gray, is composed of noradrenaline-containing neurons. The axons of these neurons form extensive collateral branches that project widely to many brain sites. The function of the LC is still unclear at present, however, LC neurons are known to exhibit marked axonal regeneration and sprouting in response to brain damage. We investigated the age-related changes in noradrenergic innervations of the frontal cortex, using in vivo electrophysiological techniques and immunohistochemistry. While noradrenergic innervations gradually decreased with age in the frontal cortex, a high degree of sprouting occurred in the LC axon terminals in middle age. Neither the electrophysiological properties of LC neurons nor NA levels in the frontal cortex changed with age. These findings suggested that the LC neurons preserve a strong capacity to remodel their axon terminals even in the aging brain. Exogenous brain-derived neurotrophic factor (BDNF) infusion caused a marked increase in the density of noradrenergic axon in the aged brain, but no trophic action of BDNF was observed in the young or middle-aged brain. The result suggests that BDNF is necessary for the maintenance of noradrenergic innervations in the aged brain. 相似文献