全文获取类型
收费全文 | 102240篇 |
免费 | 9282篇 |
国内免费 | 6335篇 |
专业分类
耳鼻咽喉 | 1247篇 |
儿科学 | 1237篇 |
妇产科学 | 957篇 |
基础医学 | 11924篇 |
口腔科学 | 1788篇 |
临床医学 | 11476篇 |
内科学 | 14180篇 |
皮肤病学 | 1641篇 |
神经病学 | 4970篇 |
特种医学 | 4708篇 |
外国民族医学 | 25篇 |
外科学 | 10217篇 |
综合类 | 17571篇 |
现状与发展 | 33篇 |
一般理论 | 8篇 |
预防医学 | 7493篇 |
眼科学 | 2720篇 |
药学 | 11357篇 |
98篇 | |
中国医学 | 5839篇 |
肿瘤学 | 8368篇 |
出版年
2024年 | 308篇 |
2023年 | 1341篇 |
2022年 | 3382篇 |
2021年 | 4670篇 |
2020年 | 3462篇 |
2019年 | 3019篇 |
2018年 | 3163篇 |
2017年 | 3104篇 |
2016年 | 3085篇 |
2015年 | 4769篇 |
2014年 | 5899篇 |
2013年 | 5916篇 |
2012年 | 8546篇 |
2011年 | 8978篇 |
2010年 | 6226篇 |
2009年 | 5195篇 |
2008年 | 6322篇 |
2007年 | 6030篇 |
2006年 | 5595篇 |
2005年 | 4965篇 |
2004年 | 3815篇 |
2003年 | 3886篇 |
2002年 | 3413篇 |
2001年 | 2405篇 |
2000年 | 1864篇 |
1999年 | 1651篇 |
1998年 | 979篇 |
1997年 | 894篇 |
1996年 | 763篇 |
1995年 | 689篇 |
1994年 | 647篇 |
1993年 | 401篇 |
1992年 | 445篇 |
1991年 | 408篇 |
1990年 | 338篇 |
1989年 | 299篇 |
1988年 | 208篇 |
1987年 | 214篇 |
1986年 | 171篇 |
1985年 | 115篇 |
1984年 | 59篇 |
1983年 | 44篇 |
1982年 | 43篇 |
1981年 | 30篇 |
1980年 | 30篇 |
1979年 | 18篇 |
1978年 | 6篇 |
1975年 | 7篇 |
1973年 | 10篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
应用微血管灌注透明法观察研究5具成人周围神经干标本.重点观察神经自然分束部位微血管形态和分支分布规律.神经干内有非常完兽的血供系统.手术中循神经自然分束进行追踪分离,不会对神经血供产生明显影响.但在张力下牵拉缝合神经,将对神经干血供产生严重影响.神经束膜缝合比神经外膜缝合更强调在无张力下进行. 相似文献
103.
In this study we investigate the expression pattern of mucin genes in the human testis and evaluate the relationship between the expression of mucin genes and impaired spermatogenesis in the human testis. Thirty human testis tissues were collected from patients undergoing diagnostic testicular biopsy to investigate the cause of infertility. One part of the tissue underwent histological observation, and the other part of the tissue was subjected to semiquantitative RT-PCR of mucin genes, that is, mucin1, 2, 3, 4, and 9. The relative amount of mucin mRNAs was calculated by densitometry using glyceraldehydes-3-phosphate dehydrogenase (GAPDH) as an internal control. The samples were histologically diagnosed as either obstructive azoospermia with normal spermatogenesis (n = 13) or non-obstructive azoospermia with impaired spermatogenesis (n = 17). In the human testis with normal spermatogenesis, mRNA expression of mucin1, 9, 13 and GAPDH were found, but RT-PCR products of mucin 2, 3 and 4 were not detected. In the testis with impaired spermatogenesis, however, RT-PCR product of mucin1 was not found. There was no difference in the other mucin mRNA expression patterns between the testis with either normal or impaired spermatogenesis. To our knowledge, this study is the first that has detected the mRNA of mucin9 and 13 in human testis. This study also shows that mucin1 expression might be closely related to spermatogenesis. Our findings should be substantiated by more direct evidence, such as mucin protein expression and localization. 相似文献
104.
105.
作者曾报道豚鼠肠粘膜下神经丛内,可能有一种特殊类型的淋巴管旁神经元。为了对上述的研究提供进一步的证据,本文应用显示神经元特异性烯醇化酶(NSE)的免疫组织化学方法,对这种类型的神经元进行了观察。胃肠神经丛内所有的神经元都呈NSE阳性反应,小肠和结肠粘膜下丛内的淋巴管旁神经元,也显同样的阳性反应。平滑肌和结缔组织细胞均为阴性。大多数淋巴管旁神经元具有典型的神经元形态特征;有些细胞虽不具有明显的神经元形态特点,但它们都显相同的NSE阳性反应。本文为我们前文报道的淋巴管旁神经元提供了更可信的证据。 相似文献
106.
Jin H Kang Y Xiao C Zhu K Ma Y Xie Q Ma J Xie Q He C Yang Z Sun Z Zhang X Chen M Zhang F Wang B 《Viral immunology》2005,18(3):539-548
Prime-boost strategy has been exhibited its potency to enhance immune responses, which would be important to the success to develop a vaccine against the foot-and-mouth disease virus (FMDV). An eukaryotic expression construct encoding the FMDV capsid VP1 protein with a recombinant VP1 protein or a commercial FMDV vaccine were tested in the prime-boost strategy in mice and cattle trials. The levels of induced specific antibodies, T cell proliferations, and DTH activities were significantly higher in the prime-boost groups than in those vaccinated with DNA, protein or FMDV vaccine alone. More importantly, the levels of neutralizing antibodies in the former groups were significantly higher than others and could last for at least four months in cattle trials. This study suggests that the prime-boost strategy significantly improves the effective immunity and may provide a longer protection against FMDV infection. 相似文献
107.
Lei C Dongqing Z Yeqing S Oaks MK Lishan C Jianzhong J Jie Q Fang D Ningli L Xinghai H Daming R 《European journal of human genetics : EJHG》2005,13(7):823-828
Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is important for downregulation of T-cell activation, and CTLA-4 gene polymorphisms have been implicated as risk factors for rheumatoid arthritis (RA). Previous studies of the association between the +49 polymorphism of the CTLA-4 gene in RA have provided conflicting results. In order to determine association of the CTLA-4 gene with RA in Chinese Han population, we used denaturing gradient gel electrophoresis (DGGE) to genotype polymorphisms of four SNPs (MH30, +49, CT60 and JO31) of the CTLA-4 gene in 326 RA patients and 250 healthy controls. Furthermore, meta-analysis of all available studies relating +49 polymorphism to the risk of RA was performed to confirm the disease association. Among the SNPs examined, the genotype frequencies of CTLA-4 +49 and CT60 in RA patients differed significantly from controls (P=0.028 and 0.007). In addition, the distribution of four haplotypes constructed by these two SNPs was significantly different between patients and controls (chi(2)=10.58, d.f. =3, P=0.014). The meta-analysis also revealed that in both European and Asian populations, the CLTA-4 +49 G allele was associated with the risk of RA. These results suggested that the CTLA-4 gene might be involved in the susceptibility to RA in the Chinese Han population and both +49 and CT60 of CTLA-4 gene might be the causal variants in RA disease. 相似文献
108.
Joshua S. Newton Jin Li Zhi-Qiang Ning Diana E. Schoendorf John D. Norton John J. Murphy 《European journal of immunology》1996,26(4):811-816
B lymphocytes are activated following antigen stimulation of the B cell receptor but require co-stimulation with accessory molecules provided by interleukin (IL)-4/CD40 ligand for cell cycle progression and proliferation. By analyzing a panel of 11 early response genes induced by cross-linking of surface immunoglobulin, we show that CD40 signaling alone induces only 2 genes, c-myc together with an anonymous gene, 3L3, and that these are distinct from the set of genes induced in response to IL-4. Co-stimulation with the proliferative combination of anti-μ, IL-4 + CD40 signaling led to a fourfold enhancement of egr-2/krox20 expression over that seen with anti-μ alone. Egr-2 expression/activity was selectively inhibited by the immunosuppressive drug cyclosporin A, and antisense oligonucleotide blockade of Egr-2 activity elicited a dose-dependent inhibition of B cell proliferation. Taken together, these observations show that the early gene regulatory programs coupled to different surface receptors on B cells are largely distinct from each other, but that certain genes, exemplified by egr-2, may represent a point of convergence in the integration of different signaling pathways into the B cell proliferative response. 相似文献
109.
The intent of the present study was to use chemical or electrical stimulation of cerebellar afferents to determine how different stimulation paradigms affect the pattern of activation of different populations of neurons in the cerebellar cortex. Specifically, we analyzed immediate changes in neuronal activity, identified neurons affected by different stimulation paradigms, and determined the time course over which neuronal activity is altered. In the present study, we used either systemic (harmaline) or electrical stimulation of the inferior cerebellar peduncle (10 and 40 Hz) to alter the firing rate of climbing and mossy fiber afferents to the rat cerebellum and an antibody made against the proto-oncogene, c-fos, as a marker to identify activated neurons and glia. In control animals, only a few scattered granule cells express nuclear Fos-like immunoreactivity. Although no other cells show Fos-like immunoreactivity in their nuclei, Purkinje cells express Fos-like immunoreactivity within their somatic and dendritic cytoplasm in control animals. Within 15 min of chemical or electrical stimulation, numerous granule and glial cells express Fos-like immunoreactivity in their nuclei. Cells in the molecular layer express Fos-like immunoreactivity following harmaline stimulation in a time and lobule specific manner; they do not appear to be activated in the electrical stimulation paradigm. Following harmaline injections, there is an initial loss of Fos-like immunoreactivity in the cytoplasm of Purkinje cells; 90 min later, nuclear staining is observed in a few scattered Purkinje cells. Following electrical stimulation, the cytoplasmic staining in Purkinje cells is enhanced; it is never present in the nucleus. Data derived from this study reveal cell-specific temporal and spatial patterns of c-Fos activation that is unique to each paradigm. Further, it reveals the presence of an activity dependent protein in the cytoplasm of Purkinje cell somata and dendrites. 相似文献
110.
Kim SH Shin JW Park SA Kim YK Park MS Mok JM Yang WI Lee JW 《Journal of biomedical materials research. Part B, Applied biomaterials》2004,68(1):69-74
The purpose of this study is to determine the efficacy of bioactive calcium phosphate obtained from porcine cancellous bone for the treatment of bone defects and nonunion. Porcine cancellous bone blocks were heat treated at 1300 degrees C for 2 h. The chemical composition, calcium-to-phosphate ratio, and microstructure of the porcine bone blocks were examined. For in vivo implantation, bone defects were created on the anteromedial aspect of the proximal tibia in seven beagle dogs and the xenograft bone blocks were placed into these defects. Plain radiographs were taken at 2-week intervals for roentgenographic evaluation. At 12 weeks, the specimens were stained with hematoxylin and eosin (H&E). The composition and morphology of heat-treated porcine cancellous bone were found to be similar to heat-treated human cancellous bone. Radiographs showed union between the host bone/bone-block interfaces. At 12 weeks, uniform and substantial new bone formation was observed. It is concluded that heat-treated porcine cancellous bone demonstrated effective osteoconductivity. This high-temperature heat-treatment technique has several advantages, including decreased risk of disease transmission and immunoreactivity, while also offering excellent biocompatibility. 相似文献