全文获取类型
收费全文 | 41296篇 |
免费 | 1945篇 |
国内免费 | 170篇 |
专业分类
耳鼻咽喉 | 551篇 |
儿科学 | 761篇 |
妇产科学 | 443篇 |
基础医学 | 4973篇 |
口腔科学 | 1251篇 |
临床医学 | 2847篇 |
内科学 | 9542篇 |
皮肤病学 | 896篇 |
神经病学 | 3814篇 |
特种医学 | 2048篇 |
外国民族医学 | 1篇 |
外科学 | 6621篇 |
综合类 | 158篇 |
一般理论 | 6篇 |
预防医学 | 1215篇 |
眼科学 | 837篇 |
药学 | 2652篇 |
中国医学 | 75篇 |
肿瘤学 | 4720篇 |
出版年
2023年 | 226篇 |
2022年 | 395篇 |
2021年 | 708篇 |
2020年 | 406篇 |
2019年 | 543篇 |
2018年 | 706篇 |
2017年 | 578篇 |
2016年 | 747篇 |
2015年 | 720篇 |
2014年 | 951篇 |
2013年 | 1174篇 |
2012年 | 1952篇 |
2011年 | 1990篇 |
2010年 | 1211篇 |
2009年 | 1031篇 |
2008年 | 1788篇 |
2007年 | 2012篇 |
2006年 | 1908篇 |
2005年 | 1896篇 |
2004年 | 1910篇 |
2003年 | 1798篇 |
2002年 | 1844篇 |
2001年 | 1365篇 |
2000年 | 1457篇 |
1999年 | 1333篇 |
1998年 | 565篇 |
1997年 | 465篇 |
1996年 | 445篇 |
1995年 | 363篇 |
1994年 | 385篇 |
1993年 | 320篇 |
1992年 | 1018篇 |
1991年 | 876篇 |
1990年 | 856篇 |
1989年 | 833篇 |
1988年 | 787篇 |
1987年 | 774篇 |
1986年 | 681篇 |
1985年 | 631篇 |
1984年 | 444篇 |
1983年 | 353篇 |
1982年 | 158篇 |
1979年 | 298篇 |
1978年 | 207篇 |
1977年 | 184篇 |
1974年 | 189篇 |
1973年 | 163篇 |
1972年 | 164篇 |
1971年 | 183篇 |
1969年 | 178篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
We studied functional and immunohistochemical characteristics of cultured rat microglia. Unstimulated microglia did not proliferate. Microglia stimulated with LCM (L929 conditioned medium: colony stimulating factor-1) had proliferative activity and increased acid phosphatase activity. LPS (lipopolysaccharide) and IFN gamma (interferon-gamma) but did not affect proliferative activity. Immunohistochemically, RCA-1 lectin and GS-1 lectin, which react to beta-D-galactose and alpha-D-galactose respectively, strongly reacted to the cytoplasm and membrane of unstimulated microglia. After stimulation with LCM, microglia elongated processes and decreased response to these lectins. On the other hand, microglia stimulated with LCM showed increased reactivity to monoclonal antibody of vimentin. Microglia stimulated with LPS had round shape and had response to these lectins and vimentin. Microglia stimulated with IFN gamma had adhesive activity and weakly stained with these lectins but not with vimentin. ED-1 (monoclonal antibody of rat monocytes/macrophages) reacted to unstimulated and stimulated microglia. In flow cytometry, unstimulated microglia expressed OX-18 (MHC class I) and W3/25 (CD4) antigen. After stimulation with IFN gamma, microglia were induced to express these antigens. CD4 antigen is a marker of helper/inducer T cells and thought to be a receptor of HIV. The results that microglia had CD4 antigen which was further induced with IFN gamma are important to investigate infection of the CNS with HIV. OX-6 (Ia) antigen was induced with IFN gamma. This indicates that the microglia plays a central role in the CNS immune reaction. These characteristics of cultured rat microglia provide useful informations to investigate the pathogenesis of the CNS disorders. 相似文献
13.
14.
15.
Milena Soares Santos Guilherme de Sousa Ribeiro Tainara Queiroz Oliveira Renan Cardoso Nery Santos Edilane Gouveia Kátia Salgado Daniele Takahashi Cleuber Fontes Leila Carvalho Campos Mitermayer Galvão Reis Albert Icksang Ko Joice Neves Reis 《International journal of infectious diseases》2009,13(4):456-461
16.
Takayoshi Owada Kentaro Takahashi Yasuhiko Kita 《Modern rheumatology / the Japan Rheumatism Association》2009,19(5):573-580
We report 51- and 43-year-old Japanese female patients with systemic lupus erythematosus (SLE) associated with subarachnoid
hemorrhage (SAH) due to rupture of intracranial saccular aneurysms. We also review the literature of Japanese SLE patients
with SAH. SAH in Japanese SLE patients is more frequent than in patients from Western countries, has different features from
the general population, and can occur regardless of SLE disease activity. Clinicians must pay attention to SAH in all SLE
patients. 相似文献
17.
Yuji Masuda Toyonobu Yamashita Tetsuji Hirao Motoji Takahashi 《Skin research and technology》2009,15(2):224-229
Background/purpose: It is crucial to establish an accurate method for measuring skin pigmentation in cosmetic science and clinical dermatology. Here, we report a non-invasive precise method for measuring skin melanin content.
Methods: In order to determine the concentrations of melanin and hemoglobin in skin, we used the spectrum resolution (SR) method. In brief, the absorption spectrum of the skin was calculated from the reflection spectrum using a spectrophotometer. The concentrations of melanin and hemoglobin were then determined using a multiple regression analysis, assuming that the absorption spectrum of the skin is expressed as a linear summation of the absorptions of melanin and hemoglobin according to the Lambert–Beer law. The skin changes in the volar forearm, which had been irradiated by ultraviolet rays (UV), were observed daily by the SR method.
Results: A multiple regression analysis with an absorption spectrum of 500–700 nm was performed. The multiple correlation coefficient was 0.993, resulting in a satisfactory precise estimate of the concentrations of melanin. After UV irradiation, the concentration of melanin monitored by the SR method increased until 8 days and decreased gradually afterwards.
Conclusions: The SR method allows the evaluation of the changes of epidermal melanin induced by UV irradiation. 相似文献
Methods: In order to determine the concentrations of melanin and hemoglobin in skin, we used the spectrum resolution (SR) method. In brief, the absorption spectrum of the skin was calculated from the reflection spectrum using a spectrophotometer. The concentrations of melanin and hemoglobin were then determined using a multiple regression analysis, assuming that the absorption spectrum of the skin is expressed as a linear summation of the absorptions of melanin and hemoglobin according to the Lambert–Beer law. The skin changes in the volar forearm, which had been irradiated by ultraviolet rays (UV), were observed daily by the SR method.
Results: A multiple regression analysis with an absorption spectrum of 500–700 nm was performed. The multiple correlation coefficient was 0.993, resulting in a satisfactory precise estimate of the concentrations of melanin. After UV irradiation, the concentration of melanin monitored by the SR method increased until 8 days and decreased gradually afterwards.
Conclusions: The SR method allows the evaluation of the changes of epidermal melanin induced by UV irradiation. 相似文献
18.
H. Kurokawa M. Zhang S. Matsumoto Y. Yamashita T. Tomoyose T. Tanaka H. Fukuyama T. Takahashi 《Journal of oral pathology & medicine》2005,34(6):329-333
BACKGROUND: Although many histopathologic factors in squamous cell carcinoma of the tongue predict the prognosis, the major predictive factors have not been identified clearly. This study analyzed the prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma. METHODS: The clinicopathologic features of 124 consecutive patients seen between January 1985 and December 1999 with previously untreated squamous cell carcinoma of the tongue were reviewed. Their mean age was 58.5 years (range: 23-90) and the male-female ratio was 1.8: 1 (79 men and 45 women). There were 41, 40, 30, and 13 cases at stage I to stage IV, respectively. The clinicopathologic factors, especially the histologic grade at the deep invasive front (invasive front grade, IFG), were analyzed to determine factors predicting prognosis. RESULTS: The 5-year disease-free survival rate of the patients treated with curative aim only was 66.7%. Clinicopathologic factors significantly associated with the prognosis were T classification, tumor size, stage classification, tumor depth, macroscopic appearance, cervical lymph node metastasis (nodal metastasis), microvascular invasion, and IFG. In a multivariate analysis, patients with tumor depth >/=4 mm, IFG >/=8 points, and nodal metastasis had a reduced disease-free survival and IFG >/=11 points had a predictive value for nodal metastasis (odds ratio: 7.34; P = 0.0019). CONCLUSION: This study found that a high IFG malignancy score had a high prognostic value for squamous cell carcinoma of the tongue. 相似文献
19.
M Shibata T Ohkubo H Takahashi T Kudo R Inoki 《Nihon yakurigaku zasshi. Folia pharmacologica Japonica》1986,88(2):101-107
Opiates and opioid peptides were administered in the order of 10(-9)-10(-6) mol peripherally, and their action on pain sensitivity was investigated by the modified formalin test which has two characteristic pain responses (the first and the second phase) in the mouse hindpaw. Opioid peptides (20-500 pmol) had dose-dependent analgesia against both first and second phases, and their action ranked dynorphin greater than [D-Ala2, Met5]-enkephalinamide greater than [Met5]-enkephalin. EKC and morphine (0.4-2.5 nmol) inhibited pain response of the first phase, but produced hyperalgesia in the second phase dose-dependently. Lidocaine hydrochloride had peripheral analgesic action, but was about 500-10000 times weaker than these substances. So, these peripheral analgesic actions have a different mechanism from that of local anesthetic action. N-methyl levallorphan which is thought to be a peripherally selective narcotic antagonist reversed these peripheral analgesic actions at the first and second phases and also prevented the hyperalgesic effects of EKC and morphine at the second phase. Naloxone reversed analgesia at only the first phase. These results suggest that an analgesic mechanism by opioids may exist at the peripheral site as well. Furthermore, it is estimated that a receptor exists which is antagonized by N-methyl levallorphan but not by naloxone and that there is a system of hyperalgesia by EKC and morphine in pain modulation. 相似文献