全文获取类型
收费全文 | 6765篇 |
免费 | 275篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 65篇 |
儿科学 | 169篇 |
妇产科学 | 116篇 |
基础医学 | 743篇 |
口腔科学 | 129篇 |
临床医学 | 337篇 |
内科学 | 1529篇 |
皮肤病学 | 69篇 |
神经病学 | 661篇 |
特种医学 | 160篇 |
外科学 | 1196篇 |
综合类 | 26篇 |
预防医学 | 198篇 |
眼科学 | 214篇 |
药学 | 509篇 |
中国医学 | 19篇 |
肿瘤学 | 928篇 |
出版年
2023年 | 42篇 |
2022年 | 75篇 |
2021年 | 103篇 |
2020年 | 75篇 |
2019年 | 109篇 |
2018年 | 121篇 |
2017年 | 92篇 |
2016年 | 131篇 |
2015年 | 113篇 |
2014年 | 147篇 |
2013年 | 190篇 |
2012年 | 286篇 |
2011年 | 334篇 |
2010年 | 205篇 |
2009年 | 160篇 |
2008年 | 354篇 |
2007年 | 320篇 |
2006年 | 391篇 |
2005年 | 416篇 |
2004年 | 436篇 |
2003年 | 430篇 |
2002年 | 416篇 |
2001年 | 165篇 |
2000年 | 144篇 |
1999年 | 161篇 |
1998年 | 127篇 |
1997年 | 89篇 |
1996年 | 85篇 |
1995年 | 66篇 |
1994年 | 63篇 |
1993年 | 66篇 |
1992年 | 123篇 |
1991年 | 112篇 |
1990年 | 115篇 |
1989年 | 93篇 |
1988年 | 70篇 |
1987年 | 69篇 |
1986年 | 60篇 |
1985年 | 41篇 |
1984年 | 50篇 |
1983年 | 50篇 |
1982年 | 33篇 |
1981年 | 21篇 |
1980年 | 23篇 |
1979年 | 31篇 |
1977年 | 28篇 |
1976年 | 26篇 |
1975年 | 21篇 |
1973年 | 21篇 |
1972年 | 24篇 |
排序方式: 共有7068条查询结果,搜索用时 15 毫秒
51.
Interferon-{beta} inhibits bleomycin-induced lung fibrosis by decreasing transforming growth factor-{beta} and thrombospondin 总被引:2,自引:0,他引:2
Azuma A Li YJ Abe S Usuki J Matsuda K Henmi S Miyauchi Y Ueda K Izawa A Sone S Hashimoto S Kudoh S 《American journal of respiratory cell and molecular biology》2005,32(2):93-98
Pulmonary fibrosis is the result of abnormal processes of repair that occur after lung injury. Transforming growth factor (TGF)-beta is a key molecule in the progression of pulmonary fibrosis. Although clinical use of interferon (IFN)-beta did not improve survival in patients with idiopathic pulmonary fibrosis, because some preclinical studies have suggested that IFN-beta is a potent inhibitor of fibrogenesis, beneficial effects of IFN-beta have been expected. We therefore attempted to determine effects of IFN-beta and investigated the mechanism of action of IFN-beta in bleomycin-induced pulmonary fibrosis. Bleomycin at Day 0 and IFN-beta for 4 wk were administered intravenously to ICR mice. At 28 d after bleomycin injection, histologic and chemical analysis was performed for evaluation of effects of IFN-beta. Tissue distribution and amounts of TGF-beta1 and thrombospondin (TSP)-1/2 were analyzed. IFN-beta attenuated prolylhydroxylase activity, resulting in inhibition of pulmonary fibrosis. Bleomycin-induced increase in TGF-beta1 in epithelial cells and extracellular matrix was attenuated by IFN-beta. TSP-1/2 was limited in platelets of control mice, but was present in foamy cells in fibrotic regions induced by bleomycin. These findings suggest that the antifibrotic effect of IFN-beta is inhibition of TGF-beta and its activation via decrease in TSP-1/2 in lung tissue and change in location of TSP-1/2 from platelets to foamy cells. 相似文献
52.
A protein, Vp130, that interacts with the host cell wall was isolated from Chlorovirus CVK2. From its peptide sequence, the gene for Vp130 was identified on the PBCV-1 genomic sequence as an ORF combining A140R and A145R. In Vp130, the N-terminus was somehow modified and the C-terminus was occupied by 23-26 tandem repeats of a PAPK motif. In the internal region, Vp130 contained seven repeats of 70-73 amino acids, each copy of which was separated by PAPK sequences. This protein was well conserved among NC64A viruses. A recombinant rVp130N protein formed in Escherichia coli was shown not only to bind directly to the host cell wall in vitro but also to specifically bind to the host cells, as demonstrated by fluorescence microscopy. Because externally added rVp130N competed with CVK2 to bind to host cells, Vp130 is most likely to be a host-recognizing protein on the virion. 相似文献
53.
54.
Shoji M Kanai M Matsubara E Tomidokoro Y Shizuka M Ikeda Y Ikeda M Harigaya Y Okamoto K Hirai S 《Neurobiology of aging》2001,22(2):209-215
Decreased levels of cerebrospinal fluid (CSF) Abeta42 is a diagnostic marker of Alzheimer's disease. To clarify the biological basis of this marker, the physiological alterations of CSF Abeta40 and Abeta42 by aging were studied. CSF samples from 92 normal subjects between 8 and 89 years old were measured using a specific ELISA for Abeta40 and Abeta42(43). High concentrations of Abeta40 and Abeta42(43) in the young group, under 29 years old, changed to be at low concentrations in the adult group between 30 and 59 years old. Subsequently, the levels increased again with age. Third order regression analysis showed a significant correlation between the levels of Abeta40 and age (Y = - 169 X(3) + 3.1X(2)- 0.02X + 4135; P < 0.034) and between the levels of Abeta42(43) and age (Y = - 46 X(3) + 0.9 X(2)- 0.005X + 992; P < 0.005). The levels of CSF Abeta40 and Abeta42(43) were physiologically regulated to show a U-shaped natural course in normal aging. These findings suggested that the physiological increase of Abeta42(43) over 59 years of age is selectively inhibited in Alzheimer's disease. 相似文献
55.
Transmission electron microscopy of thin sections of the rat incisor pulp revealed that in the middle region of the incisor there were fenestrated capillaries in the “predentinal plexus” and that this region contained the tallest odontoblasts. The odontoblasts gradually became shortened in the incisal part of this region: the fenestrated capillaries in the predentinal plexus changed to continuous type capillaries. Almost all the odontoblasts had degenerated near the incisal end of the tooth. The predentinal plexus disappeared in this region, but the “subodontoblastic capillary plexus” persisted. In a specific region just beneath the worn incisal end, numerous macrophages and polymorphonuclear neutrophils appeared and scavenged the degenerating cells, possibly including the odontoblasts. © 1993 Wiley-Liss, Inc. 相似文献
56.
Yasuo Harigaya Yasushi Tomidokoro Masaki Ikeda Atsushi Sasaki Takeshi Kawarabayashi Etsuro Matsubara Mitsuyasu Kanai Takaomi C. Saido Steven G. Younkin Mikio Shoji 《Neuroscience letters》2006
To clarify how Aβ deposits start in the brain, we examined the early to late stages of senile plaques and amyloid angiopathy in APPsw mice. All types of human senile plaques were observed in the mouse brains. The premature forms of cored plaques appeared first in the cerebral cortex of mice at 7–8 months old. Then, amyloid angiopathy emerged, followed by diffuse plaques consisting of Aβ1–42. Modifications of the N-terminus of Aβ were late phase phenomena. The premature forms of cored plaques were composed of central Aβ1–40 amyloid cores, surrounding amorphous Aβ1–42 deposits, and accumulation of Aβ1–42 in some peripheral cells. These cells were incorporated in amyloid cores, and these plaques developed to large cored plaques composed of Aβ1–40 and Aβ1–42. The size and number of cored plaques were increased with age. These findings indicate different evolution paths for cored plaques and diffuse plaques, and suggest the presence of a pathway that initiates with the intracellular accumulation of Aβ1–42 and leads to the development of classic plaques in human brain tissues. 相似文献
57.
Ohyashiki JH Suzuki A Aritaki K Nagate A Shoji N Ohyashiki K Ojima T Abe K Yamamoto K 《International journal of molecular medicine》2000,6(4):427-432
Reactivation of human herpesvirus 6 (HHV-6) is common following allogeneic marrow transplantation, however, little is known about the immune control and pathogenic potential of HHV-6 infection after transplantation. In order to determine whether reactivation of HHV-6 plays an important role in the development of complications in patients undergoing allogeneic bone marrow transplantation or not, we developed a very rapid quantification of viral DNA using a LightCycler. The amount of viral DNA was determined using a supernatant of a chronically infected cell line [TaY(OK)] which contains a known amount of viral DNA. Peripheral blood cells were collected from 5 patients undergoing allogeneic bone marrow transplantation once before transplant and once per week after transplant for 8-24 weeks. The real-time PCR system revealed that there was a linear correlation in the range of 101 to 105 molecules of reference. Using this system, we have found the presence of non-diagnosed HHV-6 reactivation as well as symptomatic infection, indicating the potential for routine implementation of this technology for laboratory diagnosis of HHV-6 infection. Our study shows that this method of rapid quantification of HHV-6 genomes by the real-time PCR using a LightCycler may be useful not only to understand the reconstitution of the immune system following marrow transplantation but also to manage the care of patients. 相似文献
58.
Immunoreactive highly polysialylated neural cell adhesion molecule (PSA-NCAM) expression was examined in the rat with repeated exposure to amygdaloid kindled generalized seizures (GS). In the sham control brain, PSA-NCAM staining was slightly observed in the subventricular zone (SVZ) of the striatum. The number of PSA-NCAM positive cells increased four times in the bilateral SVZ after three consecutive GS, with a further increase after 30 consecutive GS. As PSA-NCAM is involved in neural plasticity as well as migration of neural stem cells (NSC), expression of PSA-NCAM in the SVZ suggests that the recurrent GS may mainly contribute to reconstruction of synaptic network and could also contribute to NSC migration after kindling. 相似文献
59.
Reiji Haba Shoji Kobayashi Hiroshi Miki Eiichiro Hirakawa Kousuke Saoo Takayuki Iwai Seiji Mori Masaki Ohmori 《Pathology international》1993,43(12):774-778
A case of polymorphous low-grade adenocarcinoma (PLGA) in the submandibular gland is reported. A 72 year old woman presented with a 5 year history of a gradually expanding tumor in the submandibular region. The surgical specimen revealed a relatively well demarcated tumor, 35 × 35 × 20 mm in size. Macroscopically, necrosis and hemorrhage were not seen in the solid tumor. Histologically, the tumor growth pattern was variable, composed of tubular, papillary, solid, trabecular and cribriform structures. Immunohistochemically, some tumor cells were positive for epithelial membrane antigen (EMA), S-100 protein, keratin, and carcino-embryonic antigen (CEA). Electron microscopically, prominent microvilli projected into the luminal spaces, and basal lamina and hemidesmosomes were seen in the tumor cells adjacent to the connective tissues. The submandibular gland is an extremely rare location for PLGA. To the authors' knowledge, this is the first case of its kind reported in the English literature. 相似文献
60.