全文获取类型
收费全文 | 7154篇 |
免费 | 293篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 63篇 |
儿科学 | 180篇 |
妇产科学 | 111篇 |
基础医学 | 792篇 |
口腔科学 | 111篇 |
临床医学 | 364篇 |
内科学 | 1625篇 |
皮肤病学 | 82篇 |
神经病学 | 693篇 |
特种医学 | 181篇 |
外科学 | 1234篇 |
综合类 | 28篇 |
预防医学 | 202篇 |
眼科学 | 228篇 |
药学 | 511篇 |
中国医学 | 19篇 |
肿瘤学 | 1058篇 |
出版年
2023年 | 39篇 |
2022年 | 66篇 |
2021年 | 100篇 |
2020年 | 70篇 |
2019年 | 110篇 |
2018年 | 119篇 |
2017年 | 91篇 |
2016年 | 130篇 |
2015年 | 114篇 |
2014年 | 148篇 |
2013年 | 190篇 |
2012年 | 291篇 |
2011年 | 336篇 |
2010年 | 215篇 |
2009年 | 163篇 |
2008年 | 367篇 |
2007年 | 344篇 |
2006年 | 416篇 |
2005年 | 434篇 |
2004年 | 449篇 |
2003年 | 455篇 |
2002年 | 446篇 |
2001年 | 192篇 |
2000年 | 201篇 |
1999年 | 204篇 |
1998年 | 141篇 |
1997年 | 105篇 |
1996年 | 94篇 |
1995年 | 83篇 |
1994年 | 66篇 |
1993年 | 73篇 |
1992年 | 140篇 |
1991年 | 123篇 |
1990年 | 123篇 |
1989年 | 91篇 |
1988年 | 86篇 |
1987年 | 74篇 |
1986年 | 65篇 |
1985年 | 51篇 |
1984年 | 49篇 |
1983年 | 46篇 |
1982年 | 37篇 |
1981年 | 24篇 |
1980年 | 23篇 |
1979年 | 37篇 |
1978年 | 23篇 |
1977年 | 28篇 |
1976年 | 25篇 |
1975年 | 20篇 |
1972年 | 22篇 |
排序方式: 共有7482条查询结果,搜索用时 312 毫秒
51.
Reiji Haba Shoji Kobayashi Eiichiro Hlrakawa Hiroshi Miki Takeshi Okino Tatsuo Kurokawa Syuu Yamamoto 《Pathology international》1996,46(7):515-519
An extremely rare case of malignant fibrous histiocytoma In the pancreas Is reported. A 70-year-old man complained of upper abdominal discomfort. A tumor in the head of the pancreas was demonstrated by ultrasonography and computed tomography. The surgical specimen revealed a relatively well demarcated tumor, 9 × 7 × 6.5cm in size. Microscopically, fibroblastic, histiocytic, and muitinucleated giant tumor cells were observed in the myxoid area, but some tumor cells had proliferated in a storiform-pleomorphlc pattern. Immunohtstochemically, some tumor cells were positive for lysozyme, α-1-antitrypsin, α-1-antichymotrypsin, and vimentin. Electron microscopically, tumor cells showed a combination of fibroblastic and histiocytic features. The patient Is currently well with no evidence of recurrence or metastasis 22 months after operation. 相似文献
52.
Sakurai Y Shoji M Matsubara T Imazu H Hasegawa S Ochiai M Funabiki T Mizoguchi Y Kuroda M Kasahara M 《Pathology international》2000,50(8):655-659
Angiomyomatous hamartoma is a rare disease with a predisposition for the inguinal lymph nodes. A 51-year-old male patient visited a local hospital because of a right inguinal mass, measuring 3 x 4 cm in size, which was resected. The resected specimen showed irregularly distributed thick-walled vessels in the hilum, extending into the medulla and focally into the cortex of the node, eventually becoming more dispersed and associated with smooth muscle cells splaying into sclerotic stroma. These findings are compatible with an angiomyomatous hamartoma. Another tumor-like mass appeared shortly after the resection at the same location, but was not an angiomyomatous hamartoma, rather it was composed of edematous stromal tissue with proliferating smooth muscle cells. The stromal component included thick-walled blood vessels and lymphatics. Although it could not be determined whether these associated changes in the surrounding stroma are a cause or an effect of angiomyomatous hamartoma, they indicate the clinical difficulty in determining an appropriate area of resection and may provide clues to the pathogenesis of angiomyomatous hamartoma. 相似文献
53.
Effect of ethanol treatment on metabolic activation and detoxification of esophagus carcinogenic N-nitrosamines in rat liver 总被引:3,自引:0,他引:3
In order to elucidate the mechanism underlying enhancement by ethanol of N-nitrosodiethylamine (DEN)- and N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumorigenesis in rats, hepatic levels of cytochrome P-450 (CYP) enzymes, mutagenic activation of several N-nitrosamines and three kinds of UDP-glucuronyltransferase (UDPGT) activities were assayed in F344 rats. Immunoblot analyses of microsomal CYP proteins revealed induction of CYP2E1 (approximately 2-fold), but not CYP2B1/2, 1A1/2 or 3A2, by treatment with 10% ethanol in the drinking water for 2 weeks. In contrast, s.c. treatment with 0.5 mg/kg NMBA three times per week for 2 weeks produced no significant alterations in the levels of these CYP species. Ethanol treatment also elevated the mutagenic activities of N-nitrosodimethylamine (DMN), DEN and N-nitrosopyrrolidine (NPYR) in strain TA100 up to 2.1-, 1.6- and 2.3-fold above each control, respectively. However, this was not the cases for four N-nitrosamines, including NMBA, in strain TA100 and two heterocyclic amines and aflatoxin B(1) in strain TA98. In addition, ethanol did not affect UDPGT activities towards 4-nitrophenol, bilirubin and testosterone. Hepatic CYP species responsible for mutagenic activation of selected N-nitrosodialkylamines were confirmed by use of specific CYP inducers and inhibitors with the liver from F344 and Wistar rats, indicating that DMN, DEN and NMBA are selectively activated by CYP2E1, predominantly by CYP2E1 with a slight contribution by CYP2B2 and selectively by CYP2B1/2, respectively. These results demonstrate that ethanol exerts an enhancing effect on mutagenic activation by CYP2E1 of DMN, DEN and NPYR, but does not affect that of NMBA and the other carcinogens by CYP2B1/2, 1A1/2 and 3A2 and UDPGT1A1, 1A6 and 2B1 activities. Consequently, this suggests that enhancement by ethanol of DEN-induced esophageal carcinogenesis in F344 rats can be attributed to an increase in hepatic activation during the initiation phase, but that of NMBA-induced tumorigenesis is not attributable to metabolic activation and inactivation via glucuronidation in liver. 相似文献
54.
Masayuki Nakayama Masashi Bando Tatsuya Hosono Hideaki Yamasawa Shoji Ohno Yukihiko Sugiyama 《Arerugī》2007,56(11):1384-1389
BACKGROUND: Our aim is to evaluate the significance of DLST by Shosaikoto. METHODS: We clinically evaluated 3 cases of drug-induced pneumonia assumed to be caused by Shosaikoto, and we performed DLST of Shosaikoto for healthy controls, and compared the data with drug-induced pneumonia cases of Shosaikoto. RESULTS: As clinical characteristics of 3 cases, 2 cases were positive for hepatitis C virus antibody, and 1 case was positive for DLST of Shosaikoto. The observed chest high-resolution CT (HRCT) findings showed hypersensitivity pneumonia (HP) pattern in all 3 cases. Prognosis was good in all 3 cases. DLST of Shosaikoto was positive in 27.5% of healthy controls. Stimulation index (S.I.) of DLST in drug-induced pneumonia cases increased depending on drug dilution density, compared to that of healthy controls. CONCLUSION: DLST of Shosaikoto showed high false-positive rate. However, we may be able to distinguish the true-positive cases with the false-positive cases by comparing the S.I. of DLST according to drug dilution density. 相似文献
55.
Fumitaka Saji Yoshihiro Tokugawa Shoji Kamiura Yoshihiro Samejima Kazutomo Ohashi Chihiro Azuma Osamu Tanizawa 《Journal of clinical immunology》1989,9(5):409-414
The seroprevalence rate of human T-cell leukemia virus type I (HTLV-I) in pregnant women in the Osaka district was determined by enzyme-linked immunosorbent assay and Western blot analysis. Twenty-one (1.0%) of 2192 samples tested were positive for both assays and the seropositive parturients were found to be integrated with HTLV-I proviral DNA in their mononuclear cells by a DNA dot blot hybridization assay using HTLV-I DNA probe or by a selective DNA amplification technique using the polymerase chain reaction (PCR). On the other hand, proviral DNA was not detected in cord blood of the neonates born to the carrier mothers, indicating that transplacental infection of HTLV-I during pregnancy could be excluded. The results support the hypothesis that postpartum infection via breast milk plays a significant role among the possible perinatal transmission routes. 相似文献
56.
Salahuddin Saira; Ookutsu Shoji; Goto Kazufumi; Nakanishi Yoshihiko; Nagata Yukihiro 《Human reproduction (Oxford, England)》1995,10(9):2382-2385
We have evaluated the effects of embryo density and the co-cultureof unfertilized (degenerating) oocytes on the development ofin-vitro fertilized (IVF) mouse embryos. In experiment 1, groupsof one, five, 10 or 20 zygotes were cultured in 20 µldrops of modified human tubal fluid (HTF) medium for 168 h at38.7°C in 5% CO2 and 95% air. As the embryo density increased,significantly (P < 0.05) higher rates of embryos reachedhatched blastocyst stage. In addition, the time required forhatching after IVF was significantly (P < 0.05) shortenedby the increase in embryo density. In experiment 2, 10 IVF zygoteswere cultured with or without 10 unfertilized (degenerating)oocytes in 20 µl drops of HTF medium. The rates of IVFembryos that developed to morula, blastocyst, expanded blastocystand hatched blastocyst stages were decreased significantly (P< 0.01) by culturing embryos with unfertilized oocytes comparedwith culturing embryos alone. In experiment 3, groups of oneor 10 IVF zygotes or 10 IVF zygotes plus 10 unfertilized oocyteswere cultured in 20 µl drops of HTF medium and the numberof cells per blastocyst was examined at 120 h after IVF. Increasingembryo density resulted in a significant (P < 0.05) increasein the number of cells per blastocyst. In contrast, the cellnumber of IVF embryos that developed to blastocyst decreasedsignificantly (P < 0.05) when they were cultured with unfertilizedoocytes. The results suggest that in-vitro development of IVFmouse embryos is enhanced by increasing embryo density and isimpaired by co-culture with unfertilized (degenerating) oocytes. 相似文献
57.
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
58.
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
59.
60.
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