全文获取类型
收费全文 | 5027篇 |
免费 | 269篇 |
国内免费 | 36篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 150篇 |
妇产科学 | 62篇 |
基础医学 | 650篇 |
口腔科学 | 123篇 |
临床医学 | 381篇 |
内科学 | 1284篇 |
皮肤病学 | 166篇 |
神经病学 | 495篇 |
特种医学 | 160篇 |
外科学 | 603篇 |
综合类 | 28篇 |
预防医学 | 149篇 |
眼科学 | 84篇 |
药学 | 412篇 |
中国医学 | 33篇 |
肿瘤学 | 512篇 |
出版年
2023年 | 35篇 |
2022年 | 38篇 |
2021年 | 99篇 |
2020年 | 76篇 |
2019年 | 87篇 |
2018年 | 112篇 |
2017年 | 82篇 |
2016年 | 97篇 |
2015年 | 98篇 |
2014年 | 160篇 |
2013年 | 193篇 |
2012年 | 279篇 |
2011年 | 310篇 |
2010年 | 180篇 |
2009年 | 163篇 |
2008年 | 264篇 |
2007年 | 295篇 |
2006年 | 256篇 |
2005年 | 300篇 |
2004年 | 241篇 |
2003年 | 250篇 |
2002年 | 257篇 |
2001年 | 146篇 |
2000年 | 109篇 |
1999年 | 115篇 |
1998年 | 55篇 |
1997年 | 48篇 |
1996年 | 45篇 |
1995年 | 34篇 |
1994年 | 22篇 |
1993年 | 26篇 |
1992年 | 79篇 |
1991年 | 65篇 |
1990年 | 80篇 |
1989年 | 79篇 |
1988年 | 64篇 |
1987年 | 52篇 |
1986年 | 39篇 |
1985年 | 55篇 |
1984年 | 38篇 |
1983年 | 30篇 |
1981年 | 17篇 |
1980年 | 21篇 |
1979年 | 29篇 |
1978年 | 26篇 |
1977年 | 16篇 |
1974年 | 22篇 |
1973年 | 15篇 |
1970年 | 20篇 |
1967年 | 13篇 |
排序方式: 共有5332条查询结果,搜索用时 15 毫秒
41.
An immunohistochemical analysis of the cat central nervous system revealed that a monoclonal antibody which recognizes a soluble cytosolic protein, R2D5, bound two regions in a prominent spatial gradient. In the medial and lateral superior olivary nuclei of the brainstem, R2D5 immunoreactivity appeared as a gradient across a population of topographically ordered principal neurons. The spatial gradient corresponded to the tonotopic organization in the superior olivary nuclei: i.e., R2D5 immunoreactivity tended to occur more frequently and intensely in low-frequency neurons than in high-frequency neurons. Granule cells in the hippocampal dentate gyrus also had a pronounced spatial gradient in R2D5 immunoreactivity expression, and this gradient corresponded to the septotemporal axis of the hippocampus. Granule cells of the temporal (ventral) portions of the hippocampus were labeled intensely with R2D5 antibody, while those located in progressively more septal (dorsal) portions had gradually less immunoreactivity. These results suggest that in both the superior olivary nuclei and the hippocampal dentate gyrus, neurons differ in intrinsic properties by their position along specific axes. They suggest also that the hippocampus has an intrinsic functional organization related to the spatial gradient along its septotemporal axis. 相似文献
42.
In its pure form, mucinous breast carcinoma (MC) has a much better prognosis than infiltrating ductal carcinoma (IDC). Mixed MC-IDC has the prognosis of IDC. We compared the fine-needle aspiration (FNA) cytology and histology of nine cases of pure MC with 13 cases of mixed MC-IDC. While typical of pure MC, abundant mucin (3+/3+) was noted in smears from three cases of mixed tumor and is thus necessary but not sufficient for a diagnosis of pure MC. Cellular pleomorphism has been said not to be a feature of MC; however, we found occasional large cells markedly different from the typical small uniform cells of MC in four pure and seven mixed tumors. Cytologic features indicative of a mixed tumor include one or more smears totally without mucin, scantly amounts of mucin, or necrosis. A combination of features indicative of pure mucinous carcinoma in FNA included abundant mucin on all smears, no pleomorphism, and no necrosis. Many cases will have smear patterns that are not typical of either profile and should probably be designated as carcinoma with a mucinous component. 相似文献
43.
Characterization of pseudotype VSV possessing HCV envelope proteins 总被引:18,自引:0,他引:18
Matsuura Y Tani H Suzuki K Kimura-Someya T Suzuki R Aizaki H Ishii K Moriishi K Robison CS Whitt MA Miyamura T 《Virology》2001,286(2):263-275
The genome of hepatitis C virus (HCV) encodes two envelope glycoproteins (E1 and E2), which are thought to be responsible for receptor binding and membrane fusion resulting in virus penetration. To investigate cell surface determinants important for HCV infection, we used a recombinant vesicular stomatitis virus (VSV) in which the glycoprotein gene was replaced with a reporter gene encoding green fluorescent protein (GFP) and produced HCV-VSV pseudotypes possessing chimeric HCV E1 or E2 glycoproteins, either individually or together. The infectivity of the pseudotypes was determined by quantifying the number of cells expressing the GFP reporter gene. Pseudotypes that contained both of the chimeric E1 and E2 proteins exhibited 10--20 times higher infectivity on HepG2 cells than the viruses possessing either of the glycoproteins individually. These results indicated that both E1 and E2 envelope proteins are required for maximal infection by HCV. The infectivity of the pseudotype virus was not neutralized by anti-VSV polyclonal antibodies. Bovine lactoferrin specifically inhibited the infection of the pseudotype virus. Treatment of HepG2 cells with Pronase, heparinase, and heparitinase but not with phospholipase C and sodium periodate reduced the infectivity. Therefore, cell surface proteins and some glycosaminoglycans play an important role in binding or entry of HCV into susceptible cells. The pseudotype VSV possessing the chimeric HCV glycoproteins might offer an efficient tool for future research on cellular receptors for HCV and for the development of prophylactics and therapeutics for hepatitis C. 相似文献
44.
Experimental autoimmune thyroiditis in nonobese diabetic mice lacking interferon regulatory factor-1
Jin Z Mori K Fujimori K Hoshikawa S Tani J Satoh J Ito S Satomi S Yoshida K 《Clinical immunology (Orlando, Fla.)》2004,113(2):187-192
Interferon regulatory factor-1 (IRF-1) is pivotal in the regulation of interferon (IFN)-mediated immune reactions, and studies suggest that IRF-1 is involved in the development of autoimmune diseases. IRF-1+/+, +/-, and -/- nonobese diabetic (NOD) mice were immunized with mouse thyroglobulin (mTg) to determine whether IRF-1 is required in experimental autoimmune thyroiditis (EAT), a murine model for Hashimoto's thyroiditis (HT). IRF-1-deficient mice developed EAT and anti-mTg antibodies comparable to IRF-1+/+ and +/- mice. Whereas both CD4+ and CD8+ T cells were found in thyroids of IRF-1+/+ mice, the latter was not in IRF-1-/- mice. Major histocompatibility complex class II antigen was comparably expressed in thyroids of IRF-1+/+ and -/- mice. Lack of IRF-1 resulted in decreased CD8+ T cell number in the spleen and reduced IFNgamma production by splenocytes. Our results suggest that IRF-1 is not pivotal in EAT in NOD mice. 相似文献
45.
Zusammenfassung Ein 2 1/2 Stunden lang bei 45o erhitzter, nicht vollständig abgetöteter Pneumokokkenimpfstoff hatte schlechte immunisierende Wirkung.Ein anderer Pneumokokkenimpfstoff, der ebenfalls 2 1/2 Stunden auf 45o erhitzt, dabei aber vollständig abgetötet und dann nachträglich noch 1/2 Stunde auf 56o erhitzt war, war von guter Schutzwirkung.Hiernach sind durch schonende Abtötung bei niedrigen Temperaturen gewonnene Pneumokokken-Impfstoffe zum mindesten in ihrer Wirkung unzuverlässig und daher für die Praxis zu widerraten.Bei 100o 10 Minuten bis 4 Stunden lang erhitzte Pneumokokken stets einen guten Impfstoff.14 Tage lang täglich 1 Stunde auf 100o erhitzte Pneumokokken ergaben nur schlechte immunisierende Wirkung.Bei längerer Züchtung typischer Pneumokokkenstämme bei 39o wurden verschiedenartige Veränderungen beobachtet, darunter Virulenzabschwächung. Derart avirulente Pneumokokken ergaben auch lebend meist schlechten Immunisierungserfold, doch kommen Ausnahmen vor.Ein solcher vollkommen avirulenter, aber noch gallelöslicher Pneumokokkus wirkte sowohl lebend als auch nach Abtötung bei 100o gut antigen. 相似文献
46.
47.
Makiko Itami Toshinao Takenouchi Junichi Tamaru Kenichi Harigaya Atsuo Mikata 《Pathology international》1991,41(4):277-285
It is well known that non Hodgkin's lymphoma (NHL) cells express various antigens which are normally involved in a variety of functions. In addition, NHL is diverse in its proliferative capacity. To investigate the relation between these factors and the clinical picture, 45 cases of NHL were studied by immunohistochemistry using snap-frozen materials obtained before therapy. Reactivities with 27 monoclonal antibodies were examined and the results were correlated with clinical findings. The expression of surface μ and CAM-1 in B-NHLs and CD25 in T-NHLs were significantly associated with bone marrow involvement. B-NHLs without expression of CD21(B2) and T-NHLs with CD25 were seen more frequently in cases with a LDH value of over 500 units/ml. The positivity rate of Ki-67 on B-NHLs was correlated with serum LDH value, NHL histologic classification, and overall survival. These data indicate that immunophenotyping and determination of the proliferative capacity of NHL are of value not only for confirmation of the histopathologic classification of the tumor but also for assessment of clinical behavior. 相似文献
48.
B Topic E Tani K Tsiakitzis P N Kourounakis E Dere R U Hasen?hrl R H?cker C M Mattern J P Huston 《Neurobiology of aging》2002,23(1):135-143
Here we assessed the effects of i.g. administration of Zingicomb (ZC), a mixture of zingiber officinale and ginkgo biloba extracts, on learning and memory, and on indicators of oxidative stress in aged rats. Effects of ZC (1 and 10 mg/kg) were investigated in 22-24 months old Wistar rats using the Morris water maze, in which they show deficient performance as compared to 3 months old rats in the undrugged state (days 1 and 2). Treatment was administered on days 3 and 4 of training, then over 7 days with training discontinued, and again on days 5 and 6 when training was resumed. Thereafter chronic treatment was maintained over 5 months. 1 mg/kg ZC improved escape learning in the water maze. The two capital indicators of oxidative stress in brain homogenates, the amount of oxidized proteins (assessed as carbonyl group containing proteins) and lipid peroxidation, were significantly reduced in ZC treated animals. Thus, ZC, which had previously been shown to improve inhibitory avoidance learning and to have anxiolytic properties in adult animals, might also facilitate spatial learning in aged animals, and reduces indices of oxidative stress in brain tissue after chronic treatment. 相似文献
49.
Baculovirus gp64 envelope glycoprotein is a major component of the envelope of the budded virus and is involved in virus entry into the host cells by endocytosis. To investigate the cell-surface molecules important for infection of baculovirus into mammalian cells, we constructed a recombinant baculovirus, Ac64-CAluc, which has gp64 and luciferase genes under the polyhedrin and the CAG promoter, respectively. For controls, we constructed recombinant viruses possessing vesicular stomatitis virus (VSV) G protein, mouse hepatitis virus (MHV) S protein, or green fluorescent protein (GFP) gene under the polyhedrin promoter and the luciferase gene under the CAG promoter (AcVSVG-CAluc, AcMHVS-CAluc, and AcGFP-CAluc). Treatment of HepG2 cells with phospholipase C markedly reduced the reporter gene expression by Ac64-CAluc or AcVSVG-CAluc in a dose-dependent manner, whereas AcMHVS-CAluc was shown to be resistant to the treatment. Inhibition with purified lipids and susceptibility to the mutant CHO hamster cell lines deficient in phospholipids synthesis suggest that the interaction of gp64 and phospholipids on the cell surface might play an important role in baculovirus infection into mammalian cells. 相似文献
50.
Nishimura N Nishioka Y Shinohara T Ogawa H Yamamoto S Tani K Sone S 《Journal of immunological methods》2001,253(1-2):113-124
Dendritic cells (DC) are professional antigen-presenting cells in the immune system. Gene transduction of DC with tumor-associated antigen (TAA) or other genes that enhance the immune reaction has been considered theoretically useful for DC-based immunotherapy. However, gene transduction of DC generated from human peripheral blood monocytes has been difficult due to its low efficiency, even when adenoviral vector was used at high multiplicity of infection (MOI). In the present study, we examined the effect of centrifugal force to enhance efficiency of adenovirus-mediated gene transduction into human monocyte-derived DC at various rotor speeds at various temperatures for various times. We judged the transduction efficiency using enhanced green fluorescence protein (EGFP)-expressing adenoviral vector, and the best condition for centrifugal transduction was determined as 2000 x g at 37 degrees C for 2 h at an MOI of 10 or greater. At an MOI of 50 without centrifugation, the gene transduction efficiency was about 66% and mean fluorescence intensity (MFI) of EGFP expression was about 150 (at 37 degrees C for 2 h). With centrifugal transduction (2000 x g at an MOI of 50 at 37 degrees C for 2 h), 86% or more DC were gene-modified, and especially, MFI of EGFP expression was highly enhanced (MFI: about 3100 or greater). Centrifugally gene-transduced DC were not damaged and were thoroughly functional as measured by mixed lymphocyte reaction (MLR). The centrifugal method was also applicable to human monocytes and K562 cells. The centrifugal transduction method with adenoviral vector might be helpful for the generation of gene-modified DC. 相似文献