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941.
EB病毒(EBV)是一种DNA肿瘤病毒,以往有关EBV致瘤机制的研究主要集中在B淋巴细胞.日前检测发现人类T细胞淋巴瘤也存在EBV感染.近年来研究表明EBV感染可转化T淋巴细胞,EBV可能在T细胞淋巴瘤的发生中起重要作用.观察LMP1在T细胞中的分子生物效应,有助于了解T淋巴细胞中EBV的感染途径、感染方式以及T细胞淋巴瘤的发生机制. 相似文献
942.
目的合成具有抗HIV活性的三环杂环化合物的关键中间体.方法 7-羟基-4-甲基-香豆素、7-羟基-4-甲基喹啉-2(1H)-酮、7-巯基-4-甲基-香豆素分别与3-氯-3-甲基-1-丁炔、3-溴丙炔反应得到相应产物,其结构经波谱确证.结果 4-甲基-香豆素的7位羟基发生正常的双分子亲核取代反应(SN2),得到炔丙基醚产物4、7和10,进一步热环合得到三环杂环化合物5、8和11;7-巯基-4-甲基-香豆素、7-巯基-4-甲基喹啉-2(1H)-酮与3-氯-3-甲基-1-丁炔反应分别得丙二烯醚双分子亲核取代反应(SN2′)产物聚集双键硫醚化合物12和14,且不能进一步热环合成三环杂环.结论 4-甲基-香豆素及4-甲基喹啉-2(1H)-酮的7位羟基、巯基与炔丙基卤代物表现出不同的反应性. 相似文献
943.
神经肌肉接头前阻断剂川楝素抑制大鼠大脑皮层突触体谷氨酸释放(英文) 总被引:2,自引:0,他引:2
目的 阐释川楝素的作用机制 ,为了解递质解释的基本过程提供线索。方法 以大鼠大脑皮层匀浆经密度梯度离心分离获得的突触体作为研究标本 ,分别施加 5 0mmol·L- 1KCl,1.5 μmol·L- 1卡西霉素或 7.5mmol·L- 14 氨基吡啶触发谷氨酸 (Glu)释放。通过检测由Glu氧化脱氢反应与NAD+ 生成的NADH荧光变化测定Glu释放量。结果 川楝素浓度、时间依赖地显著抑制由KCl诱发的Glu释放 ,并主要抑制钙依赖性释放 ;由卡西霉素直接提升胞内钙离子浓度而诱发的Glu释放也被川楝素明显抑制。结论川楝素抑制中枢突触Glu释放 ,该效应与其导致的递质释放机制中钙离子敏感性降低有关。 相似文献
944.
T. Inoue A. Kimura K. Aoki M. Tohma H. Kato 《Archives of disease in childhood. Fetal and neonatal edition》1997,77(1):F52-F56
AIMS—To investigate whether a fetal pathway of bile acid synthesis persists in neonates and infants.
METHODS—3-oxo-Δ4 bile acids were determined qualitatively and quantitatively in the urine, meconium, and faeces of healthy neonates and infants, using gas chromatography-mass spectrometry.
RESULTS—The mean percentage of 3-oxo-Δ4 bile acids in total bile acids in urine at birth was significantly higher than that at 3 or 7 days, and at 1 or 3 months of age. The concentration of this component in meconium was significantly higher than that in faeces at 7 days and at 1 or 3 months of age.
CONCLUSIONS—The presence of large amounts of urinary 3-oxo-Δ4 bile acids may indicate immaturity in the activity of hepatic 3-oxo-Δ4-steroid 5β-reductase in the first week of postnatal life. Large amounts of this component in meconium may be due to the ingestion of amniotic fluid by the fetus during pregnancy.
相似文献
METHODS—3-oxo-Δ4 bile acids were determined qualitatively and quantitatively in the urine, meconium, and faeces of healthy neonates and infants, using gas chromatography-mass spectrometry.
RESULTS—The mean percentage of 3-oxo-Δ4 bile acids in total bile acids in urine at birth was significantly higher than that at 3 or 7 days, and at 1 or 3 months of age. The concentration of this component in meconium was significantly higher than that in faeces at 7 days and at 1 or 3 months of age.
CONCLUSIONS—The presence of large amounts of urinary 3-oxo-Δ4 bile acids may indicate immaturity in the activity of hepatic 3-oxo-Δ4-steroid 5β-reductase in the first week of postnatal life. Large amounts of this component in meconium may be due to the ingestion of amniotic fluid by the fetus during pregnancy.
相似文献
945.
946.
从羊红膻(Pimpinella thellungiana Wolff.)根中分得四个化合物,经理化常数测定和光谱数据解析证明为棕榈酸(Ⅰ)、4-丙烯基苯酚(Ⅱ)、松酯酚(Ⅲ)和新化合物2-甲基-2-羟基-5-甲氧基苯并[d]氢化呋喃-3-酮(Ⅳ)。 相似文献
947.
Enhanced IL-4 but normal interferon-gamma production in children with isolated IgE mediated food hypersensitivity 总被引:2,自引:0,他引:2
Atopic disorders such as atopic dermatitis and asthma have been characterised by an imbalance in interferon-gamma (INF-γ) and IL-4. Whether similar imbalances are found in atopic disorders with different clinical manifestations, such as IgE mediated immediate food hypersensitivity, is not clear. We have examined the in vitro production of INF-γ and IL-4 in peripheral blood mononuclear cells (PBMC) following phytohaemagglutinin stimulation from children with isolated immediate IgE mediated food hypersensitivity (egg, milk, "nut"), children with moderate and severe atopic dermatitis, and normal children. Children with immediate food reactions were excluded if they had a history or evidence of atopic dermatitis or asthma. PBMC from children with IgE mediated food hypersensitivity produced significantly more IL-4 (p = 0.013) but equivalent INF-γ (p=0.26) compared to PBMC from control children. In contrast, PBMC from children with atopic dermatitis produced significantly less INF-γ (p < 0.001) and more IL-4 (p < 0.008) than PBMC from normal children. In addition, there was no difference in IL-4 (p = 0.74) but significantly less INF-γ (p < 0.001) produced by PBMC from the children with atopic dermatitis than food hypersensitivity. We demonstrate that children with IgE mediated food hypersensitivity and no other manifestation of atopic disease have enhanced IL-4 production without the defect in INF-γ production observed in childhood AD and asthma. We postulate that isolated IL-4 enhancement promotes the development of IgE mediated hypersensitivity disorders such as food allergy, whilst the combination of defective INF-γ and enhanced IL-4 production promotes inflammatory atopic disorders such as AD and asthma. 相似文献
948.
949.
Ola Söderberg 《Medical oncology (Northwood, London, England)》1998,15(2):73-78
Although chronic lymphocytic leukaemia of B-cell type (B-CLL) is the most common form of leukaemia in the Western world, several questions about the biology of B-CLL remain to be clarified. To obtain a conceptual model for B-CLL, defined as a relentless accumulation of resting B-CLL cells, it is particularly relevant to ask which cell type is the normal counterpart of B-CLL; what is the site of proliferation; which signals are involved in the recruitment and induction of proliferation and which signals contribute to the survival of the B-CLL cells? The significance of the studies on B-CLL cellsin vitro for the interpretation of thein vivo situation may be questioned since they oversimplify the multiple and complex cellular interactions that occurin vivo. However, thein vitro studies have been instrumental in elucidating signals that may regulate growth, differentiation and survival of B-CLL cells. This knowledge, herein reviewed, can be used to put forward a hypothesis on B-CLL cell regulationin vivo. 相似文献
950.
Vascular cell adhesion molecule 1 (VCAM-1) is a member of immunoglobulin superfamily. The principal ligand for VCAM-1 is integrin
α4β/VLA-4 (very late antigen 4). It was reported that VCAM-1 was expressed on macrophages and dendritic cells, but little
is known about its function on these professional antigen presenting cells (APC). The present study was performed to investigate
the expression of VCAM-1 on macrophages and the role of VCAM-l/VLA-4 in the activation of allogenic T cells by murine macrophages.
We analyzed VCAM-1 expression on peritoneal macrophages and macrophage cell line J774A.1 by fluorescence-activated cell sorting
(FACS). Using neutralizing antibodies, we further analyzed the role of VCAM-l/VLA-4 interaction in macrophage and allogenic
T cell mixed lymphocyte reaction (MLR). We found that VCAM-1 was constitutively expressed on macrophages and its expression
level was upregulated by soluble tumor associated antigen (freeze-thaw lysates of FBL-3 leukemia cells) and TNF-a. In MLR
assays, we observed that blocking VCAM-l/VLA-4 interaction with anti-VCAM-1 or anti-VLA-4 mAbs caused significant inhibition
of the proliferative response and IL-2 production. These results suggest that VCAM-lon macrophages not only facilitates the
cell-to-cell contact through adhesive interaction but also plays a role in the costimulation of T cells via its interaction
with VLA-4 on the T cells.
This work was supported by grants from the National Natural Science Foundation of China.No. (39730420).
This is one of papers of the special issue on gene therapy research (Chin J Cancer Res Vol. 9 No. 4 December, 1997). 相似文献