首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6631篇
  免费   334篇
  国内免费   28篇
耳鼻咽喉   55篇
儿科学   167篇
妇产科学   46篇
基础医学   849篇
口腔科学   197篇
临床医学   407篇
内科学   1956篇
皮肤病学   76篇
神经病学   468篇
特种医学   168篇
外科学   992篇
综合类   39篇
预防医学   230篇
眼科学   254篇
药学   469篇
中国医学   13篇
肿瘤学   607篇
  2023年   45篇
  2022年   74篇
  2021年   102篇
  2020年   63篇
  2019年   79篇
  2018年   102篇
  2017年   96篇
  2016年   96篇
  2015年   116篇
  2014年   141篇
  2013年   177篇
  2012年   333篇
  2011年   333篇
  2010年   197篇
  2009年   177篇
  2008年   340篇
  2007年   417篇
  2006年   389篇
  2005年   357篇
  2004年   320篇
  2003年   346篇
  2002年   350篇
  2001年   263篇
  2000年   247篇
  1999年   208篇
  1998年   98篇
  1997年   78篇
  1996年   86篇
  1995年   58篇
  1994年   42篇
  1993年   36篇
  1992年   117篇
  1991年   107篇
  1990年   94篇
  1989年   91篇
  1988年   103篇
  1987年   88篇
  1986年   97篇
  1985年   78篇
  1984年   64篇
  1983年   44篇
  1982年   20篇
  1980年   31篇
  1979年   35篇
  1977年   17篇
  1975年   27篇
  1974年   26篇
  1972年   20篇
  1967年   19篇
  1966年   17篇
排序方式: 共有6993条查询结果,搜索用时 15 毫秒
71.
BACKGROUND: Itching in humans is attenuated by mu-opioid receptor antagonists. ICR mice display increases in scratching behavior upon induction of IgE-mediated passive cutaneous anaphylaxis (PCA), or intradermal injection of compound 48/80 or histamine. METHODS: Cutaneous reactions were induced in ICR mice by IgE-mediated PCA, compound 48/80 and histamine, and the scratching behavior associated with the cutaneous reactions was evaluated. RESULTS: Naloxone and nalmefene reduced the incidence of scratching behavior associated with PCA. Naloxone also inhibited the induction of scratching behavior caused by compound 48/80 and histamine. Naloxone did not affect the increase in vascular permeability caused by PCA and injection of compound 48/80. CONCLUSION: Scratching behavior in mice may be induced by a sensation or a mechanism similar to itching in humans and should become a useful model for examining itching in humans.  相似文献   
72.
In order to investigate the role of polymorphonuclear leukocytes (PMN) in the distribution of antigen in various organs and in the development of nephritis, chronic serum sickness type nephritis was induced in both anti rat PMN rabbit serum (APS) treated and normal rabbit serum (NRS) treated rats by preimmunization with bovine serum albumin (BSA) and subsequent daily intravenous administration of BSA for 4 weeks. Kinetic studies using radiolabeled BSA showed that accumulation of BSA after the first intravenous administration was reduced by APS treatment in the liver, lungs and spleen and increased in the circulation, but was not affected in the kidneys and glomeruli. Histological studies supported the above findings. After 4 weeks of BSA administration, the BSA accumulation in the kidneys and glomeruli was significantly less in APS treated rats than in NRS treated ones, while amounts of BSA in the circulation and other organs were not different between the two groups. Furthermore, APS treatment reduced proteinuria, PMN infiltration and IC deposition in the glomeruli. These observations indicate that PMN play a partial role in IC deposition in the glomerular capillary walls and subsequent destruction of glomerular permeability in chronic serum sickness-type nephritis. Acta Pathol Jpn 39 : 619-629, 1989.  相似文献   
73.
A peptidoglycan layer of Treponema pallidum kazan was isolated by solubilization of whole cells with 1% warm sodium dodecyl sulfate and subsequent digestion of an insoluble residue with proteases. Electron microscopy revealed that the peptidoglycan was isolated as a single-layered sacculus of less than 5 nm in thickness, freed from axial filaments and an envelope sheath. An isolated peptidoglycan fraction was mainly composed of glucosamine, muramic acid, alanine, glutamic acid, ornithine, and glycine in molar ratios of 0.65:0.68:1.63:1.00:0.75:1.03. Amino (N)- and carboxyl (C)-terminal amino acid analyses suggested the involvement of at least a part of the glycine residue in cross-linking between the amino group of ornithine residue at one strand of the stem peptide subunit and the carboxyl group of alanine of the neighboring strand. The treponemal peptidoglycan lacked the immunoadjuvant activity both to stimulate antibody production and to induce delayed-type hypersensitivity against ovalbumin, as well as the properties necessary to stimulate guinea pig and mouse splenocytes and guinea pigs peritoneal macrophages, unlike the cell walls or peptidoglycans (group A type of Schleifer and Kandler's classification, Bacteriol. Rev. 36:407-477, 1972) isolated from many bacterial species parasitic to the mammal. However, the peptidoglycan activated the human complement system through the alternative pathway, as well as the classical one, and caused a liberation of 5-hydroxytryptamine in rabbit blood platelets in a similar manner to the cell wall peptidoglycans of both group A and B types.  相似文献   
74.
Adult T-cell leukaemia/lymphoma (ATLL), is a malignant condition associated with human T-cell leukaemia virus type I (HTLV-I). Usually, although not uniformly, histopathological examination of the lymph nodes shows a pleomorphic type. In addition, some patients with pre-overt ATLL show a Hodgkin's disease-like morphology and lymph nodes in non-neoplastic carriers show features of lymphadenitis. To characterize further the clinicopathological features of HTLV-I-associated lymphadenopathy, the histopathological features of the lymph nodes of 289 patients were classified into five types: lymphadenitis ( n=14), Hodgkin's-like (Hodgkin's) ( n=18), pleomorphic (medium and large cells) ( n=219), pleomorphic small cell ( n=11), and anaplastic large cell (ALC) ( n=27). Survival data were analysed according to the histopathological features of the lymph nodes. The pleomorphic type, which showed typical features of ATLL, was associated with a highly aggressive course and an initially high mortality, followed by a rapid decrease in survival. This pattern was also observed in patients with the ALC type. All cases with lymphadenitis were still alive at the end of the study, while survival progressively decreased in the Hodgkin's type. The small cell type showed an initial rapid decrease in survival followed by a plateau. These results show that the survival trends of patients with pleomorphic and anaplastic lymph node lesions are similar to those with ATL lymphoma, while patients with the lymphadenitis type of lesion were considered to have a non-neoplatic status. There is at present no effective therapy for ATLL, but in the future, these classification and survival data might be useful for the selection of appropriate chemotherapeutic regimens for patients with ATLL.  相似文献   
75.
This study investigated whether interleukin-10 (IL-10) gene promoter region polymorphisms are associated with susceptibility to or clinical presentation of type 1 diabetes. The frequency of -1082G/A, -819C/T, and -592C/A polymorphisms was analyzed in 128 Japanese patients with type 1 diabetes and in 107 healthy control subjects in a case-controlled study. The allelic and haplotypic frequencies of the IL-10 gene promoter region polymorphisms were similar in patients with type 1 diabetes and in control subjects. However, the -819T and -592A allele were associated with adult-onset (>18 years) of the disease (p = 0.037). Furthermore, the frequency of ATA haplotype was increased in adult-onset patients than that in early-onset patients (< or =18 years; p = 0.037). Among the genotypes comprising ATA haplotype, the frequency of ATA/ATA was significantly higher in adult-onset patients than in early-onset patients (p = 0.004). These results suggest that the IL-10 gene promoter polymorphisms are associated with the age-at-onset in Japanese patients with type 1 diabetes.  相似文献   
76.
77.
A clearance kinetic study of intravenously administered 125I-labeled aggregated human IgG (125I-AHIgG) from the circulation and its distribution in various organs was performed weekly during the course in a model of experimental immune complex glomerulonephritis which was induced in rats immunized 8 weeks previously with 6 times a week administration of 2 mg of bovine serum albumin (BSA) for 4 weeks from week 8 to 12. The removal rates of the injected 125I-AHIgG from the circulation were retarded in nonproteinuric rats of week 9 and 10, at almost every checked point (p-value was <0.01). The clearance in those rats with severe proteinuria returned to the level of the control and of rats in week 8. The distribution of 125I-AHIgG in the liver 4 hours after the administration revealed a considerable decrease in non-overt proteinuric rats of weeks 9, 10, and 11. A similar tendency of decreasing depositions of the radioactivity was shown in the spleen at each 4 hours. In contrast, the uptakes in the kidney and lung at the final week of 12 were larger. Delayed clearance from the circulation and a decreasing handle of the injected macromolecule in the liver and possibly in the spleen may suggest the presence of some impairment of the MPS function in the course of this experimental glomerulonephritis.  相似文献   
78.
Summary To evaluate the effects of calcium disodium ethylenediamine tetraacetate (CaEDTA) on the concentrations of lead, zinc and copper in plasma, erythrocyte and urine, and the delta-aminolevulinic acid dehydratase (ALAD) activity in erytrocyte, we administered CaEDTA in 1-h intravenous infusion to ten male gun metal founders with blood-lead concentration of 39 to 64 g/dl (mean 49 g/dl). We found that the plasma concentration of lead, following a rapid rise within the first 3 h, fell temporarily to the level significantly lower than the initial level 19 h after start of the infusion. The plasma concentration of zinc fell to the minimal level 5 h after the infusion; and the erythrocyte concentration of zinc and the ALAD activity concurrently rose to the maximal level 5 h after the infusion. By contrast, no significant alteration was observed in the concentrations of copper in plasma and erythrocyte. The maximal level of urinary metal excretion was attained during the period between 1 and 2 h after start of CaEDTA infusion for lead; within 2 h for zinc; and between 2 and 4 h for copper. The urinary metal excretion returned to the initial level 14 to 24 h after infusion for zinc and copper; but lead excretion was still higher than the initial level during this period. The difference in the kinetics of the three metals following CaEDTA injection is discussed in the light of these findings.  相似文献   
79.
The standing potential of the eye is decreased by intravenous administration of hypertonic solutions. This hyperosmolarity-induced response has been recorded in normal subjects by the use of electro-oculography (EOG) in the dark. An intravenous administration of Fructmanit® (1.4 × 103 mOsmol) (150 500ml, 2.37 9.70ml/kg, 0.08 0.36 ml/kg/min) was used to evoke the hyperosmolarity response. The amplitude of the response was expressed in percentage, V0 – Vmin/V0 × 100, where V0 is the base value of the EOG before administration of the hypertonic solution and Vmin is a minimum EOG amplitude after administration. The distribution of the amplitude of the hyperosmolarity response was approximated by the normal distribution in normal subjects. The minimum, the maximum, the mean and the standard deviation of the amplitude of the hyperosmolarity response were respectively 34.2%, 52.3%, 42.6% and 4.6% in normal subjects. The normal range of the hyperosmolarity response would be 33.4 51.8% (M ± 2SD). The hyperosmolarity response, which originates mainly in the retinal pigment epithelium, is a useful new quantitative and specific test of the activity of the retinal pigment epithelium in clinical practice.  相似文献   
80.
The hyperosmolarity response of the ocular standing potential was recorded in unilateral rhegmatogenous retinal detachment (8 eyes) and in the fellow healthy eye (8 eyes). The hyperosmolarity response was greatly suppressed (M-4 SD: M and SD indicate respectively the mean and the standard deviation in normal subjects) in all affected eyes (p < 0.005), and slightly abnormal in 2 fellow eyes. The L/D ratio was normal in 2 affected eyes and in all fellow eyes. The hyperosmolarity response in the affected eyes was still greatly suppressed 14 months after successful surgical treatment.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号