全文获取类型
收费全文 | 24290篇 |
免费 | 1493篇 |
国内免费 | 161篇 |
专业分类
耳鼻咽喉 | 292篇 |
儿科学 | 754篇 |
妇产科学 | 720篇 |
基础医学 | 2441篇 |
口腔科学 | 716篇 |
临床医学 | 2029篇 |
内科学 | 5294篇 |
皮肤病学 | 515篇 |
神经病学 | 1115篇 |
特种医学 | 802篇 |
外国民族医学 | 9篇 |
外科学 | 4337篇 |
综合类 | 703篇 |
现状与发展 | 1篇 |
一般理论 | 21篇 |
预防医学 | 1684篇 |
眼科学 | 712篇 |
药学 | 2142篇 |
中国医学 | 156篇 |
肿瘤学 | 1501篇 |
出版年
2023年 | 343篇 |
2022年 | 1001篇 |
2021年 | 1406篇 |
2020年 | 741篇 |
2019年 | 935篇 |
2018年 | 1248篇 |
2017年 | 758篇 |
2016年 | 784篇 |
2015年 | 872篇 |
2014年 | 1080篇 |
2013年 | 1327篇 |
2012年 | 1838篇 |
2011年 | 1869篇 |
2010年 | 967篇 |
2009年 | 798篇 |
2008年 | 1175篇 |
2007年 | 1265篇 |
2006年 | 1099篇 |
2005年 | 948篇 |
2004年 | 897篇 |
2003年 | 755篇 |
2002年 | 699篇 |
2001年 | 329篇 |
2000年 | 316篇 |
1999年 | 292篇 |
1998年 | 158篇 |
1997年 | 115篇 |
1996年 | 101篇 |
1995年 | 106篇 |
1994年 | 69篇 |
1993年 | 55篇 |
1992年 | 131篇 |
1991年 | 120篇 |
1990年 | 114篇 |
1989年 | 103篇 |
1988年 | 97篇 |
1987年 | 94篇 |
1986年 | 97篇 |
1985年 | 85篇 |
1984年 | 69篇 |
1983年 | 87篇 |
1982年 | 36篇 |
1981年 | 44篇 |
1980年 | 32篇 |
1979年 | 78篇 |
1978年 | 44篇 |
1977年 | 52篇 |
1976年 | 41篇 |
1975年 | 44篇 |
1974年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Chromosomal aberrations and micronucleus frequency in nurses occupationally exposed to cytotoxic drugs 总被引:4,自引:1,他引:4
Anwar Wagida A.; Salama Somaia I.; Serafy Mostafa M.EI; Hemida Samia A.; Hafez Ahmed S. 《Mutagenesis》1994,9(4):315-317
In this study, we evaluated the effect of low level occupationalexposure of nurses in a medical oncology unit in Cairo, Egypt,to anticancer drugs. Twenty nurses who constantly handled thesedrugs and 20 controls, matched according to age and sex, wereexamined. Metaphase chromosomes were studied. Percentages ofmetaphases with chromosomal aberrations were significantly higher(P < 0.001) in the exposed group (6.1 ± 2.7) versusthe controls (2.6 ± 1.6). The detected chromosomal aberrationswere in the form of chromatid gaps, chromatid breaks and acentricfragments. Micronucleated peripheral blood lymphocytes werealso analyzed in cytochalasin B treated binucleated lymphocytes.There was significant increase in cells with micronuclei (P< 0.001) in nurses (10.05 ± 4.71) in comparison tothe matched control (5.42 ± 2.22) (P < 0.001). Nursesexposed to the cytotoxic drugs for 相似文献
92.
93.
J. S. Ahmed P. Wiegers S. Steuber E. Schein R. O. Williams D. Dobbelaere 《Parasitology research》1993,79(3):178-182
Theileria annulata andT. parva-infected lymphoblastoid cells were examined for their capacity to produce interferon (IFN). Supernatants of such cells were tested in biological assay for their antiviral activity. OnlyT. parva-infected cells of T-cell origin were capable of producing IFN-gamma. Supernatants of some but not allT. annulata-infected cells showed also antiviral activity, which was greatly reduced after exposure to a pH of 2. Northern-blot analysis of the cells using an IFN-gamma cDNA probe confirmed the results obtained forT. parva-infected cells in a biological assay. No IFN-gamma mRNA was detected inT. annulata-infected cells. The importance of IFN for the pathogenesis of theileriosis is discussed. 相似文献
94.
Sellon DC Knowles DP Greiner EC Long MT Hines MT Hochstatter T Tibary A Dame JB 《Clinical and diagnostic laboratory immunology》2004,11(6):1134-1139
Equine protozoal myeloencephalitis is a progressive neurologic disease of horses most commonly caused by infection with the apicomplexan parasite Sarcocystis neurona. Factors affecting neuroinvasion and neurovirulence have not been determined. We investigated the pathogenesis of infection with S. neurona in horses with severe combined immune deficiency (SCID). Two immunocompetent (IC) Arabian horses and two Arabian horses with SCID were infected orally with 5 x 10(5) sporocysts of S. neurona. Four IC horses and one SCID horse were infected intravenously (i.v.) with 5 x 10(8) merozoites of the WSU-1 isolate of S. neurona. Despite prolonged parasitemia and persistent infection of visceral tissues (skeletal muscle, cardiac muscle, lung, liver, and spleen) as demonstrated by PCR and culture, SCID horses did not develop neurologic signs after oral or i.v. infection. S. neurona was undetectable in the neuronal tissues of SCID horses by either PCR, immunohistochemistry, or culture. In contrast, although parasitemia was undetectable in orally infected IC horses and of only short duration in i.v. infected IC horses, four of six IC horses developed neurologic signs. S. neurona was detectable by PCR and/or culture of neural tissue but not visceral tissue of IC horses with neurologic disease. Infected SCID horses are unable to clear S. neurona from visceral tissues, but the infection does not result in neurologic signs; in contrast, IC horses rapidly control parasitemia and infection of visceral tissues but frequently experience neuroinvasion and exhibit clinical signs of neurologic disease. 相似文献
95.
96.
1. Whole-cell current responses to bath application of glycine, beta-alanine, and taurine were studied in medullary neurons cultured from embryonic rats. 2. Two current components were seen in the responses to bath application of agonist, one component that desensitized and another that did not. 3. The two current components have different dose-response characteristics, with the nondesensitizing component being activated more effectively at lower concentrations than the desensitizing component and also reaching its peak at lower concentrations. The agonist concentrations producing half-maximal responses are 26 +/- 4 (SE, n = 6) and 69 +/- 17 (n = 7) microM for the nondesensitizing and desensitizing components, respectively, for glycine; 54 +/- 7 (n = 9) and 127 +/- 37 (n = 7) microM for beta-alanine; and 153 +/- 24 (n = 9) 443 +/- 99 (n = 3) microM for taurine. Thus, for each component, the order of potency is glycine greater than beta-alanine greater than taurine. 4. When total responses to glycine, beta-alanine, and taurine are compared in the same cells, taurine and beta-alanine are less potent agonists than glycine, with relative potencies of 1:0.4:0.1 for glycine-beta-alanine-taurine. 5. The desensitizing component is more sensitive to strychnine than the nondesensitizing one. The strychnine concentrations that block 50% of the response to a control dose of agonist are 15 and 500 nM for the desensitizing and nondesensitizing components, respectively, for glycine; 60 nM and 1 microM for beta-alanine; and 18 and 500 nM for taurine. 6. The complete occlusion between the responses to glycine and beta-alanine or glycine and taurine suggests that these agonists activate the same receptors. 7. The two current components may be manifestations of one receptor population with complicated kinetics or two independent receptor populations. 相似文献
97.
98.
The rules that govern memory T cell differentiation are not well understood. This study shows that after antigenic stimulation na?ve CD8+ T cells become committed to dividing at least seven times and differentiating into effector and memory cells. Once the parental na?ve CD8+ T cell had been activated, this developmental process could not be interrupted and the daughter cells continued to divide and differentiate in the absence of further antigenic stimulation. These data indicate that initial antigen encounter triggers an instructive developmental program that does not require further antigenic stimulation and does not cease until memory CD8+ T cell formation. 相似文献
99.
Triantafilou K Vakakis E Orthopoulos G Ahmed MA Schumann C Lepper PM Triantafilou M 《European journal of immunology》2005,35(8):2416-2423
Toll-like receptors (TLR) have a key role in regulating immunity against microbial agents. Engagement of TLR by bacterial, viral or fungal components leads to the production and release of inflammatory cytokines. In this study we show that mainly TLR8 and also TLR7 act as the host sensors for human parechovirus 1, a single-stranded RNA (ssRNA) virus. Furthermore, we see that the viral ssRNA genome is detected in endosomal compartments by these TLR, which activate signalling that lead to the synthesis of pro-inflammatory molecules by the host. 相似文献
100.
Ahmed S Ihara K Sasaki Y Nakao F Nishima S Fujino T Hara T 《Experimental and clinical immunogenetics》2000,17(1):18-22
Interleukin (IL)-4 and IL-13 play key roles in the development of atopic asthma. The IL-13 receptor (R) alpha' chain is a component of both IL-4R and IL-13R complexes. By screening the whole coding region of the IL-13Ralpha' gene for polymorphisms, we identified a new polymorphism at nucleotide position 1050 from the ATG start codon. The allelic frequency of the C/T polymorphism in the Japanese population was found to be 0.97:0.03. Because of the low frequency of the T allele, the association study failed to indicate any significant association between this polymorphism and atopic asthma in the Japanese population. Further studies are required in other racial groups with higher frequencies of this polymorphism to elucidate the association. 相似文献