全文获取类型
收费全文 | 275773篇 |
免费 | 22931篇 |
国内免费 | 6490篇 |
专业分类
耳鼻咽喉 | 3719篇 |
儿科学 | 6946篇 |
妇产科学 | 5891篇 |
基础医学 | 24687篇 |
口腔科学 | 8418篇 |
临床医学 | 24603篇 |
内科学 | 28435篇 |
皮肤病学 | 3241篇 |
神经病学 | 14815篇 |
特种医学 | 7321篇 |
外国民族医学 | 18篇 |
外科学 | 24929篇 |
综合类 | 42738篇 |
现状与发展 | 16篇 |
一般理论 | 30篇 |
预防医学 | 34734篇 |
眼科学 | 3842篇 |
药学 | 27154篇 |
395篇 | |
中国医学 | 31532篇 |
肿瘤学 | 11730篇 |
出版年
2024年 | 1117篇 |
2023年 | 5164篇 |
2022年 | 9719篇 |
2021年 | 12858篇 |
2020年 | 12397篇 |
2019年 | 13374篇 |
2018年 | 12070篇 |
2017年 | 10730篇 |
2016年 | 9866篇 |
2015年 | 9247篇 |
2014年 | 17853篇 |
2013年 | 19120篇 |
2012年 | 16211篇 |
2011年 | 17504篇 |
2010年 | 14057篇 |
2009年 | 12329篇 |
2008年 | 11594篇 |
2007年 | 11744篇 |
2006年 | 10166篇 |
2005年 | 8673篇 |
2004年 | 7280篇 |
2003年 | 6556篇 |
2002年 | 5124篇 |
2001年 | 4463篇 |
2000年 | 3898篇 |
1999年 | 3333篇 |
1998年 | 2794篇 |
1997年 | 2573篇 |
1996年 | 2208篇 |
1995年 | 2137篇 |
1994年 | 1866篇 |
1993年 | 1662篇 |
1992年 | 1512篇 |
1991年 | 1410篇 |
1990年 | 1288篇 |
1989年 | 1195篇 |
1988年 | 1047篇 |
1987年 | 924篇 |
1986年 | 935篇 |
1985年 | 2306篇 |
1984年 | 2536篇 |
1983年 | 1584篇 |
1982年 | 2088篇 |
1981年 | 1509篇 |
1980年 | 1333篇 |
1979年 | 1164篇 |
1978年 | 937篇 |
1977年 | 738篇 |
1976年 | 860篇 |
1975年 | 596篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的 探讨新生儿C6PD缺陷病和晚发性维生素K缺乏症的危害与预防措施。方法 回顾分析1995-2000年儿内科住院的1周-2月(不含2月)的婴儿3104例次,其中病死56例。结果 1周-2月的小婴儿占住院患儿的19.34%,其中新生儿G6PD缺陷病239例,占7.70%;晚发性维生素K缺乏症92例,占2.96%。死因的第2、3位分别是晚发性维生素K缺乏症(13例,占23.21%)和新生儿C6PD缺陷病(12例,占21.43%),两者的病死率分别为14.13%和5.02%,极显著高于(x^2=17.59,P<0.01)或相近于(x^2=0.88,P>0.05)肺炎的3.57%。新生儿G6PD缺陷病合并感染占38.49%、低氧血症占23.35%、低血糖占19.25%、酸中毒占15.90%,继发胆红素脑病占13.81%。晚发性维生素K缺乏症出现抽搐占90.22%、胃肠、注射部位出血占60.89%;CT证实颅内出血占98.91%。结论 1周-2月的小婴儿约占住院患儿的两成,新生儿G6PD缺陷病和晚发性维生素K缺乏症的病死率均很高,两者是除肺炎外最主要的死因。提议制定并推广预防这2种疾病的常规措施,并参照国内外相应的现状拟出其具体内容。 相似文献
992.
Many eukaryotic cells depend on proper cell polarization for their development and physiological function. The establishment of these polarities often involve the subcellular localization of a specific subset of proteins, RNAs and organelles. In Drosophila, the microtubule-dependent BicD (BicaudalD) localization machinery is involved in the proper localization of mRNA during oogenesis and embryogenesis and the proper positioning of the oocyte and photoreceptor nuclei. BicD acts together with the minus-end directed motor dynein as well as Egl and Lis-1. The finding that the mammalian homologs of BicD function in retrograde Golgi-to-ER transport has supported the view that BicD may be part of a repeatedly used and evolutionary conserved localization machinery. In this review we focus on the various processes in which BicD is involved during Drosophilian development and in mammals. In addition, we evaluate the interactions between BicD, the dynein localization machinery and associated factors. 相似文献
993.
Stessman J Maaravi Y Hammerman-Rozenberg R Cohen A Nemanov L Gritsenko I Gruberman N Ebstein RP 《Mechanisms of ageing and development》2005,126(2):333-339
In an exploratory study, 11 common polymorphisms were examined for contributing to longevity including: apolipoprotein E (apoE), methylenetetrahydrofolate reductase (MTHFR), cathepsin D (CAD), superoxide dismutase 2 (SOD2), angiotensinogen (AGT) and insulin-like growth factor 2 (IGF2), Leiden factor 7, p53 oncogene, dopamine D4 receptor (DRD4) and the serotonin transporter (SERT). Genotype and allele frequencies of these genes were compared in 224 older (75 years) Jewish Jerusalem residents of Ashkenazi ethnicity to a group of 441 younger subjects (22 years). Nominally significant results provide suggestive evidence in the Ashkenazi group that apoE, MHTFR, SOD2, IGF2 ApaI, and factor VII are risk factors for a single outcome, survival to 75. Overall, the more genetically homogenous Ashkenazi ethnic group showed evidence for association in five genes examined suggesting that future studies in this population would gainfully focus on this ethnic group. 相似文献
994.
BACKGROUND: Bronchial asthma is characterized by airway inflammation, notably because of eosinophils and T cells. Thymus and activation-regulated chemokine (TARC) is known to selectively attract Th2 cells, and is increased in response to interleukin (IL)-4 and IL-13, which share a common receptor, IL-4 receptor alpha (IL-4Ralpha). While corticosteroids have proven, very effective in modifying airway inflammation, the effect of corticosteroids on TARC in asthmatics has been little studied. OBJECTIVE: We examined the effects of inhaled budesonide (BUD) on the expression of TARC and the number of inflammatory cells in bronchial biopsy specimens taken from asthma patients. METHODS: Inhaled BUD 800 mug daily, or placebo was administered for 3 months in a double-blind, parallel-group study, and bronchial biopsies were performed before and after treatment. Biopsy specimens were examined by immunocytochemistry. RESULTS: We observed a significant decrease in the epithelial expression of TARC (P < 0.01) in the BUD group compared with the placebo group. This was accompanied by decreases in the number of eosinophils (P < 0.01), CD3(+) T cells (P < 0.05), and CD4(+) T cells (P < 0.01). A significant correlation was found between changes in epithelial TARC and in IL-4Ralpha immunoreactivity (r(s) = 0.66, P < 0.01). CONCLUSIONS: These findings suggest that corticosteroid asthma treatment can reduce infiltration of the airway by inflammatory cells, an effect modulated by down-regulation of bronchial epithelial TARC expression. 相似文献
995.
Ethinyl estradiol treats collagen-induced arthritis in DBA/1LacJ mice by inhibiting the production of TNF-alpha and IL-1beta 总被引:3,自引:0,他引:3
Subramanian S Tovey M Afentoulis M Krogstad A Vandenbark AA Offner H 《Clinical immunology (Orlando, Fla.)》2005,115(2):162-172
We previously demonstrated the therapeutic effects of ethinyl estradiol (EE), an orally active estrogen and a component of birth control pills, in encephalitogenic autoimmune encephalomyelitis (EAE). In this study, we report the effectiveness of EE in treating collagen-induced arthritis (CIA) induced with bovine type II collagen (bCII) in DBA/1LacJ mice, a CIA susceptible strain. Both low and high doses of EE notably suppressed clinical and histological signs of CIA in a dose-dependent manner compared to vehicle-treated controls. Oral treatment with EE decreased proliferation and secretion of pro-inflammatory factors, TNF-alpha IFN-gamma, MCP-1 and IL-6 by bCII peptide-specific T cells, production of bCII-specific IgG2a antibodies, and mRNA for cytokines, chemokines and chemokine receptors in joint tissue. This is the first report demonstrating effective treatment of joint inflammation and clinical signs of CIA with orally administered ethinyl estradiol, thus supporting its possible clinical use for treating rheumatoid arthritis in humans. 相似文献
996.
Clinicopathological analysis of 143 primary malignant lymphomas in the small and large intestines based on the new WHO classification 总被引:21,自引:0,他引:21
AIM: To study the clinicopathological and immunohistochemical features of 143 cases of primary small and large intestinal non-Hodgkin's lymphoma (NHL) in Japanese patients who presented between 1981 and 2000. METHODS AND RESULTS: The new World Health Organization (WHO) classification was used to classify NHL. The patients included 109 males and 34 females, with an average age of 54.1 years. Tumour sites were as follows: ileocaecal (n = 51, 35.7%), ileum (n = 29, 20.3%), rectum (n = 13, 9.1%), and duodenum (n = 11, 7.7%). Macroscopically, 124 cases (86.7%) were classified as tumorous type, 12 (8.4%) as diffuse infiltration type (erosion, superficial ulceration), five (3.5%) as polyposis type, and only two cases (1.4%) as ulceration type. Immunohistochemically, 122 lesions (85.3%) were of B-cell phenotype and 21 lesions (14.7%) were of T-cell phenotype. According to the WHO classification, of the B-cell lymphomas, 84 cases (68.9%) were large cell, 16 (13.1%) were Burkitt, 10 (8.2%) were marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT), and seven (5.7%) were mantle cell tumours. Among the T-cell lymphomas, 15 (71.4%) were of unspecified type, two (9.5%) were natural killer type, two were anaplastic large-cell lymphomas, one was lymphoblastic, and one was an adult T-cell leukaemia lymphoma. The survival rate for T-cell lymphomas was poorer than for B-cell lymphomas. Among the B-cell lymphomas, mantle cell lymphoma tended to have a poorer prognosis, whereas MALT lymphomas had a better prognosis than other B-cell tumour types. CONCLUSIONS: Our retrospective study of patients with primary malignant lymphomas in the small and large intestines has illustrated the clinical features and outcomes of patients with this disease. 相似文献
997.
Newman JT Surman SR Riggs JM Hansen CT Collins PL Murphy BR Skiadopoulos MH 《Virus genes》2002,24(1):77-92
A complete consensus sequence was determined for the genomic RNA of human parainfluenza virus type 1 (HPIV1) strain Washington/20993/1964 (HPIV1 WASH/64), a clinical isolate that previously was shown to be virulent in adults. The sequence exhibited a high degree of relatedness to both Sendai virus, a PIV1 virus recovered from mice, and human PIV3 (HPIV3) with regard to cis-acting regulatory regions and protein-coding sequences. This consensus sequence was used to generate a full-length antigenomic cDNA and to recover a recombinant wild-type HPIV1 (rHPIV1). Interestingly, the rHPIV1 could be rescued from full-length antigenomic rHPIV1 cDNA using HPIV3 support plasmids, HPIV1 support plasmids, or a mixture thereof. The replication of rHPIV1 in vitro and in the respiratory tract of hamsters was similar to that of its biologically derived parent virus. The similar biological properties of rHPIV1 and HPIV1 WASH/64 in vitro and in vivo, together with the previous demonstration of the virulence of this specific isolate in humans, authenticates the rHPIV1 sequence as that of a wild-type virus. This rHPIV1 can now be used to study the biological properties of HPIV1 and as a substrate to introduce attenuating mutations for the generation of live-attenuated HPIV1 vaccine candidates.An erratum to this article can be found at 相似文献
998.
Quantitative expansion of structural genomic alterations in the spectrum of neuroendocrine lung carcinomas 总被引:3,自引:0,他引:3
Gugger M Burckhardt E Kappeler A Hirsiger H Laissue JA Mazzucchelli L 《The Journal of pathology》2002,196(4):408-415
The pathogenesis and interrelationships of neuroendocrine lung carcinomas are not well understood. Tissue macro-arrays prepared from surgical resection specimens from 35 patients with typical carcinoid (TC), six with atypical carcinoid (AC), 13 with large cell neuroendocrine carcinoma (LCNEC), and 15 with small cell lung carcinoma (SCLC) were investigated by fluorescence in situ hybridization (FISH) and immunohistochemistry. Hybridizations with locus-specific DNA probes demonstrated a high incidence of deletion for the tumour suppressor genes p53 and retinoblastoma (Rb), and for the oncogene cyclin D1, comparable in all carcinoma types. Similarly, an increase of DNA copy number for the Her-2/neu and c-myc oncogenes was noted in all neoplasms. A more detailed quantitative analysis of the results, however, demonstrated increasing numbers of cells harbouring these genomic alterations, from low-grade TC to highly malignant SCLC, with the exception of cyclin D1 deletion. Mutations of the p53 and Rb genes, as assayed by immunohistochemical studies, were observed at high incidence in high-grade carcinomas, compared with a low incidence in the low-grade carcinomas. Conversely, in all carcinoma types, neither membrane-bound Her-2/neu nor nuclear cyclin D1 was detected. It is concluded that structural genomic alterations are frequent in neuroendocrine lung carcinomas and that their occurrence may be underestimated by immunohistochemical studies alone. The quantitative expansion of the Rb, p53, c-myc, and Her-2/neu alterations towards high-grade carcinomas suggests common pathogenetic mechanisms in the spectrum of these neoplasms. 相似文献
999.
1000.
Hubert Walter Hideo Matsumoto Heidi Danker-Hopfe Kailash C. Malhotra Biswa N. Mukherjee 《Journal of human genetics》1997,42(1):193-203
Summary Serum samples from eight endogamous Indian tribal populations of Madhya Pradesh (Dhurwa, Halba, Bhatra, Muria, Maria) and
Orissa (Deshia Khond, Binjhal, Kisan) with a total of n=731 unrelated individuals were typed for G1M (1,2,3,17), G3M (5,10,11,13,14,15,16,21,26),
and KM (1). In seven of these populations five different GM haplotypes were found:GM*1,17;21,26; GM*1,17;10,11,13,15,16; GM*1,2,17;21,26; GM*1,3;5,10,11,13,14,26; andGM*3;5,10,11,13,14,26. In the Kisan sample the haplotypeGM*1,2,17; 21,26 is absent. The intergroup variability in the distribution of these haplotypes is considerable and statistically highly significant.
The reasons for that can be attributed to the ethnohistory and to the genetic isolation of these eight endogamous tribal populations.
The GM haplotype distribution pattern of all these groups is quite different from that of the non-tribal populations of India,
whereas it is in good agreement with that of the so far tested other tribal populations from India. This can be explained
by different origin and history of the Indian tribal and non-tribal populations. In the KM system, too, remarkable variability
is seen in the distribution of phenotype and allele frequencies among the eight tribal populations under study. 相似文献