全文获取类型
收费全文 | 197430篇 |
免费 | 18714篇 |
国内免费 | 7525篇 |
专业分类
耳鼻咽喉 | 1202篇 |
儿科学 | 4666篇 |
妇产科学 | 2740篇 |
基础医学 | 37332篇 |
口腔科学 | 3777篇 |
临床医学 | 12576篇 |
内科学 | 33536篇 |
皮肤病学 | 3252篇 |
神经病学 | 16119篇 |
特种医学 | 3749篇 |
外国民族医学 | 57篇 |
外科学 | 14349篇 |
综合类 | 24482篇 |
现状与发展 | 30篇 |
预防医学 | 8987篇 |
眼科学 | 2298篇 |
药学 | 26131篇 |
21篇 | |
中国医学 | 6957篇 |
肿瘤学 | 21408篇 |
出版年
2024年 | 505篇 |
2023年 | 3093篇 |
2022年 | 6334篇 |
2021年 | 8021篇 |
2020年 | 6802篇 |
2019年 | 7766篇 |
2018年 | 7362篇 |
2017年 | 7271篇 |
2016年 | 7128篇 |
2015年 | 8525篇 |
2014年 | 11928篇 |
2013年 | 13296篇 |
2012年 | 12238篇 |
2011年 | 14532篇 |
2010年 | 12367篇 |
2009年 | 11733篇 |
2008年 | 11123篇 |
2007年 | 9928篇 |
2006年 | 8988篇 |
2005年 | 7660篇 |
2004年 | 6700篇 |
2003年 | 5695篇 |
2002年 | 4435篇 |
2001年 | 3784篇 |
2000年 | 3131篇 |
1999年 | 2838篇 |
1998年 | 2425篇 |
1997年 | 2196篇 |
1996年 | 1890篇 |
1995年 | 1600篇 |
1994年 | 1392篇 |
1993年 | 1172篇 |
1992年 | 978篇 |
1991年 | 875篇 |
1990年 | 724篇 |
1989年 | 613篇 |
1988年 | 541篇 |
1987年 | 430篇 |
1986年 | 423篇 |
1985年 | 801篇 |
1984年 | 822篇 |
1983年 | 576篇 |
1982年 | 649篇 |
1981年 | 508篇 |
1980年 | 418篇 |
1979年 | 367篇 |
1978年 | 281篇 |
1977年 | 222篇 |
1976年 | 206篇 |
1975年 | 144篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
以体外培养的猪主动脉内皮细胞(EC)为模型研究Ilopost对EC抗血栓功能的影响。用放免法、发色底物法测定培养液中6-酮-PGF1α(6-keto-PGF1α),血栓素B2(TXB2)含量,纤溶酶原激活物(PA),纤溶酶原激活物抑制物(PAI)活性及EC环磷酸腺苷(cAMP)含量。结果表明:Iloprost中以使EC生成6-keto-PGF1α,cAMP含量显著增多,TXB2含量显著减少,并使P 相似文献
993.
Male wild (Cavia aperea) and domestic (C. porcellus) guinea pigs were tested in two-bottle choice tests for preferences between glucose solutions of different concentrations and de-ionized water. Wild males showed significant preferences for concentrations between 0.025 and 0.4 M glucose while domestic males preferred only the 0.2 M glucose solution to de-ionized water. C. aperea males also consumed significantly greater volumes of liquid per kg body during the glucose tests than did the C. porcellus males. These comparative results contrast sharply with those obtained by other authors with wild and domestic Norway rats. 相似文献
994.
Masaharu Muranaka Shuji Suzuki Kazuhiro Koizumi Hiroshi Igarashi Hiroshi Okumura Koyo Takeda Kenji Tadokoro Yoshihiko Horiuchi 《The Journal of allergy and clinical immunology》1978,62(5):276-282
All of the five commercially available benzylpenicillin preparations obtained from different sources and a PcG preparation prepared by filtration of a commercial PcG on Sephadex G10 elicited the systemic anaphylactic reactions in guinea pigs which had been immunized with benzylpenicilloyl (BPO)-Ascaris extract conjugate (BPO-As) mixed with aluminum hydroxide gel. These preparations could evoke no such reactions in guinea pigs immunized with BPO-bovine gamma globulin conjugate (BPO-BGG) emulsified with complete Freund's adjuvant. The severity of the systemic anaphylactic reactions correlated significantly with the titers of either 8-day passive cutaneous anaphylactic (8-day PCA) reactions or 4-hr PCA reactions evoked with the same benzylpenicillin preparations. In vitro benzylpenicillin preparation contracted the tracheas of the guinea pigs immunized with BPO-As. These results indicated that the commercially available benzylpenicillin preparations have enough antigenicity to evoke systemic anaphylactic reactions in guinea pigs immunized with BPO-As mixed with aluminum hydroxide gel. Such guinea pigs represent an animal model for investigation of penicillin allergy. 相似文献
995.
M. Vandenbranden J.L. de Coen R. Jeener L. Kanarek J.M. Ruyschaert 《Molecular immunology》1981,18(7):621-631
Interactions between rabbit-γ-immunoglobulins and model membranes (lipid monalayers, planar lipid bilayers, liposomes) have been investigated. No significant interaction was observed with immunoglobulins. However, immunoglobulins dialysed first vs aqueous buffer having pH 2 or 3 and then dialysed against pH 7 buffer presumably adopt a new conformation which allows their bindings to model membranes. This binding is hydrophobic and the immunoglobulin region interacting with the lipid acyl chains is probably located in the heavy chain, as suggested by labelling in this region by a photosensitive probe previously incorporated into the lipid hydrophobic core. Cleavage at the hinge region by papain or pepsin, or heating above 38°C, induces the loss of the hydrophobic conformation responsible for hydrophobic bindings. The binding capacity of immunoglobulins heated above 38°C is restored after momentary dialysis at pH 2. The possible existence of two Ig isomers is discussed in relation to the mechanism of γ-immunoglobulin passage through the endoplasmic membrane and fixation into the plasma membrane. 相似文献
996.
Mohammad M. Al‐Qattan Fowzan S. Alkuraya 《American journal of medical genetics. Part A》2019,179(2):266-279
Cenani–Lenz (C–L) syndrome is characterized by oligosyndactyly, metacarpal synostosis, phalangeal disorganization, and other variable facial and systemic features. Most cases are caused by homozygous and compound heterozygous missense and splice mutations of the LRP4 gene. Currently, the syndrome carries one OMIM number (212780). However, C–L syndrome‐like phenotypes as well as other syndactyly disorders with or without metacarpal synostosis/phalangeal disorganization are also known to be associated with specific LRP4 mutations, adenomatous polyposis coli (APC) truncating mutations, genomic rearrangements of the GREM1‐FMN1 locus, as well as FMN1 mutations. Surprisingly, patients with C–L syndrome‐like phenotype caused by APC truncating mutations have no polyposis despite the increased levels of β catenin. The LRP4 and APC proteins act on the WNT (wingless‐type integration site family) canonical pathway, whereas the GREM‐1 and FMN1 proteins act on the bone morphogenetic protein (BMP) pathway. In this review, we discuss the different mutations associated with C–L syndrome, classify its clinical features, review familial adenomatous polyposis caused by truncating APC mutations and compare these mutations to the splicing APC mutation associated with syndactyly, and finally, explore the pathophysiology through a review of the cross talks between the WNT canonical and the BMP antagonistic pathways. 相似文献
997.
998.
Role of ubiquitin-mediated proteolysis in the pathogenesis of neurodegenerative disorders 总被引:5,自引:0,他引:5
Intraneuronal inclusions containing ubiquitylated filamentous protein aggregates are a common feature of many of the major human neurodegenerative disorders, including Alzheimer's and Parkinson's disease. Loss of function mutations in enzymes of the ubiquitin conjugation/deconjugation pathway are sufficient to cause familial forms of neurodegenerative diseases, suggesting that failure of ubiquitin-mediated proteolysis could also be central to inclusion formation in the more common sporadic cases. Examination of ubiquitin-positive inclusions at the protein level provides evidence of attempted proteasomal proteolysis, however close inspection of the temporal aspects of inclusion formation indicates that ubiquitylation is probably a late event. In this regard, the presence of ubiquitin within inclusions of idiopathic neurodegenerative disorders may indicate not a primary dysfunction of ubiquitin-mediated proteolysis, but rather a secondary, presumably protective cellular response. Within this model, other factors are likely to be initiating in inclusion biogenesis. Consistent with these proposals, non-ubiquitylated forms of the principal ubiquitylated components of Alzheimer's disease neurofibrillary tangles and Parkinson's disease Lewy bodies, tau and alpha-synuclein proteins, respectively, can be degraded by proteasomes in a pathway which does not have an absolute requirement for ubiquitylation. Inhibition of proteasome function in the pathological state, as has been reported in both Alzheimer's and Parkinson's disease, could therefore contribute both to accumulation of non-ubiquitylated forms of aggregation-prone neuronal proteins, as well as impaired clearance of ubiquitylated aggregates. 相似文献
999.
This study attempted to determine whether a prior period of “stress” would elicit the sensitization reaction of the skin to topically applied chemical agents. A subthreshold concentration of 1-chloro-, 2-4, dinitrobenzene (DNCB) was applied to the skin of 40 guinea-pigs, 20 of which had been subjected to repetitive electrical shocks throughout the previous 15 minutes. They were examined 24 hours later, and were retested with DNCB at another site after 9 days for signs of delayed sensitization. The stressed animals exhibited a more severe contact-reaction (p <. 01) after the induction test and also after the delayed test. 相似文献
1000.