全文获取类型
收费全文 | 24485篇 |
免费 | 2577篇 |
国内免费 | 859篇 |
专业分类
耳鼻咽喉 | 111篇 |
儿科学 | 539篇 |
妇产科学 | 173篇 |
基础医学 | 4306篇 |
口腔科学 | 342篇 |
临床医学 | 2065篇 |
内科学 | 4100篇 |
皮肤病学 | 625篇 |
神经病学 | 869篇 |
特种医学 | 715篇 |
外国民族医学 | 3篇 |
外科学 | 1994篇 |
综合类 | 3762篇 |
现状与发展 | 10篇 |
预防医学 | 2422篇 |
眼科学 | 320篇 |
药学 | 2221篇 |
19篇 | |
中国医学 | 1534篇 |
肿瘤学 | 1791篇 |
出版年
2024年 | 134篇 |
2023年 | 687篇 |
2022年 | 1218篇 |
2021年 | 1604篇 |
2020年 | 1286篇 |
2019年 | 1016篇 |
2018年 | 894篇 |
2017年 | 1035篇 |
2016年 | 1048篇 |
2015年 | 973篇 |
2014年 | 1378篇 |
2013年 | 1774篇 |
2012年 | 1255篇 |
2011年 | 1268篇 |
2010年 | 1095篇 |
2009年 | 1001篇 |
2008年 | 944篇 |
2007年 | 991篇 |
2006年 | 944篇 |
2005年 | 825篇 |
2004年 | 723篇 |
2003年 | 648篇 |
2002年 | 616篇 |
2001年 | 539篇 |
2000年 | 425篇 |
1999年 | 369篇 |
1998年 | 335篇 |
1997年 | 316篇 |
1996年 | 266篇 |
1995年 | 261篇 |
1994年 | 224篇 |
1993年 | 198篇 |
1992年 | 157篇 |
1991年 | 190篇 |
1990年 | 136篇 |
1989年 | 115篇 |
1988年 | 120篇 |
1987年 | 146篇 |
1986年 | 114篇 |
1985年 | 128篇 |
1984年 | 124篇 |
1983年 | 80篇 |
1982年 | 112篇 |
1981年 | 53篇 |
1980年 | 42篇 |
1979年 | 37篇 |
1978年 | 17篇 |
1977年 | 20篇 |
1976年 | 18篇 |
1975年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
A rotating body consisting of a rotating shaft and bearings inevitably generates voltage and current. The potential difference between the bearing and the shaft is the main cause of electrical corrosion, which causes motor failure, shortened bearing life, and many safety issues. To prevent corrosion, passive shaft-grounding devices use conductive materials and brushes; however, these devices cannot be completely grounded, so there is a difference in local potential, and brush friction generates a shaft current. The cumulative effect causes electrical corrosion; therefore, in this study, an electrical corrosion protection device for the rotating power supply shaft was developed. It detected current and potential difference and established a feedback system on the rotating shaft. It also energized the rotating shaft using an external power supply to eliminate the potential difference on the shaft and reduce electrical corrosion. The result was prolonged motor life and improved stability, operating efficiency, and operability of related equipment. In this study, a rotating-shaft test rig was set up, and a constant current was applied to simulate the potential difference and verify the performance of the anti-corrosion device. Gradually, the design scheme was optimized; the potential difference on the rotating shaft was accurately quantified; and the goal of controlling the potential difference within 2 mV was achieved. Finally, the electrical corrosion protection device was applied to the rotating shaft of a merchant ship, and the current and potential difference on the rotating shaft were monitored for 30 days. The results showed that the device had excellent performance in reducing the potential difference on the rotating shaft and preventing electrical corrosion. 相似文献
92.
Jia-Jun Wu Po-Hsin Lee Zhe-Rong Zheng Yen-Hsiang Huang Jeng-Sen Tseng Kuo-Hsuan Hsu Tsung-Ying Yang Sung-Liang Yu Kun-Chieh Chen Gee-Chen Chang 《Medicine》2022,101(24)
Kirsten rat sarcoma (KRAS) mutation (KRASm) is associated with poor prognosis in non-small cell lung cancer (NSCLC) patients. We have aimed to survey NSCLC patients harboring KRASm in Taiwan, where never-smoking lung adenocarcinoma predominates, and analyze the immune checkpoint inhibitor effect on NSCLC harboring KRASm.NSCLC patients with KRASm were enrolled and tested on programmed death-ligand 1 (PD-L1) expression using available tissue. We analyzed their clinical features, PD-L1 status, responses to ICIs, and overall survival (OS).We studied 93 patients with a median age 66.0 years, 23.7% of whom were women, and 22.6% were never-smokers. The results showed that G12C (36.6%) was the most common KRASm. In 47 patients with available tissue for PD-L1 testing, PD-L1 expression was positive in 66.0% of patients, while PD-L1 ≥50% was higher in ever-smokers (P = .038). Among 23 patients receiving ICI treatment, those with PD-L1 ≥50% experience a 45.5% response rate to ICI. There were benefits from ICI treatment on OS compared with no ICI treatment (median OS 35.6 vs 9.8 months, P = .002) for all of our patients, and for patients with PD-L1 ≥50% (median OS not-reached vs 8.4 months, P = .008). There were no differences in survival across different KRAS subtypes (P = .666).Never-smokers composed more than one-fifth of KRASm in NSCLC in Taiwan. A high PD-L1 expression was related to smoking history and responded well to ICI. ICI treatment improved the OS in NSCLC patients with KRASm, particularly those with PD-L1 ≥50%. 相似文献
93.
94.
Rationale:Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology with diverse clinical and laboratory manifestations, including thrombocytopenia. About 25% of patients with SLE may be affected by thrombocytopenia, many of whom are asymptomatic. Some patients, however, experience platelet counts that drop quite low and predispose them to bleeding. Thrombotic thrombocytopenic purpura (TTP) is defined with a classic pentad of clinical features, such as thrombocytopenia, microangiopathic hemolytic anemia, neurological symptoms and signs, renal symptoms and signs, and fever. The association of TTP and SLE has been sporadically reported in the literature.Patient concerns and diagnosis:We describe a 16-year-old girl with SLE and immune thrombocytopenia, in whom TTP was diagnosed.Interventions and outcomes:She was treated with pulse methylprednisolone, whose platelet counts normalized after therapy with plasmapheresis and an anti-CD20 monoclonal antibody (rituximab).Conclusion:A pediatric patient with SLE and immune thrombocytopenia in whom TTP developed was treated with plasmapheresis and rituximab therapy successfully, though the patient experienced a disease relapsed after 18 months, which was controlled by the same management. 相似文献
95.
Jing Chen Gang Li Chao Wan Yixuan Li Lianci Peng Rendong Fang Yuanyi Peng Chao Ye 《Viruses》2022,14(7)
Pseudorabies virus (PRV), the causative agent of Aujeszky’s disease, is one of the most important infectious pathogens threatening the global pig industry. Like other members of alphaherpesviruses, PRV establishes a lifelong latent infection and occasionally reactivates from latency after stress stimulus in infected pigs. Latent infected pigs can then serve as the source of recurrent infection, which is one of the difficulties for PRV eradication. Virus latency refers to the retention of viral complete genomes without production of infectious progeny virus; however, following stress stimulus, the virus can be reactivated into lytic infection, which is known as the latency-reactivation cycle. Recently, several research have indicated that alphaherpesvirus latency and reactivation is regulated by a complex interplay between virus, neurons, and the immune system. However, with those limited reports, the relevant advances in PRV latency are lagging behind. Therefore, in this review we focus on the regulatory mechanisms in PRV latency via summarizing the progress of PRV itself and that of other alphaherpesviruses, which will improve our understanding in the underlying mechanism of PRV latency and help design novel therapeutic strategies to control PRV latency. 相似文献
96.
Jadwiga Kryczyk-Kozio Ewelina Prochownik Anna Baewska-Gruszczyk Marian Sowiaczek Qian Sun Lutz Schomburg Ewa Ochab Mirosaw Bartyzel Pawe Zagrodzki 《Nutrients》2022,14(14)
The impact of selenium on the course of Hashimoto’s thyroiditis (HT) was mainly assessed by monitoring the titer of antithyroid autoantibodies in most of the studies conducted hitherto. On the other hand, the imbalance in activity of T cells such as Th1, Th2, Th17, and Treg may be relevant in the pathogenesis of this disease. Hence, the assessment of changes in the secretion of cytokines by these cells during selenium supplementation in patients with HT seems to be an important issue and was the main goal of this study. A further aim was to search for correlations among these cytokines, as well as markers of thyroid function, selenium/iodine status in the body, and other biochemical parameters. The group of 29 women with newly diagnosed Hashimoto’s thyroiditis was supplemented with selenium in a dose of 100 µg/day for 6 months. Immunological parameters: interferon γ, tumor necrosis factor α, chemokine CXCL10, interleukin 4, interleukin 1β, interleukin 17, transforming growth factor β, and C-reactive protein, as well as selenium status parameters were determined in serum twice, i.e., before and after supplementation. Selenium supplementation was associated with a change in the production of two cytokines: interferon γ and interleukin 1β, for which a decrease and an increase in concentration were observed, respectively. The partial least squares (PLS) model revealed the presence of many relevant correlations among analyzed parameters. The stage of HT development, degree of thyroid dysfunction, and selenium supplementation of diet are interdependent factors which shape the profile of some cytokines secreted by cells participating in the autoimmunity process. 相似文献
97.
目的:分析淋巴细胞主动免疫与黄体酮及人绒毛膜促性腺激素(HCG)治疗复发性流产患者的疗效。方法:42例复发性流产患者:黄体功能不全所致的流产患者给予黄体酮及HCG;封闭抗体阴性的免疫性RSA的患者给予淋巴细胞主动免疫。结果:23例黄体功能不全所致的患者治疗后,总有效率达100.00%。19例封闭抗体阴性的免疫性RSA的患者治疗后,妊娠率为57.89%。结论:应用淋巴细胞主动免疫与黄体酮及HCG治疗复发性流产患者疗效可靠。 相似文献
98.
采用两种新选择性保护方法由L-丝氨酸和α-酮戊二酸为原料经几步合成了8个目标化合物。体外抑菌该验表明除TMV外,对金葡球菌209P和大肠杆菌44822具有中等到强的活性。 相似文献
99.
Roderik Mrena Seppo Savolainen Heikki Kiukaanniemi Jukka Ylikoski Antti A. Mäkitie 《International journal of audiology》2013,52(6):394-400
The objective of this study was to investigate the effect of tightened hearing protection regulations on tinnitus in the Finnish Defence Forces. The initial study group comprised 252 officers and non-commissioned officers (NCOs), of which 229 were included in the final study group. Subjective symptoms of tinnitus and audiometric test results for these officers and NCOs examined before retirement, from 1984 to 1986 (Period I), and 2003 to 2005 (Period II), were reviewed. Changes in tinnitus reports between the two time periods, during which regulations had been revised, were investigated. Prevalence of tinnitus showed a decline both in officers (from 68% to 63%) and in NCOs (from 76% to 72%) between the two study periods, in accordance with tightened hearing protection regulations. The Cox regression analysis showed a significantly decreased hazard ratio for constant or disturbing tinnitus for Period II. Tinnitus prevalence, especially constant or disturbing tinnitus, in the Finnish Defence Forces was diminished by tightened hearing protection regulations. Tinnitus might be more persistent than hearing loss and does not necessarily improve in direct relation to hearing loss after protective measures. 相似文献
100.
Fan Kou Lei Wu Yan Guo Bailu Zhang Baihui Li Ziqi Huang Xiubao Ren Lili Yang 《癌症生物学与医学(英文版)》2022,19(5):685-695
Objective: Lung cancer is the most common cause of cancer-related deaths worldwide. Somatic copy number alterations(SCNAs) have been used to predict responses to therapies in many cancers, including lung cancer. However, little is known about whether they are predictive of radiotherapy outcomes. We aimed to understand the prognostic value and biological functions of SCNAs.Methods: We analyzed the correlation between SCNAs and clinical outcomes in The Cancer Genome Atlas data for 486 patients wit... 相似文献