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   3086篇
  免费   197篇
  国内免费   101篇
耳鼻咽喉   25篇
儿科学   62篇
妇产科学   60篇
基础医学   738篇
口腔科学   32篇
临床医学   357篇
内科学   515篇
皮肤病学   36篇
神经病学   84篇
特种医学   61篇
外国民族医学   1篇
外科学   110篇
综合类   407篇
预防医学   175篇
眼科学   8篇
药学   188篇
中国医学   57篇
肿瘤学   468篇
  2023年   49篇
  2022年   83篇
  2021年   144篇
  2020年   126篇
  2019年   91篇
  2018年   102篇
  2017年   99篇
  2016年   91篇
  2015年   137篇
  2014年   190篇
  2013年   223篇
  2012年   175篇
  2011年   171篇
  2010年   152篇
  2009年   158篇
  2008年   123篇
  2007年   158篇
  2006年   143篇
  2005年   111篇
  2004年   103篇
  2003年   93篇
  2002年   88篇
  2001年   65篇
  2000年   75篇
  1999年   65篇
  1998年   47篇
  1997年   44篇
  1996年   51篇
  1995年   53篇
  1994年   38篇
  1993年   29篇
  1992年   17篇
  1991年   22篇
  1990年   19篇
  1989年   13篇
  1988年   8篇
  1987年   5篇
  1986年   5篇
  1985年   9篇
  1984年   3篇
  1983年   1篇
  1982年   2篇
  1980年   1篇
  1978年   1篇
  1907年   1篇
排序方式: 共有3384条查询结果,搜索用时 236 毫秒
81.
The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is one of the most commonly deregulated pathways in human cancers. PI3K comprises a catalytic (p110α) and regulatory subunit (p85), and p110α is encoded by the PIK3CA gene. Here, we summarize the known genetic alterations, including amplifications and mutations, of the PIK3CA oncogene in oral cancer. We discuss in detail PIK3CA mutations and their mutual exclusivity with pathway genes in addition to the incidence of PIK3CA mutations in relation to ethnicity. We describe the constitutive activation of PI3K signaling, oncogenicity, and the genetic deregulation of the PIK3CA gene and its association with oral cancer disease stage. We emphasize the importance of therapeutically targeting the genetically deregulated PIK3CA oncogene and its signaling. We also discuss the implications of targeting Akt and/or mTOR, which are the downstream effectors of PI3K that may possibly pave the way for molecular therapeutic targets for PIK3CA-driven oral carcinogenesis. Furthermore, this critical review provides a complete picture of the PIK3CA oncogene and its deregulation in oral cancer, which may facilitate early diagnosis and improve prognosis through personalized molecular targeted therapy in oral cancer.  相似文献   
82.
Loop-mediated isothermal amplification (LAMP) is becoming an established nucleic acid amplification method offering rapid, accurate, and cost-effective diagnosis of infectious diseases. We retrospectively evaluated 78 consecutive HIV-uninfected patients who underwent LAMP method for diagnosing Pneumocystis pneumonia (PCP). Diagnosis of PCP was made by the detection of Pneumocystis jirovecii (P. jirovecii) with positive LAMP or conventional staining (CS) (Grocott methenamine silver staining or Diff-Quick™) on the basis of compatible clinical symptoms and radiologic findings. Additionally, we reviewed HIV-uninfected immunocompromised patients who underwent subcontract PCR as a historical control. LAMP was positive in 10 (90.9%) of 11 positive-CS patients. Among 13 negative-CS patients with positive LAMP, 11 (84.6%) had PCP, and the remaining 2 were categorized as having P. jirovecii colonization. LDH levels in negative-CS PCP were higher than in positive-CS PCP (p = 0.026). (1 → 3)-β-D-glucan levels in negative-CS PCP were lower than in positive-CS PCP (p = 0.011). The interval from symptom onset to diagnosis as PCP in LAMP group (3.45 ± 1.77 days; n = 22) was shorter than in subcontract PCR group (6.90 ± 2.28 days; n = 10; p < 0.001). As for patients without PCP, duration of unnecessary PCP treatment in LAMP group (2; 2–3 days; n = 10) was shorter than in subcontract PCR group (7; 7–12.25 days; n = 6; p = 0.003). LAMP showed higher sensitivity (95.4%) and positive predictive value (91.3%) than subcontract PCR did. Pneumocystis LAMP method is a sensitive and cost-effective diagnostic method and is easy to administer in general hospitals. In-house LAMP method would realize early diagnosis of PCP, resulting in improving PCP prognosis and reducing unnecessary PCP-specific treatment.  相似文献   
83.
We assessed c-MET expression and oncogene amplification in a cohort enrolling 92 surgically treated penile squamous cell carcinomas (PSCCs). A tissue microarray was constructed for c-MET immunohistochemistry (IHC) and chromogenic silver in situ hybridization (SISH). Two independent pathologists evaluated IHC by employing the breast cancer scoring rules, and scored the presence of MET oncogene amplification and/or polysomy-7. Eighty study cases (87%) showed c-MET expression. No study case had MET oncogene amplification, but 42 patients (45.7%) had polysomy-7. Polysomy-7 showed a significant positive correlation with c-MET expression (ρ = 0.323, p = 0.002). Neither c-MET expression nor polysomy-7 was associated with histopathologic parameters or with cancer-specific survival (median post-surgical follow-up 32 months). Our data suggest that the majority of PSCCs exhibit c-MET expression which is not associated with oncogene amplification, but might be attributable to polysomy-7. Further studies should investigate the expression and activation of downstream molecules functionally involved in c-MET pathway signaling, and clarify the so far unresolved role of c-MET inhibitors as potential targeted therapies in PSCCs with metastatic dissemination.  相似文献   
84.
《Vaccine》2020,38(2):143-149
Recently, outbreaks of adenoviral gizzard erosion (AGE) have been documented in pullets and layers housed free range and in enriched cage systems characterized by increased mortality and a negative impact on egg production. In the present study the pathogenicity of a fowl adenovirus serotype 1 (FAdV-1) field strain as well as the aetiological role of a FAdV-8a strain, both isolated from AGE affected pullets, were investigated in vivo in 20-week-old specific-pathogen-free (SPF) layer-type chickens. Furthermore, the efficacy of a single (week 17) and double (week 14 and 17) application of a live vaccine consisting of an apathogenic FAdV-1 (CELO strain) against challenge with virulent FAdV-1 was investigated.For the first time, AGE was successfully reproduced in adult birds after oral infection of 20-week-old SPF birds with a virulent FAdV-1 field isolate, characterized by pathological changes of the gizzard from 7 days post challenge onwards. In addition, a negative impact of the FAdV-1 infection on the development of the reproductive tract was observed. Thus, confirming the pathogenicity and aetiological role of FAdV-1 in the development of AGE and economic losses due to AGE in layers. In contrast, no pathological changes were observed in birds infected with FAdV-8a.Independent of a single or double application of the live FAdV-1 vaccine strain CELO, no gross pathological changes were observed in gizzards post challenge with the virulent FAdV-1, indicating that complete protection of layers against horizontal induction of AGE was achieved. Nonetheless, virulent FAdV-1 was detected in cloacal swabs and gizzards in both vaccinated groups post challenge determined by the application of an amplification refractory mutation system quantitative PCR used to differentiate between vaccine and challenge strains.  相似文献   
85.
In this article, we review the current literature assessing the application and benefits of connected hearing technologies, as well as their potential to improve accessibility to and affordability of hearing healthcare. Over the past decade, there has been a proliferation of hearing devices that connect wirelessly to smartphone technologies via Bluetooth. These devices include (1) smartphone-connected hearing aids that must be obtained from a licensed audiologist or hearing aid dispenser; (2) direct-to-consumer devices, such as personal sound amplification products; and (3) smartphone-based hearing aid applications (or apps). Common to all these connected devices is that they permit the user to self-adjust and customize their device programs via an accompanying smartphone app. There has been a growing body of literature assessing connected hearing devices in adults living with hearing loss. Overall, the evidence to date supports the notion that all connected hearing devices can improve accessibility to and affordability of amplification. It is unclear, however, whether connected technologies are a clinically effective alternative to traditional hearing aids. Even so, the impact of connectivity is especially pertinent given the sudden disruption caused by the recent global COVID-19 pandemic, whereby connected technologies enable patients to receive treatment through mobile-based, tele-audiology platforms.  相似文献   
86.
87.
Diagnosis of gonorrhoea is an ongoing challenge. The organism is fastidious requiring meticulous collection and transport for successful cultivation. Asymptomatic infections are common which go undetected by conventional methods thereby leading to continued transmission and the risk of complications. The nucleic acid amplification tests, now increasingly used in developed countries, offer improved sensitivity compared to bacterial culture. However, these continue to suffer sequence related problems leading to false positive and false negative results. Further, these cannot be used for generation of data on antibiotic susceptibility because genetic markers of antibiotic resistance to recommended therapies have not been fully characterised. They are unaffordable in a setting like ours where reliance is placed on syndromic approach for sexually transmitted infection (STI) management. The use of syndromic approach has resulted in a considerable decline in the number of Neisseria gonorrhoeae isolates that have been cultured for diagnostic purposes. Many laboratories formerly doing so are no longer performing culture for gonococci, and the basic skills have been lost. There is a need to not only revive this skill but also adopt newer technologies that can aid in accurate diagnosis in a cost-effective manner. There is room for innovation that can facilitate the development of a point-of-care test for this bacterial STI.  相似文献   
88.
89.
90.
Coronavirus disease 2019 (COVID‐19) caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has become a global pandemic. Therefore, convenient, timely and accurate detection of SARS‐CoV‐2 is urgently needed. Here, we review the types, characteristics and shortcomings of various detection methods, as well as perspectives for the SARS‐CoV‐2 diagnosis. Clinically, nucleic acid‐based methods are sensitive but prone to false‐positive. The antibody‐based method has slightly lower sensitivity but higher accuracy. Therefore, it is suggested to combine the two methods to improve the detection accuracy of COVID‐19.  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