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   828篇
  免费   51篇
  国内免费   1篇
耳鼻咽喉   7篇
儿科学   39篇
妇产科学   13篇
基础医学   116篇
口腔科学   47篇
临床医学   63篇
内科学   182篇
皮肤病学   17篇
神经病学   54篇
特种医学   15篇
外科学   97篇
综合类   9篇
预防医学   46篇
眼科学   42篇
药学   63篇
中国医学   5篇
肿瘤学   65篇
  2023年   11篇
  2022年   29篇
  2021年   77篇
  2020年   48篇
  2019年   37篇
  2018年   41篇
  2017年   34篇
  2016年   51篇
  2015年   39篇
  2014年   59篇
  2013年   49篇
  2012年   72篇
  2011年   63篇
  2010年   43篇
  2009年   27篇
  2008年   38篇
  2007年   46篇
  2006年   33篇
  2005年   20篇
  2004年   15篇
  2003年   14篇
  2002年   10篇
  2001年   2篇
  2000年   1篇
  1999年   5篇
  1998年   3篇
  1997年   2篇
  1995年   1篇
  1990年   1篇
  1989年   1篇
  1985年   2篇
  1984年   2篇
  1981年   2篇
  1979年   1篇
  1973年   1篇
排序方式: 共有880条查询结果,搜索用时 31 毫秒
861.
862.
863.
An important question in memory development is understanding the differences between effector CD8 T cells that die versus effector cells that survive and give rise to memory cells. In this study, we provide a comprehensive phenotypic, functional, and genomic profiling of terminal effectors and memory precursors. Using killer cell lectin-like receptor G1 as a marker to distinguish these effector subsets, we found that despite their diverse cell fates, both subsets possessed remarkably similar gene expression profiles and functioned as equally potent killer cells. However, only the memory precursors were capable of making interleukin (IL) 2, thus defining a novel effector cell that was cytotoxic, expressed granzyme B, and produced inflammatory cytokines in addition to IL-2. This effector population then differentiated into long-lived protective memory T cells capable of self-renewal and rapid recall responses. Experiments to understand the signals that regulate the generation of terminal effectors versus memory precursors showed that cells that continued to receive antigenic stimulation during the later stages of infection were more likely to become terminal effectors. Importantly, curtailing antigenic stimulation toward the tail end of the acute infection enhanced the generation of memory cells. These studies support the decreasing potential model of memory differentiation and show that the duration of antigenic stimulation is a critical regulator of memory formation.  相似文献   
864.
Distinction of primary skin adnexal carcinomas from cutaneous metastasis of adenocarcinomas is challenging. In this study, we evaluated podoplanin immunoreactivity in a series of primary skin adnexal tumors and adenocarcinomas metastatic to skin using a D2-40 antibody. The initial test series were composed of a total of 93 cases including 32 primary skin adnexal carcinomas, 46 benign primary adnexal tumors, and 15 cutaneous metastatic adenocarcinomas. We found that variable D2-40 reactivity was seen in all of the primary cutaneous carcinomas including sebaceous carcinomas (10/10), squamous cell carcinomas (10/10), porocarcinomas (4/4), trichilemmal carcinomas (4/4), skin adnexal carcinomas not otherwise specified (4/4), and in the majority of benign skin adnexal tumors. In contrast, no podoplanin immunoreactivity was seen in any of the 15 (0/15) cutaneous metastases. To confirm the initial findings and to further explore the utility of podoplanin reactivity in the distinction of these tumors, we also examined a test set of 35 unknown cases, including 21 adenocarcinomas metastatic to skin and 14 primary adnexal tumors, in a blinded fashion. In this test set of cases, podoplanin was negative in 22 cases and positive in 13 cases. Of the 22 podoplanin negative cases, 20 were proven to be metastatic adenocarcinoma. Of the 13 D2-40 positive cases, 12 were proven to be primary adnexal tumors. Our results suggest that podoplanin can be a useful tool to distinguish primary skin adnexal carcinomas form adenocarcinomas metastatic to skin with high sensitivity (94.5%) and specificity (97.2%).  相似文献   
865.
A great deal of clinical and research attention has been paid to understanding and explaining child sex offenders' social cognition. Cognitive distortions have been implicated as a core feature of child sex offenders' offense supportive cognition. The primary aim of this paper is to critically evaluate the phenomenon of cognitive distortions as currently understood with respect to child sex offenders: it reviews the theoretical and research literature and highlights the implications for clinical practice.  相似文献   
866.
867.
Background contextCervical discography is not uniformly used in part because of the fear of discitis. Studies report widely varying rates of this life-threatening infection.PurposeThe aim of this study was to estimate the incidence of discitis after cervical discography, delineate the consequences of discitis, and identify factors that may influence this complication.Study designMeta-analysis.MethodsStudies pertaining to cervical discography were identified by a literature review and bibliographic search. These were screened for inclusion into the meta-analysis by two reviewers. Data were collected on a wide range of clinical and demographic variables including age, gender, morbidities, number of patients, number of discograms, use of prophylactic antibiotics, type of surgical prep, number of needles used, and the number of patients and discs infected. Primary data were used to calculate the incidence of discitis per patient and per disc.ResultsFourteen studies were included in the analysis. Both procedural details and demographic information on patients were missing from eight studies. The mean age of patients ranged from 41 to 47 years, and gender distribution varied greatly. Antibiotics use was reported in three studies. Cervical discography was complicated by postprocedural discitis in 22 of 14,133 disc injections (0.15%) and 21 of 4,804 patients (0.44%). Only one patient suffered from an infection at more than one spinal level.ConclusionsThe rate of discitis after cervical discography is relatively low. This can perhaps be further decreased by the use of prophylactic intradiscal antibiotics. Should the ability of cervical discography to improve surgical outcomes be proven, the fear of discitis should not preclude performance of disc provocation.  相似文献   
868.
869.
Cancer chemotherapies suffer from multi drug resistance, high non-specific toxicity and heterogeneity of tumors. We report a method of plasmonic nanobubble-enhanced endosomal escape (PNBEE) for the selective, fast and guided intracellular delivery of drugs through a self-assembly by cancer cells of separately targeted gold nanoparticles and encapsulated drug (Doxil). The co-localized with Doxil plasmonic nanobubbles optically generated in cancer cells released the drug into the cytoplasm thus increasing the therapeutic efficacy against these drug-resistant cells by 31-fold, reducing drug dose by 20-fold, the treatment time by 3-fold and the non-specific toxicity by 10-fold compared to standard treatment. Thus the PNBEE mechanism provided selective, safe and efficient intracellular drug delivery in heterogeneous environment opening new opportunities for drug therapies.  相似文献   
870.
APOBEC3B deletion polymorphism has been associated with risk of HIV‐1 acquisition and its progression. Therefore, we aimed to investigate the association of APOBEC3B ins/del polymorphism with risk of acquisition of HIV‐1 and its progression. In the present case–control study, we enrolled a total of 150 HIV‐infected individuals and 150 healthy controls. Polymorphism for APOBEC3B gene was genotyped by PCR. APOBEC3B ID, DD genotypes, and D allele were associated with higher risk of acquisition of HIV‐1 (p = 0.004, OR = 4.96; p = 0.03, OR = 3.55; and p = 0.004; OR = 1.60). The individuals with ID genotypes and combined genotype ID+DD of APOBEC3B in the presence of tobacco and alcohol showed the higher risk of advancement of HIV disease; however, risk could not reach statistical significance (OR = 1.14, 95% CI: 0.59–2.18; OR = 1.33, 95% CI: 0.83–2.15 and OR = 1.44, 95% CI: 0.77–2.69; OR = 1.50, 95% CI: 0.94–2.40). Individuals in advanced HIV disease stage and ID genotype and combined genotype ID + DD of APOBEC3B were more likely to be associated with advanced HIV disease stage but risk could not reach significant (OR = 1.50, 95% CI: 0.94–2.40; OR = 1.27, 95% CI: 0.88–1.84). Individuals with ID and DD genotype of APOBEC3B had influence on susceptibility to acquisition of HIV‐1. This suggests that APOBEC3B deletion may attenuate innate cellular immunity against HIV‐1 and thus confer the host persistence for HIV infection.  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