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   6271篇
  免费   276篇
  国内免费   32篇
耳鼻咽喉   137篇
儿科学   161篇
妇产科学   143篇
基础医学   656篇
口腔科学   484篇
临床医学   331篇
内科学   1733篇
皮肤病学   114篇
神经病学   460篇
特种医学   118篇
外科学   846篇
综合类   18篇
一般理论   1篇
预防医学   540篇
眼科学   184篇
药学   297篇
中国医学   15篇
肿瘤学   341篇
  2024年   9篇
  2023年   63篇
  2022年   135篇
  2021年   242篇
  2020年   121篇
  2019年   145篇
  2018年   207篇
  2017年   153篇
  2016年   168篇
  2015年   199篇
  2014年   293篇
  2013年   319篇
  2012年   541篇
  2011年   530篇
  2010年   262篇
  2009年   225篇
  2008年   394篇
  2007年   428篇
  2006年   375篇
  2005年   326篇
  2004年   305篇
  2003年   264篇
  2002年   228篇
  2001年   47篇
  2000年   45篇
  1999年   48篇
  1998年   29篇
  1997年   27篇
  1996年   22篇
  1995年   22篇
  1994年   28篇
  1993年   15篇
  1992年   33篇
  1991年   35篇
  1990年   38篇
  1989年   42篇
  1988年   22篇
  1987年   19篇
  1986年   21篇
  1985年   17篇
  1984年   16篇
  1983年   8篇
  1982年   13篇
  1981年   13篇
  1980年   11篇
  1979年   6篇
  1977年   11篇
  1976年   8篇
  1975年   6篇
  1971年   5篇
排序方式: 共有6579条查询结果,搜索用时 15 毫秒
61.
62.
63.
Digestive Diseases and Sciences - Mesenteric cysts are defined as a heterogeneous group of intra-abdominal cystic lesions of the mesentery or omentum that may be found in any portion of the...  相似文献   
64.
Protein–protein interactions are key in virtually all biological processes. The study of these interactions and the interfaces that mediate them play a key role in the understanding of biological function. In particular, the observation of protein–protein interactions in their dynamic environment is technically difficult. Here two surface analysis techniques, dual polarization interferometry and quartz crystal microbalance with dissipation monitoring, were paired for real-time mapping of the conformational dynamics of protein–protein interactions. Our approach monitors this dynamics in real time and in situ, which is a great advancement within technological platforms for drug discovery. Results agree with the experimental observations of the interaction between the TRIM21α protein and circulating autoantibodies via a bridging bipolar mechanism. This work provides a new chip-based method to monitor conformational dynamics of protein–protein interactions, which is amenable to miniaturized high-throughput determination.

Protein–protein interactions are key in virtually all biological processes.  相似文献   
65.
The aims of this pilot study were to verify which muscle strength tests better explain bone mineral content (BMC) of the femoral neck and lumbar spine and to develop predictive equations to estimate femoral neck and lumbar spine BMC. Twenty-nine subjects aged 56–76 years old (12 women and 17 men) participated in the study. Femoral neck and lumbar spine BMC was evaluated by Dual X-ray absorptiometry (DXA). Muscle strength measurements included maximal isometric voluntary contractions of knee extensors and flexors, vertical jump, 5-repetition maximum of the leg press (5-RMLP) and seated leg curl (5-RMLC), and handgrip strength. Women presented a moderate to strong correlation between femoral neck BMC and 5-RMLP (r = 0.819), 5-RMLC (r = 0.879), knee extensors peak torque (r = 0.699), and handgrip strength (r = 0.663), as well as between lumbar spine BMC and the 5-RMLP test (r = 0.845) and manual grip strength (r = 0.699). For females, the 5-RMLP and 5-RMLC tests most fully explained femoral neck BMC (R2 = 0.859) and the 5-RMLP test and body mass explained lumbar spine density (R2 = 0.757) for females. Men did not present correlations between BMC and strength variables. For females, the 5-RMLP and 5-RMLC variables explained the variations of femoral neck BMC, while 5-RMLP and body mass explained lumbar spine BMC. Future studies should evaluate a larger sample size and prioritize the strength tests with a greater predictive capacity.  相似文献   
66.
Kinesio Taping® elastic tape is increasingly used in physiotherapy treatment. However, there is a lack of scientific research regarding the late effects of its use. This study quantified the late effects of applying the Kinesio Taping® elastic tape by measuring changes in handgrip muscle strength after 24, 48 and 72 h of application. The Kinesio Taping® elastic tape was applied on the dominant and non-dominant limbs of 36 volunteers randomly assigned to three groups: muscle facilitation, muscle inhibition and control group. The statistical test showed there was a statistically significant difference among all groups of dominant limb and non-dominant limb. However, the analysis on intragroup relationship to periods of application (Initial, 24, 48 and 72 h) and the interaction among repeated measures showed there was no statistically significant difference. This result may contribute to the investigation of the late effects of the Kinesio Taping® elastic tape on the physical rehabilitation.  相似文献   
67.
In the present work, we describe the preparation of ten amino acid ionic liquids (AAILs) formed from ammonium salts as cations, derivatives of glycerol, and natural amino acids as anions. All of them are viscous oils, colorless or pale yellow, and hygroscopic at room temperature. They have appreciable solubility in many protic and aprotic polar solvents. The AAILs were used as catalysts in a Morita–Baylis–Hillman (MBH) reaction. The ionic liquids derivative from l-proline and l-histidine demonstrated the ability to catalyze the reaction between methyl vinyl ketone and aromatic aldehydes differently substituted in the absence of an additional co-catalyst under organic solvent-free conditions. The AAIL derivatives from l-valine, l-leucine, and l-tyrosine catalyzed the MBH reaction only in the presence of imidazole. The MBH adducts were obtained in moderate to good yields. Although the catalytic site in the ILs was in its enantiomerically pure form, all the MBH adducts were obtained in their racemic form.

In this work, we describe the preparation of ten amino acid ionic liquids (AAILs). The AAILs were used as catalysts in a Morita–Baylis–Hillman (MBH) reaction. The MBH adducts were obtained from moderate to good yields and in their racemic form.  相似文献   
68.
Because swine influenza virus infection is seldom diagnosed in humans, its frequency might be underestimated. We report a immunocompromised hematologic patient with swine influenza A(H3N2) virus in 2014 in Italy. Local pigs were the source of this human infection.  相似文献   
69.
70.
Cyclospora cayetanensis is an emerging protozoan parasite capable of causing a protracted diarrheal illness in both immunocompromised and immunocompetent individuals. Ingestion of fresh produce and water sources contaminated with mature sporulated oocysts results in acquisition of cyclosporiasis. Currently, no animal model exists for the study of this pathogenic parasite and the only confirmed reservoir host for C. cayetanensis in nature is humans. Previously, Cyclospora-like oocysts had been detected by microscopy in several animals including non-human primates. However, their phylogenetic relationship to C. cayetanensis remained uncertain due to the limited availability of molecular techniques to differentiate and speciate these isolates. In the present study, we examined a series of fecal isolates obtained from dogs, chickens, and monkeys collected between May and September 2002 from several geographic regions of Nepal. All samples were examined by microscopy and a polymerase chain reaction (PCR) for the presence of C. cayetanensis. Both microscopic and conventional PCR/restriction fragment length polymorphism (RFLP) analysis demonstrated the presence of Cyclospora sp. in the fecal samples of two dogs, one chicken, and one monkey. Application of a species-specific multiplex PCR assay confirmed the presence of both Eimeria sp. and C. cayetanensis in the positive chicken sample and only C. cayetanensis in the dog and monkey samples. However, in the absence of tissue analysis, the assignment of these animals as a natural reservoir host for C. cayetanensis remains to be determined.  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