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   43848篇
  免费   3288篇
  国内免费   1308篇
耳鼻咽喉   115篇
儿科学   637篇
妇产科学   383篇
基础医学   5665篇
口腔科学   879篇
临床医学   3227篇
内科学   4869篇
皮肤病学   318篇
神经病学   4056篇
特种医学   1261篇
外国民族医学   3篇
外科学   1858篇
综合类   4009篇
现状与发展   2篇
一般理论   1篇
预防医学   4281篇
眼科学   258篇
药学   10880篇
  12篇
中国医学   3807篇
肿瘤学   1923篇
  2023年   617篇
  2022年   815篇
  2021年   1431篇
  2020年   1412篇
  2019年   1404篇
  2018年   1370篇
  2017年   1508篇
  2016年   1444篇
  2015年   1389篇
  2014年   2315篇
  2013年   3773篇
  2012年   2096篇
  2011年   2498篇
  2010年   1745篇
  2009年   2018篇
  2008年   1974篇
  2007年   1965篇
  2006年   1685篇
  2005年   1498篇
  2004年   1302篇
  2003年   1173篇
  2002年   1040篇
  2001年   975篇
  2000年   727篇
  1999年   708篇
  1998年   622篇
  1997年   563篇
  1996年   537篇
  1995年   662篇
  1994年   519篇
  1993年   487篇
  1992年   488篇
  1991年   446篇
  1990年   422篇
  1989年   420篇
  1988年   369篇
  1987年   366篇
  1986年   336篇
  1985年   460篇
  1984年   417篇
  1983年   291篇
  1982年   370篇
  1981年   285篇
  1980年   297篇
  1979年   216篇
  1978年   224篇
  1977年   168篇
  1976年   197篇
  1975年   84篇
  1974年   75篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In the present study, we have evaluated the antifungal activity of the seed, root and leaf of Paeonia emodi (commonly known as Himalayan peony) in four common solvents (acetone, chloroform, methanol and water) against six fungal strains. The methanolic seed extract (MSE) showed promising antifungal activity against Candida albicans (6.25 mg/mL), Candida glabrata (3.12 mg/mL) and Candida parapsilosis (12.50 mg/mL) among all the fungal strains tested. Combination of the MSE with the well-known commercial antifungal drugs amphotericin B (Amp B), nystatin (NYS) and fluconazole (FLC) resulted in the killing of C. glabrata at non-inhibitory concentrations, i.e., 0.35 μg/mL for Amp B, 0.55 μg/mL for NYS and 1.19 μg/mL for FLC. Notably, MSE caused cell wall damage of C. glabrata cells, as confirmed by confocal microscopy, flowcytometry and scanning electron microscopy (SEM). The MSE was fractionated by thin layer chromatography (TLC). TLC-bioautography was used to determine the active compounds present in the MSE. Column chromatography was used to separate the potential active compounds from the MSE. Furthermore, gas chromatography-mass spectrometry (GC-MS) andfourier-transform infrared spectroscopy (FTIR) were used to identify the phytocomponents of the MSE. These experiments revealed 13-docosenamide/9-octadecenamide/trans-13-docosenamide (89.70%) as being the predominant compound using a chloroform/methanol solvent system for the separation. Interestingly, the MSE also exhibited less significant cytotoxicity at the minimum inhibitory concentration (MIC) against mammalian cells (HeLa and HEK293). This study suggests that the MSE of P. emodi can be used for the treatment of C. glabrata infection.  相似文献   
992.
《Research in microbiology》2016,167(8):647-654
Haemophilus parainfluenzae and Haemophilus influenzae, upper respiratory tract microbiota representatives, are able to colonize natural and artificial surfaces as biofilm. The aim of the present study was to assay the effect of ten 1,2,4-triazole-ciprofloxacin hybrids on planktonic or biofilm-forming haemophili cells in vitro under stationary conditions on the basis of MICs (minimal inhibitory concentrations) and MBICs (minimal biofilm inhibitory concentrations). In addition, anti-adhesive properties of these compounds were examined. The reference strains of H. parainfluenzae and H. influenzae were included. The broth microdilution microtiter plate (MTP) method with twofold dilution of the compounds, or ciprofloxacin (reference agent) in 96-well polystyrene microplates, was used. The optical density (OD) reading was made spectrophotometrically at a wavelength of 570 nm (OD570) both to measure bacterial growth and to detect biofilm-forming cells under the same conditions with 0.1% crystal violet. The following values of parameters were estimated for 1,2,4-triazole-ciprofloxacin hybrids – MIC = 0.03–15.63 mg/L, MBIC = 0.03–15.63 mg/L, MBIC/MIC = 0.125–8, depending on the compound, and for ciprofloxacin – MIC = 0.03–0.06 mg/L, MBIC = 0.03–0.12 mg/L, MBIC/MIC = 1–2. The observed strong anti-adhesive properties (95–100% inhibition) of the tested compounds were reversible during long-term incubation at subinhibitory concentrations.Thus, 1,2,4-triazole-ciprofloxacin hybrids may be considered as starting compounds for designing improved agents not only against planktonic but also against biofilm-forming Haemophilus spp. cells.  相似文献   
993.
Physical activity (PA) is a part of a healthy pregnancy. To date, no consumer-based activity monitors have been validated with this population. The aim of this study was to validate the Fitbit Zip and Fitbit Flex monitors in free-living conditions with pregnant women using the ActiGraph GT3X as the ?gold standard?. We compared the accuracy of the Fitbit Zip and Fitbit Flex devices in measuring steps, sedentary time and time spent in different activity intensities. Sixteen women in their third trimester of pregnancy wore the ActiGraph GT3X (hip) plus one Fibit Zip (hip) and one Fitbit Flex (wrist) during seven consecutive days. The validity of Fitbit Zip and Fitbit Flex is good, depending on measured parameters. Fitbit Zip is accurate to measure steps whereas Fitbit Flex is precise for MVPA. When choosing between Fitbit Zip and Fitbit Flex monitors, pregnant women should take into account their preferred PA and the parameters they want to measure..  相似文献   
994.
To evaluate the impact of pedometer use on the physical activity (PA) and functional walking capacity (FWC) of adolescents with juvenile idiopathic arthritis (JIA) and lower extremity (LE) involvement. Twenty-seven adolescents, aged 11–19 years with JIA and LE involvement, participated in the three-phase pedometer study that introduced the use of a pedometer and an education seminar at 6 weeks. Measurements were taken at the baseline first visit and at weeks 6, 12, and 20. The primary outcome measure was the 6-minute walk test (6MWT). Thirteen completed the study. Six-minute walk distance (6MWD) significantly increased from baseline (458.0 ± 70.8 m) to the end of phase 1 (501.4 ± 59.8 m) (p = 0.035), prior to receiving the pedometer; and from baseline to the end of study (p = 0.0037). No significant changes in 6MWD were found between weeks 6 and 12 (intervention) (p = 0.77) or between weeks 12 and 20 (follow through phase) (p = 0.27). In adolescents with LE JIA, consistent guidance and support by rheumatology professionals appears to positively influence PA and measures of FWC as seen through improved 6MWD. There was insufficient evidence to show that pedometers further increased FWC or PA.  相似文献   
995.
996.
997.
Recently, the Surgeon General put out a Call to Action “To Promote Walking and Walkable Communities.” Walking is a powerful health promotion activity that nurse practitioners (NPs) can quickly prescribe as part of a management plan for the vast majority of their patients. NPs are key health care professionals in the promotion of walking and other physical activity for their patients across the life span. NPs should be familiar with physical activity recommendations for all of their patients, including patients with disabilities. NPs need to be able to assess physical activity as well as prescribe individualized physical activity plans.  相似文献   
998.
999.
Phytochemical investigation of the ethanol extract from the twigs and leaves of Croton tiglium led to the isolation of two new phorbol esters (1–2) and seven known ones (3–9). Their structures were elucidated by the analyses of extensive spectroscopic data (IR, MS, and 1D and 2D NMR) and comparing with related compounds. Meanwhile, compounds 1–9 were determined for their cytotoxic activities on human lung cancer cell line A549. Among them, 1–2 were inactive against the cell line A549 (IC50 > 100 μM), but compounds 3 and 7 showed weak activities.  相似文献   
1000.
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