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   283919篇
  免费   3517篇
  国内免费   1014篇
化学   156995篇
晶体学   3114篇
力学   11834篇
综合类   9篇
数学   28816篇
物理学   87682篇
  2016年   3340篇
  2015年   2511篇
  2014年   3511篇
  2013年   11799篇
  2012年   7946篇
  2011年   10044篇
  2010年   6547篇
  2009年   6349篇
  2008年   9128篇
  2007年   9266篇
  2006年   9037篇
  2005年   8487篇
  2004年   7512篇
  2003年   6692篇
  2002年   6049篇
  2001年   7962篇
  2000年   5891篇
  1999年   4636篇
  1998年   3640篇
  1997年   3869篇
  1996年   3722篇
  1995年   3774篇
  1994年   3489篇
  1993年   3296篇
  1992年   4016篇
  1991年   3804篇
  1990年   3693篇
  1989年   3728篇
  1988年   3713篇
  1987年   3711篇
  1986年   3463篇
  1985年   4800篇
  1984年   4921篇
  1983年   4044篇
  1982年   4453篇
  1981年   4292篇
  1980年   4215篇
  1979年   4395篇
  1978年   4729篇
  1977年   4467篇
  1976年   4479篇
  1975年   4249篇
  1974年   4111篇
  1973年   4333篇
  1972年   2726篇
  1971年   2218篇
  1969年   2152篇
  1968年   2756篇
  1967年   3010篇
  1966年   2586篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Pomogaev  V. A.  Lee  H. J.  Goh  E.  Tchaikovskaya  O. N.  Kononov  A. I.  Avramov  P. V. 《Russian Physics Journal》2022,64(11):2076-2081
Russian Physics Journal - Theoretical calculations of excited states in the complexes of gold and silver three-atom nanoclusters with carbon quantum nanodots are performed using the M062X...  相似文献   
2.
Annals of Operations Research - In recent years, operations research in agriculture has improved the harvested yield, reduced the cost and time required for field operations, and maintained...  相似文献   
3.
Mathematical Programming - Scenario generation is the construction of a discrete random vector to represent parameters of uncertain values in a stochastic program. Most approaches to scenario...  相似文献   
4.
Statistical Inference for Stochastic Processes - The class of autoregressive (AR) processes is extensively used to model temporal dependence in observed time series. Such models are easily...  相似文献   
5.
Annals of Operations Research - Selecting a vegetation layer design goes along with determining its future irrigation need. Therefore, it is essential to take a design decision that is minimising...  相似文献   
6.
Atopic dermatitis is characterized by leukocyte migration into the skin dermis and typically driven by excessive chemokine production at the site of inflammation. Conventional topical formulations such as gels, creams, and ointments are insufficient for this treatment because of low penetration of drug molecules into the targeted skin tissues. Herein, using a simple, green, sustainable strategy, we have developed novel primary zein nanoparticles embedded in curcumin (Cur) and coated with silk sericin (ZHSCs) for the topical delivery of Cur to penetrate into the dermis and exercise anti-dermatitis effects on the lesion with minimal side-effects. Transdermal delivery experiments and porcine skin fluorescence imaging indicated that ZHSCs facilitate the penetration of Cur across the epidermis layer of skin to reach deep-seated sites. Notably, ZHSCs = 1:0.25 (zein-to-silk sericin mass ratios of 1:0.25) markedly elevated the skin permeability and cumulative turnover of Cur transferred, which were provided a greater than a 3.8-fold increase relative to free Cur. The special nanoparticles of ZHS = 1:0.25 possessed the deepest localization depth and experience a transition of the particle structure and core-shell separation after penetrating into the dermis of skin. In a cell model of dermatitis induced by tumor necrosis factor α/interferon γ co-stimulation, compared with free Cur, Cur-loaded ZHS nanoparticles down-regulated the generation of inflammatory cytokines and chemokines in keratinocytes through suppression of the nuclear translocation of NF-κBp65 and hence exerted an anti-dermatitis effect. This strategy may provide new avenues and direction for the demanding issues of valid topical delivery systems.  相似文献   
7.
Journal of Applied Spectroscopy - The aromaticity in the lowest triplet T1-state of NH-tautomers of corrole free bases with different peripheral substitution architecture was investigated using...  相似文献   
8.
Applied Mathematics and Mechanics - Mechanical models of residually stressed fibre-reinforced solids, which do not resist bending, have been developed in the literature. However, in some residually...  相似文献   
9.
Journal of Analytical Chemistry - The review considers the historical aspects of the formation and development of bioelectrochemistry and some issues of the analytical application of...  相似文献   
10.
Ultrasound has been recognized as an exciting tool to enhance the therapeutic efficacy in tumor chemotherapy owing to the triggered drug release, facilitated intracellular drug delivery, and improved spatial precision. Aiming for a precise localized drug delivery, novel dendritic polyurethane-based prodrug (DOX-DPU-PEG) was fabricated with a drug content of 18.9% here by conjugating DOX onto the end groups of the functionalized dendritic polyurethane via acid-labile imine bonds. It could easily form unimolecular micelles around 38 nm. Compared with the non-covalently drug-loaded unimolecular micelles (DOX@Ph-DPU-PEG), they showed excellent pH/ultrasound dual-triggered drug release performance, with drug leakage of only 4% at pH 7.4, but cumulative release of 14% and 88% at pH 5.0 without and with ultrasound, respectively. The ultrasound responsiveness was attributed to the unique strawberry-shaped topological structure of the DOX-DPU-PEG, in which DOX was embedded in the skin layer of the hydrophobic DPU cores. With ultrasound, the DOX-DPU-PEG unimolecular micelles possessed enhanced tumor growth inhibition than free DOX but showed no obvious cytotoxicity on the tumor cells without ultrasound. Such feature makes them promising potential for precise localized drug delivery.  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