全文获取类型
收费全文 | 20013篇 |
免费 | 1947篇 |
国内免费 | 1809篇 |
出版年
2024年 | 11篇 |
2023年 | 258篇 |
2022年 | 323篇 |
2021年 | 977篇 |
2020年 | 821篇 |
2019年 | 1012篇 |
2018年 | 935篇 |
2017年 | 652篇 |
2016年 | 905篇 |
2015年 | 1333篇 |
2014年 | 1481篇 |
2013年 | 1633篇 |
2012年 | 1945篇 |
2011年 | 1634篇 |
2010年 | 1046篇 |
2009年 | 984篇 |
2008年 | 1070篇 |
2007年 | 925篇 |
2006年 | 804篇 |
2005年 | 693篇 |
2004年 | 521篇 |
2003年 | 527篇 |
2002年 | 459篇 |
2001年 | 344篇 |
2000年 | 266篇 |
1999年 | 320篇 |
1998年 | 184篇 |
1997年 | 182篇 |
1996年 | 190篇 |
1995年 | 163篇 |
1994年 | 147篇 |
1993年 | 130篇 |
1992年 | 136篇 |
1991年 | 105篇 |
1990年 | 108篇 |
1989年 | 84篇 |
1988年 | 76篇 |
1987年 | 54篇 |
1986年 | 58篇 |
1985年 | 63篇 |
1984年 | 41篇 |
1983年 | 25篇 |
1982年 | 24篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Fluid-structural coupling occurs when microcantilever sensors vibrate in a fluid. Due to the complexity of the mechanical characteristics of microcantilevers and lack of high-precision microscopic mechanical testing instruments, effective methods for studying the fluid-structural coupling of microcantilevers are lacking, especially for non-rectangular microcantilevers. Here, we report fluid-structure interactions (FSI) of the cable-membrane structure via a macroscopic study. The simplified aeroelastic model was introduced into the microscopic field to establish a fluid-structure coupling vibration model for microcantilever sensors. We used the finite element method to solve the coupled FSI system. Based on the simplified aeroelastic model, simulation analysis of the effects of the air environment on the vibration of the commonly used rectangular microcantilever was also performed. The obtained results are consistent with the literature. The proposed model can also be applied to the auxiliary design of rectangular and non-rectangular sensors used in fluid environments. 相似文献
2.
Bayesian nonparametric inference for panel count data with an informative observation process 下载免费PDF全文
In this paper, the panel count data analysis for recurrent events is considered. Such analysis is useful for studying tumor or infection recurrences in both clinical trial and observational studies. A bivariate Gaussian Cox process model is proposed to jointly model the observation process and the recurrent event process. Bayesian nonparametric inference is proposed for simultaneously estimating regression parameters, bivariate frailty effects, and baseline intensity functions. Inference is done through Markov chain Monte Carlo, with fully developed computational techniques. Predictive inference is also discussed under the Bayesian setting. The proposed method is shown to be efficient via simulation studies. A clinical trial dataset on skin cancer patients is analyzed to illustrate the proposed approach. 相似文献
3.
4.
5.
In order to develop a multi-microbe probiotic preparation of Lactobacillus reuteri G8-5 and Bacillus subtilis MA139 in solid-state fermentation, a series of parameters were optimized sequentially in shake flask culture. The effect of supplementation of B. subtilis MA139 as starters on the viability of L. reuteri G8-5 was also explored. The results showed that the optimized process was as follows: water content, 50 %; initial pH of diluted molasses, 6.5; inocula volume, 2 %; flask dry contents, 30~35 g/250 g without sterilization; and fermentation time, 2 days. The multi-microbial preparations finally provided the maximum concentration of Lactobacillus of about 9.01?±?0.15 log CFU/g and spores of Bacillus of about 10.30?±?0.08 log CFU/g. Compared with pure fermentation of L. reuteri G8-5, significantly high viable cells, low value of pH, and reducing sugar in solid substrates were achieved in mixed fermentation in the presence of B. subtilis MA139 (P?<?0.05). Meanwhile, the mixed fermentation showed the significantly higher antimicrobial activity against E. coli K88 (P?<?0.05). Based on the overall results, the optimized process enhanced the production of multi-microbe probiotics in solid-state fermentation with low cost. Moreover, the viability of L. reuteri G8-5 could be significantly enhanced in the presence of B. subtilis MA139 in solid-state fermentation, which favored the production of probiotics for animal use. 相似文献
6.
7.
A case of chromomycosis in which hyperthermia proved effective is reported. The patient was a 56-year-old male bean curd maker who, without any previous history of minor trauma, developed on the extensor side of the left upper arm an eczematous lesion that underwent gradual radial expansion. The lesion showed a well-defined, 7×10 cm infiltrated erythematous plaque with the central area healed and, at the upper and lower borders, adherent scales and crusts on the surface. Histological examination revealed granulomatous changes in the dermis, as well as sclerotic cells within giant cells and microabscesses. On culturing,Fonsecaea pedrosoi was isolated. The patient was treated with disposable chemical pocket warmers, which were secured over the lesion with a rather tight elastic bandage, so that they kept the affected area warm for 24 hours a day. After a month of such hyperthermic treatment, the erythema and infiltration had decreased considerably, and microscopic examination and culture of the crusts both yielded negative results. Examination of biopsy specimens of the lesion after the third month showed that it had cicatrized. The treatment was stopped after 4 months, and no relapse occurred. We also summarize the published results of local hyperthermic treatment of chromomycosis in Japan. 相似文献
8.
Liu Minliang Liang Liang Liu Haofei Zhang Ming Martin Caitlin Sun Wei 《Biomechanics and modeling in mechanobiology》2019,18(2):387-398
Biomechanics and Modeling in Mechanobiology - It is well known that residual deformations/stresses alter the mechanical behavior of arteries, e.g., the pressure–diameter curves. In an effort... 相似文献
9.
Jiaming Liang Thibault Mesplède Maureen Oliveira Kaitlin Anstett Mark A. Wainberg 《Journal of virology》2015,89(22):11269-11274
10.