全文获取类型
收费全文 | 335733篇 |
免费 | 30440篇 |
国内免费 | 558篇 |
出版年
2018年 | 8615篇 |
2017年 | 8387篇 |
2016年 | 7354篇 |
2015年 | 4830篇 |
2014年 | 5191篇 |
2013年 | 7750篇 |
2012年 | 10725篇 |
2011年 | 15747篇 |
2010年 | 11647篇 |
2009年 | 11013篇 |
2008年 | 13389篇 |
2007年 | 15068篇 |
2006年 | 7436篇 |
2005年 | 8256篇 |
2004年 | 7636篇 |
2003年 | 7652篇 |
2002年 | 7312篇 |
2001年 | 11926篇 |
2000年 | 12025篇 |
1999年 | 9334篇 |
1998年 | 3322篇 |
1997年 | 3561篇 |
1996年 | 3463篇 |
1995年 | 3149篇 |
1994年 | 3134篇 |
1993年 | 3145篇 |
1992年 | 7919篇 |
1991年 | 7902篇 |
1990年 | 7526篇 |
1989年 | 7503篇 |
1988年 | 6872篇 |
1987年 | 6624篇 |
1986年 | 6027篇 |
1985年 | 6212篇 |
1984年 | 5162篇 |
1983年 | 4370篇 |
1982年 | 3395篇 |
1981年 | 3149篇 |
1980年 | 2948篇 |
1979年 | 4948篇 |
1978年 | 3814篇 |
1977年 | 3723篇 |
1976年 | 3434篇 |
1975年 | 3797篇 |
1974年 | 4175篇 |
1973年 | 4095篇 |
1972年 | 4208篇 |
1971年 | 3904篇 |
1970年 | 3089篇 |
1969年 | 2995篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Bong Jin Kim Kyung Seob Song Hyun-Hee Kong Hee-Jae Cha Meesun Ock 《The Korean journal of parasitology》2014,52(1):85-87
We encountered a patient with heavy Hymenolepis nana infection. The patient was a 44-year-old Korean man who had suffered from chronic hepatitis (type B) for 15 years. A large number of H. nana adult worms were found during colonoscopy that was performed as a part of routine health screening. The parasites were scattered throughout the colon, as well as in the terminal ileum, although the patient was immunocompetent. Based on this study, colonoscopy may be helpful for diagnosis of asymptomatic H. nana infections. 相似文献
3.
E. Azizi A. R. Deslauriers N. C. Holt C. E. Eaton 《Biomechanics and modeling in mechanobiology》2017,16(5):1633-1643
The collagenous extracellular matrix (ECM) of skeletal muscle functions to transmit force, protect sensitive structures, and generate passive tension to resist stretch. The mechanical properties of the ECM change with age, atrophy, and neuromuscular pathologies, resulting in an increase in the relative amount of collagen and an increase in stiffness. Although numerous studies have focused on the effect of muscle fibrosis on passive muscle stiffness, few have examined how these structural changes may compromise contractile performance. Here we combine a mathematical model and experimental manipulations to examine how changes in the mechanical properties of the ECM constrain the ability of muscle fibers and fascicles to radially expand and how such a constraint may limit active muscle shortening. We model the mechanical interaction between a contracting muscle and the ECM using a constant volume, pressurized, fiber-wound cylinder. Our model shows that as the proportion of a muscle cross section made up of ECM increases, the muscle’s ability to expand radially is compromised, which in turn restricts muscle shortening. In our experiments, we use a physical constraint placed around the muscle to restrict radial expansion during a contraction. Our experimental results are consistent with model predictions and show that muscles restricted from radial expansion undergo less shortening and generate less mechanical work under identical loads and stimulation conditions. This work highlights the intimate mechanical interaction between contractile and connective tissue structures within skeletal muscle and shows how a deviation from a healthy, well-tuned relationship can compromise performance. 相似文献
4.
5.
6.
I. S. Voroshilova 《Biology Bulletin》2016,43(10):1301-1307
This review summarizes published data on the genetic markers used in studies of dreissenide invasions. Causes of genetic differences between local populations are discussed. It is shown that information about the genetic diversity of populations obtained by marker polymorphism analysis should be compared to study invasion directions. 相似文献
7.
N. Cappetti A. Naddeo G. F. Solitro 《Computer methods in biomechanics and biomedical engineering》2016,19(12):1278-1285
The aim of this work is to show a quick and simple procedure able to identify the geometrical parameters of the intervertebral disc that strongly affect the behavior of the FEM model. First, we allocated a selection criterion for the minimum number of geometrical parameters that describe, with a good degree of approximation, a healthy human vertebra. Next, we carried out a sensitivity analysis using the ‘Taguchi orthogonal array’ to arrive at a quick identification of the parameters that strongly affect the behavior of the Fem model. 相似文献
8.
Joyce S. F. D. de Almeida Teobaldo R. Cuya Guizado Ana P. Guimarães Teodorico C. Ramalho Arlan S. Gonçalves Martijn C. de Koning 《Journal of biomolecular structure & dynamics》2016,34(12):2632-2642
In the present work, we performed docking and molecular dynamics simulations studies on two groups of long-tailored oximes designed as peripheral site binders of acetylcholinesterase (AChE) and potential penetrators on the blood brain barrier. Our studies permitted to determine how the tails anchor in the peripheral site of sarin-inhibited human AChE, and which aminoacids are important to their stabilization. Also the energy values obtained in the docking studies corroborated quite well with the experimental results obtained before for these oximes. 相似文献
9.
10.