全文获取类型
收费全文 | 629篇 |
免费 | 50篇 |
出版年
2021年 | 10篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 17篇 |
2014年 | 18篇 |
2013年 | 30篇 |
2012年 | 16篇 |
2011年 | 28篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 14篇 |
2003年 | 18篇 |
2002年 | 10篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 19篇 |
1981年 | 21篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 12篇 |
1972年 | 14篇 |
1970年 | 5篇 |
1968年 | 5篇 |
1951年 | 4篇 |
1938年 | 4篇 |
排序方式: 共有679条查询结果,搜索用时 31 毫秒
191.
Lujan TJ Lake SP Plaizier TA Ellis BJ Weiss JA 《Journal of biomechanical engineering》2005,127(1):193-197
The objective of this study was to assess the precision and accuracy of a nonproprietary, optical three-dimensional (3D) motion analysis system for the simultaneous measurement of soft tissue strains and joint kinematics. The system consisted of two high-resolution digital cameras and software for calculating the 3D coordinates of contrast markers. System precision was assessed by examining the variation in the coordinates of static markers over time. Three-dimensional strain measurement accuracy was assessed by moving contrast markers fixed distances in the field of view and calculating the error in predicted strain. Three-dimensional accuracy for kinematic measurements was assessed by simulating the measurements that are required for recording knee kinematics. The field of view (190 mm) was chosen to allow simultaneous recording of markers for soft tissue strain measurement and knee joint kinematics. Average system precision was between +/-0.004 mm and +/-0.035 mm, depending on marker size and camera angle. Absolute error in strain measurement varied from a minimum of +/-0.025% to a maximum of +/-0.142%, depending on the angle between cameras and the direction of strain with respect to the camera axes. Kinematic accuracy for translations was between +/-0.008 mm and +/-0.034 mm, while rotational accuracy was +/-0.082 deg to +/-0.160 deg. These results demonstrate that simultaneous optical measurement of 3D soft tissue strain and 3D joint kinematics can be performed while achieving excellent accuracy for both sets of measurements. 相似文献
192.
Rapid detection of Listeria monocytogenes in ham samples using immunomagnetic separation followed by polymerase chain reaction 总被引:4,自引:0,他引:4
Hudson JA Lake RJ Savill MG Scholes P McCormick RE 《Journal of applied microbiology》2001,90(4):614-621
AIMS: To develop a 24-h system for the detection of Listeria monocytogenes in ham. METHODS AND RESULTS: An immunomagnetic separation (IMS) of bacteria directly from ham followed by extraction of DNA and detection using a new multiplex polymerase chain reaction (PCR) was used. The PCR method used one primer pair targeted at the listeriolysin O gene of L. monocytogenes and the other pair for a region of the 23S rRNA genes of Listeria, giving products of 706 and 239 bp, respectively. The combined IMS/PCR was calculated to be capable of detecting as few as 1.1 L. monocytogenes cells g-1 in a 25-g ham sample. CONCLUSION: The process produced acceptable results, but the IMS step is the main barrier to further improvement of sensitivity. The DNA isolation was the most time-consuming step in the process. SIGNIFICANCE AND IMPACT OF THE STUDY: A 24-h test for the presence of L. monocytogenes will be useful to the food industry and significantly assist in the timely investigation of outbreaks. 相似文献
193.
Weetall M Hugo R Friedman C Maida S West S Wattanasin S Bouhel R Weitz-Schmidt G Lake P 《Analytical biochemistry》2001,293(2):277-287
We have developed a homogeneous high-capacity assay format for measuring integrin- and selectin-dependent cell binding to immobilized ligand using V-well microtiter plates. 2',7'-Bis(2-carboxyethyl)-5-(and-6)-carboxylfluorescence, acetoxymethylester-labeled cells are added to ligand-coated V-shaped microtiter wells. Bound cells are separated from free cells using centrifugal force to produce shear stress. Nonadherent cells accumulate in the nadir of the well and are measured using a fluorescence plate reader. Antibody or low-molecular-weight inhibitors of either the ligand or the cell surface receptor result in less cell binding, more cells in the pellet, and increased signal. The optimization and validation of the very late antigen-4/vascular cell adhesion molecule-1 assay is described in detail. We demonstrate that this assay can be rapidly adapted to measure other integrin- and selectin-mediated interactions. This assay format has several advantages over conventional assays. The centrifugal process is biologically relevant and eliminates the washing steps to remove nonadherent cells that can cause well-to-well and plate-to-plate variation. Because the assay is robust with a high signal-to-noise ratio and low variability, it is ideally suited for studying multiple parameters of cell adhesion and for high capacity screening. 相似文献
194.
195.
196.
197.
A technique for assessing the composition and density of the macroinvertebrate fauna of large stones in streams 总被引:7,自引:5,他引:2
A device for quantitatively sampling the macroinvertebrates of large stones in streams is described. In comparison to the usual method for sampling the fauna of large stones, (the lifting of stones upstream of a hand net), the present method accurately samples stonedwelling animals that are good swimmers. Details are given of a reliable method to measure the surface area of stream stones using thin plastic sheeting. 相似文献
198.
Improved Technique for the Isolation of Temperature-Sensitive Mutants of Foot-and-Mouth Disease Virus 总被引:4,自引:2,他引:2 下载免费PDF全文
An improved temperature-shift selection and screening method is described for the isolation of temperature-sensitive mutants of foot and mouth disease virus. 相似文献
199.
200.