全文获取类型
收费全文 | 11444篇 |
免费 | 938篇 |
国内免费 | 635篇 |
学科分类
工业技术 | 13017篇 |
出版年
2024年 | 54篇 |
2023年 | 190篇 |
2022年 | 290篇 |
2021年 | 338篇 |
2020年 | 416篇 |
2019年 | 324篇 |
2018年 | 332篇 |
2017年 | 382篇 |
2016年 | 400篇 |
2015年 | 449篇 |
2014年 | 673篇 |
2013年 | 839篇 |
2012年 | 728篇 |
2011年 | 799篇 |
2010年 | 552篇 |
2009年 | 632篇 |
2008年 | 575篇 |
2007年 | 764篇 |
2006年 | 693篇 |
2005年 | 546篇 |
2004年 | 459篇 |
2003年 | 396篇 |
2002年 | 348篇 |
2001年 | 299篇 |
2000年 | 247篇 |
1999年 | 197篇 |
1998年 | 213篇 |
1997年 | 181篇 |
1996年 | 150篇 |
1995年 | 116篇 |
1994年 | 98篇 |
1993年 | 60篇 |
1992年 | 64篇 |
1991年 | 45篇 |
1990年 | 38篇 |
1989年 | 25篇 |
1988年 | 24篇 |
1987年 | 14篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1959年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
141.
采用种子乳液聚合方法制备了阴、阳离子型氟改性硅丙乳液,用红外光谱对聚合物进行了表征,考察了聚合温度、氟改性单体和种子乳液的用量、乳化剂用量和pH值等因素对转化率和聚合物膜与水之间接触角的影响。结果表明,该聚合物中含有聚硅氧烷链段和CF2基团;聚合温度对转化率的影响较显著;在阳离子乳化体系中,当聚硅氧烷种子乳液、含氟丙烯酸酯单体和乳化剂的用量分别为10%、10%和1.1%时,转化率可以达到90%左右,接触角达到104°以上;随着体系pH值的逐渐增大,阳离子型氟改性硅丙乳液的Zeta电位明显降低,但阴离子型乳液的Zeta电位变化较小。 相似文献
142.
采用颗粒离散元法建立了碎屑流三维数值模型,分别从整体和局部对碎屑流运动特性进行深入分析。结果表明:碎屑流的运动过程可分为启动加速、高速滑动和减速堆积3个阶段;边坡底面平整时,堆积体中大颗粒堆积在表面,而细小颗粒位于中下部位;碎屑流运动速度和能量损失受颗粒间的接触碰撞影响大;碎屑流不同部位运动速度最大值相同,达到速度峰值的时间与颗粒的初始水平位置有关,与深度无关;堆积体分区明显,堆积体中的颗粒按初始水平位置依次排布;坡脚位置堆积深度最大,往两侧逐渐减小;碎屑流在运动初期和末期横向运动明显,扩大了灾害影响范围。 相似文献
143.
144.
145.
Interactive rigid body simulation is an important part of many modern computer tools, which no authoring tool nor game engine can do without. Such high‐performance computer tools open up new possibilities for changing how designers, engineers, modelers and animators work with their design problems. This paper is a self contained state‐of‐the‐art report on the physics, the models, the numerical methods and the algorithms used in interactive rigid body simulation all of which have evolved and matured over the past 20 years. Furthermore, the paper communicates the mathematical and theoretical details in a pedagogical manner. This paper is not only a stake in the sand on what has been done, it also seeks to give the reader deeper insights to help guide their future research. 相似文献
146.
酸化水解-活性污泥-生物接触氧化工艺处理有机污水 总被引:2,自引:0,他引:2
介绍了采用酸化水解——活性污泥——生物接触氧化工艺处理含有山梨醇、甘露醇、蔗糖、醋酸乙烯、甲基纤维素的有机污水。该工艺具有出水水质稳定,操作简单、管理方便,能耗低等优点,是处理该类有机污水的有效方法。 相似文献
147.
Joon‐Seop Kim Min‐Chul Hong Yeon Hwa Nah Yeonhee Lee Seunghee Han Hyun Eui Lim 《应用聚合物科学杂志》2002,83(11):2500-2504
The wetting properties of polystyrene‐based ionomers treated with plasma source ion implantation (PSII) were investigated by the measurement of water contact angles. When sulfonated ionomers were aged for a few days, the hydrophobic recovery for the ionomers became much slower than that for the nonionic polymers. However, when the samples were aged over 20 days, the water contact angle of the ionomers converged with that of the nonionic polymer. Thus, it was concluded that the ionic interaction between the ionic groups and the presence of ionic groups together resulted in the slow hydrophobic recovery and that the aging effect was significant for the ionomers. For the methacrylate ionomer of low ion content, on the other hand, it was found that the PSII treatment produced only a small change in hydrophobic recovery behavior. Thus, it was suggested that the low ionic content coupled with the small size of the ionic unit might cause changes only of a very insignificant degree in hydrophobic recovery behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2500–2504, 2002 相似文献
148.
In the field of biomaterials and biomedical devices, surface activation has been focused on creating functional groups capable of preferential adsorption of biologically active species (proteins, enzymes, cells, drugs, etc.). In this way an interface can be created between the synthetic material and the biological medium, with the aim of increasing the compatibility of the implant with the human organism. In our experiments a dielectric barrier discharge (DBD), in helium at atmospheric pressure, was used as the source of energy capable of creating active centers that render the functionalized surface favorable to immobilization of biological molecules. Retention of immunoglobulin (IgG) and heparin biomolecules on polyamide‐6 (PA‐6) surfaces after treatment by the DBD was analyzed by atomic force microscopy, adhesion evaluation, and measurement of the contact angle titration in order to assess this incorporation on the treated surfaces. The marked adsorption of the biomolecules on the active sites created by DBD on the exposed surfaces also was related to a complex set of processes, such as enhanced roughness, increased surface wettability, and modified distribution of cationic and anionic groups on the treated surfaces. All these factors could promote interfacial interactions between the specific groups of the biomolecules existing in the biological medium and the type of cationic and/or anionic groups present on the surface. The efficiency of the DBD treatment showed that the DBD technique is useful for preactivation of the polymer surface for immobilization of other biologically active species (such as drugs and enzymes). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1985–1990, 2003 相似文献
149.
150.
Bhuvanesh Gupta Jns Hilborn Christopher Plummer Isabelle Bisson Peter Frey 《应用聚合物科学杂志》2002,85(9):1874-1880
Graft polymerization of acrylic acid onto plasma‐treated poly(ethylene terephthalate) (PET) films was used to prepare surfaces suitable for collagen immobilization by dip‐coating. Such surfaces could be used as matrices for smooth muscle cell cultures in tissue engineering. Contact angle measurements showed that plasma‐treated and grafted PET films undergo considerable surface reorganization during storage under ambient conditions. However, after collagen immobilization the contact angle remained relatively stable. The amount of collagen initially attached to the film surface increased with increasing poly(acrylic acid) graft density, but subsequent washing in water led to significant collagen loss. This loss could nevertheless be substantially reduced by thermal crosslinking of the collagen in the range 110–130 °C. Atomic force microscopy (AFM) observations suggested that the washed crosslinked collagen has a very similar structure to that of the un‐crosslinked collagen. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1874–1880, 2002 相似文献