全文获取类型
收费全文 | 65409篇 |
免费 | 4822篇 |
国内免费 | 2857篇 |
专业分类
电工技术 | 5816篇 |
技术理论 | 3篇 |
综合类 | 6627篇 |
化学工业 | 7963篇 |
金属工艺 | 3149篇 |
机械仪表 | 2872篇 |
建筑科学 | 9197篇 |
矿业工程 | 3328篇 |
能源动力 | 4087篇 |
轻工业 | 3881篇 |
水利工程 | 2845篇 |
石油天然气 | 6400篇 |
武器工业 | 255篇 |
无线电 | 2899篇 |
一般工业技术 | 4273篇 |
冶金工业 | 3676篇 |
原子能技术 | 880篇 |
自动化技术 | 4937篇 |
出版年
2024年 | 175篇 |
2023年 | 738篇 |
2022年 | 1408篇 |
2021年 | 1840篇 |
2020年 | 1707篇 |
2019年 | 1413篇 |
2018年 | 1213篇 |
2017年 | 1489篇 |
2016年 | 1785篇 |
2015年 | 2023篇 |
2014年 | 3964篇 |
2013年 | 3429篇 |
2012年 | 4625篇 |
2011年 | 4861篇 |
2010年 | 3763篇 |
2009年 | 3898篇 |
2008年 | 3420篇 |
2007年 | 4583篇 |
2006年 | 4199篇 |
2005年 | 3727篇 |
2004年 | 3143篇 |
2003年 | 2820篇 |
2002年 | 2414篇 |
2001年 | 1977篇 |
2000年 | 1678篇 |
1999年 | 1303篇 |
1998年 | 944篇 |
1997年 | 773篇 |
1996年 | 683篇 |
1995年 | 609篇 |
1994年 | 473篇 |
1993年 | 362篇 |
1992年 | 288篇 |
1991年 | 194篇 |
1990年 | 201篇 |
1989年 | 189篇 |
1988年 | 139篇 |
1987年 | 107篇 |
1986年 | 71篇 |
1985年 | 69篇 |
1984年 | 55篇 |
1983年 | 26篇 |
1982年 | 30篇 |
1981年 | 39篇 |
1980年 | 38篇 |
1979年 | 33篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1976年 | 18篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Recent advances in gene technology have helped to identify novel proteins and allowed study of their distribution and functions in the mammalian brain. One class of these proteins is that of transporters, which exist in plasma and organellar membranes of neurons and other cells to move substances selectively across membranes. These transporters can be categorized further into subclasses by their structural property, substrate selectivity, and site of action. Some of them have been identified in the hypothalamus, which is the only brain site where a neural signal is converted to a humoral one, namely, a hormone for a target organ. This unique neural mechanism has long attracted attention as the neuroendocrine system, part of which has been extensively studied as the hypothalamic-neurohypophysial system involved in secretion of vasopressin and oxytocin. However, transporters in this system have been less well studied. A morphological examination of novel transporters would give us cues to a better understanding of the neuronal organization and function of the system. In this review, we first summarize recent findings on expression of transporter gene and immunoreactivity in the hypothalamus. In the second part, we explain our observations on two vesicular glutamate (inorganic phosphate) transporters (BNPI and DNPI) in the supraoptic and paraventricular nuclei and neurohypophysis. Further study of these and other transporters will provide a basis on which to reevaluate the organization and function of the hypothalamic-neurohypophysial system. 相似文献
83.
ABSTRACT: :
Soybeans ( Glycine max ) were soaked and ground to obtain soymilk. The soymilk was cooked in an open tank and held at 85 to 90 deg;C. Yuba films were picked up in 20 min intervals and dried for 20 min. Yuba films were soaked in chicken-flavor solutions (25% and 35%), and baking soda (BS) solutions (0%, 1%, 2%, and 3% BS), and cooked at 100 °C for 30 min, 60 min, and 90 min. TIA decreased (p < 0.05) with the increase of heating time and BS concentration. In vitro protein digestibility (IVPD) decreased with heating time and BS concentration (p < 0.05). Sensory characteristics were affected by flavor concentration. By using 0% BS, 25% of the chicken flavor concentration, and a short heating time method, meat-like products with low TIA, high IVPD, and good sensory characteristics were obtained. 相似文献
Soybeans ( Glycine max ) were soaked and ground to obtain soymilk. The soymilk was cooked in an open tank and held at 85 to 90 deg;C. Yuba films were picked up in 20 min intervals and dried for 20 min. Yuba films were soaked in chicken-flavor solutions (25% and 35%), and baking soda (BS) solutions (0%, 1%, 2%, and 3% BS), and cooked at 100 °C for 30 min, 60 min, and 90 min. TIA decreased (p < 0.05) with the increase of heating time and BS concentration. In vitro protein digestibility (IVPD) decreased with heating time and BS concentration (p < 0.05). Sensory characteristics were affected by flavor concentration. By using 0% BS, 25% of the chicken flavor concentration, and a short heating time method, meat-like products with low TIA, high IVPD, and good sensory characteristics were obtained. 相似文献
84.
从控制PVC异型材挤出机的工艺参数的角度,分析并论述了挤出机工艺参数对PVC异型材低温落锤性能的影响。 相似文献
85.
浅谈冲压模具的维修要领及常见故障的排除 总被引:1,自引:0,他引:1
介绍冲压模具修理和检查各环节的主要工作内容及维修要领 ,列举了常见故障的排除方法 ,通过总结实际生产中的修模经验 ,对缩短修模周期 ,降低成本 ,延长模具寿命有一定的参考价值。。 相似文献
86.
用快切装置替代备自投装置提高厂用电安全可靠性 总被引:3,自引:0,他引:3
指出目前厂用电切换装置存在的不足,分析了快切装置的基本原理以及厂用电事故下的成功快切对电厂安全生产的意义,说明了在厂用电切换中尽快应用快切装置的必要性。 相似文献
87.
88.
89.
蒸汽是石油化工装置中最重要的物料。随着石油化工工业的迅猛发展 ,蒸汽在其中扮演着越来越重要的多重角色。因此 ,对蒸汽系统的平稳控制 ,对石油化工生产装置平稳、高效地运行是至关重要的。传统的蒸汽减压站自控系统基建投资大 ,紧急情况下靠人工手动操作稳定蒸汽压力系统 ,往往造成生产的波动或大面积的停车。针对传统蒸汽减压站自控系统的弱点 ,提出蒸汽减压站自控系统的优化设计方案 ,该方案得以在大型生产装置成功应用。新方案不但节省了大量的基建投资 ,而且取得了良好的生产效益 相似文献
90.