全文获取类型
收费全文 | 50135篇 |
免费 | 4336篇 |
国内免费 | 2502篇 |
专业分类
电工技术 | 2351篇 |
技术理论 | 5篇 |
综合类 | 5853篇 |
化学工业 | 6452篇 |
金属工艺 | 2394篇 |
机械仪表 | 1610篇 |
建筑科学 | 7003篇 |
矿业工程 | 2537篇 |
能源动力 | 1745篇 |
轻工业 | 3689篇 |
水利工程 | 6505篇 |
石油天然气 | 2438篇 |
武器工业 | 201篇 |
无线电 | 2317篇 |
一般工业技术 | 4036篇 |
冶金工业 | 3563篇 |
原子能技术 | 436篇 |
自动化技术 | 3838篇 |
出版年
2024年 | 225篇 |
2023年 | 709篇 |
2022年 | 1242篇 |
2021年 | 1452篇 |
2020年 | 1372篇 |
2019年 | 1300篇 |
2018年 | 1197篇 |
2017年 | 1401篇 |
2016年 | 1550篇 |
2015年 | 1585篇 |
2014年 | 2714篇 |
2013年 | 2607篇 |
2012年 | 3284篇 |
2011年 | 3480篇 |
2010年 | 2658篇 |
2009年 | 2863篇 |
2008年 | 2580篇 |
2007年 | 3383篇 |
2006年 | 3119篇 |
2005年 | 2818篇 |
2004年 | 2418篇 |
2003年 | 2163篇 |
2002年 | 1893篇 |
2001年 | 1593篇 |
2000年 | 1344篇 |
1999年 | 1094篇 |
1998年 | 775篇 |
1997年 | 677篇 |
1996年 | 573篇 |
1995年 | 528篇 |
1994年 | 408篇 |
1993年 | 368篇 |
1992年 | 275篇 |
1991年 | 183篇 |
1990年 | 197篇 |
1989年 | 171篇 |
1988年 | 143篇 |
1987年 | 111篇 |
1986年 | 78篇 |
1985年 | 61篇 |
1984年 | 60篇 |
1983年 | 26篇 |
1982年 | 27篇 |
1981年 | 38篇 |
1980年 | 31篇 |
1979年 | 34篇 |
1977年 | 18篇 |
1976年 | 18篇 |
1975年 | 20篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
I. S. W. B. Prasetya 《Formal Aspects of Computing》1994,6(4):466-470
UNITY, introduced by Chandy and Misra [ChM88], is a programming logic intended to reason about temporal properties of distributed programs. Despite the fact that UNITY does not have the full power of, for example, linear temporal logic, it enjoys popularity due to its simplicity.There was however a serious problem with the Substitution Rule. The logic is incomplete without the rule, and with the rule it is inconsistent. 相似文献
53.
三峡水库减淤增容调度方式研究——多汛限水位调度方案 总被引:8,自引:0,他引:8
本文建议在汛期中小流量时(Q<35000m3/s),将坝前水位维持在148~151m;出现汛情且流量更较大后,将坝前水位降低到143m;入库流量大于35000m3/s且短期预报将出现大于十年一遇洪水时,预泄洪水到135m.按这一调度,汛期约80%时间可以维持在较高水位,一般洪水期。汛限水位143m不影响坝区通航,135m水位迎洪可大量增加防洪库客。到100年后可减淤30亿m3,增加防洪库容约40亿m3.变动回水区减淤40%,优化了坝区水沙搭配,可改善通航条件。降低库区洪水位,缓解防洪与移民的矛盾。可对发电带来较大好处:提高发电效益,减少粗沙过机。初期水库排沙比大于原方案,可减轻下游冲刷。同时,可减小三峡汛初泄水与鄱阳湖防洪的矛盾。 相似文献
54.
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
55.
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
56.
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
57.
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
58.
59.
长江螺山站高水位流量关系和城陵矶(莲花塘)控制水位的研究 总被引:4,自引:0,他引:4
螺山站高水位流量关系是确定长江城陵矶(莲花糖)控制水位的基本依据,从基本的河道水力学规律出发,考虑涨落率修正、瞬时比降修正,计算各时段点的代表性比降,和相应糙率,求出均值,根据断面资料,得出高水位的稳定流曲线,并以各日流量转化的稳定流点,进行验证,精度很好,分析了河段区间流量对螺山站稳定流量的影响。阐明了螺山站稳定流量的变化情况和趋势,推求了各次大洪水的超额洪量,计算出莲花糖以上的总入流,根据现今的湖区及槽蓄容积进行洪水演进,计算1954年特大洪水的超额洪量,并分析节三峡水库拦洪后对长江中下游超额水量的影响;对莲花塘不同防洪控制水位进行了技术经济分析和评价,提出了抬高控制水位的具体建议。 相似文献
60.