全文获取类型
收费全文 | 508篇 |
免费 | 0篇 |
专业分类
化学工业 | 5篇 |
轻工业 | 2篇 |
冶金工业 | 496篇 |
自动化技术 | 5篇 |
出版年
2014年 | 1篇 |
2010年 | 1篇 |
2005年 | 1篇 |
2003年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 18篇 |
1998年 | 142篇 |
1997年 | 82篇 |
1996年 | 63篇 |
1995年 | 29篇 |
1994年 | 21篇 |
1993年 | 37篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 10篇 |
1977年 | 17篇 |
1976年 | 33篇 |
1975年 | 1篇 |
排序方式: 共有508条查询结果,搜索用时 984 毫秒
501.
502.
A construct of IL-2 and pseudomonas exotoxin (PE40) has been genetically engineered. An aliquot of 100 microliter of the chimeric protein, radiolabelled with I125, was administered to healthy rats by various routes. At different intervals, ocular and non ocular tissues were removed and the levels of the radiolabelled chimeric protein IL-2-PE40 measured. Systemic administration of IL2-PE40 either intravenously (IV) or intraperitoneally (IP) leads to high levels of the drug in the blood, liver and spleen. Little or no radioactivity is observed within the ocular tissues using this route. On the other hand, local administration of the drug either as subtenon injection or as eye drops resulted in a very high concentration of the drug within the conjunctiva, cornea and sclera, with little radioactivity detected systemically. Subtenon injection induced a significant drug level within the optic nerve. With the drops, the chimeric protein was also detected, in low levels, intraocularly. 相似文献
503.
In 184 rabbits experiments it was demonstrated that debridement with suction of the damaged portion of the brain within the macroscopically intact brain tissue and a leak-proof suture undertaken on the 1st and 3rd day following a penetrating skull-brain trauma in irradiated with 400 r and non-irradiated animals prevents heamorrhagic and purulent complications, permits primary healing of the wound, and a nearly 100% survival of the animals. The irradiated animals without debridement died in 67% of cases, non-irradiated--in 43%. Debridement limited to wound debris washing-out failed to free the irradiated animals from purulent complications, but prevented the development of cerebral haematomas, the mortality being reduced to 40%. In the non-irradiated animals such debridement did not alter the mortality figures. 相似文献
504.
505.
506.
507.
A real-time, microprocessor-based simulator was designed to study the packet transmission of voice on a broadcast type local area network, based on the CSMA/CD and Hymap multiple-access protocols. The speech quality is evaluated subjectively. A packetization-frozen protocol is used to eliminate the successive collisions due to possible synchronization of packet generation among stations. The variance of the network delay is bounded by discarding packets which have not been transmitted within a certain amount of time. Smooth speech output can be obtained by introducing additional buffer delay at the receiver. 相似文献
508.
In this paper we estimate the size of several categories of "Israeli" immigrants in the United States. According to the 1990 U.S. census, there were about 95,000 Israeli-born immigrants in the United States in that year. Using the language and ancestry information available in the Public Use Microdata Sample (PUMS) of the 1990 census, we estimate that of this total, about 80,000 are Jews and 15,000 are Palestinian Arabs born in Israel. In addition to the Israeli-born, we present a range for the number of Jewish immigrants from Israel who are not Israeli-born (about 30,000-56,000). Thus our estimate for the total number of Jewish immigrants from Israel in the United States in 1990 is between 110,000 and 135,000. Fertility information available in the PUMS, also enable us to provide estimates for the number of second-generation Israelis in the United States in the 1990 (about 42,000). Finally, using both the 1980 and 1990 PUMS, we provide estimates for the rate of return migration among Israeli-born Jewish immigrants in the United States. 相似文献