全文获取类型
收费全文 | 93777篇 |
免费 | 5148篇 |
国内免费 | 7184篇 |
专业分类
林业 | 10221篇 |
农学 | 7160篇 |
基础科学 | 4982篇 |
14057篇 | |
综合类 | 45269篇 |
农作物 | 4267篇 |
水产渔业 | 3071篇 |
畜牧兽医 | 9600篇 |
园艺 | 2892篇 |
植物保护 | 4590篇 |
出版年
2024年 | 366篇 |
2023年 | 1275篇 |
2022年 | 2024篇 |
2021年 | 2324篇 |
2020年 | 2370篇 |
2019年 | 3116篇 |
2018年 | 1896篇 |
2017年 | 3121篇 |
2016年 | 3871篇 |
2015年 | 3338篇 |
2014年 | 4419篇 |
2013年 | 4797篇 |
2012年 | 6813篇 |
2011年 | 6924篇 |
2010年 | 5731篇 |
2009年 | 5661篇 |
2008年 | 5262篇 |
2007年 | 6226篇 |
2006年 | 5456篇 |
2005年 | 4578篇 |
2004年 | 3504篇 |
2003年 | 3035篇 |
2002年 | 2370篇 |
2001年 | 2069篇 |
2000年 | 1927篇 |
1999年 | 1567篇 |
1998年 | 1353篇 |
1997年 | 1315篇 |
1996年 | 1264篇 |
1995年 | 1257篇 |
1994年 | 1202篇 |
1993年 | 1075篇 |
1992年 | 1053篇 |
1991年 | 916篇 |
1990年 | 796篇 |
1989年 | 631篇 |
1988年 | 457篇 |
1987年 | 316篇 |
1986年 | 152篇 |
1985年 | 56篇 |
1984年 | 31篇 |
1983年 | 25篇 |
1982年 | 24篇 |
1981年 | 25篇 |
1980年 | 25篇 |
1979年 | 20篇 |
1978年 | 19篇 |
1976年 | 12篇 |
1956年 | 12篇 |
1955年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
952.
953.
Discussion of the Application and Foreground of Falling Water Aeration with the Process of Sewage Treatment
下载免费PDF全文
![点击此处可从《保鲜与加工》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The engineering design of sewage treatment plant for the Chongqing city, P. R. China is analyzed in this paper. Considering the situation of China and other projects, the characteristics of falling water reactor for the environment protection project and economy of investment is introduced ; the application and foreground of falling water aeration in the process of sewage treatment is discussed, such as Oxidation - ditch, SBR, and so on. The conclusion indicated that the falling water aeration can be designed and used as an independent aeration, and, it is an upgraded technology of sewage treatment which is adaptive for city water environment control in middle and small towns in China. The falling water aeration may reduce running cost of the sewage treatment plant, is adaptive for foothill and the mountainous areas, and reduces project investment and environments damage. 相似文献
954.
不同花生品种侧枝发育动态与产量性状研究 总被引:1,自引:0,他引:1
花生一级侧枝发育具有不均衡性。第一、二对侧枝出现早,伸长快,其他一级侧枝出现晚,伸长慢。86036-26-1第一、二对侧枝发育相对较早,而其他一级侧枝发育较晚;海花1号和豫花1号第一、二对发育相对较晚,而其他一级发育较快;豫花7号和鲁花9号居中。海花1号一级侧枝及第一对侧枝的二级侧枝数最多,86036-26-1的一级侧枝数及第一对侧枝的二级侧枝数量少。在花针期之前第一对侧枝的伸长与主茎基本同步;花针期之后,第一对侧枝伸长速度超过主茎。86036-26-1的一级侧枝长及株高居首位。86036-26-1第一、二对侧枝饱果率,产量居第一,豫花7号居第二。海花1号虽然荚果数较多,但第一、二对侧枝孢果率较低,产量也较低;鲁花9号居中。 相似文献
955.
956.
957.
Xie Ming Guo Xiaoyu Wang Yanchun 《保鲜与加工》1993,(6):134-137
A minimum ring-band mathematical definition :In the done ring-band, there are at least two inner points and two outer points which scatter staggeringly on the circumference. With this definition as the rule of searching calculation' s ending,a fast numerical algorithm of gaining the minimum ring-band of a closed curve was suggested:Make a ring-band with the four points scattered staggeringly,then replace the old points with new ones continuously until all the points are located within the ring-band. The method was used in an application example to measure the spindle rotating precision of machine tools. 相似文献
958.
《Journal of Cereal Science》2014,59(3):451-456
Brans of 23 traditional and 12 improved (both red and white) rice varieties in Sri Lanka were screened for anti-amylase and anti-glycation activities in vitro. Varieties which showed the highest inhibitory activities at screening were further investigated for anti-glucosidase and glycation reversing as anti-diabetic properties. The same varieties were studied for selected antioxidant properties. Significantly high anti-amylase and anti-glycation activities were observed for bran extracts of red varieties compared to white varieties at screening. Traditional red rice varieties, Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti, exhibited significant and dose dependent anti-amylase, anti-glycation and glycation reversing activities. These varieties also showed marked antioxidant properties. It is concluded that brans of Sri Lankan traditional red rice varieties Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti may be potential food supplements for diabetes. 相似文献
959.
Research on Relationship between the Level of Urbanization and the Growth of Real Estate Investment
下载免费PDF全文
![点击此处可从《保鲜与加工》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The population proportion index is usually introduced to measure the level of urbanization, which is an important index to the national economy. The fast development of urbanization would inevitably cause the increase of the investment in real estate industry. Introducing the Granger Test of Causality analytical method, in this paper the relationship between the level of urbanization and the investment in real estate industry from 1986 to 2003 in China is analyzed. It reveals that both of them are on the stage of constant up - rising, and the correlation index of 0. 205 shows that the relationship between them is a mutual promoting causality. 相似文献
960.
Wang Jianping Mi Linshu Chen Gang 《保鲜与加工》1993,(6):32-37
The angular frequency and decaying constant of each copmonect for the
transient waveform in power systems were obtained by using the discrete Fourier transform; the amplitude and phase angle were calculated in the linear curve fitting method. And all of the parameters obtained above were treated in an unified optimization by using the curve fitting optimization of the least square method of general nonlinear funcrion so as to get the results of waveform analysis. Two examples are included. 相似文献