全文获取类型
收费全文 | 1802篇 |
免费 | 156篇 |
国内免费 | 71篇 |
专业分类
林业 | 145篇 |
农学 | 100篇 |
基础科学 | 69篇 |
258篇 | |
综合类 | 762篇 |
农作物 | 67篇 |
水产渔业 | 82篇 |
畜牧兽医 | 371篇 |
园艺 | 43篇 |
植物保护 | 132篇 |
出版年
2024年 | 6篇 |
2023年 | 52篇 |
2022年 | 68篇 |
2021年 | 75篇 |
2020年 | 55篇 |
2019年 | 67篇 |
2018年 | 46篇 |
2017年 | 64篇 |
2016年 | 85篇 |
2015年 | 64篇 |
2014年 | 96篇 |
2013年 | 110篇 |
2012年 | 137篇 |
2011年 | 129篇 |
2010年 | 105篇 |
2009年 | 117篇 |
2008年 | 99篇 |
2007年 | 136篇 |
2006年 | 110篇 |
2005年 | 80篇 |
2004年 | 72篇 |
2003年 | 54篇 |
2002年 | 35篇 |
2001年 | 43篇 |
2000年 | 20篇 |
1999年 | 15篇 |
1998年 | 20篇 |
1997年 | 15篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 1篇 |
1991年 | 8篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有2029条查询结果,搜索用时 15 毫秒
41.
The biological effects of ELFMES including proliferation and apoptosis of cells as well as the damage of DNA are initially evaluated with the treatment of plant cells and human pulmonary fibroblasts in low frequency magnetic fields with certain intensity and different time intervals in vitro. Cell culture, counting in vitro, fluorescent dyeing analysis and single cell gel electrophoresis are adopted. The results demonstrate that the electromagnetic field with the intensity of 3mT can affect the proliferation and apoptosis of cells significantly. 相似文献
42.
In accordance with the special characteristics of state medium-sized construction enterprises and their reform objects of "having a free hand and enlivening", the suitable objective model, the stock cooperative system for state medium-sized construction enterprises has been put forward in this paper by analyzing the system mechanism of stock cooperative system enterprises. Then the causes for it were expounded. 相似文献
43.
Under the background of the new rural construction in China, it is an important scientific question and an urgent social task to construct the harmonious society and to achieve the sustainable regional development on how to construct concentrative residence and manage the human habitat environment in the fast industrializing and typically urbanizing area. This paper analyzed the problems in the construction of the human habitat envi- ronment in the rural area of southern Jiangsu, discussed the methodologies of planning and design for rural con- centrative residence, researched the human habitat environment improvement technologies, and put forward the resolution of the recycling community for the rural inhabitation, which aimed at demonstrating the practicing in rapidly urbanizing regions. 相似文献
44.
Tu Yaqing Huang Shanglian Li Zushu 《保鲜与加工》1993,(6):8-15
Based on the model of Human Simulation Intelligent Controller (HSIC)
presented briefly, a detailed algorithm was described for the servo system control by using the method of HSIC. Simulation results obtained proves the good performance of the control algorithm. 相似文献
45.
Analyses the thermal environment parameters from physiological aspect and from psychological aspect respectively. Introduces the conception of thermal comfort of human body from heat balance aspect. Presents some measures to improve indoor thermal environment and advance thermal comfort of human body. Analyses the influence of indoor thermal environment on thermal comfort of human body and some questions on the aspect of this research, also puts forward some advices. 相似文献
46.
The design of multi-controller and multi-mode control law is presented for the three-link Acrobot on horizontal bar by employing Human simulated intelligent control method based on sensory-motor Schema.Imitated the characteristics of gymnast's swing-up and handstand movement,the control process of robot is divided by six sequence phase.Then the sensory cell and motor cell and the group of sensory-motor schema is designed based on the analysis of quality-quantity combination.The simulation results show that the controller ensures the gesture and the energy to the desired goal,farther more the motion control of giant swing backword is realized in the simulation. 相似文献
47.
The externality of surrounding is introduced into the 2-capital of economical increasing models, which includes human factors, to explore the influences of circumstances contradiction on the human capital formation. The normal and special nash equilibrium of environmental and human capital is presented through a limited boundary model of overlapping generations. The character of equilibrium trail and its economical meaning are examined. The study on the model shows that laissez faire economy will be either stagnant,growing,or collapsing in the long-run,depending on the returns of the learning technology with respect to the two kinds of capital,the initial state of economy,and the relative price of the environmental and consumption goods. 相似文献
48.
The maintenance and gain of enterprise value have something to do with human capital. Human capital impels the realization of enterprise value through their inter-relationship, depending on given organization environment. This article systemically analyses tier value chain, paratactic value chain and network value chain, which are formed in the course of the creating value by human capital, then educes the adjustors of the management and forms according to the environment. 相似文献
49.
Jeffrey A. McNeely 《Euphytica》2006,148(1-2):5-15
Summary While the issue of invasive alien species has important biological components, economic factors such as global trade deserve
much greater attention for several reasons. First, virtually all of our planet’s ecosystems have a strong and increasing anthropogenic
component that is being fed by increasing globalisation of the economy. Second, people are designing the kinds of ecosystems
they find productive or congenial, incorporating species from all parts of the world through quicker and more efficient means
of transportation. And third, growing travel and trade, coupled with weakening customs and quarantine controls, mean that
people are both intentionally and inadvertently introducing alien species that may become invasive. The great increase in
the introduction of alien species that people are importing for economic, aesthetic, accidental, or even psychological reasons
is leading to more species invading native ecosystems, with disastrous results: they become invasive alien species (IAS) that
have significant deleterious effects on both ecosystems and economies. This paper examines some of the important non-biological
dimensions of the IAS problem, including historical, economic, cultural, linguistic, health, sociological, management, legal,
military, ethical, and political dimensions. These are addressed in terms of the causes, consequences, and responses to the
problem of IAS. These dimensions of IAS are fundamental, and successfully addressing the problem will call for greater collaboration
between different economic sectors and among a wide range of disciplines. The Convention on Biological Diversity, the negotiations
of the World Trade Organisation, and many other international agreements offer important opportunities for addressing the
complex global problems of IAS through improved international cooperation. 相似文献
50.
As the development of knowledge economic , human resource has been the core of the world economic .So searching the reasonable evaluating and managing methods becomes one of the hot issues which have been concerned by people . Traditional evaluating methods of human resource are simple and direct , but they greatly depend on people's subjective judgement and experience . In order to overcome the default , this paper puts forward the method of synthetically evaluation on rough sets, which takes advantage of the rough sets theory, the concept of information entropy and relative analysis to filter the original indexes, then to standardize the importance degree of every index and get the weight of every index. Synthetically valuation model and corresponding arithmetic are summed up. Finally the sample illuminates the validity and feasibility of this method. 相似文献