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991.
992.
Identification of drainage water allows assessing the effectiveness of water management. Passive capillary wick-type lysimeters
(PCAPs) were used to monitor water flux leached below the root zone under an irrigated cropping system. Wireless lysimeters
were developed for web-based real-time online monitoring of drainage water using a distributed wireless sensor network (WSN).
Twelve PCAP sensing stations were installed across the field at 90 cm below the soil surface, and each station measured the
amount of drainage water using two tipping buckets mounted in the lysimeter and continually monitored soil water contents
using two soil moisture sensors installed above the lysimeter. A weather station was included in the WSN to measure micrometeorological
field conditions. All in-field sensory data were periodically sampled and wirelessly transmitted to a base station that was
bridged to a web server for broadcasting the data on the internet. Communication signals from the in-field sensing stations
to the base station were successfully interfaced using low-cost Bluetooth wireless radio communication. Field experiments
resulted in high correlation between estimated and actual drainage with r
2 = 0.95 and confirmed a reliable wireless communication throughout the growing season. A web-linked WSN system provided convenient
remote online access to monitor drainage water flux and field conditions without the need for costly time-consuming supportive
operations. 相似文献
993.
Y. D. Kim J. Y. Min C. S. Karigar G. W. Cheong J. W. Kim M. S. Choi 《Plant Breeding》2007,126(6):634-637
A simple and rapid colorimetric method for the determination of caffeine has been developed. Tea tree lines from the Hadong region in South Korea differ widely in their caffeine contents and this colorimetric method facilitated an efficient screening strategy for the selection of low‐caffeine‐containing lines. A high correlation was observed between the values obtained with colorimetric and high‐performance liquid chromatographic analysis. Among the selected tree lines, the caffeine content for the lowest caffeine‐containing tea tree line (H‐19) was 178.35 μg/g dry weight basis, which was 61‐fold less productive than the highest caffeine‐producing tea tree line (H‐82). Caffeine contents of the selected tea tree lines remained similar during the corresponding collection periods. The colorimetric method is of great practical value in screening low‐caffeine‐containing tea trees. 相似文献
994.
Kwon Soo-Jeong Roy Swapan Kumar Yu Jang-Hwan Cho Seong-Woo Kim Hag-Hyun Boo Hee-Ock Woo Sun-Hee 《Journal of Crop Science and Biotechnology》2019,22(5):465-474
Journal of Crop Science and Biotechnology - The root of Platycodon grandiflorum is used as traditional oriental medicine in Asian countries since ancient times to treat bronchitis, tonsillitis,... 相似文献
995.
土地整理是增加耕地面积,提高土地质量,实现农村经济社会发展的重要举措;同时地面整理也是防止土壤侵蚀的重要措施之一。土地整理是一个需要多项技术支持的综合工程。与水田相比,耕地的地面形状比较复杂,因此地块设计的地形数据和设计方法也繁多。耕作田块是耕作的基本单元,田块设计包括田块的方向、形状、规模等因素,在设计当中要采取智能化、简单化、精确化的算法,以便适应多种多样的地形以及地质条件。该文在田块整理设计中利用一般n次曲面方程的求解算法提出了适应各种地形条件和整理对象要求的田块整理设计面确定方法。 相似文献
996.
Laland KN Sterelny K Odling-Smee J Hoppitt W Uller T 《Science (New York, N.Y.)》2011,334(6062):1512-1516
Fifty years ago, Ernst Mayr published a hugely influential paper on the nature of causation in biology, in which he distinguished between proximate and ultimate causes. Mayr equated proximate causation with immediate factors (for example, physiology) and ultimate causation with evolutionary explanations (for example, natural selection). He argued that proximate and ultimate causes addressed different questions and were not alternatives. Mayr's account of causation remains widely accepted today, with both positive and negative ramifications. Several current debates in biology (for example, over evolution and development, niche construction, cooperation, and the evolution of language) are linked by a common axis of acceptance/rejection of Mayr's model of causation. We argue that Mayr's formulation has acted to stabilize the dominant evolutionary paradigm against change but may now hamper progress in the biological sciences. 相似文献
997.
Solvated electrons in alkali metal-ammonia solutions have attracted attention as a prototype electronic conductor and chemical reducing agent for over a century. However, solvated electrons have not been realized in a high-temperature melt or glass of an oxide system to date. We demonstrated the formation of persistent solvated electrons in both a high-temperature melt and its glass by using the thermally stable electride [Ca(24)Al(28)O(64)](4+)·4e(-) (C12A7:e(-)) and controlling the partial pressure of oxygen. The electrical and structural properties of the resulting melt and glass differ from those of the conventional C12A7:O(2-) oxide, exhibiting metallic and hopping conduction, respectively, and a glass transition temperature that is ~160 kelvin lower than that of C12A7:O(2-) glass. Solvated electrons reside in cage structures in C12A7:e(-) and form a diamagnetic paired state. 相似文献
998.
Kim JS Lagrange T Reed BW Taheri ML Armstrong MR King WE Browning ND Campbell GH 《Science (New York, N.Y.)》2008,321(5895):1472-1475
The microstructure and properties of a material depend on dynamic processes such as defect motion, nucleation and growth, and phase transitions. Transmission electron microscopy (TEM) can spatially resolve these nanoscale phenomena but lacks the time resolution for direct observation. We used a photoemitted electron pulse to probe dynamic events with "snapshot" diffraction and imaging at 15-nanosecond resolution inside of a dynamic TEM. With the use of this capability, the moving reaction front of reactive nanolaminates is observed in situ. Time-resolved images and diffraction show a transient cellular morphology in a dynamically mixing, self-propagating reaction front, revealing brief phase separation during cooling, and thus provide insights into the mechanisms driving the self-propagating high-temperature synthesis. 相似文献
999.
Wentworth P McDunn JE Wentworth AD Takeuchi C Nieva J Jones T Bautista C Ruedi JM Gutierrez A Janda KD Babior BM Eschenmoser A Lerner RA 《Science (New York, N.Y.)》2002,298(5601):2195-2199
Recently, we showed that antibodies catalyze the generation of hydrogen peroxide (H2O2) from singlet molecular oxygen (1O2*) and water. Here, we show that this process can lead to efficient killing of bacteria, regardless of the antigen specificity of the antibody. H2O2 production by antibodies alone was found to be not sufficient for bacterial killing. Our studies suggested that the antibody-catalyzed water-oxidation pathway produced an additional molecular species with a chemical signature similar to that of ozone. This species is also generated during the oxidative burst of activated human neutrophils and during inflammation. These observations suggest that alternative pathways may exist for biological killing of bacteria that are mediated by potent oxidants previously unknown to biology. 相似文献
1000.
As universities have become more integrated into their communities and regions, their host cities have become locations of choice for the highly educated facilitating increased innovation and productivity rates in several locales. Recent transitions toward knowledge-driven economies have also intensified growing geographic divides along the lines of education and raised concerns about the possibility of brain drain in a growing number of cities/regions. This study examines the changing geography of highly educated individuals (2000–2017) with a focus on small and medium-sized U.S. metropolitan areas with and without research universities. Results indicate the continuing trend of divergence among regions, but research universities are found to complement (the lack of) talent agglomeration and generate spatial spillovers beyond the county boundaries. 相似文献