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991.
在日前结束的全国首届《中国学术期刊 《沈阳师范大学学报(自然科学版)》2001,19(1)
本刊荣获首届《CAJ-CD规范》执行优秀奖
在日前结束的全国首届《中国学术期刊(光盘版)检索与评价数据规范》执行评优活动中,《沈阳师范学院学报(自然科学版)》主要数据规范达到标准要求,荣获执行优秀奖。
此次评优不设奖级,全国5100余种入编期刊中近2000种期刊参评。本刊自1999年第1期入编《中国学术期刊(光盘版)》和“中国期刊网(Chinajournal.net)”,1999年第3期起,在执行有关国家标准和《中国高等学校自然科学学报编排规范》的基础上,全面执行《中国学术期刊(光盘版)检索与评价数据规范》,编辑出版质量稳步提高。本刊获此殊荣,也得益于广大作者和读者的大力支持和配合,在此谨致谢意。
本刊加入万方数据资源系统(ChinaInfo)数字化期刊群的声明
为实现科技期刊编辑、出版发行工作的电子化,推进科技信息交流的网络化进程,《沈阳师范学院学报(自然科学版)》已入网“万方数据资源系统(ChinaInfo)数字化期刊群”。向本刊投稿并刊发的稿件文章,将一律由编辑部统一纳入万方数据资源系统(ChinaInfo),进入因特网提供信息服务。凡有不同意者,请另投它刊。本刊所付稿酬包括刊物内容上网服务报酬,不再另付。欢迎广大作者和读者通过因特网进入万方数据资源系统(ChinaInfo)查询浏览本刊内容,投稿并提出宝贵意见和建议,或征订本刊。
沈阳师范学院学报编辑部
本刊迁址启事
本刊已随校迁入新址:沈阳市皇姑区黄河北大街253号。邮政编码:110034,编辑部电话:024-86574467。
沈阳师范学院学报编辑部 相似文献
992.
IP多播在数字视频监控系统中的实现 总被引:2,自引:0,他引:2
张小 《上海大学学报(自然科学版)》2000,6(6):533-537
围绕IP多播在数字视频监控系统中的实现,深入讨论了系统引入IP多播技术所涉及的一系列关键技术及其相关的实现方法,IP多播流程的建立、基于Winsock的IP多播技术的实现步骤、舆层协议的选择、网络流量控制策略以及用户权限控制的实现等技术在文中都提供了其具体的解决办法,该系统采用Digital 21230芯片硬件实现音视频MPGE-1标准的实时压缩,应用软件实时解压缩以及系统多功能操作等,软件基于W 相似文献
993.
探讨了在VB中调用DLL以实现数据采集,介绍了在VC^++中建立DLL以及在VB中调用DLL的方法,解决了高频信号的采样问题。 相似文献
994.
中文网页自动分类新算法 总被引:8,自引:0,他引:8
为了有效地组织因特网上极其丰富的信息资源 ,通过分析中文和中文网页的特点 ,提出了一种新的中文网页的自动分类算法。这种算法主要利用字间的相关信息、词频以及页面的标记信息等 ,提取网页特征 ,并计算可调的词频加权参数 ,然后通过本类和非本类训练 ,建立专家数据库。实验表明 ,该算法可以获得 80 %以上的网页分类准确率 相似文献
995.
996.
997.
ZHU Shixing SUN Shufen HUANG Xueguang HEYuzhen(Tianjin Institute of Geology Mineral Resources Chinese Academy of GeologicalSciences Tianjin China)ZHU Gengxin SUN Lixin & ZHANG Kuan(Regional Geological Survey Institute Hebei Bureau of Geology Exploration Langfang China)Correspondence should be addressed to Zhu Shixing 《科学通报(英文版)》2000,45(9):841-847
In 1997 and 1998, hundreds of specimens of megascopic carbonaceous compressions or algal fossils were found from ∼ 1800-million-year
old Changzhougou Formation, which is the lowermost unit of the latest Palaeoproterozoic Changcheng Group (∼1 600–1 800 Ma)
in the Xinglong-Kuancheng areas at the middle Yanshan Range, North China. They are discoid, ellipsoid and sausage-like, namely
shaped likeChuaria Shouhsiennia (Ellipsophyta) andTawuia. By adopting HF acid-resistant maceration coupled with scanning electron microscope and petrologic section, the authors made
a preliminary research on the histology for some circular and ellipsoid carbonaceous compressions, namelyChuaria- andShouhsienia-like forms, in addition to their morphology. The following three types of multicellular tissues have been found in the fragments
of them: colony-like, pseudoparenchyma-like and parenchyma-like. All of the new data about multicelluar tissues not only supply
a very important basis in histology to determine the biological affinity of multicellular algal remains for the Changzhougou
carbonaceous compressions newly found, but also provide reliable fossil evidence to prove that metaphytes originated at least
1 800 million years ago. 相似文献
998.
Global pollution shown by lead and cadmium contents in precipitation of polar regions and Qinghai-Tibetan Plateau 总被引:1,自引:1,他引:0
XIAO Cunde QIN Dahe YAO Tandong RENJiawen & LI Yuefang(Laboratory of Ice Core Cold Region Environment Lanzhou Institute of Glaciology andGeocryology Chinese Academy of Sciences Lanzhou China)Correspondence should be addressed to Ren Jiawen 《科学通报(英文版)》2000,45(9):847-853
The analysis of the major ions, lead and cadmium has been performed for snow-pit samples collected from the Arctic, the Qinghai-Tibetan
Plateau and the Antarctic Ice Sheet. These snow pits were excavated respectively from the snowpack in Canadian Northwest Territory
(NWT) and the central Arctic, three glaciers on the Qinghai-Tibetan Plateau and surface snow along the route of the International
Trans-Antarctic Expedition (ITAE). The source regions for the lead pollution of central Arctic have been identified by analyzing
of stable lead isotopic ratios, meteorological and atmospheric chemistry studies. It shows that the central Arctic is still
under intensive lead input, despite the fact that lead content in Greenland Ice Sheet displays a rapid decreasing since the
1970s due to US and some European countries’ campaigns to reduce lead-containing gasoline-additives. This is because there
are multiple lead sources for the central Arctic, including the countries that have not performed gasoline-additives reducing.
The backgrounds of atmospheric aerosol compositions, as well as the concentrations of lead and cadmium in precipitation of
the early 1990s, are contrasted among the Arctic, Antarctica and Qinghai-Tibetan Plateau. The measured lead content in the
snowfall at the typical sites of the three regions is divided into natural (background) and anthropogenic components. It is
found that natural lead concentration (mainly crustal and/or sea-salt lead) is roughly equal among the three regions (< 3×1012g · g1). However, the percentage of the natural lead to the measured lead is negligible in precipitation in the central Arctic and
the Qinghai-Tibetan Plateau, while it is considerable in Antarctic precipitation. The anthropogenic component of lead (>50%
in Antarctic precipitation, >97% in the Arctic and the Qinghai-Tibetan Plateau ) is mainly responsible for the lead input
to both polar regions and to the Qinghai-Tibetan Plateau. Lead pollution may have spread into the whole troposphere and the
most remote regions on earth. 相似文献
999.
Fig. The absorption 《科学通报(英文版)》2000,45(10):914-920
Histidine coordinated to Chi a is a distinct characteristic of Chl ain vivo. By using histidine analogue of 1-methylimidazole (C4H6N22) and measuring the UV/vis absorption, CD and MCD spectra of the interaction between C4H6N2 and Chl a in CCI4, we have obtained that: (i) In pure CCl4 solvent, Chl a molecule is in five-coordinate state, and two Chl a molecules form an asymmetric compact-dimer with strong
coupling interaction. We propose that the two Chl a molecules are connected by two unequally coordinated Mg-O bonds (the two
oxygen atoms come from the C=O of C131 keto and C17 ester, respectively); (ii) when the molar ratio of C4H6N2/Chl a is 0.5 or 1 (corresponding to 2Chl a · 1C4H6N2 and 2Chl a · 2C4H6N2, respectively), significant changes have been observed in the absorption, CD and MCD spectra, which indicate that the Chl
a remains in dimer form, but the coupling interaction between them reduces greatly. We postulate that C4H6N2 replaces the ligation of C=O of C17 ester and C131 keto to Mg atoms sequentially. The two Chl a molecules linked by two weakly interacted Mg…O bonds form a relaxed-dimer. The
structure of the model is essentially similar to that of the primary electronic donor, P680, of photosystem II in high plants and algae. 相似文献
1000.
为了研究“压胀松动”增产技术的增产效果和施工工艺,在延长石油管理局子长油矿对4207裸眼井进行了现场试验.介绍了裸眼井“压胀松动”增产技术的基本原理、该井现场试验所需岩石力学参数的测定、药量的计算及装药设计.并对施工工艺和实验结果进行了分析和研究,说明“压胀松动”增产技术对此井是有效的. 相似文献