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151.
《Arabian Journal of Chemistry》2022,15(11):104302
Traditional Chinese medicine (TCM) is the key to unlock treasures of Chinese civilization. TCM and its compound play a beneficial role in medical activities to cure diseases, especially in major public health events such as novel coronavirus epidemics across the globe. The chemical composition in Chinese medicine formula is complex and diverse, but their effective substances resemble “mystery boxes”. Revealing their active ingredients and their mechanisms of action has become focal point and difficulty of research for herbalists. Although the existing research methods are numerous and constantly updated iteratively, there is remain a lack of prospective reviews. Hence, this paper provides a comprehensive account of existing new approaches and technologies based on previous studies with an in vitro to in vivo perspective. In addition, the bottlenecks of studies on Chinese medicine formula effective substances are also revealed. Especially, we look ahead to new perspectives, technologies and applications for its future development. This work reviews based on new perspectives to open horizons for the future research. Consequently, herbal compounding pharmaceutical substances study should carry on the essence of TCM while pursuing innovations in the field. 相似文献
152.
The problem of minimizing a nondifferential functionx f(x) (subject, possibly, to nondifferential constraints) is considered. Conventional algorithms are employed for minimizing a differential approximationf
off (subject to differentiable approximations ofg). The parameter is adaptively reduced in such a way as to ensure convergence to points satisfying necessary conditions of optimality for the original problem.This research was supported by the UK Science and Engineering Research Council, the National Science Foundation under Grant No. ECS-8121149, and the Joint Services Electronics Program, Contract No. F49620-79-C-0178. 相似文献
153.
Lumbierres M Palomo JM Kragol G Roehrs S Müller O Waldmann H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(24):7405-7415
A new flexible and efficient methodology for the solid-phase synthesis of lipidated peptides has been developed. The approach is based on the use of previously synthesized building blocks and overcomes the limitations of previously reported methods, since long doubly lipidated peptides can be synthesized by using this route. Furthermore, it was thus possible to prepare a large number of N- and H-Ras peptides bearing a wide range of reporter and/or linking groups--efficient tools for the investigation of biological processes. In terms of efficiency and flexibility this solid-phase method is superior to the solution-phase synthesis. It gives pure peptides in multimilligram amounts within a much shorter time and with superior overall yield. 相似文献
154.
Time shift correction in second-order liquid chromatographic data with iterative target transformation factor analysis 总被引:4,自引:0,他引:4
Enric Comas R. Ana Gimeno Joan Ferr Rosa M. Marc Francesc Borrull F. Xavier Rius 《Analytica chimica acta》2002,470(2):607-173
When the generalized rank annihilation method (GRAM) is applied to liquid chromatographic data with diode-array detection, an important problem is the time shift of the peak of the analyte in the test sample. This problem leads to erroneous predictions. This time shift can be corrected if a time window is selected so that the chromatographic profile of the analyte in the test sample is trilinear with the peak of the analyte in the calibration sample. In this paper we present a new method to determine when this condition is met. This method is based on the curve resolution with iterative target transformation factor analysis (ITTFA). The calibration and test matrices are independently decomposed into profiles and spectra, and aligned before GRAM is applied. Here we study two situations: first, when the calibration matrix has one analyte and second, when it has two analytes. When the calibration matrix has two analytes, we selectively determine the time window for the analyte to be quantified. There were considerably fewer prediction errors after correction. 相似文献
155.
Yan-Tao He 《Tetrahedron letters》2005,46(32):5393-5397
Longimicin C, a naturally occurring annonaceous acetogenin possessing a C2-symmetrical bis-THF moiety and a short hydrocarbon chain between its THF-containing region and a terminal γ-lactone, was synthesized for the first time. The total synthesis was successfully achieved by an iterative acetylene-epoxide coupling strategy. d-Mannitol was used to establish the bis-THF-containing segment, in which the additional stereochemistries were introduced by Sharpless dihydroxylations and intramolecular Williamson etherifications. Regioselective epoxide-openings by the appropriate terminal acetylenes allowed coupling and elaboration of all four fragments including the introduction of three essential hydroxyls into the proper sites of the target skeleton. 相似文献
156.
Massey University is a world-leading university in remote-instruction, online and mixed teaching based on the Stream teaching platform. This paper analyzed the advantages of the Stream teaching platform, resource utilization, course format, teaching team cooperation and course evaluation in Massey University. The paper also analyzed the enlightenment of teaching experience of Massey University to undergraduate teaching. During the outbreak of COVID-19 epidemic, drawing on Massey's experience, combined with the rapid development of information technology in China, the teaching team of organic chemistry adopted the multi-teaching strategy of "teacher-centered and student-centered", and the teaching mode of "teacher-led and self-taught by students". The online teaching practice of organic chemistry was carried out in agriculture university. It has been demonstrated that this model can effectively improve teaching effects. 相似文献
157.
158.
In this paper we articulate our philosophy and approach to the design and control of high speed data networks. The object is to put into perspective and to explain the coordination of various isolated pieces of detailed technical analyses that have been reported in several recent papers. In the process we summarize what we have learnt in our recent work and, also, we give indications of the direction of our future work. Our scheme integrates feedback and open loop control. The feedback control is exercised by sliding windows; access controllers regulate bursty sources. All our design proposals are rooted in asymptotic analyses; the justification for asymptotics comes from the largeness of the parameters, such as propagation delay, speed, window size, buffer size, and the number of virtual circuits. This analysis makes a strong case for operating in a specific moderate usage regime, and adaptive dynamic windowing algorithms are given that make this happen; moreover, when in this regime, buffers may be sized aggressively small without jeopardizing performance and the simplicity of the retransmission protocol. The topics in the paper are: model of communication, results on the steady-state behavior of the basic model, access control, small buffers and retransmission protocols, dynamic adaptive windows, bursty sources, and contrast with previous work.I. Mitrani's work was done while AT&T Bell Laboratories. 相似文献
159.
L. Malherbe 《Accreditation and quality assurance》2002,7(5):189-194
Human health risk assessment is a site-based approach used to identify the potential health hazards which are induced by an
old site contamination. For a proper evaluation of the daily doses of contaminants to which people will be exposed given the
future occupation of the site, both a characterization and a quantification of soil pollution are needed. Such information
can be provided by soil sampling. Thus the choice of the location, the number, depth and type of soil samples is very important
and ought to follow a well-defined strategy. A review of contaminated site sampling practices in Europe and North America
could not identify any completely formalized sampling strategy for human health risk assessment. On the contrary there are
several approaches which can be roughly classified into two categories: a systematic sampling scheme over the whole site,
on the one hand, and a sampling design driven by an initial knowledge of the contamination sources and fitted to the suspected
pollution pattern, on the other. The first approach provides a complete coverage of the site but it may be rather expensive
and entail useless sampling. The performance of the second depends on the quality of prior information. Actually both methods
can be combined as explained hereafter. In view of the specificity of each site, the requirements of health risk assessment
and the time and cost constraints, it seems difficult to work out a typical soil sampling strategy suitable for all sites.
However, some recommendations can be made according to the site dimensions, the nature, degree and heterogeneity of contamination,
and the (future) use of the site. The scientist should thus rely on a thorough examination of all available information (site
history, geology and hydrogeology, soil properties, contaminants behaviour , etc.) to delimit contaminated areas as homogeneous
as possible and then distribute the sampling points (e.g.using a sampling grid). They should also take the potential exposure
paths into account in order to define the areas and soil strata to be sampled as a priority. Statistical and geostatistical
tools can be helpful for formulating a sampling strategy as well as for interpreting the collected data.
Received: 7 December 2001 Accepted: 24 February 2002 相似文献
160.
邓海波 《沈阳大学学报:自然科学版》2005,17(5):12-14
论述了跨国公司在我国的研发活动概况,分析了跨国公司加大在华的研发力度,增设研发机构,与一流的大学和科研院所开展项目合作等活动对我国产生的种种利弊,提出了既要肯定和鼓励跨国公司在华投资的R&D活动,又要持谨慎的态度,加强管理,确保国家安全。 相似文献