全文获取类型
收费全文 | 24599篇 |
免费 | 1009篇 |
国内免费 | 143篇 |
专业分类
化学 | 17479篇 |
晶体学 | 207篇 |
力学 | 485篇 |
数学 | 3257篇 |
物理学 | 4323篇 |
出版年
2023年 | 175篇 |
2022年 | 152篇 |
2021年 | 332篇 |
2020年 | 485篇 |
2019年 | 471篇 |
2018年 | 316篇 |
2017年 | 277篇 |
2016年 | 731篇 |
2015年 | 622篇 |
2014年 | 749篇 |
2013年 | 1224篇 |
2012年 | 1617篇 |
2011年 | 1791篇 |
2010年 | 1035篇 |
2009年 | 872篇 |
2008年 | 1494篇 |
2007年 | 1408篇 |
2006年 | 1394篇 |
2005年 | 1297篇 |
2004年 | 1124篇 |
2003年 | 827篇 |
2002年 | 684篇 |
2001年 | 260篇 |
2000年 | 237篇 |
1999年 | 202篇 |
1998年 | 213篇 |
1997年 | 291篇 |
1996年 | 300篇 |
1995年 | 267篇 |
1994年 | 295篇 |
1993年 | 286篇 |
1992年 | 249篇 |
1991年 | 180篇 |
1990年 | 212篇 |
1989年 | 179篇 |
1988年 | 188篇 |
1987年 | 172篇 |
1986年 | 160篇 |
1985年 | 273篇 |
1984年 | 259篇 |
1983年 | 178篇 |
1982年 | 201篇 |
1981年 | 184篇 |
1980年 | 181篇 |
1979年 | 170篇 |
1978年 | 195篇 |
1977年 | 181篇 |
1976年 | 136篇 |
1975年 | 135篇 |
1974年 | 157篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Tao Wang Dr. Yuzhou Wu Dr. Seah Ling Kuan Oliver Dumele Dr. Markus Lamla Dr. David Y. W. Ng Matthias Arzt Jessica Thomas Jan O. Mueller Prof. Dr. Christopher Barner‐Kowollik Prof. Dr. Tanja Weil 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):228-238
A disulfide intercalator toolbox was developed for site‐specific attachment of a broad variety of functional groups to proteins or peptides under mild, physiological conditions. The peptide hormone somatostatin (SST) served as model compound for intercalation into the available disulfide functionalization schemes starting from the intercalator or the reactive SST precursor before or after bioconjugation. A tetrazole–SST derivative was obtained that undergoes photoinduced cycloaddition in mammalian cells, which was monitored by live‐cell imaging. 相似文献
32.
Association and Dissociation of Grignard Reagents RMgCl and Their Turbo Variant RMgCl⋅LiCl 下载免费PDF全文
Christoph Schnegelsberg Sebastian Bachmann Marlene Kolter Thomas Auth Dr. Michael John Prof. Dr. Dietmar Stalke Prof. Dr. Konrad Koszinowski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7752-7762
Grignard reagents RMgCl and their so‐called turbo variant, the highly reactive RMgCl?LiCl, are of exceptional synthetic utility. Nevertheless, it is still not fully understood which species these compounds form in solution and, in particular, in which way LiCl exerts its reactivity‐enhancing effect. A combination of electrospray‐ionization mass spectrometry, electrical conductivity measurements, NMR spectroscopy (including diffusion‐ordered spectroscopy), and quantum chemical calculations is used to analyze solutions of RMgCl (R=Me, Et, Bu, Hex, Oct, Dec, iPr, tBu, Ph) in tetrahydrofuran and other ethereal solvents in the absence and presence of stoichiometric amounts of LiCl. In tetrahydrofuran, RMgCl forms mononuclear species, which are converted into trinuclear anions as a result of the concentration increase experienced during the electrospray process. These trinuclear anions are theoretically predicted to adopt open cubic geometries, which remarkably resemble structural motifs previously found in the solid state. The molecular constituents of RMgCl and RMgCl?LiCl are interrelated via Schlenk equilibria and fast intermolecular exchange processes. A small portion of the Grignard reagent also forms anionic ate complexes in solution. The abundance of these more electron‐rich and hence supposedly more nucleophilic ate complexes strongly increases upon the addition of LiCl, thus rationalizing its beneficial effect on the reactivity of Grignard reagents. 相似文献
33.
Anil Arya Clemens Löffler Brian Mittendorf Thomas Pfeiffer 《European Journal of Operational Research》2015
The prevalence of intermediaries (middlemen) in supply chains is often seen as a dying remnant of less efficient times. Despite predictions that supply chains will rapidly “cut out the middleman” as technological advances have eased logistics, middlemen have continued to thrive. In this paper, we demonstrate a transaction role of middlemen that may help clarify their staying power. In a model with self-interested decision-making by both a manufacturer and a retailer, wherein incentive misalignment creates investment and production inefficiencies, we show that the integrated (first-best) outcome can be achieved with simple cost-based contracts if and only if a middleman is present. We further show that the approach of utilizing a middleman to fully coordinate the supply chain is robust in that it can be applied to a variety of circumstances discussed in the literature, including multilateral investment/effort choices, multiple product providers, and logistical investments made by the middleman. 相似文献
34.
35.
36.
37.
38.
Is it True That the Normal Valence‐Length Correlation Is Irrelevant for Metal–Metal Bonds? 下载免费PDF全文
Dr. Vijay Singh Dr. Mudit Dixit Dr. Monica Kosa Prof. Dan Thomas Major Prof. Elena Levi Prof. Dr. Doron Aurbach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5269-5276
The most intriguing feature of metal–metal bonds in inorganic compounds is an apparent lack of correlation between the bond order and the bond length. In this study, we combine a variety of literature data obtained by quantum chemistry and our results based on the empirical bond valence model (BVM), to confirm for the first time the existence of a normal exponential correlation between the effective bond order (EBO) and the length of the metal–metal bonds. The difference between the EBO and the formal bond order is attributed to steric conflict between the (TM)n cluster (TM=transition metal) and its environment. This conflict, affected mainly by structural type, should cause high lattice strains, but electron redistribution around TM atoms, evident from the BVM calculations, results in a full or partial strain relaxation. 相似文献
39.
40.