全文获取类型
收费全文 | 6807篇 |
免费 | 99篇 |
国内免费 | 27篇 |
专业分类
化学 | 3807篇 |
晶体学 | 36篇 |
力学 | 170篇 |
数学 | 961篇 |
物理学 | 1959篇 |
出版年
2020年 | 52篇 |
2019年 | 52篇 |
2016年 | 88篇 |
2015年 | 70篇 |
2014年 | 84篇 |
2013年 | 305篇 |
2012年 | 215篇 |
2011年 | 264篇 |
2010年 | 159篇 |
2009年 | 149篇 |
2008年 | 245篇 |
2007年 | 302篇 |
2006年 | 290篇 |
2005年 | 293篇 |
2004年 | 284篇 |
2003年 | 223篇 |
2002年 | 200篇 |
2001年 | 156篇 |
2000年 | 153篇 |
1999年 | 92篇 |
1998年 | 87篇 |
1997年 | 99篇 |
1996年 | 117篇 |
1995年 | 81篇 |
1994年 | 103篇 |
1993年 | 107篇 |
1992年 | 139篇 |
1991年 | 100篇 |
1990年 | 102篇 |
1989年 | 91篇 |
1988年 | 71篇 |
1987年 | 85篇 |
1986年 | 82篇 |
1985年 | 142篇 |
1984年 | 126篇 |
1983年 | 106篇 |
1982年 | 98篇 |
1981年 | 99篇 |
1980年 | 107篇 |
1979年 | 87篇 |
1978年 | 101篇 |
1977年 | 100篇 |
1976年 | 79篇 |
1975年 | 86篇 |
1974年 | 108篇 |
1973年 | 113篇 |
1972年 | 78篇 |
1971年 | 62篇 |
1970年 | 52篇 |
1969年 | 54篇 |
排序方式: 共有6933条查询结果,搜索用时 62 毫秒
71.
72.
Henriques ES Floriano WB Reuter N Melo A Brown D Gomes JA Maigret B Nascimento MA Ramos MJ 《Journal of computer-aided molecular design》2001,15(4):309-322
We present the search for a new model of -factor XIIa, a blood coagulation enzyme, with an unknown experimental 3D-structure. We decided to build not one but three different models using different homologous proteins as well as different techniques and different modellers. Additional studies, including extensive molecular dynamics simulations on the solvated state, allowed us to draw several conclusions concerning homology modelling, in general, and -factor XIIa, in particular. 相似文献
73.
Li C Lee D Graf TN Phifer SS Nakanishi Y Burgess JP Riswan S Setyowati FM Saribi AM Soejarto DD Farnsworth NR Falkinham JO Kroll DJ Kinghorn AD Wani MC Oberlies NH 《Organic letters》2005,7(25):5709-5712
[chemical reaction: see text]. Three new ent-trachylobane diterpenoids (1-3) were isolated and structures elucidated from Mitrephora glabra Scheff. (Annonaceae). Mitrephorone A (1) possesses a hexacyclic ring system with adjacent ketone moieties and an oxetane ring, both of which are unprecedented among trachylobanes. All compounds were evaluated for cytotoxicity against a panel of cancer cells, where 1 displayed the most potent and broadest activity, and against a battery of antimicrobial assays, where all compounds were approximately equipotent. 相似文献
74.
M. E. Brown M. J. Tribelhorn M. G. Blenkinsop 《Journal of Thermal Analysis and Calorimetry》1993,40(3):1123-1130
Thermal analysis is routinely used to characterize pyrotechnic fuels, oxidants and fuel/oxidant mixtures [1]. Thermomagnetometry (TM) can provide additional information if the magnetic properties of the materials change during reaction. TG, TM and DTA results for the iron/potassium permanganate, iron/barium peroxide, and iron/strontium peroxide systems as loose powders or pressed pellets indicate predominantly solid-gas mechanisms for reactions in these systems. 相似文献
75.
In a previous paper, some 15 compounds were positively identified among the products of thermal degradation of bisphenol-A diglycidyl ether. The structures of an additional 22 compounds, all aromatic, were speculated upon on the basis of mass spectral analysis. In the present paper, mechanisms are proposed to account for all these products and the characteristics of their formation in the overall degradation process. 相似文献
76.
77.
78.
Blaylock GT Bolton T Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Dorfan DE Dubois GP Eigen G Eisenstein BI Freese T Gladding G Grab C Heusch CA Hitlin DG Izen JM Köpke L Li A Lockman WS Mallik U Matthews CG Mir R Mockett PM Mozley RF Nemati B Odian A Parker J Parrish L Partridge R Pitman D Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Simopoulos C Stockdale IE Stockhausen W Thaler JJ Toki W Tripsas B Villa F Wasserbaech S Wattenberg A Weinstein AJ 《Physical review letters》1987,58(21):2171-2174
79.
S. F. Biagi M. Bourquin R. M. Brown H. J. Burckhart P. Extermann M. Gailloud C. N. P. Gee W. M. Gibson P. Jacot-Guillarmod J. Perrier K. J. Ragan Ph. Rosselet P. Schirato H. W. Siebert V. J. Smith K. P. Streit J. J. Thresher A. T. Wood C. Yanagisawa 《Zeitschrift fur Physik C Particles and Fields》1987,34(2):175-185
In an experiment at the CERN-SPS charged hyperon beam, we have investigated the inclusive \(\Lambda \bar K^0 \) and \(\Sigma ^0 \bar K^0 \) final states formed in Ξ? Be interactions. In the \(\Lambda \bar K^0 \) channel, we observe a signal at 1826 MeV/c2 which can be identified with the known Ξ(1820) resonance. We determine its mass and width to be:M=1826±4 MeV/c2, Г=12±14 MeV/c2. A moment analysis is consistent with a spin of 3/2 and indicates a negative parity for this spin assignment. Also in the \(\Lambda \bar K^0 \) channel, we observe a 3.6σ signal with the following parameters:M=1963±5 MeV/c2, Г=25±15 MeV/c2. This state, which we call Ξ(1960), is not observed in the \(\Sigma ^0 \bar K^0 \) channel, leading to an upper limit on the ratio of partial widths \(\Sigma \bar K/\Lambda \bar K\) of 2.3 (90% confidence level). A moment analysis of the \(\Lambda \bar K^0 \) final state indicates a spin of 5/2 or greater in the natural spin-parity series 5/2+, 7/2?, etc. 相似文献
80.