全文获取类型
收费全文 | 8954篇 |
免费 | 234篇 |
国内免费 | 10篇 |
专业分类
化学 | 5325篇 |
晶体学 | 36篇 |
力学 | 166篇 |
数学 | 1501篇 |
物理学 | 2170篇 |
出版年
2020年 | 72篇 |
2019年 | 71篇 |
2017年 | 65篇 |
2016年 | 197篇 |
2015年 | 134篇 |
2014年 | 141篇 |
2013年 | 317篇 |
2012年 | 297篇 |
2011年 | 386篇 |
2010年 | 221篇 |
2009年 | 210篇 |
2008年 | 331篇 |
2007年 | 319篇 |
2006年 | 297篇 |
2005年 | 296篇 |
2004年 | 218篇 |
2003年 | 211篇 |
2002年 | 182篇 |
2001年 | 141篇 |
2000年 | 147篇 |
1999年 | 127篇 |
1998年 | 104篇 |
1997年 | 116篇 |
1996年 | 136篇 |
1995年 | 149篇 |
1994年 | 112篇 |
1993年 | 136篇 |
1992年 | 165篇 |
1991年 | 137篇 |
1990年 | 126篇 |
1989年 | 112篇 |
1988年 | 106篇 |
1987年 | 110篇 |
1986年 | 105篇 |
1985年 | 128篇 |
1984年 | 140篇 |
1983年 | 127篇 |
1982年 | 130篇 |
1981年 | 159篇 |
1980年 | 99篇 |
1979年 | 129篇 |
1978年 | 121篇 |
1977年 | 136篇 |
1976年 | 113篇 |
1975年 | 134篇 |
1974年 | 122篇 |
1973年 | 107篇 |
1972年 | 71篇 |
1967年 | 69篇 |
1962年 | 69篇 |
排序方式: 共有9198条查询结果,搜索用时 158 毫秒
1.
2.
3.
4.
Stefan Peterli Dieter Hubmann Urs Squin Helmut Mett Peter Traxler 《Helvetica chimica acta》1994,77(1):59-69
β-Nitrostyrene derivatives of adenosine 5′-glutarates are potent and selective bisubstrate-type inhibitors of the epidermal growth factor receptor protein tyrosine kinase (EGF-R PTK). In an attempt to improve the inhibitory activity, this type of compounds was modified with alkyl spacers of varying length between the nitrostyrene and the glutaryl units. The spacers consisted of 1, 3, 4, and 5 atoms to give compounds of the benzyl, oxyethyl, oxypropyl, and oxybutyl series, respectively (Schemes 1 and 2). Adenosine 5′-esters were prepared in the benzyl and oxypropyl series only. Compared to the compounds in the parent series without spacer (IC50 = 0.7–12 μM ), most of the modified compounds inhibited the EGF-R PTK only marginally or were inactive (IC50 ≥ 100 μM ). The only exceptions were the free acids 19 and 20 with IC50 values of ca. 5 μM . It is noteworthy that esterification of these two hydrogen glutarates with either MeOH or adenosine yielded inactive compounds, which is in contrast to the corresponding substances without spacers. 相似文献
5.
Helmut Schmidhammer Eva Scherb-Bukowiecki Thomas A. Mayer Peter Schnholzer 《Helvetica chimica acta》1994,77(6):1590-1594
The synthesis of benzazepine analogues of the opium alkaloid noscapine ( 1 ) is described. The benzazepines 2 and 3 were prepared starting from nornarceine ethyl ester ( 4 ; readily available from 1 ) in several steps. X-Ray analysis of compound 2 revealed that it is not a diastereosisomer mixture but a racemate of the threo-form and thus has the same configuration as 1 . 相似文献
6.
J. Maul I. Strachnov S. Karpuk P. Bernhard A. Oelsner G. Schönhense G. Huber 《Applied Physics A: Materials Science & Processing》2006,82(1):43-47
We report morphologic changes of metallic surfaces at the onset of ablation, starting from gentle ablation to the emergence of ablation craters. The evolution of both observed melting zones and of ablation craters therein are investigated in dependence of the ablation laser fluence for nanosecond ultraviolet laser pulses. Further, consequences of crater formation for cluster synthesis within the released atomic vapor are pointed out. PACS 52.38.Mf; 79.20.Ds; 65.40.De 相似文献
7.
The control of piecewise-deterministic processes is studied where only local boundedness of the data is assumed. Moreover the discount rate may be zero. The value function is shown to be solution to the Bellman equation in a weak sense; however the solution concept is strong enough to generate optimal policies. Continuity and compactness conditions are given for the existence of nonrelaxed optimal feedback controls. 相似文献
8.
S. Trebert Haeberlin F. Lux J. Karl T. Spruss H. Schönenberger 《Journal of Radioanalytical and Nuclear Chemistry》1987,113(2):461-467
As part of an examination of the cytostatic effects of 1,2-diarylethylenediamine-platinum(II)-complexes the contents of platinum and biologically essential trace elements of tumour tissue and different organs were determined. The activation analysis procedure — separation of32P, isolation of199Au and99Mo — is described. In the course of a pharmakokinetical experiment with tumourbearing rats (DMBA induced hormone-dependent tumours) the desired enrichment of the administered drug in the tumour tissue was found. Changes of the trace element level of tumour tissue were found for hormone-dependent MXT-mammary tumours on mice. 相似文献
9.
10.
Vlasov Yu. G. Murzina Yu. G. Legin A. V. Ermolenko Yu. E. Schubert J. Schüoning M. J. Lut H. 《Russian Journal of Applied Chemistry》2002,75(3):351-356
Methods of silicon planar technology and pulsed laser deposition were applied to fabricate fully solid-state chemical sensors for determining ions of copper, lead, cadmium, thallium, and also sulfide and chloride ions on the basis of thin chalcogenide films as ion-sensitive membranes. 相似文献