全文获取类型
收费全文 | 523篇 |
免费 | 7篇 |
专业分类
化学 | 262篇 |
晶体学 | 6篇 |
力学 | 12篇 |
数学 | 19篇 |
物理学 | 231篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2020年 | 10篇 |
2018年 | 3篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 24篇 |
2012年 | 21篇 |
2011年 | 33篇 |
2010年 | 11篇 |
2009年 | 11篇 |
2008年 | 25篇 |
2007年 | 24篇 |
2006年 | 30篇 |
2005年 | 22篇 |
2004年 | 23篇 |
2003年 | 21篇 |
2002年 | 15篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1966年 | 2篇 |
1958年 | 2篇 |
1928年 | 2篇 |
1917年 | 2篇 |
排序方式: 共有530条查询结果,搜索用时 15 毫秒
31.
The focused ion beam lift-out technique for scanning electron microscope (SEM) and transmission electron microscope (TEM) sample preparation was shown to be applicable to copper/low-k dielectric semiconductor technology. High resolution SEM, TEM, and scanning transmission electron microscope analyses were performed on metal contacts and resist vias with no evidence of the interface damage or metal smearing commonly observed with mechanical polishing. Ion milling of the sample ex situ to the substrate provided decoration and adjustment of the exposed plane of the section when necessary for SEM analysis. 相似文献
32.
Dr. Zahra Rashidijahanabad Prof. Dr. Sherif Ramadan Nicholas A. O'Brien Athar Nakisa Dr. Shuyao Lang Dr. Howard Crawford Dr. Jeffrey C. Gildersleeve Prof. Dr. Xuefei Huang 《Angewandte Chemie (International ed. in English)》2023,62(47):e202309744
Sialyl Lewisa (sLea), also known as cancer antigen 19-9 (CA19-9), is a tumor-associated carbohydrate antigen. The overexpression of sLea on the surface of a variety of cancer cells makes it an attractive target for anticancer immunotherapy. However, sLea-based anticancer vaccines have been under-explored. To develop a new vaccine, efficient stereoselective synthesis of sLea with an amine-bearing linker was achieved, which was subsequently conjugated with a powerful carrier bacteriophage, Qβ. Mouse immunization with the Qβ-sLea conjugate generated strong and long-lasting anti-sLea IgG antibody responses, which were superior to those induced by the corresponding conjugate of sLea with the benchmark carrier keyhole limpet hemocyanin. Antibodies elicited by Qβ-sLea were highly selective toward the sLea structure, could bind strongly with sLea-expressing cancer cells and human pancreatic cancer tissues, and kill tumor cells through complement-mediated cytotoxicity. Furthermore, vaccination with Qβ-sLea significantly reduced tumor development in a metastatic cancer model in mice, demonstrating tumor protection for the first time by a sLea-based vaccine, thus highlighting the significant potential of sLea as a promising cancer antigen. 相似文献
33.
Kathy C. Chuang Daniel A. Scheiman Joyce Fu Marcus Crawford 《Journal of polymer science. Part A, Polymer chemistry》1999,37(14):2559-2567
Thermoplastic and thermoset polyimides derived from 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) and 4,4′-bis(4-aminophenoxy)-2,2′-dimethylbiphenyl (BAPD) were prepared and characterized. Their physical and thermal properties as well as the polyelectrolyte effect exhibited by BTDA–BAPP polyamic acids in NMP solution were discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2559–2567, 1999 相似文献
34.
John T. Gupton Alex Shimozono Evan Crawford Joe Ortolani Evan Clark Matt Mahoney Campbell Heese Jeffrey Noble Carlos Perez Mandry Rene Kanters Raymond N. Dominey Emma W. Goldman James A. Sikorski Daniel C. Fisher 《Tetrahedron》2018,74(21):2650-2663
Highly functionalized pyrroles with appropriate regiochemical functionality represent an important class of marine natural products and potential drug candidates. We describe herein a detailed study of the reaction of α-aminoacid esters with vinylogous amides and also β-halovinylaldehydes for the regiospecific synthesis of 2,3,4-trisubstituted and 1,2,3,4-tetrasubstituted pyrroles. Since the vinylogous amides and β-halovinylaldehydes are readily available precursors, rapid access to a wide variety of unsymmetrically substituted pyrroles is accomplished via this methodology. 相似文献
35.
Dean A. Flinchbaugh L. F. Crawford David Bradley 《Accreditation and quality assurance》2001,6(12):493-500
A model is presented that correlates historical proficiency test data as the log of interlaboratory standard deviations versus
the log of analyte concentrations, independent of analyte (measurand) or matrix. Analytical chemistry laboratories can use
this model to set their internal measurement quality objectives and to apply the uncertainty budget process to assign the
maximum allowable variation in each major step in their bias-free measurement systems. Laboratories that are compliant with
this model are able to pass future proficiency tests and demonstrate competence to laboratory clients and ISO 17025 accreditation
bodies. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/
10.1007/s007690100398-y.
Received: 31 March 2001 Accepted: 11 September 2001 相似文献
36.
We have developed an optical stack of holographically formed polymer dispersed liquid-crystal (H-PDLC) devices that is fully operational with nonpolarized light sources. The device consists of two H-PDLC transmission gratings separated by a passive polarization rotator that can output a diffracted s-polarized, p-polarized, or s- and p-polarized beam simultaneously. 相似文献
37.
Tests involving the cold compaction of four polymeric powders in circular section tapered dies were carried out to study the force transmitted through the powders. It was found that the decreasing cross-sectional area could be used to compensate for the force loss in order to keep the transmitted pressure high but the effect was not as large as had been anticipated. The optimum angle of taper was found to be in the region of 75 to 80°. A mathematical model was developed for the compaction of plastic powders in tapered dies. It was found that an equation of the type could be used to prodict the transmitted pressured in a tapered die from a knowledge of the compaction characteristics for a cylindrical die. 相似文献
38.
Savard G Buchinger F Clark JA Crawford JE Gulick S Hardy JC Hecht AA Lee JK Levand AF Scielzo ND Sharma H Sharma KS Tanihata I Villari AC Wang Y 《Physical review letters》2005,95(10):102501
The masses of the radioactive nuclei (46)V and its decay daughter (46)Ti have been measured with the Canadian Penning Trap on-line Penning trap mass spectrometer to a precision of 1 x 10(-8). A Q(EC) value of 7052.90(40) keV for the superallowed beta decay of (46)V is obtained from the difference of these two masses. With this precise Q value, the Ft value for this decay is determined with improved precision. An investigation of an earlier Q-value measurement for (46)V uncovers a set of 7 measurements that cannot be reconciled with modern data and affects previous evaluations of V(ud) from superallowed Fermi decays. A new evaluation, adding our new data and removing the discredited subset, yields new values for G(V) and V(ud). When combined with recent results for V(us), this yields modified constraints for the unitarity of the Cabibbo-Kobayashi-Maskawa matrix and other extensions of the standard model. 相似文献
39.
Adams J Adler C Aggarwal MM Ahammed Z Amonett J Anderson BD Anderson M Arkhipkin D Averichev GS Badyal SK Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bezverkhny BI Bhardwaj S Bhaskar P Bhati AK Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Botje M Boucham A Brandin A Bravar A Cadman RV Cai XZ Caines H Calderón de la Barca Sánchez M Carroll J Castillo J Castro M Cebra D Chaloupka P Chattopadhyay S Chen HF Chen Y Chernenko SP Cherney M Chikanian A Choi B 《Physical review letters》2004,92(17):171801
Measurements of the production of forward high-energy pi(0) mesons from transversely polarized proton collisions at sqrt[s]=200 GeV are reported. The cross section is generally consistent with next-to-leading order perturbative QCD calculations. The analyzing power is small at x(F) below about 0.3, and becomes positive and large at higher x(F), similar to the trend in data at sqrt[s]< or =20 GeV. The analyzing power is in qualitative agreement with perturbative QCD model expectations. This is the first significant spin result seen for particles produced with p(T)>1 GeV/c at a polarized proton collider. 相似文献
40.
Adams J Aggarwal MM Ahammed Z Amonett J Anderson BD Arkhipkin D Averichev GS Badyal SK Bai Y Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bezverkhny BI Bharadwaj S Bhasin A Bhati AK Bhatia VS Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Botje M Boucham A Brandin AV Bravar A Bystersky M Cadman RV Cai XZ Caines H Calderón de la Barca Sánchez M Carroll J Castillo J Cebra D Chajecki Z Chaloupka P Chattopdhyay S Chen HF Chen Y Cheng J Cherney M Chikanian A 《Physical review letters》2004,93(25):252301
Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au + Au collisions at square root s(NN)=200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au + Au collisions to those in p + p at the same energy. The elliptic anisotropy v(2) is found to reach its maximum at p(t) approximately 3 GeV/c, then decrease slowly and remain significant up to p(t) approximately 7-10 GeV/c. Stronger suppression is found in the back-to-back high-p(t) particle correlations for particles emitted out of plane compared to those emitted in plane. The centrality dependence of v(2) at intermediate p(t) is compared to simple models based on jet quenching. 相似文献