全文获取类型
收费全文 | 6113篇 |
免费 | 405篇 |
国内免费 | 19篇 |
学科分类
工业技术 | 6537篇 |
出版年
2023年 | 54篇 |
2022年 | 63篇 |
2021年 | 172篇 |
2020年 | 146篇 |
2019年 | 157篇 |
2018年 | 267篇 |
2017年 | 247篇 |
2016年 | 252篇 |
2015年 | 229篇 |
2014年 | 335篇 |
2013年 | 645篇 |
2012年 | 390篇 |
2011年 | 521篇 |
2010年 | 402篇 |
2009年 | 342篇 |
2008年 | 212篇 |
2007年 | 193篇 |
2006年 | 116篇 |
2005年 | 142篇 |
2004年 | 105篇 |
2003年 | 95篇 |
2002年 | 131篇 |
2001年 | 101篇 |
2000年 | 77篇 |
1999年 | 59篇 |
1998年 | 81篇 |
1997年 | 74篇 |
1996年 | 59篇 |
1995年 | 53篇 |
1994年 | 46篇 |
1993年 | 41篇 |
1992年 | 35篇 |
1991年 | 31篇 |
1990年 | 22篇 |
1989年 | 28篇 |
1988年 | 21篇 |
1986年 | 21篇 |
1985年 | 32篇 |
1984年 | 42篇 |
1983年 | 37篇 |
1982年 | 30篇 |
1981年 | 44篇 |
1980年 | 34篇 |
1979年 | 39篇 |
1978年 | 37篇 |
1977年 | 29篇 |
1976年 | 53篇 |
1975年 | 27篇 |
1974年 | 25篇 |
1973年 | 36篇 |
排序方式: 共有6537条查询结果,搜索用时 15 毫秒
11.
Qiuping Wang Bojan Šarkanj Jasna Jurasovic Yusuf Chisti Michael Sulyok Jiashun Gong Sarote Sirisansaneeyakul Draženka Komes 《International Journal of Food Science & Technology》2019,54(5):1541-1549
Theabrownins (TB) are polymeric phenolic compounds associated with the multiple bioactivities of Pu-erh tea, a post-fermented Chinese dark tea. High-TB instant Pu-erh tea was produced via a novel submerged fermentation (SF) using Aspergillus tubingensis and compared with samples produced commercially via the conventional solid-state fermentation (SSF). Viable microorganisms and microbial toxins, especially aflatoxins B1, G1, B2, G2, cyclopiazonic acid, fumonisins B1, B2, B3 and ochratoxin A, were below the detection limit in all samples. Fewer microbial metabolites were found in SF instant tea compared with the SSF teas. Based on an adult consuming 1 g of instant Pu-erh tea daily, the dietary intake of investigated elements was below the safe limits recommended by various authorities. Tasters viewed the instant tea infusions as very mild, smooth, mellow and full. This suggested that submerged fermentation using A. tubingensis offers a speedy and safe alternative to commercial production of instant Pu-erh tea. 相似文献
12.
Alfredo M. Gravagnuolo Eden Morales‐Narváez Charlene Regina Santos Matos Sara Longobardi Paola Giardina Arben Merkoçi 《Advanced functional materials》2015,25(38):6084-6092
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications. 相似文献
13.
14.
15.
Ivan Fortelný Monika Lapčíková František Lednický Zdeněk Starý Zdeněk Kruliš 《Polymer Engineering and Science》2008,48(3):564-571
This article is focused on the phase structure development in immiscible polymer blends during melt mixing. Nonuniformity of the phase structure, i.e., the coexistence of areas containing particles with markedly different size distribution, was detected in quenched and compression molded samples of a number of various blends prepared by long and intensive mixing in the chamber of a Plasticorder. The same effect was found also for polystyrene/polyamide blends prepared in a twin‐screw extruder. It was shown that neglecting nonuniformity of the phase structure can lead to considerable error in evaluation of the effect of system parameters on the blend morphology. The reasons for the effect were discussed and it was found that inhomogeneous flow field in mixers is a plausible explanation of the nonuniform phase structure. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
16.
Ohne Zusammenfassung 相似文献
17.
Mariana Ušáková Jozef Lukáč Rastislav Dosoudil Vladimír Jančárik Anna Grusková Elemír Ušák Jozef Sláma Jan Šubrt 《Journal of Materials Science: Materials in Electronics》2007,18(12):1183-1189
The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology.
The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed
by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and
possible applications of such materials. A strong correlation between the substituent content and resulting properties has
been observed, thus allowing preparation of material with the properties tailored for any particular application. 相似文献
18.
Novolac-type polycondensation of benzaldehyde (B) and pyrogallol (P) has been carried out at 60°C, 75°C and 90°C and at B/P mole ratios of 1.5 and 3.0 using phosphoric acid as catalyst. The reaction follows a 2nd order rate law. By using GC consumption data of benzaldehyde and pyrogallol, kinetic parameters such as the overall rate constants, activation energies (Ea) and logA values are investigated. The activation energies for 1.5 and 3.0 B/P mole ratios are found as 62.3 kJ mol?1 and 56.4 kJ mol?1, respectively. The molecular weights of the resins determined by measuring intrinsic viscosities (25°C, THF) are in the range of 0.03 to 0.07 dL g?1 at various temperatures and B/P mole ratios. 相似文献
19.
What are the key elements of a sustainable university? 总被引:1,自引:0,他引:1
Nowadays, the principles of sustainable development are becoming increasingly important and universities are acting as agents
in promoting these principles within society. In the future, universities will inevitably play crucial role in propagating
these principles. This paper highlights important documents and discusses definitions of the term education for sustainable development. Elements, based on continuous feedback loop (Deming spiral) are discussed, in order to incorporate sustainability principles
into university activities. The University of Maribor has been used as a case study to test the effectiveness of the proposed
integration of sustainable development principles. 相似文献
20.
Jiři Gregor 《Mathematics of Control, Signals, and Systems (MCSS)》1991,4(2):205-215
A significant part of the theory of one-dimensional linear shift-invariant systems is based on the concept of weighting function
(or impulse response): the output is the convolution of the weighting function with the input. This paper introduces the concept
of linear translation-invariant systems and uses this notion in studying impulse response, z-transforms, and transfer functions
for multidimensional systems. 相似文献