全文获取类型
收费全文 | 133403篇 |
免费 | 3075篇 |
国内免费 | 1343篇 |
专业分类
电工技术 | 2416篇 |
综合类 | 378篇 |
化学工业 | 15779篇 |
金属工艺 | 6256篇 |
机械仪表 | 3903篇 |
建筑科学 | 2963篇 |
矿业工程 | 301篇 |
能源动力 | 3606篇 |
轻工业 | 10369篇 |
水利工程 | 926篇 |
石油天然气 | 801篇 |
武器工业 | 24篇 |
无线电 | 17558篇 |
一般工业技术 | 27255篇 |
冶金工业 | 32640篇 |
原子能技术 | 1579篇 |
自动化技术 | 11067篇 |
出版年
2023年 | 529篇 |
2022年 | 747篇 |
2021年 | 1369篇 |
2020年 | 1062篇 |
2019年 | 1145篇 |
2018年 | 2086篇 |
2017年 | 1937篇 |
2016年 | 2159篇 |
2015年 | 1760篇 |
2014年 | 2468篇 |
2013年 | 6590篇 |
2012年 | 3992篇 |
2011年 | 5264篇 |
2010年 | 4326篇 |
2009年 | 4875篇 |
2008年 | 5210篇 |
2007年 | 5321篇 |
2006年 | 4559篇 |
2005年 | 4021篇 |
2004年 | 3703篇 |
2003年 | 3524篇 |
2002年 | 3109篇 |
2001年 | 3343篇 |
2000年 | 3046篇 |
1999年 | 3560篇 |
1998年 | 11752篇 |
1997年 | 7548篇 |
1996年 | 5749篇 |
1995年 | 3763篇 |
1994年 | 3271篇 |
1993年 | 3161篇 |
1992年 | 1814篇 |
1991年 | 1781篇 |
1990年 | 1678篇 |
1989年 | 1504篇 |
1988年 | 1332篇 |
1987年 | 1033篇 |
1986年 | 1039篇 |
1985年 | 1141篇 |
1984年 | 993篇 |
1983年 | 874篇 |
1982年 | 837篇 |
1981年 | 861篇 |
1980年 | 749篇 |
1979年 | 609篇 |
1978年 | 526篇 |
1977年 | 764篇 |
1976年 | 1466篇 |
1975年 | 398篇 |
1973年 | 372篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Dr. Sandra Liebscher Dr. Sebastian Mathea Dr. Tobias Aumüller Dr. Andreas Pech Prof. Dr. Frank Bordusa 《Chembiochem : a European journal of chemical biology》2021,22(7):1201-1204
Fluorescent fusion proteins are powerful tools for studying biological processes in living cells, but universal application is limited due to the voluminous size of those tags, which might have an impact on the folding, localization or even the biological function of the target protein. The designed biocatalyst trypsiligase enables site-directed linkage of small-sized fluorescence dyes on the N terminus of integral target proteins located in the outer membrane of living cells through a stable native peptide bond. The function of the approach was tested by using the examples of covalent derivatization of the transmembrane proteins CD147 as well as the EGF receptor, both presented on human HeLa cells. Specific trypsiligase recognition of the site of linkage was mediated by the dipeptide sequence Arg-His added to the proteins’ native N termini, pointing outside the cell membrane. The labeling procedure takes only about 5 minutes, as demonstrated for couplings of the fluorescence dye tetramethyl rhodamine and the affinity label biotin as well. 相似文献
12.
Kamar M. S. Shalan A. S. Youssef W. M. Hussein A. E. M. Khawassek Y. M. Taha M. H. 《Radiochemistry》2022,64(2):244-256
Radiochemistry - Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones... 相似文献
13.
Ib Holzmeister Jan Weichhold Jürgen Groll Hala Zreiqat Uwe Gbureck 《Journal of the American Ceramic Society》2021,104(7):3554-3561
In this study, the hydraulic reactivity and cement formation of baghdadite (Ca3ZrSi2O9) was investigated. The material was synthesized by sintering a mixture of CaCO3, SiO2, and ZrO2 and then mechanically activated using a planetary mill. This leads to a decrease in particle and crystallite size and a partial amorphization of baghdadite as shown by X-ray powder diffraction (XRD) and laser diffraction measurements. Baghdadite cements were formed by the addition of water at a powder to liquid ratio of 2.0 g/ml. Maximum compressive strengths were found to be ~2 MPa after 3-day setting for a 24-h ground material. Inductively coupled plasma mass spectrometry (ICP-MS) measurements showed an incongruent dissolution profile of set cements with a preferred dissolution of calcium and only marginal release of zirconium ions. Cement formation occurs under alkaline conditions, whereas the unground raw powder leads to a pH of 11.9 during setting, while prolonged grinding increased pH values to approximately 12.3. 相似文献
14.
Journal of Low Temperature Physics - This study modeled and investigated the magnetocaloric effect in Ni2MnGa Heusler alloy characterized by its magnetic entropy change (ΔSm) and its... 相似文献
15.
Jennie O'Loughlin Silvia Napolitano Fahad Alkhathami Cillian O'Beirne Daniel Marhöfer Megan O'Shaughnessy Prof. Orla Howe Prof. Matthias Tacke Dr. Marina Rubini 《Chembiochem : a European journal of chemical biology》2021,22(6):1093-1098
Antibiotic resistance is a growing problem for public health and associated with increasing economic costs and mortality rates. Silver and silver-related compounds have been used for centuries due to their antimicrobial properties. In this work, we show that 1,3-dibenzyl-4,5-diphenyl-imidazol-2-ylidene silver(I) acetate/NHC*-Ag-OAc (SBC3) is a reversible, high affinity inhibitor of E. coli thioredoxin reductase (TrxR; Ki=10.8±1.2 nM). Minimal inhibition concentration (MIC) tests with different E. coli and P. aeruginosa strains demonstrated that SBC3 can efficiently inhibit bacterial cell growth, especially in combination with established antibiotics like gentamicin. Our results show that SBC3 is a promising antibiotic drug candidate targeting bacterial TrxR. 相似文献
16.
Ava Kwong Cecilia Y. S. Ho Vivian Y. Shin Chun Hang Au Tsun Leung Chan Edmond S. K. Ma 《International journal of molecular sciences》2021,22(2)
The germline carrier of the BRCA1 pathogenic mutation has been well proven to confer an increased risk of breast and ovarian cancer. Despite BRCA1 biallelic pathogenic mutations being extremely rare, they have been reported to be embryonically lethal or to cause Fanconi anemia (FA). Here we describe a patient who was a 48-year-old female identified with biallelic pathogenic mutations of the BRCA1 gene, with no or very subtle FA-features. She was diagnosed with ovarian cancer and breast cancer at the ages of 43 and 44 and had a strong family history of breast and gynecological cancers. 相似文献
17.
World Wide Web - Rule mechanism has been widely used in many areas, such as databases, artificial intelligent and pervasive computing. In a rule mechanism, rule activation decides which rules are... 相似文献
18.
Christoph Gottschalk Aiko Huckauf Arne Dübecke Florian Kaltner Matthias Zimmermann Ines Rahaus 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2018,35(7):1366-1383
The contamination of honey with hepatotoxic pyrrolizidine alkaloids (PAs) is a well-known hazard for food safety. While management strategies and controls of the honey industry aim to reduce the PA levels, uncertainties remain with regard to the safety of regionally produced and marketed honey. In addition, a previous study showed large differences of results obtained after various periods of storage and apparent differences between the analytical results of different laboratories. Therefore, this study aimed at examining these uncertainties by monitoring the impact of storage on the PA and PA N-oxide (PANO) content of two freshly harvested honeys and on possible demixing effects caused by pollen settling. Additionally, three analytical approaches – target analysis with matrix-matched calibration or standard addition and a sum parameter method – were applied for a comparative analysis of 20 honeys harvested in summer 2016. All samples originated from Schleswig-Holstein in Northern Germany where the PA plant Jacobaea vulgaris is currently observed on a massive scale. The results of the time series analyses showed that PANO levels markedly decreased within a few weeks and practically reached the LOD 16 weeks after harvest. Tertiary PAs, by contrast, remained stable and did not increase as a consequence of PANO decrease. The experiments on a putative demixing, which may result in a heterogeneous distribution of PAs/PANOs, revealed that there was no such effect during storage of up to 12 weeks. A comparison of the PA/PANO levels obtained by different analytical approaches showed that in some cases the sum parameter method yielded much higher levels than the target approaches, whereas in other cases, the target analysis with standard addition found higher levels than the other two methods. In summary, the results of this study highlight uncertainties regarding the validity and comparability of analytical results and consequently regarding health risk assessment. 相似文献
19.
Nurullah Bulut Bahar Atmaca Gülsün Akdemir Evrendilek Sibel Uzuner 《Journal of Food Safety》2020,40(6):e12855
Seed processing technologies are essential for seed safety and functionality through protection of physicochemical quality, pathogen inactivation, aflatoxin detoxification and alleviation of mutagenicity. Design of a pilot-scale unit of pulsed electric fields (PEF) to treat sesame seeds with respect to quality parameters, Aspergillus parasiticus inactivation and aflatoxin reduction as well as alleviation of aflatoxin mutagenicity were prompted in this study. PEF energy ranged from 0.97 to 17.28 J achieved maximum reductions of peroxide value and acidity number of 67.4 and 85.7%, respectively, and did not change color L*, a*, b* and hue values. A 60% reduction of A. parasiticus counts occurred at the maximum PEF energy. Aflatoxins G1, G2, B1, and B2 contents decreased by 94.7, 92.7, 86.9, and 98.7%, respectively. Except for the samples treated by 2.16 J with 100 μg/plate and by 6.80 J with 10 μg/plate, PEF treatment provided elimination of aflatoxin mutagenity. It is concluded that PEF treatment can be used to treat sesame seeds with preservation of physicochemical properties, inactivation of A. parasiticus and decomposition of aflatoxins with reduced mutagenicity. 相似文献
20.