全文获取类型
收费全文 | 4251篇 |
免费 | 332篇 |
国内免费 | 2篇 |
专业分类
4585篇 |
出版年
2023年 | 16篇 |
2022年 | 41篇 |
2021年 | 78篇 |
2020年 | 48篇 |
2019年 | 55篇 |
2018年 | 68篇 |
2017年 | 70篇 |
2016年 | 120篇 |
2015年 | 189篇 |
2014年 | 206篇 |
2013年 | 242篇 |
2012年 | 310篇 |
2011年 | 318篇 |
2010年 | 189篇 |
2009年 | 190篇 |
2008年 | 245篇 |
2007年 | 233篇 |
2006年 | 211篇 |
2005年 | 198篇 |
2004年 | 188篇 |
2003年 | 194篇 |
2002年 | 152篇 |
2001年 | 86篇 |
2000年 | 77篇 |
1999年 | 66篇 |
1998年 | 54篇 |
1997年 | 38篇 |
1996年 | 44篇 |
1995年 | 22篇 |
1994年 | 28篇 |
1993年 | 35篇 |
1992年 | 28篇 |
1991年 | 19篇 |
1990年 | 34篇 |
1989年 | 22篇 |
1988年 | 31篇 |
1987年 | 29篇 |
1986年 | 21篇 |
1985年 | 31篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1982年 | 33篇 |
1981年 | 18篇 |
1980年 | 25篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1976年 | 17篇 |
1974年 | 24篇 |
1972年 | 18篇 |
1971年 | 13篇 |
排序方式: 共有4585条查询结果,搜索用时 10 毫秒
51.
Karlsson G 《Protein expression and purification》2003,27(1):171-174
The major active form of human thrombin, alpha-thrombin, was analyzed by hydrophobic interaction high-performance liquid chromatography (HIC-HPLC). The chromatographic system included a polymeric phenyl column and elution was performed by a gradient, 2-0M sodium chloride (5-20 min). Total analysis time was 30 min per injection. By this method, a good resolution between alpha-thrombin and the proteolytically modified thrombin forms, beta- and gamma-thrombin, was obtained. In addition, the thrombin preforms, prothrombin, prethrombin 1, and prethrombin 2, were also resolved from alpha-thrombin in the system. The results from the HIC method were compared to those obtained from non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By this high-resolution chromatographic method, the rapid analysis of purified alpha-thrombin is possible. 相似文献
52.
53.
54.
55.
Sebastian Wacker Bjørn Mejdell Larsen Per Jakobsen Sten Karlsson 《Ecology and evolution》2018,8(16):8126-8134
Multiple paternity is an important characteristic of the genetic mating system and common across a wide range of taxa. Multiple paternity can increase within‐population genotypic diversity, allowing selection to act on a wider spectre of genotypes, and potentially increasing effective population size. While the genetic mating system has been studied in many species with active mating behavior, little is known about multiple paternity in sessile species releasing gametes into the water. In freshwater mussels, males release sperm into the water, while eggs are retained and fertilized inside the female (spermcast mating). Mature parasitic glochidia are released into the water and attach to the gills of fish where they are encapsulated until settling in the bottom substrate. We used 15 microsatellite markers to detect multiple paternity in a wild population of the freshwater pearl mussel (Margaritifera margaritifera). We found multiple paternity in all clutches for which more than two offspring were genotyped, and numbers of sires were extremely high. Thirty‐two sires had contributed to the largest clutch (43 offspring sampled). This study provides the first evidence of multiple paternity in the freshwater pearl mussel, a species that has experienced dramatic declines across Europe. Previous studies on other species of freshwater mussels have detected much lower numbers of sires. Multiple paternity in freshwater pearl mussels may be central for maintaining genetic variability in small and fragmented populations and for their potential to recover after habitat restoration and may also be important in the evolutionary arms race with their fish host with a much shorter generation time. 相似文献
56.
Tobias Ruck Stefanie Bock Steffen Pfeuffer Christina B.Schroeter Derya Cengiz Paul Marciniak Maren Lindner Alexander Herrmann Marie Liebmann Stjepana Kovac Lukas Gola Leoni Rolfes Marc Pawlitzki Nils Opel Tim Hahn Udo Dannlowski Thomas Pap Felix Luessi Julian A.Schreiber Bernhard Wünsch Tanja Kuhlmann Guiscard Seebohm Bjrn Tackenberg Patricia Seja Frank Dring Erhard Wischmeyer Achmet Imam Chasan Johannes Roth Luisa Klotz Gerd Meyer zu Hrste Heinz Wiendl Tobias Marschall Stefan Floess Jochen Huehn Thomas Budde Tobias Bopp Stefan Bittner Sven G.Meuth 《Cell research》2022,32(1):72-88
It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that driv... 相似文献
57.
AbstractEtheno–DNA adducts are generated from exogenous carcinogens such as vinyl chloride and urethane and also from endogenous lipid peroxidation products such as trans-4-hydroxy-2-nonenal (HNE). The present authors and others have established that 1,N6-ethenodeoxyadenosine (εdA) and 3,N4-ethenodeoxycytidine (εdC) are present in human urine and could be explored as biomarkers for monitoring whole-body oxidative stress. The present study reports on a new ultrasensitive 32P-postlabelling/thin-layer chromatography (TLC) method for the analysis of εdC as deoxynucleoside in human urine. The urine samples were purified and enriched on a solid-phase silica C-18 column followed by a semi-preparative reverse-phase high-performance liquid chromatography. The purified sample was labelled with a multisubstrate deoxyribonucleoside kinase from Drosophila melanogaster (Dm-dNK) in the presence of 5′-bromo-2′-deoxyuridine (BrdU) as internal standard. The absolute sensitivity of the method was 0.1 fmol εdC detectable in 500 µl of human urine. The analysis of human urine samples from 15 healthy volunteers revealed a mean εdC level of 2.49±1.76 (SD) fmol µmol?1 creatinine (range 0.66–6.42). By this non-invasive method, εdC in human urine could be explored as a biomarker for oxidative stress-related human diseases. 相似文献
58.
59.
Schumacher J Otte AC Becker T Sun Y Wienker TF Wirth B Franke P Abou Jamra R Propping P Deckert J Nöthen MM Cichon S 《Human genetics》2003,114(1):115-117
A duplication of chromosome 15q24-q26 (DUP25) has been reported to be associated with anxiety disorders. We tested for the presence of DUP25 in a sample of 50 patients with panic disorder and 50 controls using a quantitative real-time PCR approach. Contrary to the original finding, our results were compatible with the absence of DUP25, and no significant difference could be detected between patients and controls (P=1.0). Thus, our study does not support the hypothesis of an involvement of DUP25 in panic disorder. 相似文献
60.