全文获取类型
收费全文 | 14759篇 |
免费 | 1139篇 |
国内免费 | 10篇 |
出版年
2021年 | 158篇 |
2020年 | 113篇 |
2019年 | 146篇 |
2018年 | 197篇 |
2017年 | 197篇 |
2016年 | 262篇 |
2015年 | 448篇 |
2014年 | 468篇 |
2013年 | 688篇 |
2012年 | 869篇 |
2011年 | 747篇 |
2010年 | 557篇 |
2009年 | 459篇 |
2008年 | 680篇 |
2007年 | 669篇 |
2006年 | 665篇 |
2005年 | 642篇 |
2004年 | 629篇 |
2003年 | 660篇 |
2002年 | 634篇 |
2001年 | 185篇 |
2000年 | 141篇 |
1999年 | 172篇 |
1998年 | 208篇 |
1997年 | 185篇 |
1996年 | 183篇 |
1995年 | 180篇 |
1994年 | 150篇 |
1993年 | 181篇 |
1992年 | 150篇 |
1991年 | 163篇 |
1990年 | 145篇 |
1989年 | 130篇 |
1988年 | 148篇 |
1987年 | 140篇 |
1986年 | 118篇 |
1985年 | 161篇 |
1984年 | 191篇 |
1983年 | 168篇 |
1982年 | 164篇 |
1981年 | 176篇 |
1980年 | 139篇 |
1979年 | 126篇 |
1978年 | 146篇 |
1977年 | 123篇 |
1976年 | 102篇 |
1975年 | 120篇 |
1974年 | 99篇 |
1973年 | 96篇 |
1970年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
11.
12.
Jan Batelka Jakub Prokop Hans Pohl Ming Bai Weiwei Zhang Rolf G. Beutel 《Systematic Entomology》2019,44(2):396-407
Extremely miniaturized longipedes insects (body length c. 0.3 mm) embedded in two pieces of Cretaceous amber from Myanmar are described and interpreted. Using inverted fluorescence and light microscopy for detailed analysis of microstructures, the inclusions were identified as primary larvae of the beetle family Ripiphoridae, subfamily Ripidiinae. While the structure of thoracic and abdominal segments including appendages corresponds well with the groundplan known in recent members of Ripidiinae, a curved prosternal ridge with prominent spines (each c. 5 μm), the reduced condition of stemmata and antennae and the lack of sharp mandibles are unique features within the entire family, apparently apomorphies of the longipedes larvae. A sinuate prosternal edge with a dense row of spines (prosternoctenidium) might be homologous with ‘head ctenidia’ in some previously described miniaturized conicocephalate larvae, but further investigation is needed. The morphological differences between the head of longipedes larvae and extant Ripidiinae are interpreted as adaptations to different groups of hosts and life strategies. Palaeoethology of the longipedes larvae is briefly discussed. In addition, the systematic placement of conicocephalate larvae from Canadian, Myanmar and Russian Cretaceous ambers, already interpreted by various authors as primary instars within Coleopterida (assigned to either Strepsiptera or to the coleopteran Tenebrionoidea: Ripiphoridae), is discussed. 相似文献
13.
Martin T. R. Kuiper Marijke Holtrop Hans de Vries 《Molecular & general genetics : MGG》1988,213(2-3):519-528
14.
15.
16.
Cornel Schmitt und Hans Stadler 《Journal of Ornithology》1918,66(2):220-234
Ohne ZusammenfassungIII.) Nachtigall, Kuckuck, Tannenmeise.S. Journ. f. Ornithologie 1917, Festschrift für Reichenow. 相似文献
17.
Hans Breider 《Molecular & general genetics : MGG》1935,68(1):265-299
Ohne ZusammenfassungMit 17 Textfiguren 相似文献
18.
Planta - Kulturen vonAspergillus niger, in denen dem Pilz gleichzeitig gestaffelte Mengen von Kali und Phosphat geboten wurden, ergaben, daß dasMitscherlich-Baulesche Wirkungsgesetz der... 相似文献
19.
The signal sequence suffices to direct export of outer membrane protein OmpA of Escherichia coli K-12. 总被引:8,自引:3,他引:5
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We studied whether information required for export is present within the mature form of the Escherichia coli 325-residue outer membrane protein OmpA. We had previously analyzed overlapping internal deletions in the ompA gene, and the results allowed us to conclude that if such information exists it must be present repeatedly within the membrane part of the protein encompassing amino acid residues 1 to 177 (R. Freudl, H. Schwarz, M. Klose, N. R. Movva, and U. Henning, EMBO J. 4:3593-3598, 1985). A deletion which removed the codons for amino acid residues 1 to 229 of the OmpA protein was constructed. In this construct the signal sequence was fused to the periplasmic part of the protein. The resulting protein, designated Pro-OmpA delta 1-229, was processed, and the mature 95-residue protein accumulated in the periplasm. Hence, information required for export does not exist within the OmpA protein. 相似文献
20.