全文获取类型
收费全文 | 3619篇 |
免费 | 216篇 |
国内免费 | 11篇 |
出版年
2023年 | 8篇 |
2022年 | 20篇 |
2021年 | 53篇 |
2020年 | 26篇 |
2019年 | 31篇 |
2018年 | 46篇 |
2017年 | 33篇 |
2016年 | 67篇 |
2015年 | 111篇 |
2014年 | 136篇 |
2013年 | 206篇 |
2012年 | 246篇 |
2011年 | 249篇 |
2010年 | 148篇 |
2009年 | 152篇 |
2008年 | 245篇 |
2007年 | 247篇 |
2006年 | 255篇 |
2005年 | 250篇 |
2004年 | 303篇 |
2003年 | 242篇 |
2002年 | 225篇 |
2001年 | 36篇 |
2000年 | 29篇 |
1999年 | 49篇 |
1998年 | 51篇 |
1997年 | 32篇 |
1996年 | 21篇 |
1995年 | 30篇 |
1994年 | 29篇 |
1993年 | 30篇 |
1992年 | 16篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 21篇 |
1988年 | 18篇 |
1987年 | 7篇 |
1986年 | 16篇 |
1985年 | 10篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1976年 | 5篇 |
1974年 | 7篇 |
1970年 | 8篇 |
1969年 | 4篇 |
排序方式: 共有3846条查询结果,搜索用时 15 毫秒
21.
What causes the aphid 28S rRNA to lack the hidden break? 总被引:1,自引:0,他引:1
22.
23.
24.
Organic-Solvent-Tolerant Bacterium Which Secretes Organic-Solvent-Stable Lipolytic Enzyme 总被引:4,自引:1,他引:3 下载免费PDF全文
A bacterial strain which could be grown in a medium containing organic solvents and which could secrete lipolytic enzyme was isolated. The stability of the lipolytic activity of the supernatant of the culture increased significantly in the presence of organic solvents such as toluene, cyclohexane, ethanol, and acetone. 相似文献
25.
Mami Ohsugi Hideki Yamamura Reiji Semba Hiroyoshi Hidaka 《The Histochemical journal》1994,26(8):641-643
Summary To confirm the possibility that protein kinase C is involved in compaction of mouse embryos, the presence and distribution pattern of Ca2+-dependent subspecies of this enzyme in mouse embryos, before and during compaction, were examined immunocytochemically with three different monoclonal antibodies. These were MC-1a, MC-2a and MC-3a, which selectively interact with the subspecies of the enzyme known as types I, II and III, respectively. Only when embryos were incubated with MC-3a, was immunofluorescence clearly detected in all cells of embryos before and during compaction. This result demonstrates the presence of type III protein kinase C in embryos before and during compaction and suggests the possibility that the type III enzyme may be involved in compaction. No marked differences were found in the distribution pattern of the type III enzyme between embryos examined before and during compaction. 相似文献
26.
Naoko Miyano-Kurosaki Hideki Nakashima Koji Ichiyama Kazuhiko Inazawa Hidenori Tabata Hideyuki Tanabe Kiyotaka Ohnishi Hiroshi Mizusawa Yukako Ohshiro Naoki Yamamoto 《Microbiology and immunology》1994,38(10):813-818
A subclonal cl.1–14 cell was established from a monocytic cell line U937 by a limiting dilution method. The anti-HIV-1 activity of some antiviral compounds was evaluated in HIV-1-infected cl.1–14 cells. The results demonstrated that although AZT was a potent inhibitor of HIV-1 replication in cl.1–14 cells, its 50% effective concentration (EC50) values was 80 times higher than that in HIV-1 infected MT-4 cells; the EC50 of AZT was 0.16 μM and 0.002 μM in cl.1–14 and MT-4 cells, respectively. In contrast, the anti-HIV-1 activity of ddA, ddI and ddC in cl.1–14 cells was comparable to that in MT-4 cells. The antiviral activity of nevirapine, dextran sulfate, curdlan sulfate and T22 did not differ significantly between the cl. 1–14 and MT-4 cells. The antiviral activity of several compounds in the HIV-1-infected cl.1–14 cells was similar to that in the HIV-1jr -fl -infected human peripheral macrophages. Our results suggest that cl.1–14 cell cultures are very useful for estimating antiviral activity and more advantageous than the use of peripheral blood macrophages. 相似文献
27.
Yoshiyuki Kawakami Ichiro Ueno Tsutomu Katsuyama Ken'ichi Furihata Hideki Matsumoto 《Microbiology and immunology》1994,38(11):891-895
Epidemiological typing, based on restriction fragment length polymorphism (RFLP) by pulsed-field gel electrophoresis (PFGE), was attempted for the 38 clinical isolates of Moraxella catarrhalis obtained at Shinshu University Hospital during the years 1987 and 1993. Digestion with SmaI or NotI generated well separable, 12 to 5 genomic DNA fragments ranging from 1,000 kb to 30 kb and the strains could be classified into 14 or 13 types, respectively. The electrophoretic profile differed with the strain in most of them and was hence useful to distinguish the each strain. Investigation for their RFLP have, however, suggested that majority of them, including the type strain ATCC25238, may have derived from a common ancestor. 相似文献
28.
Hideki Takahashi 《Journal of plant research》1994,107(3):237-243
Trillium apetalon Makino is unique amongTrillium in having apetalous flowers. Using scanning electron microscope, the early floral development was observed in comparison
with that ofT. kamtschaticum Pallas ex Pursh having petalous flowers. Morphologically petal primordia closely resemble stamen primordia in their more
or less narrow and radially symmetric shape and are clearly distinct from sepal primordia with broad bases. Early in floral
development sepal primordia are first initiated and subsequently two whorls of three primordia each are formed in rapid sequence,
the first three at the corners and the second three at the sides of the triangular floral apex. Based on comparison in position
and early developmental processes of their primordia, petals and outer stamens ofTrillium kamtschaticum are equivalent to outer stamens and inner stamens ofT. apetalon. The replacement of petals by outer stamens apparently leads to the loss of petals inTrillium apetalon flowers. Such a replacement can be interpreted in terms of homeosis. The replacement of the petal whorl leads to the serial
replacement of the subsequent whorls: outer stamens by inner stamens, and inner stamens by gynoecium inTrillium apetalon. The term ‘serial homeosis’ is introduced for this serial replacement. 相似文献
29.
Zenjiro Osawa Tsubura Morota Kenichi Hatanaka Toshihiro Akaike Kei Matsuzaki Hideki Nakashima Naoki Yamamoto Eiichiro Suzuki Hiroshi Miyano Tohru Mimura Yutaro Kaneko 《Carbohydrate polymers》1993,21(4):283-288
Sulfopropyl curdlan was synthesized, its structure was determined, and the anti-HIV activity was compared with that of standard curdlan sulfates obtained with piperidine N-sulfonic acid in dimethyl sulfoxide. It was shown that sulfopropyl curdlan exhibits weaker anti-HIV activity than curdlan sulfate. Curdlan sulfates were synthesized with a SO3-pyridine complex in a heterogeneous phase. It was shown from 13C-NMR spectra of acetylated curdlan sulfates that they had a different substituent distribution from standard curdlan sulfate. The cytotoxicity of the curdlan sulfates was attributed to their heterogeneous structure. 相似文献
30.
Hideaki Sato Hideki Hirayama Takeshi Yamamoto Yoshimasa Lchio Fumiaki Ishizawa Michinao Mizugaki 《Luminescence》1994,9(2):73-77
The purpose of the study was to evaluate the quality of Toki-shakuyaku-san extract granules (TJ-23) using chemiluminescence (CL). A linear relationship was obtained between the log value of the CL of TJ-23 and the reaction temperature. An excellent correlation (r= 0.999) was found between the slope of this curve (ΔA) and the colour intensity due to the browning reaction occurring at the early stage of the Maillard reaction. 相似文献