全文获取类型
收费全文 | 1327篇 |
免费 | 108篇 |
出版年
2021年 | 22篇 |
2020年 | 12篇 |
2019年 | 14篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 21篇 |
2015年 | 46篇 |
2014年 | 34篇 |
2013年 | 115篇 |
2012年 | 82篇 |
2011年 | 66篇 |
2010年 | 52篇 |
2009年 | 50篇 |
2008年 | 51篇 |
2007年 | 66篇 |
2006年 | 67篇 |
2005年 | 77篇 |
2004年 | 55篇 |
2003年 | 52篇 |
2002年 | 66篇 |
2001年 | 48篇 |
2000年 | 49篇 |
1999年 | 27篇 |
1998年 | 23篇 |
1997年 | 14篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 30篇 |
1991年 | 29篇 |
1990年 | 22篇 |
1989年 | 28篇 |
1988年 | 16篇 |
1987年 | 20篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1974年 | 4篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1968年 | 3篇 |
排序方式: 共有1435条查询结果,搜索用时 15 毫秒
1.
A Nicotiana tabacum cell line, KS-1, which is tolerant to morethan 1% NaCl, was treated with buthiobate. The cells accumulated14a-methylsterols such as obtusifoliol, instead of campesteroland sitosterol. The buthiobate-treated cells lost their salttolerance. These results suggest that the buthiobate-inducedsalt sensitivity is closely associated with changes in the molecularspecies of sterols in the cell membranes. (Received October 16, 1986; Accepted April 13, 1987) 相似文献
2.
H. Akita Taeko Miyagi Keiko Hata Manabu Kagayama 《Histochemistry and cell biology》1997,107(6):495-503
Histochemical evidence is required to demonstrate the presence of biochemically defined cytosolic sialidase. To meet this
requirement, we examined the immunohistochemical localization of the enzyme in rat skeletal muscles. Sections of chemically
fixed tissues were incubated with a polyclonal antibody raised against a synthetic peptide which corresponded to a part of
the enzyme protein. After incubation with the primary antibody, cryosections for fluorescence microscopy and resin sections
for electron microscopy were incubated with a fluorochrome- and colloidal gold-labeled secondary antibody, respectively. Immunofluorescence
was diffusely distributed in the muscle fibers and was also found in the perimysium and blood vessels. Many immunogold particles
were scattered over the sarcoplasm, myofibrils, nucleoplasm, and matrix of mitochondria. The immunogold particles were also
found in the equivalent compartments of axons, Schwann cells, and cells of endomysium and blood vessels. The specificity of
the primary antibody was elucidated by immunoblotting and an immunoprecipitation test. These findings clearly indicate that
this type of sialidase is essentially located in the cytosolic compartment. Consequently, the name, cytosolic sialidase, will
be appropriate for this enzyme. Additionally it is indicated that this enzyme is also present in cells other than skeletal
muscle fibers.
Accepted: 29 January 1997 相似文献
3.
4.
Akitoshi Nakashima Mikiko Yamanaka-Tatematsu Naonobu Fujita Keiichi Koizumi Tomoko Shima Toshiko Yoshida Toshio Nikaido Aikou Okamoto Tamotsu Yoshimori Shigeru Saito 《Autophagy》2013,9(3):303-316
In early pregnancy, trophoblasts and the fetus experience hypoxic and low-nutrient conditions; nevertheless, trophoblasts invade the uterine myometrium up to one third of its depth and migrate along the lumina of spiral arterioles, replacing the maternal endothelial lining. Here, we showed that autophagy, an intracellular bulk degradation system, occurred in extravillous trophoblast (EVT) cells under hypoxia in vitro and in vivo. An enhancement of autophagy was observed in EVTs in early placental tissues, which suffer from physiological hypoxia. The invasion and vascular remodeling under hypoxia were significantly reduced in autophagy-deficient EVT cells compared with wild-type EVT cells. Interestingly, soluble endoglin (sENG), which increased in sera in preeclamptic cases, suppressed EVT invasion by inhibiting autophagy. The sENG-inhibited EVT invasion was recovered by TGFB1 treatment in a dose-dependent manner. A high dose of sENG inhibited the vascular construction by EVT cells and human umbilical vein endothelial cells (HUVECs), meanwhile a low dose of sENG inhibited the replacement of HUVECs by EVT cells. A protein selectively degraded by autophagy, SQSTM1, accumulated in EVT cells in preeclamptic placental biopsy samples showing impaired autophagy. This is the first report showing that impaired autophagy in EVT contributes to the pathophysiology of preeclampsia. 相似文献
5.
Tadashi Ogawa Takahiko Hlgasa Tadao Hata 《Bioscience, biotechnology, and biochemistry》2013,77(5):712-723
The proteinase inhibitors I (R-I) and III (R-III) isolated from Japanese radish seed were characterized in terms of their N-terminal amino acids, amino acid composition and reacting groups. The amino acid composition of two proteins differed from each other, while histidine, methionine and tryptophan contents were all low. N-Terminal amino acids of these inhibitors determined by Edman degradation were the same; valine.By modifying free amino groups in the inhibitors with trinitrobenzenesulfonic acid, R-III was greatly inactivated in proportion to the modification of amino groups, but the activity of R-I was not affected.However, modification of arginyl residues of R-I by cyclohexanedione reduced its activity. These results indicate that R-I is an arginine-type and R-III is a lysine-type inhibitor. 相似文献
6.
The polymeric cobalt(II) porphyrin complexes were prepared from cobalt(II) protoporphyrin IX dimethyl ester(Co(II)P) and copolymers of 4-vinylpyridine and styrene(PSP), and their binding ability of molecular oxygen was studied in toluene solution. The five- and six-coordinate structure of CoP-PSP complexes were confirmed by esr spectra. The esr parameters for the CoP-PSP complexes were not affected by the molecular weight and the vinylpyridine-unit content of PSP-ligand. The 1:1 dioxygen-Co complex was reversibly formed when the solution of CoP-PSP was exposed to oxygen atmosphere at low temperature. While the visible spectra and esr parameters for the dioxygen complexes of CoP-PSP were the same as those of the CoP-pyridine complex, the equilibrium constant for the oxygen binding increased with the vinylpyridine-unit content of the PSP-ligand. The larger entropy change was observed for the oxygenation in the CoP-PSP system especially, of which the vinylpyridine-unit content was large. 相似文献
7.
The d(G4) and d(C4) molecules in the single stranded state were synthesized by the phosphotriester method and purified. The full duplex of tetramer d(G4).d(C4) was prepared by expending about a month. The duplex-to-single strand transition was observed by UV-spectroscopy. A standard hypochromic effect was observed, which is different from some experimental results reported previously. 相似文献
8.
Li Wan Markus Koeck Simon J. Williams Anthony R. Ashton Gregory J. Lawrence Hitoshi Sakakibara Mikiko Kojima Christine Böttcher Daniel J. Ericsson Adrienne R. Hardham David A. Jones Jeffrey G. Ellis Bostjan Kobe Peter N. Dodds 《Molecular Plant Pathology》2019,20(2):211-222
During infection, plant pathogens secrete effector proteins to facilitate colonization. In comparison with our knowledge of bacterial effectors, the current understanding of how fungal effectors function is limited. In this study, we show that the effector AvrL567-A from the flax rust fungus Melampsora lini interacts with a flax cytosolic cytokinin oxidase, LuCKX1.1, using both yeast two-hybrid and in planta bimolecular fluorescence assays. Purified LuCKX1.1 protein shows catalytic activity against both N6-(Δ2-isopentenyl)-adenine (2iP) and trans-zeatin (tZ) substrates. Incubation of LuCKX1.1 with AvrL567-A results in increased catalytic activity against both substrates. The crystal structure of LuCKX1.1 and docking studies with AvrL567-A indicate that the AvrL567 binding site involves a flexible surface-exposed region that surrounds the cytokinin substrate access site, which may explain its effect in modulating LuCKX1.1 activity. Expression of AvrL567-A in transgenic flax plants gave rise to an epinastic leaf phenotype consistent with hormonal effects, although no difference in overall cytokinin levels was observed. We propose that, during infection, plant pathogens may differentially modify the levels of extracellular and intracellular cytokinins. 相似文献
9.
10.
Yosuke?Shida Kaori?Yamaguchi Mikiko?Nitta Ayana?Nakamura Machiko?Takahashi Shun-ichi?Kidokoro Kazuki?Mori Kosuke?Tashiro Satoru?Kuhara Tomohiko?Matsuzawa Katsuro?Yaoi Yasumitsu?Sakamoto Nobutada?Tanaka Yasushi?Morikawa Wataru?OgasawaraEmail author 《Biotechnology for biofuels》2015,8(1):230