全文获取类型
收费全文 | 15285篇 |
免费 | 791篇 |
国内免费 | 8篇 |
出版年
2022年 | 36篇 |
2021年 | 119篇 |
2020年 | 67篇 |
2019年 | 94篇 |
2018年 | 153篇 |
2017年 | 155篇 |
2016年 | 266篇 |
2015年 | 410篇 |
2014年 | 467篇 |
2013年 | 1217篇 |
2012年 | 842篇 |
2011年 | 911篇 |
2010年 | 528篇 |
2009年 | 514篇 |
2008年 | 844篇 |
2007年 | 948篇 |
2006年 | 928篇 |
2005年 | 965篇 |
2004年 | 1053篇 |
2003年 | 970篇 |
2002年 | 913篇 |
2001年 | 202篇 |
2000年 | 163篇 |
1999年 | 198篇 |
1998年 | 243篇 |
1997年 | 231篇 |
1996年 | 189篇 |
1995年 | 172篇 |
1994年 | 136篇 |
1993年 | 170篇 |
1992年 | 162篇 |
1991年 | 135篇 |
1990年 | 121篇 |
1989年 | 121篇 |
1988年 | 109篇 |
1987年 | 91篇 |
1986年 | 96篇 |
1985年 | 108篇 |
1984年 | 124篇 |
1983年 | 103篇 |
1982年 | 117篇 |
1981年 | 106篇 |
1980年 | 91篇 |
1979年 | 52篇 |
1978年 | 56篇 |
1977年 | 50篇 |
1976年 | 54篇 |
1975年 | 37篇 |
1974年 | 40篇 |
1973年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Taiichiro Okajima Toshiharu Motomatsu Ken-ichi Kato Hiroshi Ibayashi 《Life sciences》1980,26(9):699-705
Intraventicular injection of beta-endorphin (beta LPH61?91) in urethane anesthetized male rats led to a dose dependent increase of plasma prolactin levels. Intravenous injection of apomorphine completely abolished the stimulatory effect of beta-endorphin. Animals treated with 6-hydroxydopamine (6-OHDA) and 6-OHDA plus desmethylimipramine showed inhibition of beta-endorphin induced prolactin release. These results suggest that beta-endorphin presynaptically inhibits the activity of dopaminergic neurones, leading to the stimulation of plasma prolactin levels. 相似文献
2.
A low-pressure microwave-induced helium plasma serves as an excitation source for metal chlorides, nitrates, and sulfates vaporized from a filament, resulting in fractional vaporization and differential sensitivities of detection of the elements depending on the vapor pressures of their salts. The shapes of the single emission peaks, which are simple in the presence of potassium chloride, become complex and may double in number. 相似文献
3.
(1) The antagonistic effect of atropine methyl bromide entrapped in liposomes on contraction of Xenopus intestine in vitro induced by acetylcholine was studied. The results provided some insight into cell-liposome interaction. (2) Acetylcholine (0.1 mM) was added to the medium in the bath (serosal solution), while liposomes containing atropine methyl bromide in their internal and external phases were added on the mucosal side of the intestine. Large multilamellar liposomes were prepared from egg lecithin (phosphatidylcholine, PC) and cholesterol in various molar ratios. Atropine methyl bromide had most effect in liposomes composed of PC and cholesterol in a ratio of 7:3, less in those with a ratio of 4:5, and none in those with a ratio of 9:1. These effects were parallel with the sizes of these liposomes, determined by quasi-elastic light-scattering; that is, the larger the liposomes, the greater was their effect. Addition (to the liposomes) of phosphatidic acid, the negative charge of which increases the distance between the lamellar layers, increased the effect, indicating that atropine methyl bromide in the space between lamellar layers was effective. Another type of liposomes in which atropine methyl bromide was present only in the external phase of liposomes was as effective as liposomes in which atropine methyl bromide was present in both the internal and external phases. (3) From these results the following new model for liposome-mediated stimulation of transport of atropine methyl bromide is proposed. Large multilamellar liposomes have structural defects in their external lamellae through which atropine methyl bromide in the mucosal solution can penetrate into the space between the external lamellar layers and move into intestinal cells through regions of fusion between the outermost layers of the liposomes and the cell membrane. 相似文献
4.
5.
Mohammad Rashel Jumpei Uchiyama Iyo Takemura Hiroshi Hoshiba Takako Ujihara Hiroyoshi Takatsuji Koichi Honke & Shigenobu Matsuzaki 《FEMS microbiology letters》2008,284(1):9-16
A tailed bacteriophage, φMR11 (siphovirus), was selected as a candidate therapeutic phage against Staphylococcus aureus infections. Gene 61, one of the 67 ORFs identified, is located in the morphogenic module. The gene product (gp61) has lytic domains homologous to CHAP (corresponding to an amidase function) at its N-terminus and lysozyme subfamily 2 (LYZ2) at its C-terminus. Each domain of gp61 was purified as a recombinant protein. Both the amidase [amino acids (aa) 1–150] and the lysozyme (aa 401–624) domains but not the linker domain (aa 151–400) caused efficient lysis of S . aureus . Immunoelectron microscopy localized gp61 to the tail tip of the φMR11 phage. These data strongly suggest that gp61 is a tail-associated lytic factor involved in local cell-wall degradation, allowing the subsequent injection of φMR11 DNA into the host cytoplasm. Staphylococcus aureus lysogenized with φMR11 was also lysed by both proteins. Staphylococcus aureus strains on which φMR11 phage can only produce spots but not plaques were also lysed by each protein, indicating that gp61 may be involved in 'lysis from without'. This is the first report of the presence of a tail-associated virion protein that acts as a lysin, in an S. aureus phage. 相似文献
6.
Xiao-Xiao Li Bun Tsoi Yi-Fang Li Hiroshi Kurihara Rong-Rong He 《The journal of histochemistry and cytochemistry》2015,63(5):301-311
Cardiolipin (CL) is a unique dimeric phospholipid that exists almost exclusively in the inner mitochondrial membrane (IMM) in eukaryotic cells. Two chiral carbons and four fatty acyl chains in CL result in a flexible body allowing interactions with respiratory chain complexes and mitochondrial substrate carriers. Due to its high content of unsaturated fatty acids, CL is particularly prone to reactive oxygen species (ROS)-induced oxidative attacks. Under mild mitochondrial damage, CL is redistributed to the outer mitochondrial membrane (OMM) and serves as a recognition signal for dysfunctional mitochondria, which are rapidly sequestered by autophagosomes. However, peroxidation of CL is far greater in response to severe stress than under normal or mild-damage conditions. The accumulation of oxidized CL on the OMM results in recruitment of Bax and formation of the mitochondrial permeability transition pore (MPTP), which releases Cytochrome c (Cyt c) from mitochondria. Over the past decade, the significance of CL in the function of mitochondrial bioenergy has been explored. Moreover, approaches to analyzing CL have become more effective and accurate. In this review, we discuss the unique structural features of CL as well as the current understanding of CL-based molecular mechanisms of mitophagy and apoptosis. 相似文献
7.
8.
Guanethidine treatment or adrenal medullectomy significantly inhibited the elevation in blood pressure induced by Clostridium perfringens beta toxin, and the combination of the two drastically reduced the pressure rise, to less than 19% of that in control rats. When rats were pretreated with tetrodotoxin or hexamethonium, the toxin-evoked rise was significantly inhibited. Elevation in blood pressure induced by the toxin in spinal rats tended to be less than that in control rats. When investigated by a microscopical technique, arteriolar constriction in the mesenteric vasculature was observed after the blood pressure elevation induced by the toxin reached a maximum. Blood flow in the skin decreased with an increase in blood pressure following intravenous injection of the toxin. It is concluded that beta toxin acts on the autonomic nervous system and produces arterial constriction. 相似文献
9.
Junko Maeda Charles R. Yurkon Yoshihiro Fujii Hiroshi Fujisawa Sayaka Kato Colleen A. Brents Mitsuru Uesaka Akira Fujimori Hisashi Kitamura Takamitsu A. Kato 《PloS one》2015,10(12)
When energetic particles irradiate matter, it becomes activated by nuclear reactions. Radioactivation induced cellular effects are not clearly understood, but it could be a part of bystander effects. This investigation is aimed at understanding the biological effects from radioactivation in solution induced by hadron radiation. Water or phosphate buffered saline was activated by being exposed to hadron radiation including protons, carbon- and iron-ions. 1 mL of radioactivated solution was transferred to flasks with Chinese hamster ovary (CHO) cells cultured in 5 mL of complete media. The induction of sister chromatid exchanges (SCE) was used to observe any increase in DNA damage responses. The energy spectrum and the half-lives of the radioactivation were analyzed by NaI scintillation detector in order to identify generated radionuclides. In the radioactivated solution, 511 keV gamma-rays were observed, and their half-lives were approximately 2 min, 10 min, and 20 min. They respectively correspond to the beta+ decay of 15O, 13N, and 11C. The SCE frequencies in CHO cells increased depending on the amount of radioactivation in the solution. These were suppressed with a 2-hour delayed solution transfer or pretreatment with dimethyl sulfoxide (DMSO). Our results suggest that the SCE induction by radioactivated solution was mediated by free radicals produced by the annihilated gamma-rays. Since the SCE induction and DMSO modulation are also reported in radiation-induced bystander effects, our results imply that radioactivation of the solution may have some contribution to the bystander effects from hadron radiation. Further investigations are required to assess if radioactivation effects would attribute an additional level of cancer risk of the hadron radiation therapy itself. 相似文献
10.